# Strip Board CMOY Revisited



## Fred_fred2004

I was asked a while ago about making a stripboard CMOY, I was bored and hung over (red wine!!) so decided to remake it again, I hope its some use to anyone getting their feet wet.

 here it is







 And this is how to make it
 first a piece of strip board




 Mark where to cut the tracks




 Use a pices of wire to transfer the cuts from top of the board to the bottom




 Cut the tracks I use a drill bit




 Fill her up!!!!













 Connect the pot and sockets









 Output socket to the board





 Pot and input socket to board





 BAttery LED & Switch





 Run power to the chip





 Amazing how something so simple sounds so good





 I wish I'd thought of it!!!!!!!

 Cheers
 FRED


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## nihraguk

Thanks Fred, this will be very helpful in my attempts to troubleshoot my stillborn cmoy-on-a-stripboard.


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## Dan55

Same here. Thanks a lot, Fred. And thanks to the wine!


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## Fred_fred2004

Thank goodness for Asprin


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## the search never ends

Hey Fred, do your amps work best on 1.5 alkaline, or do the 1.2 nimh do just as well?


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## Fred_fred2004

The amps dont really care where the power comes from as long as there is enough of it 
	

	
	
		
		

		
		
	


	



 Which amps are you talking about??


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## the search never ends

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_The amps dont really care where the power comes from as long as there is enough of it 
	

	
	
		
		

		
		
	


	



 Which amps are you talking about??_

 

Thanks Fred


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## fordgtlover

Nice job Fred_fred2004


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## Billy213

Very nice Fred. My connections on the pot seem to be done differently to yours, I'll grab a few pictures when I get a chance. Wish I put some shrink wrap on too. 
	

	
	
		
		

		
		
	


	




 Stuck on a forklift course this week so there's not much I can get done. =/


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## Fred_fred2004

Mate its not true audiophile without cryo treated shrink wrap and of course you need to choose the colour I'm sure black gives the warmest sound, 

 The audiophile gods will strike me down for that!!!! but it was worth it


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## mrtndoog

Are you serious does heatshrink really matter ?


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## FallenAngel

If you believe it does, the price of that placebo would likely be the best value upgrade ever!


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## Fred_fred2004

You're just not open to new ideas  
 I cryo treated the stripboard (left it in the freezer) and the sound was as good as a B22........honest.......


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## Dan55

Quote:


  Originally Posted by *mrtndoog* /img/forum/go_quote.gif 
_Are you serious does heatshrink really matter ?_

 

I've been reading through a bunch of threads trying to figure out this whole amplifier thing and have noticed a bit of sarcasm in one or two of Fred's posts. 
	

	
	
		
		

		
		
	


	




 (From my very limited experience, heat shrink can be helpful in preventing shorts if you're using a metal case)


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## scompton

Quote:


  Originally Posted by *Dan55* /img/forum/go_quote.gif 
_I've been reading through a bunch of threads trying to figure out this whole amplifier thing and have noticed a bit of sarcasm in one or two of Fred's posts. 
	

	
	
		
		

		
		
	


	




 (From my very limited experience, heat shrink can be helpful in preventing shorts if you're using a metal case)_

 

Or anywhere bare wires or leads can touch each other.


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## Fred_fred2004

OK maybe a trace of sarcasm 
	

	
	
		
		

		
			





 just having a bit of fun

 the thruth is freezing the strip board in the freezer made no difference - and I had such high hopes 
	

	
	
		
		

		
		
	


	




 Oh well back to fitting a B22 into an Altoids tin

 cheers
 FRED


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## scompton

I assume you've seen oneplustwo's B22 in a cookie tin

bonnie & jason » Beta 22 amplifier build


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## Fred_fred2004

Yes it was brilliant, nice to see an amp that cost more than the case


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## Billy213

Fred would you be able to do me a diagram to show how I would connect up my 6 pin 1/4 headphone output jack? I'm really struggling to find out how it should be connected.

http://www.maplin.co.uk/Module.aspx?ModuleNo=982

 That's what I have. The rest of my layout matches yours. I hope I've got my pot wiring right, only time will tell.


