# 'My' CMoy



## guzzler

I don't know if many people remember seeing my CMoy layout using the Panasonic EVJ and a TLE2426 railsplitter, but a fellow audiophile (not sure if he's here on Head-Fi) from the UK, Alan, has got round to building it. It came out better than I thought it would, and he's agreed to let me post the pictures for everyone to see. He used a photo-etching method, AFAIK, and produced excellent results with it. Anyway, enough waffling, pictures:

 Layout






 Etched board





 Completed





 Click here to download the layout in Eagle so you can etch one for yourself, should you so wish

 My thanks again to Alan, and hope you liked the shots from him

 g


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## Ishkabibel

You wouldn't have one of those PCBs around for sale would you? I might be able to create a working Cmoy with that rather than the protoboard disasters I've made...


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## jamont

That's a nice layout. I'd be interested if you wanted to sell some boards...


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## Tobrew

I've been planning to build one just like this and just might use your PCB. I notice that R4 and R5 are jumpered. Why? Also, what are the values on the other resistors? Does this follow the standard CMOY resistors? Thanks for the great post Guzzler.


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## skyskraper

wow. very cool!@!!


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## Nisbeth

Nice layout guzzler!. Could be useful to have a few of those boards lying about for "emergencies" 
	

	
	
		
		

		
		
	


	





 /U.


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## mustang

I'd be interested as well regarding the boards...


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## alexm

Quote:


  Originally Posted by *Tobrew* 
_I've been planning to build one just like this and just might use your PCB. I notice that R4 and R5 are jumpered. Why? Also, what are the values on the other resistors? Does this follow the standard CMOY resistors? Thanks for the great post Guzzler._

 

R5 is not required, they say it might be useful to tame low level hiss (I left it out in my cmoy).
 As for R4, I suppose it's for convenience: you could for example set up easily a switchable gain (Guzzler please correct me if I'm wrong 
	

	
	
		
		

		
		
	


	




 ).

 Let me say again (I did already in another thread) that minipcb is so kawaii (a cutie)...


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## guzzler

This is just the email I wrote to Alan regards the resistors, didn't really want to write it all again 
	

	
	
		
		

		
		
	


	




:

 The values from Right to Left (with the potentiometer on the right, and output to the left):

 1. 100K (R2 in Headwize article)
 2. 1K (R3 ... )
 3. 10K (R4 ...) change this one to alter gain
 4/5. See the note on reducing noise in the HeadWize libary. The one on the right is inside the feedback loop, and the left one is outside. You'll have
 to jumper them if you don't use either of them.

 regards boards, it wouldn't be hard to get some made up quite cheaply but it's an easy circuit to etch yourself; all the traces are quite wide and nothing is too close together. I wouldn't be able to do boards until the start of december due to restrictions on personal businesses at my university which I start in a week. Someone else could take on the boards if they would like to? My suggestions would be to include variable pitch on the input capacitors so you wouldn't have to find ones in that particular size, although it is a common size. If double sided wasn't any extra, there is space to put an LED current limiting resistor in as well, as opposed to the two spare power pads that are there at the moment.

 g


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## Tobrew

I've been wanting to build a Cmoy that uses a TLE2426 railsplitter so this seemed like a great place to start. I used the PCB design by guzzler and modified it slightly. I added a diode and an LED on the board. These two items make the powersupply section look like a MINT (my next project). I added the diode because in the Serpac case I used it is way to easy to reverse the battery polarity. I also put the LED on the board because the case is clear and I thought I would be a neat effect. I used ExpressPCB to redraw the board and then did the etching myself. Very easy. Thanks guzzler for giving me another project 
	

	
	
		
		

		
		
	


	




 . Anyway, here are the photos.


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## bpribadi

Excellent layout! Very neat and compact!


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## tkerby

Alright, how do you do those 3d pcb pictures?


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## guzzler

Quote:


  Originally Posted by *tkerby* 
_Alright, how do you do those 3d pcb pictures?_

 

 It's a plugin for Eagle called Eagle3D.

http://web2.callisto.twam.info/

 g


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## guzzler

Little embarassed, but I've made a mistake, as pointed by alexm. R4 isn't working as a hiss reducing resistor as I intended, but could be a switchable gain like alexm said. It still needs to be jumpered if you don't use it. My apologies for that, and I'll amend the PCB design 
	

	
	
		
		

		
		
	


	




 * slinks off with tail between legs *

 g


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## shw24

nice layout... , btw anybody know where to get the parts here in the UK? sorry for this silly question, coz this will be my first DIY...


