# The GrubDAC



## cobaltmute

I made an off-handed comment in another thread and since people are asking for functionality in a board the haven't seen yet, I might as well make this public.

 I decided to build my father one of joneeboi's USB headphone amp for his birthday. I ordered myself some of his prototype boards and then I went to order the BantamDAC to go along with it in the case.

 And then I realized that I had a problem - the Bantam only has a full size USB jack. My father only ever carries a mini-USB cable with him, and I'm not about to make him carry another cable just for his birthday present.

 So I decided to come up with this:
 Full View




 Top View:




 Bottom View:




 What it is a PCM2707/WM8524 USB DAC that is designed to be a functional equivalent of the BantamDAC. It is the same size as the Bantam, just using a mini-USB instead of the full size USB. Hopefully anywhere you can use a Bantam you can use this.

 The PCM2707 takes the USB signal and converts it to I2S. This signal is fed to the Wolfson Micro WM8524. The unique feature of the WM8524 compared to other Wolfson DACS is that it uses a charge pump to create a ground referenced signal. This means that there are no output caps. It also runs off of 3.3V so both chips can run off of one voltage regulator, in this case a TPS79333, making for a relatively simple board.

 The schematic is attached. I know the PCM2707 section works as it is taken right from another working DAC I designed. The section around the WM8524 is pretty simple, so I don't think I mesed it up in anyway 
	

	
	
		
		

		
			





. 

 An example BOM for the board is here. The BOM does not include output jacks or a case. As for a case, it should fit in the same Box Enclosure that the Bantam fits in. The big thing right now is that PCM2707 seems to have gone into short supply.

 I've got PCBs on order right now that I should be getting in a week or so. Once I've built one for myself to prove I didn't screw up, I will have extras if people are interested.

 Any comments? I don't doubt that there will be something to be revised on this first version of the board.


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## cobaltmute

9/21/09 - Pictures of the board at Post#48
 9/21/09 - Excel BOM
 9/22/09 - Finished PICS
 9/22/09 - Boards available
 9/30/09 - Added a important note about integration with other devices when using USB power only for both.
 10/7/09 - Grub built as a CableDAC
 2/21/10 - Pictures and Notes of the production board


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## MisterX

You basically took the half schematic and description I posted in another thread and "designed" a DAC around it? 
 One of these days I will learn to keep my mouth shut. 
	

	
	
		
		

		
		
	


	




http://www.head-fi.org/forums/f6/lit...ma-1-a-438679/


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## cobaltmute

Hmm. While you may have a problem believing it, I did what I did based on the datasheet (pg21), so any resemblance there happens to be coincidental.

 It is not like it is a hard DAC to implement or anything.


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## nightanole

oooh oooh im in line for one. Then i can finish shoe horning everything into my esd wand case so work will wonder why it has a headphone jack.


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## blippster

I'll probably consider this to go with the Carries too, since it eliminates the DAC output caps. Here's to hoping pics will be up soon..


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## DKJones96

Nice job with the USB breakout. That's reason enough to want one of these to pair with a Carrie!


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## Billyk

Very nice. It is interesting that the reason you designed tthis was due to the USB in. My only complaint about the setup was exactly that, I wanted a mini-USB style input.
 If you need a prototyper, sign me up!


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## joneeboi

One of the limitations I had on my DAC attempt was to keep the giant USB connector in the same place as the Bantam supposedly for swappability, but I realize now that such a constraint is unnecessary. It's good to see another Bantam-sized DAC to go with the Carrie. I'll offer a few comments:

 - Why the pair of filter capacitors per channel on the output? Is that to allow the builder a choice between SMD and TH?

 - I fear some of those vias surrounding the PCM2707 are at risk of bridging, particularly on pins 2, 15 and 20. The ones on pins 2 and 15 sit close to ground pins, and if a bridge forms, it could be a headache undoing it. Pin 15 is carrying a high signal to boot. You have room, so moving them a bit further away could increase build success. Pin 2's via can be moved left a little bit so that bridging is erroneous, and the other two can be moved slightly farther from the pins.

 - I'm wondering about the LED placement. It will be hiding behind the rail caps on Carrie, so are you going to mount it on the panel?

 Other than that, I like it a lot. Just an excellent choice with the Wolfson, and I like the breakout holes near the USB. C9 is large enough for those low impedance, low voltage electrolytic capacitors to keep Carrie's DCP turned on, and the routing is intuitive and simple. This DAC will certainly go well with the Carrie. Got any extra boards? 
	

	
	
		
		

		
		
	


	




 edit: Also, I prefer the I2S signal going to the Wolfson over getting SPDIF out, but that's up to you to give us access to it.


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## cobaltmute

Quote:


  Originally Posted by *joneeboi* /img/forum/go_quote.gif 
_- Why the pair of filter capacitors per channel on the output? Is that to allow the builder a choice between SMD and TH?_

 

The output has a RC filter on it (per the datasheet). Through hole resistor and SMD capacitor. The resistors are through hole due to comments over at DiyHiFi about the nickel barrier on SMT resistors being "the worst sounding material known to man"

  Quote:


  Originally Posted by *joneeboi* /img/forum/go_quote.gif 
_- I fear some of those vias surrounding the PCM2707 are at risk of bridging, particularly on pins 2, 15 and 20. The ones on pins 2 and 15 sit close to ground pins, and if a bridge forms, it could be a headache undoing it. Pin 15 is carrying a high signal to boot. You have room, so moving them a bit further away could increase build success. Pin 2's via can be moved left a little bit so that bridging is erroneous, and the other two can be moved slightly farther from the pins.

 - I'm wondering about the LED placement. It will be hiding behind the rail caps on Carrie, so are you going to mount it on the panel?_

 

We'll have to see about the vias. I looked at the soldermask layer and there looks to be good mask around the vias. They are all in front of the pins as well so fixing any problems should not overly hard. You however have now got me a bit worried about pin 18 as it is underneath the chip. A possible correction for r2 of the board.

 As for the LED, I was never happy about the placement. In a standalone config, it is not an issue. In the Carrie, you can just remote it with wire to where ever you want. I may install it and just leave it on board for testing purposes as I don't think I need two indicator lights. I think I'll get it next to USB jack on the next revision

  Quote:


  Originally Posted by *joneeboi* /img/forum/go_quote.gif 
_ Got any extra boards? 
	

	
	
		
		

		
		
	


	


_

 

At this point, whenever they arrive, yes.


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## tomb

This looks very intriguing! Likewise, since we are working on the newest Millett MAX board to use an onboard Bantam - this would work, too.


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## ShinyFalcon

Do you think you can add some pads/holes that makes it easy to tap to the I2S lines? Actually maybe I can just solder wires on the unpopulated WM8524 DAC, seems like space is an issue.


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## Billyk

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_This looks very intriguing! Likewise, since we are working on the newest Millett MAX board to use an onboard Bantam - this would work, too._

 

That would be very nice!
 Have you thought about another rev of the Bantam using the USB-Mini style connector?


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## cobaltmute

Quote:


  Originally Posted by *ShinyFalcon* /img/forum/go_quote.gif 
_Do you think you can add some pads/holes that makes it easy to tap to the I2S lines? Actually maybe I can just solder wires on the unpopulated WM8524 DAC, seems like space is an issue._

 

I'm already playing with some possible layouts for r2 (gotta do something while waiting for the boards to arrive). I think it may be possible.


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## tomb

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_That would be very nice!
 Have you thought about another rev of the Bantam using the USB-Mini style connector?_

 

I'll see if cetoole will add it.


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## DKJones96

I don't know that I'd worry too much about those vias. The type of soldering job that an SMD chip like that takes shouldn't have enough solder on there to bridge with anyways.


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## mugdecoffee

What would be even better than a mini USB port is if these mini DACs had the option to use a male USB plug so you could plug the board straight into your laptop for extra portability. All the wires get messy when you connect the DAC to an amp, especially you're using them in a car or plane.

 Now that I think about it, the Carrie solves this problem well.


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## DKJones96

If you want the cleanest sound possible you want the digital signal to be carried and decoded as close to the amp as you can get it. Stay digital as far down the line as you can.


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## mugdecoffee

Quote:


  Originally Posted by *DKJones96* /img/forum/go_quote.gif 
_If you want the cleanest sound possible you want the digital signal to be carried and decoded as close to the amp as you can get it. Stay digital as far down the line as you can._

 

Maybe true but in this case we'd just be getting rid of the USB cable which could only help. My gripe is that if I'm using the bantam DAC in the car, there's a USB cable from my computer to the DAC, a cable from the DAC to my mini3, and then the headphone cable. It really becomes a mess quite easily.

 If you integrate the bantam or this new grub dac with the Carrie amp, its not a problem. But while the topic of usb connections is up, it'd be nice to have support for a male connector.


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## Juaquin

While more convenient, yes, the idea of the USB soundcard is to move the analogue circuitry as far away from the noise-inducing computer as possible. Otherwise there's not much point in using the DAC instead of the built-in soundcard, IMO. But yeah, if it can be worked in as an option without hindering anything else, why not?


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## mugdecoffee

The point of a USB sound card is to use a higher quality DAC with your computer. I don't think much electrical noise is caused by the DAC being physically close to the computer, especially not with laptops. Mostly the USB power rails have noisy power but the regulators on the bantam and grub DACs filter it out.


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## cobaltmute

Quote:


  Originally Posted by *mugdecoffee* /img/forum/go_quote.gif 
_Maybe true but in this case we'd just be getting rid of the USB cable which could only help. My gripe is that if I'm using the bantam DAC in the car, there's a USB cable from my computer to the DAC, a cable from the DAC to my mini3, and then the headphone cable. It really becomes a mess quite easily._

 

Not gaining anything as you'd still be a cable from the computer to the Mini^3 and from there the headphones.

 And you'd have this thing hanging off your computer that could get whacked and broken easily.

  Quote:


 If you integrate the bantam or this new grub dac with the Carrie amp, its not a problem. But while the topic of usb connections is up, it'd be nice to have support for a male connector. 
 

Isn't that the point of the Carrie - fitting the Bantam or this DAC and the Mini^3 into the same box as the Mini^3?


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## mugdecoffee

If you wanted to use the actual mini3 amp because you already have one or because you want to use the amp with other sources it'd be nice. You'd still have a cable to the mini3 but you could eliminate one more cable you'd have to carry and hook up. It may be a little fragile but not anymore so than a flash drive. Mostly it'd just be nice as an option especially it it would only take adding a few pads to the board. What I'm picturing is something like:
USB Sound Card with Virtual 7.1CH (C-Media Chipset) - China usb sound card, usb sound adpter, usb 7.1CH sound card in Sound Card

 It just seems silly to me to require two cables to connect such a small device.


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## tomb

Quote:


  Originally Posted by *mugdecoffee* /img/forum/go_quote.gif 
_If you wanted to use the actual mini3 amp because you already have one or because you want to use the amp with other sources it'd be nice. You'd still have a cable to the mini3 but you could eliminate one more cable you'd have to carry and hook up. It may be a little fragile but not anymore so than a flash drive. Mostly it'd just be nice as an option especially it it would only take adding a few pads to the board. What I'm picturing is something like:
USB Sound Card with Virtual 7.1CH (C-Media Chipset) - China usb sound card, usb sound adpter, usb 7.1CH sound card in Sound Card

 It just seems silly to me to require two cables to connect such a small device._

 

This is DIY. There's nothing that says you can't use a male USB plug instead of a female USB socket.

 Me? I'd rather have the cable anyday - I've snapped off enough flash drives to teach me the value of a cable. Once you start going that route, you have to consider the stresses of a mechanical connection with the cantilevered weight of the device hanging off the end, etc. It's not a pretty picture when the USB connector on the other end is directly connected to your laptop's motherboard. Ouch!


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## Billyk

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_This is DIY. There's nothing that says you can't use a male USB plug instead of a female USB socket.

 Me? I'd rather have the cable anyday - I've snapped off enough flash drives to teach me the value of a cable. Once you start going that route, you have to consider the stresses of a mechanical connection with the cantilevered weight of the device hanging off the end, etc. It's not a pretty picture when the USB connector on the other end is directly connected to your laptop's motherboard. Ouch! 
	

	
	
		
		

		
		
	


	


_

 

Working in an IT shop, this is a constant problem, I thank (insert deity of choice here) at least once a month that I spend the extra $$ for the complete type of coverage that includes accidents. I think that broken USB ports in laptops are the most common issue.
 I also prefer a cable although I do tend to get myself tangles up. My wife refuses to be seen with me when my portable rig gets out of control, says I look like a bomber or something...


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## tomb

Yep. There's also this adapter that will work with the Bantam -
USB Adaptor A M To B F USB Port Converter | Distributed By MCM | UA-002 (UA002)





 I haven't found one yet for a Mini-USB, but there's got be one out there.


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## cobaltmute

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yep. There's also this adapter that will work with the Bantam -
USB Adaptor A M To B F USB Port Converter | Distributed By MCM | UA-002 (UA002)





 I haven't found one yet for a Mini-USB, but there's got be one out there._

 

Isn't that the wrong one? Don't you need a USB A male to USB B male? You need to male B plug to go into the Bantam, I think.


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## Billyk

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yep. There's also this adapter that will work with the Bantam -
USB Adaptor A M To B F USB Port Converter | Distributed By MCM | UA-002 (UA002)





 I haven't found one yet for a Mini-USB, but there's got be one out there._

 

Yes, shouldn't that "innie" be an "outie"?


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## tomb

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Yes, shouldn't that "innie" be an "outie"?_

 

Nope -
Male B from Bantam plugs into Female B on adapter
Male A on adapter plugs into Female A on PC/laptop


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## Billyk

I may be confused....
 I am looking at the cable I use as my bantam is at home, but the cable I have looks like it would plug into that adapter just like it would plug into my bantam???


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## tomb

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_I may be confused....
 I am looking at the cable I use as my bantam is at home, but the cable I have looks like it would plug into that adapter just like it would plug into my bantam???_

 

Well, the discussion involved using a plug directly from a DAC - without a cable. That's why I posted that adapter pic. At least in the case of the BantamDAC, use of that adapter would allow one to plug the Bantam directly into a PCB USB slot, with no cable at all. Think about it - the adapter is the same as a cable with the intervening wiring.
	

	
	
		
		

		
			





 Frankly, I prefer to remove the cable from the other end (the RCA interconnect) and make a BantamCableDAC. I was just addressing the subject at hand in the thread, though. This all assumes one had a Bantam already built and the USB male connector was already soldered to the board. I hope that makes sense - didn't mean to be confusing.


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## cobaltmute

It's the Male B on the Bantam that tomb is talking about (which is different than stock). 

 Just thinking about how long that would stick out from a laptop would be a great way to get a new motherboard.


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## joneeboi

Quote:


  Originally Posted by *mugdecoffee* /img/forum/go_quote.gif 
_It just seems silly to me to require two cables to connect such a small device._

 

 Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Isn't that the point of the Carrie - fitting the Bantam or this DAC and the Mini^3 into the same box as the Mini^3?_

 

 Quote:


  Originally Posted by *mugdecoffee* /img/forum/go_quote.gif 
_Now that I think about it, the Carrie solves this problem well._

 

If you're intent on sticking with the Mini^3 for your amp, then you're going to have to live with that other cable, not to mention the one required for charging the battery. Carrie can be built for well under $100 if you play your shipping cards right. I think right now the best option is making orders at both Mouser and Digikey, and depending on shipping price, you can build a fairly low-cost, portable and high quality DAC/amp.


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## DKJones96

Case, panels and all, the Carrie and Bantam can be built together with around $100. It's about $60 in parts and $40 for the panels. I imagine this dac will be similar in price to build and pair.


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## Billyk

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_It's the Male B on the Bantam that tomb is talking about (which is different than stock). 

 Just thinking about how long that would stick out from a laptop would be a great way to get a new motherboard. 
	

	
	
		
		

		
		
	


	


_

 

Thanks! I was staring at that thing and at the cable on my desk.... Did not mean to be argumentative, and OT, I'm sorry about that; I just couldn't get it through my thick skull. Anyway I am a cable fan and if I didn't build my first Bantam for a Carrie, I would have been a cabledac type.


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## Juaquin

I was actually in the process of building a cable Bantam, but Carrie popped up before I finished so I switched to the USB socket. Great timing!


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## nullstring

cobaltmute: any word on the ability to add SPDIF out in r2?
 again, keep in mind that I am perfectly happy air wiring the forward voltage and the SPDIF as long as I have a place to do so.


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## cobaltmute

It is still a consideration. I actually want to build a first one before I get too far into the the second revision...


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## cobaltmute

Boards are now in the hands of FedEx and I should be getting them Tuesday.


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## cobaltmute

FedEx beat their own delivery standard and I ended up getting the boards today.

 Good news and some annoying news for those that are interested in the boards.

 The annoying news is that they were shipped as panels so I have snap them all apart. This means that edges of the boards are rough.

 The good news is that for some reason they shipped me two panels instead of one so I've got a lot more boards then expected, which means the price per board drops. A slight problem with this that I can already see is that the scoring on some of the boards sucks so some of the boards are right-offs.

 I'll post pictures later tonite when I'm not at work.


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## Billyk

Thats good news, I'd love a board (or two!), so please let me know.


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## pistolsnipe

did you find a source for the PCM2707?


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## cobaltmute

I don't have any miracle sources. I've got some on backorder from Digikey and one in my box. Mouser's ship date keeps sliding.


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## keyid

ill take a board or 2


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## mugdecoffee

I'd love to try a couple of boards out.


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## DKJones96

In for 2 as well when they are available


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## pistolsnipe

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_FedEx beat their own delivery standard and I ended up getting the boards today...I'll post pictures later tonite when I'm not at work._

 

The villagers demand pictures!!!


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## cobaltmute

Here is pictures:

 Top:




 Bottom:




 As I said in a PM to someone interested in the boards, I'm not going to consider selling any to anyone until I've at least built one. I need to know it works before I go down that route. I'm waiting on some SMD resistors (should get them tomorrow from Digikey).

 The only note on the boards is that due to the break-apart of boards, they are a fraction too large. A couple of quick passes on a file and they are perfect for sliding into the slot of a 1455C801 case as well as smooth for handling.


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## pistolsnipe

hey no problems, thanks for the pics, and the project effort. looks badass


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## DKJones96

We were talking about vias earlier and from the pics the only one I'd worry about is the one at C15.


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## cobaltmute

I've done the top soldering on the first board and the via under C15 came out clear.


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## cobaltmute

I figured I should attach this. It is a Excel spreadsheet of the BOM. It has all the parts (excluding output connectors and case). It also shows the footprint for those of you that want to look at alternative parts. 

 The BOM part numbers are all Mouser based as I tried to make shipping as simple as possible and Mouser carries the WM8524 while Digikey does not.

 EDIT: as a note as of 10/02/09, the Molex part on this spreadsheet is backordered at Mouser. This is a compatible part number: 56579-0519


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## Billyk

Looks very good. I am sure it will turn out great. Good luck with the build.


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## cobaltmute

It lives! 
	

	
	
		
		

		
		
	


	
















 Powered up and ran fine first try.

 My initial listening is through a Carrie (Mini^3) which is previously unknown to me but initial impression is a very lively sound that has been not been fatiguing at all in the first hour of listening. It has more than enough output to get me to drop my Carrie from gain 5 down to gain 2.

 I don't have anything to do a RMAA test as all my input sources suck so someone else is going to have to do the numbers. Doing a laymen's noise test (full volume with nothing playing), I can't hear anything. And anyways, I don't really care about the specs - for me the most important thing is that I like the sound.


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## cobaltmute

And now somebody is going to ask about boards.

 $2 CDN each (loving that overship from GoldPhoenix)
 $5 CDN for shipping by Canada Post.

 PM me your address and the number of boards you want. I'll get your package ready and PM you my paypal address and the boards will get in the mail the next day after you pay.


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## mugdecoffee

Do you have a Bantam that you could compare it too?


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## cobaltmute

Bantam no, Alien yes. But my Alien is at work and I wouldn't be able to compare until much later today.


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## cobaltmute

Someone PM'ed me that the TPS reg I listed on the BOM is on backorder.

 You can use either of these instead:
 595-TPS79333DBVREP
 595-LP2985A-33DBVR

 The first one is the enhanced reliability version of the one I originally listed. It is $0.14CDN more in cost.

 The Mouser online BOM has been updated to the in-stock TPS.


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## cobaltmute

For the record, I've added a mylar isolator for the crystal to the Online BOM. Optional but probably a good idea to isolate the metal case from the top groundplane.


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## nightanole

Looked over the spec on the wolfson. 2vrms out put, thats ubber high. I can see why you could drop the gain so much. the bantam is only 1vrms and the very loud gamma 1 is 1.6vrms. 2vrms is 5.66pp, thats enough to pop the 2gain carrie.


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## cobaltmute

I was just looking at R6 and R7, the through hole resistors that are part of the output filter.

 There is a couple of options that you can use here:
 - The spec'ed RN50.
 - You can use CMF50 in the same place which is the same resistor in non-Military grade.
 - CMF55 (and of course RN55) fit in the position. They are tight, but they do fit.
 - Xicon MF-RC 270 series
 - Panasonic EROS2

 and probably some others.

 I'd stick with a good quality option here. These are directly in the signal path and you want something decent here.


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## keyid

would a tombstoned 100ohm carbon film work well for r6/r7?


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## cobaltmute

I would think you can get away with it. R6/7 are a simple low pass filter so it shouldn't be too sensitive to orientation. 

 As for carbon versus metal film, that would seem to be personal preference. The only reason I didn't do SMD for these positions was some negative comments to the nickel barriers I've read and the not nickel ones were $17 a resistor.


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## stwspoon

I have a few observations based on my build and eval of the HPDAC last year. 
 Looking at your schematic, PSEL on the PCM270x is grounded, On the HPDAC it is pulled up to indicate 500 ma power to the host. Maybe have a few smt resistor pads or jumpers to select pull up or pull down based on how the user will power the grubdac.

 HOST is tied to Vdd on the GrubDac and is tied to VBus (through a ferrite) on the HPDac. This would be useful so that the PCM270x can properly detect when the usb is inserted when the grubdac is not USB powered.

 Also could the SSPND pin be brought out to a pad? It may be useful in reducing inrush currents by keeping the DC/DC converter on a Carrie disabled until a few milliseconds after the USB is inserted ( see page 26 of the PCM270x data sheet for the power up timing)

 Definitely add me to your list for your next round of boards.


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## cobaltmute

Quote:


  Originally Posted by *stwspoon* /img/forum/go_quote.gif 
_I have a few observations based on my build and eval of the HPDAC last year. 
 Looking at your schematic, PSEL on the PCM270x is grounded, On the HPDAC it is pulled up to indicate 500 ma power to the host. Maybe have a few smt resistor pads or jumpers to select pull up or pull down based on how the user will power the grubdac._

 

I suggest you re-read the meaning of PSEL. It does not indicate the power consumption of the device - it specifies how the PCM2707 is getting its power.

  Quote:


 HOST is tied to Vdd on the GrubDac and is tied to VBus (through a ferrite) on the HPDac. This would be useful so that the PCM270x can properly detect when the usb is inserted when the grubdac is not USB powered. 
 

Again check the datasheet for what HOST does. The options for what you want to do with PSEL/HOST don't work as a combination for Power/Bus Detection.

 I'll have to consider the not-powered by USB options. It was not something that was an initial design consideration. I have run these settings with external power on my other DAC design and it did work and function, but probably breaks a bunch of USB standards.

  Quote:


 Also could the SSPND pin be brought out to a pad? It may be useful in reducing inrush currents by keeping the DC/DC converter on a Carrie disabled until a few milliseconds after the USB is inserted ( see page 26 of the PCM270x data sheet for the power up timing) 
 

Again, something I'll consider but possible a good use for that pin. The only problem is to latch on the DC/DC once power is established as SSPND will go low again after power on.

  Quote:


 Definitely add me to your list for your next round of boards. 
 

There is still a lot of the first round boards available.


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## cobaltmute

I've added an alternate J1 USB connector to the online BOM as the original is out of stock.

 I have listed both, but you only need one. When the cheaper option is back in stock, I will remove the more expensive one.


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## stwspoon

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_I suggest you re-read the meaning of PSEL. It does not indicate the power consumption of the device - it specifies how the PCM2707 is getting its power._

 

That is right. PSEL specifies how the PCM2707 is getting power TO THE HOST via the configuration descriptor( p 16). What shuts down the onboard regulator is connecting Vbus to Vcc. In bus powered mode, HOST just toggles the 100ma /500 ma flag in the configuration descriptor.

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Again check the datasheet for what HOST does. The options for what you want to do with PSEL/HOST don't work as a combination for Power/Bus Detection. 

 I'll have to consider the not-powered by USB options. It was not something that was an initial design consideration. I have run these settings with external power on my other DAC design and it did work and function, but probably breaks a bunch of USB standards._

 

Yea, what meets USB spec and what mostly works is quite different. DAMHINT. I learned a lot wrestling with the TPS61170 boost regulator on the HPDAC. The DCP design in Carrie is much better. Most USB host devices will let you draw ~ 500 ma (900 ma for USB 3.0
	

	
	
		
		

		
			





) without looking at the config descriptor, but not all.

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Again, something I'll consider but possible a good use for that pin. The only problem is to latch on the DC/DC once power is established as SSPND will go low again after power on.



 There is still a lot of the first round boards available._

 

Great! I thought they were all gone. I must have gotten confused with the Carrie boards as that is what I want to pair it with.


----------



## cobaltmute

Quote:


  Originally Posted by *stwspoon* /img/forum/go_quote.gif 
_That is right. PSEL specifies how the PCM2707 is getting power TO THE HOST via the configuration descriptor( p 16). What shuts down the onboard regulator is connecting Vbus to Vcc. In bus powered mode, HOST just toggles the 100ma /500 ma flag in the configuration descriptor._

 

I'd really like something to backup the comment shutting down the regs. If that is true, I can see where you are going and it looks like it would be somewhat easy to implement. The only issue (compared to what is done now) is to separate out the power to the on-board regulator from Vbus.


----------



## nightanole

Its true that vcc to host and psel to ground shuts down the internal regs, its the way the gamma dac does it.


----------



## cobaltmute

I'm well aware of what the gamma1 does.

 But the concept is that Vbus or Vdd to Vcc alone shuts down regulators is a good idea. This allows us to put PSEL high, indicating to the PC that the DAC is bus-powered. This allows us to use the HOST pin to tell the PC that we are going to pull upto 500mA. In the case where the Carrie is attached, it helps us ensure the proper power is available

 The way I've done it, which is the same as the gamma1, tells the PC that the DAC is self powered, which by USB standards only allows 100mA draw. As amb says, a number of stupid devices always pull more so do we worry about it?


----------



## nightanole

Ya my light up snow men and fans use the 5v from usb and the pc could care less. I wonder if this whole 100ma-500ma key is for older usb 1.0 buses.


----------



## stwspoon

Here is where I got my info from:
ecp.cc

 Specifically the notes around VR3 near the bottom of the page.

 Also diyaudio has several long threads on getting the PCM270x to work
Another PCM2707 problem... - diyAudio
USB powered NOS USB DAC with built-in headphone amp - diyAudio

 On not backfeeding the USB bus in self powered mode 
USB interface NOS DAC?? - Page 2 - diyAudio


----------



## stwspoon

Desktop PCs usually don't care about USB power, but laptops and bus powered USB hubs can be more particular. They all current limit as part of the spec is a test where each USB pin is shorted to the others for 24 hrs to simulate a cable being smashed/shredded/cut/etc. The port doesn't have to work afterwards, but it can't catch fire 

 I have a docking station that I can't plug my USB fan into, but it works fine in the laptop.


----------



## cobaltmute

I've added a note to the Carrie thread about my issues with power and startup. This contains important information if you are going to integrate the GrubDAC with something else and draw all power from the USB bus.

 It appears the stwspoon is correct about the pin settings and power draw when having the DAC integrated with another device. If fact, I just Googled this tidbit:USB-IF Compliance Updates

 In r1b of the board, PSEL with be set high which tells the host it is bus-powered. HOST is already high (indicating 500mA) and since all power comes from the USB bus, I'm not worried about disconnect/reconnect issue.

 This issue will not affect stand-alone GrubDACs and may or may not affect GrubDAC + Carrie setups depending upon your PC hardware.

*EDIT: I've updated the Carrie thread  with an easier fix to this issue.*


----------



## amc

If you have boards left I would like 2. Sent PM


----------



## cobaltmute

There is still a bunch of boards available if some are interested.

 On a different note, PCM2706/7 seem to be in short supply. Digikey's shipping date has slipped to Oct 12 on the PCM2707. Mouser is slipping their dates as well.


----------



## joneeboi

If you're really desperate, you could probably grab some from amb. Think you'd need to stock up some PCMs to match the number of boards you ship? Same way amb does it.


----------



## cobaltmute

Quote:


  Originally Posted by *joneeboi* /img/forum/go_quote.gif 
_If you're really desperate, you could probably grab some from amb. Think you'd need to stock up some PCMs to match the number of boards you ship? Same way amb does it._

 

Personally, I'm not desperate, just letting people know.

 It is also a big jump from selling a few boards to having to ship static sensitive devices. And if I was to handle parts I'd go the whole way and deal with kits.


----------



## stwspoon

I ran across some more good USB design info at 
http://rfdesign.com/next_generation_...le_2_Final.pdf
 Check out the physical layout recommendations. Just something to think about if/when you do another set of boards. 

 Also when tying pins high or low, use a trace to a set of smt resistor pads with a trace between them, so you can cut the trace to disconnect the pin and later use a smt resistor to reconnect the pin again. Also bring all unused pins out to a pad or via.

 Pin >---[pad]--x--[pad]--gnd or Vcc (cut at x to disconnect pin)


----------



## Billyk

Wouldn't ya know! I went to order my Grubdac parts from Mouser and the mini-B is back ordered until December! Will the min-AB work, the pinouts look the same and everything I can find says that the AB will accept the B but I wanted to ask first. Thanks


----------



## stwspoon

I was going over the BOM for GrubDAC and I noticed that C9 is 1000 uf!! The USB spec for the TOTAL capacitance on Vbus for an upstream port ( on the device, not the host) is between 1 and 10 uf. You might want to try a smaller cap 
	

	
	
		
		

		
			





 This might be your surge problem.


----------



## cobaltmute

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Wouldn't ya know! I went to order my Grubdac parts from Mouser and the mini-B is back ordered until December! Will the min-AB work, the pinouts look the same and everything I can find says that the AB will accept the B but I wanted to ask first. Thanks_

 

Molex part is 56579-0519 compatible. You can see here as reference. I used the same part as the gamma1.

 And if you see here, it should be on the Mouser online bom link (both are on the BOM so you need to remove the backordered one).


----------



## cobaltmute

Quote:


  Originally Posted by *stwspoon* /img/forum/go_quote.gif 
_I was going over the BOM for GrubDAC and I noticed that C9 is 1000 uf!! The USB spec for the TOTAL capacitance on Vbus for an upstream port ( on the device, not the host) is between 1 and 10 uf. You might want to try a smaller cap 
	

	
	
		
		

		
		
	


	




 This might be your surge problem._

 

The is the same size part as the BantamDAC C7 which has been around for quite a while. The Grub has powered up on my laptop with no issues.


----------



## Billyk

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Molex part is 56579-0519 compatible. You can see here as reference. I used the same part as the gamma1.

 And if you see here, it should be on the Mouser online bom link (both are on the BOM so you need to remove the backordered one)._

 

Thanks, that'a the one I used. I did not use the online BOM I did use the excel sheet though, thanks for that.


----------



## cobaltmute

I've added a note to the Excel post about the part so people see it.


----------



## keyid

oh yea got it up and running with the carrie! sounds really great! Coming from the bantam its got a more expansive sound and much more lively.


----------



## cobaltmute

Glad to hear that you got it running.

 Any notes from the build?


----------



## keyid

The build went pretty smooth. I tried kwame 100ohm resistors for R7/6, after listening to the default and couldn't hear much of a difference. Led should be placed near the usb, also it would be nice to have the G,OR,OL in a line sequence instead of 2x2 block. I connect 5v on the carrie to the V+ and 0v on the carrie to GND, which I think is correct. 

 Overall, im impressed with the dac. I have two mini3 amps with alien dac (blackgates bypass with vitaminq) and bantam dac (visnay/cerafines) and imo the grub sounds much better with the mini3/carrie.


----------



## joneeboi

I got my boards the other day, and now I'm not sure what to do in regards to ordering parts. I'll have to wait on it a while. Good to hear it's getting a good reception. I can't wait to build mine.


----------



## keyid

try getting 2707 on ebay, I got two for $7.


----------



## cobaltmute

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_The build went pretty smooth. I tried kwame 100ohm resistors for R7/6, after listening to the default and couldn't hear much of a difference. Led should be placed near the usb, also it would be nice to have the G,OR,OL in a line sequence instead of 2x2 block._

 

For the next revision of the board, I've moved everything about. One of the key things was to get the LED next to the jack.

 I'll look into the output block. It was easier to go 2x2 rather that 1x4. I did two OGs as I saw a comment in the BantamDAC info that people had asked for that and I was trying to be as compatible as possible.

  Quote:


 I connect 5v on the carrie to the V+ and 0v on the carrie to GND, which I think is correct. 
 

That would be correct.


----------



## cobaltmute

Quote:


  Originally Posted by *joneeboi* /img/forum/go_quote.gif 
_I got my boards the other day, and now I'm not sure what to do in regards to ordering parts. I'll have to wait on it a while. Good to hear it's getting a good reception. I can't wait to build mine._

 

Farnell in Singapore has 48 PCM2707 in stock. ~$25 shipping to Canada though.
 Almost worth it to get a couple...


----------



## keyid

having two OG behind each other is fine. Having OG, OR, OL in a line would be great and match the carries sequence so there are no wires looping each other.


----------



## stwspoon

Just a suggestion, If the SSPND output drove the LED (through a transistor - only 2 ma output ) then you could see when the pc has disabled the output for some reason.


----------



## cobaltmute

Quote:


  Originally Posted by *stwspoon* /img/forum/go_quote.gif 
_Just a suggestion, If the SSPND output drove the LED (through a transistor - only 2 ma output ) then you could see when the pc has disabled the output for some reason._

 

I like the idea, but it is not foolproof. The PCM goes into suspend after 5ms of no music as well (datasheet, pg 27), so as an "active" indicator it is not useful.

 Now using a bi-color LED with red as power and green as music might be cool. I'd have to kill something (likely C9) to get the parts I needed in the right spot and it still would be a pain to route the SSPND to that spot.


----------



## KT88

Just wanted to let you guys know, seems the PCM2707 is back in stock a mouser.

 BTW, did someone try mouser 546-1551JTBU as a case? It looks quite nice (available in other colors as well), and looking at the PDF, it seems the screw holes are the exact right size for the PCB. Only question is, is there enough space between the two plastic parts for the PCB to fit in while allowing the case to be closed.


----------



## cobaltmute

Quote:


  Originally Posted by *KT88* /img/forum/go_quote.gif 
_Just wanted to let you guys know, seems the PCM2707 is back in stock a mouser._

 

Good to know.
  Quote:


 BTW, did someone try mouser 546-1551JTBU as a case? It looks quite nice (available in other colors as well), and looking at the PDF, it seems the screw holes are the exact right size for the PCB. Only question is, is there enough space between the two plastic parts for the PCB to fit in while allowing the case to be closed. 
 

There is only 15mm total height for that case so it may be a bit small.

 Now, once I get some PCM2707s, I have the parts to build it in a 1551HTBU. I think the extra 5mm in height should make it workable. I did order lower height caps for C9/C10 so we will have to see. The board does have to be modified with a Dremel to fit into the case and I may have to modify the case as well.


----------



## cobaltmute

Quote:


  Originally Posted by *KT88* /img/forum/go_quote.gif 
_BTW, did someone try mouser 546-1551JTBU as a case? It looks quite nice (available in other colors as well), and looking at the PDF, it seems the screw holes are the exact right size for the PCB. Only question is, is there enough space between the two plastic parts for the PCB to fit in while allowing the case to be closed._

 

Thought about this some more on the way to work.

 C9/C10 are the caps that are the big height offenders. You could use SMT ceramics across the pads, but you get to $$$ for the quality chips in high capacitance.


----------



## KT88

I think I'm gonna put one of them in the plastic box, and the other inside an aluminum box with a pimeta (v1) amplifier (and the third in the usual hammond case like the one for the mini^3/Carrie/y1 
	

	
	
		
		

		
			





).

 I want to be able to switch between RCA input and the DAC, but there's just too many options at mouser. Can someone please help me find a nice switch/toggle for this?


----------



## cobaltmute

Quote:


  Originally Posted by *KT88* /img/forum/go_quote.gif 
_I think I'm gonna put one of them in the plastic box, and the other inside an aluminum box with a pimeta (v1) amplifier (and the third in the usual hammond case like the one for the mini^3/Carrie/y1 
	

	
	
		
		

		
		
	


	




).

 I want to be able to switch between RCA input and the DAC, but there's just too many options at mouser. Can someone please help me find a nice switch/toggle for this?_

 

http://www.head-fi.org/forums/f6/sim...8/#post6016813

 I've been thinking about the same thing, switch RCA and DAC in an amp, only for me I think it is going to be a CTH or CK2III.


----------



## KT88

Hi Erik,

 Do you happen to know the mouser PN for a suitable item? I got lost in the tens of thousands of item's they have in that category


----------



## cobaltmute

Honestly, I haven't gotten that far in my planning yet. You may want to make a thread of it and someone else may see it and be able to help.


----------



## cobaltmute

GrubDAC as a cable dac in the aforementioned 1551HTBU.


 General Pic:




 Detail:




 Stupidly Bright White LED shining through the case:




 To do this you need to:
Cut two corners off the board.
Choose short caps for C9 and C10
Depending upon how short of caps you chose for C9 and C10, you may need to remove the 2 circuit board "bosses" in the case to get the board closer to the bottom. In my case I actually used a drill to remove them
If you had to remove the bosses, there is some "supports" for the board on the two pillers that the lid screws into that need to be removed. An Xacto worked well on these.
Drill holes for the two screws (1/8)" and the end grommets (1/4")
Use 4/40 nylon screws to avoid scratching anything the DAC sits on and use washers on the inside to ensure the DAC doesn't sit on the bottom of the case.
The other item of note is the USB drain wire. It will not fit in the Ground Holes. What I did was take the drain and the ground from the USB cable and put them in one of the holes of the USB connecter and then jumpered that to the GND positions (as the USB mounting holes are not connected to anything)

 For this one, I used United Chemi-con polymer caps (PS-A and PS-E). They have quite large capacitance for the size 
	

	
	
		
		

		
		
	


	




 The big pain about this is trying to get the DAC into the case after you've soldered the wires on. It is a PITA, but it can happen. I like have the translucent case with the LED shining through as an effect.

 I suspect that you should be able to do fit a Bantam in this same Hammond case. I did a search, but didn't find anybody doing it (but I might have searched wrong
	

	
	
		
		

		
		
	


	




).


----------



## dg3f

i am strongly recommending you to add a headphone amp ic part using max9722,it's also powered by a charge-pump ,it has powerful output and low thd+n.comparing with any other charge pump based headphone amp ic ,its price is reasonable while its proformance is not bad(only not as good as Ti's tpa6130,but note that tda6130 is QFN package and not easy to purchase),max9722 must be a good addtion to this project


----------



## cobaltmute

If I do anything for headphones it will be optional.

 And when choosing a white LED be wary of its Luminous Intensity. The one I chose lights up a dark room on 3mA. Must have chosen a flashlight LED.


----------



## mugdecoffee

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_I suspect that you should be able to do fit a Bantam in this same Hammond case. I did a search, but didn't find anybody doing it (but I might have searched wrong
	

	
	
		
		

		
			





)._

 

I used that case for my bantam (and it may soon be replaced by a grub dac after my next mouser order). The case is the perfect size really. I just took an exacto knife to some of the plastic and trimmed the corners a bit with a dremel though you might be able to get away with just breaking them off with a pair of pliers.


----------



## JamesL

^
 I used it for my bantam dac too last year
http://www.head-fi.org/forums/5060945-post302.html

 Instead of cutting off the corners, I filed it down a little so it still grabbed onto the sides of the case firmly.


----------



## Billyk

Looks great. It is a nice solution for use as a "cable" DAC.


----------



## cobaltmute

Quote:


  Originally Posted by *JamesL* /img/forum/go_quote.gif 
_^
 I used it for my bantam dac too last year
http://www.head-fi.org/forums/5060945-post302.html

 Instead of cutting off the corners, I filed it down a little so it still grabbed onto the sides of the case firmly._

 

Your post says 1551h as the case - I try the Google search for Head-FI and it doesn't come up with your post.

 Knew I couldn't have been the first. This case was just a little too obvious of a choice.

 EDIT: forum search found it, but Google couldn't


----------



## cobaltmute

Quote:


  Originally Posted by *dg3f* /img/forum/go_quote.gif 
_i am strongly recommending you to add a headphone amp ic part using max9722,it's also powered by a charge-pump ,it has powerful output and low thd+n.comparing with any other charge pump based headphone amp ic ,its price is reasonable while its proformance is not bad(only not as good as Ti's tpa6130,but note that tda6130 is QFN package and not easy to purchase),max9722 must be a good addtion to this project_

 

I was just listening to my 60Ω Senns directly off the Grub. It will drive them, but you can tell the output stage of the WM8524 is not happy driving that low of a load. You get some noticeable harshness in the high end.


----------



## cobaltmute

Just curious if anyone else has managed to build one yet?


----------



## Billyk

Mine's on the bench. I am waiting for a few bits from Mouser, short on time and funds lately. Hope to finish soon. The mouser order has parts for another Carrie to mate with it.


----------



## keyid

I have two grubs built in two carrie amps. Anyone need two bantams, mini3, alien dac? pm me


----------



## cobaltmute

Take it you like? 
	

	
	
		
		

		
		
	


	




 It does seem to be very nice with the Carrie.


----------



## blippster

I've completed one, with another that has a problem somewhere - I suspect it has to do with the PCM2707 soldering as there's no USB detection.

 The working one is mated with a Carrie, and sounds pretty good except a slightly harsh top-end with the Shure 840s.

 Design-wise, not much to add that hasn't already been said - having an LED next to the USB and SPDIF output would be nice.


----------



## cobaltmute

Quote:


  Originally Posted by *blippster* /img/forum/go_quote.gif 
_The working one is mated with a Carrie, and sounds pretty good except a slightly harsh top-end with the Shure 840s._

 

Interesting. The 840s are 44Ω. I've got a set of SE210 (26Ω) and a couple generic earbuds (32Ω). I found for these phones that the Carrie+Grub was a little bright and harsh with these, but with my 60Ω Sennheiser HD 440 II, the high end edge disappears and smooths out (or maybe it is the phones).

 My standalone Grub is at work so I've got to build another one to do further testing.


----------



## cobaltmute

Quote:


  Originally Posted by *blippster* /img/forum/go_quote.gif 
_I've completed one, with another that has a problem somewhere - I suspect it has to do with the PCM2707 soldering as there's no USB detection._

 

Is there no detection or does it have an error? 

 I'd ohm out
the D+ line
the D- line
through R1 to D+
and crossing the D+ and D- to see for bridges.

 The way I check for bridges on the PCM2707 (and any SMD chip), is to look through my ring magnifier light. I line the pins up I want to check perpendicular to my body and then tilt the board down to see between the pins. I find doing this I can really see what is happening between the pins compared to looking straight down on them.

 EDIT:

 Do you have power on the board? Check for 3.3V post the regulator. Either end of L3.


----------



## blippster

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Interesting. The 840s are 44Ω. I've got a set of SE210 (26Ω) and a couple generic earbuds (32Ω). I found for these phones that the Carrie+Grub was a little bright and harsh with these, but with my 60Ω Sennheiser HD 440 II, the high end edge disappears and smooths out (or maybe it is the phones)._

 

Thanks cobalt. It might well be the phones, as it seemed okay during the short listen I had with the ER4S, but haven't really had time to do a comparison with other phones yet.


  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_EDIT:

 Do you have power on the board? Check for 3.3V post the regulator. Either end of L3._

 

No power post-reg, so that's something I'll check as well when I have some time. Now seems pretty likely I made some silly error somewhere.


----------



## cobaltmute

It is one thing about the board. The LED is driven right off the USB power, so it is an indication of bus power, not board power. I'm adding a 3.3V test point on the next version of the board.


----------



## mugdecoffee

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Just curious if anyone else has managed to build one yet?_

 

Finally got a pcm2707 chip so next mouser order I made, I'll get the rest of the parts. I'll make sure to post impressions once I get it up and running.


----------



## blippster

Just a short update - the second Grub is up and running. I still think the PCM chip was the main problem, but reflowing that, the regulator and a few other iffy joints seems to have cleared it up.

 Test points would be good, yes. Maybe 5V/GND pads on the side opposite the USB jack could be useful when mating with a Carrie, but I somehow doubt the board has space for that.

 Anyway, nice one cobalt


----------



## cobaltmute

Quote:


  Originally Posted by *blippster* /img/forum/go_quote.gif 
_Just a short update - the second Grub is up and running. I still think the PCM chip was the main problem, but reflowing that, the regulator and a few other iffy joints seems to have cleared it up.

 Test points would be good, yes. Maybe 5V/GND pads on the side opposite the USB jack could be useful when mating with a Carrie, but I somehow doubt the board has space for that.

 Anyway, nice one cobalt 
	

	
	
		
		

		
		
	


	


_

 

Great that it works.

 In the next revision, there will be the USB breakout right next to the USB jack as well as 5V/GND on the opposite side (next to the Carrie).


----------



## mugdecoffee

Got a box of parts today and got my grub dac up and working first try. The soldering was not to bad after doing a couple other surface mount projects but I still had a couple of resistors fly across the room. I haven't had a change to sit down and compare it yet to my bantam or opus dacs but I'll post impressions when I do. I did briefly run my k240 sextetts directly off of it. They have a 600ohm impedance but the max volume was about as loud as I'd ever listen.

 Thanks for this cool little project.


----------



## cobaltmute

I was just checking the online BOM and some capacitors are listed as backordered. All of these have easy replacements. 

 The PCM2707 is out of stock again. I do have a small quantity (5) that I will let go at my cost. PM me if you need one.

 I think I will order a bunch to have available with the next run of boards.


----------



## Toez

Hi cobalt. 

 i ahve a question about yout PCB layout, What program did you use, i use Diptrace and Eagle but i cant find any matching ic for the pcm2707, do i have to make it myself or is there any in the application.

 Great job, looks very nice


----------



## cobaltmute

Quote:


  Originally Posted by *Toez* /img/forum/go_quote.gif 
_Hi cobalt. 

 i ahve a question about yout PCB layout, What program did you use, i use Diptrace and Eagle but i cant find any matching ic for the pcm2707, do i have to make it myself or is there any in the application.

 Great job, looks very nice 
	

	
	
		
		

		
		
	


	


_

 

I use National Instruments Electronic Workbench (Multisim for schematic capture and Ultiboard for PCB layout). I had to setup the part myself which didn't work right the first time.

 As for Eagle, this might be useful. Google is your friend. 
	

	
	
		
		

		
		
	


	




 EDIT: I should note that I've only found that Eagle library (the URL was posted here on Head-Fi) - I've never used it.


----------



## nullstring

This thread hasn't moved in a while. I was just curious to know how development is going, and if there is any other news anyone would like to share.


----------



## tomb

Quote:


  Originally Posted by *nullstring* /img/forum/go_quote.gif 
_This thread hasn't moved in a while. I was just curious to know how development is going, and if there is any other news anyone would like to share._

 

Well, cobaltmute contacted me recently for hole dimensions on the BantamDAC so we'd have commonality between the two designs, so I know he's working on it.


----------



## cobaltmute

I've got the next revision of the board done. There is some changes in footprint on some of the parts (from 1206 to 0805) and a general re-layout of the board to do things like get the LED near the USB, output near the Bantam output and put a power header on the far side from the USB to make it easier to power a Carrie board.

 What I've been waiting on is feedback from the builders to see if there is anything else that needs to be done. So far the design must be pretty stable as the comments have been minimal and mostly focused on re-locating the the LED.

 I'm trying to decide when it will be worth doing the next run of boards. The other issue is who to have make the boards. I'd like to go with someone like Imagineering, but the number of boards I need to have produced to make it cost effective is high and I don't know how long I want to sit on a board inventory. Nevermind the fact that I still have half the boards from the first run still in my possession.

 As for the Grub2 (which would add some SPDIF and I2S headers and other tiems), that has been on hold until now as I wanted to finalize the revisions to the first board. I know what I'd like to do, now it is just executing that idea.


----------



## cobaltmute

I've done some maintenance on the Mouser online BOM to ensure that as much is in stock as possible.

 The stock part for J1 is on backorder again - J1 alt has been added to the online BOM at a small price increase. You need to remove J1 yourself (I list both in case one comes back into stock).

 I also had to change a few capacitors to in-stock versions.

 The WM8524 is out of stock now, but there is stock on the PCM2707, go figure.


----------



## nullstring

keep up the good work =)

 Do you plan on making the Grub2 the same size of the Grub?


----------



## cobaltmute

Losing my mind - I thought I responded to this this morning.

 If I get what is in my head on PCB the way that I want to, Grub2 will fit in the same volume as Grub1


----------



## mfaughn

Hi all,

 I "finished" my build the other night. It isn't working. When I plug it in the OS (XP) tells me something along the lines of...

USB device not recognized...malfunctioned...yada yada yada.

 I have 3.3V at L3. I have ohmed out all the pins on U1, U2 for solder bridges. Re-flowed them and ohmed them out again. I've also verified that pins that should be connected are connected (on U2, will check U3 again). I've started tracing through the rest of it but it is kinda hard on a two sided board.

 This is only the third or fourth time I've done any SMD work. It isn't pretty but I am reasonably sure that all of my connections are sound and that I don't have any bridges.

 Can anyone recommend any further course of action? How likely is it that I cooked a chip?

 Thanks,
 Michael


----------



## cobaltmute

Is this attached to something else (i.e like a Carrie)?

 I would re-check the resistors R1, R2 and R3. I've seen not recognized errors from R1 not being connected properly.

 And a picture may help.

 EDIT: Another question - is this a cable dac build or one using the mini-usb connector?


----------



## mfaughn

Stand alone cable dac

 picture? may get to that but then you'd all see just how badly I solder.

 Resistance is correct through R1,2,3.

 When powered:
 VDD = 3.3V
 VBus = 3.3V 
 VCCP = 3.3V
 Vcom = stabilizes at 2.2mV
 Vccl = 38.5mV
 Vccr = 5.6mV
 Voutl & Voutr = 2.2mV

 Second measuring (trust more):
 When powered:
 VDD = 3.3V
 VBus = 3.3V 
 VCCP = 3.3V
 Vcom = 3.2mV
 Vccl = 39.8mV
 Vccr = 12.4mV
 Voutl & Voutr = 3.2mV








  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Is this attached to something else (i.e like a Carrie)?

 I would re-check the resistors R1, R2 and R3. I've seen not recognized errors from R1 not being connected properly.

 And a picture may help.

 EDIT: Another question - is this a cable dac build or one using the mini-usb connector?_


----------



## cobaltmute

If it is a cable dac, i.e the usb cable is attached, are you sure D+ and D- from your USB cable are soldered to the right places? Reversing them will have Windows recognize the DAC but say it has malfunctioned.


----------



## mfaughn

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_If it is a cable dac, i.e the usb cable is attached, are you sure D+ and D- from your USB cable are soldered to the right places? Reversing them will have Windows recognize the DAC but say it has malfunctioned._

 

I've got green to D+ and white to D-. That is the USB standard color coding. I suppose it can't hurt to try swapping them.

 edit: that wasn't it either...


----------



## nullstring

have you tried reflowing the solder around the chips?

 I've heard that fix issues like this plenty of times


----------



## mfaughn

Quote:


  Originally Posted by *nullstring* /img/forum/go_quote.gif 
_have you tried reflowing the solder around the chips?

 I've heard that fix issues like this plenty of times_

 

yup, done that. also have ohmed out all the pins from the top of the chip to the edge of each pad. Next will be an attempt to ohm out from each active pin on the chip to where it connects on the board so that there is a trace between the test points. If that checks out then I think I'm going to bag it and try new ICs.

 Anyone know if those voltages looked reasonable? I found some other forum discussion on PCM2707 problems and their voltages where quite different than mine for some of those locations.

 Thanks to y'all for trying to help me out.

 -Michael


----------



## cobaltmute

Okay, a couple of more ideas:

 - from the 3.3V side of L3 to D+, what is your resistance (power off)?
 - from D+ to pin 23 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.
 - from D- to pin 22 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.
 - Check from D+ to D- to see if there is any shorts.

 As well, it would help if you gave us the full message of the error to understand if it is a communication error or a power error.

 If you check in Windows Device Managment, does it show any USB port being down after insertion?


----------



## cobaltmute

The voltages are all good. The ones that are low are that way as we are not powering any portion of the headphone amp portion of the PCM.


----------



## cobaltmute

Michael,

 Forgot to add, what are your C9 and C10?


----------



## mfaughn

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Okay, a couple of more ideas:

 - from the 3.3V side of L3 to D+, what is your resistance (power off)?_

 

1500 ohms

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_- from D+ to pin 23 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707._

 

22.2 ohms

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_- from D- to pin 22 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707._

 


 22.2 ohms

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_- Check from D+ to D- to see if there is any shorts._

 

2.73 megohms 

 D+ to pin 22 is the same
 D- to pin 23 is closer to 1.9 megohms

  Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_As well, it would help if you gave us the full message of the error to understand if it is a communication error or a power error.

 If you check in Windows Device Managment, does it show any USB port being down after insertion?_

 

I took the usb cable off for the moment and I'll have to put it back on to check for the verbatim message. I am 90% sure that it is a com error. Windows says the device is unrecognized and has malfunctioned. It shows up as a connected device and windows says there is no driver.


----------



## cobaltmute

mfaughn,

 All of your power readings are OK. All of your resistances are OK and match what I would expect.

 The only time I have seen comm errors is when the D+ and D- have been reversed. I learned that one the hard way as the error was on the PCB. I'm leaning away from this right now as your resistance checks are good.

 The other time that I have seen errors in Windows is due to power errors. These are usually due to the board pulling too much power. 

 My next tests are:
 - can you put a meter between the USB cable and the board and determine how much current it is pulling?
 - check around U1, C9, R8, the LED, L2 for any shorts.

 The exact error message and pictures are starting to become really important. All of us have done bad soldering so don't be embarrassed. As well, can you let us know what hardware you are using this with - PC, Laptop, netbook, directly attached or through a hub, etc. The more you give us the more we can help.


----------



## cobaltmute

I was just checking on the online BOM for the grubDAC listed in the first post and the fates have aligned and everything is in stock again for those few that may still be ordering parts.

 For those that have built it and lived with it for a while, any more comments? There may be some production boards coming in the future


----------



## blippster

Not sure if this was mentioned before, but perhaps you could modify the output vias to be slightly larger, to accommodate around 22 gauge wire? I've completed my three already, but for at least one had to trim the wires I was using as they were too thick to fit in.


----------



## Billyk

Hey thanks! Been waiting a while for Mouser and kinda forgot this one. I'll finally get to finish it. Thanks again!


----------



## ujamerstand

well, I've finished building one of these today, but ran into some snags. At first, the dac is recognized by the usb, but no music plays. Then the device shuts off completely. 
	

	
	
		
		

		
		
	


	




 TPS regulator was hot when touched, I think its burnt to a crisp. I've determined that there is a solder bridge in the tps regulators' pin 1 and 2 that caused this. After replacing the device with a spare, with no solder bridge, the device doesn't even get recognized by the computer. voltage reading over c7 is zero. How is this possible?! I've just switched to a new device! What kind of sacrifice do I have to prepare to get this thing working? =.=''


----------



## cobaltmute

We'll see what kind of sacrifice 
	

	
	
		
		

		
		
	


	




 So first check: Pin 1 of U1 to gnd (the pad with the via) - this should be ~5V as this is raw USB

 Then either end of L3 to gnd - this should be 3.3V.

 Use the GND of the outputs

 Also check from the GND beside the usb connector to gnd for output for resistance - this should be low. Check the resistance of L2 as well. If you shorted to ground, the ferrites may have gone as they can only handle so much current.


----------



## ujamerstand

Pin 1 of U1 to usb gnd returns 4.85V, and L3 to gnd returns zero. usb gnd to output gnd is low, around 68. the resistance of L2 to gnd is infinite, or are you talking about the resistance across L2? in that case its farely low at 1.8Ohms, I'm guessing I burnt the second regulator while soldering... Else L3 to gnd should have returned 3.3V. I will attempt to replace U1 with a third one tomm. In the main time, sacrifice will be tender stake tonight.


----------



## cobaltmute

For L2, I was talking about across the ferrite.

 Did you test USB ground to output gnd with a cable plugged in or not? If you did it with a cable in, can you try again with it not plugged in? The 68 ohm reading seems high. The only thing in line there should be a ferrite, which should give you very low resistance at DC.

 Try reflowing the reg before replacing it. As well make sure to clean it very well afterwards. Rinse with alcohol and blow with air to move the flux off the board or bloat with paper towel.


----------



## ujamerstand

The cable was not plugged in when I was testing the resistance yesterday. When I tested usb-gnd to output-gnd again today, the resistance reading is much lower, 3-4 Ohms under both plugged in and not conditions. I've ohmed out the pins of U1 and other devices, and there appears to be no cold joints. I've rinsed it with alcohol last night, even scrubbed it with a toothbrush. Any alcohol that might be there should have evaporated overnight. But the device still wouldn't show up in windows today. :s

 edit: huh, now the voltage readings at 1.8V. Oh, and it runs hot. I am now utterly confused.


----------



## ujamerstand

here are some pictures of the DAC:









 noticed the small 25V 1uF caps. They were hard to work with. Perhaps I mistaking placed something somewhere?


