# Dynalo (Rev.C) construction thread



## steinchen

while populating the Rev.C board some questions have been coming up to me. Since I haven't been able to find the answers by the documentation or by the search function I consider it a good idea to start a construction thread like the ones for PPA v2 and M³

 1) R67 = RLED and should be (depending on the LED used) about 4k, right ?
 2) the spec for C27 / C28 is missing. I can't find that small polypropylens, even styroflex types are starting at 47pF, polys much bigger. Should I go for the 47pF styro or pick ceramic caps ?
 3) R65 ? R66 ?
 4) how to wire a volume control pot to the amp ?
 5) under what circumstances should I consider to populate the optional 20k pots for R63 / R64 ?


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## phobus

Quote:


  Originally Posted by *steinchen* 
_1) R67 = RLED and should be (depending on the LED used) about 4k, right ?
 2) the spec for C27 / C28 is missing. I can't find that small polypropylens, even styroflex types are starting at 47pF, polys much bigger. Should I go for the 47pF styro or pick ceramic caps ?
 3) R65 ? R66 ?
 4) how to wire a volume control pot to the amp ?
 5) under what circumstances should I consider to populate the optional 20k pots for R63 / R64 ?_

 

I'm sure others are more qualified but here goes:

 1) yup
 2) I think these are the compensating caps? I think they're supposed to be 5 or 10pf mica ones. I left mine unpopulated.
 3) for testing. You can stick 10k resistors in there when testing for offset.
 4) I did it: rca input -> pot -> input on board.
 5) dunno


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## bg4533

R65 and R66 go to ground. Should be 5-10 times the value of the pot. I used a 50k pot and 1M resistor since it is what I had.

 I used 10k LED for the resistor. Value depends on the LED. I believe Tangent has a calculator on his site.

 Wire the pot to the input. RCA signal to pot. RCA ground to pot and board. Pot output to board.

 edit:
 hmmm...so am I wrong about the use of R65 and R66? If so I will remove it so I don't confuse others.


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## bg4533

Someone will ask eventually so...

 Info on changing the gain and making a gain switch: link


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## steinchen

thanks dudes 
	

	
	
		
		

		
		
	


	




 for matching transistors take a look at
http://www6.head-fi.org/forums/showthread.php?t=91235
http://www6.head-fi.org/forums/showthread.php?t=93115 

 if c27 / c28 doesn't need to be a film type the recommendation goes to silvered mica and Kemet Golden Max I guess

 R67: when using a low current LED (2V 3mA) a 10k resistor will fit, with a high current blue LED (3V 10mA) you'll need a 3k 0.5W resisitor 

 R65 / R66: 5-10 times the value of the pot sounds reasonable and meets the recommendation for the PPA amps


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## bg4533

I didn't use C27/C28. Everything is fine. No oscillation.

 What are these caps for?

 Can someone post some part numbers?


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## steinchen

10pF 200V 5% Kemet Golden Max digikey #399-1888-ND
 10pf 500V 5% Mica digikey #338-1061-ND


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## Pars

Quote:


  Originally Posted by *bg4533* 
_R65 and R66 go to ground. Should be 5-10 times the value of the pot. I used a 50k pot and 1M resistor since it is what I had.

 edit:
 hmmm...so am I wrong about the use of R65 and R66? If so I will remove it so I don't confuse others._

 

I don't think they are necessary if you are using a pot. These pads were provided if you DON'T use a pot. If that's the case, they should have something around 0.5 Meg in there. As you said, putting in low values can be used for testing (like 47-100 ohms), which effectively shorts the inputs. I have 475K in my Rev. B board right now until I get around to casing it up and putting a pot in.

 Dan or anyone? Any different opinions?

 -Chris


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## amb

Quote:


  Originally Posted by *Pars* 
_I don't think they are necessary if you are using a pot. These pads were provided if you DON'T use a pot._

 

I recommend populating R65/R66 anyway, at least 10x the value of the pot. This is in case the pot's wiper loses contact, the input FET would not lose its bias path to ground and cause a big DC offset.

 About C27/C28, these are compensation caps for taming a minor overshoot in the square wave response.


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## Pars

Quote:


  Originally Posted by *amb* 
_I recommend populating R65/R66 anyway, at least 10x the value of the pot. This is in case the pot's wiper loses contact, the input FET would not lose its bias path to ground and cause a big DC offset._

 

Good to know, although I would think that to be unlikely. Nonetheless, cheap insurance. Guess I will populate the equivalent position in the headamp V2 board that I am currently using.

 BTW, the compensation caps were suggested by Stackofhay at 33pf for the stock gain, less if you reduce the gain. He used the CDC micas from Mouser.

 Thanks for the input Amb.


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## amb

Quote:


  Originally Posted by *Pars* 
_BTW, the compensation caps were suggested by Stackofhay at 33pf for the stock gain, less if you reduce the gain._

 

Actually I think it's just the opposite... you would use less capacitance if the gain is _higher_. This is because the GBP of the amp is essentially constant wrt. gain, and as you increase the gain, you need less capacitance to achieve the same corner frequency and phase margin.


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## bg4533

Has anyone else built a Dynalo in the Hammond case listed in the BOM?

 When mine has been in use for many hours it gets pretty warm. Maybe too warm. I need to take some temperature measurements. I just wanted to warn people of this.


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## skyskraper

try taking temp measurements of the case, transistors in case, without lid, etc. iirc i measured a rise of like 4c with my dynalo in a 1ru rack case, not a huge rise at all.

 how much extra space is there between the transistors and the lid of the case? maybe you could stick a low profile heatsink on top of them if it really is bad?


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## BrokenEnglish

Quote:


  Originally Posted by *steinchen* 
_2) the spec for C27 / C28 is missing. I can't find that small polypropylens, even styroflex types are starting at 47pF, polys much bigger. Should I go for the 47pF styro or pick ceramic caps ?_

 

reichelt.de stocks 10pf, 22pf, 33pf "glimmer" caps, steinchen... specwise they are hard to beat... not quite cheap though...


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## steinchen

Glimmer caps are in fact Mica caps. Just wondered if c27/c28 need to be film or ceramic. I think I got some spare 10pF Kemet Golden Max and silvered mica caps left over from my M³ build. I will take a look in my box and let availability decide.


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## amb

Compensation caps must have good HF characteristics, multilayer ceramic and silver mica types are both appropriate.


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## BrokenEnglish

Quote:


  Originally Posted by *steinchen* 
_Glimmer caps are in fact Mica caps. [...]_

 

oh... just learned another cryptic diy word... thanks!


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## SnoopyRocks

Now that I've finally found some free time 
	

	
	
		
		

		
			





, I'm ready to order parts for a couple of boards.

 Could some kind soul recommend sockets for transistors, preferably with a mouser or digikey part number? Something similar to what dgardner uses here would be great.

  Quote:


  Originally Posted by *amb* 
_Actually I think it's just the opposite... you would use less capacitance if the gain is higher._

 

You can stop thinking - you're right.


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## skyskraper

i dont have a mouser or digikey number but any snap off single row socket set will work. they usually come in 40 pin rows 
	

	
	
		
		

		
		
	


	




 check the pdf catalog's of the stores to find em, heaps better then searching the sites


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## amb

Quote:


  Originally Posted by *SnoopyRocks* 
_Could some kind soul recommend sockets for transistors, preferably with a mouser or digikey part number? Something similar to what dgardner uses here would be great._

 

As far as I could tell the TO-92 transistors on his board are all on break-apart SIP sockets (like these). I am curious about the ones the dual-JFETs are plugged into, however.


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## bg4533

Quote:


  Originally Posted by *SnoopyRocks* 
_Now that I've finally found some free time 
	

	
	
		
		

		
		
	


	




, I'm ready to order parts for a couple of boards.

 Could some kind soul recommend sockets for transistors, preferably with a mouser or digikey part number? Something similar to what dgardner uses here would be great.

 You can stop thinking - you're right. 
	

	
	
		
		

		
		
	


	


_

 

Mouser socket link 
 I think you can order those in strips with different numbers of pins. Either way break off the number you need.

 I believe the sockets Dan used for the dual fets were old and obscure. He posted about them somewhere. I havent checked spacing, but you might be able to use a row of 4 and a row of 3 of the SIP sockets.


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## SnoopyRocks

Wow. That was quick! Thanks guys.


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## Pars

The sockets that Dan used for the FETs are actually Zig Zag sockets, something like Digikey ED2220-ND (MillMax). I got a couple of samples of the 28 pin version of these, and they are easy to cut apart into 7 pin sockets, and fit better than 2 rows of SIP sockets do. The SIP sockets I used are the MillMax, Digikey part ED7064-ND (64 pin). I like these better than the other SIP sockets I have tried (Aries).

 On Dan's boards, the middle of the 3 pins for the FETs does not have a hole, so really you need (2) 3 pin (2-1) sockets, or you can drill a hole for the middle pin, or just clip the tail on that one.