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## Fred_fred2004

Hi Billy

 Gnd goes to gnd
 ring is right goes to pin 7 of the chip
 Tip is left goes to pin 1 of the chip

 ignore the other three pins they are switchable

 cheers
 FRED


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## igotyofire

Quote:


  Originally Posted by *Billy213* /img/forum/go_quote.gif 
_Fred would you be able to do me a diagram to show how I would connect up my 6 pin 1/4 headphone output jack? I'm really struggling to find out how it should be connected.

1/4â€ Stereo Socket with Chrome Bezel : 6.35mm (1/4 Inch) Stereo Jacks : Maplin

 That's what I have. The rest of my layout matches yours. I hope I've got my pot wiring right, only time will tell. _

 


 i really like how tanget recommends toning them, then any plug u ecounter will be easy.....just plug up a male to male interconnect cable to jack. in yourcase an adapter to the 3.5mm might make things easier, since ive never seen a 1/4 male to male....anywho then touch the different parts of the male tip....ground,right chanel, left channel(right) with a multi-meter to the tips of the jack connection to figure out which goes where in your circuit.


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## mrtndoog

Fred, can I get all the parts from Jaycars so I can try this over the Christmas break, I' haveing a little crisis deciding what I need
 thanks


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## Fred_fred2004

Jaycars are fine they don't have pots with switches so seperate pot and switch


 CAT. NO. ZL3972 OPA2134 opamp (its all they have)
 CAT. NO. RP8756 10K Log double gange pot
 CAT. NO. RM7165 0.47uF 100V MKT capacitor (2)
 CAT. NO. PS0132 3.5mm skt (2) better for air wireing
 CAT. NO. RE6314 470uF low esr 16Volt (2)
 CAT. NO. PH9233 battery clip
 CAT. NO. ZD0150 red led
 CAT. NO. ST0335 toggle switch
 CAT. NO. PI6452 8pin IC socket



 metal film resistors 1/2watt

 10K (2)
 1K (2)
 100k (2)
 4.7K (2)
 6.8K for led

 chunk of strip board and some solder (60/40)


 Hope that helps
 cheers
 FRED


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## Billy213

Fred I've completed mine but it's not working properly. I've got sound from the right channel and a very faint sound from the left. It also distorts when I turn up the volume. Any ideas?


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## Fred_fred2004

Yes its broken 
	

	
	
		
		

		
		
	


	







 Sorry couldn't resist 
	

	
	
		
		

		
		
	


	




 The circuit works so you've proberbly made a simple mistake its easy to do, any chance of a picture or two

 cheers
 FRED


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## Billy213

Yeah I'll upload a couple when I get home from work tonight. Gonna 'borrow' their soldering iron for a while as well. A rather hot 120W 110v one, works rather nicely. 

 Only problem with mine is the wire I've used, can get in the way a bit.. Oh, and it doesnt have an on/off switch.


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## Billy213




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## Fred_fred2004

Get a old toothbrush or similar, dip it in meths and scrube the bottom of the board blot it up with a tissue. then have a good look for shorts between the traces


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## Fred_fred2004

Just thought , how is the input connected to the pot, its hidden in the pics


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## diff_lock2

I spent some time working on a strip board cmoy, the input caps are off the board and it uses some TLE chip for rail splitting (tangentsoft). You can really make a compact cmoy with stripboard.


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## lasereyes

i have a few questions. What is a 100kk resistor?
 what does p1 and p2 represent? How do I wire a potentiometer correctly?


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## scompton

Quote:


  Originally Posted by *lasereyes* /img/forum/go_quote.gif 
_i have a few questions. What is a 100kk resistor?
 what does p1 and p2 represent? How do I wire a potentiometer correctly?_

 

A 100K resistor has a resistance of 100 KOhms.

 p1 and p2 are the 2 channels of the potentiometer (volume control)

 I suggest you read here

How to Build the CMoy Pocket Amplifier


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## lasereyes

I think i understand now

 but the resistor is labeled 100kk, does this mean megaohms? or was it a typo?


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## Fred_fred2004

It was a typo


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## lasereyes

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_It was a typo 
	

	
	
		
		

		
		
	


	


_

 


 ha ha thanks for clarifying!


