[majkel]

Filburt is right. Some day all DIYers realize that TRUE amplification started on the day they dropped in AD8397 and all before was cheating themselves they had build an amplifier. Cmoy may act as an amplifier when compared to low power mp3players having a couple of miliwatts output, and that's all. And yes, chips working close to their current limits distort significantly. This is the case with all plain audio and non-audio op-amps. Regarding OPA2227 it is not that slow. OPA2277 is intended for precise DC devices but this chip is totally unsuitable for audio IMHO.
What I suggest is copy all voltage feedback from low-noise PINT version and use AD8397. As a virtual ground - op-amp + BUF634 or Sijosae AB Virtual Ground with electrolytic caps on output side, no cap divider before transistors! It is wrong and screws up idea of the circuit. Trust an electronic engineer.

 

[balou]

majkel, is your post about amps in general or just about unbuffered amps?

Quote:

As a virtual ground - op-amp + BUF634 or Sijosae AB Virtual Ground with electrolytic caps on output side, no cap divider before transistors!

um, could you explain this? you mean caps between the buffers and the headphone ground?

 

[majkel]

Quote:

Originally Posted by balou /img/forum/go_quote.gif majkel, is your post about amps in general or just about unbuffered amps?

It was about unbuffered amps. If you have an additional buffer (chip/discrete) you use and enjoy any op-amp, AD8397 being inadequate then.
Quote:

um, could you explain this? you mean caps between the buffers and the headphone ground?

I mean doing it exactly like in sijosae Virtual Ground drawing. Tangentsoft gives discrete Virtual Ground drawing with capacitors on the wrong side. Actually, they both work but sijosae sounds better.

 

[balou]

The AD8066 sucks... I have to rerip several albums with higher bitrate.
Nothing but problems with all this audiophile stuff

...



majkel, I now see what you mean. seems like a mistake by tangent. but I think one big cap rail to rail would be the better solution anyway. maybe coupled with two small rail-to-gnd caps, like in the mini³ v2

 

[Filburt]

I'd recommend the LMH6321 over the BUF634, personally, if you're planning to use an IC buffer.

 

[Joshatdot]

Quote:

Originally Posted by majkel /img/forum/go_quote.gif Filburt is right. Some day all DIYers realize that TRUE amplification started on the day they dropped in AD8397 and all before was cheating themselves they had build an amplifier. Cmoy may act as an amplifier when compared to low power mp3players having a couple of miliwatts output, and that's all. And yes, chips working close to their current limits distort significantly. This is the case with all plain audio and non-audio op-amps. Regarding OPA2227 it is not that slow. OPA2277 is intended for precise DC devices but this chip is totally unsuitable for audio IMHO. What I suggest is copy all voltage feedback from low-noise PINT version and use AD8397. As a virtual ground - op-amp + BUF634 or Sijosae AB Virtual Ground with electrolytic caps on output side, no cap divider before transistors! It is wrong and screws up idea of the circuit. Trust an electronic engineer.

I am just making the standard CMoy design with a TLE2426 instead of the resistor divider. If I were to totally redesign my PCB for the BUF634 or Sijosae AB virtual ground, there'll be a extra $5 processing charge for the new files processing of the same board we already accepted for manufacturing.

 

[Earwax]

Sorry for dredging up such an old thread, but I wanted to stick in my 2 cents and vote for the TLE2072 as the best cheap opamp for a 9V cmoy. I must have tried 20 different opamps, and I thought the TLE2072 is best. Try it!

Dual OPA627 and the OPA2107 may be better if you have more voltage and more $, but then at that point you're probably moving on to some other design anyhow.

 

[onesandzeros]

Quote:

Originally Posted by Earwax /img/forum/go_quote.gif Sorry for dredging up such an old thread, but I wanted to stick in my 2 cents and vote for the TLE2072 as the best cheap opamp for a 9V cmoy. I must have tried 20 different opamps, and I thought the TLE2072 is best. Try it! Dual OPA627 and the OPA2107 may be better if you have more voltage and more $, but then at that point you're probably moving on to some other design anyhow.

I'm glad you did dredge it up, I was looking for this sort of info a few months ago when I built a cmoy... Good discussion.

 

[simssmo]

Hi I'm new to the site, I bought a cmoy from ebay and wanted to upgrade the opamp

From what I've read so far AD825 is the best opamp, however, will it work in my cmoy.

It currently has an OPA2134PA on a DIP-8 IC socket.

I've visited this site http://www.analog.com/en/amplifiers-and-comparators/operational-amplifiers-op-amps/AD825/products/product.html but I'm not sure which 8 pin one to get.

Any advice is welcome, also does anyone know where to get these opamps from as I live in the U.K.

 

[gurusan]

They have it at farnell ANALOG DEVICES | AD825ARZ | Amplifiers & Comparators | Semiconductors - Integrated Circuits | Farnell UK

but you will need a browndog adapter

 

[simssmo]

thanks gurusan

 

[marksk]

Quote:

Originally Posted by Earwax /img/forum/go_quote.gif Sorry for dredging up such an old thread, but I wanted to stick in my 2 cents and vote for the TLE2072 as the best cheap opamp for a 9V cmoy. I must have tried 20 different opamps, and I thought the TLE2072 is best. Try it!

can i use tangentsoft's schematic or do i need to use a different one for the 2072?

 

[cobaltmute]

It is dual so you can use it in Tangents tutorial

 

[joms]

Hi guys, what opamp would you recommend me to put in my sub output? I will use it on the addon card of my Asus Xonar Essence.
 
Asus Xonar Essence ST = 2x OPA2137P + 1xLME48720NA
Asus Xonar H6 Addon card (sub out) = ???
 
For Computer setup:
My front speaker = audioengine 2
My subs = Velodyne Impact 12
 

 

[FallenAngel]

Uhm... I always thought the 137 was a terrible opamp, you're using it or it came stock?
I generally like the AD825