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## dgardner

Quote:


  Originally Posted by *Pars* 
_The sockets that Dan used for the FETs are actually Zig Zag sockets, something like Digikey ED2220-ND (MillMax). I got a couple of samples of the 28 pin version of these, and they are easy to cut apart into 7 pin sockets, and fit better than 2 rows of SIP sockets do. The SIP sockets I used are the MillMax, Digikey part ED7064-ND (64 pin). I like these better than the other SIP sockets I have tried (Aries).

 On Dan's boards, the middle of the 3 pins for the FETs does not have a hole, so really you need (2) 3 pin (2-1) sockets, or you can drill a hole for the middle pin, or just clip the tail on that one._

 

I just cut the zip socket to size then turn it over and push the middle pin out of the socket body with a nailset.


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## dgardner

I have been working on a Dynalo Rev C Detailed Construction Guide, but I just can't seem to get the darn thing totally ready. It's about 90% complete. If anyone is open to reviewing a draft copy as possibly adding some content, please PM me.


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## amb

Quote:


  Originally Posted by *Pars* 
_The sockets that Dan used for the FETs are actually Zig Zag sockets, something like Digikey ED2220-ND (MillMax)._

 

Thanks for the pointer!


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## palchiu

Finish my first DIY headamp, but questions is how to measure and adjust. 
	

	
	
		
		

		
		
	


	




 I follow measure with this diagram, I've adjust the voltage as this.






 But, I measur the output there were different voltage from left and right.

 Any one can help? Thanks!!!


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## Pars

Quote:


  Originally Posted by *palchiu* 
_Finish my first DIY headamp, but questions is how to measure and adjust. 
	

	
	
		
		

		
		
	


	




 I follow measure with this diagram, I've adjust the voltage as this.






 But, I measur the output there were different voltage from left and right.

 Any one can help? Thanks!!!_

 

When you say the output was different, I assume you mean the DC offset on the output, measured with inputs shorted to ground? What readings are you getting here?

 In a discrete amp such as this, irregardless of how well you match everything, there will be some difference between channels. If you are measuring 10mV or lless on each channel without the servo opamp installed, you are in good shape. Otherwise, it may be necessary to change out LEDs, put a pot in parallel with the 500 ohm input resistors, or other steps in order to bring the offset down. The voltage measurements that you showed on your drawing are only a guideline to determine proper component and amp operation. Getting DC offset as close to 0 mV as possible is the real goal, and should be the predominate measurement that you use when adjusting anything in the circuitry.


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## dgardner

Dynalo - Detailed Construction (dgardner 5-7-2005).doc (2.59MB)
Dynalo - Detailed Construction (PARS Edits).doc (2.57MB)
Dynalo - Detailed Construction (STACKOFHAY Edits).doc (2.61MB)
Dynalo - Operating Points.pdf (131KB)

 We are now entering the community editing phase of the project. 
	

	
	
		
		

		
		
	


	




 Thanks to everyone who has contributed to the edits so far. I fear this will never be completed if I don't just post is here raw and let everyone run with the edit process.


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## grasshpr

Quote:


  Originally Posted by *dgardner* 
_Dynalo - Detailed Construction (dgardner 5-7-2005).doc (2.59MB)
Dynalo - Detailed Construction (PARS Edits).doc (2.57MB)
Dynalo - Detailed Construction (STACKOFHAY Edits).doc (2.61MB)
Dynalo - Operating Points.pdf (131KB)

 We are now entering the community editing phase of the project. 
	

	
	
		
		

		
		
	


	




 Thanks to everyone who has contributed to the edits so far. I fear this will never be completed if I don't just post is here raw and let everyone run with the edit process._

 

Great job Dan! You might want to add that it would be recommended to do soldering with some form of vise, e.g., one of those Panavise circuit board holders. 

 Not a necessity but would make putting components on the board Extremely easy! Also, it might be useful to mention that you can use masking tape to hold chips or components to the board instead of bending the leads to make them stay put. I'm always weary that by bending leads I might accidentally short items by accident. Its also easier to put on since tape can be placed to hold many items at a time (and could be reused when having to put new items in). Just a suggestion to aid newbie's out


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## palchiu

Thanks everyone!


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## SnoopyRocks

I just finished two amps. A lot more debug time than I anticipated was necessary because I mistakenly ordered 24.9k instead of 24.9 Ohm resistors for the output stage. What really irks me is that I measured _every_ single one by hand and still missed the little 'k' on the DMM _each_ time. Sometimes you only see what you want to see. 
	

	
	
		
		

		
		
	


	




 After swapping in resistors with the closest values available at hand (20 Ohm) and adjusting R19 to get the output current right, everything works.

 Here are some of my observations:
They sound great - better than a pimeta (OPA627s, dual stacked buffers, tread, class A). Critical listening was not necessary to discern the distinctions, but I did have to AB to tell. The biggest difference is the in the bass, which is deeper, faster and clearer. Clarity has improved and I hear detail (such as smoother decay, lusher reverb, etc) that I had not before, which is really encouraging because this is apparent even with low bit rate mp3s with an audigy 2 zs upsampled to 24/96 in software with kernal streaming as a source. What was most surprising was that even when it was not working properly (high output impedance due to large output stage emitter degeneration resistors and very low output current), it still sounded better than an iPod Mini by itself, albeit with low volume. 
	

	
	
		
		

		
		
	


	





The pimeta measures MUCH better - linearity in particular (~20dB better SFDR). MCM sent pnps and npns from different gain classes, making matching problematic since the pnp Betas measured around 175 +-15, while the npn Betas measured around 250+-10. I'd like to test again with better matching if I can get some higher gain pnps or lower gain npns. Socketing the transistors sure was a great idea.
The open loop gain was lower than expected but made sense after thinking about it. Here is where the thermal tracking diodes hurt. I measured an actual closed-loop gain of 2.8 for a feedback factor of (1/4). This translates to an open-loop gain of about 10. I wonder if the JFETs' gm is lower than expected because of low IDss as well...
LED matching matching was not as big a deal as I anticipated, especially with the trimpots.
Offset was not hard to get reduce. The AD820 works well as a substitute for the OP27 with lower power consumption. Typical measured offsets were less than 1mV after settling. Using the servo makes thermal bonding diodes superfluous (IMO) and considering the reduced open-loop gain, I would skip the diodes next if I were to do it over again.
Casework is not particually fun and is difficult to get just right. It's off just enough to bother me, but would take a sharp eye to catch. Ughh...I miss having access to a propper machine shop.

 Has anyone else, measured the performance (THD, SNR, etc) of their build or observed the low open-loop gain that I have?

  Quote:


  Originally Posted by *bg4533* 
_Has anyone else built a Dynalo in the Hammond case listed in the BOM?

 When mine has been in use for many hours it gets pretty warm. Maybe too warm. I need to take some temperature measurements. I just wanted to warn people of this._

 

I did use the Hammond case from the BOM but don't think that it gets hot. IMO, this is a nonissue.


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## amb

Quote:


  Originally Posted by *SnoopyRocks* 
_The open loop gain was lower than expected but made sense after thinking about it. Here is where the thermal tracking diodes hurt. I measured an actual closed-loop gain of 2.8 for a feedback factor of (1/4). This translates to an open-loop gain of about 10._

 

The gain of the Vas stage is actually less than unity (according to Kevin Gilmore, it's 0.5, and my calculations agree). The gain of that stage could be increased slightly by upping the value of the two 3.3K resistors going to ground at the collectors of the Vas transistors (or even remove those two resistors altogether, which only increases the gain of that stage to a little more than 0.6 by my calculations). Kevin states that the first stage has a gain of 50, which seems higher than what you actually measured. Decreasing the value of the 200 ohm resistors at the source pins of the input JFETs should give that stage a boost. While I agree with Kevin that too much open loop gain is not desirable, as it stands the open loop gain is probably too low. Changing those resistors to 100 ohms looks like a good mod to try.


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## nikongod

here are a couple quickies:

 1: are the 2 heatsinks necessary? i saw a build that lacks them on the "post your builds page"

 2: how rigidly set are the capacitor selections? im assuming not very, and hoping this to be correct. obviously type should be same (dont put an electrolytic where a film belongs...) but what about sizes?

 thank you much


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## palchiu

I think if your case have venting hole, there no need these heatsinks.

 I've burn the dynalo for 72 hours, they are not hot. My finger still can touch they and feel warm.

 But the best way is put them on, maybe will extends they life.


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## robzy

20 - CAP - Monolithic Ceramic - 0.33uF, 25V or greater7.5mm - P4669-ND - C5, C18 

 Hey there, in the BOM it mentions the above capacitor, problem is the part number it mentions is not a Monolithic Ceramic but is actually a polyster film, should i go with poly film? or ceramic?

 Rob.


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## dgardner

Quote:


  Originally Posted by *robzy* 
_20 - CAP - Monolithic Ceramic - 0.33uF, 25V or greater7.5mm - P4669-ND - C5, C18 

 Hey there, in the BOM it mentions the above capacitor, problem is the part number it mentions is not a Monolithic Ceramic but is actually a polyster film, should i go with poly film? or ceramic?

