[Lewy5]

I recently replaced both op-amps in my Omega 3 440 the 8Pin socked AD847 with LME49720NA because the amp was chirping very loudly on the right channel when I turned it off. I believe it to have been resonance related but although it sounds good now, but it could be better and the chirping is gone, I wonder if anyone knows a better op-amp to use in that amp?

[I.Greyhound Fan]

Look at Sparkos or Burson op amps.

[Jon L]

If you have a few minutes, you might look at this thread 

https://www.head-fi.org/threads/orgy-of-opamps-discrete-opamp-comparison-thread.977578/

[Lewy5]

The Burson's and Sparkos are expensive and I'm not sure either can handle the heat  or drive enough current into the circuit. Both the AD827and the LME 49720 are bi-polar with the AD827 , which I've replaced, driving up to 32ma and the LME49720 (same as LM4562) driving 26ma max. However the LME specs for max 85C vs 70c for the original AD827 which Frank had glued heat sinks onto. So far the LME opamps sound better than the originals. Every bifet opamp  I put in sounded crappy?

The Omega 3 amp universal amp schematic can be found half way down or so here: https://www.audiocircle.com/index.php?topic=185711.0
as well as several great pictures,I hope it helps somebody, especially if they can intern help me.
 

You can still buy the LME749720 and LM4562 8 pin DIPS on Digikey.

I Think I need a bipolar opamp rated for at least 85C, any suggestions? I know it could sound better!

[Lewy5]

Just to update I did get some Chinese 8 pin dip mounted opa1622 op-amps with two resisters ? and two capacitors 01c on a small circuit board which only seem to filter 100k+ ?  and above but , from Aliexpress, never the less After I removed the excellent LME49720's I had in it and  plugged them in the amp. Well, it sounded great, simply great. More detail was there as well as seemingly more tube like harmonics. I think larger caps maybe 1mfd etc would make for  better filters but it seems they meant nothing in this circuit?

I didn't expect much suspecting that they might be fakes, less than $20 shipped, but I believe that the Omega 3 never sounded better and don't think it could really. The opa1622  is rated for 125 degrees C  or 257 degrees F vs 70c for the AD827 and has great specs and is often used to drive headphones. But, is not for all circuits, so next I will try them on my Fosi ZA3 as well as the LME49720's. So far that cheap little amp amp amazes me for the price and drives my Von Scweikert VR2 speakers well but not my NHT 3.3 speakers which are in a much bigger room etc.. But I think either two of them in mono  or better yet  two Fosi mono V3's could do the job although not with the tube like sound.

My search for the best op-amp to replace the original AD827's is over and I am  happy. It was actually an easy fix and very worthwhile upgrade, imho,  because Frank had mounted both of them them in sockets right in the middle of the two circuit boards.

I have always liked the sound of tubes and had built my first  kit a Dynaco 70 when I was 12/13 but Tubes need
highly efficiency speakers to sound their best and even KT88's are good for only about 40-50 watts a channel which can current starve a lot of woofers. Mosfet amps like my Omega 3 440 (220w into 8 ohms) are very inefficient, hot running, power hogs, just like tubes, but they sound a lot  like tubes too and can drive very inefficient speakers easily. Unlike regular transistors mosfets are easy to parallel too. I just love their even order harmonic tube like distortion. It might not be for every body but it is what I grew up hearing so it might be a required taste? There is no perfect system but for tube like sound go tube or mosfet imho.