# 'noodle' dac (ebay special)



## adamus

I wanted to build a cheap dac for my father to use between his airport express and hifi. 

 I bought this from ebay for £30 delivered:






 Spdif / toslink in, Digital / Analog converters: CS4397 24bit 192khz DAC Digital receiver : Crystal CS8416

 currently house in a cardboard box (but is going in a hifi2000 case). 

 FOR THE MONEY: This sounds seriously good standard. Drop an opa2107 (poor mans 627) in it and it sounds brilliant. Nice rich sound, darkish but detailed. Organic highs. I doubt this will compete with your stello or benchmark, but i wouldnt be suprised if it caught a few people out. 

 Nest step? get shot of the coupling caps and replace with a nice film cap. Replace the electrolytics with something better like pana FC's. 

 In comparison with my alien dac? Its more natural, more body to male vocals, seems to have more slam and generally sounds 'bigger / more bodied'. I wont say its better, because i use my alien for portability, and this is clearly not portable - they serve different functions. However, on my home rig currently this is getting all the air time. 

 when i remove the stock coupling caps and replace with something like an auricap or claritycap i suspect it will move to new level.


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## gurusan

I was looking at that kit but chose the Alien as I want a USB input....


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## adamus

gurusan - where in oxford? I live in oxford. what have you built.


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## FS2

Just happened to look in this thread and:
 You guys too? I'm here as well. All my builds are barely off the ground though...


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## gurusan

I live in North Oxford...not built anything yet..I'm a noob!






 have an alien DAC kit on the way though along with a Little Dot 2 and HD 595 cans ...this is my first proper setup after a few years of a XFI which I modded and HD 205s

 Do you know if there's any way to add a USB input to that ebay special DAC?


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## adamus

you could get a cheap usb to spdif and do it that way. but you would then have two conversions, and a lot of the cheaper usb converters dont get good reviews.


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## adamus

actually, looking at the datasheet you could build a usb > I2s converter (search these boards) and maybe try. Anyone know if this would work. 

 Connect serial data to sdata pin
 Connect bit clock to sclk pin
 Connect word select to lrclk pin
 connect ground to s ground pin


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## dgbiker1

Please tell me that was a kit and that somebody isn't just selling DACs on eBay in cardboard boxes


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## adamus

A kit.... but you have to admit, the box looks 'tight'.


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## fordgtlover

I bought ine recently. I've only had a few hours listening, but it seems pretty god. I have it connected to the SPDIF out directly out of my PC (with a DIY SPDIF adapter), and it still sounds pretty good. It is very revealing.

 I've jus bought a HagUSB to simplify the connection. It will be intereting to compare the current SPDIF with the USB.

 And, of course, the price of these units is definitely right


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## 2162

Blue tack, you serious? 

















 Looks great though =)


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## adamus

yes! bluetak damps and vibration and improves the optical transmission. I use it in all my builds. Cocopops provide the bext casing material, they really improve the 'pop' and 'crackle' the dac puts out. Due to the lack of cocopops housing matieal i went for the next best thing, 'nicky clarke travel hair dryer'. Whilst not in the same league as the breakfast cereal, it does provide a nice 'warm but dry', you could almost say 'airey' sound. 

 Just ordered my modushop (hifi 2000) cases. 1 for the dac and one for a bijou amp that i will build next.


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## adamus

ok, serious question now.

 I found this for a potential mod






 basically all coupling caps bypassed and thentwo better coupling caps in place. Seems very sensible. 

 However, the chap recommends 3 to 10 uf film caps. Are these not too big? surely the impedance this thing is going to see is the 50k pot in my amp? most preamps will have this order of this sort of impedance - thus wont i need something around 0.47uf???


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## error401

Yep, you're right.


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## keiths

OK, so I've bought one of these and want to tweak it. 

 I've replaced the op-amp with an OPA2132PA (the only dual op-amp I had lying around) which is a noticeable improvement over the stock one, but intend to get an LM4562NA (data sheet here: LM4562 - Dual High Performance, High Fidelity Audio Operational Amplifier ) unless anyone knows any good reason not to.

 In the photo Adamus posted a couple of posts ago, the coupling caps have been removed and replaced with links, but there appear to be lots of other changes too. I'm I right in thinking I only need to remove the 6 electrolytics that I've indicated in the photo below, replace with links and add a 0.47uF film cap plus a series resistor to each channel's ouput? 






 How do I decide what value of resistor to use? The dac will be connected to my Starving Student which has a 50k pot and also to my Arcam amp which has an input impedance of 22k ohms?


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## adamus

the chap that did the mods originally suggesta resistor is needed to load the dac. 

 I just dont see why this is needed, inline with that you will have 50k, what difference a 68k resistor makes i do not know.


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## HeadphoneAddict

Is your fire insurance up to date?


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## keiths

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Is your fire insurance up to date?_

 

Please explain....


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## HeadphoneAddict

Quote:


  Originally Posted by *keiths* /img/forum/go_quote.gif 
_Please explain....
	

	
	
		
		

		
		
	


	





_

 

I'd be afraid the box would catch fire. Maybe I'm wrong, just looks scary.


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## keiths

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I'd be afraid the box would catch fire. Maybe I'm wrong, just looks scary._

 

It's going in a propper case. It was only connected up in the box for a quick test!

 I was worried that you were suggesting that the capacitor mods would make it liable to catch fire!


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## adamus

for all those worried about my cardboard box (sorry about the crappy phone pics) :






 its now house in the top unit.


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## fordgtlover

Have you done any of the mods to it?


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## adamus

re,oved the signal electrolytics, replaced with obbilgato film. changed the opamp to a opa2107. sounds lovely.


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## fordgtlover

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_re,oved the signal electrolytics, replaced with obbilgato film. changed the opamp to a opa2107. sounds lovely._

 

Do you have a picture of your mods?


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## adamus

same as the guide picture i showed you. 

 except i have obbligatos in the signal chain. I am confused by the apparant need for the resistors. I can only assume its for when nothing is connected, otherwise putting a 68r resistor in line with a pot (50k!) cant make any difference. Eitherway, i didnt put the resistor in line and havent experienced any issues yet.


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## 00940

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I am confused by the apparant need for the resistors. I can only assume its for when nothing is connected, otherwise putting a 68r resistor in line with a pot (50k!) cant make any difference. Eitherway, i didnt put the resistor in line and havent experienced any issues yet._

 

Think one second about it. What happens if you short the output to ground, with and without the resistors ?


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## adamus

cap will dump resisdual charge back into g. 

 why would i short the input though? if its just left pulgged into my amp.


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## 00940

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_cap will dump resisdual charge back into g. 

 why would i short the input though? if its just left pulgged into my amp._

 

tss, tss, you have to think like a DAC builder: sooner or later, one of your customer will short the output, while the dac is playing. The opamp will try to push 2Vrms into a short. It could fry and the customer won't be happy. If you put something like a 100 to 1k resistor in line with the output, the opamp will survive easily and the sound quality won't suffer at all. No need for very low output impedance here.

 As a guess, the resistors protecting the output were R28 and R29. On the pic you show, the modder removed those (among others). He thus had to put some new resistors to protect the output against a short.


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## keiths

Quote:


  Originally Posted by *00940* /img/forum/go_quote.gif 
_As a guess, the resistors protecting the output were R28 and R29. On the pic you show, the modder removed those (among others). He thus had to put some new resistors to protect the output against a short._

 

From the schematic supplied with the DAC, R28 is a 100K resistor connecting the LOUT with ground whilst R29 is a 100K resistor connecting ROUT with ground. 