 Rob._

 

This cap is the integrator for the DC offset servo. The type is not especially critical. Film caps are fine. Try to stay close to the 0.33 value or slightly larger.


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## sft

Quote:


  Originally Posted by *palchiu* 
_I've burn the dynalo for 72 hours, they are not hot. My finger still can touch they and feel warm.
_

 

had better make sure the bias current is near 16mA. The output transistors are hot after 1 hour.


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## palchiu

Thanks SFT!!! I'll check it again.


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## robzy

R65 & R66? What should i do if im using a 50k pot? Im totally confused.

 [edit]: And for the 100uf electrolytics, all the BOMS i have state them as 25V or greater, but the Detailed Construction Guide i am using says 120uf 35v minimum.... so which is it?

 Rob.


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## amb

Quote:


  Originally Posted by *robzy* 
_R65 & R66? What should i do if im using a 50k pot? Im totally confused._

 

Use a resistor value about 10x or more of the pot, so that the resistor doesn't alter the pot's taper adversely. If you're using a 50K pot, then use 470K to 1M ohm for these resistors. The purpose of these resistors is to prevent the JFETs' gate from floating (and losing bias) if the pot should ever become intermittent. That could cause headphone-damaging DC offset to develop.


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## robzy

Thanks for that 
	

	
	
		
		

		
		
	


	




 Hopefully i have one lying around.

 [edit]: And just to reiterate my other question (now that its on the previous page: And for the 100uf electrolytics, all the BOMS i have state them as 25V or greater, but the Detailed Construction Guide i am using says 120uf 35v minimum.... so which is it?

 Rob.


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## amb

Quote:


  Originally Posted by *robzy* 
_for the 100uf electrolytics, all the BOMS i have state them as 25V or greater, but the Detailed Construction Guide i am using says 120uf 35v minimum.... so which is it?_

 

These are on the supply rails which don't normally get more than +/- 15V or 16V, so 25V caps are adequate. But, going to 35V caps ensures that if, for whatever reason (a weird failure or short circuit), the whole difference in voltage between the positive and negative rail were to become present on one of these caps (which would be 30V or 32V), then it would still survive. Since electrolytic caps often fail by exploding into a big mess, some voltage headroom is a good idea.


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## robzy

That makes sense, thanks a lot 
	

	
	
		
		

		
		
	


	




 So now that im getting new caps i decide taht getting ones with the right pitch diamater would be a good idea.

 Problem is that the 100v Pana FMs have 5mm pitch... but a minimum order of 10 @ $2 each aint cheap... i guess ill just go for the 35v ones.

 Rob.


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## Garbz

I don't think the value of the caps is too much of an issue. The output of the power supply if leads are kept short should provide appropriate current reasonably quickly.

 Personally I've gone overbaord putting 6x 470uf 16v caps on each board.


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## robzy

Quote:


  Originally Posted by *Garbz* 
_Personally I've gone overbaord putting 6x 470uf 16v caps on each board._

 

16v caps? Aint that cutting it a bit close?

 And wow, 470uf? Thats quite a bit 

 Rob.


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## Garbz

it is seeing how there's 16.5v going into them. But so far every dynalo i built has survived. I doubt the caps will survive for their rated life span though. Plus 25v ones didn't fit


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## robzy

25v ones that dont fit? Im going up to 50v/100v so that the lead pitch is 5mm, what caps are you using?

 Rob.


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## Garbz

16v 470u Elna Simlics. The 25v 470u don't fit. But I believe the 220u do. Pity they aren't stocked where i'm shopping.


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## bg4533

I used 220uf/25V Silmic IIs in a Dynalo. 100uF/25V Silmic IIs in another. 470uF/25V Cerafines will also fit fine.


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## robzy

Bugger boutique caps, im just gonna go with high voltage FCs... 

 Mmm... its soo close to being done 
	

	
	
		
		

		
		
	


	




~~

 Rob.


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## silvalis

Are there any other recommended alternate BJTs to replace the 2SA1015 & 2SC1815 other than MPS8099/8599?


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## amb

Quote:


  Originally Posted by *silvalis* 
_Are there any other recommended alternate BJTs to replace the 2SA1015 & 2SC1815 other than MPS8099/8599?_

 

Reasonable substitutes are BC327/337 or BC550C/560C. Note that these have different pin-outs than the 2SA1015/2SC1815, so you will have to orient them on the board differently.


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## nikongod

i recall reading that there is a pair of resistors to replace with a trimpot to eliminate/reduce the need for transistor matching.

 anyone know which pair?

 also, am i correct in my assumption that this can be COMBINEd with the dc offset servo? i hope to finish my build, dial in (servo not connected) and then connect the servo. after that the servo will have a minimum of work to do only correcting for parts that age, and whatnot.


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## dip16amp

Quote:


  Originally Posted by *nikongod* 
_i recall reading that there is a pair of resistors to replace with a trimpot to eliminate/reduce the need for transistor matching.

 anyone know which pair?

 also, am i correct in my assumption that this can be COMBINEd with the dc offset servo? i hope to finish my build, dial in (servo not connected) and then connect the servo. after that the servo will have a minimum of work to do only correcting for parts that age, and whatnot._

 

The 500 ohm resistors.


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## nikongod

you =the man. 

 i bet there are even pads on the board for that specfic purpose...

 edit: a further inspection of the board, and schematic reveals that indeed pads for just that do exist. bonus round.


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## robzy

Surely putting those pots in the signal path arent a great idea...

 Rob.


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## Garbz

define signal path. I wouldn't use these pots as a volume control, but here they are only really adjusting the bias current for an LED.


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## robzy

*thinks*

 Sorry, you are right 
	

	
	
		
		

		
		
	


	




 Rob.


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## DigiPete

Hi folks,

 Got the dynalo amp to the startup stage. I had +5mv and -5mv initial dc offset. I then zeroed it out with the trim pots.

 I used a 100 ohm resistor for r19 and 1kohm for r16, trying to get a gain of 11. The voltage across r19 is 0.417v, voltage across r23 etc is about 0.227v, these do not match the guide...

 Then I put in the opamps and the offset steadily rises to about 3+ mv after about 10 minutes. Is this normal or should it regulate down below 2 or 1mv?

 Any suggestions.

 Also, for the dynahi psu, do the regulators need to be electrically isolated from the heatsink(i.e. from each other). If so, what insulator do you use to do this?

 Thanks 
 Pete


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## dgardner

Glad to see your getting closer.. 

 R19 and R49 need to be 200 ohms. They do not set the gain. Don't change the value. If you used 100 ohms in these locations, the output is not running properly. Slow movement just above and below 0v during operation is normal.

 For a gain of 11, set (R16,R46) to 10K, and (R7,R37) to 1K. Make sure (C27, C28) has a 10pF cap in it.

 The servo behavior sounds normal, but if your resistors in R19 and R49 are not 200 ohms, I can't predict the results easily. I typically see +/- 2 to 3 mV worst case.

 As for the PSU, all parts on the heatsink must have insulators. If you don't insulate, the parts WILL smoke.


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## CB600F

Hi there,

 << Finally I started an electronics project again. It has been a while. >>

 Has anyone been fiddling around with the dynalo and the SWCAD III Spice simulator? (Or any other spice simulator for that matter)
 I have just started with my first simulations and it seems to simulate the amp pretty well. I tried some other transistors like the bc547b; no shocking differences there. I thought the opamp would make a difference, but after adjusting simulation resolution there was no noticeable difference.

 Regards,

 David


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## sbelyo

Does anybody have digikey or mouser part number for:

 C6, C7, C19, C20 

 C1, C2, C3, C4, C12, C13, C14, C15, C16, C17 

 C10, C11, C21, C22 

 I just want to make sure they fit and are the right type. I'm starting to gather parts this weekend.


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## grasshpr

These are mouser part numbers:

 C6, C7, C19, C20 -> 581-SR205C104KAATR
 C1-4, C12-17 -> MKT1817410064
 C10, C11, C21, C22 -> 5989-100v4.7


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## bg4533

Quote:


  Originally Posted by *grasshpr* 
_C6, C7, C19, C20 -> 581-SR205C104KAATR_

 

Minimum order of 3000 on that part


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## grasshpr

OOps. Must of changed recently. I had the same part number when I bought a few when I made my dynalo. Sorry, at least you have something to compare with 
	

	
	
		
		

		
		
	


	




 Thanks for pointing that out bg4533, I surely won't purchase that item again.

  Quote:


  Originally Posted by *bg4533* 
_Minimum order of 3000 on that part 
	

	
	
		
		

		
		
	


	


_


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## grasshpr

Here's a similar part from digikey which doesn't have a minimum purchase of 3000! 

 399-2081-ND

 Sorry for the confusion.


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## dip16amp

Mouser also has this: 581-SR205C104K and 581-SR205C104KAT


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## sbelyo

Thanks guys...

 I'm planning on matching the transistors with my multimeter's hfe setting. Beyond that I'm hoping using the 1K pots in place of the 2 499 ohm resistors and switching LED's I should be in good shape.


