Does Op-amp Rolling Work? [Video]

[solderdude]

It seems auto-scaling was used.
This makes it hard to compare plots.
Can you use the same scales ?

As mentioned before... the performance of this amp is limited by the class-D output stage not by the op-amps, they won't change anything.

Someone mentioned he would like to see the difference when another (than stock) power supply was used.
Maybe you have a decent lab power supply floating around and are willing to test if that changes the sound ?
I expect not to see any differences, at least not at 5W but maybe at or near full power (current limiters kicking in).

 

[pma]

This time a different 5532 and
OPA2134
LN4562 this one was maybe one SINAD point less than the others
OPA1656

Interesting that the 4562 is the worst of those, though the differences are small and cannot be used to explain possible sound differences, if they exist. Is the 4562 a genuine part? Is it stable in the DUT?

Auto scale is not a big issue, it is easy to use one’s brains.

 

[DualTriode]

There was no auto-scaling, just my eye and mouse get the credit.

Next time I will attempt to save a blank plot and append the measurements on the saved prescaled plot.

@pma, the 4562 arrived on my door step directly from Mouser.

 

[pma]

@pma, the 4562 arrived on my door step directly from Mouser.

It is interesting, compared to some of my results:

Big test of DIP dual op-amps for audio: LM4562, NE5532, OPA2134, TL072 and LM1458

Not worth much. Thers this BS to start. "However, despite of all these advantages, they are practically devoid of any sonic signature so they require an external input buffer to tuning in a “warm house sound”, customizable according to tastes and requirements." And get this, $300 for a tiny...

www.audiosciencereview.com

But it may be an interaction with the sub-optimal DUT that you have tested.

 

[DualTriode]

In a previous post I speculated about more power changing the distortion profile.
I did not hear a difference, the 250 Watt Dale load resistors went from warm at 5Watts to hot to the touch at+140 degrees F.

For grins in an effort to keep the scale the same I tested the stock NE5532 and OPA1656 Op-Amps at three different input voltages:

0.5volts
1.0volts
2.0volts

See attached

 

[pma]

It would need a deeper analysis and first the knowledge of the A5 circuit schematics. Otherwise these are blind attempts.

 

[solderdude]

I would suggest to put a probe on the output of the buffer op-amps and show the performance of that signal if the goal is to gauge the performance of an op-amp in this particular circuit.
Now all that appears to be measured is the output stage performance which most likely has the op-amp performance hide behind (below) it.
In other words what is measured is the output stage.

 

[pma]

Now all that appears to be measured is the output stage performance which most likely has the op-amp performance hide behind (below) it.
In other words what is measured is the output stage.

Yes. However, op-amps may make a measurable difference if swapped in the power amplifier, but, the output stage has to have very very low distortion. Necessary condition is that the DUT is stable after op-amp swapping. Below the proof (1kHz):

It is also a result of op-amp output loading by output stage non-linear input impedance. The whole topic is not to be trivialized, as is sometimes a case here.

 

[solderdude]

Yep circuit dependent..
In this test the performance also seems limited by the output stage (simple input buffer).

In other cases another (suitable) op-amp could make sense (measurement wise and above all overload wise)

 

[DualTriode]

For grins.

I found a OPA 1612 on a adaptor board, warmed up the tools and A5 amplifier.

The results are not even a gnat's eye lash different.

The measurement was the amplifier output (5 Watts) into a dale NH 250 1% 4 R resistor as recommended by Audio Precision.

No speakers were connected, no listening tests were performed.

Can you hear a difference? Not likely but no one knows

See FFT below.

Thanks DT

 

[pma]

- you are testing in a product that has not SOTA parameters
- you are showing 1kHz spectrum only

I do not expect that in this amp would op-amp swapping make a difference. But in a preamp with much lower distortion it may make a difference:

Can you hear a difference between OPA2134 and LME49720 in the PRE-TC10?

The op-amps OPA2134 and LME49720 were swapped in the Audiophonics PRE-TC10 preamp and the files (matched and aligned) were recorded and uploaded to: https://drive.google.com/file/d/1CI7NjcYyL323qeCFDxj3MtSkfcfu4GNU/view?usp=sharing Can you hear any difference? This is how they measure: And...

www.audiosciencereview.com

 

[DualTriode]

- you are testing in a product that has not SOTA parameters
- you are showing 1kHz spectrum only

I do not expect that in this amp would op-amp swapping make a difference. But in a preamp with much lower distortion it may make a difference:

Can you hear a difference between OPA2134 and LME49720 in the PRE-TC10?

The op-amps OPA2134 and LME49720 were swapped in the Audiophonics PRE-TC10 preamp and the files (matched and aligned) were recorded and uploaded to: https://drive.google.com/file/d/1CI7NjcYyL323qeCFDxj3MtSkfcfu4GNU/view?usp=sharing Can you hear any difference? This is how they measure: And...

www.audiosciencereview.com

Hello,

I have no expectations that differences among OP-Amps would be audible with this A5 amplifier even if there were speakers connected.