 I'm currently modding my DAC and have only removed the 6 electrolytic capacitors (replaced with wire links) and added 0.47uF film caps to the outputs - I haven't touched R28 and R29 - so do I need the extra resistors?


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## 00940

Bad guess thus 
	

	
	
		
		

		
		
	


	




 R28 and R29 are thus simple pulldown resistors, to avoid "pops".

 Still, all the rest stays true. You really need a resistor in serie with the output to be safe. There might be some on the pcb already ?


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## adamus

can you post the schematic keiths


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## keiths

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_can you post the schematic keiths_

 

Yep - but it'll be tomorrow morning (and will be a poor quality scan of a poor quality print)


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## keiths

DAC Schematic


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## 00940

ok now, all is clear. The designer has put an analog multiplexer at the output (an electronic switch). It mutes the dac when the spdif isn't locked properly.

 Since the multiplexer switch has a resistance in between 120 and 400 ohms when closed, no need for more resistors in serie.

 This said, I've never been fond of multiplexer... I'd replace it by a good old mechanical relay.


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## adamus

yes, i am with you on that. No resistors needed. 

 Do you see a problem with removing the caps before the opamp stage? The opamp shouldnt mind a bit of dc...should it?


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## keiths

Found this photo in the same Photobucket album as the initial one Adamus posted showing the capacitor mods. Am I right in thinking he has taken the multiplexor out of circuit with the two solder blobs (presumably for sound-quality reasons) and hence the requirement for the additional series resistors?


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## adamus

seems logical. although if spdif looses lock then i dont know what noise you would hear, may not be nice.


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## 00940

keiths: seems right.

 Adamus: you can remove c27-28-30-31 without problem. In fact, you can probably do without any coupling caps whatsoever: the DC offset is common to the balanced outputs and the opamp will suppress it (it's a balanced receiver...). As an experiment, bypass c27-28-30-31 and check how much offset you have at the output pins of the opamp. If the resistors around it are well matched, it should be close to 0mV.

 It would be interesting (but not easy) to replace all the small caps serving as filter around the opamp: C32-33-34-35-36-37-38-39 (it's a bit difficult to read). On the pic of a modded dac, the modder started to do it : look at the yellow caps. You'd want at least NPO/C0G ceramic caps there. Best would be polystyrene or silver mica, but it's gonna be a tough fit.


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## keiths

Quote:


  Originally Posted by *00940* /img/forum/go_quote.gif 
_If the resistors around it are well matched, it should be close to 0mV._

 

I don't think the resistors around it are well matched: R8 and R9 are 36K whilst R14 and R17 are 22K. In fact in the original modder's photo that Adamus posted, it looks like he has replaced R14 and R17 with 36K ones.


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## adamus

agreed, probably why its so cheap. so it will present some offset. not sure why the designer did this, but with caps in there it wont matter.


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## guzzler

Quote:


  Originally Posted by *keiths* /img/forum/go_quote.gif 
_I don't think the resistors around it are well matched: R8 and R9 are 36K whilst R14 and R17 are 22K. In fact in the original modder's photo that Adamus posted, it looks like he has replaced R14 and R17 with 36K ones._

 

You're looking at the wrong thing. It's in a differential configuration, so it's the matching of the resistor network on each opamp input, ie, R10 = R11, R15 = R16 (can't quite see the schematic clearly), with R8 (=36K?) setting the gain, hence not equal to R14. Given that resistors are 1% tolerance generally, if you were doing it yourself you'd match the resistors by hand but at this price that's obviously not practical.


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## keiths

^^^ Thanks, guzzler. So I wonder why the original modder changed R14 & R17?


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## fordgtlover

This thread has a lot of information.


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## 00940

Quote:


  Originally Posted by *keiths* /img/forum/go_quote.gif 
_^^^ Thanks, guzzler. So I wonder why the original modder changed R14 & R17?_

 

Because he bypassed the caps in between the dac and the opamp, as explained in the thread on the artofsound forum.

 If there is no DC offset, you can alter the gain of the balanced receiver, as explained by Guzzler, by simply altering one resistor. However, if there is some offset and the gain is set only by one resistor, the offset won't cancel anymore (in this case, you will get 800mv of offset if ltspice doesn't lie).

 However, you can perfectly well get gain and remove any dc offset by using identical values R8-R14 and R15-R16. It will depend on the ration R8-R15. Just have a look at the datasheet of the pcm1794 for example, p 20 and 21.


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## keiths

Thanks everyone. Seeing the thread on The Art of Sound certainly clears things up - especially this post which covers just about everything discussed here so far.

 I've already bypassed C27, C28, C30, C31, C6 & C54. I don't really feel like tackling the resistor and capacitor changes required to remove the DC offset, so I'll just add output caps and leave it at that for now.


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## keiths

Finally got round to finishing it. I put the transformer in a separate box.







 On my desk beneath my desktop Starving Student






 Sounds pretty good. I swapped the op-amp for a LM4562NA and it sounds nice and detailed.


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## adamus

sound much better than my aliendac (unfair to compare though, alien is portable, self powered etc - the two obbligato caps i used are bigger than the alien). 

 I use an opa2107 and obbligatos, very refined.


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## gurusan

looks very nice. What is that pot? Does that control the analogue out volume?

 I will be building a starving student and have also just purchased one of these DACs. I also have some spare LME49860 opamps laying around that will hopefully sound nice.

 Just got my HD 580 cans as well and they even sound quite nice directly through onboard sound....I'm stoked!


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## keiths

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_What is that pot? Does that control the analogue out volume?_

 

It's not a pot - it's a rotary on/off switch.


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## gurusan

ah ok that makes sense


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## adamus

noodle dac, with obbligato output caps


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## fordgtlover

That looks like a bijou PS board next to the case.


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## adamus

yes it is. start building. IT may take a while though, i still havent ordered my transoformer. its going in another hifi2000 case (very cheap for us europeans!)


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## fordgtlover

The Bijou is a very nice amp. I really enjoy mine. The combo of this ebay dac and the bijou sounds very nice.


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## gurusan

i have this DAC and am waiting on an enclosure, toslink cable, and a few other tidbits to get it connected up. I have a spare LM4562 that I will be replacing the opamp with and will be removing all the aforementioned caps.

 However, I don't know which coupling caps to go for. I looked at the obbligatos but they are quite expensive. Can anyone make some more affordable recommendations?


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## adamus

wimas are fine. more punchy then the obbligatos (which are more of a smoking jacket and cigar type of sound). 

 I have a few if interested. 

 You could try clairtycaps (british make). have a look round hifi collective. You dont need anything bigger than 2uf as you will almost certinaly be showing this a high impedance output (eg a 50k volume pot).


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## gurusan

I already have a few of these from a cmoy build, would they be sufficient?

http://uk.rs-online.com/web/search/s...uct&R=544-1298

 Would these by any better suited?
rswww.com |* MKS4/1.0/63/10, Wima, MKS4 Polyester Cap,63Vdc,1uF, 108-2801


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## adamus

you need over 1uf, those your have are 0.1 and you will likely see some bass roll off. 

 The mks4's are ok, but the mkps are better imo.


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## gurusan

ok thanks that clears some stuff up.


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## keiths

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_you need over 1uf_

 

I used 0.47uF Mundorf MCaps and don't notice any bass roll-off with my Starving Student.