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## bg4533

Quote:


  Originally Posted by *sbelyo* 
_Thanks guys...

 I'm planning on matching the transistors with my multimeter's hfe setting. Beyond that I'm hoping using the 1K pots in place of the 2 499 ohm resistors and switching LED's I should be in good shape._

 

I read somewhere here that matching these transistors with your multimeters hfe setting might be worthless. Multimeters generally use less than 1ma to test hfe while the transistors will see between 2ma and 16ma in normal use. 

 Transistor matching is ideal, but not necessary if you use the trim pots. Just make sure you have transistors from the same class


----------



## Pars

Quote:


  Originally Posted by *bg4533* 
_I read somewhere here that matching these transistors with your multimeters hfe setting might be worthless. Multimeters generally use less than 1ma to test hfe while the transistors will see between 2ma and 16ma in normal use. 

 Transistor matching is ideal, but not necessary if you use the trim pots. Just make sure you have transistors from the same class_

 

Fortunately these transistors are rather linear across the required Ic range. I have done extensive matching via a test fixture only to have to tweak the resistances/LEDs to get acceptable offset, so I'm certainly not going to say that matching is imperative to get an operable amp. However, I do believe that the better you match stuff, the less you have to deal with down the road and I personally don't trust trim pots... worked too long as a tech in the semiconductor industry to trust them not to drift 
	

	
	
		
		

		
		
	


	




.

 I think the most rational approach to building a Gilmore-type architecture was that of Stackofhay's (geoff... where is he these days anyhow?). He used a pot initially, but only to get a general resistance value. Then I believe he used a decade box with the pot out to dial in the values required, then put in fixed resistors as close as he could get to those values. Of course everyone does not have a decade box nor tons of fixed precision resistors laying around to make up the right values (or paralleled values). I still think its the right approach however. But then again, I am an idealist... 
	

	
	
		
		

		
		
	


	




 just my devalued $0.02

 Chris


----------



## dgardner

Another thread supporting construction questions on the Dynalo Rev C project is here.


----------



## sbelyo

I thought I might be able to do domething similar by socketing the two pots (or positions) at the top. Then once the offset is adjusted I would remove the pot and take a reading to see what it's value is. Then replace it as close as I can with a rn60d. I only have to order 9 values to cover what's in between 499 Ohm and 1.0K I also just went through my resistor box and pulled out 11 rn60d's that are already needed. So at least my part cost wont go up that much.


----------



## sbelyo

I'm going to build this on some proto-board tonight and then match the transistors that I just matched with my multi meter using the hfe setting.




 It's just a schematic without the transistor symbol. I drew it with E for emitter B for base and C for collector. The value I took from gilmore's original project in headwize. I hope it's right


----------



## sbelyo

I built the circuit and I suppose it works. All of the pairs were within 0.01 Volts of each other ( most were a dead match). It gave me the same results as the hfe setting on my meter.

 I also went back to the old ones that I couldn't match up and all their numbers were at least 0.10 apart.

 Also a side question... I accidentally put some of them in backwards and got a higher voltage reading. I re-tested them and they all stayed the same values as before. Could they be damaged by doing that?


----------



## robzy

Couple of quick questions - what resistors should i be choosing for a gain of slightly over 3? And what would the appropriate C27/C28 compensation-cap value be?

 And what type of cap should c27/c28 be? Anything but ceramic?
 [edit2]: Nevermind, every oine of those have already been answered further up in the thread.

 Thanks,
 Rob.

 [edit]: And what are the spacing on the mounting holes on the PCB?


----------



## Vadi

I want to build the Dynalo. 
	

	
	
		
		

		
			




 I downloaded the docs off djgardner's page. 
 At Digikey I see two kinds of OPA227s and their specs seem to be identical: 
 OPA227P-ND at 4€ 
 OPA227PA-ND for 2€ 
 Which should I use? 

 Also how can I accomplish 
 "Use a (2SK389 2SJ109) pair in the same Gain Class with Idss matching. (ideal)"? I only have a cheap multimeter. 
 If that's too complicated there is the easier option of using pairs of the same gain class. 
 The doc says I may want to try a few combinations. What exactly should I try out? 

 Regards, 
 Sladi 


 edit: 
 Is this revision still without any capacitors in the signal path?


----------



## Pars

Quote:


  Originally Posted by *Vadi* /img/forum/go_quote.gif 
_I want to build the Dynalo. 
	

	
	
		
		

		
		
	


	



 I downloaded the docs off djgardner's page. 
 At Digikey I see two kinds of OPA227s and their specs seem to be identical: 
 OPA227P-ND at 4€ 
 OPA227PA-ND for 2€ 
 Which should I use? 

 Also how can I accomplish 
 "Use a (2SK389 2SJ109) pair in the same Gain Class with Idss matching. (ideal)"? I only have a cheap multimeter. 
 If that's too complicated there is the easier option of using pairs of the same gain class. 
 The doc says I may want to try a few combinations. What exactly should I try out? 

 Regards, 
 Sladi_

 

I would not use the OPA227, instead just use TL071s. The OPAs for me would not zero out negative voltages whereas the TL071s will. OPA132 / 134s supposedly work well also. These are just DC servo opamps, so nothing crazy is required. FET input is probably better.

 As for Idss matching the FETs, even a cheap DMM is sufficient. As far as how to match them, check earlier in this thread, or do a search here for matching.

 You will have a very hard time finding 2SK389 / 2SJ109s as they were discontinued and command a hefty price if you can find them. Dan Gardner did have some available, so I would send him an email. If no luck on those, the single equivalent FET is the 2SK170 and 2SJ74, respectively. BL would be a good Idss range to try to find, but just make sure you get the same range (see the datasheets for the different range suffixes). Get more than you need (double, remember that you need two of these for a single 389 or 109).


----------



## Vadi

Thanks Pars! 
	

	
	
		
		

		
		
	


	



 I forgot to ask about the thermal compensation option. Should I use it? I ask because I read in some thread that it causes some problems.


----------



## Pars

I didn't notice much difference with or without it on my test board. Unless you can tightly bond the diodes to the output transistors, it probably won't make a difference. I wouldn't bother with it. Are you using one of the group buy boards? It does have provisions for it, so it is easy to add (or remove) later.


----------



## Vadi

Thanks Pars. 
 I don't have a board at all. I sent dgardner a PM. 
 I hope there are still some boards around.


----------



## bidoux

Does anyone know a cheap power supply that is already built and would work well with the Dynalo (it would be cheaper than the dedicated PSU and anyway I don't want to work with that kind of voltage) ? 
 I think Uncle Erik mentionned the Elpac but I'm not sure which one exactly. Thanks for your help head-fi !
 PS: I'm not looking for any high end, the cheaper the better.


----------



## FallenAngel

Can't get much better/cheaper than dual TREAD.


----------



## kvant

_> mentionned the Elpac_

 I think the part number is WM071-1950-D5 (+/-15V @ 240mA). Mouser and Allied seem to have some stock. These power supplies look a little pricey, but if you buy a transformer, enclosure and some parts, you a likely to hit a similar price point too.


----------



## bidoux

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Can't get much better/cheaper than dual TREAD._

 

But I would have to deal with 220V, wouldn't I ? Don't want to die because I wanted my DT880 to sound a bit better...

 @kvant: thanks for the part number, but this make me worry a bit: 
 Voltage - Input108 ~ 132VAC, I live in France so input would be more like 220.
	

	
	
		
		

		
		
	


	




 I appreciate you help a lot, thanks !


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_...but this make me worry a bit: 
 Voltage - Input108 ~ 132VAC, I live in France so input would be more like 220.
	

	
	
		
		

		
		
	


	


_

 

I am sorry, I missed that you are from France. This Elpac power supply is not a solution for you then. Perhaps some manufacturer in Europe makes something similar...


----------



## bidoux

too bad.
 I will take a closer look at FallenAngel's solution. Do I have to find an extra simple wall wart (with only a Transformer in it ?) that provides +16 and -16 and add two Tread with it ?
 What is the diode bridge of the Tread for in this case ?


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_...wall wart (with only a Transformer in it ?) that provides +16 and -16 and add two Tread with it ? What is the diode bridge of the Tread for in this case ?_

 

A wallwart with just transformer in it would have alternating voltage on output (therefore no +/-16V terminals), which would be a reason for some rectifier. An AC wallwart with 220V conveniently sealed is very attractive in your situation, but (surprise) there is a catch. The dual TREAD plan  requires dual secondary and you are not likely to find a wallwart that would offer that. You could use two identical wallwarts, but that is rather impractical.

 If you could get a wallwart with a center tap (three terminal output), you could just use it in place of a transformer in a traditional single bridge dual rail supply. Unfortunately, wallwart with a center tap is also not a very likely find.

 You can try the the following circuit:






 It uses a common two-terminal AC wallwart. The capacitors between diodes and regulators need to be quite large, since the diodes implement only half-wave rectifiers (positive half of the AC waveform goes to positive rail and negative to negative rail). The 15VAC input shown is close to minimum, 20VAC would probably be close to maximum. If you go with more than 15VAC, increase voltage rating of the capacitors before regulators to 35V.


