AD826 vs OPA2134 - listening test

[ashok]

I have used the following as the buffer gain stage between a passive LC filter and the power amp. The DAC is a TDA1541.
1. OPA2134 gain stage with voltage series feedback.
2. AD826 used instead of the the OPA2134.
3. 6SL7 tube SRPP gain stage with voltage shunt feedback.
So I can use any one of these ( one at a time !).

The AD826 seems to be smoother than the OPA in the voice range. But deep bass and transients seem more punchy in the OPA2134. The difference is audible and I would like to know why. Only the chips are changed. So what's happening?

The tube stage beats the AD and the OPA by miles. The vocals are superb and transient attack and deep bass are incredible. The tube however would loose out in the distortion and signal to noise figures. Who cares , under normal ( loud) listening levels I can't hear those problems. So all the opamp IV users try out a simple tube stage. You might be in for a shock !
That's what's great about audio. At every turn there's something new. It will outlive me and that's what I want.
Cheers.

 

[PMA]

The answer is difficult and the exact answer is impossible. But you are completely right, chips do sound different, even the best types. I have collected enough experience with this phenomenon when developing Audio Buffer (see my www). It is interesting to try OPA627, OPA602, AD8610. But AD825 seems to be the winner (it is not a single version of AD826, it is completely different amp). Probably the great set of op amp parameters must be perfect and balanced. The speed, smooth transient response and ability to deliver enough current seems to be of great importance as well, of course the very low distortion.

 

[analog_sa]

Ashok

Your experience just states the obvious: different opamps sound different (surprise?) and valves sound better than opamps (bigger surprise?)
If you try a better valve/topology than 6SL7 SRPP with NFB you'll discover that there is still room for improvement (lots)

 

[stokessd]

If you try a better valve/topology than 6SL7 SRPP with NFB you'll discover that there is still room for improvement (lots)

Don't sell that topology short, it can be a very good performer. I'd take it over a lot of others.

Sheldon

 

[fmak]

The AD826 seems to be smoother than the OPA in the voice range. But deep bass and transients seem more punchy in the OPA2134. The difference is audible and I would like to know why. Only the chips are changed. So what's happening?

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The AD 826 is bioploar, has much higher bandwidth than the OPA2134, and much lower open loop gain. It also seems to have a simpler circuit schematic.

I find the 826 excellent for I/V conversion, but slightly sharp for filter/buffer use. The OPA2134 is nowhere as 'music' friendly and sound more 'shut in'.

Tube stages have their own colourations as well; appeals to many.

 

[AudioEngineer]

I have used the following as the buffer gain stage between a passive LC filter and the power amp. The DAC is a TDA1541.
1. OPA2134 gain stage with voltage series feedback.
2. AD826 used instead of the the OPA2134.
3. 6SL7 tube SRPP gain stage with voltage shunt feedback.
So I can use any one of these ( one at a time !).

The AD826 seems to be smoother than the OPA in the voice range. But deep bass and transients seem more punchy in the OPA2134. The difference is audible and I would like to know why. Only the chips are changed. So what's happening?

The tube stage beats the AD and the OPA by miles. The vocals are superb and transient attack and deep bass are incredible. The tube however would loose out in the distortion and signal to noise figures. Who cares , under normal ( loud) listening levels I can't hear those problems. So all the opamp IV users try out a simple tube stage. You might be in for a shock !
That's what's great about audio. At every turn there's something new. It will outlive me and that's what I want.
Cheers.

Try limiting the bandwidth of the AD826 and listen to it again.