----------



## cobaltmute

power down and Ohm out L3 to ground. The reg getting hot makes me think that something is shorted somewhere as it has too much current passing through it.

 It also looks like you ordered 0805 instead of 1206 for some of the capacitors, when they should all be 1206.


----------



## ujamerstand

yes, since they were had the same value, and the one in the excel BOM wasn't available at the time of order, I've ordered those ones instead, I didn't know there would be a difference. Will do the measurements once I'm back in my workshop.


----------



## cobaltmute

I'm pleased to announce that the prototype boards are now available at Beezar





 tomb has also put up a grubDAC page at DiyForums.

 The board needed a good home for the future and I think Beezar provides that. Tom has done a bunch of work for this and lots of kudos to him. We're working on the final production board to which we've added a few nice touches, and as Tom has pointed out at Beezar, it should be out in a few months after we finish a few test runs to make sure we got it right.


----------



## Juaquin

That's awesome to hear! I'm sure Tom will take great care of them


----------



## Billyk

Most Excellent! I love Beezar, Tom is a great person to deal with. I am sure the design will flourish there.
 I have all I need to complete the one I have thanks to you heads up. I look forward to completing it soon.
 Happy New Year!


----------



## ujamerstand

Congratulations! tomb was really helpful when I was building my minimax. Glad to see that your design is in good hands!


----------



## luvdunhill

Cool! I see a production version rendering, but not many clues to the changes, besides the board shape and a few extra "black boxes" here and there 
	

	
	
		
		

		
		
	


	




 Care to clue us in?


----------



## tomb

Umm ... many thanks for the kind comments, guys. You guys are super-nice to say some of the things you have.
	

	
	
		
		

		
		
	


	




 However, the credit is due to cobaltmute for coming up with such a unique design that's the same size as the Bantam, but uses no output coupling caps.

 We're working on some special features that should assist in increasing future applications, but they're a somewhat radical departure from the prototype layout. So I'd rather not get into too many specifics until he does some more prototyping (me, too). We've got two more versions we've got to prove out in the pipe already and a third in planning.

 The existing prototype is a proven commodity for the time being.


----------



## cobaltmute

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_Cool! I see a production version rendering, but not many clues to the changes, besides the board shape and a few extra "black boxes" here and there 
	

	
	
		
		

		
		
	


	




 Care to clue us in? 
	

	
	
		
		

		
		
	


	


_

 

Knowing what changes I've done, all the information is in plain sight with a little work. 
	

	
	
		
		

		
		
	


	




 Once we know everything works the way we want it, we'll post the "official" list.

 At this moment, I'm very happy with what the end result will be.


----------



## Rooford

Just wanted to say thanks for putting this DAC together, it took 3 hours to build although I've not cased it yet. 

 So far I'm impressed! It sounds good from the off, in comparison to the Bantam DAC which sounded a little muddy to begin with. I guess the absence of capacitors in the audio output help.

 I'm driving an AMB M3 with the DAC. The DC bias of the DAC is 0.8mV after amplification it's around 0.7mV with volume at normal listening levels but turned to maximum volume it's around 7mV.

 Should I be worried about DC offset or am I being paranoid, I know it kind of defeats the purpose of using this particular DAC. Is it possible to use capacitors to de-couple the output and remove DC offset without ill effect?

 If so would using similar capacitance values to those used by the Bantam DAC work OK?

 I found this link by Tangent on input capacitors and wondered if it's relevant:
Input Capacitors for Headphone Amps

 Thanks,

 James


----------



## tomb

Quote:


  Originally Posted by *Rooford* /img/forum/go_quote.gif 
_Just wanted to say thanks for putting this DAC together, it took 3 hours to build although I've not cased it yet. 

 So far I'm impressed! It sounds good from the off, in comparison to the Bantam DAC which sounded a little muddy to begin with. I guess the absence of capacitors in the audio output help.

 I'm driving an AMB M3 with the DAC. The DC bias of the DAC is 0.8mV after amplification it's around 1.2mV at normal listening volume. Playing music at normal listening levels the AVG DC output is around 3.5mV which I guess is OK.

 However, turning the volume to 3/4 volume the average DC offset is 220mV which I believe is too high, the M3 website indicates anything > 5mV could damage headphones. Although I do not listen at that volume and I know it kind of defeats the purpose of using this particular DAC is it possible to use capacitors to de-couple the output and remove DC offset without ill effect?

 If so would using similar capacitance values to those used by the Bantam DAC work OK?

 I found this link on input capacitors and wondered if it's relevant:
Input Capacitors for Headphone Amps

 Thanks,

 James_

 

DC Offset is measured with the volume at zero (shorted inputs) and no music playing. Besides, only a _very_ high-quality meter can properly separate DC from a music signal.

 That means your total offset is less than 1.2mV, I believe, which is excellent.

 EDIT: Oops - sorry for taking so long to reply. Looks like you came to the same conclusion about trying to measure with music playing.


----------



## cobaltmute

Quote:


  Originally Posted by *Rooford* /img/forum/go_quote.gif 
_I'm driving an AMB M3 with the DAC. The DC bias of the DAC is 0.8mV after amplification it's around 0.7mV with volume at normal listening levels but turned to maximum volume it's around 7mV._

 

I'd say you're doing great. Amplifiers also amplify DC so having only 7mV at full on is quite tolerable. If you read Tangent's basic troubleshooting (Loud pop at turn on section), he talks about anything under 20mV as workable.

 Glad to hear it works and you like it.


----------



## Billyk

Finally had the time (and parts) to finish mine. Took me about 3.5 hours, very smooth build. I think I like SMD better than through hole... almost. When I snapped the tweezers with that 805 resistor and sent it flying onto a dirty blue and white carpet I was almost in tears. Found it so all is well. Powered up, was recognized, and made noise first time and it sounds darn good.
 I checked out the new site to get the build info and BOM. Looks great! I have one more Carrie proto after this one and think I will wait for the new rev. 
 Thanks for this!


----------



## ujamerstand

Good Job! My last 2 SMD soldering attempts has resulted in failure 
	

	
	
		
		

		
			





 I'll have to go back to debug my grubDAC when I got time.


----------



## cobaltmute

ujamerstand,

 Are you working under magnification? It helps immensely. Same for using flux.

 I just picked up one of these in 8x from Sayal for $5. Checking over a board is pretty easy - everything is so large


----------



## Billyk

Thanks man! Listening to it as I type sounds great with foobar and ASIO4all.

 Cobaltmute, that's a great idea; I'm going to get one. Now I wear two pairs 3.5 reading glasses. Gives me good enough for the work and I check it with a 10x magnifier.

 Flux, magnification, more flux, practice, a little more flux... SMD is quickly becoming my preferred building method. If I could only figure out how to stop sending those things flying when I pick them with the tweezers


----------



## ujamerstand

I've got a magnifier, never got used to using it. Instead, I'm using it as a third leg to stabilize the helping hands. But I do make sure I dab more than enough flux onto the pcb before soldering, it really helps with smd!


----------



## cobaltmute

The resistors are the most pain in the a** as they are flat. I find capacitors easy to get down. No caffeine is the answer. I also brace my arms on the table as I work. I open the cut tape so the part falls onto the board, and then align as necessary.

 I work with my face pressed into a magnifier light like this Sometimes it gets in the way as I try to solder, but then I just move everything until I can get it right.


----------



## Billyk

I am in my 50's so the old eyes just aren't what they used to be. I find the double glasses trick gives me the best vision for the least fuss. I do love the big magnifier though. 
 There is something so satisfying when you get one of those big chips done just right, 28 , 32 leads, so cool. I do the same with the single chips and dump them right on the board, those 805s tho... 
 I know I must be dense, but I just now figured out that the carrie / grub combo has no caps in the audio path. The only good cap in the audio path is no cap!
 Thanks for this great design, I am listening to it with my Mini^3, sounds great, gotta order those Carrie parts tonight.


----------



## keyid

finally cased up one of my carrie/grub combos! Sound great


----------



## cobaltmute

Cool casing!


----------



## Billyk

Nice case!
 Well I am bummed. Brought my freshly minted grub to work to listen to and it is now saying USB device not recognized. Drat. Getting 5.01 on the USB and 3.29 out of the reg. I must have damaged the 2707... I reflowed everything and checked for shorts and bridges. Any ideas?


----------



## keyid

if it was working before, then try on another computer.


----------



## cobaltmute

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Nice case!
 Well I am bummed. Brought my freshly minted grub to work to listen to and it is now saying USB device not recognized. Drat. Getting 5.01 on the USB and 3.29 out of the reg. I must have damaged the 2707... I reflowed everything and checked for shorts and bridges. Any ideas?_

 

You've re-flowed R1-3? The not recognized errors I've seen before are where the device is found, but something is wrong with the communications.

 Is this one with a Carrie board attached or not?


----------



## Billyk

Tried several computers XP and Vista, same error on all. On a fresh PC, one that has never had a 2707 plugged in before, said new device found, installing new device, device installed, then went to USD Device Not Recognized.

 Double checked R1,2,3 reflowed, ohmed out from USB pins through R3 R2 to the via points near C3 got 22.8 ohms on each, got 1.502k on R1 to the leg of C10 from the USB pin
 Thanks!


----------



## cobaltmute

So this was a fully function grub brought to work and now it fails?

 As I asked - just grub or grub + Carrie?

 Do you have any messages in Event Viewer? What does computer management say (also check in the USB portion to see if any ports are being shutdown)?

 Is it failing in case or out of case? Cable DAC?


----------



## Billyk

Fully functional and sounding great.
 Stand alone (sorry forgot that)
 No case, taped to a bit of pink static foam to protect the bottom. Wired to a 3.5mm jack. Not a cable type, has USB plug mounted.
 Did not see any errors or warnings in the event logs. USB states unknown device, power draw 100ma


----------



## cobaltmute

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Fully functional and sounding great.
 Stand alone (sorry forgot that)
 No case, taped to a bit of pink static foam to protect the bottom. Wired to a 3.5mm jack. Not a cable type, has USB plug mounted.
 Did not see any errors or warnings in the event logs. USB states unknown device, power draw 100ma_

 

Remove the static foam - it is conductive.

 If the USB is stating 100mA you are ok. If it actually measured, that is bad. The PCM2707 will report 100mA use to the host, but the grubDAC doesn't draw that much.


----------



## Billyk

Yeah, reporting not measured.
 Non conductive, pink foam. Removed it anyway. No love.
 Must have fried the chip somehow. It is very dry here, static could be the culprit. Shoulda cased it but did not have one and wanted to play with it. When/if I have some spare $$ I'll get another 2707, Mouser is out until April, would a 2706 work?


----------



## cobaltmute

Without being able to see the data stream, yeah it looks like it may be a PCM2707 issue.

 As for using a PCM2706, it is reported as being compatible for the PCM2707, but I personall haven't tried it - yet. That will be hopefully within a week.


----------



## Billyk

Thank you much. I appreciate all your time and input.


----------



## gurusan

This looks like a really great project....thanks so much for all the effort.


----------



## gurusan

I have just soldered together the grubDAC, but I bridged 2 pins on the PCM2706 DAC and can't seem to get it right! Any tips?

 I have purchased some .8mm solder braid and a new solder tip as mine is crapola but those won't be here for a day or 2. 

 Anyway it looks awesome lol, soooo tiny. I just wish I could fix this solder bridge!


----------



## pistolsnipe

lots of flux, wipe your tip off on a damp sponge then draw it across the bridge from the chip out, holding the tip as flat to the pins as you can (ie connecting to as many as possible), done in a jiff. i always get bridges on smd qfps, and they come right off


----------



## cobaltmute

That looks like a lot of solder on that bridge, but you can try pistolsnipe's technique.

 I always get bridges. I drag down the pins to the pads to get the bridge off the pins and maybe spread it out on the pins. I'll also try dragging the bridge across the pads to spread out the amount of solder on each pad (again drag down the pins to the pad). Last resort when it won't go away is to use braid.


----------



## descendent87

Can you buy the PCB from any UK sites? Just wondering as delivery would be quicker.


----------



## cobaltmute

The only place that will have the board will be Beezar.


----------



## gurusan

Well I used the flood and suck method to repair the solder bridge and it worked! The USB works great and sounds lovely! There is some background noise noticeable at higher amped volumes which changes when I move the mouse and such though. Anything I can do about this?


----------



## cobaltmute

What are you driving? Is it headphones direct or an amp? And what kind of headphones?


----------



## keyid

see if you still hear the sound after you turn off your monitor.


----------



## gurusan

Monitor has no effect on the sound


----------



## cobaltmute

Is your mouse a USB mouse? Could be an internal hub is sharing power.


----------



## gurusan

Yes it's a USB mouse. I have a decent 5V linear supply here that I can try. Do I need to desolder the USB power pin to try out the external PSU?


----------



## cobaltmute

I wouldn't try and use an outside power supply. Yes you could desolder the power pin on the USB jack and attach the outside power supply, but per the spec sheet, the HOST pin of the PCM2707 is supposed to go high when attached to the bus. That will happen before as the way I did the board, it is attached to power (with no switching). So it may or may not work. I would try some other USB ports first.

 Also curious what kind of amp you are running and at waht gain?


----------



## joneeboi

Anyone have two spare PCM2707s on them?


----------



## Andrew_H

Just noticed the Wolfson WM8524GEDT is on back-order at Mouser.
 According to them, backordered items are free delivery to UK, but when I try
 to buy, it still comes up with a £12 ($19) delivery charge !
 Anyone had any experience with this ?


----------



## Juaquin

I think they mean that if something is backordered, they'll sent everything else (for the appropriate fee) and then when they get the other items they'll send them out free of charge. I could be wrong but I can't imagine why they would ship everything for free just because something is backordered.


----------



## keyid

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_I wouldn't try and use an outside power supply. Yes you could desolder the power pin on the USB jack and attach the outside power supply, but per the spec sheet, the HOST pin of the PCM2707 is supposed to go high when attached to the bus. That will happen before as the way I did the board, it is attached to power (with no switching). So it may or may not work. I would try some other USB ports first.

 Also curious what kind of amp you are running and at waht gain?_

 

though it would be interesting to see/hear improvements with battery power w/ grub & carrie. How high does HOST pin go cant be more than what usb can provide 5v 500ma?


----------



## Rooford

Quote:


  Originally Posted by *Juaquin* /img/forum/go_quote.gif 
_I think they mean that if something is backordered, they'll sent everything else (for the appropriate fee) and then when they get the other items they'll send them out free of charge. I could be wrong but I can't imagine why they would ship everything for free just because something is backordered._

 

Yes, that's right quote from mouser below. I'm not sure whether they do this for international orders though:

_In an effort to reduce shipping costs to our customers we pay for the first pound of UPS Ground or FedEx Ground on backordered shipments if there has been one or more previous shipments on the order. If your order is not scheduled to ship UPS Ground or FedEx Ground or if the freight is being billed directly to your UPS or FedEx account number and you would like us to update your ship method so that you can take advantage of this service, please let us know by replying to this e-mail and specifying how you would like it shipped._


----------



## Andrew_H

Clear as mud !
 It seems the `free shipping` refers only to the back-ordered items when a multiple order is made.
 So, if, like me, your only after 1 item (on back-order) you have to pay $19 postage for a $2 part that could take weeks/months to be despatched.
 I`ll keep looking.


----------



## cobaltmute

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_though it would be interesting to see/hear improvements with battery power w/ grub & carrie. How high does HOST pin go cant be more than what usb can provide 5v 500ma?_

 

The HOST pin should be attached to Vbus (5v) when the USB cable is attached. From the datasheet:
  Quote:


 Host detection during self-powered operation (connect to VBUS). 
 

So you can jumper it right to the 5V from the USB cable. You'd need to ensure that pin 4 is grounded (PSEL). On the production boards PSEL will be high to tell the PC that the board could draw up to 500ma (when attached to a Carrie or other item).


----------



## cobaltmute

As we are really close to sending the board out to production:




 Revision F = Final 
	

	
	
		
		

		
			





 So what changed from the original proto to now?

 The board layout changed. This was driven by a couple of items. First, to make it compatible with the Bantam, the output holes were adjusted to nearly match the Bantams, but the grubDAC's were kept on 0.1" centers. The mounting holes were moved to match the Bantam's exactly. The LED was moved to be near the USB connector.

 You may notice that there are cutouts on the board as well. These are there so the board can fit into a Hammond 1551H case without modification to the board or the case. With the right choice of electrolytics, the board will fit in the case and mount cleanly on the PCB mounts. All you have to do is cut slots in the case for your input and output wiring. Makes it very simple to build a cable dac.

 Yes, with the physical changes, the board still does fit into a 1455C case for mounting with the Carrie.

 Schematic-wise, there were two changes. First, a change was made to the post-DAC RC filter. In the original, a SMT ceramic capacitor was spec'ed. The new default is a Wima film capacitor, but the option still remains to the ceramic on the bottom of the board. The second change has to do with the timing for the PCM2707. With the layout changes, I felt that the crystal would have to be placed too tight to the PCM2707 to allow a user to work on the chip if required. To move the crystal around, I thought there would be problems with trace lengths so I changed the crystal for an oscillator. It gets fed with its own RC filtered supply from the rest of the board.

 These last refinements have taken a while to get down, given that every change has taken 3 weeks for a BatchPCB run, but the production board is finally here. Now we just have to wait to get it made.


----------



## tomb

Yep - hope to order the production versions this week.
	

	
	
		
		

		
		
	


	




 I built a couple this weekend using the latest prototype that Erik pictures above. These were built with the PCM2706, a pin-compatible alternative to the PCM2707. They sound great - lots of detail, great midrange and a surprisingly impactful, resolute and tight bass. It's really a wonderful little DAC!!











 As Erik noted, these fit the little Hammond 1551HTBU perfectly, only requiring a slot to be cut on both sides under the lid for the wiring. Once the CableDAC is assembled with cable and RCA outputs, simply lay the assembly into the Hammond box, screw down the two #2 screws and attach the lid. Since the box is translucent, the LED shines through without having to pop a hole in the lid.

 Kudos to Erik for coming up with the idea for the case - also for his patience as I pestered him to death to make the changes to fit the case so nicely. We'll probably be ordering them from Hammond in volume with the slots pre-cut on the sides for the wiring - so you'll have nothing to do but screw the board in, and screw on the lid.


----------



## ovrclkd

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yep - hope to order the production versions this week.
	

	
	
		
		

		
		
	


	


_

 



 Looks like I'll wait Tom ....


----------



## Llama16

... and I was hoping to stop ordering stuff from out of europe for a while


----------



## pistolsnipe

are these going to be priced the same as the proto boards?


----------



## tomb

Quote:


  Originally Posted by *pistolsnipe* /img/forum/go_quote.gif 
_are these going to be priced the same as the proto boards?_

 

No, but when they're already priced at the cost of potato chips, we think you'll agree that the increase will still be trivial.


----------



## tomb

BTW, there was a question in the Pics of Your Builds thread - the reason I didn't use any cable ties for strain reliefs was that the slots weren't deep enough to clear the lip of the lid. So in each case, the cables are locked in place with a screwed-down lid. When we go to production and if we stock machined cases, it'll be prudent to tie a couple of cable ties on the case interior side of each cable exiting the box - just so a jerk doesn't pull the them out of their pads.


----------



## cobaltmute

I should note that I tried grommets in the slots for a Bantam I built. It doesn't work very well. You could use silicon sealant to seal the wire in the slot. If you were to do this, you'd have to let it dry thoroughly before closing the lid. Silicon seal outgases acetic acid during drying.


----------



## Postal_Blue

Just wanted to chime and say there is another working GrubDac in the world, i have not had time to do anything other than verify it works. It will be strapped to a carrie as soon as the group buy board finds its way to me. On a side note, anyone thinking on buying a Hakko 936 DO IT, best decision i have made in my foray into DIY.


----------



## cobaltmute

A little bird told me that it found some Grubs at Beezar


----------



## Billyk

Wow that looks great!!!
 Now if I could only get some 2707s I would be in heaven!


----------



## cobaltmute

'dere be plans


----------



## ujamerstand

Those are some sexy looking boards cobaltmute!


----------



## MASantos

If the kits were available I'd get one, this seems interesting and would love to compare it to the Alien DAC! 

 Any ETA on the kits?


----------



## tomb

The intent is for Beezar to sell kits - in the GrubCableDAC version.
	

	
	
		
		

		
		
	


	




 However, as you all probably know, the availability of PCM2706/7's is quite bad.
	

	
	
		
		

		
		
	


	




 I'm working on a solution that will last quite awhile, but it'll be mid-to-late April before I can get a sizable quantity.

 I'm going to try to include everything, though - RCA plugs, wire, and even heat shrink.
	

	
	
		
		

		
		
	


	




 BTW, just to repeat - those notches in the PCB's fit the Hammond translucent blue 1551HTBU exactly. So, that'll be the case we'll be using - just as with the very first one that cobaltmute made and the two I made a couple of weeks ago.

 EDIT: Also, as cobaltmute emphasized before, they'll work fine with a mini-USB in the Carrie or the MAX V1.2.


----------



## Billyk

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_'dere be plans 
	

	
	
		
		

		
		
	


	


_

 

That would be something! I have all the parts for 4 proto and one with a bum 2707. I do have 6 on backorder at Mouser... It's holding up my carrie builds!


----------



## cobaltmute

I will note that the BOM did change a bit from the prototype to production. We shrunk some of the capacitors to 0805 and the crystal has been changed to an oscillator. You'd need to verify what parts you have that can carry forward.


----------



## cobaltmute

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_EDIT: Also, as cobaltmute emphasized before, they'll work fine with a mini-USB in the Carrie or the MAX V1.2._

 

Why limit to the Carrie or MAX V1.2? At the price/performance point, you should put one in everything.


----------



## Lil' Knight

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_The intent is for Beezar to sell kits - in the GrubCableDAC version.
	

	
	
		
		

		
		
	


	


_

 

Would be great if you could offer the pre-soldered chip service


----------



## tomb

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Why limit to the Carrie or MAX V1.2? At the price/performance point, you should put one in everything. 
	

	
	
		
		

		
		
	


	


_

 

Quite true! I need to start thinking outside of the PCB's-specifically-designed-for box.
	

	
	
		
		

		
		
	


	







  Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_Would be great if you could offer the pre-soldered chip service 
	

	
	
		
		

		
		
	


	


_

 

I don't know about that one. Besides, IMHO, both of these chips (PCM2706/7 and WM8524) are easier to solder than the PCM2702.


----------



## Billyk

Quote:


  Originally Posted by *cobaltmute* 
_Why limit to the Carrie or MAX V1.2? At the price/performance point, you should put one in everything._

 

No kidding! I have a whole list of folks to get them to. Cannot think of a better way to introduce my music sharing friends to great sound!


  Quote:


  Originally Posted by *Lil' Knight* 
_ Would be great if you could offer the pre-soldered chip service_

 

I have come to prefer SMD, even with my old (54) eyes! One thing though, I find I have to be in the right "place" to do it. If I am struggling, I put it away for another day, that has gotten rid of a lot of my frustrations. I can really move when I am in the mood the last Bantam took just under 30 minutes!!


----------



## cobaltmute

Billyk is right - you have to be prepared to do SMD. Do not rush, do not hurry and do not panic. If you feel rushed or frustrated, you need to step away.

 It takes me about 2 hours to do a grubDAC. I'm slow and methodical. And they work right the first time, every time.


----------



## Billyk

Quote:


  Originally Posted by *cobaltmute* 
_It takes me about 2 hours to do a grubDAC. I'm slow and methodical. And they work right the first time, every time._

 

Well I will admit that the 30 minute time was for the actual soldering, I had spent prolly more than 30 minutes setting it all up, laying out the parts, etc. So come time to solder, I just had to pickup the part and go! And of course I did not count the 20 minutes it takes to find the 0805 chip that I shot across the room by squeezing it too hard with the tweezer 
	

	
	
		
		

		
			




 Slow and careful is the right way to do it, my biggest problem is the packaging, so if I lay it all out before hand, labeled on a sheet or two of paper, with the BOM and schematic it makes it easier.


----------



## ziplock

Going to give this one a go. 

 Boards and parts ordered. I'm looking forward to the build.

 I think I'll put a few pieces on at a time while I wait for the 2707s to become available. No reason to rush.

 Anybody else building one?


----------



## Billyk

I will be as soon as I finish the four proto versions. Just need those 2707s!


----------



## tomb

Remember to check on the PCM2706's. Those work, too, and are arriving sooner at most places, I believe.


----------



## cobaltmute

Quote:


  Originally Posted by *ziplock* /img/forum/go_quote.gif 
_I think I'll put a few pieces on at a time while I wait for the 2707s to become available. No reason to rush._

 

If you're going to do that be very careful - you want to make sure that you do things in an order that you don't make it difficult to solder down the PCM2707. I would do the bottom chips only if I were to do that.


----------



## tomb

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_If you're going to do that be very careful - you want to make sure that you do things in an order that you don't make it difficult to solder down the PCM2707. I would do the bottom chips only if I were to do that._

 

Agreed! When I put my two together for the first time, I chose the PCM2706/7 as the very first item to solder - even before the WM chip. It seemed to work best that way.


----------



## ziplock

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_If you're going to do that be very careful - you want to make sure that you do things in an order that you don't make it difficult to solder down the PCM2707. I would do the bottom chips only if I were to do that._

 

Right. I'll probably save most of the through hole for last. Possibly L2 as well.

 It just depends on how it looks when I get the board.

 The DAC chips look like a piece of cake to solder down. Rather large pitch, no? .65 and .8mm


----------



## cobaltmute

The PCM2707 being TQFP-32 seems to be about the same as putting down a SOIC chip. Bit more work in alignment due to the pins on the four sides. the WM8524 I find not too bad as well.

 I would definitely leave the through hole for last. Putting that in before the SMT stuff can lead to issues.

 My basic plan for doing a grubDAC:
 PCM2707
 WM8524
 XO
 Then top side SMT R and C
 Bottom side TPS regulator
 Bottom side SMT R and C
 Through hole R 
 Through hole C

 When doing R and C parts, I do the blob of solder and then slide the part in method. I always do the non-ground plane side of the part first as the ground plane sucks heat and makes it hard to align the part. I also look at the board and plan what order will make sure I don't "bury" an end of a part making it hard to solder afterwards


----------



## netsky3

I have a little question: between the grubdac and the bantam wich is the better one?
 Where i can find the specs of them?


----------



## cobaltmute

There is this for specs on the BantamDAC. To my knowledge no-one has done a RMAA on the grubDAC. I would do it but I do not have a good input source that I can test with.

 They sound different as the BantamDAC is AC-coupled (capacitor in-line). I'll let others comment on the difference in sound. Both are in-expensive though and if you build both you can have a good idea for yourself.


----------



## netsky3

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_There is this for specs on the BantamDAC. To my knowledge no-one has done a RMAA on the grubDAC. I would do it but I do not have a good input source that I can test with.

 They sound different as the BantamDAC is AC-coupled (capacitor in-line). I'll let others comment on the difference in sound. Both are in-expensive though and if you build both you can have a good idea for yourself. 
	

	
	
		
		

		
		
	


	


_

 

Thank you.
 I'd like to know more opinions about the sound differences


----------



## antonyfirst

Which is the smoother one between the two?
 What does the fact of having inline capacitors imply (against not having them)? Warmer/less trebly sound? Or the other way around?


----------



## cobaltmute

Quote:


  Originally Posted by *antonyfirst* /img/forum/go_quote.gif 
_Which is the smoother one between the two?
 What does the fact of having inline capacitors imply (against not having them)? Warmer/less trebly sound? Or the other way around?_

 

The point of having the capacitors inline on the BantamDAC is that the PCM2702 output mid-rail (~2.5V) DC and the capacitor blocks that. 

 As for the sound of the capacitor? That is a religious debate. Black Gates, Vitaman Q, Wima, Silmic, Cerafine, Muse, Solen, Vishay Roederstein, etc all have been said to have different sounds. It comes down to personal preference to determine which one you like.

 The grubDAC doesn't need a DC blocking cap. The WM8524 uses a charge pump to generate a negative rail and outputs a low offset signal. So you are trading the capacitor for a technology to create the negative rail.

 So the grubDAC and the BantamDAC are different beasts in the output stage and they sound different. Some people have commented already in this and the Carrie thread, so you can get some opinions here and there. A few more vocal builders would help out a bit in this regard


----------



## Juaquin

Well no capacitors means you don't have bass roll-off. That's not a problem with the Bantam anyways, though. And of course, if you believe capacitors audibly color sound there's that too.


----------



## netsky3

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_The point of having the capacitors inline on the BantamDAC is that the PCM2702 output mid-rail (~2.5V) DC and the capacitor blocks that. 

 As for the sound of the capacitor? That is a religious debate. Black Gates, Vitaman Q, Wima, Silmic, Cerafine, Muse, Solen, Vishay Roederstein, etc all have been said to have different sounds. It comes down to personal preference to determine which one you like.

 The grubDAC doesn't need a DC blocking cap. The WM8524 uses a charge pump to generate a negative rail and outputs a low offset signal. So you are trading the capacitor for a technology to create the negative rail.

 So the grubDAC and the BantamDAC are different beasts in the output stage and they sound different. Some people have commented already in this and the Carrie thread, so you can get some opinions here and there. A few more vocal builders would help out a bit in this regard 
	

	
	
		
		

		
			



_

 

 Quote:


  Originally Posted by *Juaquin* /img/forum/go_quote.gif 
_Well no capacitors means you don't have bass roll-off. That's not a problem with the Bantam anyways, though. And of course, if you believe capacitors audibly color sound there's that too._

 

Thank you


----------



## tomb

Cobaltmute is being diplomatic and I appreciate his efforts.
	

	
	
		
		

		
		
	


	




 However, netsky3 - remember when I said that hopefully one should find a proportionate increase in sound quality with increase in price? The GrubDAC PCB is twice as expensive as the BantamDAC PCB. I'll leave it at that, except for commenting on capacitors in a general sense -

 There are good audio capacitors and there are not-so-good audio capacitors. Some might even be called great in their sound. However, considering equal circuits behind them, there is no capacitor that sounds as good as not having a capacitor at all. The question, of course, is whether one circuit topology is better enough to overcome the handicap of having capacitors in the signal path when compared to a different circuit that doesn't use them. For instance in some tube amps, it's possible that the circuit is outstanding enough that the fact there are capacitors in the signal path is not enough to detract from its performance when compared to other topologies.


----------



## netsky3

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Cobaltmute is being diplomatic and I appreciate his efforts.
	

	
	
		
		

		
		
	


	




 However, netsky3 - remember when I said that hopefully one should find a proportionate increase in sound quality with increase in price? The GrubDAC PCB is twice as expensive as the BantamDAC PCB. I'll leave it at that, except for commenting on capacitors in a general sense -

 There are good audio capacitors and there are not-so-good audio capacitors. Some might even be called great in their sound. However, considering equal circuits behind them, there is no capacitor that sounds as good as not having a capacitor at all. The question, of course, is whether one circuit topology is better enough to overcome the handicap of having capacitors in the signal path when compared to a different circuit that doesn't use them. For instance in some tube amps, it's possible that the circuit is outstanding enough that the fact there are capacitors in the signal path is not enough to detract from its performance when compared to other topologies. 
	

	
	
		
		

		
		
	


	


_

 

thanks for your explanation


----------



## luvdunhill

I don't suppose there is a Beezar mailing list? 
	

	
	
		
		

		
		
	


	




 Auto notification when kits are available would be pretty sweet!


----------



## netsky3

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I don't suppose there is a Beezar mailing list? 
	

	
	
		
		

		
		
	


	




 Auto notification when kits are available would be pretty sweet!_

 

uhm...but in the beezar there isn't a complete kit for a grubdac, right?
	

	
	
		
		

		
		
	


	



 I've seen only the pcb


----------



## cobaltmute

Back a few posts...

  Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_The intent is for Beezar to sell kits - in the GrubCableDAC version.
	

	
	
		
		

		
		
	


	




 However, as you all probably know, the availability of PCM2706/7's is quite bad.
	

	
	
		
		

		
		
	


	




 I'm working on a solution that will last quite awhile, but it'll be mid-to-late April before I can get a sizable quantity._


----------



## rds

Quote:


  Originally Posted by *Juaquin* /img/forum/go_quote.gif 
_Well no capacitors means you don't have bass roll-off. That's not a problem with the Bantam anyways, though. And of course, if you believe capacitors audibly color sound there's that too._

 

Keep in mind that a servo using a negative rail created by a charge pump will also "color" the signal. Whether the distortion is audible or better/worse than using output caps is a relative question.


----------



## netsky3

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_Back a few posts..._

 

ops...sorry


----------



## nullstring

EDIT: retracted.

_This post was me asking cobaltmute if I could get his source files in order to attempt to add the things I need in order to add SPDIF to the design.

 Tomb has pointed out that my request was not appropriate, and I will communicate with cobaltmute directly concerning this. _


----------



## tomb

Quote:


  Originally Posted by *nullstring* /img/forum/go_quote.gif 
_<snip>

 In any case, I can't seem to find layouts, schematics.. or anything for the production version.. are you not planning on releasing them?_

 

GrubDAC (grubDAC website)
 I can't speak for cobaltmute, but please note the key word, "production." It implies that cobaltmute's extensive prototyping, testing, and modification period is over.
	

	
	
		
		

		
		
	


	




 Quote:


 Would it be possible for me to get your source files so I can take a gander at making these changes? 
 

Again, not trying to speak for cobaltmute, but please ask yourself - does AMB supply source files to anyone for the B22, Mini3, Gamma 1 or 2? Does Tangent or Runeight or Dsavitsk or cetoole for any of their designs? Beyond that, most of these designers use software that is not free in order to meet the for-profit legal requirements.

 Just some things to think about for a bit.
	

	
	
		
		

		
		
	


	




 Maybe you should try PM'ng him.


----------



## nullstring

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Again, not trying to speak for cobaltmute, but please ask yourself - does AMB supply source files to anyone for the B22, Mini3, Gamma 1 or 2? Does Tangent or Runeight or Dsavitsk or cetoole for any of their designs? Beyond that, most of these designers use software that is not free in order to meet the for-profit legal requirements._

 

To be honest, I thought that when asked, any of these people wouldn't mind supplying their source files for others who want to take their work in a different direction. 

 For instance, I was under the assumption that joneeboi had used AMB's mini3 source files in the creation of the carrie.
 However, I could be quite wrong about all of this.

 I'm not quite sure what the problem would be. It's obvious why one would want to retain copyright over their own design, but I don't see a big issue in allowing another member of the community to make additions to your work under the assumption that the original creator retains full copyright.


 On another note, I took the production pictures and put them into photoshop and have found just where everything could be easily added inorder to do what I want to do.
 I took the two pictures and layered them ontop of each other, and they the holes were -exactly- matched up. I don't know if it was by design or just luck, but it was pretty cool.


----------



## tomb

Quote:


  Originally Posted by *nullstring* /img/forum/go_quote.gif 
_<snip>
 For instance, I was under the assumption that joneeboi had used AMB's mini3 source files in the creation of the carrie.
 However, I could be quite wrong about all of this._

 

Yes, if I'm not mistaken, Joneeboi's design is completely his. However, because the underlying circuit design was AMB's, that's why AMB gave his permission for a Group Buy (Head-Fi rules - no profit), but not to openly sell the Carrie otherwise.

 I could be wrong, too - but that's my memory of the chain of events.
	

	
	
		
		

		
		
	


	



  Quote:


 I'm not quite sure what the problem would be. It's obvious why one would want to retain copyright over their own design, but I don't see a big issue in allowing another member of the community to make additions to your work under the assumption that the original creator retains full copyright. 
 

Again, you need to contact cobaltmute personally about his opinions regarding this, but there are very few cases in this world where you can take someone's proprietary work and modify it for your own purposes. Pete Millett is one large exception in this community, but he has plenty of his own designs that are not even shared in terms of layouts or schematics (refer to TTVJ for examples).

 As for source files, those are the keys to the kingdom, so to speak, and in a digital world are the same as sharing software. In some cases, that's viewed as OK, but in other situations it's viewed as a crime.

 I'll stop commenting on it, though, and let you contact him. He may not have an issue with it under certain circumstances. Please don't take offense - I just thought perhaps you should consider more carefully before asking something like this on a public forum.


----------



## Billyk

Hi folks! An email came through showing activity in this thread....
 How is the schedule for the 2707 chips? Still on track?
 Thanks!!


----------



## nullstring

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Please don't take offense - I just thought perhaps you should consider more carefully before asking something like this on a public forum.
	

	
	
		
		

		
		
	


	





_

 

It's quite alright.
 I guess that I was under a very different assumption about how the community works. Everyone is so free and easy about posting their layouts, schematics, and even explaining what and why things were done that I didn't think that this would be an issue.

 I am an advocate of open source software. When there is a part of an application you would like to see changed and isn't getting added for one reason or another, it's a very appropriate response to just add it yourself.

 I was under the assumption that the diy audio community was very similar. It makes sense to not release source files publically and to retain copyright of your work, so that you don't have issues with people trying to make money of it; 
 I thought that was the reason source files weren't publically available.

 Again, it seems I was under a different assumption, and I've made an ass out of you and me (Ok, really just me.)

 Thanks Tomb. I will send cobaltmute a more formal message via PM.


----------



## Juaquin

The schematic and layout are both available on the Grub website. Now that the design work is done, it would be relatively simple to copy the schematic in Eagle, make your modifications, and build a board out of it. If cobaltmute supplied the schematic file all it would do is allow you to shortcut a couple hours work, and you're going to have to redo the board layout anyways. 

 Since the schematic is made freely available I believe you're welcome to do with it what you wish, as long as it's for personal use. If you were to do a group run or post detailed schematics you would probably want to get blessings first, since it wasn't originally your idea.


----------



## nullstring

hrm, since the pictures on the grubdac on the website weren't up to date, somehow I assumed that the layouts and schematics wouldn't be either.. but it seems they very much are >_< I guess I'm 0 for 2.


 I don't have to redo the board layout, because the change I want to make can simply be added to the current layout. Nothing needs to be moved around.
 EDIT: I've used photoshop to add the additions I want to the layout. With cobaltmute's permission, I'll post them.
 It really is a few simple changes.


----------



## rds

I may be wrong here, but I don't think the reticence to supply layout files is for economic reasons. Personally I wouldn't do it because it introduces an ambiguity between something that is (presumably) well tested and carefully designed and another very similar looking board that may or may not be.

 If there are 10 different boards out there that look nearly identical with slight variations that makes things confusing for DIYers who may not know much about circuitry. To me it's about quality control.
 Imagine the headaches for the designer who has to try to assess whether variations on her/his board have compromised the performance.

 There is one other thing: when you spend a large number of hours designing and laying out a PCB you may not feel good about having other people modify it.


----------



## cobaltmute

As I did read the original request earlier, but did not have time to respond and there is much other information brought forth since, I'm going to comment here.

 There is three large parts to a project such as the grubDAC: the schematic capture, the BOM and the PCB.

 The schematic tells you what is going on. Tells you what parts are connected to what. In the case of the grubDAC, I was able to start from an existing schematic, so it was fairly easy to do this portion.

 The PCB is really where the real work is. You're trying to fit parts to the PCB size. This process of doing the PCB also drives the BOM as you are trying to get certain size parts to fit in certain areas. You may have to tweak the value of a part to get the footprints you want.

 Compare the two following pictures:







 There was a lot of work to get from the one board to the next - I have about 15 iterations in my files. That is why it took about three months of working with tomb to get the board into production at Beezar. Doing things like making sure it will fit in all the cases that we want it to, that every external corner of the board is curved, moving vias a mil at a time to ensure that they are placed in exactly the right spot, adjusting thermal reliefs to ensure that currents are going the best path, etc.

 Now about releasing information to the community:

 Schematics are released as they are important for builder to build and troubleshoot the boards that they are working on. amb also notes that they are great source of information to learn how a circuit works. I have learned tons by looking at the schematics of others. Take a look at a PCM2707. There really is a limited number of ways that you can implement it as a USB to I2S converter. So many peoples designs will look similar. The onus is for the designer however to understand the chip. You can carbon copy someone else's design or you can read the datasheet and figure it out yourself.

 PCBs are again something that is "released". A designer lays out a board and then releases it to the community as a finished PCB. You see it for yourself. You can see how the traces are laid out and the footprints of the parts that were chosen.

 I initially built the grubDAC for my use as a present to my dad. Turns out that some of you like the extra boards I had run. I can honestly say that if tomb hadn't offered to carry the boards at Beezar, I'd have likely killed the project after the protoboards as I'd move onto the next thing that I'd want to build. That has nothing to say about how I feel about the grubDAC (which is that it amazing DAC for its simplicity), but more to say about the fact that I personally don't want to have to do the work of selling PCBs day to day.

 rds is right as well. I'm willing to support a board that is designed by me and provided by me. I've built them and I know they work. If someone takes a board of my design, does slight mods to it that do not work and passes it off as a grubDAC, that is not good for me or my boards. 

 As an illustration of that last point, you may want to read this (especially point 3 of the first post): DIYHiFi.org &bull; View topic - "What's all this IP stuff about, anyway?"

 There are those that will take a posted design/schematic/board and try and make money of it and leave the support to others. I'm not really cool with that.

 There is another thing as well. Beezar is setting up to make kits and ensure availability of parts for the grubDAC. This take money and not a small sum of it. While this really is not my expense, I'd like to continue dealing with Beezar and am not going to do anything to jeopardize that relationship.

 Every designer has his own reason for doing things in a certain way. I highly doubt that you will get a board file out of any designer for any active design. There are a number of designs that have been "given" to the community (see Headwize), but you still have to do your own PCB for most of them.

 So my take is that while a design is active with me, I'm going to keep the files private for many of the reasons noted above. I'll support, help develop it and make it better. If I take a design and consider it dead, I might just give all the files out to the community. Why not? Let others get into the details and learn from what I have done. But if I "dead" a project, it will be dead to me - no support, no involvement for some of the same reasons noted above.

 At this point, the grubDAC is not dead, so the files stay with me. Doesn't mean I won't work with others for interesting ends.


----------



## Billyk

+++

 Thanks for a great design!


----------



## ziplock

Another GrubDAC lives and it sounds excellent!

 Thanks for sharing the design.


----------



## Billyk

Two more live, thanks to a heads up from a friend. One was from scratch and one was a repair where the 2707 went bad... Boy these thing make good music!

 Cobaltmute it was the 2720 that went bad, if you recall my cry for help a few months back, just thought I would let you all know.


----------



## redfish-bluefish

Are there any plans at Beezar to offer the hard-to-find GrubDAC parts a la carte in addition to the kits. For those who might want to add one to another build like the Max, but not need case, cable etc. Of course, I just realized that having those laying around as extras for other DIY might not be a big deal anyway. Still, just curious.

 Thanks!
 1,2
 red-blue


----------



## cobaltmute

My understanding at this point is that Beezar has plans to take care of all builders


----------



## tomb

Yes, cobaltmute and I worked out two options for kits that Beezar will be offering -
 1) Kit to populate the basic PCB with a mini-USB connector, no outputs, no case. This will work out best for those of you building a grubDAC for the MAX V1.2 and the Carrie.
 2) Kit with full parts, including wire, heat shrink, RCA plugs, USB pigtail, and case, for a grubCableDAC. IMHO, this would be the preferred stand-alone source option.


----------



## redfish-bluefish

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yes, cobaltmute and I worked out two options for kits that Beezar will be offering -
 1) Kit to populate the basic PCB with a mini-USB connector, no outputs, no case. This will work out best for those of you building a grubDAC for the MAX V1.2 and the Carrie.
 2) Kit with full parts, including wire, heat shrink, RCA plugs, USB pigtail, and case, for a grubCableDAC. IMHO, this would be the preferred stand-alone source option.



_

 

Rad. 
	

	
	
		
		

		
		
	


	




 Thanks! This makes an already outstanding project plan even better!


----------



## netsky3

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yes, cobaltmute and I worked out two options for kits that Beezar will be offering -
 1) Kit to populate the basic PCB with a mini-USB connector, no outputs, no case. This will work out best for those of you building a grubDAC for the MAX V1.2 and the Carrie.
 2) Kit with full parts, including wire, heat shrink, RCA plugs, USB pigtail, and case, for a grubCableDAC. IMHO, this would be the preferred stand-alone source option.



_

 

Great Idea


----------



## ziplock

Should this little DAC sound so good? I have to say I'm really impressed!

 My reference source is a Pioneer PD-91 and the Grub holds its own at a different level.

 I find the Grub's SQ is very transparent, detailed, airy, clean, and clear sounding. I'm noticing many more flaws in recording material. I'd say it's doing it's job very well so far.

 Any other impressions guys?


----------



## Juaquin

I know timelines are never exact and it's bad karma to name dates, but what's the general expectation on availability for kits? I'm guessing the key factor is the PCM's availability?


----------



## Billyk

Quote:


  Originally Posted by *ziplock* 
_Any other impressions guys?_

 

I agree with your assessment. This is a mighty widget, a giant killer if you will. Not quite as musical as some, but that is a totally subjective opinion, and that some are all a LOT more $$$.

  Quote:


  Originally Posted by *Juaquin * 
_I'm guessing the key factor is the PCM's availability?_

 

I know Mouser is expecting a shipment in June... I have 5 on order.


----------



## cobaltmute

There is PCMs coming before that.


----------



## ovrclkd

Can someone supply a finished picture of their production board with the components installed. I recently finished mine and connected it to the PC to make sure it powered up and was recognized before swapping the Bantam out of the MOSFET MAX. The board powered but windows 7 doesn't recognize it. I had doubts on the the orientation of the Wolfson (U3) and the Osillator (X1)

 Right about now TomB is shaking his head ...


----------



## cobaltmute

I'm mobile right now but you can look at the picture of tomb's one one the Beezar page to see the orientation. That is the same layout as the production board.


----------



## ovrclkd

Thanks cobalt ... mine appears to be correct except I've installed the mini USB (and my soldering's much neater! {just kidding, Tom's witnessed my "handywork"} 
	

	
	
		
		

		
		
	


	




)

 I've reflowed a few smd's after reading the posts here and checked for coldjoints & bridges but everything looks ok. LED is lit, nothing's warm or hot to the touch. I'll keep digging. maybe put another together in the meantime but if you have a list of checks I could use one.
 I will be building a total of three, one for the MAX, one with RCA's and another in a yet to be decided configuration.

 I noticed alot of "spare" thru holes, do I need to jump anything?
 Catch up with me at your earliest convenience.

 Thanks in advance,
 Jay R.


----------



## tomb

Sorry you're having troubles, Jay. There's a lot I still need to do to update the grubDAC website. I don't think this pic is actually up there right now. This is a closeup pic of one of the two I built - the PCB should be identical to the production PCB except the notches on the corners of the production PCB are slightly smaller and the production PCB is blue:




_[size=xx-small](click for a bigger pic)[/size]_


----------



## cobaltmute

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_I've reflowed a few smd's after reading the posts here and checked for coldjoints & bridges but everything looks ok. LED is lit, nothing's warm or hot to the touch. I'll keep digging. maybe put another together in the meantime but if you have a list of checks I could use one.
 I will be building a total of three, one for the MAX, one with RCA's and another in a yet to be decided configuration._

 

What voltage are you getting on the 3V3 point? This is the output of the voltage regulator. The LED is powered straight off the USB bus with no regulation.
  Quote:


 I noticed alot of "spare" thru holes, do I need to jump anything?
 Catch up with me at your earliest convenience. 
 

Define a lot. If you have a mini-USB build, you should have 4 holes next to the USB jack and the 3v3 test point. You may also have holes for C16 and C17 if you used the surface mount alternative. Other "holes" should be very small vias from the top to the bottom of the board.

 Pictures maybe?


----------



## ovrclkd

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_What voltage are you getting on the 3V3 point? This is the output of the voltage regulator. The LED is powered straight off the USB bus with no regulation._

 

No Voltage at 3V3 .... short somewhere?


  Quote:


 Define a lot. If you have a mini-USB build, you should have 4 holes next to the USB jack and the 3v3 test point. You may also have holes for C16 and C17 if you used the surface mount alternative. Other "holes" should be very small vias from the top to the bottom of the board.

 Pictures maybe? 
 

I was looking at the vias holes, must be a dozen or so... here's some pix, maybe something will jump out to the trained eye. 
	

	
	
		
		

		
		
	


	



 You'll see I chose to mount C9 vertically when I reflowed it due to lack of room.
 Thanks for your help! Please excuse my solder skills ... I'm still learning!


----------



## particleman14

hey all so i am building my grubdac.. however, when i plug it in i am geting usb device not recognized.
 my led lights up and i'm getting 3.3v at the test point.. 
 i could swear that there are no solder bridges on my chips.. but here are some pics of the board.. does anything seem amiss?? Photo Albums - Imgur


----------



## cobaltmute

ovrclkd, Your L3 looks a little weird. Can you check the resistance across it? It seems different than L1 and L2. You C9 and C14 also look a little different. I would suggest that you get used to using a lot less solder. There is a lot of blobs.

 particleman, The pics around both the PCM2707 and WM8524 aren't clear enough for me to pic up anything.

 I would advise that both of you go over your board with a good magnifying loupe. I personally use one of these. You'd be amazed at what you see under magnification.


----------



## tomb

EDIT: Never mind - I see cobaltmute posted.


----------



## particleman14

ok here are a few pics through my 40x loupe.. Photo Albums - Imgur
 i scrutinized each pin with my loupe after every smd.. and to me it seemed fine..but clearly something is wrong..


----------



## particleman14

after checking my 2 chips.. I am now about 95% convinced there are no solder bridges.. i even resoldered each pin again just to make sure... any suggestions I should try??


----------



## ziplock

Quote:


  Originally Posted by *particleman14* /img/forum/go_quote.gif 
_after checking my 2 chips.. I am now about 95% convinced there are no solder bridges.. i even resoldered each pin again just to make sure... any suggestions I should try??_

 

IMO double check all your passive SMD components. Several of them look questionable. Especially R2 R7 C14 and L2 (possible solder bridge across the top?). 

 While you're at it, see if you can get rid of any solder spikes by reflowing the solder joint(s) with a bit of flux. Solder spikes can introduce unwanted EMI/RFI into the circuit.

 If you still have problems, check the datasheet for both the TI and Wolfson ICs regarding maximum soldering duration and temperature for the pins. It's possible one of the ICs could have been damaged due to heat. I'll assume you followed safe ESD practices when handling the chips.

 Hope this helps.


----------



## Juaquin

If you want to be 98% sure of solder bridges, get a high powered (preferably LED) flashlight and shine it through the board from the back side. I'm not sure about the Grub but with the Bantam it made solder bridges very obvious.


----------



## particleman14

ya used the light to help look for bridges. still can't see any.. however, I refluxed and heated all my joints and still no dice. I am scared that perhaps i maybe fried my one of the chips.. will post up more pics after ive cleaned flux.


----------



## Juaquin

Yeah, it happens. Especially if this is your first SMD work. I fried a couple Bantams before I finally got one right. If only these DAC chips came in through-hole DIP packages - I'm sure there would be a lot less frustration in the world.


----------



## particleman14

well since the pcm2707s are out for a bit looks like this project is on hold for now..I don't mind though as the parts are cheap.. and i view these builds as more a learning experience with the added bonus of awesome functionality..


----------



## cobaltmute

Try the following to check on the chips as well, as looking straight down can miss bridges:

 Select an edge of pins you want to look at (say the WM8524)
 turn the board so that the pin are perpendicular to your board (running away from your body)
 Slowly drop the edge of the parallel side of the board, so you start looking down between the pins onto the body of the chip.

 I've had bridges that they only way you could see them was by doing this as they were behind the pins and not obvious.


----------



## particleman14

ya i've looked at it from this angle as well.. as far as I can tell there are no bridges..


----------



## tomb

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_No Voltage at 3V3 .... short somewhere?

 I was looking at the vias holes, must be a dozen or so... here's some pix, maybe something will jump out to the trained eye. 
	

	
	
		
		

		
			




 You'll see I chose to mount C9 vertically when I reflowed it due to lack of room.
 Thanks for your help! Please excuse my solder skills ... I'm still learning! 
	

	
	
		
		

		
		
	


	




 <IMG]http://i251.photobucket.com/albums/gg317/ovrclkd17/Audio/IMG_1782.jpg[/IMG>
 <IMG]http://i251.photobucket.com/albums/gg317/ovrclkd17/Audio/IMG_1781.jpg[/IMG>_

 

Your PCM and WM chips look OK - I can't see any bridges (where there's not a connecting via, anyway). I suspect the TPS chip on the back, though. In your back photo, the pin at the top left of the TPS chip looks a bit dodgy. That may also explain the lack of 3.3V at the test pad, too.

 Just a guess ...


----------



## particleman14

editt


----------



## ovrclkd

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_ovrclkd, Your L3 looks a little weird. Can you check the resistance across it? It seems different than L1 and L2. You C9 and C14 also look a little different._

 

I read zero ohms on L1,2&3 unplugged. Connected to PC is L1= 1.1 ohms, L2=1.1 & L3 is 0.2 

  Quote:


 I would suggest that you get used to using a lot less solder. There is a lot of blobs. 
 

You sir are too kind ... that is less solder ...lol (sorry)
 I have the same loupe and everything "appears" ok.
 The parts were bought off the BOM from digikey so they should be correct.

  Quote:


 Your PCM and WM chips look OK - I can't see any bridges (where there's not a connecting via, anyway). I suspect the TPS chip on the back, though. In your back photo, the pin at the top left of the TPS chip looks a bit dodgy. That may also explain the lack of 3.3V at the test pad, too.

 Just a guess ... 
 

Thanks for the suggestion Tom, I reflowed that leg but still no voltage at the 3v3. 

 Something for you both ... when I run a meter from the 5v to 3v3 it reads 5 volts, same if I test from 5v to D-, D+, & 0V

 C14 is 5ohms & C9 is 9 Mohms


----------



## ziplock

I wanted to bring up a parts issue with the current BOM of the GrubDAC. 

 If you opt for the standard *C5, C15 330uf 6.3V, 2.5mm ls,6.3mm dia max, 11.2mm high2Mouser647-UHE0J331MED* caps instead of the C5, C15 alts, the hammond case will not close properly. The 11.2mm height of these caps is too much. I had to drill two appropriately sized holes in order for the top to screw down flush.

 Just FYI...


----------



## tomb

Quote:


  Originally Posted by *ziplock* /img/forum/go_quote.gif 
_I wanted to bring up a parts issue with the current BOM of the GrubDAC. 

 If you opt for the standard *C5, C15 330uf 6.3V, 2.5mm ls,6.3mm dia max, 11.2mm high2Mouser647-UHE0J331MED* caps instead of the C5, C15 alts, the hammond case will not close properly. The 11.2mm height of these caps is too much. I had to drill two appropriately sized holes in order for the top to screw down flush.

 Just FYI..._

 

Yep - sorry that this tripped you up. I'll edit the BOM when I get a chance. In the future, the 560uf org-poly at DigiKey will be the primary choice we'll recommend. Those will be the ones included in the kits, too. The 220uf org-poly at Mouser and Beezar will also work, but you have to ensure that you solder them down as tightly to the board as possible. Those are the ones I used in my proto CableDAC builds, but I doubt there's enough room between the tops and the inside of the lid to slip a piece of paper in-between.


----------



## cobaltmute

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_C14 is 5ohms & C9 is 9 Mohms_

 

C14 show that there is an issue. There should be greater than 5Ohms between the positive rail and the negative rail.

 I'm guessing you used the Digikey BOM? Looking at your parts, and the BOM, I have discovered an issue. C9 and C14 in your build appear to 1206 parts. They should be 0805. The issue is with the BOM as during the development process we changed the size and changed the Mouser part, but not the Digikey one. 

 Somewhere on your board, there is a bridge from the positive rail to ground. Follow the traces from the 3v3 point and check all the pins that are attached to it for connectivity to ground. You'll have to do this by eye as all the pins are in parallel, so the reading should be the same.


----------



## ovrclkd

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_C14 show that there is an issue. There should be greater than 5Ohms between the positive rail and the negative rail.

 I'm guessing you used the Digikey BOM? Looking at your parts, and the BOM, I have discovered an issue. C9 and C14 in your build appear to 1206 parts. They should be 0805. The issue is with the BOM as during the development process we changed the size and changed the Mouser part, but not the Digikey one. 

 Somewhere on your board, there is a bridge from the positive rail to ground. Follow the traces from the 3v3 point and check all the pins that are attached to it for connectivity to ground. You'll have to do this by eye as all the pins are in parallel, so the reading should be the same._

 

NUTS ...... I JUST SOLDERED TWO MORE OF THOSE ON ANOTHER BOARD!

 The first board has had them off twice ... I'm having a hard time getting the solder to stick to the pads.
 I purchased 98% of these parts from the DK BOM (three kits worth) .... PLEASE review the rest of it.

 THIS EXPLAINS WHY THE SMD'S ARE WIDER THAN THE PADS!
 Back to de-soldering .......


----------



## tomb

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Yep - sorry that this tripped you up. I'll edit the BOM when I get a chance. In the future, the 560uf org-poly at DigiKey will be the primary choice we'll recommend. Those will be the ones included in the kits, too. The 220uf org-poly at Mouser and Beezar will also work, but you have to ensure that you solder them down as tightly to the board as possible. Those are the ones I used in my proto CableDAC builds, but I doubt there's enough room between the tops and the inside of the lid to slip a piece of paper in-between.
	

	
	
		
		

		
		
	


	


_

 

Maybe I accepted fault too quickly.
	

	
	
		
		

		
		
	


	




 Please note that 10.5mm is an accurate height clearance. However, quality electrolytics may have a rubber plug that causes them to exceed this height. The organic-polymer caps do not have as much of a plug and so the installed height is much less. That said, I have removed everything but the organic-polymers from the BOM. Standard electrolytics will work, but you are on your own with clearance using the Hammond 1551HTBU. We recommend the 560uf org-poly from Digikey as the primary choice (will also be available from Beezar and in the kits). It's only 10.5mm high.