----------



## bidoux

That seems to be a nice solution, not any issue with the Dynalo ? But I think 16V for the second capacitors (470) is a bit low when working with 15 V knowing i have usually a LOT
	

	
	
		
		

		
		
	


	




 of tolerance in my capacitors...

 BTW why are there differents outputs on this schems ?why 48, 24 and 16 ? i thought Dynalo only accepted +16V and -16V


----------



## Pars

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_That seems to be a nice solution, not any issue with the Dynalo ? But I think 16V for the second capacitors (470) is a bit low when working with 15 V knowing i have usually a LOT
	

	
	
		
		

		
		
	


	




 of tolerance in my capacitors...

 BTW why are there differents outputs on this schems ?why 48, 24 and 16 ? i thought Dynalo only accepted +16V and -16V 
	

	
	
		
		

		
		
	


	


_

 

Those are test voltages. Most people actually built this supply (Headamp included on the Gilmore V1 and V2 amps) using 2x18VAC transformers (Amveco TE62074 from Digikey was the actual transformer used by most), which would give a DC voltage of ~24Vdc at the first test point and ~18VAC at the second, feeding the OPA548s. 24V is alot to burn up across an LM317/337 regulator and no need to waste that much energy. Not to mention the size of heatsink you would need on them 
	

	
	
		
		

		
		
	


	




 An amb labs sigma22 would make a very nice PSU for this as well.


----------



## bidoux

Ok, anyway I wasn't planning to do this PSU, just because I never want to leave a question unasked...
	

	
	
		
		

		
			





 thanks for the answer.
 The Sigma22 is 100$ for this price I can as well use the PSU we see on Dan's website.
 I like Kvant's design, I think I'll go for it.


----------



## MisterX

Serial Power Regulator w/Servo PCB w/parts /A-13 - eBay (item 250396899066 end time May-26-09 00:34:39 PDT)

 Is a little better then a standard LM7815 + LM7915 power supply. 
 And it's already built and tested....


----------



## luvdunhill

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_Is a little better then a standard LM7815 + LM7915 power supply. 
 And it's already built and tested...._

 

and comes from an unscrupulous vendor to boot! Looks like Nelson Pass has finally gotten some of his designs off this vendors listings, but many more reverse engineered designs are still sold there.


----------



## MisterX

Vendor or manufacturer? 
 Every single one of Lite Audio's "designs" is stolen from somewhere, including this one, are you "blaming" the right person for that?


----------



## luvdunhill

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_Vendor or manufacturer? 
 Every single one of Lite Audio's "designs" is stolen from somewhere, including this one, are you "blaming" the right person for that?_

 

The reseller is 100% the one to blame.


----------



## jcx

if you carefully read the headwize article you will find Gilmore recommends higher Vsupply for higher Z cans - also some resistor changes are required to keep Q pwr dissapation in check

 if you have 250 Ohm 880's you should want more Vsupply if you're using the Dynalo single ended instead of bridged


----------



## bidoux

So should I have more Voltage ? Like how many ?
 I have a Wall wart lying around. It says, "*non-regulated single voltage, 12VDC 300mA AC-DC*", but with my multimeter, I measure something like 18V so I thought I could use it. Is it what I'm looking for?Can I plug it into the wall and add a power regulator like the one MisterX or Kvant suggested next ?


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_So should I have more Voltage ? Like how many ?_

 

*jcx* points to the fact that standard dynalo does not reach realistic SPL levels of some types of music when used with high impedance/lowish sensitivity headphones. You will have to figure out yourself whether it indeed is your case or not; it can be calculated from headphone parameters. See other posts by *jcx* containing "headroom" for more info, some of them are even dynalo specific. Let me just repeat that depending on how much you increase the rail voltage you will have to implement other tweaks (resistor changes etc.), otherwise you risk frying output transistors, opamp in the servo circuit and, if you go really wild, also input jfets. Judging by your other posts I am not sure it is a task for you at this point.

  Quote:


 I have a Wall wart lying around. It says, "*non-regulated single voltage, 12VDC 300mA AC-DC*", but with my multimeter, I measure something like 18V so I thought I could use it. Is it what I'm looking for?Can I plug it into the wall and add a power regulator like the one MisterX or Kvant suggested next ? 
 

No, this *DC* walwart is not any good here. The plan I posted earlier requires *AC* to work, it cannot make +V,0,-V from a DC source. You could split a DC source (search "rail splitter" and "virtual ground"), but for +15V,0,-15V you need 30VDC (if already regulated) or more (in the case further regulation is needed). However, I myself would not go the virtual ground route.

 The module posted by *MisterX* needs AC input with a center tap. You can easily modify the rectifier along the lines of my earlier post to remove the center tap requirement. Again, single DC is of no help here either.

 BTW, the fact that you measure 18V on your walwart when unloaded is no surprise. It will sag as soon as you connect a load, probably to those 12VDC in the case you draw 300mA from it.


----------



## bidoux

Yep, I think I'll leave the voltage as it is, too noob for it !
 So if I want to use either MisterX's module either your plan, What kind of wall wart should I be looking for ?


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_...your plan, What kind of wall wart should I be looking for ?_

 

For instance, part number MC150A050U/F at farnell.com. It is 15VAC at 500mA, a little higher current rating would be better.


----------



## bidoux

Ok, now I get it a bit better, AC stands for Alternative Current and DC is for direct current. Is this one any good ?
 But the plan you gave me doesn't seem to have a really good diode bridge, usually there are more 4 diodes, aren't they ? 
	

	
	
		
		

		
		
	


	




 But if it is sufficient i'll take it 
	

	
	
		
		

		
		
	


	




.


----------



## digger945

4 diodes will be sufficient.
The &sigma;22 Regulated Power Supply.
 ^There are kits for this PS at Glass Jar Audio : AMB Labs Kits


----------



## kvant

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_4 diodes will be sufficient._

 

Yeah, right... surely you know what circuit is talked about here...

  Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_Is this one any good ?_

 

In the intended application, it is almost equivalent to the one I linked. The increased voltage does not help anything much, only the regulators will run hotter, the current limitation is again 500mA. By the way, if you really live where your profile says you do, good luck with plugging this 18 VAC wallwart into power sockets you have around.

  Quote:


 But the plan you gave me doesn't seem to have a really good diode bridge... 
 

And intentionally so.

  Quote:


 ...usually there are more 4 diodes, aren't they ? 
 

Take a moment to notice that in my drawing, there are two wires going into the rectifier stage (two diodes) and *three* wires are coming out of it. This is essential to have -V, GND and +V terminals in the end. Now look at the picture you linked, two wires in and only two wires out. How do you plan to force this really good diode bridge into that circuit then? It is usually a good idea to understand a circuit first and only then suggest improvements.


----------



## bidoux

Quote:


  Originally Posted by *kvant* /img/forum/go_quote.gif 
_By the way, if you really live where your profile says you do, good luck with plugging this 18 VAC wallwart into power sockets you have around._

 

I noticed it, looks like an English plug or something else but I can manage to fit it in French power socket .

  Quote:


  Originally Posted by *kvant* /img/forum/go_quote.gif 
_Take a moment to notice that in my drawing, there are two wires going into the rectifier stage (two diodes) and *three* wires are coming out of it. This is essential to have -V, GND and +V terminals in the end. Now look at the picture you linked, two wires in and only two wires out. How do you plan to force this really good diode bridge into that circuit then? It is usually a good idea to understand a circuit first and only then suggest improvements._

 

So yours provides a ground, where the one I linked would need something like
 an op-amp or something else to have a ground.

 I have a last question about the L7915 and L7815. There are three pins on it. Does the central one goes to ground, and the two others can be used in no particular order ?

 I link here your image with pin configuration according to here 





 PS: *digger945*, I already said I don't want to use the Sigma22.


----------



## digger945

The reference was for the schematic for the input to the sigma22, to give an understanding about how to arrive with positive, ground and negative using 4 diodes. I understand completely that you can use just 2 diodes or 8 diodes if you want.

 bidoux, the 7815 and 7915 have different pinouts.

 kvant, it would probably cost him less for two more diodes than many times larger caps. I was only trying to help the guy out a little as it seemed he was online for quite a long time waiting for someone to answer him. I do see now that you were trying to explain the half wave rectifier to him and I was probably only confusing him. My bad.


----------



## bidoux

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_bidoux, the 7815 and 7915 have different pinouts.

 kvant, it would probably cost him less for two more diodes than many times larger caps. I was only trying to help the guy out a little as it seemed he was online for quite a long time waiting for someone to answer him._

 

I'm not *waiting *for anyone to answer me, but it is kind to do so. 
	

	
	
		
		

		
			




 You just seemed to be so out of the topic when you arrived...
 You are saying large caps costs a lot but they are like 3 or 4 € each it is not that much.

 PS: The PSU looks a bit like this one.