 Is 0.47uF too low for a 50k pot? As f = 1 / 2 x Pi x C x R that gives 6.77Hz (I think) I haven't listened extensively through my speaker amp which has an input impedance of 22k (so f would be 15.4Hz) but again didn't really notice any lack of low bass.


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## adamus

that should be fine. 

 I only say fo for 1uf, some amps etc have 10k input impedance.


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## holland

Is this board still available somewhere? I couldn't find it on an e-bay search.


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## adamus

HI END 24bit/192Hz HI-FI DAC DIY KIT , ASSEMBLED MODULE on eBay, also, CD Players, Home Audio Hi Fi, Consumer Electronics (end time 12-Sep-08 12:36:33 BST)


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## keiths

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Is this board still available somewhere? I couldn't find it on an e-bay search._

 

[Adamus beat me to it]


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## gurusan

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_that should be fine. 

 I only say fo for 1uf, some amps etc have 10k input impedance._

 

I have a 10k pot on my cmoy...this explains the lack of deep bass I have been noticing. I thought it was just the sound signature of the amp but now I know better because I know that equation!

 I had .1uF input caps which gave me a 159Hz bass rolloff! :/

 I now have a mix of different caps on their way to me. Some Philips 2.2uF, 3.3uF and Wima MKP10 .33uF 

 According to you and some research I've done the Wimas are very good, but I can't find much info on the Philips. I hope they will be ok as the Wimas are only .33uF which will make F about 48Hz....not bad but obviously still within the audible spectrum! :/



 However I am confused on 1 thing. Do you really need output caps on the DAC if there are already input caps on the headphone amp? Sorry for all these noobish questions but I have to learn some how! 
	

	
	
		
		

		
			





 Also 1 addition question, if I have the space can I wire up two .33uF Wima caps in parallel for each channel to get a net of .66uF? I mean I know you can do it but are there other factors such as distortion that will also double by putting in another cap alongside the original?


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## adamus

just parallel 2


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## guzzler

It's worth putting the caps on the DAC if you intend to use it for anything else. If you're certain it will only be with an amplifier with AC coupling, then fine, but it's a bit of a risk...

 Also - regards the rolloff frequency, what you've quoted is the -3dB point but there will be attenuation and phase shift at much higher frequencies. As you're still dealing with relatively small capacitances, try and get your -3dB point below 10Hz.


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## gurusan

ok thanks. I'll just try out different combos and see what sounds best.


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## adamus

Amen to that. 

 Last night i changed the interstage caps on my soa + jisbos. The caps had the 3db point at 27 hz and everything sounded a bit hollow. 

 Put some 1 uf obbligatos in and what a difference. deep bass, much stronger mid bass. Its a different amp. the obbligatos need some time though, they sound ever so slightly 'plastic' a bit too smooth. almost like i need slightly more extension up top.


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## gurusan

got my Chinese DAC up and running and installed in a case under my CMOY just for testing. 






 Currently have it from my P5Q ADI200B optical out and it sounds pretty good. 
 Next I'm going to swap in a LME49860NA opamp I have here, going to add a power LED, remove some caps and bypass the output stage to go straight to my CMOY.

 I crammed the transformer in there (superglued it to the roof as far away from the DAC board as possible) along with the other audio components and can't detect any humming or EFI symptoms...but I will buy some copper tape and make some kind of shield just for peace of mind.

 and 1 question, does this need any ventilation as the Vregs got warm after just a few min. I'm thinking of just drilling a ventilation hole up top and on the bottom to let out warm air?


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## keiths

^^^ Looking good, Gurusan.

 FWIW, I drilled a quite a few vent holes in my DAC's case (top and back, close to the VRegs). As you say, the regs' heatsinks get pretty toasty.

 I got some larger value MCaps (1.5uF) and am going to install those tonight to get the -3dB point below 10Hz when the DAC is used with my Arcam speaker amp.


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## gurusan

yeah i think it definitely needs some ventilation.

 After about 10 min the large heatsink was 58C...and a few minutes later evened out to about 60C...and this is outside the case!

 .....does anyone know the temp specs for these VRMs? 






 On another note, this DAC sounds seriously good! Going from Winamp playing FLAC rips -> ASIO -> Optical out -> DAC -> CMOY -> HD-580 

 I have swapped a LME49860 in (LM4562) and it sounds MUCH better...but I would like to bypass the outstage completely and for the signal to go straight to my CMOY.

 How can I do this?


 and another sidenote, I changed out the .1uF output caps on my CMOY to 2.2uF caps and OMG I didn't realize how much my bass was lacking before. Now my -3dB point is at 7.23Hz instead of 159! lol!


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## adamus

the 7812's etc go up to 105, some 150.
 60 is fine.


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## error401

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_the 7812's etc go up to 105, some 150.
 60 is fine._

 

The temperature in the datasheet is the maximum junction temperature, not the case or ambient temperature. The junction will be much, much hotter than the outside of the case, and you need to do some math to figure out exactly how much hotter.

 Read ESP - Heatsink design and transistor mounting if you're interested.

 Though I agree that 60 is probably 'fine', but it's still quite hot.


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## regal

This DAC + a Pass BOSOZ = a low cost Ori Zahlou. Probably better.


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## gurusan

I bypassed the entire output stage on the DAC so the analogue signal is going straight to my cmoy and it sounds very, very good!

 I used to have a X-FI with a bunch of mods which sounded pretty decent but this certainly beats it!


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## gurusan

Got everything stuffed into the case with some ventilation. Casework is much harder than I thought! Couldn't get things to line up properly and I got fed up after awhile... now its good enough for me, even though the rear of the case is a bit rough, lol. I might have another go with a new case in the future.


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## adamus

tip for case work: digital calipers and a diagram stuck to the case,


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## gurusan

yeah i had it covered in masking tape and drew all over it but digital calipers most certainly would have helped!


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## fordgtlover

Everyone with this DAC should check out this post over at theartofsound.

 I did the mod that the poster mentions, but also did a whole bunch of other changes so I can't confirm the results. 

 My version of this little DAC is sounding very nice; very revealing.


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## gurusan

So....without any warning my DAC started buzzing a whole ton through the outputs...the little crappy transformer that came with the DAC got VERY hot and started to melt my case.

 Any idea what could have caused this? it was working fine for over a month. Just a cheapo transformer? What kind would you recommend for a cheap but good replacement? 

 I wonder if the DAC itself is still good...


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## AZNracerx1989

I am about to get this DAC too! But I plan to do those mods PLUS these ones CD DAC Lampucera lampizator

 Anyone know if they have any conflicts with one another?


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## gurusan

So I'm looking for a suitable replacement transformer for the DAC. Can anyone recommend one that is not very expensive, but won't fail like the last one did?

 I need one that will output 12V on the secondaries, correct? What sort of VA rating should I look for? I understand the DAC does not take much current but will there be any better regulation with a higher VA rating?


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## mwofsi

Quote:


 better regulation with a higher VA rating 
 

I think that for transformers regulation refers to the difference between loaded and unloaded voltages. For an ic regulated supply this shouldn't be a problem as long as the rectified unloaded voltage (x1.42?) doesn't exceed the component ratings for things such as caps in the power supply (I believe Tangent suggests [rectified unloaded voltage x 2] as a safer way to determine cap voltage ratings). I'll offer more comments and suggestions if those more knowledgeable don't chime in.


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## gurusan

So would something like this be adequate?