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## tess

What parts are you after?
 They are the pictures of my amp, from which I used Guzzlers design.
 I can etch you a board if you want? you do the drilling.
 Resistors,caps are avilable from Maplin the op amp from RS and the pot is USA only i think, Digikey but you could just wire any pot to the board.

 Alan.


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## Bakke

Hi. Does it get much better with an Cmoy like this than without an amp? Can you tell exactly the parts you have used? How big caps and pot? Thanks.


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## guzzler

the EVJ you can't get here in the UK, I had a few a while ago but sold them all. I've still not corrected the layout, but might just leave it as it is as it might even be more useful than the internal hiss reducing resistor. The input caps are 7.5mm pitch, you could use 1uF Wima MKS-4s there. The electrolytics are 10mm diameter, 5mm pitch. Download the layout in Eagle and all the dimensions are listed in there. Rapid Electronics stock all the standard parts, opamp you could get from RS, but you'll have to source the TLE2426 and potentiometer from elsewhere

 g


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## Nisbeth

I'll probably be ordering from digikey within the next few weeks (no guarantees though). If anybody in Europe is interested in the EVJ's let me know by PM 
	

	
	
		
		

		
			






 /U.

 EDIT: Because of VAT etc. the price is going to be somewhat higher than what's listed on the digikey website


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## kloan

what's that little thing, close to the middle.. with 3 leads.. kinda like a 3/4 moon shape.. ive never seen that on a cmoy before..


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## commanderkeen

Quote:


  Originally Posted by *kloan* 
_what's that little thing, close to the middle.. with 3 leads.. kinda like a 3/4 moon shape.. ive never seen that on a cmoy before.._

 

That is the rail splitter. The part number is TLE2426


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## kloan

ah, ok.. cool thanks


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## MaxW

Mine is almost going


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## Kenny12

Quote:


  Originally Posted by *MaxW* 
_Mine is almost going 
	

	
	
		
		

		
		
	


	







_

 

ahahaha

 i don't see why go though all this trouble for a cmoy, money better spent in a mint / pimeta imo


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## MaxW

Quote:


  Originally Posted by *Kenny12* 
_ahahaha

 i don't see why go though all this trouble for a cmoy, money better spent in a mint / pimeta imo_

 

Already got a pimeta, what money? must cost about NZ$10 + opamp.
 I just liked the PCB, thats why I decided to make it


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## MaxW

Someone has asked for my editted version on the layout.
 The pot holes on the PCB are for a Taiwan Alpha pot from www.jaycar.co.nz.
 The wholes are 2.5 (h) and 2.3 (wide) spaced.


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## pabbi1

Anyone willing to part with a board?


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## kloan

I contacted a few companies to see how much it would cost to make these boards.. some ignored me, one quoted over $15 a piece (they can go to hell) and another one quoted approx $3 cdn each.. which I think is a good deal.. I haven't followed through with it though.. but if I sell a few amps I just might go for it.. if I do, I'll post a group buy for some and see if there's enough interest.. I'm really surprised no one else has done this yet.. it would be really nice to have a proper PCB for newbies and everyone else to make the cmoys since they're so popular...


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## Stephonovich

It's been done. That being said, I never got one, and would be quite happy for the chance to put my CMoy in a smaller case. Currently it's sitting in a rather giant Hammond case that would be much better served with a PIMETA or similar.

 And $2.50 USD a board? Heck, I'd be willing to pay you $10 for one. Just think of the profit you could make


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## guzzler

The place I get my boards printed at quotes about 3 euros for quantities of 25, which would obviously go down if more were done.

 g


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## pabbi1

Is this really much different than a MINT?


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## philodox

Quote:


  Originally Posted by *pabbi1* 
_Is this really much different than a MINT?_

 

I would think that a MINT would be quite a bit better, but cmoy's use cheaper parts as far as I can tell.


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## TwinkieTheKid

i've got the eagle3D plugin but where can i get Eagle?


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## MaxW

Quote:


  Originally Posted by *TwinkieTheKid* 
_i've got the eagle3D plugin but where can i get Eagle?_

 

http://www.cadsoft.de/cgi-bin/downlo...ub/program/4.1


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## MaxW

I have finished mine:












 I used 68 ohm resister as the last one on the end (R5) as the headwize article says 50-100 BUT I am getting 130mV DC on one channel and 1mV on the other with my 2x OPA627's. I tried an LM833 but that gave 390mV on both channels


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## Necroist

Looks great!

 If its not too much to ask, could you share your schematics? Would love to see them.


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## MaxW

Quote:


  Originally Posted by *Necroist* 
_Looks great!