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_So yours provides a ground, where the one I linked would need something like an op-amp or something else to have a ground._

 

Yes. There are certainly more ways to get a dual rail DC power from a single AC supply. You can rectify the AC into a single DC and then split this into two halves and create virtual ground; *tangent* has a detailed description of this technique on his web site. I sketched an alternative approach where I do the splitting directly from AC - the connection is also known as voltage doubler.

  Quote:


 I have a last question about the L7915 and L7815. There are three pins on it... ground, and the two others can be used in no particular order ? 
 

No, the other two pins are not interchangeable.

  Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_PS: The PSU looks a bit like this one._

 

Not only do the two circuits look a bit alike, they are the same circuit. The Silicon Chip incarnation uses smaller caps as their target current draw is considerably lower than what you aim for. It is a nice picture with identification of pins etc... saves me some drawing. I also did a bit of googling and found yet another page with this power supply. These guys provide a pictorial explanation of the circuit functions. They also have PCBs for sale but I am not sure there is enough room on it for heatsinks you will need on the regulators.

  Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_to give an understanding about how to arrive with positive, ground and negative using 4 diodes...
 kvant, it would probably cost him less for two more diodes than many times larger caps._

 

Absolutely, there are better plans to get bipolar supply. The issue with them is that *bidoux* expressed strong preference not to work with high voltages - and AC walwarts do not seem to come with a center tap (and ready made dual rail DC walwarts are also very scarce).


----------



## digger945

I will do some more research.
 Perhaps a ATX computer power supply with a +/-12V DC out could be modified or used for parts.


----------



## bidoux

I think I hav enough info now, will buy parts soon. Thanks everybody


----------



## breizheau

Hi there,
 i have finished the DYnalo part and wondering about the input impedance of the dynalo. I need this value coze of my attenuator control volume.


----------



## Pars

The input goes into a JFET gate, so input impedance is very high. The pot value will be dominant.


----------



## breizheau

Thx Pars.
 i asked this question because i have to calculate the "load resistor" of my attenuator and the value of the resistor depends of the input impedance


----------



## bidoux

I've finished the Dynalo using the power supply we talked about earlier. So far I have some questions to ask:

 -When I don't plug any kind of source to the amp, the DC offset is something like 6V for both channels, when a source is plugged (zune) it goes down.
 -For the left channel it is always under 5mV so it is ok I think but for the right channel it is more 50mV.

 The BJT pnp and npn are well matched, I checked this a few times, I don't think the problem would come from there. I swithed the LEDs but it doesn't change anything.

 The DC offset from the Zune is a bit less than 10mV, the DC servo should take care of it 
	

	
	
		
		

		
		
	


	




.

 Is there anything less I should check before I plug my Headphones (DT880 250 ohm BTW).

 Thanks a lot.

 Edit: Didn't populate R65 and R66, don't use a pot yet and don't use the trimpot (I have 4 of them if it can fix my DC problem).
 Edit: Breizheau suggested to shortcut the input while doing DC offset measurement. This way I get 50mV for a channel and 30mV for the other (I switched and changed some things meanwhile to have the best matching I can).


----------



## justin w.

there needs to be a load on the input of the amp. do not let the source or your volume pot be the only load. get the dc offset below 30mV for the servo to take care of it. swapping LEDs will get you there


----------



## bidoux

Ok, so I have to solder 500K resistors to R65 or R66. The problem came from the LED, I didn't match them, have to buy some more now, thanks Justin.

 Does upgrading the PSU is worth it ? The only difference I see between GS-1 and Gilmore Lite is the PSU so I guess it should make a difference, but i'm skeptical about high end power supply. Can anyone share his experience ?


----------



## j2kei

i believe PSU could make a big differnece. got a chance to listen to a gilmore lite with hd580/hd600. the gilmore lite just ran out of a wallmart PSU thingy (i dont relaly understand). i feel that the gilmore lite synergies really well with the hd580/600 and has a good hold onto them, but in complicated passages you really feel that the gilmore lite just needs more power for a much stronger control


----------



## bidoux

Quote:


  Originally Posted by *kvant* /img/forum/go_quote.gif 
_



_

 

I have some heat issues with the regulators. Does anyone knows how to calculate the size of Headtsinks I need on these regulators ?


----------



## bidoux

Since the dynalo is passive ground, would an active ground make it sound better ?


----------



## FallenAngel

Has anybody been able to get a hold of Dan from djgardner lately? I've sent him 3 emails since July 25th with no reply.

 Or does somebody have some Dynalo boards around?

 Thanks


----------



## bidoux

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_Since the dynalo is passive ground, would an active ground make it sound better ?_

 

Sorry to up this, does anyone have a clue ?
 For the ultra-reg power supply, is a center taped transformer 48VAC as good as 2*24 VAC ?


----------



## Nisbeth

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_Sorry to up this, does anyone have a clue ?
 For the ultra-reg power supply, is a center taped transformer 48VAC as good as 2*24 VAC ?_

 

In short, yes. However, if I can choose between 2x24V and 48VCT I'll always choose the 2x24V because of the extra flexibility of a true dual secondary. It's not important in this application but still...

 /U.


----------



## bidoux

Quote:


  Originally Posted by *Nisbeth* /img/forum/go_quote.gif 
_In short, yes. However, if I can choose between 2x24V and 48VCT I'll always choose the 2x24V because of the extra flexibility of a true dual secondary. It's not important in this application but still...
 /U._

 

Thanks a lot for your answer ! Now I have another question: 
	

	
	
		
		

		
			




 What is the VA ? there is to informations for the transformer, the output voltage and the VA. What is the VA and how much will I need for the Dynalo ?
 Is this kind better than this one ? The first one is often used.


----------



## FallenAngel

First one is toroidal and is better for this purpose. 15VA is good for a Dynalo (well, 2x 15V, 500mA), if going with 24V transformers (which I really don't know why unless you're making something like a Sigma22), go with 25VA.


----------



## bidoux

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_First one is toroidal and is better for this purpose. 15VA is good for a Dynalo (well, 2x 15V, 500mA), if going with 24V transformers (which I really don't know why unless you're making something like a Sigma22), go with 25VA._

 

In the original article, the PSU is 36 V (Kevin Gilmore he
	

	
	
		
		

		
		
	


	




), I thought I could low it to 24V but if 2*15V works too (we are talking about the one with op-amp, right ?)

 Edit: about the op-amp used in the power-supply, would these two work ? TDA2040V and TDA2005. For reference, here are two datasheet of op-amp that work: OPA541 and OPA548. I only want to know if they will burn or not when used...
	

	
	
		
		

		
		
	


	



 Thanks everyone.


----------



## kvant

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_I have some heat issues with the regulators. Does anyone knows how to calculate the size of Headtsinks I need on these regulators ?_

 

I have noticed in the "pictures" thread that you run your regulators naked. They are quite rugged, but using them entirely without heatsinks is hardly optimal. How many volts do you drop across the regulators? Bolt to them at least small heatsinks, for instance something along the lines of what *tangent* shows on his TREAD.

 As for the power supply from the article on Headwize, I think it is not the best route you can go. Do some reading around, I believe I saw some complaints about stability somewhere.


----------



## bidoux

If there is actually too much heat, they are supposed to stop working without being damaged. But you are very right, I was thinking of getting them some heatsink.


----------



## FallenAngel

The "original" was 36V - that's 2x 18V.


----------



## Pars

Actually, the original was a Triad F-378P, which was shown on the headwize schematic as being dual 36VAC secondaries, but the datasheet shows dual 28VAC. 

 A 2x18Vac transformer is a good choice, and is what headamp used on the Gilmore V2s, etc. which used the std. Gilmore Dynamic OPA548 PSU.


----------



## steinchen

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_Has anybody been able to get a hold of Dan from djgardner lately? I've sent him 3 emails since July 25th with no reply.

 Or does somebody have some Dynalo boards around?

 Thanks_

 

I got a populated spare board, pm me if you are interested


----------



## Pars

Quote:


  Originally Posted by *steinchen* /img/forum/go_quote.gif 
_I got a populated spare board, pm me if you are interested_

 

I had sent him an email a week or so ago and got a reply. He was in the middle of a move, but is settled in now and should reply. He does have all the stuff listed on his site still available.


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## bidoux

Are two PSU needed for a balanced dynalo ? I often see two power supply on Béta22 build but once, there was a balanced Beta22 with only one power supply so...


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## FallenAngel

Quote:


  Originally Posted by *steinchen* /img/forum/go_quote.gif 
_I got a populated spare board, pm me if you are interested_

 

Thanks for the offer, but I just finally got a reply from him a couple of days ago.

  Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_I had sent him an email a week or so ago and got a reply. He was in the middle of a move, but is settled in now and should reply. He does have all the stuff listed on his site still available._

 

Yep, he was moving, said he's now settling in and selling boards/parts again.

  Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_Are two PSU needed for a balanced dynalo ? I often see two power supply on Béta22 build but once, there was a balanced Beta22 with only one power supply so..._

 

The Dynalo does not draw nearly enough current to warrant separate power supplies, but if you want dual-mono balanced, why not.


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## bidoux

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_The Dynalo does not draw nearly enough current to warrant separate power supplies, but if you want dual-mono balanced, why not. 
	