Transformer Toroid 0-240 / 2x 0-12 11VA, 8-0-8 3VA on eBay, also Transformers, Components Supplies, Electrical Test Equipment, Business, Office Industrial (end time 02-Nov-08 16:17:55 GMT)


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## AZNracerx1989

What kind of input ac voltage does the power supply need? I am wondering this too


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## mwofsi

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_So would something like this be adequate?

Transformer Toroid 0-240 / 2x 0-12 11VA, 8-0-8 3VA on eBay, also Transformers, Components Supplies, Electrical Test Equipment, Business, Office Industrial (end time 02-Nov-08 16:17:55 GMT)_

 

 Power to spare I should think. Isn't it a little large?

 Looking at the ebay photos on gigaworks, they show dual 9V secondaries, with a 0.39A (390mA) capability for each. I make that 14VA which should also be more than adequate. 

 If your not going to use the dacs opamp output stage you wont need the +/-12V part of the supply and may be able to get away with a smaller voltage, even if the power supply is wired so that everything goes through the 12V regs. Say add 3V for the 7805 dropout voltage that's 8v rectified, one 6V secondary of perhaps 100-150mA would do. That would greatly reduce the heat output. EDIT; not 100% sure on that 'cause I 'm not sure how a regulator would behave with such a low voltage going through it.
 EDIT: I'm also making the huge assumption that the opamp is supposed to use a bipolar supply (+/-12V), as I only have a partial circuit diagram.


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## gurusan

Well the output stage is already completely bypassed. My RCA outputs are tapped directly into the +R and +L from the receiver.

 This is the transformer that came with it (the one that got super hot and melted my case)


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## mwofsi

In that case you obviously have no need for a +/-12V supply, just the regulated 5V, which gets fed to the dac board and is there also regulated to 3.3V.

 Bit concerned about the melting transformer. A small enough fuse might have stopped it. Possible cause: a faulty transformer, a wiring short, or the heat in your case being to much for it and causing a fault.

 I believe the VA rating of your transformer is (12+12)x(0.292+0.292)=14VA. Should have been adequate if all was well.

 btw seeing as I just burned a TLE in the same way, both this and your cmoy supply secondaries are isolated from mains earth aren't they?

 Another thought, is your cmoy power supply capable of providing a power feed to your dac? Separate supplies are often preferred but it may work well


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## gurusan

If 5V is all I need to power the DAC, then can I just steal it from a USB port?


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## mwofsi

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_So basically i just need a transformer with only 5V secondaries?_

 

Not quite, 5V ac rectified produces 7.1V dc. The ic regulator, the 7805 needs a dc feed of a max of 2.5V above it's output voltage to ensure that it works/regulates. So 6V secondaries, I believe.

  Quote:


 And my CMOY power supply is a DC wallwart 12V. 
 

Depending on it's VA rating you could possibly use this to power both items.I think it gets a little complicated depending on how the dac power supply board is wired. I can't figure it out, you need someone who knows more.
 Mind you some people prefer the sound of a cmoy run at higher voltages, say 24V! (me for instance)

  Quote:


 I would like to learn a bit about PSUs though, so if all I have to do is give the DAC a 5V source then how difficult would it be to build a PSU? 
 

Read up on Tangents Tread power supply, what little I know I learned there. Also see regulator datasheets. For you, pretty simple, Maplin will have the parts if you don't mind higher prices and lesser quality capacitors.

  Quote:


 I just need to step down 220 to 5V, then rectify it into +5V and -5V, then feed to the DAC, correct? 
 

No, see above! The dac only needs a single supply of +5V, no negative required.

  Quote:


 Or am I just better off buying a 5V dc wallwart 
 

Again Tangent knows one hell of a lot on this subject. It's a possibility but it's likely to be a downward step. Power supply improvements are often a way of improving dac performance.


----------



## gurusan

great. you've been a great help. Thanks for all the info


----------



## mwofsi

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_If 5V is all I need to power the DAC, then can I just steal it from a USB port?_

 

Complicated, it's a poor quality power supply. Best avoided, though Alien dacs and the like do this.

 EDIT: Your welcome.


----------



## ls206

is this DAC imported? the only kits I could find are from HK


----------



## mwofsi

Quote:


  Originally Posted by *ls206* /img/forum/go_quote.gif 
_is this DAC imported? the only kits I could find are from HK_

 

Yes, that's correct


----------



## ls206

hehe, thanks. It's a shame there's literally no diy audio on ebay UK


----------



## mwofsi

Quote:


  Originally Posted by *ls206* /img/forum/go_quote.gif 
_It's a shame there's literally no diy audio on ebay UK_

 

One gets used to it. Don't think I've had anything of this size/cost fom HK, but I've gotten smaller items. Taiwan as well, also similar and larger items from America.

 It's all usually quite painless. Usual precautions about checking ebay feedback or you could ask in the forum about specific sellers. You may get charged taxes/import duties on anything over £18.

 EDIT: Returning faulty items could be a pain though.


----------



## gurusan

So i decided to go ahead and use the PSU that came with the DAC again...

 The caps seem to be of decent quality but the +5V voltage regulator (all I need since I bypassed output stage) seems questionable. It's an L7805CV 

 THe product sheet says:
 Load Regulation100mV
 Line Regulation50mV

 I was looking at the LM1086CT-5.0...and it says:

 Load Regulation20mV
 Line Regulation10mV

 That has far less ripple so I would assume it would make for a reasonable upgrade since it only costs 80p?


----------



## mwofsi

Quote:


 I was looking at the LM1086CT-5.0...and it says: 
 

Well we're well out of my league here, but looking at the data sheet they're not
 pin compatible. That is the input/output pins aren't in the same place.

 Also, I think you'll find that the Ripple Rejection/Supply Voltage Rejection are more important, than it's absolute ability to regulate. The caps also play a role in maintaining steady voltage I believe and the absolute value is rarely important in audio.

 You could salvage parts and air wire or use perfboard. Also are you sure that the
 L7805 is dead?

 The adjustable LM317 has the best Ripple Rejection I've seen but needs a few resistors, cap and diodes as in the tread. Similar kits/units are available from Tangent and ebay.

 EDIT: Tangent agrees with you and writes that the LM1086 can offer an advantage but scroll down to "Choosing a Regulator" here: http://www.tangentsoft.net/elec/tread/pguide.html


----------



## AZNracerx1989

I got a OPA sun HDAM i am going to put in this thing xD


----------



## adamus

gurusan, is this back up and working? i would stick with the 7805, they are fine for the job.


----------



## gurusan

not yet. I'm waiting on my toroidal transformer...and thanks guys I will stick with the 7805.

 But for future reference, is it better to have a lower ripple and supply rejection or higher?


----------



## mwofsi

gurusan, if you haven't already check your power supply by ensuring there's no short between the 12-0-12 inputs. If thats ok set up a resistor divider and connect a 9V batterry (less risk than using your 12V wallwart) to the supply. As long as the ground/0 position corresponds it won't matter which of the 12V inputs is +ve or -ve. Check for 5V at the output.

 Sorry it took me so long to figure that out 
	

	
	
		
		

		
		
	


	




 (EDIT: whether you actually get the complete 5V out may depend on the rectifier set-up of the power supply)

  Quote:


 I got a OPA sun HDAM i am going to put in this thing xD 
 

Should be interesting, only the Zero crowd seem to have been making much use of them.