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## lasereyes

can sombody take a look at this cart at mousers

http://www.mouser.com/ProjectManager...sID=062c226da0 

 and tell me if I got everything right?

 also, what kind of potentiometer is correct? i couldnt find any with both channels.


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## Fred_fred2004

The electrolytics pick a higher voltage 16volts would be better
 film caps use 0.47uF
 the resistors you can use 1/4 watt for all of them

 do you have - jacks, LED (and resistor), battery clip, switch

 The pot - 10K dual ganged, LOG 

 cheers
 FRED


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## lasereyes

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_The electrolytics pick a higher voltage 16volts would be better
 film caps use 0.47uF
 the resistors you can use 1/4 watt for all of them

 do you have - jacks, LED (and resistor), battery clip, switch

 The pot - 10K dual ganged, LOG 

 cheers
 FRED_

 

Thanks! by the way, are mini jacks adequate? that's what my head phones use. im still confused though the film capacitors say .1 micro farad on your diagram?


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## Fred_fred2004

The 0.1uf cap is the "traditional" value and I used it to maintain the similarity to the original cmoy, but a higher value will improve the bass response and the 0.47uF is a easily optained replacement. The mini jacks are fine make sure they are stereo and not mono
 cheers
 FRED


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## lasereyes

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_The 0.1uf cap is the "traditional" value and I used it to maintain the similarity to the original cmoy, but a higher value will improve the bass response and the 0.47uF is a easily optained replacement. The mini jacks are fine make sure they are stereo and not mono
 cheers
 FRED_

 

cool thanks! and are the led resistors the ones already in the schematic or are they wired directly to the led?


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## Fred_fred2004

Just use a value between say 4.7K and 10K and wire directly to the LED it just depends how bright you want it to be, in the pictures the resistor is under the heatshrink protecting the led connections
 cheers
 FRED


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## lasereyes

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_Just use a value between say 4.7K and 10K and wire directly to the LED it just depends how bright you want it to be, in the pictures the resistor is under the heatshrink protecting the led connections
 cheers
 FRED_

 

if i use a super-bright 4.5 volt led do i need a resistor?


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## Fred_fred2004

yes you'll be using 9 volts , do you want a torch or an amp 

 cheers
 FRED


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## lasereyes

Quote:


  Originally Posted by *Fred_fred2004* /img/forum/go_quote.gif 
_yes you'll be using 9 volts , do you want a torch or an amp 

 cheers
 FRED_

 

ha ha thanks. 4.7k it is then. Oh and, where the heck are dip-8 sockets at mousers? cant seem to find them.


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## Fred_fred2004

look for IC sockets they should be around there

 cheers
 FRED


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## lasereyes

I have another question. Which electronics store is the best to purchase these components


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## Fred_fred2004

Sorry I'm not much help, I'm in Australia


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## scompton

Tangent's site lists specific part numbers for Mouser, Digikey, and Radio Shack. I usually order from Mouser. If they don't have the part, where ever I can find it. You can probably find most of the parts at Radio Shack if you want to go local. All of this assumes your in the US.


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## lasereyes

Quote:


  Originally Posted by *scompton* /img/forum/go_quote.gif 
_Tangent's site lists specific part numbers for Mouser, Digikey, and Radio Shack. I usually order from Mouser. If they don't have the part, where ever I can find it. You can probably find most of the parts at Radio Shack if you want to go local. All of this assumes your in the US._

 


 yeah i took a look at all of these sites and finaly decided to order from newark because they seem to have the best prices. I should get my parts by monday. I also decided against a mint tin as a case, instead Im going with the box my ipod nano came in. Its clear, and its easy to make a hinge for the lid.


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## puffyx

Hi, nice tutorial!
 Is it ok to use a 4,7K resistor for the led?

 Thank you


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## Fred_fred2004

4.7k will work fine the led might be a little bright is all


 cheers
 FRED


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## puffyx

Ok, I built a cmoy on a stripboard,. but mine does not work 
	

	
	
		
		

		
		
	


	




 But as C1/C2 I bought a 0.1 µF polypropylene film cap (LINK)as seen at tangentsoft's cmoy site. The problem is that I don't measure any voltage on C1/C2.