	
	
		
		

		
		
	


	


_

 

price, as usual 
	

	
	
		
		

		
		
	


	



 Now, is a LM317 and LM337 better than an ultra-reg with kind of cheap op-amp instead of the OP548 ones (which are gonna cost 20€ each...)?


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## Pars

For the _n_-th time, just build a sigma22 and be done with it. Cheaper to build than the Gilmore supply and just as good. Glass Jar audio will ship you a kit.


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## bidoux

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_For the n-th time, just build a sigma22 and be done with it. Cheaper to build than the Gilmore supply and just as good. Glass Jar audio will ship you a kit._

 

Ok 
	

	
	
		
		

		
		
	


	




, I think I'll stop annoying everybody with this !


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## breizheau

Hi there !
 just a question : what about 20V as PSU ?


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## Pars

Quote:


  Originally Posted by *breizheau* /img/forum/go_quote.gif 
_Hi there !
 just a question : what about 20V as PSU ?_

 

I can't think of any reason offhad why +/-20V supplies wouldn't work fine. Make sure the opamps for the DC servos can handle that voltage. Also use a minimum of 25V caps for any electrolytics; I would probably use 35V just for margin. The original Gilmore Dynamic from the headwize article used +/-16.4V supplies, BTW.


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## bidoux

Breizheau has some cool project, he wants to mix the "up" a preamp with super simmetry (susy) from Nelson Pass and a Dynalo. If you upgrade the PSU to 20V, change the resistors in the CCS (explained in original article) and maybe parallel more output Z.
 I hope you don't mind if I put the schematic here: http://psykok.homelinux.org/diy/Calins/HUGS.pdf


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## Pars

Ah,yes, the CCS. I already use 620 ohm paralleled with a 10K trimpot on mine so would be close to being OK without doing anything. I'd increase them to 680 ohm just to be safe.


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## luvdunhill

Quote:


  Originally Posted by *bidoux* /img/forum/go_quote.gif 
_Breizheau has some cool project, he wants to mix the "up" a preamp with super simmetry (susy) from Nelson Pass and a Dynalo. If you upgrade the PSU to 20V, change the resistors in the CCS (explained in original article) and maybe parallel more output Z.
 I hope you don't mind if I put the schematic here: http://psykok.homelinux.org/diy/Calins/HUGS.pdf_

 

yup, the UGS (it's not called the "up") circuit can be used as a headphone amp, it's pretty straightforward. I wouldn't call it a mix at all...


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## breizheau

Hi there. First of all, i would like to show you my finished "Dynalo".


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## breizheau

As said, i have another project : HUGS (stands for "Headphones UGS").
 The UGS is based on Susy, patented by Nelson PASS. My preamp is really great and i thought about a mix with the output stage of the Dynalo.

 The prototype is already done, works pretty good and just waiting for a nice enclosure. The 1st one will be a wooden box. When the PCB will be done, i'll think about a real casing.
 It's a balanced output amp. The input could be balanced or not, the output will be always balanced. 
	

	
	
		
		

		
		
	


	



 Here the schematic : http://psykok.homelinux.org/diy/Calins/HUGS.pdf

 But i'll let you know. Stay tuned.


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## Pars

Very nice! What is the center PCB? Relay-based attenuator?


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## breizheau

Thx Pars. 
	

	
	
		
		

		
		
	


	




 Yes, it's a relay based attenuator bought at Dantimax in Denmark, 10Klog.
 I bought the same one but balanced and 50Klog for the "Bijou".


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## the_equalizer

Are chinese vendors in ebay a reliable source for the Dynalo FETs?

 Also, I'd like to buy a rev. C board. I sent an e-mail to djgardner some three months ago about this but I haven't received any reply. Does anyone have boards available?

 Thanks


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## Pars

Which FETs? the duals (2sj109/2sk389)? If so, no. If you are planning on using singles (2SJ74/2SK170) then maybe.

 Dan can be challenging to get a hold of. You could try putting a WTB ad in the for sale section here and see if you scare anything up.


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## weibby

If PCB is so hard to get, is there any equivalent?
 I'm interested in dynamic amp after building a Cmoy with an Opa2227.

 Now my DIY addiction withdrawal is full blown, itchy to try something like this.


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## the_equalizer

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Which FETs? the duals (2sj109/2sk389)? If so, no. If you are planning on using singles (2SJ74/2SK170) then maybe._

 

Sorry, I only put the FET numbers in the thread title... 
	

	
	
		
		

		
		
	


	



 yes indeed, I found several e-bay vendors offering (even matched) sets of 2SJ74/2SK170 FETs.

  Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Dan can be challenging to get a hold of. You could try putting a WTB ad in the for sale section here and see if you scare anything up._

 

Thanks for the advice. Will do.

 One more question, even though I am able to get 2SC1815 transistors where I live, I can only get hold of 2SA1015*GR* for the complimentary pair. Does anyone have any experience with those in the Dynalo? Would matching those GR to the non-GR work ?


 cheers!


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## Pars

Sorry, didn't notice your post title.

 As for the sc1815/sa1015, matching within grades, might work, might no:
 hFE (1) classification O: 70~140, Y: 120~240, GR: 200~400

 I personally have not had good luck going between grades for matching (not necessarily these devices). I just noticed that Mouser sells these (Fairchild version 512-KSA1015GRBU and 757-2SC1815GRTE2FT, for example), as well as bdent.

 EDIT: also, the Rev. B boards are virtually identical to the Rev. C, so I personally would not restrict your search to Rev. C only.


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## the_equalizer

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Sorry, didn't notice your post title.

 As for the sc1815/sa1015, matching within grades, might work, might no:
 hFE (1) classification O: 70~140, Y: 120~240, GR: 200~400

 I personally have not had good luck going between grades for matching (not necessarily these devices). I just noticed that Mouser sells these (Fairchild version 512-KSA1015GRBU and 757-2SC1815GRTE2FT, for example), as well as bdent.

 EDIT: also, the Rev. B boards are virtually identical to the Rev. C, so I personally would not restrict your search to Rev. C only._

 

Thanks for both pieces of advice. Wish me luck hunting parts for my Dynalo!


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## FallenAngel

I should have enough 2SC1815/2SA1015 in the parts bins to populate a board, you can have for free, and they're already grouped by hFE (well, most are O and some are GR), PM me your address and I'll drop them in the mail.


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## the_equalizer

Quote:


  Originally Posted by *FallenAngel* /img/forum/go_quote.gif 
_I should have enough 2SC1815/2SA1015 in the parts bins to populate a board, you can have for free, and they're already grouped by hFE (well, most are O and some are GR), PM me your address and I'll drop them in the mail._

 

Oh my... thank you *so* very much!


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## breizheau

I replied Oscar and i have to check the 2SA & 2Sc


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## Bizzel

Apologies for resurrecting this thread but I felt this was the most appropriate place to ask, rather than starting a whole new thread for one question.
   
  I'll be using a Sigma22 power supply for a balanced dynalo build and I wondered how this affects the choice of toroidal transformer to use. The AMB site has a nice table that shows VA ratings but only when used with beta boards and I imagine they draw a fair bit more power.
   

 Number of B22 Channels Recommended Transformer Rating 2 50VA 3 80VA 4 100VA
   
  Could I get away with 80VA or even 50VA with 4 dynalo channels (2 boards)?
   
*Edit: With some further searching I found an earlier post from amb recommending a 50VA 2x 18v toroid. Hope that helps anyone else in my position.*


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## bidoux

"Current consumption for the Dynalo if I remember right is around 100mA per channel" from Pars here

  So four channels is 400mA. If you power the sigma22 with 2*18VAC input it should be P=36*2^0.5*0.400=21W or 21VA. 25VA should be too low (transformers heats up). Now, I'm not sure about the consumption of the Sigma22.


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## bada bing

I've built a couple 2 channel dynalos powered by S22s with 35va xformers.
  The transformers have no problem at all and I set my amp bias on the high side.
  Most likely, you'll want to be on the low side with your bias because of the additional
  heat. The dynalo outputs get pretty hot for little TO92 devices.
   
  I believe that when set with specified bias, with all but the lowest impedance phones,
  the +-16.4v runs out of voltage (clips) before it falls out of class A.  If you're happy with
  the heat and power when unloaded, it shouldn't draw any additional current or get any
  hotter under normal loads.
   
  Yours should make a very nice amp. I like the dynalo and S22 combo a lot.
   
  I was surfing around the headwise library a few months ago and got interested in the
  balanced bridged output option KG wrote up in the original project. 
  The dynalo topology has the inverted differential signal created at the input fets but not used. By adding 
  2 output channels, it can run either balanced or SE output off a SE input. A servo centered, balanced
  output from a SE source and a 2 deck pot. Very cool. Very little cost for the addition. just output
  transistors-n-glue and a PSU big enough to drive them. I wonder why there hasn't
  been more interest in the addition ? Has anyone played around with this ?  I haven't found much
  discussion of it.
   
  I've been slowly cleaning up some board files for an add-on board
  with the two additional output channels.  Maybe this winter I can get it done.