----------



## tomb

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_NUTS ...... I JUST SOLDERED TWO MORE OF THOSE ON ANOTHER BOARD!

 The first board has had them off twice ... I'm having a hard time getting the solder to stick to the pads.
 I purchased 98% of these parts from the DK BOM (three kits worth) .... PLEASE review the rest of it.

 THIS EXPLAINS WHY THE SMD'S ARE WIDER THAN THE PADS!
 Back to de-soldering ......._

 

Sorry about that. It doesn't make you feel any better, I'm sure, but I had to mess with the same thing on both of the ones I built. I ordered C9 and C14 from Mouser when both were listed in the 1206 section of the BOM. I corrected it after that for the Mouser parts, but apparently missed it on the DigiKey column. This is really no excuse, but cobaltmute and I went through 6(!) revisions during design and prototyping. I was attempting to keep up each time with a revised BOM, but missed a couple of things along the way. The design has been "locked" for some time now, so there shouldn't be anymore changes. I guess some of you have still been acting as prototypers for the production version, in a way. Again, please accept my apologies.
	

	
	
		
		

		
		
	


	




 Please note that this has been corrected and some other major changes made to the BOM on the grubDAC website:
GrubDAC BOM

 These changes bring the BOM up-to-date with the latest pricing and more closely aligns the parts listing with the kit options that we'll be offering.
	

	
	
		
		

		
		
	


	




 NOTE: As always, if a BOM is linked to a specific part that is out-of-stock, please do a search on Mouser/DigiKey using the BOM description. Except for the IC's, there are many other parts available. Cobaltmute and I simply selected the parts with the lowest price and highest stock number at the time the BOM was first formulated. I make an attempt to update pricing from time to time, but some of these SMD passives can run out of stock in a day's time, depending on manufacturing product pressures in the industry.


----------



## ovrclkd

No worries ... always a learning process. 
	

	
	
		
		

		
		
	


	



 Thank you both for catching this and making the necessary changes.
 Everything happens for a reason ..... I'll order the correct parts and more solder 
	

	
	
		
		

		
		
	


	




 and hopefully have a grubDAC in working order for the MAX!

 Enjoy your Sunday guys .... I'm off for a spin!


----------



## ziplock

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Maybe I accepted fault too quickly.
	

	
	
		
		

		
		
	


	




 Please note that 11.2mm is an accurate height clearance. However, quality electrolytics may have a rubber plug that causes them to exceed this height._

 

That's one hell of a plug. The caps are almost flush with the top of the case after drilling.. lol

 Judging from the Nichicon DS, the length is measured top of cap, to plug, not just the cylinder housing alone.

 Anyway, at this point it's a non issue. I'm probably the only one who went with the ghetto caps.


----------



## tomb

Quote:


  Originally Posted by *ziplock* /img/forum/go_quote.gif 
_That's one hell of a plug. The caps are almost flush with the top of the case after drilling.. lol

 Judging from the Nichicon DS, the length is measured top of cap, to plug, not just the cylinder housing alone.

 Anyway, at this point it's a non issue. I'm probably the only one who went with the ghetto caps. 
	

	
	
		
		

		
		
	


	


_

 

 ... and I was wrong (again?) - the clearance height is 10.5mm, not 11.2mm. Again, please accept my apology - the BOM has been corrected with caps that will fit.


----------



## luvdunhill

please don't post in this thread Tom until you have the kits ready, ya tease! 
	

	
	
		
		

		
			





 just kidding 
	

	
	
		
		

		
		
	


	




 Assembling Tom's kit is like a day at the spa for me... none of these projects that drag out years and years, they come together in a few hours and just seem to work... no searching for parts at Mouser, only trying to find them on the floor occasionally


----------



## Juaquin

I'm waiting on 2 kits myself (one for my desktop, one for my upcoming all-in-one amp). Someone call China and tell them to hurry up on those PCM chips.


----------



## ziplock

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_... and I was wrong (again?) - the clearance height is 10.5mm, not 11.2mm. Again, please accept my apology - the BOM has been corrected with caps that will fit.
	

	
	
		
		

		
		
	


	


_

 

No worries Tom. 
	

	
	
		
		

		
		
	


	




 You fixed it and I'm probably one of few who used those caps.

 Anyway, rock on! Time to have a nice listening session with the mighty Grub.


----------



## sandbasser

A quick question about the BOM (the newest)... 

 Are the Mouser and DigiKey parts equal or should the DigiKey parts be preferred???

 Thanks,


----------



## cobaltmute

I would say that the only "preferred choice" from the Digikey BOM is the C1, C5, and C15 caps. These were chosen as nice large filtering/rail caps that fit the CableDAC case.

 Aside from that, the parts were chosen to be equal and available.


----------



## ovrclkd

Put a second one together and Win 7 recognized it straight away.
 I'll install it in the MOSFET MAX tomorrow. 
 I'd really like to piggy back the Bantam & Grub in there for some on the fly side by sides ....

 I checked the "non working" one and everything looks identical to the 2nd ...
 I've got something screwed up or fried but it's not visible.

 The third will be a cable version .... I'll post after I marry the Grub to the MAX


----------



## tomb

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_Put a second one together and Win 7 recognized it straight away.
 I'll install it in the MOSFET MAX tomorrow. 
 I'd really like to piggy back the Bantam & Grub in there for some on the fly side by sides ....

 I checked the "non working" one and everything looks identical to the 2nd ...
 I've got something screwed up or fried but it's not visible.

 The third will be a cable version .... I'll post after I marry the Grub to the MAX 
	

	
	
		
		

		
		
	


	


_

 

Congrats on getting the 2nd one to work! Good job!

 I don't know - you might be able to piggyback them with some tall standoffs for the board on top. Then simply run the 2nd one's leads to where you have the RCA inputs at the relay punch-down block. Then as you say, you could switch one from the other.

 However, you'd have to find something that would run in multiple instances on your PC so that you could avoid switching back and forth with sources in the software, too. I use Foobar and it won't let me run anything but one instance, so I have to switch the sources in the software, anyway.

 I've been switching the physical sources on mine already because I use the grubCableDAC version. I have that connected through the RCA jacks and then have an onboard Bantam. So, the physical switch makes the change easily enough. It's just a hassle to stop everything and switch it in the software, too. Maybe I'm not understanding something when it comes to the software, or perhaps there's another media player that will run in several instances while choosing different sources for each one? Actually, Foobar is more convenient than most, because it lets you select the source in the software. Many other media players force you to make the change through the operating system, which is a much bigger hassle.


----------



## GeWa

Any idea when kits will be available?
	

	
	
		
		

		
		
	


	




 Regards


----------



## tomb

Quote:


  Originally Posted by *GeWa* /img/forum/go_quote.gif 
_Any idea when kits will be available?
	

	
	
		
		

		
		
	


	




 Regards_

 

Well, I've been saying the last week of April to the first week of May. As it turns out, though, I'm going out of town during the first week of May - so maybe the 2nd week?


----------



## ovrclkd

Quote:


  Originally Posted by *tomb* /img/forum/go_quote.gif 
_Congrats on getting the 2nd one to work! Good job!

 I don't know - you might be able to piggyback them with some tall standoffs for the board on top. Then simply run the 2nd one's leads to where you have the RCA inputs at the relay punch-down block. Then as you say, you could switch one from the other.

 However, you'd have to find something that would run in multiple instances on your PC so that you could avoid switching back and forth with sources in the software, too. I use Foobar and it won't let me run anything but one instance, so I have to switch the sources in the software, anyway.

 I've been switching the physical sources on mine already because I use the grubCableDAC version. I have that connected through the RCA jacks and then have an onboard Bantam. So, the physical switch makes the change easily enough. It's just a hassle to stop everything and switch it in the software, too. Maybe I'm not understanding something when it comes to the software, or perhaps there's another media player that will run in several instances while choosing different sources for each one? Actually, Foobar is more convenient than most, because it lets you select the source in the software. Many other media players force you to make the change through the operating system, which is a much bigger hassle._

 

Just put the third Grub together which I'll finish with RCA jacks for output. No problems, Win 7 said hello as soon as I connected the USB cable (I drilled a 1/4" hole and used a 5mm led grommet in the hammond case for a chafe guard.)

 I decided to dig back into the first one and found a bad joint at U2. I resoldered it, Windows "saw" it but failed to recognize it. Both U2 and R4 are RED HOT and I have 1.4 volts at 3V3 now.. Your wisdom?

 Still haven't opened the MAX back up ... I was handed the honey do jar and it was a good day to get caught up and "bank" some time.


----------



## tomb

Quote:


  Originally Posted by *ovrclkd* /img/forum/go_quote.gif 
_<snip>
 I decided to dig back into the first one and found a bad joint at U2. I resoldered it, Windows "saw" it but failed to recognize it. Both U2 and R4 are RED HOT and I have 1.4 volts at 3V3 now.. Your wisdom?</snip>_

 

My wisdom says ask cobaltmute.
	

	
	
		
		

		
		
	


	




 Let's see what he says when he sees it.


----------



## cobaltmute

If R4 is getting hot, I suspect a problem with X1, C2 or C1. R4 is an 1/8W part. At 3.3V and 4ma (for the Digikey part), it should be passing 0.012W, which is well below what R4 should be handling.

 Possible bridge on X1,C2 or C1? or you've fried X1?


----------



## ovrclkd

Quote:


  Originally Posted by *cobaltmute* /img/forum/go_quote.gif 
_If R4 is getting hot, I suspect a problem with X1, C2 or C1. R4 is an 1/8W part. At 3.3V and 4ma (for the Digikey part), it should be passing 0.012W, which is well below what R4 should be handling.

 Possible bridge on X1,C2 or C1? or you've fried X1?_

 

Thanks for the quick reply.... YOU WERE CORRECT! 
	

	
	
		
		

		
		
	


	




 One of my "blobs" made its way to the casing around X1 causing a bridge.

 I am now the VERY proud owner of 3 working GrubDAC's, no easy feat for me .... 
	

	
	
		
		

		
		
	


	




 Now the best part, I connected the FIRST one to the MOSFET MAX and the difference in SQ between the Grub & Bantam is nite and day.
 The GrubDAC really brought the best out in the MAX. If I was asked to use one word to define the difference between a Bantam & GrubDAC it would be "Clarity". The Grub adds a new dimension and refinement to the music.
 Once again the reference file was Fleetwood Mac's "Rumours" album listening thru Grado 325i's. 

 Thanks again for the troubleshooting tips! 
	

	
	
		
		

		
		
	


	



 Time to update the MAX thread ... 
	

	
	
		
		

		
		
	


	






 ~Jay R.


----------



## mfaughn

Hi all,

 I built a grubdac many months ago and it never worked. I suspect that the dac chip is bad as I can detect no untoward voltages and no shorts. 

 I have all the parts on hand to try again (actually to build a bunch of them) but I have been waiting for months to get the DAC chips. Does anybody know of a source for these things? I am about to go with whatever random place gives me a reasonable quote from some of the chipfinder websites (if even that works). TI is supposed to be sending me samples but they keep revising their delivery estimate and it is now into August. I am hoping to get some before May 23.

 Thanks,
 Michael


----------



## cobaltmute

If you look at Mouser, they are scheduled for a large qty of both the PCM2706 and PCM2707 over the next few months.

 I would say patience is a virtue and to wait for these supplies. You never know what you might get or have to pay otherwise.


----------



## nightanole

I got the rev1 proto version.  My active volume control says it needs a source impedance of 600ohms or lower and control has a input impedance of 12k.  The WM8524 dac says it "likes" input inpedances between 1k -49k.  So am i safe?
   
  If im not safe can some one recommend a simple buffer that can run off of my onboard supply of +-15vdc regulated? Maybe the LMH6321 or a simpler single chip one?  I could even go 2x gain if its a simpler higher end one.


----------



## cobaltmute

What volume chip are you using? The WM8524 is happy driving 10k pots with no issue so I'm guessing you are fine. I've driven a PGA2311 without issue from a grubDAC


----------



## nightanole

http://focus.ti.com/lit/ds/symlink/pga2320.pdf
   
  page 7


----------



## tomb

As best I can tell, all the parts are here for kits.
	

	
	
		
		

		
			




   
  However, please give me a few days to a week to get them prepared.  I hoped I would've had them done by now - but early this week, my primary hard drive died.  I've been out of pocket re-building/installing everything since.
	

	
	
		
		

		
		
	


	







  I still have a few odds and ends to restore, but it's getting close.


----------



## cobaltmute

Quote: 





tomb said:


> However, please give me a few days to a week to get them prepared.  I hoped I would've had them done by now - but early this week, my primary hard drive died.  I've been out of pocket re-building/installing everything since.
> 
> 
> 
> ...


 
   
  Hard drive crashes suck big time.
   
  I use a Symantec product to image my whole drive about every month and the backup drive sits off most of them time.  You may want to look at this:
   
http://www.acronis.com/homecomputing/products/trueimage/

  Image your drive to a backup and then pull it back at will if required. I haven't used TrueImage for a while, but it worked when I did run it.


----------



## Juaquin

Quote: 





tomb said:


> As best I can tell, all the parts are here for kits.


 

 Excellent news! Can't wait.


----------



## tomb

Quote: 





cobaltmute said:


> Hard drive crashes suck big time.
> 
> I use a Symantec product to image my whole drive about every month and the backup drive sits off most of them time.  You may want to look at this:
> 
> ...


 

 Yep - I think everything's back together now.  I actually went the cheap route and ghosted another drive with Seagate's Disk Wizard.  Running Windows 7, I was able to bcdedit the bootloader to run either drive at startup.  Anyway, once I chop down all the weeds that overgrew the yard while this was going on, I should be able to get the kits together.


----------



## Zigis

Sorry, wrong post.


----------



## GeWa

Any update on these little buggers, kits I mean?
   
  Regards


----------



## tomb

Quote: 





gewa said:


> Any update on these little buggers, kits I mean?
> 
> Regards


 

 I'm working on them as I type this - maybe just a few more days.


----------



## Yaka

put me down for 3 then tomb


----------



## GeWa

That's good news. I'll take one to start with.
   
  Regards


----------



## viralbug

Great, I'm looking forward to my first DIY.

 One question tomb, will there be a limited stock of the kits? If so, I'd make sure to order a kit for myself so that I won't have to wait for another stock.


----------



## tomb

Quote: 





viralbug said:


> Great, I'm looking forward to my first DIY.
> 
> One question tomb, will there be a limited stock of the kits? If so, I'd make sure to order a kit for myself so that I won't have to wait for another stock.


 

 The way the PCM chips are in availability, sales over the long-term will most likely occur in spurts with out-of-stock periods in-between.  I hope that's not the case, though - my intent is certainly to keep them in stock at all times.  It's not like the Starving Student where there was a limited number of tubes in existence in the whole world.  The chips that cobaltmute selected for the design are in active production and there's no indication of that stopping.  Nevertheless, production fluctuates wildly for the PCM chips from TI.  I don't know what it is about TI's Burr-Brown chips, but I remember that we went through the same thing with BUF634's several years ago when a couple of popular DIY headphone designs used them (PIMETA, Millett Hybrid).  There would be several hundred available at Mouser and DigiKey for awhile, then they'd sell out of stock and it was 6 mos to a year before they'd even appear again.
   
  I'll try to keep the stock as best I can, but it's kind of expensive to order 250 up front every time I turn around.  We'll have enough for 100 kits to start, with it being pretty easy to do another 100 after that.  At that point we may need new PCB's too, so we'll have to see how easy it is to re-load for another couple of hundred or so.  Also, we'll need to see whether something else has come down the pike that may be better (I doubt it unless it's from cobaltmute himself.
	

	
	
		
		

		
		
	


	




).
   
  I'm working on a Build Thread right now and should have the kits ready a few days later, so I'm maybe a week behind.  Please be patient with me.  This little DAC is worth the wait awhile longer.
	

	
	
		
		

		
		
	


	



   
  Here's a pic of what I mean - PCM chips in high bulk
	

	
	
		
		

		
		
	


	




:


----------



## tomb

Here are a couple of teasers:
   
  Checking for bridges using a simple 60W bulb -
   





  I'm actually using this one to put in a MOSFET-MAX, but I will wire the LED to the front panel. I wanted all the parts in the pic, so the LED is in the holes, but not soldered.


----------



## sachu

That is sweet Tomb..
   
  Are the boards shipping for this already. I have a really cool amp build coming up and would love to have this built in.
  In fact i just placed an order for the board..hoping I can have it by the weekend so I can finish the build..
	

	
	
		
		

		
			




  Seems mouser was out of the LDO regulator specced in the BOm..so went for this one
   
  They had the Wolson DAC too which is cool. I had a PMC2706/7 to use for the USB to I2S. A nice little DAC on the cheap..awesome!


----------



## tomb

Quote: 





sachu said:


> That is sweet Tomb..
> 
> Are the boards shipping for this already. I have a really cool amp build coming up and would love to have this built in.
> In fact i just placed an order for the board..hoping I can have it by the weekend so I can finish the build..
> ...


 
  Yes, the PCB's have been shipping for awhile, now.
   
  As for the LDO regulator, as long as it's "TPS79333" it should be OK.  It's impossible to keep up with the suffix designations on some TI chips.  They change them with almost every manufacturing cycle.  When in doubt, type the BOM's description into the Mouser search field instead of using the BOM's direct link.  Most of the time, you'll get plenty of acceptable alternates or "as-equals."


----------



## cobaltmute

The TPS79333 comes in:
   

 RoHS
 non RoHS
 Automotive
 Military Enhanced
   
  versions.
   
  Any version will work fine.  The major difference is that some versions are run through an enhanced quality control process.


----------



## barsk

Kits available soon?
  I am eager!


----------



## sachu

jeez..these ICs are near impossible to solder with the tip i have..


----------



## tomb

Quote: 





sachu said:


> jeez..these ICs are near impossible to solder with the tip i have..


 


 Sorry if you're having trouble, but actually - they're easier to solder than the PCM2702 on the Alien and Bantam, for instance.  I use a 0.8mm chisel tip on my Hakko (1.6mm is the standard Hakko tip).  Solder is 0.025", 63/37 Kester 44, but I use that for everything.
   
  Be sure you read the soldering tips on the GrubDAC website - http://www.diyforums.org/GrubDAC/GrubDACsolder.php, and the link to Tangent's tutorial video on SMD soldering that's on that page.  Also, until I get the step-by-step of the GrubDAC done, refer to the BantamDAC step-by-step instructions.  There are a lot of good tips in there.


----------



## sachu

well i got it done and hooked it up to my computer. Device was recognized, foobar plays fine with it..but i have output going to my amp


----------



## GeWa

Well, isn't it that what it is supposed to do?
   
  Regards


----------



## sachu

i meant..i have no sound output from the DAC.


----------



## cobaltmute

Check for bridges on the WM8524.


----------



## Juaquin

Quote: 





tomb said:


> Sorry if you're having trouble, but actually - they're easier to solder than the PCM2702 on the Alien and Bantam, for instance.  I use a 0.8mm chisel tip on my Hakko (1.6mm is the standard Hakko tip).  Solder is 0.025", 63/37 Kester 44, but I use that for everything.


 

 I used the exact same materials (well, my Hakko is a clone, but same tip, solder) and I agree that the Grub's IC is a lot easier to solder down than the Bantam, even considering that it has four sides. I've fried two Bantam's but my first Grub came out perfect. Regardless, SMD is a pain in the butt. Wish the manufacturers would make a DAC in a DIP package.


----------



## cobaltmute

I use a 1.6mm tip with 0.031" solder. Takes some patience and a very gnetlr hand not to get too much solder. 



 They do sell DIP DACs but you still end up having to deal with something that is SMD along the chain.


----------



## GeWa

The key ingredient here is solder flux. Flux the pads and pins thoroughly and tip each pin with a good tinned solder-tip. A 1,6mm solder-tip works even better than a 0,8mm because there is much more heat in the tip.
  At the age of 48 and an eyesight that is not what it used to be I manage quite well to solder these little buggers with good result.
   
  Regards


----------



## Ikarios

Is it just me, or are PCM2706/2707s out of stock until mid-Augustish? I've checked TI, Mouser, and Newark (my three potential sources) and all three are out of chips. Is the Grub that popular?
   
  Also, is there a difference between the PCM2706 and the PCM2707? I checked the datasheets but it seems like the two use the same pdf, just titled differently, so I'm inclined to believe the difference is negligible for our uses.


----------



## cobaltmute

The difference between the PCM2706 and the 2707 is that the 2706 supports an external rom for supplying descriptors to the host (PC).  For the purposes of the grub, they are inter-changable.
   
  The PCM chips are ones that unfortunately go in and out of stock.  Several projects, like the grub and the gamma1 can be affected by this.  I know that tomb/Beezar has stock  but I believe with CanJam coming up he is tied up with other items and this is keeping him from putting the kits up in his store.


----------



## Juaquin

Yes, everyone's out of stock. It's not the Grub (at least, not all of the demand). Dozens of other things use that part. Luckily TomB was able to order a bunch of them for the kits. Not sure about the difference between the two but I doubt they're interchangeable (or else people would have done it).


----------



## cobaltmute

Quote: 





juaquin said:


> Not sure about the difference between the two but I doubt they're interchangeable (or else people would have done it).


 

 We've already done it. 
	

	
	
		
		

		
			





  If you check the grubDAC build thread that tomb has posted, you'll notice that he has used the PCM2706 for his builds.  You can used a PCM2706 for a PCM2707, but the reverse may not be true


----------



## sachu

wait a min..so the PCM2707 doesn't wok in the grubDAC?


----------



## tomb

Quote: 





sachu said:


> wait a min..so the PCM2707 doesn't wok in the grubDAC?


 

*The PCM2706 and PCM2707 are completely interchangeable on the grubDAC.*
   
  Also, from cobaltmute a couple of posts back:
   
  Quote: 





> The difference between the PCM2706 and the 2707 is that the 2706 supports an external rom for supplying descriptors to the host (PC).  *For the purposes of the grub, they are inter-changable.*


----------



## sachu

heh..really need to stop going to bed so late..oh well..guess means more debugging the board then. So far, best as i can tell there are no bridges on the wolfson part. Will go over it again however.


----------



## tomb

Quote: 





sachu said:


> heh..really need to stop going to bed so late..oh well..guess means more debugging the board then. So far, best as i can tell there are no bridges on the wolfson part. Will go over it again however.


 

 Can you post a pic?  The light bulb trick in the build thread works for me, but photographing the PCB with a decent macro lens setting is a pretty good method, too.  You can blow it up to see a lot more details.  Plus, there's always the chance that someone may be able to spot something that you may have missed.


----------



## cobaltmute

Sachu,
   
  Since you DAC was recognized, IIRC, the issue is between the PCM2707 and the WM8524 or the WM8524 itself.  You'd need to check for bridges on the output pins of the PCM2707 and the input pins of the WM8524.  The input pin on the WM8524 are the 4 pins (2 on each side) closest to the PCM2707.  You could ohm them out to see if there are any bridges.


----------



## Juaquin

Quote: 





cobaltmute said:


> We've already done it.
> 
> 
> 
> ...


 

  Apparently I need to work on my reading comprehension. Sorry for the confusion!


----------



## GeWa

Stirring things up a bit, any idea when there will be any kits available?
   
  Regards


----------



## pabbi1

Tom was gracious enough to allow my brother to purchase a completed GrubDAC at CanJam, which I dropped into his SOHA II. Simply a great pairing for a guy with a laptop living in the sandbox.
   
  From what I have heard so far, great job, and synergizes very well with his Grados.


----------



## tomb

Quote: 





pabbi1 said:


> Tom was gracious enough to allow my brother to purchase a completed GrubDAC at CanJam, which I dropped into his SOHA II. Simply a great pairing for a guy with a laptop living in the sandbox.
> 
> From what I have heard so far, great job, and synergizes very well with his Grados.


 
  Thanks for the comments!  Glad to hear it worked!  I had not had a chance to test it out.  Your brother purchased one of the two I built in the GrubDAC Build Thread.
   
  Now, if I can just get those kits going.  I'm about 75% there, but other things keep interrupting.  Hopefully, it'll be very soon.


----------



## the_equalizer

Quote: 





tomb said:


> Thanks for the comments!  Glad to hear it worked!  I had not had a chance to test it out.  Your brother purchased one of the two I built in the GrubDAC Build Thread.
> 
> Now, if I can just get those kits going.  I'm about 75% there, but other things keep interrupting.  Hopefully, it'll be very soon.


 

 I'm very interested in one or two of those kits. Will you annonunce when they're availabe in this thread?
   
  cheers !


----------



## tomb

Quote: 





the_equalizer said:


> I'm very interested in one or two of those kits. Will you annonunce when they're availabe in this thread?
> 
> cheers !


 
  Most likely I'll ask cobaltmute to do that.
	

	
	
		
		

		
		
	


	




  It might violate the rules since I'm a MOT.
   
  It should be next weekend, but I've said that before.
	

	
	
		
		

		
		
	


	




  Unfortunately, I ran into some issues building the kits for the RCA output leads - seems I had to re-calculate the heat shrink pieces a number of times and re-order stuff.  Also, packaging up between two and three thousand SMD parts has been a bit of a grind.


----------



## Juaquin

Quote: 





tomb said:


> Also, packaging up between two and three thousand SMD parts has been a bit of a grind


 

 I do NOT envy you. Wow.


----------



## the_equalizer

Quote: 





juaquin said:


> I do NOT envy you. Wow.


 

  
  Indeed.  Another admirable effort, for sure.


----------



## cobaltmute

Approximately 42 parts x 100 kits = ~4200 parts.
   
  And I say approximately as IIRC there will be the base kit (for the board and parts) and then the cable kit (which will add everything required including case, plugs etc to make a cable DAC).
   
  I'm just glad it isn't me....


----------



## Yaka

wots a mot?


----------



## pistolsnipe

M.O.T. = Member Of the Trade


----------



## tomb

Quote: 





cobaltmute said:


> Approximately 42 parts x 100 kits = ~4200 parts.
> 
> And I say approximately as IIRC there will be the base kit (for the board and parts) and then the cable kit (which will add everything required including case, plugs etc to make a cable DAC).
> 
> I'm just glad it isn't me....


 

 Well, I'm glad you're you and that you designed such an excellent little DAC.  It will be worth it all to bring it to the community.  I'm just asking for a bit more patience from everyone.  You're right about the estimate, too - I was just counting the SMD parts.
	

	
	
		
		

		
			




   
  All I lack is packaging up the IC parts, taking some pics to make the listing on Beezar (one afternoon), and away we go.  The problem is that there are other things going on at the same time and it's all I can do to manage that stuff during the work week.
	

	
	
		
		

		
		
	


	




  Anyway, I think enough people want these that I wanted to make sure that I had at least 100 of them ready to go in an instant so that I didn't get behind/overwhelmed ... and we're close.


----------



## arteom

Hopefully the pcb and usb wire from tomb will arrive tomorrow so I can start assembling. Was quite surprised when I actually saw the size of the case, this thing is tiny! Quick question, what is the recommended diameter of holes on either side of the case? Also is the top cover to act as a sort of a holster for the cables so they don't move around and detach?


----------



## Ikarios

I had a thought - since the GrubDAC draws power over USB, if it's plugged in it's on, right? Is there any way to add a power switch to the thing in its current PCB form? Reason I'm asking is I want a relatively easy way of turning the Grub off whenever I won't be using my SSMH (read: using speakers), but I don't want to mess with the interconnects due to the issue the SSMH has with wantonly killing innocent DACs.


----------



## Juaquin

Just install a switch in the 5V line between the USB plug and the Grub.


----------



## cobaltmute

Replacing L1 with a switch is one option.   Other option is to wire the enable pin of the TPS reg to a switch which will shut down the regulator and therefore the rest of the board.
   
  With the L1 case, the LED would be switched.  If you switched the regulator the LED would always be on.
   
  A third option would be to not populate the grub power section, take the 5V feed from near marked point and power the 3v3 point with your regulated switched 3.3V using your own regulator.


----------



## particleman14

heres a pic of my new grub cable dac.  i really like the look and the form factor.  I plan on building more! great design and the case is perfect.


----------



## MASantos

Looks great!! I'll probably be building a few of these for friends! For the price it's a no brainer!


----------



## Ikarios

Quote: 





cobaltmute said:


> Replacing L1 with a switch is one option.   Other option is to wire the enable pin of the TPS reg to a switch which will shut down the regulator and therefore the rest of the board.
> 
> With the L1 case, the LED would be switched.  If you switched the regulator the LED would always be on.
> 
> A third option would be to not populate the grub power section, take the 5V feed from near marked point and power the 3v3 point with your regulated switched 3.3V using your own regulator.


 

 Hmm... so I can install an SPST switch completely in place of the L1 ferrite? Just solder a couple wires, no original ferrite, and that will be just fine? That seems a lot easier than moving the USB plug off-board and connecting five wires to the board. I like the idea of having the LED show the power status of the DAC so that sounds like the best way to go.


----------



## cobaltmute

Quote: 





ikarios said:


> Hmm... so I can install an SPST switch completely in place of the L1 ferrite? Just solder a couple wires, no original ferrite, and that will be just fine? That seems a lot easier than moving the USB plug off-board and connecting five wires to the board. I like the idea of having the LED show the power status of the DAC so that sounds like the best way to go.


 
   
  Yup, that would be correct.
   
  You can also put a ferrite in-line as close to the board as possible.  An example would be this:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P9820BK-ND
  
  If you put it close to the pad on the LED site of L1, you would wouldn't lose much at all.


----------



## cobaltmute

Quote: 





particleman14 said:


> heres a pic of my new grub cable dac.  i really like the look and the form factor.  I plan on building more! great design and the case is perfect.


 

 If you PM me, I'll throw some screws in an envelope to mount that board to the case...


----------



## cobaltmute

It appears that there is a new category page at Beezar 
	

	
	
		
		

		
		
	


	



   
http://beezar.com/oscommerce2/catalog/index.php?cPath=40
   
  Great work tomb.


----------



## arteom

So I completed one of these, got the parts mouser and used a mogami star quad wires. Here is the odd thing, the blue led comes on, the test point reads 3.3v, and at times my computer recognizes and installs drivers... But at other times I get a device not recognized error. I would not get this error at all before I installed the mogami wire, so I tried again, this time around I got it to work, got sound, listened for a 10 or 15 minutes, at around that time the sound started to get coarse, I touched the cable and the sound cut off, tried to take usb plug out and plug back in and yet again I get... USB device not recognized. Am I just doing a poor job installing the output cables?


----------



## Juaquin

Quote: 





cobaltmute said:


> It appears that there is a new category page at Beezar
> 
> 
> 
> ...


 

 Ordered! Thanks again Tom!


----------



## tomb

Quote: 





arteom said:


> So I completed one of these, got the parts mouser and used a mogami star quad wires. Here is the odd thing, the blue led comes on, the test point reads 3.3v, and at times my computer recognizes and installs drivers... But at other times I get a device not recognized error. I would not get this error at all before I installed the mogami wire, so I tried again, this time around I got it to work, got sound, listened for a 10 or 15 minutes, at around that time the sound started to get coarse, I touched the cable and the sound cut off, tried to take usb plug out and plug back in and yet again I get... USB device not recognized. Am I just doing a poor job installing the output cables?


 

 Let's wait for cobaltmute to help you, but my guess is yes - there's something wrong in how you've connected the output cables.  You can get a horrible noise if the ground wires are not making good contact, or you can lose the sound altogether.  I'm not sure if this would have anything to do with your computer not recognizing the DAC, but if the output wires are shorted, it might.
   
  As I said, let's see what cobaltmute says ...


----------



## cobaltmute

I'm sitting in a plane by I'd reflow every joint. Sounds like it might be a cold solder joint that might be flexing with movement


----------



## Ikarios

Has anyone tried putting a GrubDAC (non-cable) in a larger metal enclosure, like the Hammond 1455C1201BK (the longer version of the enclosure specced for the AlienDAC)? I'd prefer to have my DAC to have a little more substance on my desk, plus it'll match the SSMH case. Anything I need to be aware of if I do it this way?


----------



## ShinyFalcon

Sure you can. It'll be easier to work with too, since there's more space. If you get the metal panels, it's not as easy to work with as plastic. Just make sure that you line the hole up with the mini USB jack. I don't know if you can put your RCA jacks/cables in the same side as the USB jack, so it may have to be front panel mounted, essentially making it a cable DAC.
   
  Edit: Took a look at the case. If you mount it using the slots on the side, it may be a very tight fit. FYI.


----------



## Fishline

I just checked on mouser, and it looks like PCM2707PJT is back in stock.  However, the low dropout regulator (TPS79333DBVRQ1) is still out of stock (even though the estimated ship date is July 1st).  Is there an alternative that's in stock at mouser?  Also, the crystal oscillator (C3392-12.000) is non-stocked with minimum order of 550.  Is there a suitable replacement for at at mouser as well?
   
  (I've already bought the production PCBs a few months ago, planning to use them with the Carrie amp, so the Beezar kit doesn't help me...)


----------



## ShinyFalcon

LP2985A-33DBVR for the 3.3V regulator
  549-C3391-12.000 for the crystal


----------



## amc

Quote: 





shinyfalcon said:


> Sure you can. It'll be easier to work with too, since there's more space. If you get the metal panels, it's not as easy to work with as plastic. Just make sure that you line the hole up with the mini USB jack. I don't know if you can put your RCA jacks/cables in the same side as the USB jack, so it may have to be front panel mounted, essentially making it a cable DAC.
> 
> Edit: Took a look at the case. If you mount it using the slots on the side, it may be a very tight fit. FYI.


 
   
  If it is non-cable - you will be putting RCA's or a mini TRS jack panel mounted on the case, and the USB connector could be touching as well.  using metal panels, would there be any grounding issues?  Should the jacks be isolated?


----------



## Ikarios

Quote: 





amc said:


> If it is non-cable - you will be putting RCA's or a mini TRS jack panel mounted on the case, and the USB connector could be touching as well.  using metal panels, would there be any grounding issues?  Should the jacks be isolated?


 

 This is what I was concerned with as well, but I just discovered Mouser's PDF catalog of Hammond cases, and it seems plastic end panels are cheaper than the equivalent metal end panel enclosure, so I don't see any reason why metal would be any better (besides aesthetics, but this is supposed to be an inexpensive DAC anyway...). I think in this case it would be easier to find a USB jack that's panel-mount and wire it to the PCB instead, then secure the PCB to the case using hot glue or something. I'll peruse the Hammond offerings, compare them to TomB's SSMH Hammond case, and see which one would work the best. The 1455J1202BK seems like a good compromise between physical presence and panel space.


----------



## Fishline

Quote: 





shinyfalcon said:


> LP2985A-33DBVR for the 3.3V regulator
> 549-C3391-12.000 for the crystal


 

 Got it.  Thanks so much!
   
  Unfortunately looks like some of the xicon caps for the Carrie are not out-of-stock at mouser...  Why can't they stock these things all at once?  Will ask in the Carrie thread for appropriate replacement for those.


----------



## amc

Thanks for putting the kits togther tomb, my order has been placed.


----------



## the_equalizer

One more kit ordered!    Thanks to all those involved in making these kits possible.
   
  cheers!


----------



## Aalelan

As others have said, thanks to all that are/were involved on this one! and thanks to Tomb for putting the kits together, I got mine and it rocks!


----------



## VncentValntine

I've looked and looked through this thread but I am unable to find a for-sure value for what current the grub supplies the carrie with,  I appreciate the help =)


----------



## Juaquin

The Grub doesn't technically supply the Carrie. The Grub voltage input is directly from USB, and the Carrie piggybacks on that USB power source. So it's a question of what current the computer supplies both the Grub and Carrie over the USB cable (max for most computers is 500ma, which is sometimes a problem). The Grub has no effect on the supply of the Carrie (except for the supply running through traces on the Grub and the bit of capacitance across the rails).


----------



## VncentValntine

Ahhh I see...   That helps a lot, thanks!


----------



## cobaltmute

Juaquin is correct.  The 5V point on the grub is directly connected to the USB bus.  So your maximum current you can draw from here is ~450 ma (500ma for USB standard - ~50ma that the grubDAC draws for itself).


----------



## nate911

Just ordered a cableDAC kit--thanks tomb!


----------



## GeWa

I received mine today 
	

	
	
		
		

		
			




   
  Regards


----------



## tomb

I have an embarassing announcement about the kits.  It seems that we made a mistake on the BOM (we only went through 6 iterations of the design!).  C5 is listed as one of the 805 capacitors *and* as one of the three electrolytics.  C5 is one of the three electrolytics, though - *there is no SMD C5*.
   
  I'll be correcting the BOM shortly, but with close to 100 kits already packed, I'm not going to worry about having a single 805 capacitor as an extra.  Just don't scratch your head too long when you see a "C5" included in the 805 capacitor pack. 
	

	
	
		
		

		
		
	


	



   
  Thanks - let us see some pics of your progress when you can!


----------



## cobaltmute

I have to take as much responsibility as tomb for the kit mess up.  As tomb has stated, we did revise the BOM several times, I *tried* to audit it and did build from the BOM several times. 
	

	
	
		
		

		
		
	


	



   
  At least it is one extra part as opposed to short a part.  And it gives you an extra for when you flip one into the carpet...


----------



## limpidglitch

I just started on putting together a GrubKit, and I feel like pointing out the obvious: This smd stuff is freaking tiny!
  I need to keep both hands on the iron to minimize my trembling, and those several cups of coffee I just had was probably not a very good idea either.
  I want to thank the good people who put this whole thing together, including the brilliant step-by-step guide, for making it a very un-intimidating project for a first time DIYer.
   
  Here's my current progress. Think I will have the board fully populated by the end of the week-end, don't want to stress this.
   

   
  And another thing: Water soluble flux is pretty neat.


----------



## Billyk

Congrats, it looks great.
  Yep Coffee is not your friend with this type of work. You may come to prefer it though. I know I like it more that through hole now. If I could only see it better, but these old eyes just aren't what the used to be!


----------



## limpidglitch

Thanks.
  I've never actually tried through hole soldering, but I see few are included in the kit, so I'll soon find out what I prefer


----------



## Aalelan

So, could one add a TOSlink input to this?  even if it were a seperate little board that ribbon cable attached to the GRUB..  I really come up with crazy ones when I sit for too long 
   
  AA


----------



## cobaltmute

I think you would have better luck trying to put a wm8524 into a gamma1. There is not the right chips on the grub to support toslink.


----------



## limpidglitch

It's alive!
   
  I've actually made a thing that _works_ 
   
  Now to make an enclosure.


----------



## Aalelan

Quote: 





limpidglitch said:


> It's alive!
> 
> I've actually made a thing that _works_
> 
> Now to make an enclosure.


 
   
   
  Congrats!!  that solder work looks great!  If thats how you solder with coffee in you system maybe I should try it   
   
  AA


----------



## cobaltmute

Yup.  Good work and nice and clean soldering.


----------



## tomb

Quote: 





cobaltmute said:


> Yup.  Good work and nice and clean soldering.


 

 Ditto - some nice photography, too.


----------



## limpidglitch

Thank you for the kind words.
   
  About the coffee: I wizened up and exchanged the coffee for a cup of yorkshire tea with milk.


----------



## the_equalizer

Well, I got my package yesterday, outstandingly well packed as usual from Beezar, and set out to assemble the kit today. Somewhat surprisingly I had a really tough time with the tiniest SMD parts, even though just some 3 months ago I assembled a Bantam DAC without any problem at all.
   
  Anyway, after 6 hours of struggling, cursing and swearing I finally got the device assembled... and I thought my Bantam DAC was small !    And the sound! Clear and fluid as water from a mountain spring!
   
  Here it is next to its 'heavier weight' companion

   
  Thanks again to all those involved with the design, testing, documentation and making kits for this cool little DAC available, you all did a *great* job!
   
  cheers!


----------



## cobaltmute

Quote: 





the_equalizer said:


> Well, I got my package yesterday, outstandingly well packed as usual from Beezar, and set out to assemble the kit today. Somewhat surprisingly I had a really tough time with the tiniest SMD parts, even though just some 3 months ago I assembled a Bantam DAC without any problem at all.


 
   
  None of the parts on the grubDAC are any smaller than the Bantam.  It was designed that way on purpose 
	

	
	
		
		

		
			





  But yeah, even I say they are small every time I build one.
   


> And the sound! Clear and fluid as water from a mountain spring!


 
   
  That is an eloquent way of describing the sound.


----------



## kugino

been away from the forums for awhile...been looking for a new little project and me likes the look of this.  think i'll pick up a few kits...thanks for putting this together, guys!


----------



## m0b1liz3

Quote: 





> Clear and fluid as water from a mountain spring!


 
   
  Does this mean you prefer it over the Bantam DAC??
   
   
   
  Are all these kits coloured like that?  I am not partial to white cable.  If I built it, I would go black. 
   
  Can you use this in reverse???  (ie.  take an analog signal and convert to digital for recording?)
   
  I had an idea of building a tube preamp for guitar and then have it output to the GrubDAC rcas into the computer for digital recording.


----------



## cobaltmute

I believe that all the kits use the same white cable.
   
  You can Techflex the USB cable.  I've done it on one build that I did.
   
  As for the grub being used as an ADC - no.  Completely wrong chipset for that use.


----------



## the_equalizer

Quote: 





cobaltmute said:


> None of the parts on the grubDAC are any smaller than the Bantam.  It was designed that way on purpose
> 
> 
> 
> ...


 

 Thanks, that's just what came to my mind last night as I sat listening to a classical guitar duet in Magnatune through the GrubDAC.  Thanks for making this sweet little piece of equipment available to the community.
  
  Quote: 





m0b1liz3 said:


> Does this mean you prefer it over the Bantam DAC??
> 
> 
> 
> ...


 

 No, not at all, it's just what came to my mind while listening to the GrubDAC for the first time. The BantamDAC sounds wonderful too. I just wanted a DAC with no caps in the signal path to go together with the Dynalo I'm (slowly) building.
   
  About the white cable, besides cobaltmute's suggestion of using black techflex, you can also order the regular kit (not the 'cable DAC' one) and use a black USB cable.
   
  cheers!


----------



## MrDavis

This is only my second DIY project and by far the smallest parts I've had to solder.  I think I managed to get it right though...


----------



## MrDavis

This is only my second DIY project.  These are some small parts to solder but I think I got the first one right...


----------



## Aalelan

Quote: 





mrdavis said:


> This is only my second DIY project.  These are some small parts to solder but I think I got the first one right...


 

 For just your second DIY and what might have been your first SMD experince, looks good..  The more you do the better you will get too..   I read somewhere that the little solder tips/points should be avoided but I'm not sure if there is any noticable side affects because of them, maybe someone else can chime in on that one..
   
  I think if you use a little less solder, a little more flux and just a tad more heat you can prevent those..
   
  AA


----------



## cobaltmute

Good clean soldering with not too much solder. Nice Job.
   
  It may be just the picture, but I'd double check the two spots I highlighted.  Could be a bridge on both.


----------



## Ikarios

How would I go about building a GrubDAC directly into the casing of a Starving Student Millet Hybrid, but still have the option for RCA input? Would I solder the output and ground wires on the Grub to the signal and ground pins (respectively) on the RCA jack, then solder wires from the RCA as usual? Since I plan on using a power switch for the Grub portion, I can still turn off the Grub portion and connect RCAs from another DAC and not have any issues, right?
   
  The problem with this configuration is finding a way to mount the mini-USB connector... are there panel mount USB jacks? Has anyone tried this kind of method?
   
  The reason I like this method is it will save me at least $15 bucks, and save on desk space and clutter. I don't want to use the dinky plastic hammond enclosure, but the most suitable metal enclosure I can find is $15, and it saves the cost of buying RCA ICs. If only hammond made slightly-bigger-than-altoids tin-sized aluminum chassis for cheap...


----------



## cobaltmute

As I saw this before your edit, that case looks to be the black version of one of these:
http://www.hammondmfg.com/dwg.htm
   
  As for switching, a DPDT switch would seem the answer.


----------



## the_equalizer

As cool as the Starving Student Millett + GrubDAC combo is (I've been using it for a couple of days at the office), I'd be very careful with casing them together; the SSMH is known to blow DAC's if these are connected/disconnected while the amp is on, essentially what the switch does. Search the SSMH thread for more info.
   
  I can't comment much on your original idea of doing away with the switch and connecting the analog RCA inputs in parallel with the DAC's output, except that I seem to remember reading somewhere that it's also a dangerous idea... maybe because of the possible ground conflicts?
   
  cheers!


----------



## Ikarios

Quote: 





the_equalizer said:


> As cool as the Starving Student Millett + GrubDAC combo is (I've been using it for a couple of days at the office), I'd be very careful with casing them together; the SSMH is known to blow DAC's if these are connected/disconnected while the amp is on, essentially what the switch does. Search the SSMH thread for more info.
> 
> I can't comment much on your original idea of doing away with the switch and connecting the analog RCA inputs in parallel with the DAC's output, except that I seem to remember reading somewhere that it's also a dangerous idea... maybe because of the possible ground conflicts?
> 
> cheers!


 

 Oops, I had forgotten about that little tidbit. However I don't think it will be a problem -
  http://www.head-fi.org/forum/thread/319231/millett-starving-student-hybrid-amp/5100#post_6509983
  It sounds like the problem occurs when the signal of the RCA touches the ground during disconnection/connection, not with disconnecting/connecting the DAC per se. If I keep the wiring clean I don't see how the switch will cause this to happen, so in theory it should be fine. That's assuming there's nothing wrong with the way I imagine the wiring in the first place (wiring the DAC output in series with regular RCA input, to allow for an optional RCA-in when the DAC is off).


----------



## tomb

Quote: 





ikarios said:


> Oops, I had forgotten about that little tidbit. However I don't think it will be a problem -
> http://www.head-fi.org/forum/thread/319231/millett-starving-student-hybrid-amp/5100#post_6509983
> It sounds like the problem occurs when the signal of the RCA touches the ground during disconnection/connection, not with disconnecting/connecting the DAC per se. If I keep the wiring clean I don't see how the switch will cause this to happen, so in theory it should be fine. That's assuming there's nothing wrong with the way I imagine the wiring in the first place (wiring the DAC output in series with regular RCA input, to allow for an optional RCA-in when the DAC is off).


 
  Actually, I think the_equalizer's analogy is correct - a DPDT switch would have the same effect as connecting/disconnecting the RCA jacks.  There's no guarantee that the static charge that might build up on the switch couldn't arc over the contacts and hit the DAC.
   
  The difference is that none of us knows if the grubDAC is susceptible, but after AMB announced trouble with the Gamma 1 and the SSMH, I'd be awfully careful.


----------



## Ikarios

Quote: 





tomb said:


> Actually, I think the_equalizer's analogy is correct - a DPDT switch would have the same effect as connecting/disconnecting the RCA jacks.  There's no guarantee that the static charge that might build up on the switch couldn't arc over the contacts and hit the DAC.
> 
> The difference is that none of us knows if the grubDAC is susceptible, but after AMB announced trouble with the Gamma 1 and the SSMH, I'd be awfully careful.


 

 Hmm... that doesn't sound so good. However since the SSMH has trouble with the Alien, Bantam, Gamma1, and possibly Grub, that's basically all the low-cost DIY DACs that are well-known here... I'll just be careful to not flip the switch of the DAC until the amp is off.
  I didn't expect arcing to be part of the problem, but if it's really a static leap/shock, that could cause problems. if the contacts on the SPST switch are isolated (by, say, heatshrink) it should be less of a problem, right?


----------



## cobaltmute

The Alien, Bantam and gamma1 are susceptible to the the issue with the SSMH in part due to the fact that the DAC chip (either PCM2702 or WM8501) is used without any stage after them.  In most of the higher end DACs there is a some sort of I/V stage or output buffer that handles whatever the SSMH is doing to the output stage.
   
  The grubDAC using the WM8524 has:
  Quote: 





> The device features ground-referenced outputs and the use of a DC servo to eliminate the need for line driving coupling capacitors


 
  It is unknown how this will handle the issue that occurs with the SSMH.  And unfortunately, they only way to tell is to try and kill a grubDAC (if you can reliably create the failure case) or just wait and see that nothing dies.
   
  All my personal stuff is wired together with 1/8" TRS.  I always turn my amp off when changing source, as a just in case measure.  It never hurts.


----------



## tomb

Quote: 





ikarios said:


> Hmm... that doesn't sound so good. However since the SSMH has trouble with the Alien, Bantam, Gamma1, and possibly Grub, that's basically all the low-cost DIY DACs that are well-known here... I'll just be careful to not flip the switch of the DAC until the amp is off.
> I didn't expect arcing to be part of the problem, but if it's really a static leap/shock, that could cause problems. if the contacts on the SPST switch are isolated (by, say, heatshrink) it should be less of a problem, right?


 

 Just adding to cobaltmute's input, I noticed your statement about the switch.  I was _not_ referring to the switch lugs (what you solder to), but rather, the contacts on the inside of the switch.  You basically only have a lever that presses together two metal bands on the inside and moves from one side of those bands to the other in throwing the switch.  The question is how much contact they have before and after moving the lever - that's in the "make-or-break" design of the switch and the contact voltage rating, I believe.  Bottom line, I think a static charge has a real good chance of crossover on the switch's insides.
   
  Further, just because the amp is off doesn't mean the static charge has gone away - it won't until it gets grounded by something.


----------



## cobaltmute

I realized I forgot to mention another point:
   
  The grubDAC inherently has a current limiting resistor at its output as part of the RC filter.  This may help in repelling the touch of death from the SSMH.


----------



## Ikarios

Just to clarify, the [SPST] switch I plan on installing will go in place of J1 on the Grub (as suggested here: http://www.head-fi.org/forum/thread/445155/the-grubdac/360#post_6734589 ), NOT as a source selector. The idea was to add an on/off switch to the grub to make my life easier when switching between headphones and speakers on my computer. I didn't think the SSMH killing issue would affect THAT switch... right?
   
  An input selector would have been a good idea but you guys are making me nervous about the whole thing. Here's a crude drawing of what I want to do:
  http://img180.imageshack.us/f/grub.jpg/
   
  the outputs of the grub would be connected directly to the RCA inputs, which then connect to the SSMH as usual. I don't really plan on using the RCAs anytime in the near future, but I'm adding them in case I want to upgrade to a better DAC or something in the future.
   
  I'm really sorry if I'm being difficult, but this is my second DIY project and I *really* don't want anything to go wrong. I'm quite concerned about this death-touch thing, but I also want to save money (being a starving student and all), and I want to stop changing my mind between one enclosure or two... thanks!


----------



## nate911

Just finished my Grub. Really good kit and packaging TomB. Sounds great, thanks!


----------



## tamu

just got a card from Royal Mail asking me to pay £12.11/$18.5 for customs and handling charge.. so annoying when the actual cost of the kit is 35usd!!


----------



## cobaltmute

Quote: 





ikarios said:


> Just to clarify, the [SPST] switch I plan on installing will go in place of J1 on the Grub (as suggested here: http://www.head-fi.org/forum/thread/445155/the-grubdac/360#post_6734589 ), NOT as a source selector. The idea was to add an on/off switch to the grub to make my life easier when switching between headphones and speakers on my computer. I didn't think the SSMH killing issue would affect THAT switch... right?
> 
> An input selector would have been a good idea but you guys are making me nervous about the whole thing. Here's a crude drawing of what I want to do:
> http://img180.imageshack.us/f/grub.jpg/
> ...


 

 I don't know if I like the output of the grub connected to the RCAs all the time.  In some of the prototyping I've done for other projects, I've seen powered down gear do some weird stuff like pass audio intermittently.  You never know what might happen when you put a signal on the RCAs. I think it would be better to have DPDT switch to switch between two inputs
  
  Quote: 





tamu said:


> just got a card from Royal Mail asking me to pay £12.11/$18.5 for customs and handling charge.. so annoying when the actual cost of the kit is 35usd!!


 

 I recently had the same thing ordering something from the US - $12 brokerage for a $24 item.  And there was no customs or duty.


----------



## jdkJake

So, today was an interesting afternoon.
   
  I have come to the conclusion man was not adequately equipped for SMD work!  
   
  So, I built my first grubdac today. For the most part, it went well, Not to say there were no frustrations, but, I was able to complete the build and the end product is functional (yeah!).
   
  Biggest obstacle? My poor aging eyes. This was the setup I used to actually do the build. I know. pathetic, but, what can I say, my eyes are not what they used to be.
   

   
  This was the end result. Actually worked on the first power up with my MOSFET-MAX. I was amazed and impressed at the same time. 
   

   
  So what did I learn?
   
  1) You really have to learn your own SMD technique. I actually had a much easier time with the IC's than those sadistic little MoFo capacitors and resistors. The real mind bender is the solder to flux ratio, which, is wrong on so many levels. I have NEVER used that little solder and that much flux! Seriously, the smallest amount of solder will get the job done. Be sure to use the back-light techniques outlined on the grubdac site.
   
     http://www.diyforums.org/GrubDAC/GrubDACphoto-build-1.php
   
  I caught a bridge using this technique. The board is REALLY well constructed. Kudos to cobaltMute and TomB for a forward-thinking design. I also found TomB's technique for the caps to solder one side, then place, then solder the other side worked really well once you got the hang of it.
   
  2) For me, the hardest part was opening the damn containers the SMD parts were in. I am a guy who hates long fingernails. For this job, they are almost a requirement to get the parts out of their containers. Truly, the sadistic MoFo who designed those shipping containers is laughing hard at the misery entailed to open them. If I ever meet him, I will bloody his nose. I will, I swear.  
   
  3) TomB is some kind of freak'n Zen master! Anyone who can put a hundred of these kits together and actually deliver, well, I am not worthy. He obviously functions on a higher level as my patience was stressed hard dealing with the myriad of tinier-than-tiny parts. Hats off to you sir!
   
  4) DO NOT SNEEZE!! I can not emphasize this enough.  These parts are ridiculously small. Seriously. Think of the smallest thing you have ever seen. That is still too big.
   
  So, would I do it again? I have no choice, I bought another one to put together!   
   
  Seriously though, I am glad to say I did it, but, I have to question how many builds I will do like this. Through-hole is just SO much easier.
   
  So far though, sounds great!!
   
  Thanks CobaltMute and TomB!


----------



## tomb

Ha!  Good job, though, jdkJake.  That PCB almost looks like it came through a pick and place machine.  Very nice!
   
  Did you use tweezers?  I don't see any in the pics and honestly, I can't imagine building SMD without them.  What's not mentioned in any of my support articles is that the tweezers are ideal for opening the SMD parts package (pulling back the tape covering the part so that it falls out on the building board).
   
  EDIT: Oh!  Thank you for the kind comments on the kit organization!


----------



## jdkJake

Quote: 





tomb said:


> Did you use tweezers?  I don't see any in the pics and honestly, I can't imagine building SMD without them.  What's not mentioned in any of my support articles is that the tweezers are ideal for opening the SMD parts package (pulling back the tape covering the part so that it falls out on the building board).


 

 I forgot to mention that! Thanks for bring this up TomB (and for the kind words as well).
   
  These are by far the MVP of the whole operation:
   

   
  There is absolutely NO WAY you can do this build without these (or their equivalent). Did I mention how small the parts are?  
   
  Seriously, these were like $4 bucks at mouser ($3.74 if you are picky). Essential to success. I have no idea how you could accurately place the parts without needle tweezers like these. A must have. That and the $2.99 dollar "helping hands" with magnifying glass from Harbor Freight. Unfortunately, I had to augment mine with my old standby Rat Shack "helping hands" that, while expensive, are actually much better built and more flexible than the HF version. Both are good though. You cannot go wrong with either (or both in my case).
   
  Oh, and one more thing, corrective lens as age requires...


----------



## cobaltmute

Quote: 





jdkjake said:


> The board is REALLY well constructed. Kudos to cobaltMute and TomB for a forward-thinking design. I also found TomB's technique for the caps to solder one side, then place, then solder the other side worked really well once you got the hang of it.


 
   
  Part of my goal when doing the layout for the board was to consider how to place the parts.  As I was laying out the board, I stared at it to know how I would go about placing the parts on the board.  Now, when you staring at the board on full size on a 24" monitor, your sense of perspective is a little off, but it still worked out in the end.
   
  I use a magnifier light like this:

   
  My face is literally right in the light as I'm working.  I'm not the youngest either and I've had bad eyesight since I was in Grade 2.


----------



## KeeChoon

I have received my kit this week and thanks to cobaltmute and tomb for offering the kit. Finished building it yesterday and had checked the possibility of bridges on the chips while building but I still end up with problems. There is no LED power up upon plugging in and there is no reading at the 3V3 test point. No detection in windows upon plugging in too. Have gone through the board to check for errors but can't seem to detect anything yet. I have attached the pictures below in case I miss any mistakes. Any help or advice is greatly appreciated, thanks!


----------



## jdkJake

Wow, your solder technique is excellent! Seriously, it looks fine at first glance.
   
  Can you take some measurements? Specifically, can you measure the +5 and +3 points?
   
  As for the LED, well, that depends on the orientation, which, judging by the rest of your build is probably oriented correctly. In any case, it should not effect the sound.


----------



## KeeChoon

Quote: 





jdkjake said:


> Wow, your solder technique is excellent! Seriously, it looks fine at first glance.
> 
> Can you take some measurements? Specifically, can you measure the +5 and +3 points?
> 
> As for the LED, well, that depends on the orientation, which, judging by the rest of your build is probably oriented correctly. In any case, it should not effect the sound.


 
   
  Thanks 
   
  Have measured and there are no voltage readings from both points. Thinking that it might be my PC, I had even tested on another PC at home. Had also switch from the USB cable to the mini connector and tried various cables, still no luck.


----------



## particleman14

get a ton of flux and reflow almost all of your resistors and capacitors.  I had a similar problem and i just went over every joint making sure there is a solid connections between the pads and the leads.  the fact that I can clearly see the edges of your smd parts means you might want to dab a bit more solder so it is more concave like the top of your R5 or left side R6.  get a loupe to inspect to make sure you have solid connections on each parts.  Another good test is to get a little rough and try to lift your smd parts w/ tweezers off the board w/ moderate pressure.  this will quickly expose any weak joints as they'll rip out!