 If its not too much to ask, could you share your schematics? Would love to see them._

 

Its not my design 
	

	
	
		
		

		
		
	


	



 The schematic is here:
http://headwize.com/projects/showfil...=cmoy2_prj.htm
 and the layout details are in the beginning of this thread


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## shw24

hmmm....looks good with OPA627, how does it sounds with OPA627 compare to other standard cmoy? and is it still far from the mint quality?


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## MaxW

Quote:


  Originally Posted by *shw24* 
_hmmm....looks good with OPA627, how does it sounds with OPA627 compare to other standard cmoy? and is it still far from the mint quality?_

 

See my comments here:
http://www6.head-fi.org/forums/showthread.php?p=1087501


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## james902

Quote:


  Originally Posted by *Tobrew* 
_I've been wanting to build a Cmoy that uses a TLE2426 railsplitter so this seemed like a great place to start. I used the PCB design by guzzler and modified it slightly. I added a diode and an LED on the board. These two items make the powersupply section look like a MINT (my next project). I added the diode because in the Serpac case I used it is way to easy to reverse the battery polarity. I also put the LED on the board because the case is clear and I thought I would be a neat effect. I used ExpressPCB to redraw the board and then did the etching myself. Very easy. Thanks guzzler for giving me another project 
	

	
	
		
		

		
		
	


	




 . Anyway, here are the photos._

 

you got PM'ed


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## JCYC5

Guys...

 I'm trying to use this circuit board for a school project...

 BUt I won't be able to find the rail splitter here... 

 Can anyone suggest how I can use Guzzler's PCB?

 Also, if I can't find a volume pot to use over here, how can I bridge the connections to still allow it to be operable?

 Thanks so much!!


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## MaxW

Quote:


  Originally Posted by *JCYC5* 
_BUt I won't be able to find the rail splitter here... 
 Can anyone suggest how I can use Guzzler's PCB?_

 

You can use 2 resisters instead of the rail splitter I think. Its in the original Chu moy schematic here:
http://headwize.com/projects/showfil...=cmoy2_prj.htm

 but I get a "Bandwidth Limit Exceeded" error message at the moment.


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## Edwood

If you guys are going to go for professionally made PCB's, the layout could be compressed more to make it even smaller.

 As it stands, it's not much smaller than the Mint. But when the Mint is cut in half, the CMoy loses sizewize. Perhaps a smaller one based on Tangent's Micro Cmoy?

 But a Mint is significantly more expensive parts wise.

 -Ed


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## guzzler

Ed, you're right, it can be made smaller, but that's not really the primary objective of this design. It's done to be very easy to make for anyone, regardless of experience, and to avoid tombstoning resistors, and having resistors with flying leads. Also, there's no SMD work to do (I've got a version that's the sort of "maxed out" brother of this, to use with LM6172 that includes more on the same board. If you want a small board with more on, go with the MINT...

 g


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## Pars

Quote:


  Originally Posted by *guzzler* 
_Ed, you're right, it can be made smaller, but that's not really the primary objective of this design. It's done to be very easy to make for anyone, regardless of experience, and to avoid tombstoning resistors, and having resistors with flying leads. Also, there's no SMD work to do (I've got a version that's the sort of "maxed out" brother of this, to use with LM6172 that includes more on the same board. If you want a small board with more on, go with the MINT...

 g_

 

I'd like to see that one, if you don't mind sharing (the LM6172 one). On another note, since you were so kind as to post the original CMoy layout, I took the liberty of converting it into an A47, with the Pana pot, which I can post if anyone wants it, and of course, if its OK with you Guzzler.

 Chris


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## guzzler

Sure, here it is. Double sided I'm afraid:






The ground plane avoids the input pins to reduce stray capacitance
You can see the 0805 decoupling caps (rail-to-rail, and rail-to-ground)
Compensation capacitors parallel to R4
Provision to use resistors for the railsplitter instead of the TLE
Added space for 3mm LED + 1/8W resistor
Fixed that stupid mistake in the layout....
Made component names consistent with the original article


 Please note, this board has never been tried out, so I don't guarentee anything!

 Sure, post the A47; I never got round to doing one of those layouts properly (some half arsed efforts though)


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## Nisbeth

Neat layout Gus 
	

	
	
		
		

		
		
	


	




 If anyone runs off and has these manufactured, I'd most likely be interested in buying a couple. They could be very useful to have around 
	

	
	
		
		

		
		
	


	





 /U.


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## skyskraper

chris, id be interested to see the a47 layout, the sgheadphones guys have done an a47 layout, would be keen to see the differences in how the two have been laid out....


