Does Op-amp Rolling Work?

[amirm]

Not that I can think of. Do you have a link for it?

 

[SnakeLord]

Not that I can think of. Do you have a link for it?

3e Audio TPA3251 TPA3255 Finished Amplifier with PFFB is coming!

No additional features, no sub out, no nothing. No power supply options to save 10$ - just offer the biggest one that really supports the specifications - and these should be honest. Overall, a simple product that focuses on quality and power for an affordable price, and just works Fully agree...

www.audiosciencereview.com

This was tested by e3 on their A5 prototype.

 

[solderdude]

So are there any other plausible reasons for the slightly better results of the OPA15xx besides some change of the testing conditions

As the voltage on the opamps is much higher than the signal voltages they will never reach clipping levels.
Most likely scenario is that the power supply conditions of the test amp was not the same or different amps were even used.
I see no reason what else could cause different clipping levels of the output stage (3255) when only the input opamps were swapped.

It is probably safe to disregard the difference in clipping points (looks like 2 different amps or the same amp but different power supply was used.
In that case what the plots show is NO difference between the used op-amps which makes sense as the TPA 3251 that comes after the op-amps is basically the 'bottle neck'.
All mentioned op-amps (aside from the Muses 02) are 'better' than the TPA 3251 at 1kHz for the A5 prototype.

 

[Groovy]

Today, I replaced the built-in NE5532 op-amps in my 3EAudio A7SE with OPA1656 op-amps.
I recorded a song using both op-amps at the same volume level with a Tascam field recorder and its built-in unidirectional microphones on my sofa.
Here is a link to download the MP3 file (valid for 7 days). Who can identify the OPs?

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[LTig]

Today, I replaced the built-in NE5532 op-amps in my 3EAudio A7SE with OPA1656 op-amps.
I recorded a song using both op-amps at the same volume level with a Tascam field recorder and its built-in unidirectional microphones on my sofa.
Here is a link to download the MP3 file (valid for 7 days). Who can identify the OPs?

HiDrive Share: Kostenlos große Dateien versenden

Filesharing ganz einfach: Mit HiDrive Share senden Sie große Dateien ✔ kostenlos ✔ ohne Anmeldung ✔ sicher & schnell über deutsche Server. Jetzt starten!

get.hidrive.com

It's unlikely that someone is able to hear a difference with any distortions being swamped by 3 transducers in the chain (your speakers, your microphones, and my headphones or speakers).

 

[notinuse]

It's unlikely that someone is able to hear a difference with any distortions being swamped by 3 transducers in the chain (your speakers, your microphones, and my headphones or speakers).

Yep, some people need to get a grip.

 

[Multicore]

Today, I replaced the built-in NE5532 op-amps in my 3EAudio A7SE with OPA1656 op-amps.

Groovy!

I recorded a song using both op-amps at the same volume level with a Tascam field recorder and its built-in unidirectional microphones on my sofa.

Even more so!!

I'm ready to bet that the differences in the recordings due to differences in the acoustic space (e.g. you and or the mics being in a slightly different position) far exceed those due to the op amp devices.

 

[Groovy]

I'm ready to bet that the differences in the recordings due to differences in the acoustic space (e.g. you being in a different position) far exceed those due to the op amp devices.

I agree with you. However, I was standing in the same spot behind the recorder during both recordings.
In any case, I have trouble hearing any difference with my old ears.

 

[rsqt]

Today, I replaced the built-in NE5532 op-amps in my 3EAudio A7SE with OPA1656 op-amps.
I recorded a song using both op-amps at the same volume level with a Tascam field recorder and its built-in unidirectional microphones on my sofa.
Here is a link to download the MP3 file (valid for 7 days). Who can identify the OPs?

HiDrive Share: Kostenlos große Dateien versenden

Filesharing ganz einfach: Mit HiDrive Share senden Sie große Dateien ✔ kostenlos ✔ ohne Anmeldung ✔ sicher & schnell über deutsche Server. Jetzt starten!

get.hidrive.com

If there are differences that could be noticed, the 3255 has to be able to show them, but there is the bootleneck.