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## Fred_fred2004

It sounds like a simple wiring mistake, check how the battery is hooked up, some pictures would be a great help if you can get some
 cheers
 FRED


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## puffyx

I'll try to upload some pictures. 
 I can't find any wiring mistakes 
	

	
	
		
		

		
		
	


	




 Could you please measure the voltage on C1 or C2, what values do you have (with nothing plugged tio the cmoy)?


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## scompton

It's a fairly simple circuit. Why not trace back towards the battery, testing for voltage at each point until you find where the problem is?


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## puffyx

Thank you!

 Now it works!
 But I'm not very impressed by the sound quality. ok it's the first test on the x-fi soundcard and my hd 595 cans. no screwing bass


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## Fred_fred2004

Thats not the usual performance I'd say there is still a problem, post some pics, so we can have a look

 cheers
 FRED


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## Fred_fred2004

Trying to find my workbench, I've just come across the original strip board cmoy that I made on page 1

 If you're in Australia and you want a first amp to case up yourself, its not a B22 BUT!!

 Its going for FREE!! 

 it works, uses an OPA2134 same as the pics

 postage $5.00 anywhere in Australia, money donated to a good cause 
	

	
	
		
		

		
		
	


	




 cheers
 FRED


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## audiomonkey

what parts did you use?


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## Fred_fred2004

Common or garden, reasonable quality bits, from the junk box, most of it's in the pics  

 I was really just showing a strip board layout

 cheers
 FRED


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## srserl

I saw this thread back on top today and decided to build a quickie. Never as easy as you think...with all the parts I have, I don't have 2 of the resistor values, and I have no opamps. I was excited to see that I could get 3 of these amps built out of a single $0.89 perf board (making it a strip board with resistor leads on the back).
 I'll put some of those resistors and some different opamps on my next order, just to finish the 3 boards I cut out of the perf board. They should make nice little gifts for a few friends.


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## theSeekerr

Don't get too hung up on the exact resistor values - a step or two either side is probably going to be fine, just so long as you make the left and right channels identical.

 Particularly the gain-setting resistors - who cares if you don't have a gain of 11? That will depend on your headphones and source anyway.


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## kjparker

Hi
   
  I am looking to build my first cmoy.  I am wanting it to be as small as possible, as I want to put it in an Eclipse mints tin.
   
  Can somebody please look at my stripboard layout I have created and tell me if I have made any glaring mistakes?
   
  I'm using a tle2426 to get my dual supply.  I know I dont have the cap shown for the CNR pin on the TLE2426, can someone recomend a value?


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## Avro_Arrow

The data sheet recommends 1uF for CNR, but any value above that should work equally as well or better.
  Also, your gain is pretty high...you might want to consider lowering R4/R4 to 5K.
  I hope you know that C1 is going to be a round can and not a small disc, you might
  want to make more room for it.


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## kjparker

Hi,
   
  Thanks for the reply, yes fully aware that is c1 is a can style, I'll be laying it flat when it's soldered.
   
  I'll take your suggestion on R4, and I'll buy both types.
   
  Other than that, does my circuit look ok?


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## Avro_Arrow

opps...I just noticed that C1 is 470pF not 470uF...


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## Avro_Arrow

The op-amp V+ and V- do not appear to be connected to anything.
  I'm guessing that the red squares mean the strip board is cut at that
  spot.


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## Avro_Arrow

C1 should be 470uF.
  You have it listed as 470pF...


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## kjparker

Quote: 





avro_arrow said:


> The op-amp V+ and V- do not appear to be connected to anything.
> I'm guessing that the red squares mean the strip board is cut at that
> spot.


 


 Thanks,  I'll check that.  Yes the red squares are cuts.  The V- is connected via the link under the socket, I'll have to check the pinout of the chips again, and check for v+, but I thought I had connected it.
   
  I think I just made a typo when I wrote in the value, you are correct on C1


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## Avro_Arrow

The combination of high gain with a low value pot is going to make it
  pretty loud even when the volume is turned right down. You should
  use at least a 20K pot and 200K for R2. A value of .1uF for C2 is kind of
  low, I would recommend 1uF to get the best bass response.
  Which op-amp are you using?


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## Avro_Arrow

Your R3/R4 feedback loop is wrong.