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## Earwax

Quote:


  Originally Posted by *Nisbeth* 
_Neat layout Gus 
	

	
	
		
		

		
		
	


	




 If anyone runs off and has these manufactured, I'd most likely be interested in buying a couple. They could be very useful to have around 
	

	
	
		
		

		
		
	


	





 /U._

 


 Me too. That's a very nice little layout.


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## tess

I’m at the moment having some professional boards made up from Guzzlers original design, (with his agreement). Its slightly larger, but has the provision for either a rail-splitter or resistors, also I have included the LED resistor on the board design.
 It has also been altered for the use of an ALPS RK097 pot instead of the Panasonic, ideal if you don’t live in the USA.
 Its ideal for a first time build, and will still fit an Altoids tin.

 Alan.


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## Pars

Quote:


  Originally Posted by *skyskraper* 
_chris, id be interested to see the a47 layout, the sgheadphones guys have done an a47 layout, would be keen to see the differences in how the two have been laid out...._

 

Well, I really just added a second socket and the traces to guzzler's layout, but here is the board file in Eagle.


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## guzzler

Folks, I've had some long conversations with Tess about the CMoy board, and we agreed that due to my lack of time, and the fact my board has some SMD and component choices, his board was the better option just now especially as it was aimed at the beginner category. This doesn't preclude getting some of the double-sided boards made up, but it certainly won't be for months...

 g


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## JCYC5

One more question on this....

 Which resister am I supposed to jumper across? Tangent's schematics says it's R5, but the picture someone posted (the render) showed it to be R4...


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## Anthrax

which part is IC2 on that A47 layout, also how do i know which resistors ?


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## Pars

IC2 is another opamp (same as IC1). OPA2132/34. whatever you would use in a CMoy. Note that there is no provision for additional PS decoupling that would be necessary if you wanted to use one of the really cranky opamps, like an LM6172 for example).

 In an A47, what had been R5 in Tangent's design (now R4 in this layout) is necessary, and is 47 ohms, as is R5. This is where the "47" part of the A47 comes from.

 Basically, Tangent's resistor numbers are one higher than the ones here, so his R2 would correspond to R1, etc.


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## tess

Have eventually got around to posting pictures of the boards I had made from Guzzlers original design.
 It has been altered with the help of Digi01 and myself to use the non-switched Alps RK097 pot which is much easier to get in the UK (RS Components) the Panasonic EVJ-C20 is just unobtainable here.
 Also I have added the LED resistor and LED pad on the board.
 Its fitted with TLE rail-splitter (can use resistors instead) Nichicon UPW 330uf caps and Vishay MBB resistors and a opa2227 op-amp with a Purple LED.
 Ended up just the right size to use a battery holder, so no more battery loose in the tin.

 Thanks again Guzzler.


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## star1

I was wondering if you have any spare boards for sale?

 I mite get a working amp..... I hate stripboard


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## jasonhanjk

Quote:


  Originally Posted by *skyskraper* 
_chris, id be interested to see the a47 layout, the sgheadphones guys have done an a47 layout, would be keen to see the differences in how the two have been laid out...._

 


 You meant his one?


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## angelcorbin

Hello everyone this is my first post to the forum I have been looking at this thread and downloaded the eagle board layout from guzzler and decided to redo it in protel if I can get anyone to have a look at the layout to see if it looks ok I double checked it but it's allways best to get other opinons before you jump in and make a board. I have attached a pic and the pcb file.
 Thanks
 AC

 P.S. Sorry about the picture I attached the quality of it was terible I will paste a link to a better pic of it below
 Thanks

http://people.aapt.net.au/grannygroover/Cmoy.jpg


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## digi01

well done tess!I am very happy with you UK diyer.thanks Guzzlers,your upCMOY idea are smart 
	

	
	
		
		

		
		
	


	




 For the tess version,there are 5 modify basis on Guzzlers original design.
 1,Alps RK097 & Panasonic EVJ-C20 footprint available
 2,LED resistor and LED available
 3,PCB stand-off holes available,3mm diameter.the unit is easy to be set up in a CDP.
 4,TO-92 packaged TLE2426 rail-splitter & standard resistors rail-splitter footprint available
 5,double ground mounting pads available,you could use RA-1 liked power supply.

 some more ideas for future edition.
 1,dual channel design
 2,CMOY/A47 footprint available
 3,more rooms for big FC caps
 4,...etc

 I have made a rough breadboard version,FYI below.
PIC 
 I use PDIP packaged TLE2426 for rail-splitter.

 thanks
 Zang


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## angelcorbin

Hi everyone here is the link for the updated version let me know if I have done anything wrong please.
 Thanks
 AC
http://people.aapt.net.au/grannygroover/Cmoy%20V2.jpg


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