Unusual amp from 1987

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Sorry Maxim, I should have listened to you.
With diode.
Much better waves now.
 

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Wow. Qhex with diode gives the lowest distortion and the most beautiful THD profile among all versions. Incredible. Waiting for listening impressions.
 

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minek,

Yesterday I was already playing with the sim and sent you the asc file with D5 added to the schematic and also D8 changed to a RED LED to see how distortion profile has changed.

Today, I replaced Q2 for 2SA1381C, distortion profile is much better indeed.
 

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> R10/R11 is reduced to 51/100 ohms.Distortion will decrease dramatically. But the heating of transistors will increase. Diagram from post 326

Yeah, who needs hotter transistors...
Distortion is already very low, I'm fine with these numbers.
150/75 Ohm was a compromise between low(er) heat being dissipated, and distortions.
It's just a sim, real Thd numbers will be totally different story :)

Later on, I'm going to measure this amp with audio analyzer, let's see if real numbers are as good as the sim.

I tried these op-amps (no music, just oscilloscope):
1) TL071 - very good, as usual
2) TLE2081 - same
3) TLE2071 - same
4) LT1357 - not good, oscillations
5) LF356 - very good, waves looking kind of better
6) LT1056 - very good (when I tried it in LMK amp, it was not stable)

So basically, all of them look the same on the oscilloscope with the exception of 4) being bed, and 5) being the best in my non-scientific gut feeling.
Slew rate is the same, more or less, on all of them.

Will repeat the same test with music, later on.
 
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Later on, I'm going to measure this amp with audio analyzer, let's see if real numbers are as good as the sim.

I tried these op-amps (no music, just oscilloscope):

3) TLE2071 - same
4) LT1357 - not good, oscillations
5) LF356 - very good, waves looking kind of better
6) LT1056 - very good (when I tried it in LMK amp, it was not stable)

.

RC correction can be set between the inputs of the operational amplifier. 100-1000ohm and 5-20pF. From your division, for example LF356/ very good OU. I will add OPA132/opa134 amplifiers to your list