 EDIT: Quote:


 But for future reference, is it better to have a lower ripple and supply rejection or higher? 
 

Higher, as in more decibels. Always get confused about decibels, but dB is a ratio and 3dB increase is double what went before.


----------



## error401

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_But for future reference, is it better to have a lower ripple and supply rejection or higher?_

 

The measurements given are how much the noise is attenuated by the regulator. More negative numbers (in dB) are better. 0dB means the noise goes through untouched. Greater than 0dB means it is amplified (??!?).


----------



## mwofsi

Quote:


 Greater than 0dB means it is amplified 
 

Oops, thankyou error401.

 EDIT:If I knew what I was talking about I should have said 3dB decrease is double the ripple rejection that went before. Editted Edit: And ripple rejection can also be expressed in other figures, more being the aim.


----------



## gurusan

Quote:


  Originally Posted by *mwofsi* /img/forum/go_quote.gif 
_gurusan, if you haven't already check your power supply by ensuring there's no short between the 12-0-12 inputs. If thats ok set up a resistor divider and connect a 9V batterry (less risk than using your 12V wallwart) to the supply. As long as the ground/0 position corresponds it won't matter which of the 12V inputs is +ve or -ve. Check for 5V at the output._

 

Thanks, will do that next.

 hmm, should have brought it with me to my electronics lab today...would have been interesting to put some load on it and see what shows on the oscilloscope.

 Oh well. 
	

	
	
		
		

		
			






 Oh, and one other question. In a simple Vreg circuit as used on this noodle DAC psu, what is the function of the polysester caps on either side of the regulator? I have some really questionable looking .0033uF caps on there at the moment but have some .0047uF Wima MKS02 caps I was thinking of putting on there just for piece of mind? Also have LOTS of .33uF Wima MKP10 ?


----------



## mwofsi

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_Oh, and one other question. In a simple Vreg circuit as used on this noodle DAC psu, what is the function of the polysester caps on either side of the regulator? I have some really questionable looking .0033uF caps on there at the moment but have some .0047uF Wima MKS02 caps I was thinking of putting on there just for piece of mind? Also have LOTS of .33uF Wima MKP10 ?_

 

Could also be wrong here, and having used them myself...

 If they're in parrallel with the input and output electrolytics, I believe it's a case of questionable implementation, ie they're not needed and may cause resonance.
 It's possible they're there as bypass caps to improve the sound signature of the power supplies noise output, or to improve it's frequency response. Apparently more modern manufacturing techniques mean that modern electrolytics are already capable of these tasks.

 [Steps back and waits for flak]


----------



## linuxworks

I just found this thread. here's some pics I took of my work-in-progress 'noodle dac' (love that term; up to now I was calling it a chinse DITB (dac in the box).

 it arrives:






 (does it come with shrimp??) 
	

	
	
		
		

		
		
	


	









 nope, just a photo of shrimp. darn. probably wouldn't have lasted the trip anyway.











 and my first test, using a 'true breadboard' (lol)






 I then added a digital volume circuit (ds1802) to it:











 a few days ago, I did the 'lampizilla' (or whatever it is!) set of mods to replace quite a few of the bypass caps and 'lytes. changed out the op-amp to a BB or AD chip and that's about all so far.

 its a pretty good DIY mod platform.


----------



## gurusan

Quick question...what is this thing?


----------



## DaMnEd

Looks like a ferrite bead.


----------



## linuxworks

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_Quick question...what is this thing?




_

 

ferrite bead over tinned 'cutoff lead', I think.

 it bridges the + side of the diode bridge (its + output) with the +5v regulator (7805) input line, pin1, on the to220 chip.

 I'm pretty sure its a FB. no markings on it and while it has a shiny plastic look to it, it seems to have the wire go thru it so its bead-like in appearance 
	

	
	
		
		

		
		
	


	




 its the supplied PS - I didn't make it


----------



## mwofsi

gurusan, the ferrite bead you highlighted has lead me to some further thoughts about this supply

 I think the bead is possibly there as an attempt to reduce switching noise from the bridge rectifier diodes.

 Also if there is only one, that suggests that the rectification for the 5V supply
 is being done utilising only two diodes (from the bridge) and the centre tap of
 the transformer. So if you have a three output wired 12-0-12 transformer you
 would need to connect all three wires but only 12V ( not 24V) of that will be
 rectified then sent to the 5V regulator. Dropping a rectified 12Vac down to 5V 
 could be the cause of considerable heat.


----------



## nsx_23

Can I ask a stupid question: Where can I buy one, and get it cased?


----------



## fordgtlover

You can buy them on ebay
24bit/192KHz DAC DIY KIT , FULL ASSEMBLED KIT - eBay, Processors, Home Audio, Electronics. (end time 06-Nov-08 04:24:34 AEDST)

 Casing one of these is quite straightforward, but finding a nice case in Australia can be a challenge.

 I used a cheap Jaycar case. It is effective but pretty ugly.


----------



## mwofsi

Maybe this is slightly cheaper?

High Grade 24bit/192khz DAC with fully assembled kits on eBay, also, CD Players, Home Audio Hi Fi, Consumer Electronics (end time 31-Oct-08 08:00:00 GMT)

 Prices seem to be going up, the same ebay store seems to have another at a higher price.


----------



## fordgtlover

^

 Yep. It's definitively cheaper (by about AU$35).


----------



## linuxworks

Quote:


  Originally Posted by *fordgtlover* /img/forum/go_quote.gif 
_You can buy them on ebay
24bit/192KHz DAC DIY KIT , FULL ASSEMBLED KIT - eBay, Processors, Home Audio, Electronics. (end time 06-Nov-08 04:24:34 AEDST)_

 

I would take a miss on the transformer, though. they tend to be hummy right at the start ;( physical hum from windings. plus I'm not sure they are made well and probably are borderline unsafe (imho).

 the tronics are fine but the shipping for a bulky junky transformer that you need to replace immediately makes less than no sense 
	

	
	
		
		

		
		
	


	




 now, if they starts subbing a torroid, NOW we can talk about shipping a transformer 
	

	
	
		
		

		
		
	


	




 but that ugly bad thing is not worth shipping or using.


----------



## gurusan

Since I bypassed the output stage on the DAC, I only need 5V. I want make a smaller PSU using some parts from the one that shipped with it and some of my own. (Sanyo WG 1500uF after vreg)

 I am completely noob but just threw this together pretty much 99% based off the DAC schematic.

 Anything wrong with it? The 12V is coming from the diode bridge from the DAC psu, AC coming from a small 1.6VA toroidal 12+0+12 I purchased the other day


----------



## mwofsi

Hopefully error401 or someone will chime in on this, but that looks like a huge amount of capacitance for a 5V supply. I don't know the technical reasons, other than vague memories of bits I've read, but it's not usually the way it's done. One 4700uF and one 1500uF should be more than enough.

 Of course that rectified 12Vac from the diode bridge is more like 17Vdc, which is rather a lot to drop to 5V in terms of heat generated. I don't know whether it would be a benefit or if that's what you meant, but using the parts you had you could first regulate to 12Vdc and then regulate that to 5V. It might improve ripple levels slightly but may not improve supply noise. The ripple at least you could check on your scope, the noise levels may need an amplifier to examine such as Tangent's LNMP.

 Also paralleling different sized caps will probably lead to resonances/increased noise, perhaps even instability. If you are going to do that may I suggest leaving out the .0047uF before the regulator, and experimenting with using the one after as shown to see whether you can hear any difference with it there or not. 
	