----------



## tomb

Quote: 





keechoon said:


> Thanks
> 
> Have measured and there are no voltage readings from both points. Thinking that it might be my PC, I had even tested on another PC at home. Had also switch from the USB cable to the mini connector and tried various cables, still no luck.


 

 The 5V point is a direct trace from the connector.  If you can't even get 5V at the "5V" point, then it seems there has to be something wrong with the connector.  There's one solder joint that looks a little suspect for the connector.  Maybe reflow that and make certain none of the joints are touching one another?  Sometimes the pins get bent on those tiny Mini-USB's, too.  Is it possible that some of those joints don't really have one of the pins in them?
   
  Just some suggestions ...


----------



## KeeChoon

Have just reflow the joints, passive components and the chips. Still not getting any reading any voltage reading at either 5V or 3v3 even with the USB cable instead of the mini connector. There are voltage reading from the cable before installation onto the board so I assume that the USB points at the PC is working fine. What is werid is that once on the DAC board, no voltage reading. Is it the regulator?


----------



## particleman14

if you're not getting a 5V reading then check your usb connector..  if u have a spare usb cable you can cut it and wire directly to the board to test.  like the grub cabledac.


----------



## KeeChoon

Quote: 





particleman14 said:


> if you're not getting a 5V reading then check your usb connector..  if u have a spare usb cable you can cut it and wire directly to the board to test.  like the grub cabledac.


 


 Had did that with another cable which i wired directly to the board. As mentioned earlier that there was voltage when measure at the exposed leads before soldering onto the points on board but once on board, no reading. What are the chances of frying the ICs in this case?


----------



## particleman14

Work on getting that 5V reading.. it is the most basic starting point.  It is very odd if you measured 5V on the usb cable before soldering but 0V after soldering...  the voltage shouldn't magically disappear..
  From your descriptions so far your ICs may not have gotten any juice to them yet..


----------



## cobaltmute

What OS are you using?
   
  If it is Windows, please check device manager and see if one of the USB ports is shut down.
   
  Also test resistance between the 5V and 0V pads with USB cable disconnected.


----------



## KeeChoon

Windows 7, none of the ports are down.
   
  Getting a reading of 0.4 when measuring 5v and 0v pad. Does this means a solder bridge somewhere?
   
  One more thing, are the bridges for the chip as described under the construction steps same as these?


----------



## ShinyFalcon

Is there continuity between 5V and 0V? If so, you have a short somewhere.


----------



## jdkJake

Sounds like a short to me.

 When you bypassed the mini connector in favor of the direct cable hookup, did you remove the connector or leave it on the board?


----------



## Ikarios

It's not likely, but is it possible that there's a bridge under the PCM2706 chip? I remember it used to happen to AlienDAC PCM2702 solderers - there would sometimes be an invisible bridge underneath the actual chip. I don't know if it happens with the grub and the 2706, but just a thought.


----------



## jdkJake

I would be more suspect of a bridge under the mini USB connector.

 Although anything is possible at this point. Removing the connector will be far easier then taking off that chip!


----------



## ShinyFalcon

Another thing to check is to make sure only one of the pins on the crystal is connected to the "shell." The shell is connected to ground. If the 3.3V connects to ground, that's another source of a short circuit.


----------



## jdkJake

Quote: 





shinyfalcon said:


> Another thing to check is to make sure only one of the pins on the crystal is connected to the "shell." The shell is connected to ground. If the 3.3V connects to ground, that's another source of a short circuit.


 

 Good point! There does appear to be a lot of solder on that part.


----------



## cobaltmute

I agree that there appears to be a bridge.
   
  The bridge however is before or including the 3.3V regulator.  The regulator has a current limit on it, so if there is short is after it (say the crystal or on one of the ICs), the LED will light, but there will be no reading at the 3V3 point.
   
  Having no reading at the 5V point indicates that the computer has shut down power to the port - that is why I wanted to check the port status.  0.4 Ohms between 5V and 0V seems low, but I don't have a grubDAC open and I've got 18 people coming to my house in an hour so I won't be able to check for myself until much later today.
   
  the top side soldering looks excellent.  Do you have a picture of the bottom side?


----------



## KeeChoon

Plugging it into my work PC running on Windows XP gives this error message, 'A USB device has exceeded the power limits of its hub port.' The port is shutdown after that and had to be reset to reactivate it.
   
  Have checked all ports for my home PC, no such error when plugging into the USB 2.0 ports only except for the one on the keyboard which is a USB 1.0 port and the same error occurs. However a check into device manager shows no error as above.
   
  Here's the picture of the bottom side,
   

   
  I'll give the crystal a check once I get off work. Seems that the pad above R3 have solder touching the metal part, it should be the ground pad right? Cause its harder to solder compare to the others. If this does not work, I'm going to desolder the connector n switch to cable see if it works. Will update later, thanks guys.


----------



## cobaltmute

Looking at your picture of the bottom, I'm concerned about C7.  Looking at it, on the side closest to the TPS regulator, it looks like there is solder down the whole side of the capacitor.  This would bridge the 5V to ground and cause the behaviour that your are seeing.  That cap does need to be there (as it is the input cap for the TPS regulator), but you could try removing it and running without it as a test (as it is in parallel with C5 and hopefully that is enough close enough to keep the TPS stable)


----------



## KeeChoon

Have desoldered the connector off the board, wired the USB cable directly to the board, clean up the solder at the crystal and reinstalled C7. Had also checked other components for bridges.
   
  Still no luck, no voltage at 5V, 0V or 3V3 pads. Now this is getting werid...


----------



## ShinyFalcon

- Check for continuity along the 5V line (use the schematic)
  - Is resistance across L1 low?
  - Check across all resistors and make sure they read their intended value
  - Check for shorts across the capacitors, C5 in particular
  - Make sure you're measuring correctly: one probe on 0V, the other on the 5V
  - Make sure none of the four USB lines have connection to each other (D+ to G, D- to D+, etc...)
  - Make sure the colors on the USB cable are correct: red white green black (5V, D-, D+, 0V)
  - Measure the continuity of your USB cable (refer to a USB pinout page)


----------



## jdkJake

You might want to back things off a bit and do what ShinyFalcon suggests.

 You could remove L1 and still see if you have a short. It is the earliest point in the circuit for delivering +5 to the board (I wired a switch across it for my application). if you still have a short, then you know you have eliminated the main path of power into the circuit. Hopefully, this makes probing easier.

 After that, without power to the board (be sure no power!), you need to slowly and methodically probe between +5 and ALL the other points along the circuit until you find the one that is shorted out. Work your way down the schematic as ShinyFalcon suggests.


----------



## cobaltmute

Taking another look now, it looks like there is some crud under the mini-USB joints.  Make sure that part of the board is totally clean.
   
  Remove L3 - see if the board powers up.  This isolates the regulator/input from the rest of the board.  If it still won't get 5V at that point, there there is something wrong with either the regulator or the caps around that portion. 
   
  Your work is very clean, and looks to be clear of bridges, so either there is a bridge under a part or it may be the TPS regulator that is shot,


----------



## KeeChoon

Ok, will go thru those tomorrow.
   
  No problems for the cable itself as prior wiring it onto the board, its supplying 5v w/o problems.
   
  So basically I will be looking at components from L1 to the point the 5V enters U2 right? C5, C7 and U2 itself for bridges, how about the LED and R5?


----------



## cobaltmute

All of those (including the LED).  Good point about the LED - you could have toasted it.  I have done this - so you could trying removing R5 as well to remove the LED from the circuit.
   
  U2 will shutdown its output if there is a short after it, but there will power at the 5V point.
   
  There is a via right under U2 to the top ground plane, so you have to check around it very carefully.


----------



## KeeChoon

Quote: 





cobaltmute said:


> Taking another look now, it looks like there is some crud under the mini-USB joints.  Make sure that part of the board is totally clean.
> 
> Remove L3 - see if the board powers up.  This isolates the regulator/input from the rest of the board.  If it still won't get 5V at that point, there there is something wrong with either the regulator or the caps around that portion.
> 
> Your work is very clean, and looks to be clear of bridges, so either there is a bridge under a part or it may be the TPS regulator that is shot,


 

 I have desoldered the mini USB connector and switch to wiring a USB cable to the board. Had gave the board another scrub prior to testing.
   
  Roger that, will check the board again as ShinyFalcon suggested and do the L1 and L3 test.


----------



## KeeChoon

Ok, have did all the test.
   
  Removing L1 sees 5V to at the input pads. Reinstalling L1 and removing L3 shuts the board down.
   
  Have also removed and reinstalled C5 and C7, no luck. Removing the LED and R5 also did not help.
   
  I had a spare U2 from another project and swap that in, taking care to prevent any bridges but still the same results.


----------



## cobaltmute

So between L1 and L3 there is a short to ground.  This is on the input side of U2 as well, as U2 current limits and shutdowns its output on a short on the rest of the board.
   
  What is the resistance between 3V3 and the 0V point?


----------



## KeeChoon

Resistance between 3v3 and 0v keeps climbing when measured, starts off at around a few K ohms. Is this normal?


----------



## Ikarios

A question slightly related to the Grub - I've been soldering PCM2702s (on the AlienDAC) using the flood-and-suck method, along with the drag-and-wipe method, but I'm not completely sure about how solid my soldering job is. If I use soldering wick to pull up solder from the outside of a pin, will it take solder underneath the pin with it? The reason I ask is because there's only visible solder bridging the pad and the pin on maybe half of my pads; the other half look like they just have the pin sitting on the pad. I'm not sure if there's solder underneath that pin (and therefore, continuity). I figure the flood-and-suck method would cover that but I'm not sure. Anyone?


----------



## jdkJake

keechoon said:


> Resistance between 3v3 and 0v keeps climbing when measured, starts off at around a few K ohms. Is this normal?







 Well, that leaves c8, c14 and c15 as the only parts on that side of l3 you did not resoldier. Might be worth removing and remounting those parts and then reinstalling l3.

 Still, it seems like the most likely bridge would be under u2. Interesting.


----------



## jdkJake

ikarios said:


> A question slightly related to the Grub - I've been soldering PCM2702s (on the AlienDAC) using the flood-and-suck method, along with the drag-and-wipe method, but I'm not completely sure about how solid my soldering job is. If I use soldering wick to pull up solder from the outside of a pin, will it take solder underneath the pin with it? The reason I ask is because there's only visible solder bridging the pad and the pin on maybe half of my pads; the other half look like they just have the pin sitting on the pad. I'm not sure if there's solder underneath that pin (and therefore, continuity). I figure the flood-and-suck method would cover that but I'm not sure. Anyone?







 Did you apply flux underneath the part before you dumped on the solder? 

 I would think you would be fine as only the smallest amount of solder is needed to insure a solid physical connection. As long as you used flux to insure the part heated properly and flowed the soldier AND did not move the part during the "suck" part of the process you should be fine.

 If you have needle tips for your multimeter and a steady hand with a careful eye, you should be able to measure for continuity between the pin and pad. Quite the "zen" task, but, it can be done.

 Otherwise, do your best to verify no bridges and test it out and see how it rolls.


----------



## jdkJake

BTW, ideally, you don't want solder under the pin. Or at least not as large an amount so as to lift the pin. Rather, you want a solid physical connection between the pin and pad. The solder is to re-enforce the joint, not make the joint. Although, in practice, I am sure that happens regardless. The soldier fills all the microscopic pits and valleys between the parts to form the final connection, both physical and electrical.


----------



## KeeChoon

Quote: 





jdkjake said:


> Well, that leaves c8, c14 and c15 as the only parts on that side of l3 you did not resoldier. Might be worth removing and remounting those parts and then reinstalling l3.
> 
> Still, it seems like the most likely bridge would be under u2. Interesting.


 

 Sadly I did C8, C14 and C15 too.
   
  By the way, L1 reads around 270ohms to 280ohms when plugged in.
   
  The werid thing is that I had replace a new U2 and the problem still persist. Any chances of a manufacturing defect for the board? Or passive components fried?


----------



## Juaquin

Quote: 





ikarios said:


> A question slightly related to the Grub - I've been soldering PCM2702s (on the AlienDAC) using the flood-and-suck method, along with the drag-and-wipe method, but I'm not completely sure about how solid my soldering job is. If I use soldering wick to pull up solder from the outside of a pin, will it take solder underneath the pin with it? The reason I ask is because there's only visible solder bridging the pad and the pin on maybe half of my pads; the other half look like they just have the pin sitting on the pad. I'm not sure if there's solder underneath that pin (and therefore, continuity). I figure the flood-and-suck method would cover that but I'm not sure. Anyone?


 

 Yes, solder should remain under the pin connecting it to the pad. Whether or not it's enough for a secure long-term connection depends on how much you removed. Personally I've never had anything but disastrous results with the flood and wick method. A bridge always ends up underneath some pins or somewhere that I miss. On all but the smallest of chips I simply use a small tip and solder normally. On smaller chips (like the PCM2707) I use the drag method with pretty good results.


----------



## cobaltmute

Quote: 





keechoon said:


> Resistance between 3v3 and 0v keeps climbing when measured, starts off at around a few K ohms. Is this normal?


 
   
  This is normal and expected.  What is happening is that C1 is uncharged and the meter is charging it and is increasing the resistance between the positive rail and ground.  This is good in that is shows that you have no bridges after the regulator.


----------



## cobaltmute

Quote: 





keechoon said:


> Sadly I did C8, C14 and C15 too.
> 
> By the way, L1 reads around 270ohms to 280ohms when plugged in.
> 
> The werid thing is that I had replace a new U2 and the problem still persist. Any chances of a manufacturing defect for the board? Or passive components fried?


 

 It could be a problem with the board or a passive component.
   
  Remove C3, C5, LED, R5, C7.  Measure the resistance between 5V and 0V.  This should be something not small.  If small, check all the traces for a connection between the + rail and the ground.  If it not small, place C7 back on the board.  Measure the resistance between 5V and 0V again - it should increase to the value you had the last reading.  Power up.  Hopefully you have life.


----------



## cobaltmute

Quote: 





ikarios said:


> A question slightly related to the Grub - I've been soldering PCM2702s (on the AlienDAC) using the flood-and-suck method, along with the drag-and-wipe method, but I'm not completely sure about how solid my soldering job is. If I use soldering wick to pull up solder from the outside of a pin, will it take solder underneath the pin with it? The reason I ask is because there's only visible solder bridging the pad and the pin on maybe half of my pads; the other half look like they just have the pin sitting on the pad. I'm not sure if there's solder underneath that pin (and therefore, continuity). I figure the flood-and-suck method would cover that but I'm not sure. Anyone?


 
   
  A lot of the pins I do on the PCM just look like the part is sitting on the board.  When you look at it with an 8X loupe (very usefully for this work and cheap to get), I can see that there is small layer of solder between the part and the board.
   
  The biggest thing to learn about doing SMD work is that you need about 1/4 of the solder that you think you do.


----------



## KeeChoon

Quote: 





cobaltmute said:


> It could be a problem with the board or a passive component.
> 
> Remove C3, C5, LED, R5, C7.  Measure the resistance between 5V and 0V.  This should be something not small.  If small, check all the traces for a connection between the + rail and the ground.  If it not small, place C7 back on the board.  Measure the resistance between 5V and 0V again - it should increase to the value you had the last reading.  Power up.  Hopefully you have life.


 

 The reading between 5V and 0V is very small. I removed L1 and there is voltage to the pads again. Measuring the resistance of the L1 pads to ground, the pad nearer to edge gives a reading on the meter, no readings from the top pad. Is this the issue?
   
  Think I found the problem. Looking at the positive pad of C5 under light, this means the positive pad is connected to the ground pane right? Does this mean the board is defective?


----------



## cobaltmute

If that stuff connecting the + pad of C5 to ground plane is not just solder on top, then yes, you have a board with a manufacturing defect.  This does happen on occasion.
   
  You can recover from this.  Pretty clear to see in front of the light what copper you need to remove.  Take an Xacto knife and cut away at the copper until you see a clear gap in the back lit view.


----------



## KeeChoon

Quote: 





cobaltmute said:


> If that stuff connecting the + pad of C5 to ground plane is not just solder on top, then yes, you have a board with a manufacturing defect.  This does happen on occasion.
> 
> You can recover from this.  Pretty clear to see in front of the light what copper you need to remove.  Take an Xacto knife and cut away at the copper until you see a clear gap in the back lit view.


 


 Yep its not the solder. Hopefully this is the problem. Will work on it and update the results. Thanks!


----------



## KeeChoon

OK problem solved! It is really the bridge at the positive pad of C5. The little unit is working fine now. Sounds great too!
   
  Thanks all for the help!


----------



## cobaltmute

Success is good to hear


----------



## jdkJake

That's great to hear KeeChoon! Glad you got it up and running.

 While I am sorry you had to go through that, I really learned a lot about the grubdac through the process. So, I am glad you were patient enough to see it though.


----------



## Aalelan

Quote: 





jdkjake said:


> That's great to hear KeeChoon! Glad you got it up and running.
> 
> While I am sorry you had to go through that, I really learned a lot about the grubdac through the process. So, I am glad you were patient enough to see it though.


 

 Ditto!!!  Now I know how the power routes through that thing..  Glad you got it running man!!!
   
  AA


----------



## cobaltmute

Power routing is pretty easy to figure out on the production board - look for the thicker traces.  I kept the power traces 30 mil while signal traces were 15 mil IIRC.  And of course the ground plane is one the top.


----------



## Aalelan

What software do you use Cobaltmute?  I'm trying to find some semi-intuitive software I can lay some designs out and try to make some simple boards...
   
  Thanks!
  AA


----------



## cobaltmute

I'm using Electronics Workbench 10.1

 I don't like Eagle. I've heard DipTrace is not too bad


----------



## Avro_Arrow

I use Eagle. I'm not really that fond of it but it is free...
  I just downloaded AutoTrax, the free version is limited
  to 100 pins though.
  I have lots of experience with ExpressPCB but it is
  only any good for that boardhouse.
  
  Quote: 





aalelan said:


> What software do you use Cobaltmute?  I'm trying to find some semi-intuitive software I can lay some designs out and try to make some simple boards...
> 
> Thanks!
> AA


----------



## Fred_fred2004

For what its worth, I use PCBartist from
   
http://www.4pcb.com/
   
  its free and very simple for layouts, no good for gerber but I make my own boards so no biggy
   
  designing your own parts is very simple
   
  cheers
  FRED


----------



## MrDavis

I finished my grubcableDAC tonight.  I hooked it up to my minimax and my computer to see if would work... it didn't.
   
  I'm getting this error message from windows 7:


----------



## cobaltmute

It looks like you may have solder from the pads to the top of X1. This will cause a bridge to ground and give you the type of issue you are seeing. ALS o try pitting the board in front of a light and look for bridges on the PCM2706


----------



## tomb

Quote: 





cobaltmute said:


> It looks like you may have solder from the pads to the top of X1. This will cause a bridge to ground and give you the type of issue you are seeing. ALS o try pitting the board in front of a light and look for bridges on the PCM2706


 

 Good call!  I wonder also if the top left joint (oriented in the pic) of the oscillator is actually making a connection.  Some de-soldering braid and plenty of flux should work well to clean the solder from the top.


----------



## MrDavis

Quote: 





cobaltmute said:


> It looks like you may have solder from the pads to the top of X1. This will cause a bridge to ground and give you the type of issue you are seeing. ALS o try pitting the board in front of a light and look for bridges on the PCM2706


 
   
  Quote: 





			
				tomb said:
			
		

> Good call!  I wonder also if the top left joint (oriented in the pic) of the oscillator is actually making a connection.  Some de-soldering braid and plenty of flux should work well to clean the solder from the top.


 
   
   
  A little bit of rework and Success!  Its working now. Solder wick is amazing and so is the sound coming from the grubdac.
   
  Thank you very much for your help cabaltmute and tomb!


----------



## fooby

I finished my GrubDAC and put it into one of those Eclipse tins. I did it with the BantamDAC too previously for a few months, but only came up with the USB socket solution a month ago. So here goes:
   
  USB socket assembly on veroboard

   
  GrubDAC PCB all wired up

   
  Nobody's going to see the ugly dremel job here 
, 
   
  USB socket attached and secured

   
  At this point just mash the pcb into the tin and feed the 3.5mm socket and LED into the holes

   
  And commence listening!

   
  The GrubDAC worked first time without problems...excellent outcome, having previously attempted two BantamDACs, one which failed and one which sort of works but with strange cutout issues. Maybe my soldering's getting better.
   
  Thanks to all involved in designing, producing and "kitting" (must have taken a seriously long time to package all those kits) - real fun little project!


----------



## Ikarios

Wow fooby, that's a pretty cool implementation! I wish I had seen that when I was coming up with my USB method - I'm using a Neutrik USB-A -> B adapter to panel mount the USB, then using a USB A -> miniB to hook it up to my Grub. Needless to say it's a pretty clunky method...


----------



## fooby

Hey, thanks Aflac 

   
  I kept trying to think of ways to panel mount a USB socket for months, since those neutrik plugs are massive (and expensive). It finally came to me when I was doing some tidying and came across some old veroboard...


----------



## cobaltmute

Nicely done fooby.


----------



## the_equalizer

That's some seriously cool DAC you built !  Congratulations !  You should post the pics on the 'Show us your build'  thread.


----------



## jdkJake

Nice job! Very clean look. 

 What did you use on the bottom of the board to keep it from shorting out?


----------



## Ikarios

Just confirmed my own GrubDAC is working, although it's quite messy since I haven't figured out exactly where I'm going to place it in my SSMH case (hence the long leads). I'm happy to say that the method of adding a switch and an in-line ferrite in place of L1 works like a charm. It only took me about two hours total to get all the components on this board, so I was quite shocked when it worked perfectly at first power-up - maybe I prefer SMD work after all...
  I went with SMD C16/C17 caps instead of film caps, saved myself a dime and didn't have to work with nasty through-hole... 
	

	
	
		
		

		
			





 hopefully there's no harm to the sound quality in the SMD caps, because it seems like everyone uses the box caps.
   

   

   
  more pics here: http://picasaweb.google.com/submergence/GrubDAC#


----------



## fooby

Quote: 





jdkjake said:


> Nice job! Very clean look.
> 
> What did you use on the bottom of the board to keep it from shorting out?


 
   
  I just stuck some electrical tape on the bottom of the pcb. Would have been a bit better to line the tin with tape instead though (too lazy now).
   
  Also I probably should have put heatshrink on the stereo socket lugs too, since they extend inside the case a bit.


----------



## funch

Thought I'd link to some pix of my build. Posts 6223 and 6225. I've since changed the electrolytic cap's
  to 330uF FM's.
   
http://www.head-fi.org/forum/thread/233941/new-millett-hybrid-maxed-amp/6210


----------



## jdkJake

funch said:


> Thought I'd link to some pix of my build. Posts 6223 and 6225. I've since changed the electrolytic cap's
> 
> 
> to 330uF FM's.
> ...







 Notice any difference in sound quality?


----------



## funch

I didn't really listen much with the original cap's, so I can't really say.


----------



## jdkJake

Regarding the capacitor tweak, I have a question for cobaltMute:
   
  You recommend trying a low ESR aluminum electrolytic cap with a lower leakage current in place of one with a "super-low" ESR (but more leakage current). As I understand it, the ESR represents the the resistance outside of the leakage path (acts like a resistor in series to an ideal cap). So, do you believe the extra leakage current of the "super-low" ESR cap is increasing the potential ripple current through the capacitor and/or adding to the noise? Since ESR is most prominent at high frequency (or high current), do you believe the trade-off in lower leakage current offsets any benefit from lower ESR, which technically, might not even come into play at lower frequencies?
   
  I would value your opinion on the topic. I am trying to learn more about power supplies and see "super-low" polymer ESR caps being utilized more and more around DC-to-DC regulators, especially in digital environments. Are there noise artifacts that "super-low" ESR polymer caps can deal with better than low ESR electrolytics?


----------



## cobaltmute

What I've learned about noise from capacitors, I've learned from reading over at DiyHiFi.  When someone like Jocko Homo says that leakage through a capacitor causes noise, I have a tendency to believe him.  When several others follow with that thinking, that thinking gets some more weight.
   
  I won't pretend that I understand all of the mechanics of it.  But it would seem to follow that the more current that you have passing through a device, the more noise that current can produce.  Very similar in a way to Johnson noise.
   
  There is a trade-off to that though, that is best explained in this post:
http://www.diyhifi.org/forums/viewtopic.php?p=42605#p42605
   
  So super low ESR caps are useful due to the low impedance that they keep at higher frequencies,  And everything I've read about power supplies says that you want low impedance as much as you can.  That's why people like OS-CONS.  Solid Polymer and low leakage current.  But they get large for larger values and then you need board space and case height.
   
  So what do you do?  It is all a trade-off for the type of circuit that you are powering.  Is the capacitor a decoupling or bulk filtering capacitor?  Is it following a part that needs super-low ESR?
   
  So does that explain anything?
   
  And like all of you, I'm learning every day.  So I'm open to being proved wrong by someone with more knowledge (and there are a few that come to mind that could do that to me).  I always seem to learn more when I get things wrong.


----------



## barsk

Hi, as a newbie just starting SMD soldering, I am about to do this on my (two) GrubDAC kits that I recently got.
  I have most of the theory of how to do it covered besides one thing. What temperature do you set the soldering ioron to (I have a temperature controlled one)? As these litte buggers are easy to burn up I guess setting the temp about right is crucial.
   
  Also, what temp do you set for the other soldering work with standard through-hole components?
   
  I do understand that different jobs calls for different temperatures, like soldering cables and thicker copper plates etc. What I am looking for is some baseline settings to get me started. Finding this info on the net has proved difficult to sat the least...


----------



## tomb

Quote: 





barsk said:


> Hi, as a newbie just starting SMD soldering, I am about to do this on my (two) GrubDAC kits that I recently got.
> I have most of the theory of how to do it covered besides one thing. What temperature do you set the soldering ioron to (I have a temperature controlled one)? As these litte buggers are easy to burn up I guess setting the temp about right is crucial.
> 
> Also, what temp do you set for the other soldering work with standard through-hole components?
> ...


 

 I usually have my Hakko set to 375 deg.C. for through-hole soldering and turn it down to 325 deg.C. for SMD.
  
   
  EDIT: Nope, my original numbers were OK - you guys needlessly scared me.  I'm correct!


----------



## cobaltmute

The choice of temp for your iron will in part depend on your solder - higher temp are required for lead free solder, say 700F.  I keep my iron down at 600F unless I'm doing rework and need some more heat to remove parts, but am using leaded solder.


----------



## Ikarios

wow, 325C? I've been doing my soldering at 750-850C (EDIT: Fahrenheit, whoops)... 
	

	
	
		
		

		
		
	


	




 I try not to touch parts for longer than two or three seconds if I can. I didn't think my solder (Kester 63SN/37PB) even melted until around 400-500C. When I did soldering at 550C (Fahrenheit) it was a PITA, the solder didn't flow well and didn't want to stick to anything. Turning up the heat and using water-soluble flux made things a lot easier.


----------



## Aalelan

Speaking of water-soluble flux I have never used it, I see on digikey these two.. [size=small]KE1808-ND[/size] and [size=small]KE1804-ND[/size], what does one look for in buying this?
   
  Thanks!
  AA


----------



## tomb

Quote: 





ikarios said:


> wow, 325C? I've been doing my soldering at 750-850C...
> 
> 
> 
> ...


 

 Forget it (my edits) - I'm correct!
   
  See this: 
	

	
	
		
		

		
		
	


	




  Note that the lower numbers (in gold) are Celsius, while the higher numbers (in white) are Fahrenheit.  So, ~325 deg.C. is about 617 deg.F.  I try to get away with the lowest temp that I can and still produce good, dependable joints.  It saves the parts and the PCB that way.
	

	
	
		
		

		
		
	


	



   
  Some of this depends on the tip and the ground plane in the PCB.  I have, on occasion, adjusted to about 25 deg (Celsius) higher to get a particularly stubborn joint, but those are the settings I've used for everything I've ever built.
   
  EDIT: Once you guys do the Celsius-Fahrenheit conversion
	

	
	
		
		

		
		
	


	




, you'll note that my settings agree almost dead-on with Cobaltmute's (he quoted Fahrenheit numbers).


----------



## cobaltmute

Quote: 





ikarios said:


> wow, 325C? I've been doing my soldering at 750-850C...
> 
> 
> 
> ...


 

 I think you have a units issue there.  You're likely soldering at 750F (which is fairly high)/


----------



## Ikarios

Quote: 





cobaltmute said:


> I think you have a units issue there.  You're likely soldering at 750F (which is fairly high)/


 

 yeah, I thought about that for a second... 750C would be unbearably hot. but yes I've been soldering at 750/850F, but all four of my SMD boards (three aliens and one grub) are working. Maybe I'll try turning the iron down to the settings you guys are running at and see if that works better.


----------



## cobaltmute

Well it also has to do with your solder.  Lead-free needs about 700 to melt quickly or at least the small chunk of stuff that I have does.  For leaded solder you can run at a lot lower temp.


----------



## jdkJake

Thanks for the links cobaltMute. I will have to read them over to learn more.

 I guess I never pictured dc-to-dc regulation as a high frequency problem, but, apparently, there are artifacts from digital noise that need to be considered. I need to read up more on the topic.

 Thanks again for answer!


----------



## barsk

Quote: 





tomb said:


> Â
> 
> I usually have my Hakko set to 325 deg.C. for through-hole soldering and turn it down to 375 deg.C. for SMD.
> Â
> ...


 
   
  You mean 325 C for SMD and 375 C for through-hole, right?
  I've had mine at about 345 C for standard through-hole soldering so I have been about right there so far I guess.


----------



## tomb

Quote: 





barsk said:


> Â
> Â
> You mean 325 C for SMD and 375 C for through-hole, right?
> I've had mine at about 345 C for standard through-hole soldering so I have been about right there so far I guess.
> Â


 

 Yep - I screwed it up after editing it a couple of times when everyone panicked at my numbers.  The photo should take care of it for good, though.


----------



## barsk

Ok, thanks for the clarification. And thanks to all who contributed to the answers,
  Now, I only need that solder I mentioned (63/36/2), flux pen and flux desolder wick to be delivered and I am good to go. I really am eager to get that GrubDAC in shape.


----------



## barsk

I have another question regarding the grubDAC and really USB dacs in all. Is there any chance that I get bit-perfect digital transmission from the computer with this device by default? Or is it the same troubles as usual meaning I need to look into ASIO, reclock etc to get it right?
   
  Second question. Is the digtial transmission synchronized or asynchronized?
   
  I have read a little about the HRT Music Streamer that has been getting some great review. As I understand it it uses a buffer to completely separate itself from the clock the transmission uses. Then it uses its own clock to reclock the data and by that minimizes jitter completely . I.e it uses an async transmission with buffering and then delivers the data with its own really accurate clock to the internal DAC.
  From reading the schematics and technical papers it seems the grubDAC uses a synchronized transmission method. Right?
   
  If there is indeed an advantage with the async mode, is there any chance we might see such a project? The next DIY super DAC...


----------



## cobaltmute

Bit perfect from the grubDAC depends upon your music player.  For Windows 7, I use foobar2000 with the WSAPI plugin.  This bypasses the kernel mixer in Win7 and ensures bit perfect.  For XP you'd want to use ASIO to ensure bit perfect.
   
  The PCM2707 is a synchronous chip.  The clock for the USB communication is the treated to a PLL to create the clocking for i2s to the WM8524.  That being said, I have read elsewhere and it seems to be the case that the better the clock feeding the PCM2707, the better the sound.  This was part of the reason for using the Crystek clock (reported as very good) versus using a crystal for the clock functions on the board.  For the record, the other reason was build-ability - using a crystal would have placed it in a spot that made rework difficult.
   
  As for asych, I've looked at it.  It is a much more complex solution as it requires a chip like the TAS1020B and some hardcore development of code.  There are other options, but they are hard to come by.  A good low jitter 44.1kHz USB to I2S asynch design would be great for a project I have.


----------



## barsk

Ok, thanks for the clarifications.
  I use Spotify a lot for my music and it is a streaming solution with a dedicated player not enhanced with bit-perfect solutions. So getting bit-perfect is not that easy. I have been trying VAC with some success though.
   
  I guess we will have to wait a little more for a asynch solution then. Btw, I am a programmer, and I have been looking into PIC programming a little. Maybe a joint effort could come to a solution here. That said, programming low level ASM code is not what I do usually. Normally I am programming in Java. But, how hard can it be to shuffle a little bit of data...


----------



## limpidglitch

Finally finished the enclosure for the Grub I started on more than a month back.
   
  Voilà:


----------



## cobaltmute

Are we seeing the bottom of that?  Looks like stained wood, with maybe a cloth top...
   
  Very nice.


----------



## limpidglitch

Yes, yes, yes and thank you.
   
  Fixed a second picture.


----------



## MrDavis

My GrubDAC with my MiniMax.


----------



## tomb

Quote: 





mrdavis said:


> My GrubDAC with my MiniMax.


 

 Very nice - looks exactly like my typical setup!


----------



## the_equalizer

Quote: 





limpidglitch said:


> Finally finished the enclosure for the Grub I started on more than a month back.
> 
> Voilà:


 

 Very elegant looking, I really liked it. Congratulations!

  
  Quote: 





mrdavis said:


> My GrubDAC with my MiniMax.


 

  
  Quote: 





tomb said:


> Very nice - looks exactly like my typical setup!


 

 Very similar to mine too, though these last two weeks I've been using the GrubDAC with my 17EW8  Millet "Starving Student" at the office. Great sounding combo IMHO, particularly with Grado cans.


----------



## Ikarios

So I've been using my grubDAC for about a week now, and I'd have to say it's pretty nice. I can't quite comment on sound yet, given that I have no real way to test yet, but I'll figure that out in the meantime.
   
  Anyway, is there a way to turn down the sound output from Windows 7? the native volume control does nothing and at full volume my SSMH gets quite loud very quickly (too loud not long after 9 o'clock), but I have some pot imbalance around 8:30. I turn down my foobar sound so I can use the volume at higher levels, but Windows sounds get very very loud at this point.


----------



## cobaltmute

Click on your Volume Icon in the system tray and then click on Mixer.  You can adjust your sounds per application.
   
  Also use foobar with the WSAPI plugin, and select the WSAPI device in the output of foobar.  This locks the output to the grubDAC to foobar and makes the Windows sounds go to another sound output device if you have one.


----------



## luvdunhill

I had the opportunity to build yet another one of Tom's kits, what a pleasure! Nice work guys!
   
  One recommendation, if I can be so bold. I don't have a problem with pad-in-via in general, since these are being built by hand. One recommendation I'd have would be to move the vias where possible to the part of the pad under the various parts and to consider using tented vias (and moving the via a bit further from the pad) where this isn't possible. Smaller vias would be possible as well, given the tolerances between traces used on the rest of the board. One great example would be the shared via off the Wolfson chip, where the solder likes to blead over and look like a bridge between the two pads. Solder stealing isn't as big of a problem as it would be if these were being produced in a mass scale, but IMHO it will produce a nicer looking board


----------



## tomb

Quote: 





luvdunhill said:


> I had the opportunity to build yet another one of Tom's kits, what a pleasure! Nice work guys!


 

 Thanks for the kind comments on the kits!


----------



## cobaltmute

Quote: 





luvdunhill said:


> I had the opportunity to build yet another one of Tom's kits, what a pleasure! Nice work guys!
> 
> One recommendation, if I can be so bold. I don't have a problem with pad-in-via in general, since these are being built by hand. One recommendation I'd have would be to move the vias where possible to the part of the pad under the various parts and to consider using tented vias (and moving the via a bit further from the pad) where this isn't possible. Smaller vias would be possible as well, given the tolerances between traces used on the rest of the board. One great example would be the shared via off the Wolfson chip, where the solder likes to blead over and look like a bridge between the two pads. Solder stealing isn't as big of a problem as it would be if these were being produced in a mass scale, but IMHO it will produce a nicer looking board


 
   
  Part of the choice of the via drill sizes has to do with production and the ability to use someone like BatchPCB (and therefore GoldPhoenix) for test boards.  The vias are 15mil, which is there minimum drill size.  They are actually smaller than the 20mil min that BatchPCB used to spec, but they still produced the board.  Admittedly, I could make a smaller annular ring around the via.
   
  As for tenting, there is doing it the right way, the wrong way and then not doing it.  The right way is having the fab shop cap the via, then soldermask it.  The wrong way is to just soldermask it - which a lot of people do.  And there is not doing it, which is what I ultimately set the design for.  The best way to do it is actually to have the via filled with solder and then soldermask, but the best way makes boards expensive.

 I could move some of the vias into the pads for better looks.  When I was working on the board, my mindset was to give the most pad area for soldering as you never know who might be working on the board (and this includes myself).  Those "bridge" vias are a useful place to leave that extra bit of solder as you do the drag and wipe method of SMT soldering.  If it was going to be a mass produced board, then it could go with smaller caps and then via in pad becomes a problem due to tomb-stoning.


----------



## luvdunhill

I prefer the "wrong" way as you say to do tented vias... Actually, I learned this when I was still using EAGLE and read this rather nice writeup by Sparkfun:
   
http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=115
   
  I'm surprised people use drag and wipe on this pitch, I just solder pin by pin. It's not really that fine, IMHO.


----------



## tomb

Quote: 





cobaltmute said:


> ... and then via in pad becomes a problem due to *tomb-stoning*.


 

 Ha, ha ... 
	

	
	
		
		

		
			









  
  Quote: 





luvdunhill said:


> I'm surprised people use drag and wipe on this pitch, I just solder pin by pin. It's not really that fine, IMHO.


 

 True - and that's how I soldered many of the pins on some of the ones I built, but still ... I'm sure cobaltmute was shooting for the masses and soldering these chips are still quite a challenge to many people.  In those cases, "drag and wipe" seems the best method to guarantee success.  To tell the truth, I'd never thought about it, but having the vias way out on the end of the pads seems to ensure that they never get in the way - especially if you're having any trouble with bridging.


----------



## jdkJake

This is how I am using mine:
   

   
  Mounted inside my MOSFET-MAX:


----------



## cobaltmute

Quote: 





luvdunhill said:


> I prefer the "wrong" way as you say to do tented vias... Actually, I learned this when I was still using EAGLE and read this rather nice writeup by Sparkfun:
> 
> http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=115
> 
> I'm surprised people use drag and wipe on this pitch, I just solder pin by pin. It's not really that fine, IMHO.


 
   
  I've read the Sparkfun article, and many others.  Lots of stuff you can dig up in Google.  The issue, in my opinion, is that if the tent breaks, you know have let air in on bare copper and are oxidizing a prime portion of the board as HASL is applied after soldermask.  And the quality of the tent is dependent on the quality of the solder mask.
   
  Now don't get me wrong, I *love* the look that can be obtained with tented vias.  But I'm a bit of a perfectionist, and I'd like to do it right or not all.  And you all don't want to pay the price for boards with filled vias.  Why do you think all the through-hole component labels are under the parts?  I like  the look of a clean board.  If these were machine populated boards, I'd have no silkscreen on them at all.
   
  As for drag and wipe, I just put a small blob on my iron and hit 5-8 pins with one drag across.  Just my technique.  And I never use wick as I've learned to control how much solder to use.  Solder pin by pin would be so time consuming.


----------



## cobaltmute

Nice work jdkJake.


----------



## jdkJake

Thanks, 
   
  BTW, I think this DAC sounds a lot better since I removed the switch I originally had across L1 (both with and without a ferrite). Seems to resolve a lot better in the "as built" configuration. 
   
  Originally, I wanted the power switched when selected, but, this implementation is a lot cleaner.


----------



## tomb

Quote: 





jdkjake said:


> Thanks,
> 
> BTW, I think this DAC sounds a lot better since I removed the switch I originally had across L1 (both with and without a ferrite). Seems to resolve a lot better in the "as built" configuration.
> 
> Originally, I wanted the power switched when selected, but, this implementation is a lot cleaner.


 
   
  Yes - it looks good!  Bet it sounds good, too!


----------



## jdkJake

Quote: 





tomb said:


> Yes - it looks good!  Bet it sounds good, too!


 

 Yes it does. A sonic bargain at twice the price.
   
  Can't wait to see how colbaltmute follows it up...


----------



## the_equalizer

Quote: 





jdkjake said:


> Yes it does. A sonic bargain at twice the price.
> 
> Can't wait to see how colbaltmute follows it up...


 
   
  A balanced GrubDAC maybe?   
	

	
	
		
		

		
		
	


	




  I'd more than gladly build one of those, indeed.


----------



## luvdunhill

eek, forgot to take pics before I stuck it in the case... anyways:


----------



## tomb

Nice work, Marc!!  You actually drilled those holes for the cables instead of slotting them - very nice!  Those pins on the IC's look like they were wave-soldered, too!


----------



## cobaltmute

Very clean work, luvdunhill.  Deft touch with the iron and the solder.
   
  I've got a few ideas bouncing around for my next DAC...
   
   
  And for those that care about these things, it was one year ago today that I drew the first schematic for the grubDAC.


----------



## luvdunhill

Thanks guys!
   
  With the small USB connector, casing is always a challenge. Perhaps you guys could consider a stacked plexi case, similar to this:


----------



## cobaltmute

That case is cool, but how do you get the output wires off cleanly? As well, the filter caps would have an issue fitting.
   
  I'd like to see that case larger to actually see how they did it though.


----------



## limpidglitch

Quote: 





cobaltmute said:


> I've got a few ideas bouncing around for my next DAC...
> 
> 
> And for those that care about these things, it was one year ago today that I drew the first schematic for the grubDAC.


 

 Hurray, hurray!
   
  Happy anniversary!


----------



## luvdunhill

it's just stacked plexi. The inner layer is mostly missing to accomodate the board. Vertical mount RCA jacks generally suck and if you wanted to do something like the above, perhaps try RCA chassis jacks that actually thread through the PCB itself, like the old Benz PP-1 (sorry, small image again):
   

   
  Anyways, just an idea... I think the above sort of "casing" would result in the smallest, cheapest form factor possible.
   
  Quote: 





cobaltmute said:


> That case is cool, but how do you get the output wires off cleanly? As well, the filter caps would have an issue fitting.
> 
> I'd like to see that case larger to actually see how they did it though.


----------



## jdkJake

Quote: 





cobaltmute said:


> And for those that care about these things, it was one year ago today that I drew the first schematic for the grubDAC.


 

 I picked up the Beatles remasters when they came out.
   
  I just played "Birthday" from the White Album through the GrubDac in honor of the occasion.  
   
  Very nice indeed.


----------



## tomb

Quote: 





luvdunhill said:


> it's just stacked plexi. The inner layer is mostly missing to accomodate the board. Vertical mount RCA jacks generally suck and if you wanted to do something like the above, perhaps try RCA chassis jacks that actually thread through the PCB itself, like the old Benz PP-1 (sorry, small image again):
> 
> 
> 
> Anyways, just an idea... I think the above sort of "casing" would result in the smallest, cheapest form factor possible.


 


 "Smallest, cheapest form factor possible?"  Hmm ... you guys would be shocked to see what cobaltmute has up his sleeve ...


----------



## cobaltmute

Quote: 





luvdunhill said:


> Anyways, just an idea... I think the above sort of "casing" would result in the smallest, cheapest form factor possible.


 
  I don't think that by the time that you get the plexi and then get it cut to fit, that you'll be saving much over the price of the Hammond Case.  And don't forget that the form factor of the grub is also setup to have it fit into a Hammond 1455C, as well as into the MilletMAX. 
   
  Great ideas for future projects, but not in scope for the grub and its intended design points.


----------



## cobaltmute

Quote: 





jdkjake said:


> I picked up the Beatles remasters when they came out.
> 
> I just played "Birthday" from the White Album through the GrubDac in honor of the occasion.
> 
> Very nice indeed.


 

 Mono or Stereo remaster?
   
  The Mono remasters are fantastic and of the listening I've done are the better of the two.


----------



## the_equalizer

Quote: 





cobaltmute said:


> Very clean work, luvdunhill.  Deft touch with the iron and the solder.
> 
> I've got a few ideas bouncing around for my next DAC...
> 
> ...


 

  
  Nice!  Less than a year between first schematic and kits. Congratulations!


----------



## jdkJake

Quote: 





cobaltmute said:


> Mono or Stereo remaster?
> 
> The Mono remasters are fantastic and of the listening I've done are the better of the two.


 
   
  This was the stereo version. I have not ripped the mono set yet.
   
  I have yet to listen to the mono set with headphones, only speakers. They sound excellent over speakers.


----------



## barsk

Yes! Another cableGrubDAC has seen the light!
   
  And No... 
	

	
	
		
		

		
		
	


	




 Unfortunately I have bridged it somewhere and it deos not work... This is my first SMD project and a pretty daunting task at it turned out. Actually I found it quite easy to position and anchor the ICs, but then problem started. I tried using the methods mentioned in Tangent's and GrubDac tutorials but they somehow don't work with my Velleman iron with plated tips. The swiping motion is supposed to deliver a little solder and then it can be used to pickup excess. Well, it delivered too much, and picked up nothing. No matter how I tried I could not get the excess off unless with a desoldering wick. I actually found I think Tomb's method of putting a little solder on the tip and swipe just one or two pins at the time the best. So after a bit of grief I was able to produce fairly good looking soldering. I guess next time I'll do better from start.
   
  But I did get a bridge there anyway. I have 0 V on the 3.3 test point so there is a short to ground somewhere, I detect shorts on most of the caps, and that is expected. But how do I pinpoint the actual bridge? Do I have to desolder all parts one by one? I tried to look for bridges with a bright light and have removed those. I have tested with continuity meter to ensure each pin is free. I do have an extra board so I could test which pins are connected on the PCB. Those pins does buzz in the meter of course. So can it be a bridge under one of the caps then?
   
  I heard about not getting solder up on the X1, and that is my single last thing to test. Help guys?


----------



## tomb

Quote: 





barsk said:


> Yes! Another cableGrubDAC has seen the light!
> 
> And No...
> 
> ...


 

 There was a PCB defect on one PCB where the ground plane was shorted with the positive pad for C5.  However, I've inspected a number of the PCB's I have without finding the same defect.  AFAIK, no one else has had trouble with it, either.  Still, I suppose it might be something to check - see if you can measure 0 resistance between the positive pad on C5 (the one connected to the trace on the back of the PCB) and Ground (0V).  (Do this with the power OFF.)  If not, then there's no defect there.
   
  The first place to look if you're not getting 3.3V on the test point is the TPS regulator chip.  Check to see that there's no bridge there and that the pins all have good solder joints.  See if you can measure 3.3V with Ground anywhere along the trace with the pin closest to the "U2" silkscreen.  If none of that checks out, you may just have a blown TPS chip.
   
  Let's see what cobaltmute says, too.


----------



## cobaltmute

To verify, 5V at the input side?  Then test the 3V3 point.
   
  After that, it is all about trying to find the bridge.  Very close inspection with a magnifier and a light.  You could try to remove L3 to see if the TPS works or not as well.


----------



## barsk

Yes, 5 V is working, as well as the led. I also get some "USB acknowledgement" sound from the PC, but no devices show up.
   
  Good suggestion with the L3, I'll start there. And yesterday I inspected X1 and found no solder leaking up there to the top. .Two of the pins where connected with the top though, and it should be only one (tested with my spare x1). I guess that is due to the Vdd to ground short somewhere. Did not detect a PCB fault at C5 as mentioned either.
   
  Well, for the next grubDac to build  (I bought two) I will definitively look for shorts after every part soldered down. To find the error after completion is proving difficult...


----------



## barsk

Update!
   
  Removing L3 showed the TPS regulator was fine, and confirmed the other parts connected to it. So I investigated further...
  I obviously was incorrect in with my detection of bridges on the U1. I had not one but two bridges 
	

	
	
		
		

		
		
	


	




. Well, once identified one of them was easily cleared with a little solder wick. The other proved difficult. I tried to suck up the excess solder with a wick that stuck in betwwen the leads. It stuck there and some wick strands came off. From bad to really bad...
  I eventually got them all out with a little effort. But the bridge resisted. I finally took a needle and physically scrathed between the leads really carefully. And voila!
   
  Everything cleared up, I resoldered the pieces missing and connected the USB. Devices showed up and everything seems to be Ok!
  I did desolder the audio leads, so I could not test the audio. That will be done ASAP.
   
  Thanks for all your help!


----------



## cobaltmute

Hint for future - if the bridge is back far enough back that the wick doesn't seem to get it, try adding more solder to the bridge before you wick it. 
   
  Good to here that your had some success.


----------



## barsk

Thanks for the advice on the wick. I'll use it for the future for sure. There is no way to learn as much about soldering and stuff than actually doing it and learn from your mistakes. Experiance is hard earned!
   
  One reason for my troubles with that big IC chip was that I somehow got it's placement just a little skewed. I am pretty sure I had i right when I anchored it down, but perhaps I started soldering to close to the anchor point and it moved a little. So some of the pins got really close to the neighbour pad in one of the corners of the chip. Well, all sorted now and all working. Audio as well!  Sounds nice!
   
  One question about the "audiophile" quality of the cabling. What was the reasoning behind using standard hookup wire with heat shrink tubes without shielding instead of some ordinary high quality audio cables with shielding? Has anybody tried alternative cabling? Will it affect sound quality in any way to use alternatives?


----------



## tomb

Quote: 





barsk said:


> Thanks for the advice on the wick. I'll use it for the future for sure. There is no way to learn as much about soldering and stuff than actually doing it and learn from your mistakes. Experiance is hard earned!
> 
> One reason for my troubles with that big IC chip was that I somehow got it's placement just a little skewed. I am pretty sure I had i right when I anchored it down, but perhaps I started soldering to close to the anchor point and it moved a little. So some of the pins got really close to the neighbour pad in one of the corners of the chip. Well, all sorted now and all working. Audio as well!  Sounds nice!


 
  Actually, it's pretty easy to bend a single anchor pin enough to skew the chip - just as you say.  That's one reason we show anchoring pins on opposite corners, then starting the soldering on the sides that don't include those pins, as in Steps 1 and 2 shown here:
http://www.diyforums.org/GrubDAC/GrubDACstep1.php
   
  Quote: 





> One question about the "audiophile" quality of the cabling. What was the reasoning behind using standard hookup wire with heat shrink tubes without shielding instead of some ordinary high quality audio cables with shielding? Has anybody tried alternative cabling? Will it affect sound quality in any way to use alternatives?


 

 '"audiophile" quality of the cabling" ?  Just that phrase alone is enough to cause a battle around here.
	

	
	
		
		

		
			





  Certainly, there's nothing wrong with using shielded cables, but with the lengths we're using and the proximity to the PCB and components themselves, any shielding is going to have negligible impact.  Besides, the *22-ga silver-plated copper with teflon insulation* supplied in the Beezar kits is anything but "standard hookup wire" and measurably better than the wire in most any shielded cable one could purchase, except for those that are exorbitantly expensive.  It's far and away easier to solder as well, which is just as much of a goal as the sound quality obtained with SPC 22-ga wire.


----------



## barsk

Ah, I did use two anchor points. That was the point of my point 
	

	
	
		
		

		
		
	


	



  And still I messed it up!  Experiance point. I probably was too tired, doing this to late at night.
  And most parts on the GrubDaC are easy to desolder. Not that square IC...
   
  About "audiophile". Well, I did not mean to imply any critiscism on the part selection on your behalf. Only to know the reasoning behind it and wether alternatives would be of any advantage... I am well aware of that the cables are short, and most every hookup wire inside a larger case would be longer than these... The shorter the cable, the less they impact. Anyway, always on the hunt for these little improvements...




  And yes, I am using the Bezaar cableDAC kit. And followed all instructions to the letter!
   
  Btw, I looked at Bezaar about the kit and saw "teflon SPC". I should have checked what SPC stands for. (Silver Plated Copper). Sorry.


----------



## tomb

No foul - just clarifying some of the things you asked about.


----------



## barsk

Some pics of the completed build. Just a little much solder on some parts, and that U1 chip that mysteriously ended up a bit off center and causing all those problems. One can see the scratch marks near the bevel where I physically cleared that remaining bridge. There was not that many microns separating the pins from touching the neighbouring pads... The U2 chip was perfectly centered and thus very much easier to solder nicely. Also put the led in a centered hovering position illuminating the case nicely.
  Obviously also touched one Wima cap with the iron, but no ill effects from it.
   



   
  Completed!


----------



## 129207

how does it sound?


----------



## tomb

Quote: 





barsk said:


> Some pics of the completed build. Just a little much solder on some parts, and that U1 chip that mysteriously ended up a bit off center and causing all those problems. One can see the scratch marks near the bevel where I physically cleared that remaining bridge. There was not that many microns separating the pins from touching the neighbouring pads... The U2 chip was perfectly centered and thus very much easier to solder nicely. Also put the led in a centered hovering position illuminating the case nicely.
> Obviously also touched one Wima cap with the iron, but no ill effects from it.
> 
> 
> ...


 

 Nice job - great pics, too!  Ha - I can't count the number of times I've melted the corner of a Wima cap (on Millett Hybrids/MAXes/MiniMAXes/StarvingStudents).  They seem to do just fine in spite of it.


----------



## barsk

Another success story. I just built my second grubDAC, to be mated with a Pimeta which is next-in-line on my projects. Although I just got my eyes on the Minimax. Love!
  I might just end up with a miniMax real soon.
   
  This one was a breeze to finish. No problems whatsoever this time around. The blue led in the pic will be mounted on case , so it is just soldered in temporarily.


----------



## barsk

About the minimax kit.
  Is it possible to buy the complete kit without DMM and walwart? DMM I have and the walwart is the wrong voltage, we have 230 V AC here...
  Otherwise the complete kit is perfect.
   
  Sorry OT I know...


----------



## tomb

Quote: 





barsk said:


> About the minimax kit.
> Is it possible to buy the complete kit without DMM and walwart? DMM I have and the walwart is the wrong voltage, we have 230 V AC here...
> Otherwise the complete kit is perfect.
> 
> Sorry OT I know...


 
  YGPM


----------



## barsk

Quote: 





negakinu said:


> how does it sound?


 

 It sounds great!
   
  Actually it took a few hours of burn-in to loosen up. I might have been my old Sennheiser HD570's also that needed some excercise.
  I get a full, varm sound with a well defined bottom and lots of punch. This was the part that needed burn-in. Initially the bass was too dominant, but as time goes the whole sound becomes more and more balanced. The highs are well stretched out and well defined although a little harsh (see opamp below). What I miss is maybe a little in soundstage and transparency. (But I did not have that with my old setup either, using an Audigy 1 sound card).
  But this may well be because of the simple CMoy amp that I have right now . It has a OPA 2132 opamp so it is nowhere near the "audiophile" range of opamps, or headamps in general.
  (Although I power it with 24 V from a TREAD power supply,and it has a TLE 2426 virtual ground + 1880 uF caps in total so it is a fairly modified CMoy).
  The Pimeta that is next to be built and the miniMAX kit which I has just decided to buy will be much better to actually show the real capabilies of this gem.
   
  There might be a problem with my first grubDAC also. I might have put just a litte to much heat into the Wima caps when I soldered them dowm, taking Tomb's instructions of the importande of "wicking" solder all the way up to the other side of the board a little to litterately. One can see from the pics above that the wima caps are a little sideways. This may be because I suspect they have melted slightly... 
	

	
	
		
		

		
		
	


	



  I am not sure this is an issue or not. And I will be able to test how my second grubDAC sounds soon if there is any difference. There probably is not, but I thought I should mention it anyways.
   
  All that said. I am enjoying every minute of listening with this combination as it is. The sound is great and I can listen for hours on end without any fatigue. I am very happy with this part and impressed with how one can get that kind of audio quality out of such a "simple" design. Easy to build, and great support here if problems should arise!
   
  UPDATE!
  I have now been listening to my second grubDAC, the one that had no issues whilst building. And, it sounds clearly better... The mids and highs are better defined and that lack of transparency is gone. This DAC is simply the best sounding DAC this guy has ever owned. Period.
  I guess I have to seek out what is wrong with the other one. Guess I need some help again...


----------



## gurusan

Nice work barsk.
   
   
  Anyway I just got something in the mail. Thanks TomB for the fast shipping.  Just waiting on my soldering iron now 
	

	
	
		
		

		
		
	


	




 
   
  Here's the PCB next to the older prototype. The tealish color is beautiful


----------



## tomb

Quote: 





gurusan said:


> Nice work barsk.
> 
> 
> Anyway I just got something in the mail. Thanks TomB for the fast shipping.  Just waiting on my soldering iron now
> ...


 

 Nice photo!
   
  Yes, some people knock Imagineering ... Chinese PCB production, sometimes higher price, etc., but I think they do a great job.  It's all AMB has ever used, for instance - at least for production.  As you can see, though, prototype PCBs are different.  Imagineering is not very economical for small volume PCB's, so many of us use much more economical methods until we have the assurance that it takes to invest several $hundred or more into a true commercial-quality production run.  That looks like one of the proto boards that Cobaltmute had made, but that I sold at Beezar.  The reason I say that is that I tried to sand the fiberglass strands and smooth up the sides on each PCB prior to shipment. This was because the prototype PCB's were combined on larger boards that were scored on the borders of the smaller PCB's.  This is a common technique to save money on prototypes, but it sometimes leaves some rough edges when you go to break them apart (sometimes it takes actual sawing).  Anyway, sanding the edges also meant that I inadvertently sort of "rounded the corners" around the mounting holes.


----------



## Spacehead

I have completed my first Grubdac. It was very easy job. I soldered ICs pin by pin. Sound is very fluid and bright, flowing like spring water.
   