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## kjparker

Quote: 





avro_arrow said:


> The combination of high gain with a low value pot is going to make it
> pretty loud even when the volume is turned right down. You should
> use at least a 20K pot and 200K for R2. A value of .1uF for C2 is kind of
> low, I would recommend 1uF to get the best bass response.
> Which op-amp are you using?


 


 I will be using an OPA2132.
   
  You were right with the v+ line.  I'll add a jumper for that somewhere. 
   
  Those values were just the ones off the tangent recomendations.  I'll post up my parts list shortly


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## Avro_Arrow

I'm sorry to sound so negative...
  But the more I look, the more things I find wrong...
  Please don't get discouraged.
  It's all a great learning experience!
   
  V- Should be connected to Battery -, not TLE out.
   
  You might want to just start again and double check that
  you know where everything is supposed to go...


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## kjparker

Quote: 





avro_arrow said:


> I'm sorry to sound so negative...
> But the more I look, the more things I find wrong...
> Please don't get discouraged.
> It's all a great learning experience!
> ...


 


 Thanks, Not discouraged at all, learning is the name of the game here!
   
  Can I ask what is wrong with the feedback loop?


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## Fred_fred2004

Why not just use the layout at the beginning of this thread, it works fine 
	

	
	
		
		

		
		
	


	



   
  cheers
  FRED


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## kjparker

Quote: 





fred_fred2004 said:


> Why not just use the layout at the beginning of this thread, it works fine
> 
> 
> 
> ...


 

 I was trying to get fancy and make it as small as possible   Big mistake LMAO
   
  Just so I understand your layout, the third row up is your vground?  Is this right?


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## Fred_fred2004

Yes that's the VG, its using the 2 resistors as a voltage divider
   
  How small do you want??
   

   

   
   
   
   
  Thats the smallest I got to 
	

	
	
		
		

		
		
	


	



   
   
  cheers
  FRED


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## kjparker

Nice.
   
  I dont need quite that small.  I want to fit it into an eclipse mints tin.  It will be plugpack powered (I have an 18v brick from an old laptop here).
   
  I can make my layout a little bigger and still fit, but I was hoping to make it as compact as possible!  A bit more playing I think!
   

  
  Quote: 





fred_fred2004 said:


> Yes that's the VG, its using the 2 resistors as a voltage divider
> 
> How small do you want??
> 
> ...


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## kjparker

ok, I re-worked it somewhat this evening, using Fred's layout, and re-reading the schematic as guidance. 
   
  How badly have I screwed up this time? \


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## Avro_Arrow

Thats a lot better, but there is still one mistake.
  Your input/feedback resistors on the left side
  are connected to V- instead of Ground.
   
  Here is a picture of the one I did last year.
  It's not quite as small as the one you are
  trying to do, but it's close...


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## kjparker

Quote: 





avro_arrow said:


> Thats a lot better, but there is still one mistake.
> Your input/feedback resistors on the left side
> are connected to V- instead of Ground.
> 
> ...


 


 Thank you!  Now you have pointed that out I can see it plain as day. (took me about 15 minutes of staring at it to figure out what I had done though!  )
   
  Once I fix that I should be good to go right?


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## Avro_Arrow

yes, I think so.
   
  That was the last mistake I found.
   
  Good Luck!


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## kjparker

ok, I got it built last night.  No pics yet sorry....
   
  It works!  Igiven the size of the PCB, and the locations of the connection points for the sockets and so forth, I cant fit it in the tin I want.  I'll be doing another one with a slightly longer board, this way I can hopefully reduce some of the air wiring!
   
  Thanks guys for all of your help troubleshooting my circuit


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## DarkWinter

These layout do not include the optional R5 does it? I am using the HD448s and this layout makes them WAY to loud to listen to.


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## absoluNewbie

holy cow, this fits into an eclipse tin? we cant get altoids where i am, can you post pics with the board in the tin pls? ty!


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## Fred_fred2004

This is my efforts with an eclipse tin Cmoy
   
  A while ago now, its very tight in the tin and this was the only way I could get it to fit 
   

   

   

   

   

   
  I'm fairly sure I still have the layouts and you more than welcome to them, you'll just need to learn toner transfer 
   
  cheers
  FRED


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## absoluNewbie

yesh please! im sure that's not harder than building the amp itself !! also, part list? thanks.