	
	
		
		

		
		
	


	




 Other than that it would probably actually work fine as it is.


----------



## gurusan

Well I have a 12V regulator here so I might as well use it. 

 I'm unsure of which cap to use between the to regs though...

 rectified DC --> 4700uF ---> 12vreg ---> 4700uf ---> 5vreg ---> 1500uf ---> 5v out to dac

 Anything I'm doing wrong here?


----------



## mwofsi

Again, I may be way off base here but I would be inclined to use smaller caps between the regs and after, say 100uF. It's my belief that the size of the caps influences the power supplies ability to respond to changes in demand.

 I know for sure that it is a complicated subject, power supplies, their recipient and even the distance between the two are all intimately related. It's possible that I'm wrong about my conclusions here.

 I hope that I'm being of help.


----------



## 00940

I wouldn't bother with a second reg. You're dropping a lot of voltage but not a lot of current. If anything you could try a crc filter. Something like that: 4700uF- 33r/1w-4700uF-lm7805-470uF. If the regulator is kept close to the caps, there is no real need for film caps there; those belong to the local decoupling.


----------



## gurusan

I tried googling CRC filter but could not find any information I understood. Can you please clarify what exactly that is and what it will do for the circuit? 

 thanks guys


----------



## 00940

The crc just consists into dropping a big resistor in serie before the reg. Let's say you have a current draw of 100ma. If you put 33r in serie, V=R*I, so you drop 3.3V. If you put 50R, you'll drop 5V.

 Now, that reduces the power dissipated by the reg from 12V*0.1A= 1.2W to 7V*0.1A= 0.7W. For a 50R resistor, the power dissipated by the resistor itself will be : 50*0.1*0.1=0.5W. Thus you have to pick at least a 1W resistor.

 The name crc means: cap-resistor-cap.


----------



## gurusan

thanks for all that.

 Ok so I actually found a regulated DC wallwart in my closet that puts out about 12.8V DC, I think this will make my PSU smaller and more simple.

 Redesigned my little PSU circuit for the DAC as follows...


----------



## linuxworks

should your 7805 be driving such a heavy cap load?

 usually its high cap in front of the reg and a small one after.


----------



## gurusan

The cap on the PSU that came with the DAC is 1000uF... but some cheapo cap. I wanted to put some Sanyo WG caps I have there but I only have 1500uF


----------



## linuxworks

you're right! I just checked and was surprised to see such a high value there. I had not noticed it before 
	

	
	
		
		

		
		
	


	




 I wonder if it was really needed. seems rather brute force to put THAT much -after- the reg.


----------



## gurusan

Well are there any downsides to it? I am ordering a few things from rs-online so if there's a more ideal size I might as well get a few.

 470uF? or just a better 1000uF?


----------



## linuxworks

I have that PS (of course) and it DOES seem to work pretty well.

 it just surprised me to see that brute force amount at the end.

 just make sure you get 105C (temp) caps and a good safety rating of volts over what you are putting out.

 personally, just my guess - the 470 is probably more than you'd need anyway. otoh, the chinese manuf. usually do NOT put stuff on boards that isn't needed. they are often NOT putting things on boards, so any board part probably has a really good reason for being there else it would have been cost-reduced OFF the board


----------



## gurusan

So I got my little PSU setup and the DAC works again! Now running it via optical from PC to DAC to my Starving student and it sounds VERY good through my HD 580s!

 I am using a 12V DC linear regulated wallwart I had hanging around...So my little PSU has ~12V in, drops a few volts across a 1W 33R resistor...gets filtered a bit through a 4700uF Rubycon YK cap from the old PSU...then gets regulated to 5V with the l7805 from the old psu...then gets some final treatment with a 1500uF Sanyo WG I had from my old XFI project.

 Here are some pics of it, to compare size with the old psu as well.


----------



## gurusan

Ok with no load (psu circuit only, DAC not hooked up), my output is 5.00V according to my DMM....but with the DAC on and converting an SPDIF optical signal it uses between 131-132mA....and my voltage is jumping between 5.05V-5.08V.

 How can I fix this? The resistor is dropping about 4.36V from the 12.7V source so the L7805 is only dropping about 3.34V... are the film caps in the original dac PSU needed to keep the vReg stable?

 Also the 1W 33R resistor is quite hot...but according to my calcs it should only be putting out about .57W of heat? Is it normal for these to retain heat as there's not much surface area to dissipate it.


----------



## adamus

half a watt, over small package like a resistor will put out some heat. as long as its within spec it should be fine.


----------



## gurusan

Ok thanks...any thoughts on the .05-.07V overvolting on the 5V output?


----------



## Nemo de Monet

Quote:


  Originally Posted by *gurusan* /img/forum/go_quote.gif 
_Ok thanks...any thoughts on the .05-.07V overvolting on the 5V output?_

 

I wouldn't worry about it; that's, what, a 1-1.4% variance? That's pretty good, given the basic design you're using. If you check the L7805 datasheet, you'll see it's "within spec" between 4.8 and 5.2 VDC. The L7800 family of regulators have a lot of nice features (thermal and short-circuit protection, for example) but "high precision" isn't one of them.


----------



## gurusan

ok...well if not just to learn something, how would I go about getting the 5V out more stable?


----------



## Nemo de Monet

It's really fairly pointless, but you could use something like Texas Instruments' TL780-05, a 1% "precision" regulator. It's debatable whether it would actually provide "better" regulation in your application, and even more debatable whether it'd have any meaningful (audible/measurable) effect on your DAC's output.

 I mean, to put things in perspective, most reasonably common, reasonably affordable multimeters are probably accurate to 1% or less, so you're worrying about variances that are probably not reliably measurable. Considering what passes in the world for "12VDC", a few hundred millivolts from nominal on your DAC power supply is *more* than "good enough"...


----------



## gurusan

ok, gotcha.

 But anyway.... I happened to have a few spare National Semiconductor LM1086-5 regulators around from a project a long time ago. 

 I popped one in to replace the old L7805 and now the DMM reads 5.01V constant. You are right, I can't detect any audible difference, but my obsessive mind is at ease now


----------



## AZNracerx1989

I used the opa sun hdam on this DAC and it sounds really good! But where do I ground it? AG or the other grounds?


----------



## kirimaru

I just recieved the dac,its sounds ok but it make hissy noisy when the sample rate is over 48khz.
 I think i am missing something,can somebody enlightme ?
 thanks.


----------



## linuxworks

I believe you have to change a few things (nothing big, though) to get 96k to work!

 research it but it does not support 96k as shipped. look for that lampazilla (sp?) guy - his website had some dialog on what things to wire where to get 96k 'back' again.


----------



## adamus

edit - beaten to it

 yes, you need to do a mod to get it working over 48khz. look on the diyaudio forum. Its somewhere in there (digital section)


----------



## gurusan

done this and confirmed as working. careful lifting the leg though. might be best to just cut the trace

diyAudio Forums - CS8416/CS4397 board at 96kHZ? - Page 1
  Quote:


  Originally Posted by *error401* 
_I would normally expect a DAC using this IC/receiver combo to utilize the 96KHz pin on the CS8416 to select a high sample rate mode in the DAC when you apply such a signal. An obvious failing of the design. M4 is the CS4397 pin that puts it in high sample rate mode, you'll need to disconnect it from ground and apply an appropriate signal.