   



   



   
   
  My problem is the volume. I get insanely loud volumes from Windows default settings. I need to take the volume sliders all the way down. That means that I don't have much control of it. My comfortable volume is right in the lowest point of volume control. When adjusted further down sound stops and it is quiet.
   
  So do I have to install a volume potentiometer to my PPA v2 or is there possiblity with software to set the dac output level?


----------



## cobaltmute

If you do not have a volume pot on your PPAv2, you will need to add one.  The grubDAC will output 2Vrms full scale and then you are adding gain with your PPAv2 to increase the volume.


----------



## Spacehead

I have just completed my second GrubDac. I was too confident on my skills and didn't pay enough attention to the detail, so that this time I got some problems. It was solved in couple hours when I finally cleared the bridges on PCM2706. They were quite difficult to find.
   
  Very nice product this is! So handy, cool looks and very beautiful sound.


----------



## tomb

Quote: 





spacehead said:


> I have just completed my second GrubDac. I was too confident on my skills and didn't pay enough attention to the detail, so that this time I got some problems. It was solved in couple hours when I finally cleared the bridges on PCM2706. They were quite difficult to find.
> 
> Very nice product this is! So handy, cool looks and very beautiful sound.


 

 Great to hear it!  Once again, kudos to Cobaltmute for an excellent design and nifty package!


----------



## Lil' Knight

I've just finished populating the Grub but after plugging in the laptop, LED doesn't turn on and there's a Not recognized device message. Voltage across 0v and 5v reads only 2.45v. What could be the culprit here?


----------



## tomb

Quote: 





lil' knight said:


> I've just finished populating the Grub but after plugging in the laptop, LED doesn't turn on and there's a Not recognized device message. Voltage across 0v and 5v reads only 2.45v. What could be the culprit here?


 
  Well hopefully, cobaltmute will see this.  Meanwhile, I'd guess that something is shorted and drawing the voltage down - most likely a bridged pin somewhere?  Otherwise, there's nothing that would reduce the 5V voltage - it pretty much takes that right off the USB connection.
   
  Pics always help, too.  There's always the chance that someone else may see something you or me don't.


----------



## particleman14

start with getting that led to light up.   if you're getting only 2.45V at the 5v pad then try a different usb port.  the 5v pad is directly linked to the usb 5v power; so if ur usb is up to spec, it should be around 5V at the test pad.  swap usb ports and try dif computers if you can..
  if dac isn't being recognized by windows ,its gotta be the pcm2706/7.  put a ton of flux on it and reflow all the joints..  you'll know its good when windows auto recognizes it.
  If the led isn't lighting up check the joints on ur led resistor(r5) and check ur L1 for good connection.  maybe fixing ur 5V problem will fix the rest of the dac.  does your 3.3V test point checkout?


----------



## Lil' Knight

3.3v test point only reads ~0.49v. I tried all the USB ports on my laptop and used another laptop but the readings are still unchanged.


----------



## particleman14

if that's the case then I'm with TomB that there might be a bridge somewhere.  but it is really odd that you can't get the 5V point working. are u putting your black test probe on the OG pads when measuring voltage? 
  get that 5V test point working 1st..  perhaps test your usb cable to make sure its giving 5V.  we gotta eliminate the variables..


----------



## cobaltmute

If you don't have 5V between the 5V and 0V point, you have some sort of bridge before U2.
   
  Remove L1 and see what you get for voltages.
   
  Also look at the board from behind with a bright light and check for any bridging around L1, C5, etc.


----------



## Lil' Knight

Reflowed the L1 and PCM did the trick. Great sound coming from the Carrie.
   
  .


----------



## the_equalizer

Sweet looking combo you have there. Congratulations!


----------



## BobSaysHi

Howdy folks, I have a problem.
   
  Windows 7 recognizes my device and installs the drivers, but the led doesn't turn on. Also, more importantly, no sound.
   
  I'm going to read through the thread and see if my problem has popped up before.
   
  Ground to 5v - I get 5v
  Ground to 3.3v - I get 3.3v


----------



## Spacehead

I am trying to figure out how to correctly connect GrubDAC to PPA v2 so that I have switchable input between USB and RCA. I connect GrubDAC output ground to PPA v2 input ground and RCA ground to PPA v2 input ground.
   
  Then I connect RCA left and right to switch and GrubDAC left and right to. Switch output comes from the middle. Everything works correctly, but  when I have GrubDAC on (USB in computer) and switch selects RCA inputs, then I have *noise*.
  There is no noise when GrubDAC is disconnected from USB port.
  Then there is also no noise when GrubDAC is on and it is selected.

 This is minor problem, but I wish to have noise free amplifier that works correctly with that switch. It might get annoying to always disconnect the GrubDAC.


----------



## tomb

Quote: 





bobsayshi said:


> Howdy folks, I have a problem.
> 
> Windows 7 recognizes my device and installs the drivers, but the led doesn't turn on. Also, more importantly, no sound.
> 
> ...


 

 If you get the proper voltages, my guess is that the LED is turned backwards.  Assuming you soldered the R5 resistors properly, there's no way that the LED wouldn't light unless it's bad - if you were getting the 5V.  Remember that the "C" on the PCB stands for the cathode, which is the shorter lead on the LED.
   
  You might try checking the output connections for the problem of no sound.  Look to see if there are any bridges, or leads that are not soldered completely.


----------



## tomb

Quote: 





spacehead said:


> I am trying to figure out how to correctly connect GrubDAC to PPA v2 so that I have switchable input between USB and RCA. I connect GrubDAC output ground to PPA v2 input ground and RCA ground to PPA v2 input ground.
> 
> Then I connect RCA left and right to switch and GrubDAC left and right to. Switch output comes from the middle. Everything works correctly, but  when I have GrubDAC on (USB in computer) and switch selects RCA inputs, then I have *noise*.
> There is no noise when GrubDAC is disconnected from USB port.
> ...


 

 I've been having more trouble with the dang editor used in this new forum software.  I had an entire reply typed out, hit submit, and my reply came back blank, save for including the quote above.
   
  Whoa - this post got really messed up!!
   
  Let me try again: the contacts on the switch form a capacitive coupling that allows the sound to bleed through.  The DAC is way too sensitive and picks up the noise.  You need to use some sort of relay system as we did on the MOSFET-MAX (or MAX v1.2).  Even then, it may take two relays.  Cetoole and I experimented with using only one relay at first, but there was bleed-through on the single relay, too.  I believe the contacts on that relay (same one as the relay-delay circuit) were only rated for 55dB.  We hope that our amps have a SN Ratio of over 100dB, so you can see that it's very easy for the amp to pick up the crosstalk.  We finally settled on two relays and that seems to work for almost every case.
   
  Sorry I couldn't provide a more positive answer.  I think a DPDT switch is fine if you're just switching a couple of line-level sources, but using the DAC as one of the sources complicates things.


----------



## BobSaysHi

Quote: 





tomb said:


> If you get the proper voltages, my guess is that the LED is turned backwards.  Assuming you soldered the R5 resistors properly, there's no way that the LED wouldn't light unless it's bad - if you were getting the 5V.  Remember that the "C" on the PCB stands for the cathode, which is the shorter lead on the LED.


 

  
  Dang, you got me. The led was turned backwards. 
	

	
	
		
		

		
			




   
  Turns out that after my initial check, the audio started after clearing a short. Also, this thing sounds awesome!
   
  Thanks tomb. 
	

	
	
		
		

		
		
	


	



   
  EDIT: Also, tomb, I'm going to be building a mofsett max soon, so get ready for that.


----------



## jdkJake

Quote: 





bobsayshi said:


> EDIT: Also, tomb, I'm going to be building a mofsett max soon, so get ready for that.


 

 Oh, oh. Run for the hills Tom, run for the hills!


----------



## BobSaysHi

Hey guys, I have a problem.
   
  When playing audio through my grub, it occasionally pauses, as in the audio stops for a split second, then continues. I've tried everything I can think of on both the software side and hardware side, but I am obviously missing something. 
   
  Any ideas? The only thing I haven't tried yet is reflowing the two chips. Could I have damaged anything on my board?
   
  My computer is probably up to snuff, and latency isn't an issue.
   
  Quad core @ 3.20ghz
  4gb of RAM 
  Windows 7
   
  I have asio4all up and running in foobar.
   
  Any ideas?
   
  (I am checking my Minimax now to see if the issue is there)


----------



## cobaltmute

Try the WASAPI plugin for foobar.  I've had good success with it under Windows 7.


----------



## Avro_Arrow

Ya, I recommend WASAPI as well...I use it with Foobar under windows for both of my DACs.
  
  Quote: 





cobaltmute said:


> Try the WASAPI plugin for foobar.  I've had good success with it under Windows 7.


----------



## BobSaysHi

gotcha, I'll try that in a little while.


----------



## BobSaysHi

Success! I'll have to test it for a little while to make sure the pops don't come back, but that seems to have done the trick.
   
  Thanks a lot guys.
   
  EDIT: yup, no skips, everything's good


----------



## Avro_Arrow

Good Job Bob!


----------



## tomb

Quote: 





bobsayshi said:


> Success! I'll have to test it for a little while to make sure the pops don't come back, but that seems to have done the trick.
> 
> Thanks a lot guys.
> 
> EDIT: yup, no skips, everything's good


 

 Ditto, BobSaysHi!
   
  That's a great achievement after your first experience with the MiniMAX!


----------



## ovrclkd

Quote: 





bobsayshi said:


> Quote:
> 
> 
> 
> ...


 
   

  Not to hi-jack but you will really enjoy the MOSFET MAX... great build ...great amp. Make another Grub for it, I piggybacked mine on the back leaving the Bantam inside and made it switchable for more options.
  Don't forget to grab different matched tubes from tomb while ordering!
   
Clickety Click


----------



## BobSaysHi

Quote: 





tomb said:


> Ditto, BobSaysHi!
> 
> That's a great achievement after your first experience with the MiniMAX!


 

 lol, I'm sorry about all the trouble. I've learned a lot since then. 
	

	
	
		
		

		
		
	


	



   


  Quote: 





ovrclkd said:


> Quote:
> 
> 
> 
> ...


 

 I'm honestly really, really happy with my setup right now. I don't think I'll attempt any upgrades for a while.


----------



## BobVA

Hi:
    I just finished building the GrubDAC and was surprised how hot the output is.  I plugged the output into my Total BitHead and it immediately began illuminating the clipping LED, which I attributed to low batteries.  After turning the house upside down for new ones (and getting side tracked looking for a nimh charger!) I figured out that wasn't it - it was being overdriven when I ran it with the computer volume at max (which I do with no problem with the BitHead when it's hooked up to the USB port and with my off-board audio interface)
   
    I'm now listening to the output of the GrubDAC directly with a pair of Denon D5000's, at about 1/4 volume.  Wow.
   
    I'm planning to use this as an input to a Millet Max - do I need to include an input level pad to keep it from being over driven?
   
  Regards,
    Bob


----------



## BobSaysHi

Quote: 





bobva said:


> Hi:
> I just finished building the GrubDAC and was surprised how hot the output is.  I plugged the output into my Total BitHead and it immediately began illuminating the clipping LED, which I attributed to low batteries.  After turning the house upside down for new ones (and getting side tracked looking for a nimh charger!) I figured out that wasn't it - it was being overdriven when I ran it with the computer volume at max (which I do with no problem with the BitHead when it's hooked up to the USB port and with my off-board audio interface)
> 
> I'm now listening to the output of the GrubDAC directly with a pair of Denon D5000's, at about 1/4 volume.  Wow.
> ...


 

 Hi Bob (get it? 
	

	
	
		
		

		
		
	


	




)
   
   
  I'm not quite sure I know what you mean when you say "overdriven," but you should be fine plugging it into Millet Max. I have mine hooked up this way, and it isn't "overdriven."


----------



## BobVA

( overdriven = driving the amplifier with an excessive input signal, resulting in clipping on the output, which is what I was seeing when I hooked the GrubDAC to the Airhead.)
   
  Good to hear that - are you running the computer "volume control" (e.g. the slider you get when clicking the speaker icon on Windows) at full?  Or is that turned down? 
   
  Appreciate the input - I don't quite have everything glued together sufficiently to actually try this with my pile of parts.
   
  Thanks!
    Bob


----------



## BobSaysHi

Quote: 





bobva said:


> ( overdriven = driving the amplifier with an excessive input signal, resulting in clipping on the output, which is what I was seeing when I hooked the GrubDAC to the Airhead.)
> 
> Good to hear that - are you running the computer "volume control" (e.g. the slider you get when clicking the speaker icon on Windows) at full?  Or is that turned down?
> 
> ...


 

 Do you not have either ASIO or WASAPI installed to bypass the system volume? if not you should keep the volume at like 50%. I'm going to let tomb or one of the other more experienced users take over, because I'm not sure of the details.


----------



## tomb

Actually, the OS's software volume on the PC should be set to full.  Otherwise, you get some digital coding errors.  Not enough to cause noticeable problems in the music, but enough that it raises distortion levels, perhaps.  I may not be stating that just correctly, but I've seen it posted by many who know a little more about it than me.  It's the same reason people go for the ASIO, although admittedly - I've never gone that far.
   
  I'm suspecting that perhaps something else is going on.  The GrubDAC is not overly strong on output, certainly on a par with the BantamDAC, AlienDAC, etc. - and that's much lower than component CD/DVD players, for instance.  Have you measured the outputs for DC offset?  There are no blocking caps on the GrubDAC, but I'm wondering if something else could be messed up that may be causing some DC offset on the output.  That might raise the top signal level to something that would cause the Airhead to clip.


----------



## BobSaysHi

Quote: 





tomb said:


> Actually, the OS's software volume on the PC should be set to full.  Otherwise, you get some digital coding errors.


 

 Wow, really? I did not know that.


----------



## barsk

What you want from the PC is bit perfect audio. That is, the bit stream from the source should not be altered in any way when going through the mixer and out in digital form to the DAC. ASIO and such which is available from dedicated media players like Foobar2000 etc have an option to play the audio with plugins that can do this properly. If you have MP3, FLAC etc and play it on the PC with a media player. Go for Foobar2000 or another with similar capabilities,
   
  But, as I  understand it, Vista and Win7 can also play "bit perfect" as long as you set the preferred output data format to CD quality, i.e 44.1 KHz, 16 bit, and set the volume to 100%. I think this is true, but I would like confirmation from others wether it really is bit perfect or if the windows mixer is somehow dithering the data anyway?
   
  What happens when you decrease the digital volume is that the mixer is altering the digital data, i.e reducing the actual information there is and then reformatting the data according to some algorithm. The best sounding data is always the unaltered one. All alterations are in some way destructive for the sound quality.
   
  So what Tomb says above that there is "coding errors" is in not entirely true. There is a controlled way to digitally decrease volume, and the result is not "error". It is a slightly decreased audio quality due to alterings of the original digital data. Most people doesn't recognise this when they listen anyway. But it is there!
   
  Of course when there is system sounds or several sound sources that needs to be mixed into the output, the pure bit perfect is lost...
   
  /Barsk


----------



## tomb

Well, if it's not "bit-perfect," then there are errors.
	

	
	
		
		

		
		
	


	




  We're saying the same thing, though.


----------



## BobSaysHi

GAH!
   
  I've made a mistake. How would you recommend desoldering U1? I put it on the wrong direction. I'm thinking that getting a solid copper cable and making a square out of it so it hits all the pins at the same time, hopefully desoldering it completely. Are there any other methods for desoldering that don't require me to run up to radioshack?


----------



## tomb

Quote: 





bobsayshi said:


> GAH!
> 
> I've made a mistake. How would you recommend desoldering U1? I put it on the wrong direction. I'm thinking that getting a solid copper cable and making a square out of it so it hits all the pins at the same time, hopefully desoldering it completely. Are there any other methods for desoldering that don't require me to run up to radioshack?


 

 Actually, your solid copper idea sounds like an interesting thing to try.  I'd be concerned that it would just solder/stick itself to the pins/PCB and you'd end up with a worse mess, though.
   
  For two-sided chips, the best method is to create a solder blob on one side.  That will let you melt all the pins at once and with a small screwdriver or knife, lift that side of the chip until it's disconnected with the pads.  Repeat for the other side.  You have to be careful not to let the chip get too hot while you're doing this, but it is a repeatable method and fairly dependable.
   
  With a four-sided chip, I think I'd do adjacent rows and see if you could lift from the corner.  Once you got a corner up, you could progress patiently to another corner.  Just a guess, I haven't actually had the experience of trying it on a square chip, yet ...


----------



## BobSaysHi

Quote: 





tomb said:


> Quote:
> 
> 
> 
> ...


 

 Success! I guess I should have held my tongue and gone ahead and tried it 
	

	
	
		
		

		
		
	


	




. It's kind of embarassing since this is the 7th (
	

	
	
		
		

		
		
	


	




) grub I've built, and besides the first one, they all worked without any serious problems.
   
  In case anyone else has this problem, here's what I did. I stripped down a 22ish gauge solid wire and cut it so that the wire would bend and cover two sides of the chip's pins. Same for the other two sides. I flooded all the sides with solder to hold the wire in place. Then I heated the wire on the corner so that the heat would travel evenly two two sides, then I alternated between the sides until it heated up enough that the chip was loose. Make sure to use a lot of flux.
   
  On a unrelated note, Uncle Erik gave me MOT status over some off remark I said in the Members Lounge about building DIY stuff for other members. I'm not really sure how I feel about that, especially since I screwed up so royally on my Minimax build. Hopefully I'll redeem myself on my Mofset Max (that I almost have enough money for 
	

	
	
		
		

		
		
	


	




)


----------



## tomb

If he gave you MOT status based on conjecture, that's quite a trip-wire on his part.  Heck, I begged for over a year for Jude to give me MOT status - well after I started Beezar.
   
  Why don't you send him a PM and explain?  It's quite a step from talking about long-term goals vs. becoming MisterX overnight.  He should cut you some slack.
   
   
  P.S. Glad to hear you got the chip removed!


----------



## BobVA

Quote: 





tomb said:


> Actually, the OS's software volume on the PC should be set to full.  Otherwise, you get some digital coding errors.  Not enough to cause noticeable problems in the music, but enough that it raises distortion levels, perhaps.  I may not be stating that just correctly, but I've seen it posted by many who know a little more about it than me.  It's the same reason people go for the ASIO, although admittedly - I've never gone that far.
> 
> I'm suspecting that perhaps something else is going on.  The GrubDAC is not overly strong on output, certainly on a par with the BantamDAC, AlienDAC, etc. - and that's much lower than component CD/DVD players, for instance.  Have you measured the outputs for DC offset?  There are no blocking caps on the GrubDAC, but I'm wondering if something else could be messed up that may be causing some DC offset on the output.  That might raise the top signal level to something that would cause the Airhead to clip.


 

  
  Hi Tom:
    Using a software "signal generator" on the PC set at 0db, and with the PC output set at maximum, I'm getting a tad below 3v p-p on the output channels with both a sine wave and white noise.  DC coupled scope showed nothing when I turn off the input signal.  Voltmeter was under 1 mV on each channel (and that was probably noise), so no DC offset I can see.  I fed the output into a little table radio I've got on the bench as a test amp and it also distorts when I get the digital output level above about 75%.
   
    That said, the signal looks very, very clean on the scope even wide open, and it sounds great, so I don't think anything is malfunctioning.  Just running a lot hotter than the specs. ( Vdd is 3.31VDC, too.) 
   
    So, I'll pad it down to 1.5 volts or so and I think that will work out. 
   
    On the topic of lowering the "digital" volume control not being desirable I believe your observations are spot on.
   
     When the "volume" is decreased what the PC does it multiply the digital data by a scaling constant from 0 to 1.  1 = 100% volume, 0=muted.    The simplest way to think about it is if you reduce the volume to 50% - the effect of that is to mask off the high order bit on the 16-bit data words that carry the audio information. [Edit - for data words that had the high order bit  set in the first place - smaller values would be similarly scaled.  Just masking off the high order bit actually the equivalent of hard limiting the signal...but stick with me!]   So instead of varying from 0 to 2^16 ( 0 to 65,535)  they would then only go to 2^15 (32,768), cutting the [peak] volume in half. 
    The problem that presents is that the input (from the CD or whatever) is still generating 16 bit samples which the scaler is now compressing  into 15 bits, effectively "throwing away" one bit of data, which translates to 32,768 values it can't generate on the output. 
     Now imagine you turn the digital volume WAY down, masking off all but the lower four bits.  The entire signal is still in there, but now it can only vary over 16 levels of volume.  That's not going to sound very good at all! 
     With the more realistic 15 bit example exactly the same thing is happening, just not as drastically.   You're only getting 15 bits of data where you could have 16
     Technically this increases "quantization noise", which are the artifacts generated by reproducing a signal that can have infinitely many values with a device that can only generate a fixed number of values. 
   
     Now, if instead you pad down the output of the DAC using an analog technique (potentiometer, negative gain stage, etc) then entire 16-bit range of values will still be present in the lower volume output, it's just that the size of the step between adjacent values has been reduced.  If you pad the signal down by 25 dB in the analog domain you can still get the original signal back, with all the steps, by just amplifying it by 25 dB, unlike the digital example above.  (Of course there are practical limits to this due to amplifier noise, etc.)
   
    Yikes - sorry!  Hope I didn't bore anybody to death   Fun to talk about, though!
   
  Regards,
    Bob
  PS Thanks for the tip on the Hako soldering station and SMT soldering you gave me at CanJam 2010! Worked great on the GrubDAC.
   
  [Edited - I oversimplified the scaling vs. masking discussion, so comments in brackets added to clarify]


----------



## barsk

@BobVA: Great tech summary of what´s digital volume does!


----------



## cobaltmute

Quote: 





bobva said:


> Hi Tom:    Using a software "signal generator" on the PC set at 0db, and with the PC output set at maximum, I'm getting a tad below 3v p-p on the output channels with both a sine wave and white noise.  DC coupled scope showed nothing when I turn off the input signal.  Voltmeter was under 1 mV on each channel (and that was probably noise), so no DC offset I can see.  I fed the output into a little table radio I've got on the bench as a test amp and it also distorts when I get the digital output level above about 75%.
> 
> That said, the signal looks very, very clean on the scope even wide open, and it sounds great, so I don't think anything is malfunctioning.  Just running a lot hotter than the specs. ( Vdd is 3.31VDC, too.)


 
   
  Spec on the output is 2.1Vrms typical and up to 2.31Vrms max, so if my math is correct, you are still within spec as that is up to 3.26Vp-p.  DC offset is spec at 1mV max so you are in spec on that as well.


----------



## BobVA

Quote: 





cobaltmute said:


> Quote:
> 
> 
> 
> ...


 

 @cobaltmute: Thank you!  I'd had "two volts" in my head from somewhere, and I just assumed p-p.   Should have looked at the spec sheet.
   
  I got a couple of 15 turn pots today, so I'll see how padding it down works, just for fun.  I just realized that it's probably a moot point with the Millet Max: it's fixed gain with a variable attenuation on the front end, so if I would have just hooked the DAC to it I'd probably never noticed a problem (as BobSaysHi noted).
   
  But I'm thinking about bringing the output of the DAC out to a jack on the back of the headphone amp I'm building, then patching back into an input, so I can use the DAC as a standalone item if I need to.  Getting the level down a bit might still be a good idea.
   
  @Barsk: Glad you found it useful!
   
  Regards,
     Bob


----------



## BobSaysHi

Hi guys, I have a semi-related problem that is troubling me. Every time I turn on my lamp that is on the same power strip as my computer my DAC stops working (it freezes or something). Would buying a better power strip fix this? I have a generic "Staples" brand power strip.


----------



## nullstring

Quote: 





bobsayshi said:


> Hi guys, I have a semi-related problem that is troubling me. Every time I turn on my lamp that is on the same power strip as my computer my DAC stops working (it freezes or something). Would buying a better power strip fix this? I have a generic "Staples" brand power strip.


 
   
  Have you tried moving the lamp off of the power strip (but still on the same circuit) and seeing if it fixes it?
   
  If thats the case, I would suppose a better power strip would fix it. (but that'd be pretty weird)


----------



## Avro_Arrow

Try putting one of those snap on transient suppressors on the USB cable.
  You could aslo try one on the lamp cord.


----------



## cobaltmute

I have seen the same kind of issue with a different DAC I built.  Turning the amp off would shut the DAC down, but it is not a reliable occourance so it makes it difficult to determine what exactly is happening.  I'm wondering if it is a ground bounce or something similar.


----------



## BobSaysHi

Oops. I could have sworn I replied to this thread yesterday.
   
  Quote: 





nullstring said:


> Quote:
> 
> 
> 
> ...


 

 I just looked, and the lamp isn't on the same power strip. I have two strips plugged into the wall. One strip has my computer, amp and telephone. The other has my monitor, soldering iron (it's home is on my desk), my cell phone charger, and my lamp.
   
  Also, the DAC only stops when I turn the lamp off, not on, like I said earlier.


----------



## ShinyFalcon

Likely magnetic/radio interference. My GrubDAC freezes when my UPS activates due to mains fluctuation. Also happens if there's some intense lightning. My lamp has the twist switch, maybe that's more gentler compared to the rocker type.


----------



## BobVA

Quote: 





bobsayshi said:


> Oops. I could have sworn I replied to this thread yesterday
> 
> I just looked, and the lamp isn't on the same power strip. I have two strips plugged into the wall. One strip has my computer, amp and telephone. The other has my monitor, soldering iron (it's home is on my desk), my cell phone charger, and my lamp.
> 
> Also, the DAC only stops when I turn the lamp off, not on, like I said earlier.


 
   
    I'm guessing it's an inductive spike being coupled into either the audio or USB cable.  Try unhooking the audio cable, switching off the lamp, then plugging the audio cable back in.   If it's still working then it's the audio cable. If not, I'd suspect the USB cable.  (It may also be a power-line spike coming from the ballast in the lamp (florescent?) getting into the audio cable via the audio gear is connected to it.)
    I'd be surprised if a power line spike was making it through the PC power supply and the DAC power supply chip.  Is the computer a laptop?  If so have you tried to see if the problem occurs on battery power?
   
     If it looks like the USB or audio cable try a snap on choke, as Avro suggested.  For best results use the open core type (looks like an open rectangle for the snap on style or just a circle for the pull-through types) that you wind several turns of the cable through vs. the ones that just snap around the outside of the cable.  (Follow the directions on the package exactly for winding the cable - the direction of the turns is important if you wind on both sides of the rectangular types.)
  
  Good hunting!
    Bob


----------



## BobVA

Quote: 





bobva said:


> But I'm thinking about bringing the output of the DAC out to a jack on the back of the headphone amp I'm building, then patching back into an input, so I can use the DAC as a standalone item if I need to.  Getting the level down a bit might still be a good idea.
> 
> 
> Regards,
> Bob


 

 That worked out pretty well.  I used 1k / 15 turn pots on the output channels.  After fiddling with them for a bit (0 db?  +4 db?) I just punted - I connected the line out of my iPod to an analog input of my (just finished!) amp and my computer to the USB/DAC input, both playing the same song. Then I adjusted the DAC output pads until I couldn't tell any significant volume difference between the two, and then equalized the two DAC channels with the scope.
   
  GrubDAC -> Millet Max -> RS2 or D5000 sounds great.  Millet also does a fantastic job with my hard-to-drive Senn HD-580's


----------



## csholtmeier

I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
   
  Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
   
  Bad U1 maybe?


----------



## jdkJake

Do you have access to a multimeter to make some measurements?

A picture with as much light and focus as you can muster of the top and bottom of the board would also be helpful.


----------



## tomb

Quote: 





csholtmeier said:


> I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
> 
> Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
> 
> Bad U1 maybe?


 

 I apologize for not activating your account - it's done now.  Because of previous abuse, I run a "whois" on the IP address of an account request.  If the "whois" gets blocked (yours did) or if the trace log bounces to some domains that I know are abusive, I do not activate the account.  While a blocked whois is not necessarily a spam indication by itself, the uncertainty was enough to make me suspicious without additional info.  Again, my apologies.
  As for your GrubDAC - what jdkJake said.


----------



## cobaltmute

Quote: 





csholtmeier said:


> I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
> 
> Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
> 
> Bad U1 maybe?


 

 Is your board clean?  And as the others said, you can check the 3V3 point for voltage when the board stops working.


----------



## Eyediver

Cobaltmute,
  Would you be willing to take a look at my posting about a GrubDac at a different location when convenient?
http://www.head-fi.org/forum/thread/531688/grubdac-assistance-please
   
  I would much appreciate your expertise.  Thanks.


----------



## csholtmeier

Sorry it took so long to get these, my plate has been a little full lately.
   
  Board looks clean to me, and like I said, reflowing U1 gets me a short amount of operation.


----------



## jdkJake

Have you verified 3.3VDC at the test point?

There is still quite a bit of flux on the board, particularly the bottom. Suggest you use 91% alcohol (available at any drug store) and a nylon toothbrush to scrub it off.


----------



## csholtmeier

3.278 at test point. Leftover flux is from reflowing. I've cleaned the board with alcohol and a toothbrush.


----------



## BobSaysHi

Quote: 





csholtmeier said:


> 3.278 at test point. Leftover flux is from reflowing. I've cleaned the board with alcohol and a toothbrush.


 

 Might be a software problem. Are you using WASAPI? My problems went away after using it. Have you tried it on another computer?


----------



## csholtmeier

On OSX- VLC, ITunes, and Play. 

On W7 and XP- VLC, iTunes, windows media player.


----------



## cobaltmute

So does the DAC disconnect or just stop making sound?


----------



## csholtmeier

It shows up in control panel/audio midi, but does not produce sound.


----------



## jdkJake

So, if reflowing U1 brought it to life ( at least temporarily) and reflowing then took it out, then I suspect you still have U1 solder issues. There is most likely a small bridge between one or more sets of pins.

Do you have needle points for your multimeter? Without power applied to the board, I would test for resistance between each set of pins. Determine which sets are bridged and then compare that list against the schematic to determine if they are intended to be bridged and/or connected via the rest of the circuit. This process is slow and meticulous, but, pretty much guaranteed to help pin point the trouble area without performing endless reflows. 

There is a fair amount of solder on some of the pins. It might as simple as reducing some of that through judicious use of flux and solder braid to remove the excess. Flux one side worth of pins, place braid over them and the run your iron over the braid. This will cause the heat to draw the excess solder onto the braid while leaving plenty of solder to keep the joints sound.

BTW, did you reflow X1?

EDIT: from the pics, pins 15 and 16 look suspect. I would start there.


----------



## riceracer

hi
   
  hopefully someone can help me out, or at least give me a bit of direction. Sorry I dont have a cam that can macro right now, so I dont have any pictures. Anyhow, I got a grubdac kit the other day and assembled it. First it would detect on my PC perfectly fine, but not output any audio. After reading a bit, it appeared that that would be one of the 4 lines between the pcm2706 and the wolfson chip, I checked continuity on those and found one to have high resistance, and reflowed that pin. After that, those 4 lines read fine continuitywise, and I would get audio output. However the audio sounds incorrect..im not sure how to explain it. its distorted, but not like analog distortion, or at least not that I think. it exists at all levels, both using a pot on my headphone amp, and inputting into a h&k on my test bench, as well as reducing the volume on the PC. Ive tried output via wmp, media player classic as well as foobar w/wasapi plugin, and it sounds the same. I went around to all of the 2706 and 8524 pins and checked the continuity to adjacent points and it appeared correct, so im sorta stumped on what to do, any ideas? Oh, and possibly needless to say at this point, but the led lights fine, and +5/+3.3 read fine.
   
  I will work on trying to get few pics of the board as well.
   
  rice


----------



## jdkJake

Riceracer, 

Which chip did you reflow to fix the initial problem (U1 or U3)?

Is it pure distortion or is "music" recognizable?

What is the measured voltage on U3, pin 12 (AIFMODE)?


----------



## riceracer

U1
  the music is recognizable, but like coming through almost a walkietalkie or something hideous like that.
  I will go check that voltage in a moment and get back,
   
  thanks
   
  rice


----------



## jdkJake

Interesting. Almost sounds like you do not have a ground reference or similar.
   
  I would check pins 4 and 13 as well.


----------



## riceracer

sorry for the delays, the weather is threatening in this region. I checked pin 4 and 13, continuity to ground is good. pin 12 has 3.28v in operation. does that sound right?
   
  thanks again for your help 
  
  rice


----------



## jdkJake

Quote: 





riceracer said:


> sorry for the delays, the weather is threatening in this region. I checked pin 4 and 13, continuity to ground is good. pin 12 has 3.28v in operation. does that sound right?
> 
> thanks again for your help
> 
> rice


 


  Yes, that is fine.
   
  Really strange. If you didn't buy the kit, I would suspect you might have bad values for either r8/r9 or C16/17. 
   
  How are you cabled up to J3? It still sounds like a ground problem somewhere.


----------



## riceracer

by j3 do you mean the analog output lines of the grubdac or am I missing something? right now i have them soldered to a stereo headphone jack, that goes into a headphone->rca into my receiver, before they were wired directly into my opa2132/buf634 headphone amp. I will check the continuity across all grounds and make sure it is clean, maybe there is a problem with my jack or something. I can swap this for RCA jacks as well, I just used the headphone because it was already sitting on my bench. As another point to note, and possibly should have been mentioned earlier, the miniUSB connector supplied did not fit correctly into the board, I had to cut off one of the mounting 'feet' to make it align. However the cut one was the one that does not have a grounding pad connected anyhow, so I did not think this would affect the operation. 
   
  rice


----------



## jdkJake

Yes, I mean the analog output.
   
  Since you hear music, odds are very good there is little to no problem with the digital side. Since the analog out portion of the WM8524 is so wonderfully simple, there are only a few pins that might possible effect the output. Have you checked pins 6 and 14 as well?
   
  I am confused what you mean by "headphone->rca". You do not have a headphone in line with the output do you?


----------



## riceracer

no, i mean a stereo headphone to rca adaptor, so I can plug it into the aux in on my receiver. I will go check all of the pins on the wm chip again as well as the grounds, I agree it seems like the digital side is working correctly.
   
  rice


----------



## riceracer

ok, i checked a bit more, pin 6 looks good to +3.3v point, pin 14 looks good to the side of c9, and i removed the headphone jack and soldered in two rcas, ground continuity is clean from the rcas as well, but the sound issue still persists. I thought about it a little more, and i think the best i can describe it is an FMradio that is slightly off of being tuned correctly, so you can hear the music, but you get a lot of ugliness around it as well.
   
  rice


----------



## jdkJake

riceracer said:


> ok, i checked a bit more, pin 6 looks good to +3.3v point, pin 14 looks good to the side of c9, and i removed the headphone jack and soldered in two rcas, ground continuity is clean from the rcas as well, but the sound issue still persists. I thought about it a little more, and i think the best i can describe it is an FMradio that is slightly off of being tuned correctly, so you can hear the music, but you get a lot of ugliness around it as well.






What was the value at pin 14? 

Certainly a head-scratcher....


----------



## csholtmeier

jdkjake said:


> ASo, if reflowing U1 brought it to life ( at least temporarily) and reflowing then took it out, then I suspect you still have U1 solder issues. There is most likely a small bridge between one or more sets of pins.
> 
> Do you have needle points for your multimeter? Without power applied to the board, I would test for resistance between each set of pins. Determine which sets are bridged and then compare that list against the schematic to determine if they are intended to be bridged and/or connected via the rest of the circuit. This process is slow and meticulous, but, pretty much guaranteed to help pin point the trouble area without performing endless reflows.
> 
> ...





 


I checked continuity between all pins on the U1. Everything was 1.5K ohms and higher except pins 25(zgnd), 26(agndl) and pins 2(vccp), 3(host). According to the schematic these two circuits are connected. I did not check one pin to another as per the schematic(there are other pins that are connected), only side by side pins looking for a solder bridge.

I did not reflow X1.


----------



## jdkJake

csholtmeier:
   
  When you say "or higher" do you mean open (or infinite) resistance or an actual value?
   
  Did pins 15 and 16 measure 1.5k? Pins 23 and 24 about the same (~1.5k)?
   
  So, next up is to measure each active pin to it's next component in the circuit. For example:
   
  pins 1, 9, 20, 25, 26 and 31 to Ground,
  pins 2, 3 16, 21 and 24 to VDD (3.3 test point),  
  pin 12 to (and thru) R7 to X1 (pin 3),
  pin 15 to (and thru) R6 to VDD,
  pin 17 to U3 (pin 7)
  etc...
   
  You need to verify each pin of U1 is completing it's intended circuit and matches the mapping on the schematic. 
   
  I would also do the same for U3. Verify no bridges across adjacent pins and also verify connectivity to the next element of the circuit.


----------



## asak

I have an issue with my grubdac build too. Can get the light to come on and the computer recognizes it, but no sound comes out. The 3.3 volt tests alright too. There seem to be a bridge for the TI PCM chip on one of the corners which almost seems intended from the circuit board. Any ideas to fix?


----------



## tomb

Quote: 





asak said:


> I have an issue with my grubdac build too. Can get the light to come on and the computer recognizes it, but no sound comes out. The 3.3 volt tests alright too. There seem to be a bridge for the TI PCM chip on one of the corners which almost seems intended from the circuit board. Any ideas to fix?


 

 That sounds more like an issue with the Wolfson chip.  If the computer recognizes it, that's about all the TI PCM chip is supposed to do.  Sound comes from the Wolfson - check that one.
   
  As for "bridge" on the PCB, I think some people are mistaking the releived ground plane connections for "bridges."  They look like a perpendicular trace that crosses the pins on the IC chips.  That's only to keep the full force connection of the ground plane from contacting the pads for the IC's pins.  This is an SMD technique that seems to work well.  On a through-hole PCB, you'll notice the same thing but the relieving is usually accomplished by four tiny connections to the four quadrants of the pad.  All of this is to keep you from having to heat the entire ground plane to melt the solder.


----------



## asak

TomB-
   
  Appreciate the quick help. Reflowed the Wolfson chip, and got some sounds.
   
  This thing is really good. Just using it to drive headphones, seems to have plenty of power. Definitely like how it sounds.


----------



## tomb

Quote: 





asak said:


> TomB-
> 
> Appreciate the quick help. Reflowed the Wolfson chip, and got some sounds.
> 
> This thing is really good. Just using it to drive headphones, seems to have plenty of power. Definitely like how it sounds.


 

 That's great news!  Glad to hear you're enjoying it!


----------



## riceracer

Ok, sorry i got iced over by recent storms and had to shift some priorities, anyhow i finally got to checking the voltage on pin 14, which i gather is the midpoint of the internal rail splitter, it read 1.63v so that sounds like what I would expect from a midpoint of a 3.28v rail, right? I am going to take it back to the lab in which it was originally soldered and review it again, i may reflow the wolfson chip and see if that improves the sound output. If anyone has any other ideas, please let me know
   
  thanks
   
  rice


----------



## eprst

Hello
   
  One more problem building GrubDAC here. Populated the board with mini-USB connector, no output connector yet. PC complains about excessive power draw on attempt to plug it in and shuts down the port, led doesn't light up.
  I think I've checked about everything, all the U1 and U3 pins, X1, all SMD parts for short circuits and components connectivity and now I'm out of ideas.
   
  Here're the photos. I know that C7 looks suspicios, but multimeter says it's OK. You may also notice that DOUT on U1 isn't soldered, fixed that.
   
http://dl.dropbox.com/u/3311440/_MG_4224.JPG
http://dl.dropbox.com/u/3311440/_MG_4225.JPG
  (sorry for dropbox, picture upload seems to be broken)
   
  This is my first DYI project, so I could have done a stupid mistake somewhere.


----------



## jdkJake

First off, you have J1 (the USB connector) mounted on the wrong side of the board. That is exchanging the signals into the board, most importantly power and ground.

I would fix that first.


----------



## akgfan

Grubdac looks much smaller than on pictures. Soldering is a bit tricky on parts conected with large ground pad. I soldered it with soldering gun and fine wolframe tip. Took me almost 6 hours, but looks nice. It plays differently than sound card and everything sounds different. Happy so far. 
	

	
	
		
		

		
			




   
  Edit: I'm not sure whether the tip is called wolframe actually. I can't find any information, just what I remember. However, this tip never broke.


----------



## cobaltmute

You did it with a soldering gun?  That's very good.
   
  And yes it seems smaller in real life than on the pictures.


----------



## eprst

Quote: 





jdkjake said:


> First off, you have J1 (the USB connector) mounted on the wrong side of the board.


 

 lol
  ok, fixed that, seems to be working now. thank you!


----------



## akgfan

Here are my pictures. Strange, how differently it looks than in reality. I don't bother with cleaning much. I cut small piece of tin and try to solder each part at first try. Some parts like L1-L3 refused. ICs need to be sucked, but with the right amount of tin it's possible to solder many pins without shorting them. Tough job with soldering gun, but it's possible. If you don't have soldering iron, don't worry, go for it!


----------



## cobaltmute

I do some of the development work on my 24" work monitor.  With the board taking up the whole screen.  Perspective is hard to get sometimes.


----------



## jdkJake

Wow akgfan, I cannot believe you soldered those parts with a gun vice an iron. You are far more patient and have far better eyesight than I! 

Heck of a job on those IC's. 

What are you going to mount the dac? Do you have an enclosure picked out?


----------



## akgfan

No, I don't have any enclosure yet. It just sits on my table.


----------



## akgfan

Well, I got an inspiration today. And with a bit of perspiration I made this:
   

   
  BTW I use 40cm usb2.0 cable from external hdd.


----------



## cobaltmute

Very nice.
   
  Would you mind sharing what you used for a case?  Other may be interested.


----------



## akgfan

It's a case from pins, I think. I have another case, the same, and it was from tourmalin mineral my mother bought long time ago. It is probably used for jewellery too.


----------



## akgfan

Why is output load of wolfson dac limited to 1k-47k ohm? I'm thinking of 10k input pot in my amp now because I wanted 100k, and temporarily have 47k. Can I buy 50k?


----------



## cobaltmute

Quote: 





akgfan said:


> Why is output load of wolfson dac limited to 1k-47k ohm? I'm thinking of 10k input pot in my amp now because I wanted 100k, and temporarily have 47k. Can I buy 50k?


 


  I'm not sure where you see the upper limit on the output load.  If you can refer me to that, I'll look at.
   
  The datasheet does say that you should load it with at least 1K, but I have driven headphone direct to see what it would do.


----------



## akgfan

I'm not sure if it is just because that measured maximum output voltage. But it's not very good written:


----------



## cobaltmute

You may want to check the production datasheet.  You are looking at the pre-production one.


----------



## akgfan

Oh, I wasn't aware of that. I downloaded it from some datasheet web page. So I'll buy awailable pot then.


----------



## cenotaph

*EDIT!* fixed somehow, I guess the scratch doesn't matter much.. Might have been a bad usb cable connection (green one). Anyway, I am enjoying it now 
   
Hey all, just got my grubDAC and am having some trouble with it, first the board has gotten scratched (by L2) and now two pins always ground because the solder flows into the scratch. Second, and possibly due to this, windows does not recognize the dac. Any help appreciated.
   
  Pics:


----------



## RuiCanela

Just like akgfan, I removed the initial cable with 3.5mm Neutrik plug and used a female stereo connector,some solid core silver wire insulated with Teflon (curves are for the signal paths have the same length).
  I use the regular Hammond case sold by Beezar.
  The cable was removed because with this configuration pack in a bag is easier.


----------



## eprst

Quote: 





eprst said:


> lol
> ok, fixed that, seems to be working now. thank you!


 

 Well, actually it doesn't. OS recognizes it, then after a couple of minutes it disconnects and can't be recognized again. Not an excessive voltage issue, led stays on, just usb errors. I've replaced miniUSB by pigtail USB cable, it was recognized and then after some time got disconnected again. I did nothing at all, happened all by itself. And now it seems to be permanently broken, re-plugging doesn't help.
  So far I tried different PC's and OS's (mac, win xp, linux) - same thing everywhere.
   
  Here's sucessful connection output (notice there're still a couple of errors in the beginning):
   
  Mar 20 07:09:27 localhost kernel: usb 6-2: new full speed USB device using uhci_hcd and address 3
 Mar 20 07:09:27 localhost kernel: usb 6-2: device descriptor read/64, error -71
 Mar 20 07:09:27 localhost kernel: usb 6-2: device descriptor read/64, error -71
 Mar 20 07:09:28 localhost kernel: usb 6-2: new full speed USB device using uhci_hcd and address 4
 Mar 20 07:09:28 localhost kernel: usb 6-2: New USB device found, idVendor=08bb, idProduct=2706
 Mar 20 07:09:28 localhost kernel: usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
 Mar 20 07:09:28 localhost kernel: usb 6-2: Product: USB Audio DAC   
 Mar 20 07:09:28 localhost kernel: usb 6-2: Manufacturer: Burr-Brown from TI              
 Mar 20 07:09:28 localhost kernel: input: Burr-Brown from TI               USB Audio DAC    as /devices/pci0000:00/0000:00:1d.0/usb6/6-2/6-2:1.2/input/input13
 Mar 20 07:09:28 localhost kernel: generic-usb 0003:08BB:2706.0002: input,hidraw0: USB HID v1.00 Device [Burr-Brown from TI               USB Audio DAC   ] on usb-0000:00:1d.0-2/input2
   
  Now any attempt to plug it gives:


Spoiler



hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 3
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: new low speed USB device using uhci_hcd and address 4
 usb 6-1: device descriptor read/64, error -71
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 5
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 6
 hub 6-0:1.0: unable to enumerate USB device on port 1
 Monitor-Mwait will be used to enter C-3 state
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 2-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 8
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: device descriptor read/64, error -71
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 10
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: device descriptor read/64, error -71
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 12
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 14
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: device descriptor read/64, error -71
 usb 6-1: new low speed USB device using uhci_hcd and address 15
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 16
 usb 6-1: device descriptor read/64, error -71
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 6-1: new low speed USB device using uhci_hcd and address 19
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1
 usb 2-1: new high speed USB device using ehci_hcd and address 11
 hub 2-0:1.0: unable to enumerate USB device on port 1
 hub 2-0:1.0: unable to enumerate USB device on port 1
 usb 2-1: new high speed USB device using ehci_hcd and address 13
 hub 2-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1
 hub 6-0:1.0: unable to enumerate USB device on port 1


  Tried to reflow PCM2706, no luck.
  D+ and D- seem to be OK:
  3.3v side of L3 to D+: 1488ohms
  PCM2706 pin 23 to D+: 22ohms
  PCM2706 pin 22 to D-: 22ohms
   
  PCM2706 or PCB killed?
   
  Images:
  http://dl.dropbox.com/u/3311440/_MG_4227.JPG
  http://dl.dropbox.com/u/3311440/_MG_4228.JPG
   
  Output wires aren't connected to anything at the moment.


----------



## cobaltmute

Try giving your board a really good clean. The flux on it shouldn't be causing an issue, but it's been known to happen.


----------



## eprst

gave it isopropyl bath with some brushing, still same picture: gets detected for a very short period of time. Sometimes it connects-disconnects several times in a row if I keep it plugged in.


----------



## cobaltmute

Just as a question, on the dropbox pictures of the board, there is a very dark spot around the Rev f text.  Is that a scorch mark?
   
  Is the voltage at the 3V3 test point stable?


----------



## eprst

No, it was just a shadow. I've scorched miniUSB area a little while desoldering it, but there are no bridges there.
  3.3v is stable.
   
  UPD looks like more aggressive cleaning of that area has helped, no disconnects so far.. keeping my fingers crossed.
  UPD2 nope, still same problems :-/
   
  well, I'm out of ideas. Traced the schematics and re-checked all the connections once agian, re-soldered most of SMD parts, cleaned more flux from under them - still no luck. I'm close to giving up, ordering another kit and trying to build it anew..


----------



## akgfan

I ran a test in RMAA:
   

   
  Soundblaster audigy se is measured via loop with cordial cable with neutrik/rean gold jacks. The same cable was used for grubdac output which was connected to soundblaster audigy input.
   
  Not bad, but not good. Still it sounds miles better than audigy soundcard. And audigy soundcard uses digital noise removing, I think.
   
  And for cable guys ( 
	

	
	
		
		

		
			





 ) : my homemade cable with cheap cable and jacks makes the same results.


----------



## nullstring

Have you tried plugging it into a different computer or using a different operating system?
   
  This may sound silly, but I spent hours and hours trying to debug a different dac with a usb interface.
  It turned out that my usb driver or my usb chipset or something was faulty because it worked flawlessly on my laptop.
   
  Quote: 





eprst said:


> No, it was just a shadow. I've scorched miniUSB area a little while desoldering it, but there are no bridges there.
> 3.3v is stable.
> 
> UPD looks like more aggressive cleaning of that area has helped, no disconnects so far.. keeping my fingers crossed.
> ...


----------



## eprst

Yep, tried 3 different PC's and OS'es. After all I decided it will take me less time to build it again than to debug this one and ordered one more kit.
  In any case, thanks everyone for your help.
   
  UPD second attempt went flawlessly, this thing plays beautifully!
   
  Quote: 





nullstring said:


> Have you tried plugging it into a different computer or using a different operating system?
> 
> This may sound silly, but I spent hours and hours trying to debug a different dac with a usb interface.
> It turned out that my usb driver or my usb chipset or something was faulty because it worked flawlessly on my laptop.


----------



## Beftus

And another grubDAC sees the light of day... Uhmm, make that night. 

Had to do some debugging to get here though. :mad: I have Chaka Khan tickling my eardrums with _I Feel For You_ ATM.  Bloody hell, this thing rocks!

I opted for the capacitor tweak and installed Pana FC 330uF caps. I'm gonna put this inside a Hammond1455C801 enclosure. Now that it's working I'm gonna order engraved front and rear panels for it so it matches my Mini­^3.

I thought I had cut my teeth soldering the Mini^3 opamps. Well I was wrong... Soldering the tiny 1206's and 0805's proved quite a challenge. With a lot of patience and a steady hand I managed OK.

Many thanks to cobaltmute for sharing the design and TomB @ Beezar for selling the grubDAC kit and his detailed step-by-step guide.


----------



## tomb

Quote: 





beftus said:


> And another grubDAC sees the light of day... Uhmm, make that night.
> 
> 
> 
> ...


 

 Thanks back to you!  I'm sure cobaltmute will love seeing this post, too!
   
  Chaka Khan has some platinum pipes, doesn't she?  Bobby McFerrin made his living on imitating a lot of musical instruments, but Chaka Khan can almost perfectly mimic a trumpet.  "And the Melody Still Lingers On" was a tour-de-force with Dizzy Gillespie - my favorite.


----------



## islubio

Just ordered 2 kits and wonder if anyone tried adding a on/off switch to it?


----------



## cobaltmute

There was one I believe who tried it.  Replace L1 with a switch and a ferrite in-line.


----------



## Ikarios

Quote: 





cobaltmute said:


> There was one I believe who tried it.  Replace L1 with a switch and a ferrite in-line.


 

 Yes, I have my Grub installed this way and it's been working fine. here's a picture.
   

   
  Down by where L1 is supposed to connect you can see the in-line ferrite attached to the bottom pad. The grey wires lead to the SPST switch I'm using.


----------



## islubio

sry first time diy-er here
  what's a in line ferrite? only things i have done b4 is modding a psu to add a switch to short the psu to make it start


----------



## islubio

Is there an easier way or is that the easiest?
  Eg. like putting a switch to cut the 5v supply from usb?


----------



## cobaltmute

Wire from L1 pad to switch to ferrite to other side of the L1 pad (so the ferrite is mounted "in the line" with the switch.


----------



## cobaltmute

Quote: 





islubio said:


> Is there an easier way or is that the easiest?
> Eg. like putting a switch to cut the 5v supply from usb?


 


  That is what we are suggesting (unless you want to cut apart your USB cable, which I would not advise).
   
  If you are going to do a cable dac, you could put the switch between the 5V from the cable and the board.


----------



## islubio

oh ok now i get it now.
  would head down to local store find a ferrite i guess or is there any place i can easily salvage this part from?
  old cpu or modems?


----------



## islubio

Btw i purchased the mini usb version.
  Didnt notice that the led are not included. can i use any 3mm leds i have lying around?
http://cgi.ebay.com/120-Pcs-3mm-Red-Green-Blue-Yellow-White-LED-Light-12V-/110461530985?pt=LH_DefaultDomain_0&hash=item19b8053369#ht_5952wt_1139 had many of this left from last project


----------



## cobaltmute

the LED is included (I know this as I argued with tomb over which LED to put into the kit).  However the case is not.


----------



## islubio

Blue LED specially selected for the Hammond 1551HTBU (not included)
  i read it wrongly lol. i ordered the cases too hope it arrives asap.


----------



## Beftus

My GrubDAC in a Hammond 1455C801 case. Panels designed in Front Panel Designer. No frills.





Installed three Panasonic FC 330uF caps instead of the supplied ones. Didn't do a comparison. It sounds gorgeous, especially when combined with my Mini³.


----------



## Maverickmonk

That is a gorgeous grub! May I ask where you got the case? Everywhere I've found them they seem to be plain aluminum, but black is definitely more preferable in my book. I'd like to hijack your idea (immitation is the highest form of flattery, is it not?) but with a JDS Labs CMoy for an amp.


----------



## Beftus

I buy most of my stuff @ conrad.com, they sell both the silver and black versions.


----------



## Maverickmonk

Found it on mouser... I forgot to add BK to the parts number for black 
	

	
	
		
		

		
			





 oops!
   
  Many thanks, and again, excellent grub!


----------



## TheLaw

Hi,
   
  I don't know if this has been discussed before, but do solid polymer caps provide for the best sound? Anyone ever use anything else that they think sounded better?


----------



## Beftus

There's a bit of info on the big three caps here: http://www.diyforums.org/GrubDAC/GrubDACtweaks.php
The proof of the pudding is in the eating.


----------



## TheLaw

They are saying electrolytics are best but the polymers have better capacitances...but I'm sure you can get something that fits in there....


----------



## islubio

Just received the package. Very nicely packed. I was shock when i saw how small the case were. 
  Just soldered the 2 ic on n have bridges damn.. n i cant find my wick.


----------



## islubio

I have finished build the kit for my gf. But sometimes the there will be no sound but the led stays on. The grub dac is connected to an old receiver. When i was watching some shows suddenly there will be no sound after awhile and i would have to unplug n plug the grub in again. But the led stays on all the time n windows sees the device even tho there is no sound.


----------



## tomb

Quote: 





islubio said:


> I have finished build the kit for my gf. But sometimes the there will be no sound but the led stays on. The grub dac is connected to an old receiver. When i was watching some shows suddenly there will be no sound after awhile and i would have to unplug n plug the grub in again. But the led stays on all the time n windows sees the device even tho there is no sound.


 

 This really sucks!!!
	

	
	
		
		

		
		
	


	







  I've tried to post three times and got nothing but a blank post each time.
   
  Let me try again - check the connections around the PC.  The grubDAC can get knocked offline if loads are added or removed to/from the PC-USB buss.  Less common, but also something seen, is the grubDAC knocked offline from a new signal connection (connecting the RCA jacks) from a source on the USB buss.


----------



## islubio

hmm might be the av reciever will do a check when i go over her place again thanks for the help


----------



## Ikarios

So I just built a GrubCableDAC teaching a friend how to do SMD soldering, and turns out the unit isn't working. The LED turns on and it's recognized by the computer, somewhat - in Windows, it displays as "3- USB Audio DAC". My working Grub (in my SSMH) displays as USB Audio DAC so I don't know what the number means. More importantly, there's no sound. I never had to troubleshoot on my first Grub so I don't know what points to test for voltages. I reflowed most of the joints and doublechecked some of the IC soldering, and everything *looks* okay... I'm not sure what the problem could be. Help? Thanks!


----------



## Avro_Arrow

The number you see (3- USB Audio DAC) has to do with how many
  different ports you pugged the DAC into. The first time you plug the DAC
  into a USB port, that becomes #1. If you plug it into a different port, that
  becomes #2. It makes no difference which ports the are, just the order in
  which you used them.


----------



## islubio

Did u set the grubdac as default audio output?
   
  On both my pc n my gf's i have to set the grubdac as default else it will use the onboard or my soundcard.
  Also in my mediamonkey i have to set the grubdac as the audio out too.
   
  Hope this help


----------



## Ikarios

Quote: 





avro_arrow said:


> The number you see (3- USB Audio DAC) has to do with how many
> different ports you pugged the DAC into. The first time you plug the DAC
> into a USB port, that becomes #1. If you plug it into a different port, that
> becomes #2. It makes no difference which ports the are, just the order in
> which you used them.


 

 That makes sense.
   
  I know how to set the output in Windows and Foobar, since I use a GrubDAC as my main output source, and lately I've been testing a uDAC and a Music Streamer II, so I'm intimately familiar with the methods of output control. Thanks for the help, though.
   
  I tried reflowing the PCM2706 and Wolfson chips; neither did any good. I also double-checked all the passive component joints and they all look like they're workable solder joints (I won't say "good" because some of them aren't very pretty). Could flux or a bridge hidden deep within one of the ICs be a problem? Can I troubleshoot this via test points? I tried taking pictures of my ICs but my camera is terrible and none of the pictures I took are very useful for diagnosis. I'll post them anyway.
   
  http://img718.imageshack.us/g/dscf1313.jpg/


----------



## islubio

Maybe you would like to turn off the flash on your cam.


----------



## Ikarios

without flash, all my camera turns out are really blurry pictures. I need more light but I don't have light sources available right now. I'll try tomorrow if there's going to be sunlight.


----------



## ShinyFalcon

I see some potential bridging with the solder strings on the WM8524 and some pins that look unsoldered on the PCM2706.
   
  If you're getting 5V on VBUS and 3.3V on the 3V3 checkpoint, then everything is fine voltage wise. Check the crystal as well.
   
  Your WM8524 does look like it has pins making contact on two pads, as evident in dscf1304c.jpg.


----------



## Ikarios

Would I be able to see the bridging using a flashlight underneath the Wolfson chip? I don't see anything except the bridge that is created by the PCB design, both through the flashlight and upon visual inspection.
   