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## Bizzel

I didn't know that, thanks for the info!
  
  Quote: 





bada bing said:


> The dynalo topology has the inverted differential signal created at the input fets but not used. By adding
> 2 output channels, it can run either balanced or SE output off a SE input. A servo centered, balanced
> output from a SE source and a 2 deck pot. Very cool.


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## Pars

Quote: 





bidoux said:


> "Current consumption for the Dynalo if I remember right is around 100mA per channel" from Pars here
> 
> So four channels is 400mA. If you power the sigma22 with 2*18VAC input it should be P=36*2^0.5*0.400=21W or 21VA. 25VA should be too low (transformers heats up). Now, I'm not sure about the consumption of the Sigma22.


 
  Actually, I was corrected by Dan Gardner in that thread that it is more like 150mA per channel. I would probably use 80VA myself, but that is overkill. 50VA would be fine. As a point of reference, the transformer used in the headamp gilmore v2 was an amveco TE62074, which is 35VA.


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## FallenAngel

I don't get it, 150mA/channel, 600mA for full amp, 2x 18V secondaries, so 36V * 0.6A = 21.6VA.  35VA transformer should be fine with enough overhead.


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## bidoux

Sorry for that. 150mA it is.


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## Bizzel

What's the disadvantage in over-provisioning - if I have a 50VA toroid and I'm using, say, 25VA will that generate more heat than if I had a 35VA transformer?


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## Pars

^ I don't believe so. The transformer will not regulate as well being more lightly loaded. The raw AC output will be a bit higher because of this.The power draw from the transformer is dependent upon the amp/PSU draw, so it won't go up simply because it is available. Larger transformers will tend to be noisier, but probably not enough (within reason) to worry about. 500VA, then you could probably worry.
   
  I'm not sure that the previous power calculations are correct. 150mA x 2 channels will be 300mA, not 600 (unless the calculation was for balanced, i.e. 4 channels). The draw is rail to rail, not each V+/V- rail to ground.


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## Bizzel

Thanks for the info. This is a balanced build so 600mA sounds like it's in the right ballpark. I'll probably end up getting the 50VA toroid since the price difference is pretty small.


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## Bizzel

Well the build is going very nicely so far. Apparently I haven't lost all my soldering skills which is a relief! 
	

	
	
		
		

		
			




   
  I have a query about the gain resistors if anyone's in the know about that: I want a gain of 6 so I bought 10K and 2K resistors which I fitted to locations R16, R46 and R7, R37 respectively. Is this correct?


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## Ferrari

Quote: 





bizzel said:


> I have a query about the gain resistors if anyone's in the know about that: I want a gain of 6 so I bought 10K and 2K resistors which I fitted to locations R16, R46 and R7, R37 respectively. Is this correct?


 

 Yes, R16 = R46 = 10K and R7 = R37 = 2K.


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## Bizzel

I'm trying to calculate the value of the power LED resistor, R67 and just wanted to check my working here.
   
  The LEDs I'm using are these white models (889-LW500AM) from Mouser - *vF of 3.3 and 20mA current draw*. Source voltage is 15.4v. I used this calculator to derive the resistor value and rating and I get *680ohm, 0.5 watts*. I notice the very first post in this thread suggests 4K for R67 so I find this result strange (if logical).


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## nikongod

20mA is the MAXIMUM rated current. 
   
  A 4Kohm resistor gets you 
  I=V/R
  I=(15.4V-3.3V)/4000ohms=0.003A=3mA
   
  I would try the LED at low current before you go testing the maximum rated current  Many people find that low-power LED's at fairly low current are plenty bright for indicator lamps.


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## 00940

Actually, for those leds, 100ma is the maximum current and 20ma the working current for the rated luminous intensity. see: http://www.optoga.se/pdf/LW500AM.pdf
   
  Honnestly, you picked weird leds. As indicators, led rated for 3-5ma working current are bright enough. You might try them at 5ma and see if it's bright enough.


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## nikongod

My bad.


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## Avro_Arrow

Can some one (any one...) look over my Dynalo Schematic to see
  if I made any errors? I've checked it over but another set of eyes
  is always helpful.
   
  Thanks!


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## Avro_Arrow

I already found one...it should be Kevin Gilmore, not David Gilmor...


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## 00940

No errors, more like questions:
   
  - why such a big cap (33uf) for the servo integration ?
  - why diodes in serie with r19 ?
  - why do you feel the need for a compensation cap with a gain of 10 ?


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## Avro_Arrow

1: It's hard to see in the drawing but it's .33, not 33. I guess I should write it 0.33uF.
  2: It's in the Dynalo Rev. C schematic.
  3: It's in the Dynalo Rev. C schematic.
  
  Quote: 





00940 said:


> No errors, more like questions:
> 
> - why such a big cap (33uf) for the servo integration ?
> - why diodes in serie with r19 ?
> - why do you feel the need for a compensation cap with a gain of 10 ?


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## Avro_Arrow

Here, the caps are better labeled.


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## bada bing

A couple observations.
   
  I've seen a touch of ringing on 100kHz square waves without some compensation.
  About 5-10 pF for gain 11 increasing to 33pF at gain 2 quelled it nicely on a couple I've seen on a scope.
  The dynalo mint tin boards from the group buy 5 years ago seemed to ring a bit more than the full size Rev C boards.
  The rev C boards almost go overboard on film and 'lytic  rail caps everywhere, the mint tin boards had no rail caps at all.
   
  I've built rev C with and without the thermal tracking diodes, I saw no harm but no benefit to including them.
   
*00940* : You were involved with the mint tin board group buy from years ago ? Do you still have the board files ?
              I know the board files were posted and open source, but they are hard to find now.


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## Avro_Arrow

Has anyone built this with the j74/k170 or just
  the j109/k389?
   
  I was planning on using about 3 inches by 4 inches to draw my board.
  I guess that would make it a full sized build. Each channel will have
  it's own board.


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## 00940

Quote: 





			
				bada bing said:
			
		

> *00940* : You were involved with the mint tin board group buy from years ago ? Do you still have the board files ?
> I know the board files were posted and open source, but they are hard to find now.


 


 Sorry, I just searched my drive and couldn't find anything  :-/  I was quite a noob at that times though and was more involved with setting up a small forum for building support and parts finding. Subsonic did the work for the pcb.
   
  However, if my memory is good, the PCB was heavily inspired by that layout by Sijosae:
   

   
  Just stick two, one next to the other. Details here: http://www.headphoneamp.co.kr/bbs/zboard.php?id=diy_sijosae&page=2&sn1=&divpage=1&sn=off&ss=on&sc=on&keyword=gilmore&select_arrange=headnum&desc=asc&no=17


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## Pars

Quote: 





avro_arrow said:


> Can some one (any one...) look over my Dynalo Schematic to see
> if I made any errors? I've checked it over but another set of eyes
> is always helpful.
> 
> Thanks!


 
   
  You seem to have the + rail and the feedback loop connected together/confused:


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## Avro_Arrow

Yes PArs, your right...I did that when I connected the Servo...ooopppssss 
	

	
	
		
		

		
			




  I'm sure I would have caught that myself the next time I looked at it...thanks!


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## nattonrice

Hehe it would have made for an interesting sound.


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## Avro_Arrow

I don't think it would have made an interesting sound for very
  long before the magic smoke would have decided it wanted to
  be somewhere else...
  
  Quote: 





nattonrice said:


> Hehe it would have made for an interesting sound.


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## Avro_Arrow

I think this one is finally correct.
  Please check it over for any net or value errors.
  Thanks everyone.


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## Bizzel

Could I ask for another pair of eyes on this PCB layout please? It's a 'backplane' for a Dynamid amp so it accomodates two Dynalo boards with headers for inputs, outputs and a stepped attenuator. I've made a 1:1 scale printout and checked that the sizing and hole alignment is correct for my chosen case but I'm just wondering if anything obvious stands out as being wrong.


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## ajuztam

Hi lads. Sorry for digging out an old thread. I'm building a dynalo at the moment and I want to use it as a headphone amp and a preamp. How can I get a RCA output from it that I can feed my amp with without hurting it. There will be a dac instaled with it in one case and I want to be able to feed my amp with a signal from dac going through dynalo amp. Is that possible? please advise me on what to do to achieve both Headphone out and RCA out.  Thanks in advance


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## luke99

I had some problems with my Dynalo, but its going great. I could bias the front end as the trimpots were causing probs. It has Salas shunts and a separate capacitance multiplier psu. Will try and take some pics.


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## ajuztam

Are your transistors soldered or they sit in sockets? I'm also building one but i'm not that far yet. I recommend swapping transistors from working side. Did you check all test points and compared them to given values?


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## luke99

Hi Ajuztam, all voltages are correct apart from the ones I have mentioned above. Transistors are all soldered, only the jfets use sockets and R11 and R14.
  
 Anyone else have any ideas?


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## luke99

Cap multiplier, the second is a Salas Shunt and Dynalo on top, third is my chaotic desk, I got so much hifi and I usually listen FM National Radio


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