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## Fred_fred2004

I'll PM you


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## andrewmorio

returning eBay customer.That is so tiny.I hope it is available to buy one day.Sign me up.


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## Fred_fred2004

Sorry mate 
   
  things like that are just done for the challenge of doing it, there's only the one
   
  why not have a crack yourself?
   
  I'll share anything that might help
   
  cheers
  FRED


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## mikkelmmk93

Necrothread 
  But hi all, Have just been reading through all this since someone linked it to me.
  He said that I should use the NJM4556 for the amp. any comments? as to maybe design changes or anything.
  And does anyone have a pcb layout for this amp that I can make myself?


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## skree

saw this thread just now and read it through. I'm going to build myself a stripboard CMOY. Or two. I had to post about that eclipse tin CMOY though that's IT i want that amp.. looks so perfect in that little tin.. beautiful amp.. must set mental note to pm fred when i'm closer to doing that build... simple cmoy first.. once the component shops open


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## WarrenG

Hi
  
 In your schematics you have to pots? is that correct in your other images there i can only pick up one pot.
  
 Regards
 Warren


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## Fred_fred2004

The simple drawing program I used could not do a dual pot so I showed each channel as a single pot, in reality you will use a dual ganged pot
  
 cheers
 FRED


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## Bogaty Smak

Hi Fred.  New to this forum and this thread.  I have been studying the cmoy design for a bit now and I am wondering if there is a specific original description of the basic design somewhere.  My apologies if this question is out of place for this thread.  What I'm wondering is, the Cmoy design seems to be a fairly generic opamp circuit.  What did Chu Moy do specifically to get his name all over it?


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## dawek1

Hey,
  
 Thanks a lot for this project. 
 It works well, but after i take off R7 and R8 and use some cable to connect it. Before this i have distorted music in my phones. 
 I don't now why but it helps and it's working fine now. 
  
 In the beginning i replace resistor few times, with same result.
  
  
 I have question. Do you now why TLE2142CP is not working in this case? Now i use OP275GPZ.
 Do you thing OPA2228P will be better than OP275GPZ? It is 3x more expensive but i don't now that is worthy to invest.
  
 My phones are Ultrasone PRO 900.
  
  
 David


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## kahei036

dawek1 said:


> Hey,
> 
> Thanks a lot for this project.
> It works well, but after i take off R7 and R8 and use some cable to connect it. Before this i have distorted music in my phones.
> ...


 

 Hi David,
 If you are referrinf R7 and R8 stated in first post, those 2 resistors are in the feedback loop, they control the gain of your amplifier. If you get distorted with 10K resistor but not a straight cable (assuming 0ohm), I would suggest you first listen it at low volume, and hear if it distorts. If it only distorts at higher volume, probably the gain is larger than the power supply rail to the opamp that it starts clipping.
  
 What power supply are you using for your cmoy?
  
 TLE2142 is a dual opamp base on its datasheet, and it has a quite low requirement on rail power supply of +-2 to operate. Can't think of a reason it doesn't work while a op275 plays.
  
 Haven't had a chance to hear opa2228. I find OP275 is a little bit colourful with my Beyer cups.
 Or you may want to share your view on OP275 and how you want it to be improved in an opamp thread so that ppl can help you out there.


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## Mr Goat

So im building a cmoy next week if the parts get here. The thing is that im realy bad at understanding "schematics" like the ones they have on tagentsoft's guide. Can i follow this guide but use the part list on tangetsoft?

 also is that design out of date or is it still up to date during 2016?


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## Avro_Arrow

A cMoy is what a cMoy is. It doesn't really go out of date.
 Tangent's guide is pretty good at holding your hand through the process.
 Just read it all the way through.
 Let us know how it goes!


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## serman005

avro_arrow said:


> A cMoy is what a cMoy is. It doesn't really go out of date.
> Tangent's guide is pretty good at holding your hand through the process.
> Just read it all the way through.
> Let us know how it goes!


 

 I would like to jump into this cMoy thing, but how technically proficient and knowledgeable does one have to be to pull it off? I have never before built anything electronically sophisticated. Just how much knowledge is required? Thanks!