  There may be some unsoldered pins on the PCM2706, actually... it's hard to tell. I reflowed it a couple times with lots of flux so there's probably solder sitting between the pin and the pad but I was afraid of deep bridging so I didn't put too much solder. I can reflow that and see wehat happens.
   
  My Wolfson chip does not look like it has pins sitting on other pads; the PCM2706 is quite a bit off-center but I don't think any of the pins are touching other pads either. If something was wrong here, wouldn't the computer not detect it properly?
   
  I am getting around 4.82V from 0V to 5V on the USB connections, and from 0V to the 3V3 test point i am getting 3.3V.
   
  I'm not sure how to check the crystal 
	

	
	
		
		

		
			





 the soldering looks fine, I don't have a bridge from one of the pins to the top (as I recall someone had an issue with a while back). It's oriented correctly, that's about all I can tell.
   
  EDIT: I just discovered that output grounds are tied together. Is this typical? My RCA grounds measure 0R referenced to each other.


----------



## cobaltmute

I would say that the Oscillator is fine - it wouldn't recognize the PCM if it wasn't.
   
  If the PCM is recognized, but the board doesn't play sound, you likely have a bridge either on the WM8524 pins or on the PCM2706 pins that lead to the WM8524.
   
  If you look at the bottom of the board, just about the C4 label is three small traces with vias.  Check with your meter to ensure that those are not bridged together in any combination.  Also check those against the thin trace that starts at the via just to the right of the C11 label, which is also part of the I2S bus.
   
  And quickly looking over the pictures, it appears there is may be some bridging on the WM8524.
   
  And yes the output grounds are together - this is a single ended board with one ground.


----------



## islubio

I get very bad distortion when i set foobar wasapi to max volume out --> fiio e5.
  Esp when there's a lot of things play in the music. 
  Is the distortion cause by the grub or e5?
  also slight distort during start of playback
  There's less or no distorting only if i lower the output from foobar and increase the volume on the e5


----------



## cobaltmute

I'd wonder if the grubDAC is too "hot" for the e5. 
   
  What kind of headphones do you have?  If they are not extremely low impedance, you could try a direct connection from the grubDAC to see how the output is.  It won't sound as good as possible as they suggest a 2KOhm load, but it should give you an idea of what is going on.


----------



## islubio

i have lowered the output volume n it sounds ok
  but the slight distort at the start of every song still occurs, however only in the right channel.
  It hisses for 1-2 sec n plays normal again


----------



## Ikarios

Quote: 





cobaltmute said:


> I would say that the Oscillator is fine - it wouldn't recognize the PCM if it wasn't.
> 
> If the PCM is recognized, but the board doesn't play sound, you likely have a bridge either on the WM8524 pins or on the PCM2706 pins that lead to the WM8524.
> 
> ...


 

 The via connections (all three above C4 and the one to the right of C11) all test fine - my meter shows infinite resistance between all the points, in any combination. What pins on the PCM are connected to the Wolfson? I can try reflowing that; I'm a little more suspicious about it than I am with the Wolfson given the alignment issues, and the fact that I've reflowed the Wolfson several times with no apparent bridges.
   
  EDIT: Okay, I tried again after scraping between the pins on the Wolfson to ensure no barely-touching bridges were being made. No sound still. However I tried pressing on the PCM2706 while in use and I got a strange distorted sound! Yay... sometimes I would hear the music but it sounded quite distorted, with lots of "digital noise". I'll reflow the whole chip to make sure all connections are okay. Are there certain pins I should pay more attention to (i.e. the ones that go to the Wolfson)?


----------



## islubio

It seems that the distortion at the start of each song only occurs on foobar.
  with my mediamonkey there isnt such a problem, the distort only happens if i just started playing the first song or resuming after a pause or stop. 
  also the disortion is heard when the windows sound test was run or when the error sound is play.
  the sound playback nicely now with foobar wasapi at around 50-75% volume on my foobar.
   
  It also seems that the grub is very sensitive with the powerline.


----------



## Beftus

Quote: 





> It also seems that the grub is very sensitive with the powerline.


 


  Mine goes silent for a moment when I switch my SWR bass amp on or off. 
	

	
	
		
		

		
		
	


	




  Do you mean something like that?


----------



## cobaltmute

Quote: 





ikarios said:


> The via connections (all three above C4 and the one to the right of C11) all test fine - my meter shows infinite resistance between all the points, in any combination. What pins on the PCM are connected to the Wolfson? I can try reflowing that; I'm a little more suspicious about it than I am with the Wolfson given the alignment issues, and the fact that I've reflowed the Wolfson several times with no apparent bridges.
> 
> EDIT: Okay, I tried again after scraping between the pins on the Wolfson to ensure no barely-touching bridges were being made. No sound still. However I tried pressing on the PCM2706 while in use and I got a strange distorted sound! Yay... sometimes I would hear the music but it sounded quite distorted, with lots of "digital noise". I'll reflow the whole chip to make sure all connections are okay. Are there certain pins I should pay more attention to (i.e. the ones that go to the Wolfson)?


 
   
  I'd just try to make sure everything is down properly.


----------



## cobaltmute

Quote: 





islubio said:


> It seems that the distortion at the start of each song only occurs on foobar.
> with my mediamonkey there isnt such a problem, the distort only happens if i just started playing the first song or resuming after a pause or stop.
> also the disortion is heard when the windows sound test was run or when the error sound is play.
> the sound playback nicely now with foobar wasapi at around 50-75% volume on my foobar.


 

  This is very strange behavior.  The only time I've had weird noise out of foobar/WSAPI  is when playing with the buffers.
   
  As a question, what OS are you using?
   
  Quote: 





islubio said:


> It also seems that the grub is very sensitive with the powerline.


 
   
  Quote: 





beftus said:


> Mine goes silent for a moment when I switch my SWR bass amp on or off.
> 
> 
> 
> ...


 

  
  I've had one or two cases where I've had a grubDAC "shut-down" its output - but this has always been when it has been attached to an amp under construction in a test situation.  The Wolfson seems to be fairly rugged.


----------



## akgfan

Yeah, mine GrubDAC goes silent for a moment too when I insert or remove power adaptor from dsl router to the socket. Or another adaptor in 1m distance. I don't have metal case.


----------



## islubio

I m use windows 7.
  It happens on both my netbook and my gf's desktop. Both windows 7.(distort at start)
  It seems that every time where there's when there's a pause or stop in output to the dac. Distortion will come on when sound/music resumes
  Over at my gf place the grub gets knock offline pretty often i got a feeling it's cause of her powerline or her old receiver.
  the grub only gets knock offline when i turn on or off a power socket that is in parallel to the socket that is powering my adapter for my netbook.


----------



## Fishline

I've finished all the soldering, but ran into some problem.  I'd very much appreciate help!
   
  At first I can get the PC (WinXP Pro) to recognize the DAC, but no sound came out.  I did get 3.3v at the test point.  I tried re-flowing some solder joints, and now the PC doesn't even recognize the DAC.  I don't get any voltage at the test point, either.  All I get is the LED.


----------



## tomb

The solder looks a little thick on those IC's.  I suspect that you may have several bridges.  It sort of explains why you can get some of it to work, then not.  Keep re-flowing - without solder - and try to reduce that solder  build-up on the pins.  Refer to this description and the pics for a review of the technique needed on the pins with your soldering iron:
   
http://www.diyforums.org/GrubDAC/GrubDACsolder.php
   
  P.S. That low-pass filter does nothing without the capacitors on the output.  Just having the resistors there will most likely really degrade the sound.  Also - please use the second ground lead, if you can.  It will make it more reliably quiet.


----------



## cobaltmute

Quote:  





> P.S. That low-pass filter does nothing without the capacitors on the output.  Just having the resistors there will most likely really degrade the sound.  Also - please use the second ground lead, if you can.  It will make it more reliably quiet.


 


  The low pass filter caps are the ones on the bottom


----------



## akgfan

Quote: 





tomb said:


> Also - please use the second ground lead, if you can.  It will make it more reliably quiet.


 


  Could you please explain why? I don't have very good results in RMAA in stereo crosstalk which I find weird.


----------



## tomb

Quote: 





cobaltmute said:


> The low pass filter caps are the ones on the bottom


 

 Oops - sorry I missed that!
   
   
  Quote: 





> Could you please explain why? I don't have very good results in RMAA in stereo crosstalk which I find weird.


 
   
  Maybe it's because you don't have a sufficient ground connection?  OK, so I blew it on seeing the SMD caps on the bottom of your PCB.  Still, IMHO you're asking for trouble just using one ground wire.  Any "dodgy" connection whatsoever in that single ground wire and your whole output quality goes putz.


----------



## Spacehead

I have problems with my latest GrubDAC. It gets recognized sometimes, but mostly it is an unknown device. I lifted one or two pads in the pin 31 and scratched to the first layer in 25 and 26.  I just wonder, that when those are only ground connections, do I have other problems in there or should I just make sure the ground connections are good? If I need a jumper wire, where should I connect 25 , 26 and 31 ?
  In my opinion the other components are properly soldered, but I guess I could try reflowing them all. I just hope that the PCM2706 has not burned.
   
  P.S. I lost one PCM2706 somewhere. Such a large IC...


----------



## Ikarios

Quote: 





cobaltmute said:


> The low pass filter caps are the ones on the bottom


 

 On a somewhat-related note, what is the difference between using the MKP box caps in those positions vs. SMD? I had SMD caps in the GrubDAC that was in the SSMH I used for quite some time because they were 5 cents cheaper, and easier for me to solder/more convenient to clean. I have regular box caps in the one I'm currently building. I suppose the box caps will sound better but how big is the difference?


----------



## akgfan

Quote:  





> Still, IMHO you're asking for trouble just using one ground wire.  Any "dodgy" connection whatsoever in that single ground wire and your whole output quality goes putz.


 

 This was my first test:

   
  Now I use the same in this box:

   
  But results in RMAA are still the same:

   
  However, sound quality is much better than soundcard.


----------



## Spacehead

akgfan , don't worry about it. GrubDAC tests abnormally low on RMAA for some reason. Maybe it starts to oscillate or something. And, if it outputs 2V, then it would need attentuation before going to soundcard IMO
   
  Could somebody help me with my problem? The chip is possibly OK, because it first gets recognized, and then is lost, and gets unknown.
  I don't usually do such bad soldering job, but now I have a lot of stress that distracts me.
   
  Pics:
http://dl.dropbox.com/u/7337908/Grubdac/IMG_8263.JPG
http://dl.dropbox.com/u/7337908/Grubdac/IMG_8264.JPG
http://dl.dropbox.com/u/7337908/Grubdac/IMG_8265.JPG


----------



## Ikarios

Well, for one... R5 is missing. I would also try cleaning the board thoroughly with isopropyl alcohol (especially between the pins of the ICs), check with a flashlight to make sure no bridges are being made, and carefully scrape between pins to remove bits of solder and other crap that might be making a bridge.


----------



## Ikarios

Is there any harm in cleaning a completed board with acetone? I did it last time after I had soldered the sealed SMD parts but before I placed the through-hole parts and capacitors. I didn't clean my board very thoroughly this time (lack of tools and time) so I completed my board before cleaning off any flux before placing capacitors and other stuff. I know acetone is a pretty strong solvent but will these solid polymer and film caps be affected?


----------



## tomb

Quote: 





> akgfan , don't worry about it. GrubDAC tests abnormally low on RMAA for some reason. Maybe it starts to oscillate or something. And, if it outputs 2V, then it would need attentuation before going to soundcard IMO


 
  I agree that someone should not worry about it.  I don't think it's oscillating, though.  After years of messing with RMAA, I'm convinced that it does not respond well to anything without a feedback loop.  Put a cheap amp or DAC with an opamp feedback loop on RMAA and it will test beautifully.  Put anything that sounds good (great?) without a feedback loop and it will test like cr*p.  None of that is indicative of the actual sound quality.  I think RMAA is valuable for tweaking a final design - trying new components to lower distortion, etc., or pinpointing noise in certain areas of the audio band, etc. - but that's only when comparing with before and after tests of the same device.  Using it as some sort of absolute standard of comparison among different designs is very problemmatic.
   
  Quote: 





> Could somebody help me with my problem? The chip is possibly OK, because it first gets recognized, and then is lost, and gets unknown.
> I don't usually do such bad soldering job, but now I have a lot of stress that distracts me.
> 
> Pics:
> ...


 
   
  Quote: 





> Well, for one... R5 is missing.  I would also try cleaning the board thoroughly with isopropyl alcohol (especially between the pins of the ICs), check with a flashlight to make sure no bridges are being made, and carefully scrape between pins to remove bits of solder and other crap that might be making a bridge.


 
  R5 is only for the LED.  If he's not using an LED, then there is no need for it.  I agree with the rest of your suggestions, however.  The joints actually look cold to me - maybe turn the temperature up on the iron and try some re-flowing to clear some of those pins?


----------



## cobaltmute

Quote: 





ikarios said:


> On a somewhat-related note, what is the difference between using the MKP box caps in those positions vs. SMD? I had SMD caps in the GrubDAC that was in the SSMH I used for quite some time because they were 5 cents cheaper, and easier for me to solder/more convenient to clean. I have regular box caps in the one I'm currently building. I suppose the box caps will sound better but how big is the difference?


 

 In my personal builds, to my ears, in my system,  the ceramic caps sounded a bit more "bright" than the box caps.


----------



## Beftus

Quote: 





ikarios said:


> Is there any harm in cleaning a completed board with acetone? I did it last time after I had soldered the sealed SMD parts but before I placed the through-hole parts and capacitors. I didn't clean my board very thoroughly this time (lack of tools and time) so I completed my board before cleaning off any flux before placing capacitors and other stuff. I know acetone is a pretty strong solvent but will these solid polymer and film caps be affected?


 


  Steer clear of acetone. A lot of plastics don't like it. Those film caps might be affected. Stick with isopropylalcohol for flux removal.


----------



## jdkJake

Plus acetone will usually remove part markings as well as most stencil on solder masks.
   
  Also toxic as hell and really hard on your skin. Avoid skin contact and breathing the vapors at all cost.
   
  Works well though...


----------



## Ikarios

Quote: 





jdkjake said:


> Plus acetone will usually remove part markings as well as most stencil on solder masks.
> 
> Also toxic as hell and really hard on your skin. Avoid skin contact and breathing the vapors at all cost.
> 
> Works well though...


 

 Nah, acetone isn't really toxic, unless you're in an unventilated area (which is dumb with any kind of solvent, really). We use it all the time to clean stuff in the school lab, works wonders as an organic solvent. It's relatively safe on this production board too since I've used it before... 
	

	
	
		
		

		
		
	


	



   
  But I suppose dissolving plastics is a problem, as I wasn't sure how the film caps react to acetone. I guess I'll just go with the tried and true IPA then.


----------



## Spacehead

I think I managed to get the previously mentioned GrubDAC working. I hope it stays that way. I am relieved for now.


----------



## Spacehead

hmm there is a problem still... Now I have short between VDD and GND. I have managed to pinpoint it to either one of the top side ICs. I checked DAC datasheet and it should have any short related to VDD and GND because there one pin between those.
  But PCM2706 has. I think my PCB has damaged between pins 1-2. Is it possible to make a cut between those, to severe the connection?


----------



## Ikarios

Well, after settling in back home I finally set up my soldering iron agan and got to work on my busted Grub. An hour later, after many reflows and much alcohol and toothbrush scrubbing, I plugged it in and finally - no crazy static, just clean music! Yay!
   
  Has anyone compared a GrubDAC with an HRT Music Streamer II? I'm trying to do a comparison but it's a little difficult since the GrubDAC seems to be a little louder than the MSII (basics check: this means that the grub output voltage is slightly higher than the MSII [nominal output voltage 2.25V}, right?). So far it doesn't look good... for the MSII.


----------



## islubio

I have a gurb with led working but my netbook does not detects the dac


----------



## tomb

Quote: 





islubio said:


> I have a gurb with led working but my netbook does not detects the dac


 

 Can you get us some pics?  The PCM2706 is the chip that governs the interface to the PC.  If you have shorts or other problems around the pins on that chip, it won't be recognized.  Unfortunately, a working LED work confirms little beyond the fact that the USB connector is OK.


----------



## H22

Quick question, my grubdac works fine with my XP computer 

But recently got a new Mac with OSX, and Mac recognizes it, but I have no clue as to how to get it to work, any ideas?


----------



## Yoga Flame

Quote: 





h22 said:


> Quick question, my grubdac works fine with my XP computer
> 
> 
> 
> ...


 

 option+click the volume icon on the OSX menu bar.


----------



## H22

Awesome, thanks


----------



## Insighter

Quote: 





akgfan said:


> But results in RMAA are still the same:
> 
> 
> However, sound quality is much better than soundcard.


 


 Could you please give full RMAA results (especially THD and IMD graphs)? Character of distortion is more important.
  Also Audigy SE have bad quality resampling on 44.1kHz, better use 48kHz for measurements.


----------



## Insighter

When I knew about GrubDAC yesterday, I immediately ordered kit. Hope, it will be far better than my previous[size=x-small][size=x-small] [/size][/size][size=x-small]attempts to find cheap and good or decent sounding compact DAC (PCM2902 and PCM2704 were really bad).[/size]


----------



## Insighter

Erik, how do you think - using of separate voltage regulator for analog part can improve performance?


----------



## cobaltmute

Quote: 





insighter said:


> Erik, how do you think - using of separate voltage regulator for analog part can improve performance?


 
   
  Sorry for the delay in responding, but I was away without internet.
   
  Use of seperate regulators for both analog and the clock may improve performance.  How much, I cannot say specifically as it would depend upon the regulators and I have never tested.


----------



## nightanole

Well im a procrastinator.  I have a rev R1 grub that i finaly found a use for.  However looks like 4 revs happened while i was gone.  Is there anything i need to do before i finish soldering it?  The new rev doesnt use a bipolar crystal.  Looks like the only real change is psel/fsel was connected to ground, now psel/test is connected to vdd, i dont know if i can do that mod.


----------



## cobaltmute

Quote: 





nightanole said:


> Well im a procrastinator.  I have a rev R1 grub that i finaly found a use for.  However looks like 4 revs happened while i was gone.  Is there anything i need to do before i finish soldering it?  The new rev doesnt use a bipolar crystal.  Looks like the only real change is psel/fsel was connected to ground, now psel/test is connected to vdd, i dont know if i can do that mod.


 
   
  If you have an original rev 1 board, you should be perfectly fine with the BOM/etc as was originally posted.


----------



## Insighter

I've made and combine RMAA measurements using SB Live 5.1 and SB Live 24 and can say that:
   
  THD is around 0.0031% (-90dB, better than in datasheet) or less
 IMD+noise is around 0.0064% or less
  S/N ratio is -100dB, or better, and noise floor is very clean (Murata beads do their job well  )

  
  [size=x-small]Measurements must be done at max volume (otherwise additional distortion would be). [/size]
  [size=x-small][size=x-small]Howewer, it can overdrive input, better to use attenuator or good headamp with volume regulation.[/size][/size]
   
  So, specs better than AlienDAC and BantamDAC have.


----------



## dhaninugraha

my kit has arrived! yay! ordered them from beezar.com on 8/8 and the local post office sent me a pickup notice yesterday. picked the package up this morning. almost a month (first-class mail, oh well), but it was worth the wait. kudos to tomb for the swift service and overkill packaging! 

time to get myself a new helping hand, and if the planets all line up, spare the weekend for another all-nighter. this is going to be fun.


----------



## Beftus

Listening to _Return of the Headhunters_ right now with my GrubDAC feeding my 12AU7 Starving Student. What a great sounding setup.
   
  Good luck assembling your GrubDAC, it's a bit fiddly to make but once you've got it working you are rewarded with a very fine DAC.


----------



## dhaninugraha

the itch was irresistible, so I built the grubDAC last Sunday. took me around 3hrs (it was my first time doing a project with so much SMT parts), and it immediately worked the first time I plugged it into my MacBook. pictures will follow.

will have to come home sometime this week, as I am intrigued about how it's going to sound combined with the WA6.


----------



## funkydude079

Is it possible to swap the mini usb port with a micro usb port?


----------



## jdkJake

funkydude079 said:


> Is it possible to swap the mini usb port with a micro usb port?




The mini-b USB connector is pin compatible with a micro-b connector.

Now finding a part that fits the same PCB form factor may be more difficult. But, perhaps not, I have not looked,


----------



## cobaltmute

jdkjake said:


> The mini-b USB connector is pin compatible with a micro-b connector.
> 
> Now finding a part that fits the same PCB form factor may be more difficult. But, perhaps not, I have not looked,




This may be difficult. Last I looked most of the Micro-USB connectors were surface mount.


----------



## funkydude079

I just finished making my grubdac but I'm not getting any sound. When I plug it in my computer, I can see it. I'm getting 3.26 V when I measure from 0 to the 3V3. Does anyone know what the problem is?


----------



## jdkJake

How about some pictures of the top and bottom of the board?

Lots of light and as much focus as you can muster.


----------



## funkydude079

Are these photos ok?


----------



## jdkJake

The middle photo (top of the board) needs to be in better focus. If your camera has a macro mode, now is the time to use it.
   
  The third picture helps a lot, but, we still need a better shot of the top. Especially of parts U1 and U3.


----------



## hitman47

Quote: 





funkydude079 said:


> Are these photos ok?


 

 That looks like a huge bridge on the smaller chip there, you should fix that and try again


----------



## funkydude079

Thanks for the advice. I'm going to be pretty busy for the next few days so I probably can't try anything until like thursday or friday. I'll definitely try taking a closer look at the smaller chip and getting better pictures up.


----------



## lehtinel

Started building mine today, a hassle for a first timer to get a bridgeless solder for the PCM chip. I completed the build and fired it up. Now the TPS chip gets super hot, I havet had the DAC on for more than 10-20sec. so I would not fry anything. Tried solering the TPS againg mut that didn't help.

Pictures to come.


----------



## cobaltmute

Check for solder bridges. On both the TPS and after it. Hot = drawing too much current from the TPS, which implies short to ground somewhere.


----------



## lehtinel

Reflowed TPS chip, PCM chip, Wolfson chip, oscillator chip and L1 = can't get it going. The TPS chip usually gets hot upon connecting the DAC, I then shut it down. A couple of times now I've had it running withouth the TPS getting hot, my voltage at 5V is right at 4.86V, but the 3.3V is at 0.45V. 

Pics:







Dirty board, I know, only have PRF 6-68 "dry" electronics cleaner that doesn't do that good of a job


----------



## cobaltmute

Check all your pins near pin 1 (the dot) on the PCM2707. Looks like you may have some bridge their.

Test the resistance between the 3v3 point and 0V - should be high - if not you're tracing bridges.


----------



## lehtinel

cobaltmute said:


> Check all your pins near pin 1 (the dot) on the PCM2707. Looks like you may have some bridge their.
> Test the resistance between the 3v3 point and 0V - should be high - if not you're tracing bridges.




Reflowed the pins close to pin 1 and measured about 18 ohms betveen 3.3V and 0V - still, on pluging in the DAC the TSP got hot again.


----------



## Avro_Arrow

I'd clean up C7.
  The solder overlaps an adjacent trace and the solder mask does
  not alway prevent a short.
   
  Edit: Checked a bare board...they are supposed to overlap.


----------



## lehtinel

avro_arrow said:


> I'd clean up C7.
> The solder overlaps an adjacent trace and the solder mask does
> not alway prevent a short.
> 
> Edit: Checked a bare board...they are supposed to overlap.




ARGH! Desoldered C7 to get to see the TPS chip connections better and *snap* said the tweezers and *boing* went the cap. :confused_face(1): where to get a new one here in Finland, buuh.


----------



## lehtinel

Found a source for 1uf 25v 805 SMD caps so I think I'll order a replacement from there, might also order a TPS79333 chip as I suspect I might have killed that also.


----------



## Avro_Arrow

I've had that happen too...
	

	
	
		
		

		
			




   
  Quote: 





lehtinel said:


> ARGH! Desoldered C7 to get to see the TPS chip connections better and *snap* said the tweezers and *boing* went the cap.
> 
> 
> 
> ...


----------



## lehtinel

Placed an order today on the exact same capaciotor as shipped with the DAC, 10pcs. so I will not be as disturbed if I loose a few  Two TPS chips also coming up. Shameful thing about the order was ofcourse that the shipping vas 70% of the price, got away cheap anyways so, no big deal.
   
  I really hope this will sort out my GrubDAC.


----------



## lehtinel

Got the spare parts, soldered the C7 in, cleaned up the pins on the TPS-chip, plugged it in, 0.13V at 3.3V point. Shut it down and check for bridges, what I see is a nasty bridge over from the last pin on the TPS-chip to the C7. Can't get the solder out, it's pinned to the surface of the PCB and formed a clean trace along the PCB tracing.
   
  ARGH! So annoying I set the whole thing aside.


----------



## lehtinel

Tinkered with the DAC today. No progress though. A new TPS chip in place i checked for solder joints on the chips, got a 0 - 3.3V resistance of some 70ohms. When I plugged the DAC in the port the Wolfson chip gave out some smoke - bad news I guess.
   
  Will se if I'll place a new order on a second kit and do one from scratch.


----------



## tomb

Quote: 





lehtinel said:


> Tinkered with the DAC today. No progress though. A new TPS chip in place i checked for solder joints on the chips, got a 0 - 3.3V resistance of some 70ohms. When I plugged the DAC in the port the Wolfson chip gave out some smoke - bad news I guess.
> 
> Will se if I'll place a new order on a second kit and do one from scratch.


 
  I'm sorry you're having such bad luck with it.


----------



## lehtinel

Quote: 





tomb said:


> I'm sorry you're having such bad luck with it.


 


  No problem Tom, my entry into the SMD-world hasn't been the smoothest, but it won't stop me from pushing on


----------



## Atilla

Well. I've got a problem  
   
  I assembled the board. Took a bit of time, but it went great. I powered it up, LED is on, no detection. 
   
  After some quick debugging, here's the status. Regulator gets hot, therefore there's a short somewhere. TP1 to ground is 0 ohm. Bad. 
   
  Reflowed the usual suspects. Even though they did look quite shiny already. No chance. I resoldered a few caps that I suspected as well, but no luck. 
   
  I'd love a second pair of eyes to help me out. Here are some macro shots:
   
  https://picasaweb.google.com/theatilla/BrokenGrubDac?authuser=0&feat=directlink
   
  It's something on the left side of the r6, r4, r1 arc, since on the right side there's a bit of resistance.


----------



## tomb

Quote: 





atilla said:


> Well. I've got a problem
> 
> I assembled the board. Took a bit of time, but it went great. I powered it up, LED is on, no detection.
> 
> ...


 

 Sorry you're having trouble, but can you check that link to your pics?  All I get is a "Page Not Found" error.


----------



## Atilla

Sorry, google was being overprotective. This should work now:
   
  https://picasaweb.google.com/theatilla/BrokenGrubDac?authuser=0&authkey=Gv1sRgCNOl7eeA_ouTugE&feat=directlink


----------



## cheapskateaudio

I've got a grub kit on the way, woot!
   
  Will a 35 watt iron be to hot for the surface mount chips?


----------



## tomb

Quote: 





cheapskateaudio said:


> I've got a grub kit on the way, woot!
> 
> Will a 35 watt iron be to hot for the surface mount chips?


 

 Most likely, unfortunately - although maybe some others can speak up if they've had success with one.  I think 15W is a maximum if you're using something without temperature control.  More important probably, is a small tip - I use a 0.8mm chisel tip on my Hakko for SMD work.
   
  All this and more is detailed on the various Bantam, Grub, and Skeleton DAC websites:
BantamDAC Overview
GrubDAC Overview
SkeletonDAC Overview
  Look under the "What's Needed ..." section on the above pages, also - refer to the "Preparation" page under "Construction."
   
  Another key is to use a flux pen for the best results and eutectic (63/37), rosin core solder not much bigger than 0.025" diameter, if you can help it.


----------



## Avro_Arrow

I agree with Tomb...a 35 watt iron will be way to hot for smd work.
  
  Quote: 





cheapskateaudio said:


> I've got a grub kit on the way, woot!
> 
> Will a 35 watt iron be to hot for the surface mount chips?


----------



## cheapskateaudio

Thanks for the responses. I guess I will look into getting an adjustable temp soldering station.


----------



## mugdecoffee

I soldered this and several other surface mount DACs with a unregulated 40W iron.  I think you just have to make sure not to heat anything for too long.


----------



## cobaltmute

You can use a unregulated iron.

The quality of my work (and therefore enjoyment of the hobby) went up when I got a regulated station.


----------



## cobaltmute

atilla said:


> Sorry, google was being overprotective. This should work now:
> 
> https://picasaweb.google.com/theatilla/BrokenGrubDac?authuser=0&authkey=Gv1sRgCNOl7eeA_ouTugE&feat=directlink




I don't see anything obvious - might be some bridge hiding from an angle I can't see.


----------



## lehtinel

There's a lot of solder on the chips atleast, might easily do a bridge. Hard to see. 
  (ugh, not that Im an expert, still confused and sad for mixing up my own GrubDAC, it's payday tommorrow anyway so...


----------



## Atilla

Hm, the chips have a lot less solder than my Bantams and I've got 3 of them working (slowly learning how to solder those in the process). I think I'll remove all caps carefully, numbered and then check for bridges again. If they're there, it's the chips. I'm pretty confident of them, but you never know.


----------



## akgfan

Guys, I did it with 75W soldering gun without any problem. You just need to use 0.8mm tip and cut solder (0.6mm) into little pieces (2mm or so). ICs were quite simple to my surprise.


----------



## cheapskateaudio

Well, my grub dac turns on, and is found by windows, I can select it as the output device in foobar, but all I hear on the output is a hum and some light static, any ideas? Nothing gets warm to the touch, either.


----------



## tomb

Quote: 





cheapskateaudio said:


> Well, my grub dac turns on, and is found by windows, I can select it as the output device in foobar, but all I hear on the output is a hum, any ideas?


 

 If Windows recognizes it and you can select it as an output device, then the PCM2706/7 (U1) is performing correctly - so is the regulator (U2).  So, focus on the Wolfson chip for bridges or pins not making contact.


----------



## cheapskateaudio

Quote: 





tomb said:


> If Windows recognizes it and you can select it as an output device, then the PCM2706/7 (U1) is performing correctly - so is the regulator (U2).  So, focus on the Wolfson chip for bridges or pins not making contact.


 


  Woot, it works now! Sounds awesome...
   
  Initial impression of the sound is that there is solid and abundant bass and excellent detail throughout the sound spectrum. Very revealing and transparent in combination with the O2, almost disturbingly so. 
   
  The O2 + Grubdac + HD448's is a pretty nice sounding combo, very airy and extended sounding, I've never heard the HD448's sound this good, I'm impressed. Still don't like the O2 driving the HD650's even with grubdac, but it is an improvement over the uDac 1/2 in pretty much every way. 
   
  My one complaint is that it occasionally sounds a bit "digital", I don't think it's the grubs fault necessarily, just certain tracks.
   
  BTW, thanks for your help Tomb!


----------



## Handy Ray

Built 3 of these DAC's over some period of time last year.  I must say, they are great sounding for the price.  Fantastically fun and simple build process too!  All thanks to its creators!!


----------



## cheapskateaudio

Quote: 





handy ray said:


> Built 3 of these DAC's over some period of time last year.  I must say, they are great sounding for the price.  Fantastically fun and simple build process too!  All thanks to its creators!!


 


  Good job man, I think I will build another as well, but .... I need to get a magnifier first, lol. I felt like I was going blind building this thing. I agree though it was a fun build, definitely a different process with the surface mount stuff, each piece is it's own tiny adventure.


----------



## akgfan

Quote: 





cheapskateaudio said:


> ...each piece is it's own tiny adventure.


 

 Yeah, especially when you try to find that tiny SMD in carpet.


----------



## tomb

Quote: 





akgfan said:


> Yeah, especially when you try to find that tiny SMD in carpet.


 

 Isn't that the truth?  My worst episodes are when my tweezers try to play tiddly-winks with the TPS regulator.  For some reason, that's the one I have the most bad luck in handling.
   

  
   
  Quote: 





cheapskateaudio said:


> Woot, it works now! Sounds awesome...
> 
> Initial impression of the sound is that there is solid and abundant bass and excellent detail throughout the sound spectrum. Very revealing and transparent in combination with the O2, almost disturbingly so.
> 
> ...


 

 So glad you got it working!


----------



## Ikarios

A tip for those who tend to lose SMD chips in carpet: get a vacuum cleaner with a hose attachment and cover it with some light cloth (pantyhose probably works best, cheesecloth may also work) and work over the area where you might have lost it. The chip should get sucked in by the suction but will be trapped by the cloth.
   
  Also a 35W iron shouldn't be too bad, if you have a steady hand and have worked with SMD pieces before. I've done two  GrubDACs on my 25w Hakko Dash with no trouble at all, but for a first-time SMD solderer I would not really recommend it. Desoldering braid and lots of flux is your friend.


----------



## Handy Ray

Definitely a mag is useful.  After building these I felt like I became tunnel visioned and near sighted for quite a while.
   

  
  Quote: 





cheapskateaudio said:


> Good job man, I think I will build another as well, but .... I need to get a magnifier first, lol. I felt like I was going blind building this thing. I agree though it was a fun build, definitely a different process with the surface mount stuff, each piece is it's own tiny adventure.


----------



## cheapskateaudio

Quote: 





akgfan said:


> Yeah, especially when you try to find that tiny SMD in carpet.


 

 Wooot! I'm not the only one who did that!


----------



## zeffa

Built the grubDAC last night. I was pretty happy with the results for my first time doing SMD soldering. Anyway, initial power on seemed to work properly - all the voltages were correct, and the LED turned on. When wired up though, I'm getting sound, but only out of the left side. I tried on Mac and PC and it was the same result. I've attached pics of the PCB. Any thoughts?


----------



## tomb

Two possibilities:
  1. You've mis-wired the output connector.
  2. The WolfsonDAC chip is messed-up/soldered bad.  Check the furthest pin opposite the dot.  That would be the pin that's closest to the Right channel V-D resistor (blue one) and the C9 capacitor.  That's the LINEVOUTR pin.


----------



## zeffa

Hi Tom, thanks for the advice! On closer inspection of the Wolfson chip, I noticed that there wasn't any solder at the LINEVOUTR pin you mentioned. Now that its been on soldered properly, everything seems to be working! Thanks again!


----------



## tomb

Quote: 





zeffa said:


> Hi Tom, thanks for the advice! On closer inspection of the Wolfson chip, I noticed that there wasn't any solder at the LINEVOUTR pin you mentioned. Now that its been on soldered properly, everything seems to be working! Thanks again!


 

 That's great!  Glad you were able to fix it!


----------



## hitman47

Hi everyone, I finished my second grubDAC about a week ago (after messing up the first one already) and I'm having trouble again... Something's causing a short and I'm not sure how to check what it could be, Tomb advised me to ask my questions here as more people are probably looking at this thread. Details are in my thread at http://www.head-fi.org/t/573197/mosfet-max-tube-biasing-issues-solved-now-about-grubdac-issues/45, thanks in advance for the help!


----------



## tomb

Quote: 





hitman47 said:


> OK, yeah I thought that because of the way caps work, there should only be a resistance showing up at the beginning as it's being charged (whichis what happens with C5). I'm just not sure how to check what's causing the short, as the VRM is turned off by overcurrent protection (I'm assuming) so measuring currents/voltages won't do the trick I think and checking for resistance across caps (they're usually what's connected to ground) doesn't work as you told me... I'm also gonna leave a link to this thread in the grubDAC thread, thanks for the tip.


 

 The difference in the caps is probably which ones are charged (low resistance) and which ones aren't (high resistance initially).  C5 is on the same circuit as the LED, so it probably drains every time, whereas the other caps could get a partial draining, only.
   
  Can you be more specific as to the problem besides just "the short?"  What is telling you there's a short ...
   
   
  P.S. Measuring resistances is fine for troubleshooting.  Just don't do it when the DAC is plugged in and don't try it again on capacitors.


----------



## hitman47

I figured it was a short based on what cobaltmute told me in my thread - the LED lights up, but it flickers and there's only a tiny voltage on the 3V3 point while the VRM gets hot as hell. And if I can't measure resistances in caps to determine if they're busted, I'm unsure how to find the short, since pretty much all points prone to causing a short are caps connected to ground as far as I can see.


----------



## tomb

Quote: 





hitman47 said:


> I figured it was a short based on what cobaltmute told me in my thread - the LED lights up, but it flickers and there's only a tiny voltage on the 3V3 point while the VRM gets hot as hell. And if I can't measure resistances in caps to determine if they're busted, I'm unsure how to find the short, since pretty much all points prone to causing a short are caps connected to ground as far as I can see.


 
  Here's some principles to guide you in troubleshooting:
   
  1. The ground plane is the ground (sounds redundant, I know).  In this case (sort of an unofficial standard), Ground is negative (-).
   
  2. Traces that are not connected to the ground plane are of opposite polarity from the ground.  That means they're positive (+).
   
  3. Placing DMM probes connecting any two points of 1) the ground plane, and 2) a trace or a part of component connected to a trace - should measure some definite resistance, as dictated by the components in the path between the two DMM probes.  I was going to say capacitors are exempt from this rule, but in actuality - you're trying to measure pads on the PCB vs. the ground plane.  It won't matter if you measure a capacitor for resistance to the ground plane in this instance, because even a capacitor will have "some" resistance other than zero.\
   
  3.a. To make this easy, pick a Ground point for one of your probes and simply keep it there.  Anything connected to the ground plane should have zero resistance to this point.  "OG" should suffice, for instance.
   
  4. If you measure anything close to -zero- between two points as described in #3), then you have a short.
   
  5. Try to follow the schematic for the GrubDAC: http://www.diyforums.org/GrubDAC/GrubDACschematic.php.  If the voltage regulator is getting super-hot, look for the circuit of the voltage regulator from the power-in point (the USB connection) to the regulator itself.  That will be the circuit path for powering the voltage regulator.  You may need to follow the output path of the regulator - from its output to the component that its supplying, but worry about 2nd, not 1st.
   
  6. Once you have the schematic path pinpointed for your part in question (the regulator), try to make sense of the schematic with the actual PCB.  Look at either the layout - http://www.diyforums.org/GrubDAC/GrubDAClayout.php, or the board photos - http://www.diyforums.org/GrubDAC/GrubDACboard.php, so that you understand how the circuit on the PCB goes exactly how the schematic shows it.  IOW, if you've identified the path on the schematic for the voltage regulator, then look for the components in that path on the PCB.  See if you can find the traces on the PCB that connect all of the components in that path on the schematic.
   
  7. Measure the resistance of those component connections - with ground - all along that path that you've identified.  The values are not important when reading resistance.  What's important is whether you read any two points along that path, between a trace and the ground plane, that are -zero-.  THAT'S YOUR SHORT.
   
  Give it a try and let us know.


----------



## hitman47

Well, it seems C14 is at fault. I get practically 0 resistance from both sides to ground (I get a value of 1.4 ohms, which is the same as when I just touch the leads together). I'm gonna replace it with the one from my old build and see if that fixes the issue. Thank you very much for your very helpful tips, I'll let you know how it goes!
   
  Edit: I replaced it, and the same thing happened again (albeit only after a few seconds as far as I could see, at the beginning the light wasn't flickering). What could cause that cap to blow continuously (the resistance to ground is 0 again, and it wasn't on the first one I built, I measured it before taking the cap out)?
   
  Edit2: After thinking about it (and having another look at the schematic), I think it's probably C15 after all since it's in parallel to C14.
  Edit3: Replaced C15, no improvement. It could also be C6 or C10 but somehow I doubt that. I've noticed that the PCM chip gets hot as well, so currently my bet is on that being fried. I'm gonna try and see if I can get a replacement somewhere, but I'm not sure it's worth it. This is really sad since it's already my second failed attempt and I was planning on giving my dad a Mosfet-Max with a grubDAC for christmas which isn't gonna work out from how it looks now.
   
  Well, I managed to replace the chip with the one from the very first board I tried to assemble and messed up because I had such crappy soldering equipment. Now the PC says the device malfunctioned, so I hope it's just a badly soldered pin that can be fixed. I'll go try again.


----------



## akgfan

I've just got a bit of frightening experience. I was listening internet radio through grubdac and connecting my printer through usb port. Suddenly, no sound. I tried connecting and dissconecting grubdac for a few times, checked fuse in my amp - nothing. It didn't work for a few minutes. Then it came back to life again! Uff...


----------



## tomb

Quote: 





akgfan said:


> I've just got a bit of frightening experience. I was listening internet radio through grubdac and connecting my printer through usb port. Suddenly, no sound. I tried connecting and dissconecting grubdac for a few times, checked fuse in my amp - nothing. It didn't work for a few minutes. Then it came back to life again! Uff...


 

 Yes - this is something I should perhaps document on the GrubDAC website.  Plugging or unplugging other items on the PC's USB buss will knock a GrubDAC offline - momentarily.  Most likely, if you simply waited instead of connecting/disconnecting, you would've found it "re-appear" as a connected USB device.
   
  In any event, as you just saw - it's a completely harmless nuisance.


----------



## hitman47

WOOOOOHOOOOOO It's working!!! I reflowed some bad looking pins on the newly installed U1 (still can't believe I managed to replace it) and now everything works without a hitch! Thanks Tomb and everyone else for your help and merry christmas!


----------



## tomb

Quote: 





hitman47 said:


> WOOOOOHOOOOOO It's working!!! I reflowed some bad looking pins on the newly installed U1 (still can't believe I managed to replace it) and now everything works without a hitch! Thanks Tomb and everyone else for your help and merry christmas!


 
  Merry Christmas to you!  Glad you got it working!


----------



## akgfan

Quote: 





tomb said:


> Yes - this is something I should perhaps document on the GrubDAC website.  Plugging or unplugging other items on the PC's USB buss will knock a GrubDAC offline - momentarily.  Most likely, if you simply waited instead of connecting/disconnecting, you would've found it "re-appear" as a connected USB device.
> 
> In any event, as you just saw - it's a completely harmless nuisance.


 
   
  I normally plug other usb devices and it stops playing for just about half of a second. But this time I thought it is dead. I used different power plug for printer so I thought it has something to do with ground loops and I damaged it.


----------



## mmcaleer

Finished my DAC.  I am only getting output on the right channel and NO bass.  Any recommendations?
   
  Thanks,
   
  Mike


----------



## tomb

Quote: 





mmcaleer said:


> Finished my DAC.  I am only getting output on the right channel and NO bass.  Any recommendations?
> 
> Thanks,
> 
> Mike


 

 No bass may just mean you don't have both channels.  (Deep bass is mostly non-directional in stereo and depends on the combination of both channels for full response.  That's why single subwoofers work instead of needing pairs.)  Anyway,  for some reason this has cropped up at least three times in the last few days.  You can look in this thread a couple of pages back or check the right-most pins on the Wolfson chip.  The top pin on the right side (USB connector down) is the Left output for the DAC.  The bottom pin on the right side is the Right output.  If the particular channel pin is not actually soldered to the pad (this can be easy to miss) or is bridged to something else, then you won't get any sound out of that channel.


----------



## mmcaleer

Thanks Tom,
   
  I will check that first.  I took the DAC to work and looked at it under a scope and did have two bridges on the TI chip.  I fixed those.  I will make sure I soldered the Wolfson completely.
   
  Mike


----------



## mmcaleer

No luck.  I reflowed both chips with no luck.  I have one channel and it sounds like it is far away, in a tunnel and a "tinny" sound.  I will take it back to work tomorrow and look at it again under the scope and take close up photos.
   
  Mike


----------



## tomb

Quote: 





mmcaleer said:


> No luck.  I reflowed both chips with no luck.  I have one channel and it sounds like it is far away, in a tunnel and a "tinny" sound.  I will take it back to work tomorrow and look at it again under the scope and take close up photos.
> 
> Mike


 
  Yep - I think we need to see some of those pics.  Hopefully, cobaltmute will look in as well.


----------



## mmcaleer

Here are the photos.  Anything pop out at you?  I checked every pin under a Mantis scope to make sure there were no bridges and that every pin was soldered securely.


----------



## tomb

Quote: 





mmcaleer said:


> Here are the photos.  Anything pop out at you?  I checked every pin under a Mantis scope to make sure there were no bridges and that every pin was soldered securely.


 

 Geez - the PCB looks pretty d*mn clean from here!  If you checked it with a Mantis microscope, too, then bridges are not the issue.
   
  This may sound a bit ridiculous, but are you sure you wired the output connector correctly?  You can sometimes get the symptoms you describe on DACs _or_ amplifiers, if the wires are crossed - ground with signal.  Also, the ground connection is only on the top of the PCB - where the ground plane is.  It looks like you may not have the best soldering on the output leads.  The ground leads, in particular, appear to have not wicked at all to the top of the board.  The holes are plated and that shouldn't be an issue, but I've had it happen on my own DACs - a Bantam and an Alien once.  In my case, they were never cased and the constant flexing because of that worked the solder joints loose.  I had a heck of a time trying to get the ground leads soldered back correctly.
   
  You can check the output connector and wiring by placing your DMM probes on the connector and some part of the ground on the top of the PCB - away from where the ground leads are soldered.  You can try the pads on the bottom (along with the output connector) at the Wima's and V-D resistors for the signal wires.  You should be able to measure zero resistance when checking for continuity.
   
  Anyway, those are some of my guesses for the time being.


----------



## mmcaleer

The problem was the stereo jack.  It was not the correct jack, it was a closed circuit jack.  I swapped it out and it sounds MUCH better now but lacking a LOT of bass. like almost none.  Highs are so high it almost hurts.  Besides that, the sound quality going through the DAC into the CMOY is night and day vs straight out of the computer.  What should I look for to solve the bass issue?
   
  Mike


----------



## akgfan

Isn't that just your initial impression? I was thinking the same at first and searching forum. But no solution worked and then I got used to it. It just sounds so much clearer and have more highs than for example soundcard. However, when songs have deep bass, the bass is there.
   
  Edit: If you are used to EQ or some bass boost function on your soundcard and forgot that you have enabled it, you may be surprised. 
	

	
	
		
		

		
		
	


	




 And you never know how your soundcard manipulates with sound.


----------



## jdkJake

Can you verify the values of C16 and C17?
   
  R8 and R9 look to be correct (110R), but, I cannot see the WIMA caps well enough to verify they are the correct value.


----------



## mmcaleer

Quote: 





akgfan said:


> Isn't that just your initial impression? I was thinking the same at first and searching forum. But no solution worked and then I got used to it. It just sounds so much clearer and have more highs than for example soundcard. However, when songs have deep bass, the bass is there.
> 
> Edit: If you are used to EQ or some bass boost function on your soundcard and forgot that you have enabled it, you may be surprised.
> 
> ...


 

 I was listening to Spotify and the highs were killing me with no bass at all.  When I used iTunes and adjusted the built in equalizer I could bump up the bass and drop the highs to get it sounding better.  I ended up loading Equalify into Spotify, which is an EQ plug for Spotify, and it allowed me to adjust the music to taste.  I still think there is not enough bass and the highs are overpowering IMHO.
   
  Thanks,
   
  Mike


----------



## mmcaleer

Quote: 





jdkjake said:


> Can you verify the values of C16 and C17?
> 
> R8 and R9 look to be correct (110R), but, I cannot see the WIMA caps well enough to verify they are the correct value.


 


  They are the WIMA caps that came in the kit.  .015 63~


----------



## tomb

Quote: 





mmcaleer said:


> I was listening to Spotify and the highs were killing me with no bass at all.  When I used iTunes and adjusted the built in equalizer I could bump up the bass and drop the highs to get it sounding better.  I ended up loading Equalify into Spotify, which is an EQ plug for Spotify, and it allowed me to adjust the music to taste.  I still think there is not enough bass and the highs are overpowering IMHO.
> 
> Thanks,
> 
> Mike


 

 There is definitely something still wrong.  The GrubDAC has excellent, authoritative bass.  How about that wiring to the PCB?  Can you try to solder to the topside some of the exposed wires and pads on the ground leads?  What kind of connector are you using now?  Can you try just some alligator clips to make the connections?


----------



## cobaltmute

Try putting a set of 1K resistors in line with the outputs and drive a set of headphones direct and see how that sounds.


----------



## scootsit

Well, I have come to the conclusion that I have shaky hands. I tried building one of these for the Millet Mosfet Max I've been working on. I started with a SkeletonDAC, and screwed that up, and I just screwed up the grubDAC. I have a really hard time with surface mount stuff. Oh well, maybe one day... Until then, I think I'm going to need to buy a pre-built DAC. Thanks for designing what appears to be an awesome product, guys!


----------



## Avro_Arrow

Have you destroyed the boards or are they salvageable?
  I might be able to fix them up if they are not too badly damaged...
  
  Quote: 





scootsit said:


> Well, I have come to the conclusion that I have shaky hands. I tried building one of these for the Millet Mosfet Max I've been working on. I started with a SkeletonDAC, and screwed that up, and I just screwed up the grubDAC. I have a really hard time with surface mount stuff. Oh well, maybe one day... Until then, I think I'm going to need to buy a pre-built DAC. Thanks for designing what appears to be an awesome product, guys!


----------



## scootsit

The skeleton is pretty screwed up. The grub may be salvagable. I'd be happy to drop it in the mail to ya. PM me your address?


----------



## lehtinel

Started tinkering with my Grubdac after having it put away for a couple of months. Resoldered the chips, tried it once, the Wolfson chip gave some orange light and smoke as I plugged it in. Tried reflowing one more time and VOILA, IT WORKS.
   
  Really, after the chips giving out smoke and light like that I was thought it was screwed. Glad it works! The audio is good!


----------



## tomb

Quote: 





lehtinel said:


> Started tinkering with my Grubdac after having it put away for a couple of months. Resoldered the chips, tried it once, the Wolfson chip gave some orange light and smoke as I plugged it in. Tried reflowing one more time and VOILA, IT WORKS.
> 
> Really, after the chips giving out smoke and light like that I was thought it was screwed. Glad it works! The audio is good!


 

 You're right - that's surprising, but I'm glad you got it working!


----------



## lehtinel

Im really glad too. After losing and burning chips, ordering new ones, having the project put away because of the frustation surrounding it. 
   
  Only goes to prove that this DYI SMD stuff really needs patience. I've now got a clear and crisp setup at work: GrubDAC - 6DJ8 Amp - Sennheiser HD600, makes Mondays less Monday


----------



## TheLaw

Hello,
   
  Does anyone know if I can use 1/8W resistors instead of the 1/4W resistors. I was thinking about using some thin film resistors instead, just for the heck of it, but it seems they only come in 1/8W.
   
  Thanks.


----------



## Insighter

Quote: 





thelaw said:


> Hello,
> 
> Does anyone know if I can use 1/8W resistors instead of the 1/4W resistors. I was thinking about using some thin film resistors instead, just for the heck of it, but it seems they only come in 1/8W.
> 
> Thanks.


 


   
   
  Hi! I think it acceptable.


----------



## DingoSmuggler

Quote: 





thelaw said:


> Hello,
> 
> Does anyone know if I can use 1/8W resistors instead of the 1/4W resistors. I was thinking about using some thin film resistors instead, just for the heck of it, but it seems they only come in 1/8W.
> 
> Thanks.


 
  The only resistors in the signal path are the thru-hole RN50's. Deviating from the BOM for the smd resistors _is not going to yield any benefits whatsoever_, unless you find some purty colourful ones, then the bling factor might increase depending on your tastes.
   
  1206 thin films come in 1/4W, shouldn't be that hard to find, but 1/8W are fine too.
   
  If you're gonna upgrade the SMD resistors for something different, why not go for mini-MELF 0204s?
  These use the same pad size as 1206s, but are tubular, like thru hole resistors. Look for SMM0204s on Mouser or MMA0204s on digikey.
   
  Personally I would (and did) stick to the BOM/kit.


----------



## TheLaw

Okay I suppose I will just stick to the standard thick films. But thanks anyway. MELFs are like impossible to solder...soo...


----------



## cobaltmute

I would agree with the running comment - just stick with the kit resistors.
   
  If you want to do anything fancy, the only thing I would be tempted to look at is non-magnetic, for which you will pay a pretty penny.


----------



## simplethings

First, thanks for a great little DAC - really handy size and a great price. I built a GrubDAC a few months ago and have been very happy with it as my on the road source. It's setup with the on-board miniUSB and I managed to squeeze a mini-jack socket in Hammond enclosure as well making it nice and self contained:
   

   
  I'm considering tweaking as per the GrubDAC Tweaks and swapping out the three polymer caps at C1, C5 & C15 for three Nichicon UKW1A471MEDs (as well as putting three holes in the Hammond box to allow the caps to poke through). Has anyone tried swapping the caps out and if so, was it worth doing (aka would you do it again if you built another ) ?


----------



## particleman14

I've used those caps before but only because the polymers were sold out one time..  I don't notice any difference other than the nichicons won't fit into the small hammond box without some reworking..  why would you want the caps sticking out of that neat enclosure?


----------



## simplethings

If the noise reduction was audible I'd happily have 3 caps sticking out of the top. If the difference is negligible well, there is no reason to ruin a poor little hammond box. What I'll perhaps do, as there hasn't been much response on this topic, is given the GrubDAC some good listening over the next month, swap the caps and report back.


----------



## DingoSmuggler

Quote: 





simplethings said:


> If the noise reduction was audible I'd happily have 3 caps sticking out of the top. If the difference is negligible well, there is no reason to ruin a poor little hammond box. What I'll perhaps do, as there hasn't been much response on this topic, is given the GrubDAC some good listening over the next month, swap the caps and report back.


 

 The noise-floor on my grubDAC is not noticeable.
  You could always fit the standard caps, and retro-fit the larger electrolytics later if you're not happy.


----------



## cobaltmute

Quote: 





simplethings said:


> If the noise reduction was audible I'd happily have 3 caps sticking out of the top. If the difference is negligible well, there is no reason to ruin a poor little hammond box. What I'll perhaps do, as there hasn't been much response on this topic, is given the GrubDAC some good listening over the next month, swap the caps and report back.


 

 You shouldn't hear much (if any) of a difference.  This is one of those tweaks, that at an absolute level will do something, but may not make an audible difference.


----------



## TheLaw

Hey guys,
   
  Just finished building my GrubDAC and it works. Good sound...However I have one issue. I think that has to do with my computer but I just want to see if anyone knows how to do this?
   
  I want to be able to control system volume via the slider on the bottom of the taskbar. I'm running Windows 7 64-bit. Currently moving the slider does nothing. I can only change the volume if I right click and go to mixer and change each individual programs audio, but I want to be able to change all of them at once, like I am familiar with. Also, hitting mute doesn't do jack sh--t.
   
  I know you might tell me that I should not be using windows for volume control, however, this is a shared computer and I have to have it this way.
   
  Any ideas on how to configure it?


----------



## tomb

Quote: 





thelaw said:


> Hey guys,
> 
> Just finished building my GrubDAC and it works. Good sound...However I have one issue. I think that has to do with my computer but I just want to see if anyone knows how to do this?
> 
> ...


 

 Well, I'm hoping cobaltmute will respond to this, if he has time.
   
  However, you know what we're going to tell you - adjusting the volume control through the OS on a PC actually reduces the bits in the music stream.  I'm not sure I understand your situation with a "shared" computer.  Maybe you need to load a player that will identify a separate sound source such as Foobar.  That way, it doesn't matter what the OS is using as the sound card - you can select the GrubDAC independently.
   
  In any event, if you have a "shared" computer, it doesn't seem to me a very considerate situation to have your GrubDAC assume the default soundcard status of the OS.  Chances are, that's what's getting mixed up in the volume control, because you shouldn't have to go in and adjust the mixer.
   
  Maybe you could tell us more about your situation and we could suggest a better work-around?


----------



## TheLaw

Well I'm on a computer that is shared amongst people in my household. So I can't just suddenly have the volume slider not work...
   
  The problem confuses me a lot because traditionally the volume bar with control all of the programs volume at once. In the mixer you can set each individual program to have lower or higher volume limits. However, in my case, I have all of the applications set to maximum volume as well as the main volume slider. You would assume moving the bar up and down would proportionally reduce or lower the volumes of all applications, however, sliding the volume bar does nothing! Sure, I can control volume, but _only _if I go into the mixer and change each individual program. I disconnected the DAC and switched back to onboard sound. Now the volume slider works fine.
   
  So if I move the main slider to volume 5, it will be the same volume even if I move it to volume 50.
   
  Graphically, the volume slider works fine. The animations it shows with the graphic visualizer (VU meters) correspond with the change in volume, but the sound does not.
   
  Does not anyone else have this problem? I really find that hard to believe...
   
  Thanks.


----------



## tomb

Quote: 





thelaw said:


> Well I'm on a computer that is shared amongst people in my household. So I can't just suddenly have the volume slider not work...
> 
> The problem confuses me a lot because traditionally the volume bar with control all of the programs volume at once. In the mixer you can set each individual program to have lower or higher volume limits. However, in my case, I have all of the applications set to maximum volume as well as the main volume slider. You would assume moving the bar up and down would proportionally reduce or lower the volumes of all applications, however, sliding the volume bar does nothing! Sure, I can control volume, but _only _if I go into the mixer and change each individual program. I disconnected the DAC and switched back to onboard sound. Now the volume slider works fine.
> 
> ...


 

 I've got Windows 7 - although I'm not running 64-bit (unfortunately).  However, it does the same thing with me.  Netflix runs in Internet Explorer and a Netlfix movie is not affected by anything but the separate mixer for "Internet Explorer."  Likewise, if I play music with the Windows Media Player, the only thing that controls the volume is the Windows Media Player volume in the mixer.
   
  It appears that Windows 7 recognizes another property under the sound controls - that of default "Communication Device."  If you change one playback source to another, the default "Communication Device" may remain with the disabled sound device.  I tried changing that, too, to the GrubDAC and it had no effect on the overall volume slider issue.
   
