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Ultimate cMoy op-amps

post #1 of 15
9/5/07 at 1:54pm
Thread Starter 
What parts list do you use? What amp etc.

I'm getting a parts list together for cmoy #2 and #3 and I want to improve where ever possible.

If you were to build the Ultimate cmoy what would you use?
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post #2 of 15
9/5/07 at 1:58pm
ultimate cmoy?

you mean, without turning it into some other amp entirely?

Start by using a high-current opamp. opa552 if the gain is going to be 6 or higher, opa551 if it's going to be 5 or lower.

Note that these are only available in single-channel packages, there isn't a dual version.

Someone who believes in boutique capacitors will tell you to use black gates for the power supply caps, maybe teflon for the input coupling caps.

And don't forget your tantalum resistors.

Better yet, spend less money building an amp that's better than a cmoy.
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post #3 of 15
9/5/07 at 3:50pm
Thread Starter 
haha I agree w you on building a better one for less. I'm just ordering parts for the 2 extra boards I have and want to improve where ever possible without going crazy. these are practice for a CKKII I have sitting in the closet waiting to be built. I'm going with larger caps and different op-amps. Not sure what 2 channel 8 pin options there are though.

James
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post #4 of 15
9/5/07 at 3:58pm
opa2107, ad8620 (on browndog adapter), opa2228 (if the gain is higher than 5 - and you might want to look at the datasheet and make use of tangent's dc offset calculator).
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post #5 of 15
9/6/07 at 4:19am
The only ones I've listened to are: OPA2277, OPA2227 & LM4562 (AD8066 soon as I put it on adapter)
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post #6 of 15
9/6/07 at 10:17am
Thread Starter 

which do you prefer?

Quote:
Originally Posted by Joshatdot View Post
The only ones I've listened to are: OPA2277, OPA2227 & LM4562 (AD8066 soon as I put it on adapter)
Hey Josh which do you prefer? Also do you have a part # for adapter?

James
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post #7 of 15
9/6/07 at 11:53am
Yeah, the lm4562 is great, but if you plug low-impedance 'phones into it, not so great anymore.
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post #8 of 15
9/7/07 at 3:29am
Quote:
Originally Posted by ericj View Post
Yeah, the lm4562 is great, but if you plug low-impedance 'phones into it, not so great anymore.
Truedat! My FX33's in my CMoy distorted/clipped with the LM4562. I hope the Optional R5 @ 50 ohms will fix this issue.

Look at Tangent's site for the Browndog Adpter.
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post #9 of 15
9/7/07 at 6:03pm
Quote:
Originally Posted by ericj View Post
Better yet, spend less money building an amp that's better than a cmoy.
A better amp that's cheaper than a CMoy, or were you considering the added cost of boutique/expensive parts?
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post #10 of 15
9/10/07 at 4:41pm
I would say that the ultimate cmoy had a ppa like ground, opa617's, is buffered and uses nice input caps

I'm making such a cmoy now
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post #11 of 15
9/10/07 at 6:12pm
Quote:
Originally Posted by exphy View Post
I would say that the ultimate cmoy had a ppa like ground, opa617's, is buffered and uses nice input caps

I'm making such a cmoy now
Right, see, that's not a cmoy anymore.
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post #12 of 15
9/10/07 at 6:26pm
I read somewhere that the opa2107 is unstable at +/- 4.5 Volts. I use it with 2x9V, but never tried it at 9V.
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post #13 of 15
9/10/07 at 6:40pm
not unstable, but heavily distorted. yep, you can't use it at 9v
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post #14 of 15
9/10/07 at 6:50pm
Well, you can run it at 9v, but it's a waste of money.
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post #15 of 15
9/11/07 at 9:37am
OPA2107 will not distort heavily at 9 V supply, not in my amps. It's specified for 9 - 30 V supply. It sounds a little better at higher voltage supply. It could be a waste of mony anyway unless you like a dark and less detailed sound. It's strength are a warm and "euphonic" signature with a very wide sound stage.

OOPS! I forgot this was a CMOY thread, I've only tried it in front of buffers. Sorry. You're probably right about dist in a CMOY.

Anyone tried AD8599 in a CMOY? it could be a killer.
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