*You will need to carefully lift the M4 pin (2) from the PCB (...), and bridge it to the CS8416 96KHz pin (16) with a wire. This pin is an output so shouldn't be connected to anything and you won't need to lift it.*_


----------



## kirimaru

Thanks to all of you guys,you all were very helpful.
 the dac is working perfectly at 96khz.
 thanks.


----------



## linuxworks

hey, leave us with a photo or something!









 glad it worked out.


----------



## kirimaru

I am going to recap the dac, so i will post the pics tomorrow.


----------



## fordgtlover

Here's my recapped version





 I've made the following changes:
 R2 3K
 C3 10uF 10V oscon
 C8 .1uf Polypro 
 C9 .1uf Polypro
 C10 .1uf Polypro
 C11 .22uf MKT EPCOS
 C12 .1uf Polypro
 C13 .22uf MKT EPCOS
 C16 100uF 16V os-con
 C17 100uF 16V os-con
 C18 100uF 16V os-con
 C19 Rubycon MBZ 1500uF
 C20 100uF 16V os-con
 C21 470uF Panasonic FM
 C22 22nF
 C23 1nF
 C25 10uF 10V oscon

 R8, R9, R14, R17 30K
 C32, C33, C34, C35 150pF

 Opamp opa2107

 Leo's bypass mod
 C27,C28,C30,C31,C6,C54 Bypassed
 L & R out C 2uF Obbligato PIO
 L & R out R 51 Ohm Kiwame


----------



## adamus

I use the 2107, tried quite a few and it was the king.


----------



## kirimaru

Sorry for the delay,here is the photo.





[/url] 

[/IMG]


----------



## fordgtlover

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I use the 2107, tried quite a few and it was the king._

 

I have got to admit that the 2107 was the first one I grabbed. I liked it so I haven't rolled any others 
	

	
	
		
		

		
		
	


	




, but I have made up for it by swapping out a stack of caps.


----------



## dean0

Putting together this dac from ebay, done all mods etc. but did not get a transformer with it. What size/rating do I need (uk voltage)? Any links would be helpful, thanks in advance


----------



## linuxworks

which mods did you do?

 I lost track and never really settled on any magic setup, myself. I have a half-disassembled board but there was so much to read thru to find the 'final' config that everyone liked - I kinda gave up and moved on 
	

	
	
		
		

		
			





 if you are using the onboard opamp, you need 5, 12, -12v. if you don't use the opamp and are powering only the dac, you only need 5v.

 I was planning on bypassing the opamp (just tapping into the dac's - and - outputs for the l,r) and supplying the rest, myself. in that case I'd only need 5v for that.


----------



## gurusan

i am using only 5V to power the DAC as I skipped out the opamp stage and it sounds great.

 I'm actually just using an unregulated 300ma 5V phone charger which then gets cleaned up by a CRC filter, a few caps, and a 5V regulator.


----------



## dean0

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_which mods did you do?

 I lost track and never really settled on any magic setup, myself. I have a half-disassembled board but there was so much to read thru to find the 'final' config that everyone liked - I kinda gave up and moved on 
	

	
	
		
		

		
		
	


	




 if you are using the onboard opamp, you need 5, 12, -12v. if you don't use the opamp and are powering only the dac, you only need 5v.

 I was planning on bypassing the opamp (just tapping into the dac's - and - outputs for the l,r) and supplying the rest, myself. in that case I'd only need 5v for that._

 

thanks bud, only done bypass mod so far but I have few more planned 
	

	
	
		
		

		
		
	


	



 Is this the transformer i will need? Nuvotem | Transformers | Transformers | Toroid Transformers | Toroidal Mini Open Style 115-230Vac Primary 1.6VA to 7VA


----------



## dean0

anyone? I cannot find this infomation anywhere


----------



## dean0

[/url]

 Test fit, dac/psu still need recapping, just need to know what transformer I need............................


----------



## Pars

Did you perhaps try doing a search of this thread for starters?
http://www.head-fi.org/forums/search.php?searchid=8188344

 Also, on the previous page of this thread, in post 143 is a link to diyaudio which also might be a great place to get the info you seek. As well as asking the seller that you bought this from.

 I don't own one of these BTW.


----------



## dean0

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Did you perhaps try doing a search of this thread for starters?
http://www.head-fi.org/forums/search.php?searchid=8188344

 Also, on the previous page of this thread, in post 143 is a link to diyaudio which also might be a great place to get the info you seek. As well as asking the seller that you bought this from.

 I don't own one of these BTW._

 

thanks bud


----------



## V-DiV

Quote:


  Originally Posted by *linuxworks* /img/forum/go_quote.gif 
_if you are using the onboard opamp, you need 5, 12, -12v. if you don't use the opamp and are powering only the dac, you only need 5v._

 

I just received my 'noodle' DAC. I got it without the transformer. Does anyone have a Mouser part number for a good one to power this? I have read the entire thread more than once and I don't believe one was listed. I'm going to run with the opamp (Adamus' pick), at least to start. Thanks.


----------



## adamus

I havent measured mine, but i guess a 12v toroid is what you want. doubt you would need anymore than 20va either. you using the powersupply board?


----------



## V-DiV

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_you using the powersupply board?_

 

Yes, I just want to get it up and running first. Then I'll start playing with modifications.


----------



## adamus

I think 12v dual secs is what you want.


----------



## L_u_k_a_s

I'v been advised by seller of such a DAC to use 12-0-12VAC 500mA power supply. You can get centre tapped toroid, but easier and cheaper is to use regular toroid with two secs, 15 VA, and tie two wires from secs together - this connects to "0" on DAC separate AC->DC board.

Nuvotem | Transformers | Transformers | Toroid Transformers | Toroidal 230Vac Primary 15VA to 1000VA


----------



## ericj

Just got one of these, and i have to say, boy, the quality. Where is it?!

 Pin 2 is lifted and bent over to pin 3 on the dac. Easy to fix, but, gives one the impression that these weren't inspected at all. 

 I don't get what people are doing to remove the opamp stage entirely - i mean, given that the output of the DAC is differential (aka balanced).


----------



## fordgtlover

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_Just got one of these, and i have to say, boy, the quality. Where is it?!

 Pin 2 is lifted and bent over to pin 3 on the dac. Easy to fix, but, gives one the impression that these weren't inspected at all. 

 I don't get what people are doing to remove the opamp stage entirely - i mean, given that the output of the DAC is differential (aka balanced)._

 


 Some tweaks really improve this DAC. Have you seen this thread?


----------



## L_u_k_a_s

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_Just got one of these, and i have to say, boy, the quality. Where is it?!

 Pin 2 is lifted and bent over to pin 3 on the dac. Easy to fix, but, gives one the impression that these weren't inspected at all._

 

Actually, it is designer's intention. See this reply from seller to my questions about pins 2 & 3 and images attached.

 Reply from seller:
_hello, i have saw all my dac boards.all the boards are the same .

 and i asked the technican .

 they tell me that it isn't bad.

 it is designed like that.

 it is better .

 if you don't like that , you can change it by yourself._


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## ericj

Quote:


  Originally Posted by *L_u_k_a_s* /img/forum/go_quote.gif 
_Actually, it is designer's intention. See this reply from seller to my questions about pins 2 & 3 and images attached.

 Reply from seller:
hello, i have saw all my dac boards.all the boards are the same .

 and i asked the technican .

 they tell me that it isn't bad.

 it is designed like that.

 it is better .

 if you don't like that , you can change it by yourself._

 


 Yeah, I looked at pictures of 3 or so of these without that pin bent over before i posted here. 