  IMHO, this appears to be a quirk with Microsoft "improvements" that were incorporated in Windows 7.  (I once called one of their updates the worst virus I ever experienced.)  I seriously suspect that you're going to get this phenomenon with many DACs. After all, the PCM2706/7 is fairly ubiquitous as a USB interface, not just with the GrubDAC.  I guess more accurately, one should state that TI's PCM2706/7 has not caught up fully with the new features in Windows 7.  'Course, the way this usually works is that Microsoft sits back and waits for the mfrs to pay them up front for insight into the latest OS.  If not, then the rest of us suffer for several years with drivers that are a bit buggy until they get re-written.  I still have a PC running Windows XP because it's the only thing compatible with my M-Audio Transit.
   
  You still didn't mention what you're trying to access, but honestly, the Foobar solution is ideal and I've never had an issue.  The Netflix volume control and the Windows Media volume control all work independently and operate just fine with the GrubDAC as the default device.  However, the volume control to my DVD interface (CybeLlink Power DVD) does not work independently.  So granted, it's inconsistent.
   
  Still, all you have to do is select "mixer" and one of the controls will always work.  All you need do is to remember to set it back when you leave, right?  Actually, you don't even have to do that, because the volume control for the device you were using will disappear when it's not running.
   
  Not sure that fully answers your question, but it's the best I can do at the moment.


----------



## Avro_Arrow

Windows 7 volume control behaves differently to previous versions.
  PCM270x have been redesigned as a result. See here:
  http://www.ti.com/lit/an/sbfa019/sbfa019.pdf
   
  It might not have anything to do with your problem, but then it might...


----------



## TheLaw

So can it would be a pain in the dupa, but can I solder on a PCM2706_C_?


----------



## tomb

Quote: 





avro_arrow said:


> Windows 7 volume control behaves differently to previous versions.
> PCM270x have been redesigned as a result. See here:
> http://www.ti.com/lit/an/sbfa019/sbfa019.pdf
> 
> It might not have anything to do with your problem, but then it might...


 
  No, that's a good catch - it has everything to do with the problem.

 Unfortunately, the "C" version of the PCM2706/7 is still in "Preview" mode, only, at TI.  ("PREVIEW: Device, tool, or software has been announced *but is not in production*. Samples may or may not be available.")  That means it can't be ordered in volume at Mouser/DigiKey and we can't put it in GrubDAC kits.
   
  Quote: 





thelaw said:


> So can it would be a pain in the dupa, but can I solder on a PCM2706_C_?


 
   
  See the above.  You can try to get a sample from TI.  (This is certainly a legitimate use of the sample program!)  Let us know how it works out.  I'll try to do the same when I get a chance.
   
  Isn't Microsoft wonderful?


----------



## TheLaw

Ugh...Now I kind of don't like W7 anymore. Damnit. Colbaltmute, I think you should add that to the GrubDAC page: that it may not work too well in W7. It will work...just not as  you might expect.
   
  Hmm....replacing that PCM might be a pain in the arse since everything's already in place and I dont have hot air rework.
   
  Plus TI might not be nice. Grr.


----------



## tomb

Quote: 





thelaw said:


> Ugh...Now I kind of don't like W7 anymore. Damnit. Colbaltmute, I think you should add that to the GrubDAC page: that it may not work too well in W7. It will work...just not as  you might expect.
> 
> Hmm....replacing that PCM might be a pain in the arse since everything's already in place and I dont have hot air rework.
> 
> Plus TI might not be nice. Grr.


 

 It doesn't matter - samples aren't even available: "Contact your distributor."  That typically means very long lead times and high quantities required.
   
  I wouldn't blame TI, though, at least they're trying to respond to the change.  It's Microsoft that did it.  Seems to me _any_ USB device with sound will be similarly affected.


----------



## TheLaw

Oh I'm not blaming TI. Even though TI has huge market share...whether they got there fairly or not...I don't know, I like them.
   
  Just wanted to comment on the actual GrubDAC. I'm using this hooked up to a homemade power chipamp. About 50Wx2 + 50Wx1 (sub). Bass is so much more punchy. I can't really believe it. I wouldn't say I'm stunned by new things in the music popping out at me, but it is much cleaner sounding than the onboard sound, which is decent to start with. So a bass drum actually feels/sounds like a real bass drum hit. I'm not going to use the fancy words I see some of you guys use...but it really does sound better.


----------



## tomb

Quote: 





thelaw said:


> Oh I'm not blaming TI. Even though TI has huge market share...whether they got there fairly or not...I don't know, I like them.
> 
> Just wanted to comment on the actual GrubDAC. I'm using this hooked up to a homemade power chipamp. About 50Wx2 + 50Wx1 (sub). Bass is so much more punchy. I can't really believe it. I wouldn't say I'm stunned by new things in the music popping out at me, but it is much cleaner sounding than the onboard sound, which is decent to start with. So a bass drum actually feels/sounds like a real bass drum hit. I'm not going to use the fancy words I see some of you guys use...but it really does sound better.


 

 We don't use those fancy words in the DIY section, either.
	

	
	
		
		

		
			





  Many thanks for the kind comments on the grubDAC!  Cobaltmute did a great job bringing it to us and there's more coming!


----------



## scootsit

I've been listening to my iPod through my Millet Mosfet Max. I popped my grubDAC in and...HOLY CRAP! What a difference! This thing is AMAZING!


----------



## funch

Quote: 





tomb said:


> Cobaltmute did a great job bringing it to us and there's more coming!


 


   Do tell!


----------



## tomb

Quote: 





funch said:


> Do tell!


 


http://www.head-fi.org/t/385013/my-dac-design-pup1-dac/210#post_8202700


----------



## funch

Neat, thanks! I'm subscribing to that one.


----------



## scootsit

I'm curious, where do you guys come up with the names for these DACs?


----------



## tomb

Quote: 





scootsit said:


> I'm curious, where do you guys come up with the names for these DACs?


 

 Cobaltmute comes up with them all by his lonesome.


----------



## cobaltmute

scootsit said:


> I'm curious, where do you guys come up with the names for these DACs?




When I did my first design, I was looking for something to name it after. I decided to use the name of animals. The design was the cub1, which never got past the design phase. That was revised into the pup1 - which we now call the pupDAC. The grubDAC was named after the idea of something small, like an insect (as it was smaller than pup design). The SkeletonDAC is a word pun based upon the fact that it started as a "bare-bones" design. I couldn't think of anything insightful for the r1 - it just means "regulator 1"


----------



## scootsit

I really love the grubDAC, but would love the ability to add digital coax or optical inputs. Is there any plan in the future for a DAC with multiple inputs?


----------



## Avro_Arrow

AMB and Twisted Pear both offer DACs with various inputs
   
  Or are you waiting for Cobaltmute to design one...


----------



## scootsit

Just curious if there was ever a plan to do so.


----------



## korben69

Quote: 





avro_arrow said:


> AMB and Twisted Pear both offer DACs with various inputs
> 
> Or are you waiting for Cobaltmute to design one...


 
   
  Yes, it's really a pretty good idea, multiple inputs


----------



## tomb

EDIT: never mind (what I posted before) - getting DACs mixed up.
   
  I'm not sure you guys would seriously consider that there's room on a grubDAC PCB to provide additional input types.


----------



## cobaltmute

I need to finish the revised pupDAC first. After that you never know what might come next.


----------



## geofftnz

Tried to build my GrubDAC last night, but had a unseen bridge on U1 that shorted VDD to ground. (LED lit but flickering, 10mV on 3.3V test point, no USB detection, one very hot inductor). Fixed that, but now it's doing the "USB device unrecognised" thing. I'll give it another once-over tonight to see if reflowing will help, but have ordered another kit just in case. (Hey, even if I fix the first one I'll have an extra DAC - can't have too many grubs)
   
  Current DAC kit deathmatch score: 2/3.


----------



## korben69

Hi all
   
  I'm wondering about C15-16-17 caps to complete a GrubDAC.
  For C16-C17 values, I've got Wima's in 10nF, what's your opinion vs 15nF ?
  For C15 value, will a 330uF Oscon Polymer low esr do the job ?
  In this position, recommended part value is within 220 and 560uF.
  Cheers


----------



## cobaltmute

C15 should be fine.

C16-17, you will change the corner frequency of the filter a bit. I'm thinking you still should be ok.


----------



## korben69

Thank you for the answers Cobaltmute.
  Could you point me where I can find some explanations about the corner frequency ?
  As noticed on the scheme, C16-17 caps seem to be output caps, between each LineOut(R/L) and Gnd.
  On GrubDAC page's we are told : no need for output caps... So, can we deal without using them ?
  I've noticed C16-17 could be populated with SMD parts. Have you some prefered refs ?
  Confusing to me, sorry for my weak knowledge.
   
  I've commited most of your projects, waiting for pup1 launch !
  Cheers


----------



## cobaltmute

R8 + C16 for one channel and R9 + C17 for the other channel each are low pass filters. They perform the function of removing some high frequency noise that is generated by the D-to-A process. This compares to a DC blocking output cap which is in line with the signal (you can check C13/14 on the SkeletonDAC schematic for a comparison)

I have this filter calculator bookmarked: http://www.muzique.com/schem/filter.htm There are likely others that work just as well.

As for SMT versus through-hole for those parts, I think the TH hole parts may sound better, but I have never done a blind listening comparison to hear if there is any differences. The SMT part choice is present as that was the only choice on the original grubDAC prototypes.


----------



## beerguy0

Just ordered the GrubDAC kit. Should be a pretty easy build.


----------



## Lil' Knight

Just finished populating another Grub... Everything seems to be fine; device recognized by Windows, LED lit up, voltages read 5.15v and 3.26v respectively but sound coming out along with noise on both channels. It does sound like something wrong with the grounding. I did check the output wiring, no short anywhere.

Any idea where I should check?


----------



## Avro_Arrow

Close-ups?
   
  May be a problem in the I2S lines...
  
  Quote: 





lil' knight said:


> Just finished populating another Grub... Everything seems to be fine; device recognized by Windows, LED lit up, voltages read 5.15v and 3.26v respectively but sound coming out along with noise on both channels. It does sound like something wrong with the grounding. I did check the output wiring, no short anywhere.
> Any idea where I should check?


----------



## Lil' Knight

Best I can take...


----------



## tomb

Actually, it looks like your output leads' soldering may be a bit dodgy.  One of those OG leads looks like it's beginning to come loose, even.  Check that and the wiring to your connector, whatever that is.  If those ground wires are not soldered in well, or the leads to the connector are loose, you could get a lot of noise in the output.  Problems with the ground connections are not necessarily going to show up as a short.


----------



## Avro_Arrow

OL has a cold solder joint and the Wolfson DAC has some solder bridges.
  Pins 9/10 look to have a bridge. Needs to be re-flowed.
  Pins 15/16 have a solder ball sitting between them, you should be able
  to brush that away with a toothbrush or a needle.
   
  If you have some form of magnifying glass (I use an old camera lens)
  check between and behind the IC pins for hidden solder bridges.


----------



## Lil' Knight

Turned out nothing wrong with the Grub, I messed up with the setting in foobar2000... *facepalm* Making sound like it should now.


----------



## tomb

Quote: 





lil' knight said:


> Turned out nothing wrong with the Grub, I messed up with the setting in foobar2000... *facepalm* Making sound like it should now.


 

 Well, then - sorry that we criticized your soldering.


----------



## Avro_Arrow

Maybe we should do a facepalm...but it is sometimes hard to tell in pictures.
  The output connections do have cold solder joints even if they were not the problem.


----------



## Lil' Knight

Yes, I did reflow the joints and it sounds 150% better now.


----------



## beerguy0

Finished my GrubDAC yesterday (built in in a couple of lunch breaks on my bench at work, where I have proper tools, magnification, etc.). Did a basic test at work (everything worked fine), and brought it home last night. Fired up the laptop and was able to access my music files on my desktop PC. Piped through my recently completed MiniMAX, the sound was excellent. (Lossless flac --> laptop --> GrubDAC --> MiniMAX --> Denon AH-D5000)
   
  So far, I am very impressed with the GrubDAC. The music was presented very cleanly, with good soundstage and imaging. Bass was solid, and highs were clear and sparkling without being shrill or harsh. I think it sounds better than my iMod, based on a fairly short listen. I'll do some more listening and get some burn-in time on the DAC. I will likely use my iMod as my main work/portable source and use the DAC at home.


----------



## tomb

Quote: 





beerguy0 said:


> Finished my GrubDAC yesterday (built in in a couple of lunch breaks on my bench at work, where I have proper tools, magnification, etc.). Did a basic test at work (everything worked fine), and brought it home last night. Fired up the laptop and was able to access my music files on my desktop PC. Piped through my recently completed MiniMAX, the sound was excellent. (Lossless flac --> laptop --> GrubDAC --> MiniMAX --> Denon AH-D5000)
> 
> So far, I am very impressed with the GrubDAC. The music was presented very cleanly, with good soundstage and imaging. Bass was solid, and highs were clear and sparkling without being shrill or harsh. I think it sounds better than my iMod, based on a fairly short listen. I'll do some more listening and get some burn-in time on the DAC. I will likely use my iMod as my main work/portable source and use the DAC at home.


 
  Fantastic!  Glad it went well.


----------



## Chet_Summers

Just finished my GrubDAC build (cableDAC config).  Found out that I'm not all that great at surface mount soldering but still somehow got the DAC working.  Used lots of solder wick to clean up the messes I kept making.
   

  Went with rubber grommet and a regular black case. 

  Many thanks to TomB and cobaltmute for all the work that went into the design and putting the kits out.


----------



## Nomnomnom

This seems to be the main GrubDAC thread so I'll post my woes here. I recently finished a Millet Mosfet Max build thanks to the help of a few Head-fi members/mentors (check this thread out if you're having any issues: http://www.head-fi.org/t/604880/having-an-issue-with-a-mosfet-max-build). In addition to this, my third or fourth endeavour into DIY audio, I started a GrubDAC build. Despite the fact that I've never delved into SMD before I feel that the end result is halfway decent.... looking...
      My issue is this: 1) Both of my computers recognize the DAC as "USB audio DAC" or something to that effect. 2) The LED lights up as it should. 3) The only way I've tested this so far is to plug it into the punch down block inputs of the MAX and see what happens. I also tried threading the outputs of the DAC into the extra pot pads with the same result. Humming... No music just a humming noise from my headphones.
      I have a few pics that I hope will help you guys help me and I can take plenty more if needed. As I stated in my mosfet max build thread, I'm not an electrical engineer but I'm pretty good at problem solving/understanding things as long as it's in laymans terms. Without further ranting and getting to the point, here's some pics and thanks in advance for any help given:


----------



## geofftnz

Nice photos!
   

 Is that a solder bridge on the top left of U1?
 One of the mini-USB pins looks like it might be a cold joint.
 I'd also check the right hand side of the top row of DAC pins in case there's stuff in there causing problems.
   
  I hope you get it going - I destroyed one on my first attempt, but the second one works a treat.


----------



## Nomnomnom

Reflowed all mini-USB pins, cleaned, checked - no go
   
  Cleaned all extraneous stuff between all pins (was Q-tip fuzzies from prior cleaning lol), checked - no go
   
  Tried desoldering possible solder bridge between pins 1 & 2 on the left row top side, solder refused to lift no matter the amount of flux or patience applied so VERY CAREFULLY took an X-Acto knife and scratched the bridge away....
   
  Thank you Geofftnz, this freaking little bridge has been p-ing me off and holding me up from ordering the remainder of items necessary to case up my Millet MOSFET Max build that a few other Head-Fier extraordinaires coached me through. I actually have half a mind to order another one just cause that little sctratch in the PCB is gonna get to me even though I can't see it lol.
   
  Sounds awesome so far by the way, I've been running through a uDac2 as my source until now and I can't say it's a slouch, it's a very "fun" DAC but I"m going to spend some time switching between the two this weekend and taking (objective) notes to post up on here.
   
  Thanks again, I'm a little peeved that I missed that but I'm glad you picked up on it.
   
  -Chris


----------



## geofftnz

No worries... a fresh set of eyes always helps!


----------



## Nomnomnom

Oh and thank you for the compliment on the pics. Just FYI for all the readers my photo setup is nothing more than a point and shoot digital cam (Sony DSC-H3) on a baby tripod in macro mode. I held an LED flashlight behind the GrubDAC to emphasize the soldering, put the camera on a 10 second timer, focused and shot. Just a hint: In macro mode, keep the object close, don't place it at a distance and attempt to zoom because the camera will not focus....


----------



## Mullet

Finished off my first GrubDAC. Started up just fine. It was a fairly easy build with the exception of dealing with smd caps and resistors that didn't want to stay stiill. I went with the Hammond 1455C801 case and scored some Front Panel Express files from Beftus, which I then slightly modified to my liking. I then air wired the led and 1/8" jack. The trick to getting the board to stay stationary was to buy some perf board at the good old RatShack, which I then scored with an exacto knife to match the needed size. I then broke the piece off and sanded the edges to get a perfect fit. Here are a few pics...
   
  As far as the sound quality, I'd say this DAC is on par with a Gamma-1. They seem to have similar presentation and a lively feel. For the money, even with spendy FPE panels, you can't go wrong.


----------



## geofftnz

Quote: 





mullet said:


> The trick to getting the board to stay stationary was to buy some perf board at the good old RatShack, which I then scored with an exacto knife to match the needed size. I then broke the piece off and sanded the edges to get a perfect fit.


 
   
  Looks nice! Are you using the perfboard to adapt the grubdac board to slots in the case?


----------



## Mullet

Yup. That's exactly what I did. It's the best way to do it other than using something like these... http://bit.ly/LlR57A


----------



## geofftnz

Yeah, I've just done a grubdac+PIMETA2 build in a slightly large Hammond case. I used 10mm hex spacers to mount the boards, however without a high-speed drillpress it's very hard to drill the holes exactly where you need them, even when using a centre-punch. Consequently the amp board has only 2 screws.
   
  Next time I'll use your perfboard trick.


----------



## Mullet

Those stand-offs I linked to have adhesive on the bottom. I'd imagine if they were too big you snip some of the plastic off to make it fit in that Hammond case.
   
  I don't have a high-speed drillpress at my disposal and I'm about to embark on a journey building both "The Wire" and an EHHA Rev A not long after. I'm nervous about drilling the proper holes without the right tools, so I think those self-adhesive stand-offs are going to be clutch.


----------



## Beftus

Quote: 





mullet said:


> I went with the Hammond 1455C801 case and scored some Front Panel Express files from Beftus, which I then slightly modified to my liking.


 
   
  Looking good Mullett!


----------



## athanor1723

Is it possible to make a grubDAC minus the 2706 and feed an i2s signal directly to the WM8524? Would I just leave off parts of the build, or would it require a redesign?  Also, would i2s off a small ARM computer be a sonic problem, or would it be fine since it's still digital at that point?


----------



## cobaltmute

athanor1723 said:


> Is it possible to make a grubDAC minus the 2706 and feed an i2s signal directly to the WM8524? Would I just leave off parts of the build, or would it require a redesign?  Also, would i2s off a small ARM computer be a sonic problem, or would it be fine since it's still digital at that point?




It could be possible. You'd need to feed 5V power to the board and then solder wires to the appropriate pads.

Not something I would want to do, but it is possible.


----------



## lehtinel

A small problem I've encountered: Since last weekend, the GrubDAC that I use at work doens't show up on my Mac at startup. When i put on some music it comes out through the built in speakers (very annoying). I have to disconnect the USB cable from the Grub and put it back - everything works as it should.
   
  Any ideas on what could be wrong?
   
  Been using it for three - four months now, been working flawlessly until now.


----------



## scootsit

Quote: 





lehtinel said:


> A small problem I've encountered: Since last weekend, the GrubDAC that I use at work doens't show up on my Mac at startup. When i put on some music it comes out through the built in speakers (very annoying). I have to disconnect the USB cable from the Grub and put it back - everything works as it should.
> 
> Any ideas on what could be wrong?
> 
> Been using it for three - four months now, been working flawlessly until now.


 

 It sounds silly and really intuitive, but I have found that to happen if the plug isn't seated very well. USB makes the ground connection first, followed by power, then signal. I have found that the plug sits in the jack very well with just power and ground connected (so the LED lights) but loose enough that there is no signal. In short, see if instead of unplugging and replugging, just pushing the plug in further helps.


----------



## hitman47

Man, I can't believe this. I've already botched 2 GrubDAC PCB's and successfully finished one and now I'm making one for a friend and who would have known it, it doesn't work. When I plug it in (it's a cableDAC btw) the LED flickers and nothing works, although I got it to get recognized by the PC before (I had the LED mounted the wrong way, so I don't know how it looked but I'm assuming it would have lit up normally) and it even played some music twice (which would indicate that not all hope is lost?). It quickly stopped working though and I tried reflowing all the pins of the DAC chips, and I replaced the VRM twice, to no avail. The 3.3V measuring point gives me 0.2-0.4V, resistance from 3.3V to ground is around 0. At this point I'm thinking there's a short in U1 caused by excessive soldering heat since I've had the exact same problem before and that turned out to be the issue, plus I find it difficult to believe that I managed to kill 3 VRMs with my crappy soldering skills. I'm just looking for some confirmation before I submit the order for a new PCM chip (which is absolutely pants-on-head stupid since I only today received a Farnell order with replacement VRMs among other things, now I'll have to shell out another $15 for shipping). Here's some pics for good measure, although I've already triple-checked for solder bridges (there is one, but it's between the AGNDL and ZGND pins which are connected anyway) and bad joints.
   
  Edit: Am I correct in assuming that the only way to figure out whether U1 has an internal short would be to remove U1 and then see whether the LED still flickers/the 3.3V supply is up? Or would the LED not be lit at all if the short was in U2?


----------



## vixr

Quote: 





scootsit said:


> It sounds silly and really intuitive, but I have found that to happen if the plug isn't seated very well. USB makes the ground connection first, followed by power, then signal. I have found that the plug sits in the jack very well with just power and ground connected (so the LED lights) but loose enough that there is no signal. In short, see if instead of unplugging and replugging, just pushing the plug in further helps.


 
  I see the same thing with the USB cable I use to download video from a DVR...finally had to build a new cable.


----------



## Avro_Arrow

Remove L3. If the regulator returns to normal, check for solder bridges under the bypass caps connected to the 3.3 volt line.
  Namely C2, 4, 6, 10 and 11.
   
  The LED just indicates that you have power coming from the computer.


----------



## hitman47

Quote: 





avro_arrow said:


> Remove L3. If the regulator returns to normal, check for solder bridges under the bypass caps connected to the 3.3 volt line.
> Namely C2, 4, 6, 10 and 11.
> 
> The LED just indicates that you have power coming from the computer.


 
  Removing L3 fixes the short, however I couldn't find any bridges under the capacitors, I desoldered and re-soldered them all and it didn't fix the issue. Either one of the caps is burnt and shorts the 3.3V line (is that possible/probable with those ceramic caps? I would have thought they should be quite heat resistant) or it's U1. U1 also gets pretty warm after a while of leaving it on, which I guess points toward an internal short too.


----------



## Avro_Arrow

That is probably the next step...remove U1.
  Once it is out, check the power and make sure it
  is good before soldering in a new U1.
   
  If you pull U1 and the voltage is still bad, 
  then you might have to take a closer look at U3.
   
  You can check the ceramic caps for short with your meter
  while they are removed from the board.


----------



## hitman47

I did as you suggested, and the short seems to be within U1, without it power works fine and U2 doesn't get as hot anymore either. I'll order a new U1, I sure hope I don't break it this time (maybe I should order 2, lol). These chips seem to be really sensitive to heat/ESD, this is the second time this has happened to me.


----------



## Lyel

I (finally) finished my first GrubDAC build, and I am extremely happy with it.  This is a great entry into an improved DAC (from my laptop sound card, anyway) as well as a good way to start into SMD work.  I swear I've never heard my music library before - it's made that much of a difference for me.  Thanks Cobaltmute for the great design, and to TomB for the kits!
   
  I experienced one issue as I was constructing mine, and I thought I'd record it here in case someone else runs into the same issue.  After getting the board populated and the RCA and USB cables attached, I was getting the "USB device not recognized" under Windows 7, usually followed by "Device driver failed to install correctly."  I followed the advice in some of the other GrubDAC threads, checking and double-checking my soldering on U1 and U3, primarily.  After much time spent reflowing those chips and carefully determining that I had no bridges or bad joints, I moved on to reflowing the other components.  Finally, I redid the soldering on X1, and bingo - it did the trick!  I was concerned that I had somehow damaged U1, but no, I just had not done a good enough job with the oscillator.  Everything is working like a charm now, and sounding fantastic.


----------



## cobaltmute

The thing about X1, which is a little different that a lot of other components that you will solder down, is that you can create a bridge to the top of the part. It appears that the top case of the part is connected to ground, so any solder that gets up the sides and touches the ground will create a short.

Nice to hear that you are enjoying it.


----------



## Pingupenguins

Just built my grubDAC with my new (but used) Hakko 936. Worked the first time without incident! My only beef is that the Hammond case is too thick and I can't get the Mini USB very close to the outside. Thus my USB connection is finicky. :/
   
  I'm probably going to wire a grubDAC to a cMoy if I get fed up with the Hammond case.


----------



## tomb

Quote: 





pingupenguins said:


> Just built my grubDAC with my new (but used) Hakko 936. Worked the first time without incident! My only beef is that the Hammond case is too thick and I can't get the Mini USB very close to the outside. Thus my USB connection is finicky. :/
> 
> I'm probably going to wire a grubDAC to a cMoy if I get fed up with the Hammond case.


 
   
  I think you pretty much have to cut a rectangular slot equal to the plastic housing around the metal portion of the USB connector.  This can vary somewhat, depending on the cable you're using.  However, it's the connector housing that's key - not the metal connector itself.  That's what I've done in the past and it works well.


----------



## Pingupenguins

Quote: 





tomb said:


> I think you pretty much have to cut a rectangular slot equal to the plastic housing around the metal portion of the USB connector.  This can vary somewhat, depending on the cable you're using.  However, it's the connector housing that's key - not the metal connector itself.  That's what I've done in the past and it works well.


 
   
  Yeah, I was thinking that too, but it seems like too much work for now. I just did my first SMD soldering!! Maybe later...


----------



## kamikaxe

I just soldered the GrubDAC and having some problems with voltages. The regulator gets very hot immediately when connecting USB. The 3,3V test point does not show any voltage, it seems to be connected to ground (checked with voltage meter). USB supplies 4,9V and voltage at led is 3,3V. Where to start sort this out?


----------



## tomb

Quote: 





kamikaxe said:


> I just soldered the GrubDAC and having some problems with voltages. The regulator gets very hot immediately when connecting USB. The 3,3V test point does not show any voltage, it seems to be connected to ground (checked with voltage meter). USB supplies 4,9V and voltage at led is 3,3V. Where to start sort this out?


 
  Post some detailed pics.  You've got a bridge/short somewhere - could be in the PCM pins or the regulator itself or something else.
   
  Votage of 3.3V at the LED is not good, because it pulls it's voltage almost directly from the USB connection.


----------



## kamikaxe

Here's some crappy pics, best I can take. I've been looking for short but no results yet
   
  https://lh5.googleusercontent.com/-X4zneoTqduU/UJaOPBQKWGI/AAAAAAAAFIc/j-H-4vNklc4/s639/1.JPG
  https://lh5.googleusercontent.com/-6QxtKXyGDgI/UJaOSXot04I/AAAAAAAAFJc/p9bJ8tnYAdA/s903/IMG_1549.JPG
  https://lh3.googleusercontent.com/-HoIcwLJzi38/UJaOTEY8FkI/AAAAAAAAFJY/xvTmfrmNrmA/s903/IMG_1548.JPG
  https://lh6.googleusercontent.com/-tqiXYpf7prY/UJaOUSRaWcI/AAAAAAAAFJU/lqt6Ik5P6Rk/s903/IMG_1547.JPG
  https://lh6.googleusercontent.com/--nNvHh5QwaM/UJaOVSWSu7I/AAAAAAAAFJQ/81RZZl-qx8s/s903/IMG_1546.JPG
  https://lh3.googleusercontent.com/-A20JOki6sM8/UJaOWoZ-psI/AAAAAAAAFJE/SKo7BLeIHMo/s903/IMG_1542.JPG
  https://lh3.googleusercontent.com/-XiENa5oHnJU/UJaOh_MlhqI/AAAAAAAAFJM/gH4pS4YoYfk/s903/IMG_1544.JPG


----------



## tomb

1. It appears the first photo shows two pins bridged in the middle of the left side PCM2706/7.  As best I can tell, none of the pins on that side should be bridged.
  2. Any one of those electrolytic caps could be shorting out parts.  Yes, they have a plastic wrap and a rubber plug on the bottom, but if the wrap is not completely covering the bottom edge of the can, you can get a short.  If you are going to attempt caps that obviously do not fit, you'd be better off taking them out, soldering new leads on the caps (since the existing have already been trimmed), and bending them over at a right angle.  Hanging them off the edge of the board in a horizontal position would be safest.
  3. Your fourth pic looked pretty bad for the regulator, but the fifth pic seems to confirm that it's OK.  Still, it would be helpful if you went ahead and cleaned the PCB of the residual flux and then took some pics again.
   
  I think that bridge on the PCM chip looks the most suspicious, though.  Get some caps of the right size when you can.


----------



## kamikaxe

I separated the PCM two pins and now windows recognizes the device. The regulator also stays cool now. But there's not coming any sound out, and the voltage at the led is still 3,3v


----------



## tomb

Quote: 





kamikaxe said:


> I separated the PCM two pins and now windows recognizes the device. The regulator also stays cool now. But there's not coming any sound out, and the voltage at the led is still 3,3v


 
  What do you have connected at the output?  None of your pics show anything.
   
  What exactly are you measuring to get 3.3V at the LED?


----------



## kamikaxe

I soldered the RCA's to make some test. Cables and sound device of the PC are triple checked.
  Maybe I just have to start look the smallest pins again if there is some short left.
  The 3,3V at the led is measured between led legs. Is this right?


----------



## tomb

Quote: 





kamikaxe said:


> I soldered the RCA's to make some test. Cables and sound device of the PC are triple checked.
> Maybe I just have to start look the smallest pins again if there is some short left.
> The 3,3V at the led is measured between led legs. Is this right?


 
  Yes, that's true.  I agree with your guess, too - there's still a short somewhere.


----------



## tomb

BTW, if you take another look at this thread, I'd advise you to remove those large caps for the time being.  I don't think it will hurt anything and it will let you and everyone else get a better look at the PCB.


----------



## cobaltmute

kamikaxe said:


> The 3,3V at the led is measured between led legs. Is this right?




You are indirectly measuring the voltage drop of the LED by measuring the legs of the LED.


----------



## tomb

Oops - cobaltmute is exactly correct.  3.3V is only a partial voltage drop in the full path between USB power and Ground.  There's the R5 resistor, which actually sets the current (more or less) for the path to ground.  So, the full voltage drop of the USB 5V would be the voltage drop across the R5 resistor plus the LED.


----------



## daves440

I was wondering if any one has a suggestion on what might have happened and what to try and replace on my grub dac, I disconnected the rca's from one of my amps and connected to a different amp. Both amps where on and usb connected to the computer. One channel is now not working when I switch over. I have to say I learned now not to do this with the equipment on, this is the second time I have done this scenario, the first was with my Bantam dac, I did the same thing and the same outcome, one channel out . Now I have two that I would like to repair but I do not know how to trouble shoot.Can someone suggest what and how to check or what to try to replace?


----------



## tomb

Quote: 





daves440 said:


> I was wondering if any one has a suggestion on what might have happened and what to try and replace on my grub dac, I disconnected the rca's from one of my amps and connected to a different amp. Both amps where on and usb connected to the computer. One channel is now not working when I switch over. I have to say I learned now not to do this with the equipment on, this is the second time I have done this scenario, the first was with my Bantam dac, I did the same thing and the same outcome, one channel out . Now I have two that I would like to repair but I do not know how to trouble shoot.Can someone suggest what and how to check or what to try to replace?


 
  Let me guess - was one of the amps the Starving Student?
   
  Regardless, given your description of the symptoms - replace the DAC chip.  Luckily, that's not such a big deal on the grubDAC. 
	

	
	
		
		

		
		
	


	




  The Wolfson chip is almost the same as de-soldering soldering an SOIC-8 opamp.  Plus, it's very cheap.  On the Bantam, though, you might as well just build another.


----------



## daves440

Thanks Tom, I will order one and replace it, do you know what number to get for the Wolfson dac chip?  I have ordered the Pup Dac, but still will like to get the Grub dac working again. It was disconnected from an old Marantz 2235 and connected to a lepai, some time between this it happened. I never had a problem with my NAD surround.  I guess it is the disconnecting and re connecting of the amps that are on instead of turning them off?
  Thanks


----------



## scootsit

Quote: 





daves440 said:


> Thanks Tom, I will order one and replace it, do you know what number to get for the Wolfson dac chip?  I have ordered the Pup Dac, but still will like to get the Grub dac working again. It was disconnected from an old Marantz 2235 and connected to a lepai, some time between this it happened. I never had a problem with my NAD surround.  I guess it is the disconnecting and re connecting of the amps that are on instead of turning them off?
> Thanks


 

 Tomb (at least used to) sell that chip on Beezar...


----------



## daves440

Thanks Tom , Could you tell me what Wolfson dac chip to order?  Thanks for your help!


----------



## daves440

O.K.Yes it is availible at Beezar, Thank you Tom and Scot. I will let you know how it worked out.!


----------



## tomb

Quote: 





daves440 said:


> O.K.Yes it is availible at Beezar, Thank you Tom and Scot. I will let you know how it worked out.!


 
  Just curious, but are you aware of the grubDAC website?  Anything you want to know about the grubDAC is there:
http://www.diyforums.org/GrubDAC


----------



## tomb

Quote: 





tomb said:


> Just curious, but are you aware of the grubDAC website?  Anything you want to know about the grubDAC is there:
> http://www.diyforums.org/GrubDAC


 
   
  Quote: 





daves440 said:


> O.K.Yes it is availible at Beezar, Thank you Tom and Scot. I will let you know how it worked out.!


 
  No problem - I think I realized who you are, now.


----------



## hyperion007

Hi,
   
  I just built my grubDac two days ago. It detects fine in Windows 7, but there is a kind of digital noise coming from the speakers when no source is playing. I think I can hear something not right when music is playing but cannot put my finger on it.
   
  I have checked and rechecked everything. shining a strong light through the PCB to check for bridges, reflowed some pins etc etc. checking with my 5X lupe I cannot see anything wrong.
   
  Any ideas? btw, I have been looking through this thread and google without finding a solution. I mean, it is ALMOST working perfectly


----------



## tomb

Quote: 





hyperion007 said:


> Hi,
> 
> I just built my grubDac two days ago. It detects fine in Windows 7, but there is a kind of digital noise coming from the speakers when no source is playing. I think I can hear something not right when music is playing but cannot put my finger on it.
> 
> ...


 
  Usually - if it's audible noise, it's something in the analog output.  This may sound silly, but check your output connections - do you have good solder joints at the leads, no stray wires intermittently touching the other pads, ground wires have good, solid connections to the ground pads?


----------



## hyperion007

After a friend of mine took the PCB to work and had a look at it under a microscope and re-soldered everything I had high hopes for a working grubDAC tonight. No such luck. The LED was still flickering and the sound was clipping and sounding terrible.
  I then utilized my new hot air rework station and a generous amount of flux to both ICs, still the same problem. 
   
  Stable 3.3V and 5V
   
  I have had it hooked up to a Trust USB 2.0 hub, but for no reason we tried hooking it up to a USB port on the motherboard instead, and TADAAAAA! no more flickering LED and sounds great!
   
  The USB hub is externally powered and only had two bluetooth dongles in it so should have plenty of power so I don't know why it was acting the way it was.
   
  Anyway, thought I would share this with everyone in case someone has the same problem.
   
   
  /Daniel S


----------



## tomb

Quote: 





hyperion007 said:


> After a friend of mine took the PCB to work and had a look at it under a microscope and re-soldered everything I had high hopes for a working grubDAC tonight. No such luck. The LED was still flickering and the sound was clipping and sounding terrible.
> I then utilized my new hot air rework station and a generous amount of flux to both ICs, still the same problem.
> 
> Stable 3.3V and 5V
> ...


 
  Yep - I think people have been having similar problems with the ODAC.  I would worry about the PupDAC being connected to some sort of hub, too.  A high-quality, linear-regulated USB audio DAC is going to pull a lot of current and if the USB connection is not adequately supplied, it will drop voltage and knock off the DAC or cause other issues.  I can't speak for cobaltmute, the grubDAC/SkeletonDAC/PupDAC designer, but as DIY-er's, I would think one would design almost to the limits of the USB connection - on purpose.  That would ensure that one was getting the best possible performance from what is available for the design.
   
  So, yes - glad to hear that everything is OK and we should probably all take care in where we plug-in a quality audio USB-powered DAC.


----------



## scootsit

Quote: 





tomb said:


> Quote:
> 
> 
> 
> ...


 

 I still have not built mine, but I have the opposite problem. My onboard usbs are too low-current to power my external harddrive much at all, when I hook it up to my hub, I get 10x the data transfer speeds, maybe even more.
   
  Oops, that was meant about the Pupdac, but well the statements about the usb ports stands.


----------



## hyperion007

What is the output impedance of the grubDAC? I want to hook it up to a PGA4311 that needs a source impedance of 600 Ohms or less.
   
  I haven't found this information anywhere.


----------



## DingoSmuggler

Quote: 





hyperion007 said:


> What is the output impedance of the grubDAC? I want to hook it up to a PGA4311 that needs a source impedance of 600 Ohms or less.
> 
> I haven't found this information anywhere.


 
  110 ohms


----------



## Caretaker007

I was hoping that I wouldn't need to post here for help but I am stumped.  While I have a decent amount of experience soldering, this is first time with SMDs.  I tried search the forum for similar issues and answers with no luck.  So here I go....
   
  Everything is soldered on the board except for the leads going out.  I plugged in the device to my Windows 7 desktop and it showed it trying to install the drivers for 3 different components (one was a USB DAC) but it failed.  Unplugged and plugged back in, and this time shows up as Unknown Device.  I then notice a small amount of smoke coming from the PCM chip.  Unplug again found a bridge and fixed it.  Plug back in, no smoke, but nothing from the computer.  Ugh!  I start searching for another bridge.  I suspected there was one near C9 but I failed to desolder the excess and in my tired state I try to scrape it off but realized that is the ground plate it should make a difference if there is a bridge there. Gave up for the day.
   
  Next day, I started testing continuity on the chips but nothing stuck out. I tried it on my laptop this time with nothing else plugged in the usb ports.  After plugging it in, I didnt see anything happening so I unplugged but right after that Windows should a notification that the device was properly installed with a USB DAC listed.  So plugged it back in, but the device shows up as Unknown Device again and every time I try again.  LED is lighting up and the voltage on the LED leads shows 3.24v .
   
  I also want to note that the LED is mounted upside-down on purpose and the I replaced C1, C5 and C15 capacitors with these: http://www.mouser.com/Search/ProductDetail.aspx?R=ECA-0JHG471virtualkey66720000virtualkey667-ECA-0JHG471
   
  Is the PCM fried?  Is there any thing else I can test?  Any advise or suggestions would be helpful!


----------



## scootsit

It looks like there are 3 or 4 bridged pins on the USB chip.


----------



## Caretaker007

Quote: 





scootsit said:


> It looks like there are 3 or 4 bridged pins on the USB chip.


 

 I think I am missing something then.  Can you point them out? 
   
  The only bridges I see are on the U1 in accordance with the board layout.


----------



## tomb

Quote: 





caretaker007 said:


> I think I am missing something then.  Can you point them out?
> 
> The only bridges I see are on the U1 in accordance with the board layout.


 
  There are only two "bridges" by the traces on the PCB.  Your circle in the upper right is a solder bridge
	

	
	
		
		

		
		
	


	




.
   
  It looks like R9 is only soldered on one side, too (on the backside of the PCB). (EDIT: Could be the angle of the photo.  I was going to say R5, too, but it looks fine in one pic.)  You might look at that, too.  Your work looks pretty good.  Hopefully, the PCM chip is not damaged and things will work when you get this fixed.


----------



## Caretaker007

Quote: 





tomb said:


> There are only two "bridges" by the traces on the PCB.  Your circle in the upper right is a solder bridge
> 
> 
> 
> ...


 
  Is the layout here out of date for U1: http://www.diyforums.org/GrubDAC/layout/GrubDAC-laytop.jpg
   
  The upper right circle is just a ground "bridge".  Either way, I forced the removal of the bridge but that pin is still grounded.
   
  R9 looks ok, Resistance from C17 to C12 is 110 Ohms as expected. 
   
  R5 also checks out ok. Reflowed both resistors just to be sure.
   
  Still showing up as a Unknown Device.  Do I need to replace the PCM chip?


----------



## Avro_Arrow

He's right Tom,,,the three bridges are part of the board.
   
  See this photo: GrubDAC PCB.


----------



## tomb

Depends on what you define as a bridge. I was not referring to the ground "relieved" connection on that single corner pin, but to the apparrent solder bridge to the pin at its left.


----------



## Avro_Arrow

I don't know at what point in the troubleshooting the pictures were taken, but
  I looked at them very closely at their original resolution and I didn't find
  any "unintended" connections. The connection from C9 (?) to the Wolfson
  looks to be on its last legs and my need repair, but otherwise I think the
  soldering job should work. The PCM may be fried by earlier mistakes though.
   
  Just my Nickel (Canada doesn't have the penny any more...).


----------



## tomb

Quote: 





avro_arrow said:


> I don't know at what point in the troubleshooting the pictures were taken, but
> I looked at them very closely at their original resolution and I didn't find
> any "unintended" connections. The connection from C9 (?) to the Wolfson
> looks to be on its last legs and my need repair, but otherwise I think the
> ...


 
  OK - I've been looking at it all this time from my phone and I guess the display left a lot to be desired.  I can see now that I was mixed up (but not about only two bridged pins on the PCB design).  Thanks for correcting me.
   
  I agree if there are no bridges, then the PCM is probably fried.


----------



## Caretaker007

Quote: 





avro_arrow said:


> I don't know at what point in the troubleshooting the pictures were taken, but
> I looked at them very closely at their original resolution and I didn't find
> any "unintended" connections. The connection from C9 (?) to the Wolfson
> looks to be on its last legs and my need repair, but otherwise I think the
> ...


 
   
  The connection from the C9 to the Wolfson looks weird in the photo but I believe I reflowed those pins anyways after the photo was taken.  The continuity tests out fine. 
   
  Quote: 





tomb said:


> OK - I've been looking at it all this time from my phone and I guess the display left a lot to be desired.  I can see now that I was mixed up (but not about only two bridged pins on the PCB design).  Thanks for correcting me.
> 
> I agree if there are no bridges, then the PCM is probably fried.


 
   
  That's what I figured. I just ordered a new PCM.  Hopefully that was the only chip damaged.  
   
  I will report back when it gets in and I have time to repair it.  Hopefully it will be good news.


----------



## Caretaker007

Got the PCM2707 in.  Replaced it.  Triple checked for bridges, both visually and continuity testing. Tested the continuity from the pins to the trace points. Everything looked and tested perfect.
   
  After plugging in, I first noticed the LED flickering and then the regulator was getting very hot.  Unplugged.  Traced and checked ALL of the components for shorts...twice. Nothing.
   
  Plugged back in check the voltages. Before I could start measuring, smoke starts coming from the PCM chip. Fried again!!! 
	

	
	
		
		

		
		
	


	




 
   
  A bunch of the pins are grounded now on the PCM that were definitely not before so definitely fried.  I have another PCM (was intended for a PupDAC build) but I don't trust the board at this point and removing this PCM this time has wrecked the anchor points. 
   
  I refuse to give up and I going to order a new board from Beezer (along with a PupDAC PCB, future project) and I am going to place a reorder for the components at mouser. One problem is that the Crystek Oscillator is no longer stocked at Mouser.  Can someone suggest a alternative or maybe Tom has one he can sell to me and add to my PCB order when I place it?


----------



## tomb

Quote: 





caretaker007 said:


> Got the PCM2707 in.  Replaced it.  Triple checked for bridges, both visually and continuity testing. Tested the continuity from the pins to the trace points. Everything looked and tested perfect.
> 
> After plugging in, I first noticed the LED flickering and then the regulator was getting very hot.  Unplugged.  Traced and checked ALL of the components for shorts...twice. Nothing.
> 
> ...


 
  I am sorry to hear this.
   
  Send me a PM and I'll shoot you a new grubDAC PCB.  If there's any chance it was the PCB, I'd rather just give you another one.  I probably have a crystal, too, although the one we changed to on the pupDAC is OK for the grubDAC, too:
C3391-12.000
   
  Just an FYI, but all the pupDAC PCB's are electrically tested.


----------



## mawoca

Another GrubDAC is alive and well in this world! Aside from a couple of issues that were resolved very quickly by reading through this thread, the build went fast and was a ton of fun! And of course the sound is the ultimate reward, as this blows my little ELE EL-D01 away. Right now I have it paired up with a buffered-ground CMoy (with an OPA2107 in it) and my trusty SR60i's. I had no idea you could get sound like this out of the SR60s, lol. So good! My thanks to Cobaltmute and TomB and everyone who has built one before me for sharing their experiences.

I'm very excited to start building my Pimeta V2 now and finding matching cases for that and the GrubDAC!


----------



## tomb

Quote: 





mawoca said:


> Another GrubDAC is alive and well in this world! Aside from a couple of issues that were resolved very quickly by reading through this thread, the build went fast and was a ton of fun! And of course the sound is the ultimate reward, as this blows my little ELE EL-D01 away. Right now I have it paired up with a buffered-ground CMoy (with an OPA2107 in it) and my trusty SR60i's. I had no idea you could get sound like this out of the SR60s, lol. So good! My thanks to Cobaltmute and TomB and everyone who has built one before me for sharing their experiences.
> 
> I'm very excited to start building my Pimeta V2 now and finding matching cases for that and the GrubDAC!


 
  Thanks!  Glad to hear you like it and that everything worked out!


----------



## acvtre

Hi folks, I've just resoldered the main chips: U1, U3 and another couple because time ago I burned them accidentaly with the multimeter while the dac was on.
  Now the dac got immediately recognized by the pc when I plug in the usb, but I can hear no sound, not even a hiss/buzz from the speakers? 
   
  What should I check?


----------



## tomb

Quote: 





acvtre said:


> Hi folks, I've just resoldered the main chips: U1, U3 and another couple because time ago I burned them accidentaly with the multimeter while the dac was on.
> Now the dac got immediately recognized by the pc when I plug in the usb, but I can hear no sound, not even a hiss/buzz from the speakers?
> 
> What should I check?


 
  You need to check U3 - that's the Wolfson DAC chip and it governs everything about the analog output.


----------



## acvtre

Quote: 





tomb said:


> You need to check U3 - that's the Wolfson DAC chip and it governs everything about the analog output.


 
  Ok, this means that the U1 works perfectly, right? A sidenote: the usb dac got installed every time I plug it in the pc, is it supposed to do so?
   
  What do I have to check about the U3? The solder joints? Some voltages?


----------



## tomb

Quote: 





acvtre said:


> Ok, this means that the U1 works perfectly, right? A sidenote: the usb dac got installed every time I plug it in the pc, is it supposed to do so?
> 
> What do I have to check about the U3? The solder joints? Some voltages?


 
  Have you got some pics of the PCB?  That might tell us what's going on a lot faster than exhausting every possibility by typing posts.
   
  That said, no - there is a possibility that U1 is not working perfectly.  There are a number of traces (through vias to the backside of the PCB) that connect to U3.  Obviously, this is true: the PCM2706/7 takes the USB signal and converts it into a digital stream that the Wolfson chip can convert to analog.  So, there are 4 traces that connect U1 to U3.  If one of those is messed up, or the pin connections to those traces, then U3 is not going to operate.  Three of those traces are on the USB-side of U1 and the fourth trace is on the side next to U3.
   
  Even so, it's been my experience that if the DAC is recognized by the PC, then U1 is all OK.  You raise a good point about every time you connect it, the PC re-installs it.  So, maybe the U1 chip is not working "perfectly."  We're all just making guesses here.  That's what you should do in troubleshooting - try and eliminate all the possibilities.  One of the best things to check is if there is continuity between the U1, U3 chip pins and their traces.  Or, you might try posting pics of your PCB and see if any of us can spot something.


----------



## Avro_Arrow

It has been my experience, that once installed, it doesn't install it again
  as long as you use the same USB port. If you use a different port, it
  see it as a whole new device and installs it again and gives it the next
  number in the sequence.


----------



## acvtre

Quote: 





avro_arrow said:


> It has been my experience, that once installed, it doesn't install it again
> as long as you use the same USB port. If you use a different port, it
> see it as a whole new device and installs it again and gives it the next
> number in the sequence.


 
  Infact I've just plugged it in again and the pc recognized it immediately. Thanks!
  Quote: 





tomb said:


> Have you got some pics of the PCB?  That might tell us what's going on a lot faster than exhausting every possibility by typing posts.
> 
> That said, no - there is a possibility that U1 is not working perfectly.  There are a number of traces (through vias to the backside of the PCB) that connect to U3.  Obviously, this is true: the PCM2706/7 takes the USB signal and converts it into a digital stream that the Wolfson chip can convert to analog.  So, there are 4 traces that connect U1 to U3.  If one of those is messed up, or the pin connections to those traces, then U3 is not going to operate.  Three of those traces are on the USB-side of U1 and the fourth trace is on the side next to U3.
> 
> ...


 
  Some pics: 

   
  I've just tested the voltage between a pin of the U1 and one of the U3 chosen at random and found continuity.


----------



## tomb

Well, after studying these pics pretty extensively, I don't see any bridges in the pins of U1 and U3.  That leaves a couple of possibilities: 1) your wiring is messed up or shorted - can't tell what's going on with those output wires and whether you have them shorted, perhaps, or 2) the DAC chip is burned up.  At least in one photo, the chip and pins look like it went through a lot.  I don't know this for certain, but I think the PCM2706/7 can take a lot more abuse than the Wolfson DAC chip.  The fact that the DAC chip is smaller may mean it can't dissipate as much heat while it's being soldered.
   
  The 3.3V should be OK, or U1 wouldn't work and it wouldn't be recognized by the PC.  The DAC chip uses the same voltage.  Unfortunately, all the voltage conversion for the analog output is internal to the Wolfson DAC.  Because of the charge pump inside the DAC chip, there should be zero DC on the outputs anyway.  So, attempting to measure the AC signal voltage at output would be problematic.  You could confirm for us that there is no offset in the output - that would at least eliminate one red flag.  Hopefully, your DAC chip is OK. 
   
  Also - I can't tell from the pics, but you should look at your clock oscillator.  Sometimes people have gotten the solder from the pads over on top of the oscillator.  If the solder is touching both the metal top and one of the pads, the oscillator will be shorted out.  I sort of think the PCM2706/7 wouldn't work, either, but I'm not certain.  Anyway, that's another thing to check.
   
  The next step you might take is to trim all those leads on the bottom of the PCB from the through-hole parts and the wiring.  Then make sure that the wiring to your outputs is correct, not shorted, etc.  Use your meter to determine continuity or any shorts.


----------



## acvtre

Quote: 





tomb said:


> ...snip...


 
  The pics of the clock:

   

   
  As you can see the clock doesn't seem to have solder on its top.
   
  Sorry for the noob question, but how can I measure the offset?


----------



## tomb

Quote: 





acvtre said:


> <snip>
> As you can see the clock doesn't seem to have solder on its top.
> 
> Sorry for the noob question, but how can I measure the offset?


 
  Put one probe on the ground pad at the input and the other at the signal output - either Left or Right signal wire.  See if you measure any DC voltage.


----------



## acvtre

Quote: 





tomb said:


> Put one probe on the ground pad at the input and the other at the signal output - either Left or Right signal wire.  See if you measure any DC voltage.


 
  Measured also the offset voltage. I measure something like 2.7mV, so really really low DC voltage, it should be ok, right?
   
  A thing that I'm not sure about is if every pin of the U3 is soldered.


----------



## tomb

Quote: 





acvtre said:


> Measured also the offset voltage. I measure something like 2.7mV, so really really low DC voltage, it should be ok, right?
> 
> A thing that I'm not sure about is if every pin of the U3 is soldered.


 
  Yes, 2.7mV is not bad.  It should be lower, but we can't tell what kind of meter you have and that may be at the limits of its precision.  Still, it doesn't sound like a worry.
   
  As for checking the pins on U3 - this should be done carefully (power off!), but you should be able to place one probe of your meter on top of the pin as it exits the chip's plastic body and then follow the trace the pin is supposed to be soldered to another place on the PCB.  Place your other probe there.  Measure for zero resistance.  If you get something else, chances are the pin is not soldered.  You have to be careful with the right touch, though, because it's possible to press down hard enough on the pin to make contact with the trace even if it's not really soldered.
   
  Similarly, you can place your probes on adjacent pins to see if they're bridged (zero resistance).  You have to reference this to the schematic/layout on the GrubDAC website, however, because several pins are supposed to be connected together.


----------



## mikechml

I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?


----------



## tomb

mikechml said:


> I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?


 
  
 Unfortunately, I'd have to say this is normal.  It may be a by-product of a high-performance DAC (meaning a fairly high current draw) under current limits of a USB buss.  The transient current draw may be too much for the PC.  I've accepted it as an irritation, nothing more.
  
 Things could be a lot worse - on the Alien or BantamDAC, it usually meant the DAC was fried.
	

	
	
		
		

		
			





  I had it happen to me today at work with my pupDAC and a Mini3 (no damage, though!).  This happened even with a powered USB hub while I was plugging power into the Mini3 - but it was turned on when I was doing it - probably not a good idea.  I've also had the same thing happen with external (self-powered) USB disc drives.  I've had to un-plug and re-plug them back in before they were recognized by the PC again.
  
 Bottom line, I would always be careful with power plug-ins/un-plugs when USB devices are connected.


----------



## cobaltmute

mikechml said:


> I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?


 
  
 As Tom has said, this appears to be normal.  I have some suspicions as to what causes it, but haven't had time to track it down. 
  
 It does appear to be related to spikes on the mains power that get fed into the dac (either via to output or the PC side).  Similar kinds of things happen when I run turn on/off a desktop lamp near my rig.
  
 As a test, if you are comfortable with removing parts, I might try to remove C5.


----------



## zhoob2004

So I built my grubdac a couple years ago and due to various circumstances I never managed to get it working. Yesterday I finally got to work and fixed a bridge on u2 so now it works.

But here's the catch, it will work for a bit, but then The sound will cut out, and reconnecting it doesn't change it. I also have some issues of the device not being recognized on Linux. I'll have pics up in an hour or so, but any ideas of common faults in the meantime?


----------



## tomb

zhoob2004 said:


> So I built my grubdac a couple years ago and due to various circumstances I never managed to get it working. Yesterday I finally got to work and fixed a bridge on u2 so now it works.
> 
> But here's the catch, it will work for a bit, but then The sound will cut out, and reconnecting it doesn't change it. I also have some issues of the device not being recognized on Linux. I'll have pics up in an hour or so, but any ideas of common faults in the meantime?


 
 It's all still related.  All USB connections are governed by U1, the PCM2707/6 chip, and the 3.3VDC power supply necessary to power it - U2.


----------



## zhoob2004

3v3 is good, even when it stops responding, just to put that out there. I suppose I'll try to reflow everything again and take pics

Sent from my One using Tapatalk


----------



## tomb

zhoob2004 said:


> 3v3 is good, even when it stops responding, just to put that out there. I suppose I'll try to reflow everything again and take pics
> 
> Sent from my One using Tapatalk


 
 Then there's something probably going on with the PCM chip.
  
 The GrubDAC may get knocked offline if there's a power issue - something gets plugged-in/un-plugged, some other power load turning on or off, etc.  It should not refuse to re-connect, however, and there shouldn't be an issue with Linux.


----------



## zhoob2004

Well now I'm only getting ~1v on the 3v3 so I guess I'll work on that and see what happens


----------



## tomb

zhoob2004 said:


> Well now I'm only getting ~1v on the 3v3 so I guess I'll work on that and see what happens


 
 Makes sense - good luck!


----------



## zhoob2004

ok, so I fixed the 3v3 (didn't connect fully when I resoldered it).
  
 now the symptom I'm having is it connects just fine, recognized by lsusb and alsa. Then, after a short bit, I lose it and dmesg says "Port disabled by hub (EMI?), re-enabling..." after which, it doesn't show up.
  
 here is a pic of the topside I just took, not sure if you can see anything or not,
  
 http://img9.imageshack.us/img9/9046/4ukb.jpg
  
or at least there would be if I had upload permissions. I'll see if after I post this I have enough posts and then I can edit this one with it, or I'll just use imageshack or something.


----------



## geofftnz

zhoob2004 said:


> http://img9.imageshack.us/img9/9046/4ukb.jpg


 
  
 I'd look at getting some solder wick and getting rid of the extra solder on the crystal oscillator. I had problems on my pupdac with too much solder on the oscillator shorting against the case (was so small I didn't notice it initially). USB hubs will disable devices if they draw too much power, so that's an option too, although you should have noticed regulators/inductors getting super-hot.
  
 Is that a small bridge lower right-side of the PCM2706?


----------



## tomb

zhoob2004 said:


> ok, so I fixed the 3v3 (didn't connect fully when I resoldered it).
> 
> now the symptom I'm having is it connects just fine, recognized by lsusb and alsa. Then, after a short bit, I lose it and dmesg says "Port disabled by hub (EMI?), re-enabling..." after which, it doesn't show up.
> 
> ...


 
  
  


geofftnz said:


> I'd look at getting some solder wick and getting rid of the extra solder on the crystal oscillator. I had problems on my pupdac with too much solder on the oscillator shorting against the case (was so small I didn't notice it initially). USB hubs will disable devices if they draw too much power, so that's an option too, although you should have noticed regulators/inductors getting super-hot.
> 
> Is that a small bridge lower right-side of the PCM2706?