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## FallenAngel

serman005 said:


> I would like to jump into this cMoy thing, but how technically proficient and knowledgeable does one have to be to pull it off? I have never before built anything electronically sophisticated. Just how much knowledge is required? Thanks!


 
  
 It's the first step into audio amplifiers, you can do it!  Good luck.


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## kahei036

serman005 said:


> I would like to jump into this cMoy thing, but how technically proficient and knowledgeable does one have to be to pull it off? I have never before built anything electronically sophisticated. Just how much knowledge is required? Thanks!


 

 Cmoy is a very popular circuit due to it's simplicity (which actually is how an non-inverting opamp amplifier operates). There are a number of projects even with layouts on a breadboard. So if you have basic soldering skills, simply follow those guides then solder stuff up, it should able to sing.
  
 If you have little basic knowledge on electronics (like V=IR, voltage divider, etc..). and are more enthusiastic to know more about the circuit, Tangentsoft provides very good explanation to this circuit. After that you should able to know how a non-inverting opamp operates in this circuit, therefore the reason why that value of parts are chosen, and how that parts play its role in the circuit.
  
 It's indeed an entrance to DIY amplifier, highly recommend you to go and do not hesitate in asking questions in the forum. People are more than happy to help you out.


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## tangent

serman005 said:


> I would like to jump into this cMoy thing, but how technically proficient and knowledgeable does one have to be to pull it off? I have never before built anything electronically sophisticated. Just how much knowledge is required? Thanks!


 
  
 That's the first question in my CMoy Pocket Amplifier tutorial FAQ:
  


> This is a somewhat technical project. You won’t need to understand how the amp or its components work, but you will have to be able to follow some pretty exacting directions. If you build it incorrectly, it can take hours or even days of troubleshooting to find the problem.
> 
> Yet, the CMoy is a good choice for beginners because this amp and variants of it have probably been built by thousands of people over the years. Many of these thousands are ready to offer their help in one form or another.


 
  
 My guide is about 15 years old now, and the original project even older, and my guide has received many updates over that time. You should therefore start with the assumption that your question has already been answered in the guide or on the forums.


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## Mr Goat

So im in the middle of building 3 cmoy amps. But i was hoping to use 1 of them as a test bench and test different gains out. In Tangents guide there are 2 resistors you can switch out to change the gain but im not sure which those are in this stripboard design? I would like to think its r5/6 but i just want to confirm it before i start testing 

 Also, is there any real way i can just mess this up so bad that i will destroy my headphones?


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## Fred_fred2004

If you are using the original "Strip board Cmoy" change R5 & R6 to alter the gain
  
 use Tangents formula


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## Mr Goat

I finished the build. But it sound like ****. no bass, vocals is gone mids and highs are gone. there is no difference between left and right Something in the build is wrong.

A fellow member on diy audio told me its probably a grounding issue. But having more sets of eyes while trouble shooting won't hurt  

I checked this list off 
1/ Switch off and remove the batteries.

2/ Have your meter set to a low ohms range.

3/ Now check that the red wire in the first picture (the one with the headphone socket) goes to the 'virtual ground point' which is the junction of C1+ and C1- in the diagram you linked to in post #3.

4/ Check that the wire's going to the volume control (the pins that are joined and with those two blue and two red wires attached) also go to the virtual ground.

5/ Check that the input grounds also go to this same point.

6/ Now power it all up.

7/ Set your meter to DC voltage and connect the black lead to the virtual ground point. 

8/ Check that you have +9 or so volts on pin 8 of the opamp.

9/ Check that you have -9 volts on pin 4.

10/ Check that the voltage on pins 1,2 and 3 is zero and that the voltage on pins 5,6 and 7 is zero

Done it. and everything looked good, 8 and 4 is shoring 9v and the rest is at 0.02ish. But there is 1 thing im not sure about. My 6.3mm output, if i use my dmm and try to measure between the points marked(https://gyazo.com/4a1cdac7c91e423cd065b3b7bf42f0e6). i get no reading at all, which means that i don't have a connection right? Can this be the problem?


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## Mr Goat

Fixed it, turned out it was the op275 messing everything up, tried both ones i had, both resulted in the same distortion. I just switched it out to a tle 2082cp and it sounds great


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