 Also, reading the datasheet, I'm not sure what the idea behind it is. It looks like it just assures that the chip is in SPI mode if anything comes through the control port.

 Edit: Also, having read a few threads about this dac, I'd like to know what was 'better' about the network around the opamp serving only to increase the DC offset, and about the spdif input network being totally wonky.


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## L_u_k_a_s

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_Yeah, I looked at pictures of 3 or so of these without that pin bent over before i posted here. 

 Also, reading the datasheet, I'm not sure what the idea behind it is. It looks like it just assures that the chip is in SPI mode if anything comes through the control port.

 Edit: Also, having read a few threads about this dac, I'd like to know what was 'better' about the network around the opamp serving only to increase the DC offset, and about the spdif input network being totally wonky._

 

I guess it enables 96 and 192Khz sampling rates which are not working on boards without pin 2 lifted and pins shorted or modified in other way.

 For network around opamp - I skip entire output stage, take unbalanced signal directly from the DAC and use valve buffer. Then you need only +5V DC to supply the board. Or no output stage at all - just 2uF cap in series, then 47K resistor to gnd and 100R resistor in series.

 Wonky spdif - you mean loose conection on electrical? RCA is the worst connector for audio - analog and digital. I use 75 ohm BNC, preferably on both ends - source-cable and cable-dac. Or put DAC inside CD player and hardwire it.


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## ericj

No, enabling 96 and 192khz is a jumper between the spdif receiver and the dac. 

 Pin 2 is AD0 or CS depending on whether you're in i2c or spi mode. datasheet states "In i2c mode, AD0 is a chip address bit. CS is used to enable the control port interface in SPI mode. The device will enter SPI mode at any time a high or low transition is detected on this pin. Once the device has entered the SPI mode, it will remain until either the part is reset or undergoes a power-down cycle."

 That means that if pin 3 is anything but floating, and pin 2 is attached to it, the control port interface is in SPI mode. 

 Edit: Except, pin 16 is grounded, so we're in hardware mode - no control port.

 For pin 3 it states "in i2c mode, AD1 is a chip address bit. CDIN is the control data input line for the control port interface in SPI mode."

 Edit: looking at the schematic in post 33, pin 3 is tied to +3.3v, and if pin 2 weren't lifted and bridged over, it would be tied to ground. 

 What do you mean by "take unbalanced signal from the DAC"? - the DAC's output is balanced, the opamp is there to convert it to single-ended. 

 And no, I do not mean the RCA jack. I mean the input network just the other side of the RCA jack and TOSLINK receiver. Some posts on diyaudio complained that the values of the components are completely wrong.

 Edit: But it turns out i might mean something else entirely here.


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## ericj

Oh, I see what you're talking about with regard to pin 2 being tied high. Except, not really. 

 See here: diyAudio Forums - CS8416/CS4397 board at 96kHZ? - Page 1

 If i read the datasheets right, tying this pin directly to vcc means the dac is in 96khz mode all the time. 

 Which is most uncool, imho.


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## adamus

I have done a side by side with this dac and the cambridge audio dacmagic. The noodle dac has the opa2107 in it and has had its electorlytic output caps removed and replaced with obbligato. 

 The noodle dac is the better sounding dac to my ears by quite some distance. 

 for all its problems, it really agrees with my ears.


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## ericj

Yeah, that's why i bought it. Low price + a little labor for great performance. 

 "Most uncool" is responding to the problem of "You forgot to hook up the 96khz select pin on the receiver to the 96khz enable pin on the DAC" by forcing the dac to only accept signals over 50khz. fwiw there's no way for this receiver to tell this dac to accept signals over 100khz - for 192khz you'd need to lift both pins and attach some switches to manually select that mode. 

 If you plan on upsampling everything to 96khz, well, that's really not my style, but the "pin 2 lifted and shorted to pin 3" works. 

 Did you change any of the resistors and caps around the opamp socket?

 Stupid question: How is coax vs. optical selected?


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## fordgtlover

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_snip...

 Did you change any of the resistors and caps around the opamp socket?_

 

I have changed the PLL filter components (R2, C22, C23) with the values from this post, the R8, R9, R14, R17 (30K) and C32, C33, C34, C35 (150pF) for the output filter from this post, and the output mod from this thread.



  Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_Stupid question: How is coax vs. optical selected?_

 

Coax V optical is selected via the 3 pin header on my board, which is next to the 7 pin power connector.


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## ericj

OK. From the datasheet, there seems to be 4 inputs available in hardware mode, but it's clear as mud how they're selected. I'm considering cramming an M-Audio Sonica (like a Transit with no inputs) into the same enclosure, and would like to be able to switch usb/coax/optical. 

 Any ideas? 

 Thanks for the pointers, btw.


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## L_u_k_a_s

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_
 What do you mean by "take unbalanced signal from the DAC"? - the DAC's output is balanced, the opamp is there to convert it to single-ended._

 

Just connecting signal directly from R- and L- to the single ended valve buffer. Removed four capacitors after DAC so the whole onboard opamp output stage is not used.


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## ericj

So you mean you took the inverted signal. OK.


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## L_u_k_a_s

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_I mean the input network just the other side of the RCA jack and TOSLINK receiver. Some posts on diyaudio complained that the values of the components are completely wrong.

 Edit: But it turns out i might mean something else entirely here._

 

I'm back to post No. 169. What's wrong? I canť figure out whether caps are 0.01 μF, but otherwise, it is very nice - exactly how CS8416 datasheet suggests (chapter 16). For coax, it is C9 in series to RXP0 of receiver and R1 to gnd, for optical C7 in series to RXP1. Very short path. And RXN connected to C24, which goes then to gnd. There are other components connected to RXP5, I believe it is only "logic" for switching between RXP0 and RXP1 (coax and toslink) input (R7 - value 10R and R24 - value 1K are part of this logic).

 Yesterday I put this little board inside CD player, it steals +5V DC (opamp output stage not used) from CD player board and has 4 inputs - 3 electrical spdif (from CD, external BNC, external coax) and toslink - conveniently selected with 2 pole 4 position switch, as well as BNC out passthrough. One pole of switch chooses electrical input and other pole takes care about logic electrical/optical. I put it inside smallish player just 27 cm wide and 7 cm high, can post some images if someone interested. I have only this crappy photo from outside. First I wanted to use I2S connection from CDp to DAC, but I'd have to solder directly to pins of chips and possibly break something. So I used spdif as if it were external DAC.


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## ericj

I mean the PLL filter network on the cs8416 - R2, C22, C23. The values are from an old version of the datasheet, the new version has a much better configuration. Described here: 

CS4397 dac - The Art of Sound Forum

 Also, since we're in hardware mode rather than software slave mode, there is no RXP5.


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## ericj

wow, I've really had this board 18 months?
   
  I finally started reworking it today.
   
  Friendly advice: Be careful and mindful when desoldering the smd parts. I accidentally took off R13 and didn't notice that i wasn't supposed to have done that for 20 minutes.
   
  I found all sorts of little smd parts on the workbench, but guess what value resistor i still haven't found, over an hour later


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## ericj

So, I found my missing resistor: 
   

   
  Next up:
   

   
  I know the opamp resistors aren't necessary if i use transformer output, but i want to be able to compare the opamp output with the transformer output.
   
  The edcors, fwiw, cost $19 shipped for the pair.


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