 
  
 Excellent photograph!
  
 Geofftnz is correct - if you solder flowing up and touching the top "can" of the oscillator, it will be shorting out.  Could be a miniscule bridge on the PCM chip as he notes, but it looks like either lint or something you could easily swipe away with an X-acto knife.  Except for that, all the joints on the PCM and Wolfson look pretty good to me.


----------



## zhoob2004

I think I saw what you mean by the potential bridge, and it was just a piece of lint. I touched it up anyway just to be sure, though. I checked all my connections that I could with a multimeter and a cursory inspection of where traces connected (using the layout and board images on the site mostly). I've been trying it on and off for a while now and not got any recognition from the computer, or my error and then suddenly, I plug it in and it works just like magic. I'm testing it on my desktop right now (booted into linux right now) and the audio dropped on me once, but I attribute that to an application taking exclusive control of the device away because after I restarted playback it began to work again. Now I'm just running it for a while with music to see if I can't get it to drop again, but it seems more stable than it has been so far.
  
 only thing I notice is there is a high-pitched squeal coming from the speakers, but that may be my monitor speakers or it's integrated amp (I apologize for not having a proper setup to test/use this with currently, penniless college student)
  
 I'm also sure it wasn't the crystal because I checked continuity between the top and the 4 contacts and only the bottom-right (which I'm pretty sure is already ground) had continuity
  
  
 Edit: 
  
 If I want to drive IEMs directly with my grubdac, what should I do to make it sound right? the bass is really washed-out if I try


----------



## tomb

zhoob2004 said:


> I think I saw what you mean by the potential bridge, and it was just a piece of lint. I touched it up anyway just to be sure, though. I checked all my connections that I could with a multimeter and a cursory inspection of where traces connected (using the layout and board images on the site mostly). I've been trying it on and off for a while now and not got any recognition from the computer, or my error and then suddenly, I plug it in and it works just like magic. I'm testing it on my desktop right now (booted into linux right now) and the audio dropped on me once, but I attribute that to an application taking exclusive control of the device away because after I restarted playback it began to work again. Now I'm just running it for a while with music to see if I can't get it to drop again, but it seems more stable than it has been so far.
> 
> only thing I notice is there is a high-pitched squeal coming from the speakers, but that may be my monitor speakers or it's integrated amp (I apologize for not having a proper setup to test/use this with currently, penniless college student)
> 
> ...


 
 One other possibility is either flux or cleaning fluid (I use alcohol) that's gotten under one of the chips.  It can cause intermittent shorting.  I've had to wait for several hours before plugging in a pupDAC after cleaning it.  Otherwise, all sorts of weird things happen.


----------



## zhoob2004

could be that, as I have been cleaning with alcohol (80%, not as high as I like, but all I could get easily), but I didn't hear it in my headphones (but there are a lot of things I didn't hear in the headphones, like proper music).
  
 I suspect that the issue with the headphones might be due to the integrated microphone, since I've seen that cause issues with computer audio output before.


----------



## tomb

zhoob2004 said:


> could be that, as I have been cleaning with alcohol (80%, not as high as I like, but all I could get easily), but I didn't hear it in my headphones (but there are a lot of things I didn't hear in the headphones, like proper music).
> 
> I suspect that the issue with the headphones might be due to the integrated microphone, since I've seen that cause issues with computer audio output before.


 
 91% alcohol is readily available at Wal-Mart.


----------



## zhoob2004

let me rephrase that: 80% is all that I could get for free and on a moment's notice, but no matter, because it's been working great since I last posted, although something is up with my audio drivers on my linux install since it only likes to have one application using it at a time.


----------



## tomb

zhoob2004 said:


> let me rephrase that: 80% is all that I could get for free and on a moment's notice, but no matter, because it's been working great since I last posted, although something is up with my audio drivers on my linux install since it only likes to have one application using it at a time.


 
 Sounds like it might have been the alcohol.
	

	
	
		
		

		
		
	


	




   Glad you got it working, but sorry about the Linux issues.


----------



## zhoob2004

No worries. It's probably something that's my fault anyway. That's the cost you pay for using Arch as your distro of choice.


----------



## Rodeodave

Okay, so a couple of months ago I got gifted a *GrubDAC *kit. Built it up nice and clean, added a few mods here and there, and I must say that I really, really like the sound of this little thing. Balanced sound, no coupling caps, nice output level. BUT what was annoying me to no end were the *HF interferences* manifesting themselves as *clicks*, *pops*, and especially *drop-outs* of the DAC whenever any power switch of some sorts was actuated. Anything from the fridge, oscilloscope, soldering station, light switch in any room of my apartment, maybe even one or two power sources that my neighbour is running, it all disturbed the DAC in some varying degree.
  
 For reference, here's the *setup *that I was dealing with: Netbook to (bus powered) GrubDAC via super short USB cable, from there shielded RG316/U cable with BNC plugs to the input of my preamp. At the input was a 25k Alps pot, connected via Cat5e twisted pairs, going into a DC coupled unity gain JFET buffer (a so called DCB1 Mezmerize), which then connects to an active crossover that feeds two stereo amps. Here's a pic:
  

  
 The crappy boar shaving brush (too floppy when wet, no backbone) is my dedicated electronics dust-off brush, I highly recommend it.
  
 On with the story. Trying to get rid of these interference issues, I implemented many a thing. My source is a netbook, so I ran it on battery. Didn't change a thing, it seemingly wasn't entering the DAC from this side. Added ferrite cores, chokes, line filters to preamps and amps (100% DIY), bypass and decoupling caps, bigger resistors and bigger caps (not that I expected anything from those last two), nothing changed. Then I googled and saw that other people are having that problem too, but no solution was to be found. The GrubDAC looks like this now:
  

  
  
 Unrelated to the DAC issues I added something to my system yesterday: Another JFET buffer with relay based source selection, for convenience really. Here's another pic:
  

  

 The GrubDAC connects to the two BNC connectors (to the left of the two unoccupied RCA jacks). As you can see the whole thing is not exactly inside a chassis. The whole pre doesn't even have a line filter at the mains input. Noticed how the first paragraph is in past tense? That's right, the *issues are gone*.
*What changed?* I left the volume control where is was before, at the input of the Mezmerize. In front of the volume pot I added the additional JFET buffer, and at this buffer's input I simply put two 22k1 Dale RN60D resistors to ground (instead of a pot), which in parallel to the buffer's own input impedance form a *fixed(!) input impedance* of pretty much 20k. The rest is virtually the same. The same cables, the same plugs, the same circuitry. The relays are Nais TQ2-5V and I doubt that they have something to do with the resolving of the issue. All the buffers use the same JFETs (2SK170BL) and resistors (RN55D), all unity gain, no coupling caps.
 So the *new setup* is: Netbook, GrubDAC, fixed 22k1 RN60D resistor, buffer, volume pot, buffer, crossover, amps.
  
 I'm still not sure what is actually going on, but the simple resistor at the input must have a flatter impedance than the pot for the HF portions of the power switch spark e/m crap. Or something like that.
 TL;DR: Buffer your volume pots.
 I hope this helps. Comments, criticism and alternative explanations welcome.


----------



## tomb

rodeodave said:


> Okay, so a couple of months ago I got gifted a *GrubDAC *kit. Built it up nice and clean, added a few mods here and there, and I must say that I really, really like the sound of this little thing. Balanced sound, no coupling caps, nice output level. BUT what was annoying me to no end were the *HF interferences* manifesting themselves as *clicks*, *pops*, and especially *drop-outs* of the DAC whenever any power switch of some sorts was actuated. Anything from the fridge, oscilloscope, soldering station, light switch in any room of my apartment, maybe even one or two power sources that my neighbour is running, it all disturbed the DAC in some varying degree.
> 
> For reference, here's the *setup *that I was dealing with: Netbook to (bus powered) GrubDAC via super short USB cable, from there shielded RG316/U cable with BNC plugs to the input of my preamp. At the input was a 25k Alps pot, connected via Cat5e twisted pairs, going into a DC coupled unity gain JFET buffer (a so called DCB1 Mezmerize), which then connects to an active crossover that feeds two stereo amps. Here's a pic:
> 
> ...


 
  
 Your particular setup, while quite interesting and unique, is so non-standard that I'd only be guessing.
  
 I'm not sure that others have necessarily commented on _sound glitches or interference_ with the GrubDAC, but my memory is not so good these days.  JMHO, but an open amp with unshielded hookup wire seems more likely to pick up those noises than the DAC.  Cell phone interference, for instance, can be maddening sometimes but they usually enter into a circuit through the large traces, leads, and wiring associated with amplifier connections.  The DAC knocking offline because of power switching?  Yes, absolutely.  In my own setup, I even have a powered-USB hub and sometimes my mouse or keyboard gets knocked offline when I throw the power switch on to my headphone amp.  Things re-connect almost instantly, so it's a minor irritation.
  
 As for the volume pot - every pot should have an input grounding resistor (tied between the wiper and ground ~10x the pot impedance) or the source will see a varying impedance as the volume control is adjusted.  It's possible that the Wolfson chip would misbehave in those circumstances.  I'm not sure if you included that before, but if not, maybe your resistors corrected that issue.
  
 Is your super-short USB cable to the GrubDAC shielded?  That could cause issues, too, if not.


----------



## Rodeodave

Just 20 posts ago you commented on this exact issue it seems. http://www.head-fi.org/t/445155/the-grubdac/960#post_9777034
 And of course that USB cable is shielded, and properly terminated at both ends.
 The wiper-to-ground resistor is not really that common though.


----------



## tomb

rodeodave said:


> Just 20 posts ago you commented on this exact issue it seems. http://www.head-fi.org/t/445155/the-grubdac/960#post_9777034
> And of course that USB cable is shielded, and properly terminated at both ends.
> The wiper-to-ground resistor is not really that common though.


 
 Sorry, but this was what I stated in the previous post: _The DAC knocking offline because of power switching?  Yes, absolutely. _?  That is the subject of the other post you just referenced.  I also beg your pardon, but you'll find the wiper-to-ground resistor in every reputable DIY design:
  
 Millett Hybrid
 Millett MiniMAX
 Torpedo
 CMoy
 PPAV1 and PPAV2
 PIMETA
 M3
 B22
  
 just to name a few ...
  
 I wasn't trying to set up some sort of competition about what was said or not said ... just trying to offer some guesses as to what could cause the issue with respect to interference.  Power issues should be viewed as a separate matter, IMHO.
  
 EDIT: for politeness, excuse me ...


----------



## Rodeodave

tomb said:


> Sorry, but what part of this in my previous post did you not read: _The DAC knocking offline because of power switching?  Yes, absolutely. _?  That is the subject of the other post you just referenced.  I also beg your pardon, but you'll find the wiper-to-ground resistor in every reputable DIY design:
> 
> Millett Hybrid
> Millett MiniMAX
> ...


 
  
 I apologize, it's late, my attention span is getting low. I got hung up with the glitches and interference part. My mistake. It got me really confused because I just had read your post I linked to before.
  
 And the resistor to ground thing I got wrong too, that's what I meant with "buffer's own input impedance", it's a 221k resistor to ground at the wiper. I confused it with the 1M resistors that you sometimes find at the input jacks.
  
 I should read more closely.


----------



## tomb

rodeodave said:


> I apologize, it's late, my attention span is getting low. I got hung up with the glitches and interference part. My mistake. It got me really confused because I just had read your post I linked to before.
> 
> And the resistor to ground thing I got wrong too, that's what I meant with "buffer's own input impedance", it's a 221k resistor to ground at the wiper. I confused it with the 1M resistors that you sometimes find at the input jacks.
> 
> I should read more closely.


 
 I should apologize, too.


----------



## HiGHFLYiN9

Wow! That's quite the GrubDac, some sexy cap choices there  Let us know when you get 'er running!


----------



## mikechml

cobaltmute said:


> As Tom has said, this appears to be normal.  I have some suspicions as to what causes it, but haven't had time to track it down.
> 
> It does appear to be related to spikes on the mains power that get fed into the dac (either via to output or the PC side).  Similar kinds of things happen when I run turn on/off a desktop lamp near my rig.
> 
> As a test, if you are comfortable with removing parts, I might try to remove C5.


 
   
 So I finally got some time to get back to debugging this. Thanks for the info.
  
 Removing C5 didn't help.
 I'm currently using the setup with my laptop and it's made the problem a bit easier to track down, it also reconnects the DAC automatically which is nice. I'm fairly sure that it's a spike being fed back from the mains via the output to the amp, I can trigger the problem by turning my soldering iron off (plugged into the same strip as the amp) while the DAC is powered from my laptop (on battery power). dmesg log below.
 I'm also finding that the DAC is unusable when my laptop is plugged into the mains. I am using a cheap replacement charger though so that's probably not helping.
  
 Any ideas for workarounds?
  
 I'll try to get some 'scope shots of what's happening on the grubdac outputs after the holidays.
  


> [20837.640106] usb 3-1: new full-speed USB device number 19 using uhci_hcd
> [20837.834359] usb 3-1: New USB device found, idVendor=08bb, idProduct=2706
> [20837.834372] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
> [20837.834379] usb 3-1: Product: USB Audio DAC
> ...


----------



## KimLaroux

I finished building my first grubdac yesterday. Washed it with flux cleaner then waited for today to try it.
  
 The moment I plugged it in, U2 went up in smoke.
  
 Has this happened to anyone else? Any tips as to what may have caused it?
  
 Sorry I don't have anything to take usable pictures.


----------



## tomb

kimlaroux said:


> I finished building my first grubdac yesterday. Washed it with flux cleaner then waited for today to try it.
> 
> The moment I plugged it in, U2 went up in smoke.
> 
> ...


 

 I'm not quite sure that it's happened to anyone else, although we've perhaps had plenty who have mentioned U2 getting hot.  The GrubDAC is not a complex build.  It's really a matter of soldering all the pins correctly on the SMD chips like U1, U2, and U3.  If U2 went up in smoke, something was shorted, plain and simple.
  
 You state you "don't have anything to take usable pictures."  Unfortunately, that would be the first suggestion: post some clear photos to see if anyone can see the short.


----------



## KimLaroux

I planned on ordering a few U2 with my Carrie order. Sadly the part number listed in the BOM (595-TPS79333DBVRQ1) is out of stock for the next 17 weeks. Is there an alternative to this chip I can find at Mouser?


----------



## tomb

kimlaroux said:


> I planned on ordering a few U2 with my Carrie order. Sadly the part number listed in the BOM (595-TPS79333DBVRQ1) is out of stock for the next 17 weeks. Is there an alternative to this chip I can find at Mouser?


 

 Yes, any TPS79333 will work with the same planform (not sure it comes in any other package).
  
 Simply type in "TPS79333" in the Mouser search.  The first one I get (in a list of 6) says there's 13,954 in stock at 84 cents each. (TPS9333DBVR)


----------



## KimLaroux

tomb said:


> Yes, any TPS79333 will work with the same planform (not sure it comes in any other package).
> 
> Simply type in "TPS79333" in the Mouser search.  The first one I get (in a list of 6) says there's 13,954 in stock at 84 cents each. (TPS9333DBVR)


 
  
 Thanks! With that, I managed to order everything from Mouser. It's great not having to place a second order from a second supplier and not pay shipping again.


----------



## KimLaroux

Ok I replaced U2 and I get the same problem.
  
 I checked for shorts trough a lamp, nothing.
  
 I measured for shorts using my multimeter. Nothing between pins on the chips. Measuring between 3V3 and 0V, I get 1.5K one way once caps are charged, and 485R the other way.
  
 The 3V3 rail moves up and down around 2.3V. U2 is burning up again and smelling like magic smoke.
  
 *scratches head*
  
 Edit : 
  
 The first time I plugged the DAC today, nothing showed up on Dmesg and U2 was not heating up, though the 3V3 rail was still at 2.3V
  
 The second time I connected it, after reflowing a few pins, U2 heated up and smelled like burned electronics, but I got this on Dmesg:
  

```
[17427.235222] usb 6-1: new full-speed USB device number 2 using uhci_hcd [17427.348134] usb 6-1: device descriptor read/64, error -71 [17427.561130] usb 6-1: device descriptor read/64, error -71 [17427.764223] usb 6-1: new full-speed USB device number 3 using uhci_hcd [17427.877117] usb 6-1: device descriptor read/64, error -71 [17428.090227] usb 6-1: device descriptor read/64, error -71 [17428.293197] usb 6-1: new full-speed USB device number 4 using uhci_hcd [17428.702118] usb 6-1: device not accepting address 4, error -71 [17428.804114] usb 6-1: new full-speed USB device number 5 using uhci_hcd [17429.212084] usb 6-1: device not accepting address 5, error -71 [17429.212127] hub 6-0:1.0: unable to enumerate USB device on port 1 [17494.544134] usb 6-1: new full-speed USB device number 6 using uhci_hcd [17494.656125] usb 6-1: device descriptor read/64, error -71 [17494.869131] usb 6-1: device descriptor read/64, error -71 [17495.072226] usb 6-1: new full-speed USB device number 7 using uhci_hcd [17495.185108] usb 6-1: device descriptor read/64, error -71 [17495.399106] usb 6-1: device descriptor read/64, error -71 [17495.602128] usb 6-1: new full-speed USB device number 8 using uhci_hcd [17496.011113] usb 6-1: device not accepting address 8, error -71 [17496.113137] usb 6-1: new full-speed USB device number 9 using uhci_hcd [17496.522119] usb 6-1: device not accepting address 9, error -71 [17496.522162] hub 6-0:1.0: unable to enumerate USB device on port 1
```
  
  
 Edit 2 : 
  
 Apparently I'm not the first to have this problem http://www.head-fi.org/t/445155/the-grubdac/660#post_7350187

 Sadly the person gave up and built a new kit.


----------



## tomb

It's possible the PCB has a fault.  We sell them pretty cheaply and an electrical check wasn't included in the production order.  That said, I'm only really aware of one, perhaps two that had a defect.
  
 We could still use some pics.  There's definitely a short somewhere, or U2 would not heat up like that.


----------



## KimLaroux

I reflowed everything, reseated some parts that were not perfectly aligned. I then gave it a shower of flux cleaner and cleaned it with a brush. I'll leave it to dry over night and try again tomorrow. 
  
 I'll borrow a friend's camera and take pictures Friday.


----------



## KimLaroux

Well, this is interesting.
  
 Plugging the DAC today, it's still not recognized. I get the same dmesg error. I had the same 2.3 V when I plugged it in.
  
 But the voltage slowly rose, and leaving it plugged for a while, it slowly rose to 3.30 V. Reconnecting the USB cable doesn't change anything though, it's still not recognized.
  
 This is simply Le weird.
  
 Is there a way to debug the PCM2707 to verify if it's working?


----------



## tomb

kimlaroux said:


> Well, this is interesting.
> 
> Plugging the DAC today, it's still not recognized. I get the same dmesg error. I had the same 2.3 V when I plugged it in.
> 
> ...


 

 If there is a way to debug a PCM2707, I'm not aware of it.  I once built a pupDAC and used too-high a soldering temperature on my Hakko.  It fried the PCM2707, but it was h*ll figuring that out.
  
 Despite that statement above, I can't seriously suggest that's what happened to your DAC - sight unseen.  I still think something is shorting out.  In my case above, every single voltage on the PCB was right on.  It just didn't work.  Yours seems to be a different issue.


----------



## wakibaki

Hi Kim.
  
 Checking for shorts (the most likely cause) only takes a few minutes on an IC, you just walk the probes along the row of pins. 
  
 There are only a limited number of pins on this board. The next thing is to go through them all with a DMM set to beep, making sure that all the connections that should be made, _are_ made, and that there are none that shouldn't. You may be able to get a netlist, most schematic capture packages export one to their accompanying PCB layout tool, and many export one in a standard format. If not, writing one is not that big a job for a board this simple, and working from the netlist is less hassle than working from the schematic.
  
 Once you're satisfied that the connectivity is good, then is the time to start thinking about component issues. 
  
 It's depressing when things don't work, and it's easy to slide into thinking along the lines 'I'll never get to the bottom of this', but all build faults eventually yield to steady, grinding application.
  
 w


----------



## tomb

Great post, Waki - thanks!
  
 Let us know what you find, Kim!


----------



## KimLaroux

tomb said:


> If there is a way to debug a PCM2707, I'm not aware of it.  I once built a pupDAC and used too-high a soldering temperature on my Hakko.  It fried the PCM2707, but it was h*ll figuring that out.
> 
> Despite that statement above, I can't seriously suggest that's what happened to your DAC - sight unseen.  I still think something is shorting out.  In my case above, every single voltage on the PCB was right on.  It just didn't work.  Yours seems to be a different issue.


 
  
  
 Ah snap! That could very well be it! My iron was set very hot, as I was using it for large point to point soldering. I did not think about lowering it as I figured it wasn't gonna be an issue if I left the iron on the pins only a second. But with the number of pins on those chips, I could have over-heated it.
  
 How did you come to the conclusion the chip was fried? Any definitive test I can run?
  


wakibaki said:


> Hi Kim.
> 
> Checking for shorts (the most likely cause) only takes a few minutes on an IC, you just walk the probes along the row of pins.
> 
> ...


 
  
 I did check for shorts between every pins on the chips. Nothing.
  
 What's a netlist?
  
 And in case you haven't noticed, you're talking to a girl who took over 2 years to design, build, (debug, redesign, rebuild)*20 an hybrid amp. Giving up is not one of my virtues. 
	

	
	
		
		

		
		
	


	




  I'm just learning along, so it takes a while.


----------



## Avro_Arrow

kimlaroux said:


> What's a netlist?


 
  
 A netlist is a term used in board design.
  
 It is simply a list of which pin is connected to which other pin or pins.


----------



## tomb

kimlaroux said:


> tomb said:
> 
> 
> > If there is a way to debug a PCM2707, I'm not aware of it.  I once built a pupDAC and used too-high a soldering temperature on my Hakko.  It fried the PCM2707, but it was h*ll figuring that out.
> ...


 
  
 I only mentioned it because you were asking about the PCM2707.  Remember that I said in my case, *all the voltages were dead on *(and there are many on the PupDAC)* - *it just wouldn't connect without a PC USB-connect error, no matter what I tried.
  
 Yours seems to be a true short somewhere with the voltages off and the tremendous heating.


----------



## KimLaroux

Okay. Is there a netlist already available for this board? I'd make one but since I have no clue what it looks like I wouldn't know where to start.
  
 I'll use the scans on the website as a starting point to make a continuity check. It gives me an idea of what's connected to what, though the vias makes it confusing for a newbie like me.


----------



## KimLaroux

In the meantime, here's the promised pictures:
  

  

  

  

  
 Don't mind the cut trace by C10. I did that to figure if the problem was on the PCM or DAC chip. It seems to be a problem with the PCM chip, as opening that circuit didn't change anything.


----------



## Avro_Arrow

It looks like a picture perfect (pun intended) soldering job.

 Dis-mount L3 and see if U2 functions normally.
 If so, replace U1.


----------



## tomb

avro_arrow said:


> It looks like a picture perfect (pun intended) soldering job.
> 
> Dis-mount L3 and see if U2 functions normally.
> If so, replace U1.


 
 Agreed.


----------



## KimLaroux

Yay well I spent the evening verifying that the continuity of the circuit matched what I read on the schematic. I didn't find anything out of order.
  
 I guess the next thing is to change the PCM chip.
  
 But uhm, how to I desolder such a chip without ruining the pcb? =X
  
 Also, the BOM lists the PCM2706 but I got a PCM2707. I'm guessing the 07 is simply an update to the 06 and any of the two would work on the Grub?


----------



## Avro_Arrow

kimlaroux said:


> But uhm, how to I desolder such a chip without ruining the pcb? =X


 

 There are a few different ways...
 The best is a hot air desoldering station.
  
 Failing that, cut all the leads from the chip and then
 just wipe off the leads with your soldering iron.
 Be careful not to cut the board.


----------



## Avro_Arrow

kimlaroux said:


> Also, the BOM lists the PCM2706 but I got a PCM2707. I'm guessing the 07 is simply an update to the 06 and any of the two would work on the Grub?


 

 They have some different features from each other, but for your purposes, they are interchangeable.


----------



## tomb

kimlaroux said:


> Yay well I spent the evening verifying that the continuity of the circuit matched what I read on the schematic. I didn't find anything out of order.
> 
> I guess the next thing is to change the PCM chip.
> 
> ...


 

 It will probably result in destruction of the chip, but I like to make a large solder blob over all the pins on one side of the chip. If you have a dental pick, you can lift the pins while the solder blob is melted on one side.  Do this by placing the pic in the space that exists between where the pins exit the chip and the pads on the PCB.  Repeat for the other four sides and you should have the chip removed.  Clean up with de-soldering braid and install the new chip as if it were a new PCB.
  
 Use whichever method sounds easiest for you.


----------



## wakibaki

When I'm replacing a SMT chip, I cut the defunct chip off the board, pin by pin, using a scalpel. You put the scalpel tip on top of the pin, as close as you can get it to the chip body and press hard, using one hand to hold the scalpel proper, and pressing with two fingers of the other hand further down the shaft. You hear a sharp _click_ as the pin parts and the scalpel blade drops down a fraction of a millimeter and comes to rest on a tiny ridge on the chip body. When you've worked your way through all the pins the chip will drop off. Then you pick up all the severed pins off the pads with a hot soldering iron and clean with braid.
  
 You have to be careful when doing this because you have to apply quite a lot of force, and you must take great care that the blade does not slip (or break) and damage either you or the board, but it's quick, positive and in my experience runs less risk of damaging a pad than prying at the pins.
  
 w 
  
 Oh, 2706 supports an external ROM. Missed that A_A had already said cut it off.


----------



## MisterX

> ~~But uhm, how to I desolder such a chip without ruining the pcb? =X


 
  
 Chip Quik.
  
  

  
 Or if you can stand to watch the videos from that EEVblog guy....
  
 http://www.youtube.com/watch?v=UmD7F0


----------



## Avro_Arrow

misterx said:


> Chip Quik.


 

 That stuff works great...the only problem is it's fifteen to twenty bucks for the kit and if you only have to remove one chip...


----------



## KimLaroux

wakibaki said:


> When I'm replacing a SMT chip, I cut the defunct chip off the board, pin by pin, using a scalpel. You put the scalpel tip on top of the pin, as close as you can get it to the chip body and press hard, using one hand to hold the scalpel proper, and pressing with two fingers of the other hand further down the shaft. You hear a sharp _click_ as the pin parts and the scalpel blade drops down a fraction of a millimeter and comes to rest on a tiny ridge on the chip body. When you've worked your way through all the pins the chip will drop off. Then you pick up all the severed pins off the pads with a hot soldering iron and clean with braid.
> 
> You have to be careful when doing this because you have to apply quite a lot of force, and you must take great care that the blade does not slip (or break) and damage either you or the board, but it's quick, positive and in my experience runs less risk of damaging a pad than prying at the pins.
> 
> ...


 
  
 Oh, that works well.
  
 I used my pocket knife, which I sharpen like a razor blade. I put the rounded edge on the row of pins, then pushed down while rocking the knife back and forth. It slowly dug into the row of pins and cut them from the body. I then wiped the pins away using my iron.
  
  
 But now it gets even weirder. I plugged the board in, without U1, and got the exact same message from dmesg:
  

```
[30536.808216] usb 6-1: new full-speed USB device number 2 using uhci_hcd [30536.921122] usb 6-1: device descriptor read/64, error -71 [30537.135224] usb 6-1: device descriptor read/64, error -71 [30537.338090] usb 6-1: new full-speed USB device number 3 using uhci_hcd [30537.450086] usb 6-1: device descriptor read/64, error -71 [30537.663111] usb 6-1: device descriptor read/64, error -71 [30537.866219] usb 6-1: new full-speed USB device number 4 using uhci_hcd [30538.275207] usb 6-1: device not accepting address 4, error -71 [30538.377220] usb 6-1: new full-speed USB device number 5 using uhci_hcd [30538.787205] usb 6-1: device not accepting address 5, error -71
```
  
 I mean, WHAT?!? How can my computer detect anything when there's no circuit to communicate with? 
	

	
	
		
		

		
		
	


	




 Anyways I got a bunch of PCM chips on order, we'll see when they arrive, I guess.

 Thanks everyone for your help.


----------



## DingoSmuggler

kimlaroux said:


> But now it gets even weirder. I plugged the board in, without U1, and got the exact same message from dmesg:
> 
> 
> ```
> ...


 
 That's probably a good sign - if the chip was shorting out it's supply voltage, then strange that it would also be able to communicate at all via USB.
 The USB host must just be picking up the fact there's a load on its power lines. The USB host actually controls the current available, it's not just hooked up to a 5V line in your PC. By default there should be 100mA available, high power USB devices need to negotiate with the host to get 500mA.


----------



## tomb

dingosmuggler said:


> kimlaroux said:
> 
> 
> > But now it gets even weirder. I plugged the board in, without U1, and got the exact same message from dmesg:
> ...


 

 Agreed.  It sounds like the USB PCM chip (2707) was unable to negotiate with the host - probably because it was shorted somewhere.  So, maybe replacing it will fix the problem.


----------



## KimLaroux

Well... this is depressing.
  
 I changed the PCM chip for a new one straight from TI. I was very careful not to burn it, lowering my iron temperature and taking breaks between pins to let the chip cool down.
  
 Plugging the DAC in, it's recognized, yay!
  

```
[ 218.102222] usb 5-1: new full-speed USB device number 3 using uhci_hcd [ 218.284426] usb 5-1: New USB device found, idVendor=08bb, idProduct=2707 [ 218.284439] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [ 218.284448] usb 5-1: Product: USB Audio DAC [ 218.284455] usb 5-1: Manufacturer: Burr-Brown from TI [ 218.292451] input: Burr-Brown from TI USB Audio DAC as /devices/pci0000:00/0000:00:1d.0/usb5/5-1/5-1:1.2/input/input14 [ 218.293105] hid-generic 0003:08BB:2707.0008: input,hidraw5: USB HID v1.00 Device [Burr-Brown from TI USB Audio DAC ] on usb-0000:00:1d.0-1/input2 [ 218.488522] usbcore: registered new interface driver snd-usb-audio
```
  
 But then a few seconds later...
  

```
[ 224.453080] hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling... [ 224.453088] usb 5-1: USB disconnect, device number 3 [ 224.674050] usb 5-1: new full-speed USB device number 4 using uhci_hcd [ 224.789058] usb 5-1: device descriptor read/64, error -71 [ 225.003031] usb 5-1: device descriptor read/64, error -71 [ 225.207040] usb 5-1: new full-speed USB device number 5 using uhci_hcd [ 225.320048] usb 5-1: device descriptor read/64, error -71 [ 225.535043] usb 5-1: device descriptor read/64, error -71 [ 225.739042] usb 5-1: new full-speed USB device number 6 using uhci_hcd [ 226.148029] usb 5-1: device not accepting address 6, error -71 [ 226.251027] usb 5-1: new full-speed USB device number 7 using uhci_hcd [ 226.659032] usb 5-1: device not accepting address 7, error -71 [ 226.659056] hub 5-0:1.0: unable to enumerate USB device on port 1
```
  
 This was using a short cable without a ferite, straight into my laptop. I then tried a longer cable with a ferite, same thing. Then I tried using the DAC trough my external, powered HUB:
  

```
[ 1137.412388] usb 2-4.1.4: new low-speed USB device number 15 using ehci-pci [ 1137.493601] usb 2-4.1.4: device descriptor read/64, error -71 [ 1137.673604] usb 2-4.1.4: device descriptor read/64, error -71 [ 1138.592717] hub 2-4.1:1.0: Cannot enable port 4. Maybe the USB cable is bad? [ 1139.412605] hub 2-4.1:1.0: Cannot enable port 4. Maybe the USB cable is bad? [ 1140.229697] hub 2-4.1:1.0: Cannot enable port 4. Maybe the USB cable is bad? [ 1140.230914] hub 2-4.1:1.0: unable to enumerate USB device on port 4
```
  
  
 *sighs*
  
 Lemme try disabling every wireless communication on my desk, turn my dac and amp off, disconnect every usb device... and try again.


----------



## Avro_Arrow

How are the voltages?

 Sounds like something may be overheating causing the power
 to cycle on and off.
  
 The fact that the laptop was able to "see" the PCM means
 it was working properly at first...


----------



## KimLaroux

avro_arrow said:


> How are the voltages?
> 
> Sounds like something may be overheating causing the power
> to cycle on and off.
> ...


 
  
 VDD sits at 3.32V. The vreg doesn't have time to get warm before the DAC looses connection, as it's only a second or two.
  
 Googling the error message, it seems crippingly common on Linux. I'll try the DAC on a different computer when I get the chance.


----------



## Avro_Arrow

kimlaroux said:


> I'll try the DAC on a different computer when I get the chance.


 
  
  
 That would have been my next suggestion too.


----------



## wakibaki

Years ago I was working on a military handheld radio in development in the lab. It was a bleeding-edge spread-spectrum type, a double-superhet. One of the local oscillators would not run. It had tiny components like grains of sugar, 0402 I think.

I replaced every component in the LO, first one-by-one, then in bunches. I could not get the oscillator to start.

Eventually I took a working radio and transplanted the LO components to the faulty radio in entirety. I was convinced the LO would start, but it wouldn't. I took all the components and put them back in the radio they came from, and they worked. There was a high resistance short between 2 tracks on the faulty board, due to some kind if inclusion, some impurity in the PCB.

Now, I'm not saying that's what's going on here, but it's an example of how obscure a fault can be.

w


----------



## KimLaroux

Well, pout.
  
 I tried my GrubDAC on my friend's computer and it works fine. She has an Alienware with SuperSpeed USB ports, running OpenSUSE.
  
 The DAC is detected and installed the same way as on my system, only it works an doesn't crash the main USB hub.
  
 I don't know what to do from here. I guess my 7 years old laptop needs a refresh. What's the status on using the GrubDAC from netbooks? A netbook makes an attractive option to use as transportable system with a GrubDAC+Carrie, but I sort of doubt their USB ports would be any better than my current laptop's.


----------



## tomb

kimlaroux said:


> Well, pout.
> 
> I tried my GrubDAC on my friend's computer and it works fine. She has an Alienware with SuperSpeed USB ports, running OpenSUSE.
> 
> ...


 

 I've got 2 netbooks.  None has given a problem with the GrubDAC.  Granted, I just discovered recently that they were absolutely the wrong choice to use for demonstrating USB-powered DACs, but they never did not work.


----------



## KimLaroux

tomb said:


> I've got 2 netbooks.  None has given a problem with the GrubDAC.  Granted, I just discovered recently that they were absolutely the wrong choice to use for demonstrating USB-powered DACs, but they never did not work.


 
  
 Coud you ellaborate on why they are bad choices?


----------



## tomb

kimlaroux said:


> tomb said:
> 
> 
> > I've got 2 netbooks.  None has given a problem with the GrubDAC.  Granted, I just discovered recently that they were absolutely the wrong choice to use for demonstrating USB-powered DACs, but they never did not work.
> ...


 
 I'm sorry ... I sometimes expect someone to get the context when they've been following all the pertinent threads, etc. 
	

	
	
		
		

		
			





 Yes - they are BAD choices because the DoodleBug proved they are crap when it comes to USB power/etc.  It's the same thing I've found for just about any laptop - including docking stations.  (The trouble with docking stations is that they are fed by the same power adapter as the laptop.)


----------



## wakibaki

kimlaroux said:


> Well, pout.
> 
> I tried my GrubDAC on my friend's computer and it works fine. She has an Alienware with SuperSpeed USB ports, running OpenSUSE.
> 
> The DAC is detected and installed the same way as on my system, only it works an doesn't crash the main USB hub.




Excellent. We have to rate that as a successful build.

w


----------



## iwuk78

Hi All,
  
 I feel a little out of my depth here (ok a lot). I got my GrubDAC built today. It was my first time soldering surface mount stuff, so it is a little messy, but I can't see any obvious bridges. When I plug it in, Windows sees it and the led comes on, but I'm not getting any sound out of it. I have checked 0v to 3.3v and get nothing there. Actually I don't seem to get anything from 0v to 5v either. I just re-flowed all of the surface mount stuff, but am still not getting any signal out. One thing I accidentally did, was to cut the "bridges" between the pins of the PCM2706 before realizing that they were meant to be there. Doh! So I created my own solder bridges there in the hope that it would suffice. Bad idea? I also did initially get solder from the pads to the top of the oscillator, but I have since cleaned that up. There is still some solder in the little groove between the top and the copper bit, does that matter? 
  
 I feel like I'm almost there, but can't quite make it over the line!
  
 Any help would be appreciated 
  
 Thanks,
 Ian.


----------



## Avro_Arrow

iwuk78 said:


> Hi All,
> 
> I feel a little out of my depth here (ok a lot). I got my GrubDAC built today. It was my first time soldering surface mount stuff, so it is a little messy, but I can't see any obvious bridges. When I plug it in, Windows sees it and the led comes on, but I'm not getting any sound out of it. I have checked 0v to 3.3v and get nothing there. Actually I don't seem to get anything from 0v to 5v either. I just re-flowed all of the surface mount stuff, but am still not getting any signal out. One thing I accidentally did, was to cut the "bridges" between the pins of the PCM2706 before realizing that they were meant to be there. Doh! So I created my own solder bridges there in the hope that it would suffice. Bad idea? I also did initially get solder from the pads to the top of the oscillator, but I have since cleaned that up. There is still some solder in the little groove between the top and the copper bit, does that matter?
> 
> ...


 

 Well, the first thing we always ask is for good, clear, close-up pictures.
  
 Any soldering mistakes around the oscillator will result in no sound. Make sure the soldering
 there is very clean (no solder is where it shouldn't be). It sounds like that may be part of the
 problem.
 When you say "windows sees it", do you mean it is detected and installed properly?
 That can be a good clue as to where to look for a problem.
 Also, it sounds like you are telling us that you get no voltage at the 5 volt and 3.3 volt
 test points. The LED being lit suggests at least the 5 volts is working.
 Please re-check the test points.
  
 Good luck!


----------



## tomb

avro_arrow said:


> iwuk78 said:
> 
> 
> > Hi All,
> ...


 

 Ditto. 
	

	
	
		
		

		
		
	


	




 
  
 Also, the way the GrubDAC is designed, the USB connection is through the PCM2706/7 portion of the circuit.  I believe it's quite possible to get a good USB connection, but then no sound from the Wolfson DAC portion of the circuit.


----------



## iwuk78

avro_arrow said:


> Well, the first thing we always ask is for good, clear, close-up pictures.
> 
> Any soldering mistakes around the oscillator will result in no sound. Make sure the soldering
> there is very clean (no solder is where it shouldn't be). It sounds like that may be part of the
> ...


 
  
 Yes, I meant it is detected and installed in windows. I can select it as an output and send audio to it.
 I took off c1 and checked all around the oscillator, none of the corners have a connection between the pads and the top. 
  
 I guess maybe I'm checking the test points wrong. I'm putting a probe on the 0v lead, and the other in the 3v3 hole, and a probe on the 5v lead and 0v lead. Is that correct? I get 0v for both of those tests.
  
 Here are some photos... there was what looked like a possible bridge at the bottom right of the PCM, you can see in the back lit pic. I have cleaned that up, but still get nothing. 
http://www.w2solutions.com/grubdac.jpg
  
 Thanks for the help! I'm determined to get this going!


----------



## iwuk78

Apparently I can't attach images or post links... So I guess I'll cheat. This may land up posted twice so sorry about that!
  
 Yes I meant that Windows detects and installs the grubdac correctly. I can select it as an audio output.
  
 I pulled off c1 and checked the oscillator, there are no connections between any of the pads and the top.
  
 I take it back about 3v3 and 5v. I don't know what I did last night, but both are reading fine today. 
  
 Here is a "link" to my pic www DOT w2solutions DOT com/grubdac DOT jpg 
  
 Thanks for the help!


----------



## Avro_Arrow

Here is the picture:


----------



## iwuk78

Thanks!


----------



## Avro_Arrow

As far as I can see, despite the soldering job, only pins 1, 2 and 3 on the PCM2706

 seem to be problematic. The fact that it is recognized by the computer suggests
 that the problem lies with either the I2S lines from the PCM to the WM8524, or
 with the WM8524.
  
 It looks like your soldering iron is too cold or there is not enough flux.
 What kind of solder and soldering iron do you use?


----------



## iwuk78

I'm using a Hakko 936. I think it is the solder. I had thought it was flux core, but I think it's actually not, and I only had a "no clean" flux pen lying around that didn't seem to help a great deal. It's fine for through hole, but I guess surface mount stuff is a little more picky... I really should have waited and got some decent solder (it is also way too thick), but I was a little too eager to get going. I regret that now! Lesson learned.
  
 I have re-flowed the WM8524, but still no go. I wonder if I may have fried it. Is there a way to determine that, short of just replacing it?
  
 What kind of solder do folks recommend for this kind of work?
  
 Thanks for the help.


----------



## Avro_Arrow

This is the solder I use...it's nothing special but it gives me good results:
  
  


 I also use Solder Paste for SMD work.
 I have my iron set for 500 - 550 F.
  
 If you have access to an oscilloscope, you could check that the WM8524
 is getting the correct signals, but short of that, replacing it is the next
 option.
  
 Before you go to that extreme, do a continuity check.
 Using the schematic, check that the pins on the PCM are
 actually connected to the pins on the WM and aren't shorted
 to anything else along the way. You can also check that
 the other pins also go to where they should and are not
 open or short.
  
 Good luck!


----------



## Avro_Arrow

Here is how the soldering job should look:
  


 Sorry about the lint...


----------



## iwuk78

You got it! I checked continuity between the PCM and WM, which was fine. I then checked between the top of the pins on the WM and the pads and found one that was not soldered (looked like it was, even with magnifier). Beeped only when applying pressure. Resoldered it and BAM! Sound! 
  
 Thank you for taking the time to look at this, it is much appreciated! 
  
 I'm going to go and get ice cream to celebrate haha. 
  
 Made my day 
  
 Thanks for the pics too. I think I'll definitely pick up some better solder before attempting any smd work again. The stuff I used needed the iron at about 600f to flow properly.


----------



## Avro_Arrow

iwuk78 said:


> Thank you for taking the time to look at this, it is much appreciated!


 
  
 Your welcome, I hope you enjoy it!


----------



## LosNir

Hi Guys! Another one with a no-sound problem right here!

Here are some notes:

1. The GrubDAC is detected fine by Windows and shows up on playback devices. No instabilities.
2. The LED lights up.
3. 3.3V Test point shows stable ~3.29V.
4. 5V Across C5. 3.3V Across C1 & C15.

I've reflowed U1 and U3 and cleaned the board several times, with no luck.

Any ideas?



Thanks.


----------



## Avro_Arrow

Can you check from ground to pin 2 on the wolfson?

 There should be -3.3 volts.
  
 As far as I can tell from the pictures, soldering looks good.


----------



## LosNir

I managed to get it working 

I didn't do anything special actually.
I just took it to take some high-magnification pictures using my USB Microscope, and then I checked for continuity across some of the Wolfson's pins, and then it started working.

It might be the multimeter leads that scrapped of some solder that bridged two pins.


----------



## vonchap

I put my GrubDAC inside my Objective 2 (instead of an ODAC) and soldered the line out directly to the O2 board. I would like to add a RCA out from my GrubDAC. Can I simply solder it to the existing line out wires?


----------



## tomb

vonchap said:


> I put my GrubDAC inside my Objective 2 (instead of an ODAC) and soldered the line out directly to the O2 board. I would like to add a RCA out from my GrubDAC. Can I simply solder it to the existing line out wires?


 

 I think the problem is, will you have both outputs connected to anything at the same time?  I'm not certain about the O2, because it deviates from accepted practice in the location of the volume pot in the circuit.  However, if you connected both outputs to amps whose volume pots are at the input of the amplifier circuit (typical), then the static resistive load of the two pots will reduce the output of the DAC - perhaps to an unacceptable level.  When I say "static," I mean even with the amp off - the resistive load of the volume pot is still there.
  
 What you want to do would work better with a switch, I think.  A DPDT switching the signal leads with a shared ground should work.  That way, the DAC only sees one load at a time.


----------



## vonchap

> Originally Posted by *tomb *
> 
> What you want to do would work better with a switch, I think.  A DPDT switching the signal leads with a shared ground should work.  That way, the DAC only sees one load at a time.


 
  


 Thank you! I will try that. By the way, I really love the GrubDAC. It works flawlessly for me and sounds great! I A/B it with the ODAC and couldn't hear a difference.


----------



## WK3K

Hi All,
  
 After a few days of fiddling with the GrubDac (Missed a few pins on U1 and U3, needed to reflow a point on X1) I finally got sound. Unfortunately it was super static-y and distorted, like a radio station that's not quite in focus. I noticed there was still a lot of flux on the board, so I scrubbed it down with 91% isopropyl alcohol, plugged it back in, and now no sounds. Sad dude.
  
 I get 3.3v at that test point and 5.1v at the 5v point. LED does come on and it is recognized by the computer (Mac OSX). I will post pictures as soon as my account is allowed to do that, but it does not look like i have any bridges on the chips.
  
 UPDATE: Just plugged it in again this morning, played beautifully for about 30 seconds, then started to get progressively static-y again and now nothing. Just when I thought there was HOPE!
  
  
 Thoughts?

 Witold


----------



## tomb

1. You assembled it correctly. The fact that you got sounds at different points proves that.

2. You still have some dodgy soldering joints somewhere, most likely on the usb or dac chip. The fact that it works, doesn't work, or has static and pops all confirm this.


----------



## WK3K

Thanks Tom. I guess the project for this evening will be reflowing the chips. I haven't messed with the mini-USB either, so I'll give that a go. Again, I'll get some pictures up as soon as my account is allowed access for that.
  
 Edit: I tried reflowing U1 and U3 again. It started out playing a little more consistently, but still like a radio stuck between stations. I also have no volume control at the source and the volume seems to fluctuate up and down. Pushing gently on the wolfson chip with my finger while it's playing stops everything completely. It will also just stop playing on it's own after 30 seconds to a minute. 
  
 I still see no bridges and have tried resoldering all the pins, so I really don't know what else to try at this point. Just to be safe I've also reflowed everything else. No change.
  
 Best,

 Witold


----------



## WK3K

Just saw this in the PupDac build notes:
  
 "One thing to be aware of - the latest chips from TI use a different case material and is actually hygroscopic.  The pins are sealed at the case body, but the body itself may absorb moisture.  This is nothing to worry about except when you've rinsed at the end and you're ready to plug it in - don't.  Wait for a few hours, use a hair dryer, put the PCB out in the sun, etc. to make certain that things are dry under and inside the chips.  Otherwise, you'll drive yourself crazy trying to figure out why your DAC doesn't work or seems to de-activate itself every few minutes.
	

	
	
		
		

		
			





"
  
 Will that apply to GrubDac components as well?


----------



## tomb

wk3k said:


> Just saw this in the PupDac build notes:
> 
> "One thing to be aware of - the latest chips from TI use a different case material and is actually hygroscopic.  The pins are sealed at the case body, but the body itself may absorb moisture.  This is nothing to worry about except when you've rinsed at the end and you're ready to plug it in - don't.  Wait for a few hours, use a hair dryer, put the PCB out in the sun, etc. to make certain that things are dry under and inside the chips.  Otherwise, you'll drive yourself crazy trying to figure out why your DAC doesn't work or seems to de-activate itself every few minutes.
> 
> ...


 

 It's possible.  There's certainly something going on with the DAC chip if it stops playing when pressed.  Unlike most scenarios, where pressing might put a dodgy connection into good contact, perhaps there's a bridge underneath the chip and/or pins that comes into contact when pressed.  The fact that the analog volume goes up and down, stops on its own, etc. is also an indication.
  
 The DAC chip on the GrubDAC is fairly close to an SOIC opamp in terms of difficulty.  Perhaps it can be removed, the PCB cleaned up, then soldered again.  The Wolfson DAC on the GrubDAC is pretty cheap, too - so a full replacement is not a lot of trouble, either.


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## WK3K

Thanks TomB. I'll try to remove it and clean everything up over the weekend. I'll be in contact with you about order a new chip as well. 
  
 Any tips for removing the chip? Just flood a whole side with solder, heat it up, and pry with an exacto knife?
  
 W


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## tomb

Yes - carefully, but exactly right.


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## triple-u

Hi all,
  
 I'm having trouble with getting my GrubDAC working. It's recognized by my computer and the test points are good. There doesn't appear to be any bridges between pins. I'm not getting sound though.
  
 I've tested for bridges at all the pins, I've tested continuity between the Wolfson and the PCM, and various other points and they all seem fine. I do have a second working GrubDAC and compared the two and haven't found any differences. Any other suggestions on what I can test? Is there a way to test whether the Wolfson is burned out or not?
  
 Thanks


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## tomb

triple-u said:


> Hi all,
> 
> I'm having trouble with getting my GrubDAC working. It's recognized by my computer and the test points are good. There doesn't appear to be any bridges between pins. I'm not getting sound though.
> 
> ...


 

 I would try re-flowing the DAC chip and see if it makes any difference.  If your PC recognizes the GrubDAC and the test points are fine, then the problem is with the DAC chip or your output connections.


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## triple-u

tomb said:


> I would try re-flowing the DAC chip and see if it makes any difference.  If your PC recognizes the GrubDAC and the test points are fine, then the problem is with the DAC chip or your output connections.


 
 I tried re-flowing the chip and it didn't work. Thought maybe there wasn't enough solder so I tried re-flowing a second time. Stupid mistake. Ended up bridging a few pins and couldn't clean it up. Used solder wick and after an hour struggling with it burned the PCB and destroyed the pins. Don't think it's recoverable now.
  
 Oh well...


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## tomb

triple-u said:


> tomb said:
> 
> 
> > I would try re-flowing the DAC chip and see if it makes any difference.  If your PC recognizes the GrubDAC and the test points are fine, then the problem is with the DAC chip or your output connections.
> ...


 

 If you burned the PCB, then most likely your iron is too hot and the chip was damaged from the first soldering.
  
 Send me your address (or confirm it) and I'll send you another Wolfson chip.


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## triple-u

tomb said:


> If you burned the PCB, then most likely your iron is too hot and the chip was damaged from the first soldering.
> 
> Send me your address (or confirm it) and I'll send you another Wolfson chip.


 
 Thanks for the offer, but I checked closely and a couple of the pads were also knocked off the PCB. It's going to be a much tougher job. It might be better to start over from scratch. I did order an extra kit, because I was expecting myself to make mistakes my first time soldering surface mounts.


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## tomb

triple-u said:


> tomb said:
> 
> 
> > If you burned the PCB, then most likely your iron is too hot and the chip was damaged from the first soldering.
> ...


 

 Sorry to hear that.  Let us know how we can help with the next one.


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## juswyq

i just built my first grubdac with a pcm2707 - but the windows 7 main volume control doesn't work. I use this a lot so it is a big inconvenience. I realise that I could simply change the individual application volume control but I prefer having a working master volume control.
  
 I checked TI's website and realised that there are newer variants of the chip - PCM2706C and PCM2707. I am considering desoldering the chip and changing to PCM2706/7C - will this solve the volume control issue?


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## tomb

It should, but you may be blazing the trail, first. Let us know if it works.

Just to be clear - the problem is with Microsoft's Windows 7, not TI. At least TI developed an entirely new chip revision to try and fix it.


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## juswyq

I am confused about this issue though - I read the documents for the "C" revision of the PCM2706/7 and it seems like they only changed the behaviour of the volume control (i.e. how the volume changes with the win7 volume slider); the "C" variant doesn't seem to *enable *the volume control. 
  
 The document is here: http://www.ti.com/lit/an/sbfa019/sbfa019.pdf
  
 I'm trying to isolate the problem: is my non-functioning master volume control due to me using PCM2707 instead of PCM2706, or is it because I'm using the non-C revision?
  
 Desoldering and resoldering the IC chip will be a nasty job...


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## tomb

I can't guarantee anything, but this has been a long standing issue with Win7. There is no difference with respect to 2707 or 2706 for this issue. The 'C' variant is supposed to address it.

As stated however, I can't guarantee anything about your personal setup. I just thought that maybe you could confirm it for all of us.

If you're afraid to mess with it, I can certainly understand.


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## patchoncas

Well, this is a first. Never had any sort of problem with SMD soldering before.
 The board looks fine, there are no shorts anywhere, I've tested every pn on the ICs and they are soldered properly. The electrolytic caps are soldered right. PC feeds 5.18V into the DAC. The LED lights up as it should.
  
 Problem is, the 3.3V test point gives 0.25-0.30V. This would seem like a cold solder joint, but I've reflown every pin on the regulator, and every component besides it (the ferrite and the three capacitors, who give stability to the chip if I'm not wrong). I've even changed the regulator for another one, because I thought the first one was dead on arrival or killed by heat or something. But no.
  
 What could it be? Pictures in the gallery.
  
http://imgur.com/a/KfUkh
  
 EDIT: also removed the ferrite between the reg and the other ICs to check if there was a short somewhere along that way, and nothing. The circuit seems okay, it's jut the region of the regulator.


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## Avro_Arrow

Is there 5 volts at the input to U2?
 If there is, remove C7, C8 and L3.
 Is there a short under C7 or C8.
 Is there 3v3 from U2 now?
 If no, replace U2.
 Is it working now?
 If yes, re-install C7, C8 and L3


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## patchoncas

1. Yes
 2. No shorts
 3. No, but I reflowed it (yet again) and now it gives me an oscillating value, between 2.8 and 3.4. Looking good.
 4. Soldered the caps: voltage drops to 0.5 or so again. What the hell? I guess I have bad caps.
  
 Is it possible that I have received a bad batch of regulators?


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## Avro_Arrow

Which cap causes it to stop working?


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## Avro_Arrow

C8 is the noise reduction cap for the regulators internal reference.
 C7 is an input bypass cap in parallel with the electrolytic on the
 other side of the board.
  
 If either of these were to cause a problem, it would be C8.
  
 What about C14...it is directly on the output of the regulator.
 Have you removed and checked it?


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## tomb

Thanks for the support, Avro!  I've been awfully busy lately and unable to check on things as often as I should.


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## juswyq

juswyq said:


> I am confused about this issue though - I read the documents for the "C" revision of the PCM2706/7 and it seems like they only changed the behaviour of the volume control (i.e. how the volume changes with the win7 volume slider); the "C" variant doesn't seem to *enable *the volume control.
> 
> The document is here: http://www.ti.com/lit/an/sbfa019/sbfa019.pdf
> 
> ...


 
  


tomb said:


> I can't guarantee anything, but this has been a long standing issue with Win7. There is no difference with respect to 2707 or 2706 for this issue. The 'C' variant is supposed to address it.
> 
> As stated however, I can't guarantee anything about your personal setup. I just thought that maybe you could confirm it for all of us.
> 
> If you're afraid to mess with it, I can certainly understand.


 
  
 Tragedy! I tried to desolder the PCM2707 chip and but burnt some solder pads off the board. Now the board is useless and I have wasted the other parts that are already soldered on 
  
 I then built a Pupdac with a PCM2707C after much effort (the pcm1794 is a tough job). Alas, the volume control in windows 7 is still not working.
  
 I am now contemplating whether to order another grubdac and pupdac board to do a better job.
  
 Thank you for your help Tom!


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## KimLaroux

So... I bought a new desktop PC with Windows 7 and it doesn't even detect my GrubDAC... this is sad. =(
 
I'm clueless when it comes to Windows. How do I go about debugging this?


edit: I booted on a fedora usb stick and dmesg floods me with this:


[ 209.924022] hub 6-0:1.0: connect-debounce failed, port 2 disabled
[ 212.126019] hub 6-0:1.0: connect-debounce failed, port 2 disabled
[ 214.330018] hub 6-0:1.0: connect-debounce failed, port 2 disabled
[ 216.535020] hub 6-0:1.0: connect-debounce failed, port 2 disabled


This project is getting sadder every time I try to make it work. I'm out of ideas here. =(


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## Avro_Arrow

It should have recognized it right away...even if just to give you an error.
 It's as if it didn't see it at all.
 I'm sure you tried a different cable and port...
  
 Is the DAC getting power?


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## KimLaroux

The DAC powers fine...

I think the problem is with the Carrie, so I'll be moving this discussion over there. Here's why I think so:

I added a power switch between the carrie and the dac. When I plug the DAC in with the switch open, the DAC is recognized:

 1460.483019] usb 6-2: new full-speed USB device number 52 using uhci_hcd
[ 1460.669007] usb 6-2: New USB device found, idVendor=08bb, idProduct=2707
[ 1460.669011] usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1460.669014] usb 6-2: Product: USB Audio DAC 
[ 1460.669017] usb 6-2: Manufacturer: Burr-Brown from TI 
[ 1460.701071] input: Burr-Brown from TI USB Audio DAC as /devices/pci0000:00/0000:00:1d.0/usb6/6-2/6-2:1.2/input/input19
[ 1460.701346] hid-generic 0003:08BB:2707.0009: input,hidraw5: USB HID v1.00 Device [Burr-Brown from TI USB Audio DAC ] on usb-0000:00:1d.0-2/input2

But the moment I close the switch to power the carrie...

[ 1528.953037] hub 6-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[ 1528.953045] usb 6-2: USB disconnect, device number 52
[ 1531.042021] hub 6-0:1.0: connect-debounce failed, port 2 disabled
[ 1533.246020] hub 6-0:1.0: connect-debounce failed, port 2 disabled

I'm thinking my Carrie+GrubDAC combo is pulling too much power off the usb port.


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## Wisor

Hey,
  
 Is it possible to order this dac somewhere in europe ?


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## tomb

wisor said:


> Hey,
> 
> Is it possible to order this dac somewhere in europe ?




No.


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## Zigis

tomb said:


> No.


 
 However international post services still work great.


----------