 

[Groovy]

If there are differences that could be noticed, the 3255 has to be able to show them, but there is the bootleneck

Of course, but that should apply to any power amplifier stage, not just the TPA3255.

 

[RandomEar]

I agree with you. However, I was standing in the same spot behind the recorder during both recordings.
In any case, I have trouble hearing any difference with my old ears.

If you move a literal inch, the treble response can change measurably. Acoustic measurements are quite finicky. I get the sentiment, but recording this through speakers and mic, including all room reflections, the noise floor of your environment, amp and ADC is just the wrong way to compare this stuff. Use a level shifter and capture the signal directly at the speaker terminals on the amp, everything else is just a wasted effort.

In any case, people have already done this with various amps [1, 2]. The results are pretty boring, with a few notable exceptions of bad pairings causing an "explosion" of the distortion numbers. If you don't have the equipment to measure this in-circuit and lack the ability to reverse-engineer the PCB and simulate the results of op amp swapping, the only sound suggestion is not to do it. The likelyhood of making the device perform identical or worse is significantly higher than making it perform better in any aspect. On top of that, the likelyhood of making it perform audibly better is almost always zero but the likelyhood of causing a vast increase in distortion or even oscillations is far above zero.

 

[Mnyb]

Yes the distortion in the speakers alone can be hundreds of times that of the amps and then the music hits the room… and the mic ?
And the brain is involved if your listening in a space and then a recording made in that space it would not sound the same .
You brain can filter out stuff while you sit there often to your benefit our hearing has some cool features it allegedly weight factors as direct vs reflective sound and discard ”stuff” . Microphones does not do that hence why all YouTube videos of some recording the in room sound is just nuts ( and then crunch it trough YouTube compression algorithms ) .

And in higher frequencies, I would say millimetres not inches can make a difference, just your position vs the microphone alters the recording, possibly not audible, but anyway a bigger diff than the op amps

No subtlety would survive in room recording especially differences in electronics .

 

[Groovy]

Thank you for your responses. The recording (made with the fairly high-quality) Tascam DR-100 MkIII was an attempt to enable a direct comparison.
Your objections make it clear to me that the errors produced by the recording result in a comparison that, while allowing for an audible comparison, actually provides little real insight.

At least, the experiment has shown me that the NE5532 used by the manufacturer is a good choice and that replacing it doesn’t make a difference.

 

[MAB]

Thank you for your responses. The recording (made with the fairly high-quality) Tascam DR-100 MkIII was an attempt to enable a direct comparison.
Your objections make it clear to me that the errors produced by the recording result in a comparison that, while allowing for an audible comparison, actually provides little real insight.

At least, the experiment has shown me that the NE5532 used by the manufacturer is a good choice and that replacing it doesn’t make a difference.

Yeah, hard to improve over an NE5532 for most audio purposes.

I can give examples of OpAmps that don't perform quite as well, earlier in this thread I compared NE5532 to TL072:

Does Op-amp Rolling Work?

The Chinese are said to be very skilled people, you know?

www.audiosciencereview.com

The NE5532 is about 0.89dB better than the TL072 in the Left channel, 1.35dB better SINAD for the left Right channel. This is a tiny difference, but why does the NE5532 advantage grow in the Right channel?

It turns out the Right channel of the preamp uses a different resistor network than the Left, because I wanted to test out advantages and disadvantages of lower feedback resistor values:

If you do a sweep and measure SINAD vs. level, you can see the TL072 show rising distortion above 2V for the Right channel with the low feedback resistor (Yellow trace):

So the TL072 does have a small performance disadvantage using low feedback resistance under very specific operating conditions. For audio, 2V single-ended would be max volume in most cases, so good luck going deaf trying to hear this! And the small improvement using low feedback R is also a nothingburger with the NE5532. It's a technically interesting difference, well-below the outer-reaches of audibility. I have a few of these tests with a range of different OpAmps.

Sparkos SS3602 Opamp Rolling In Fosi P4

Beginning to? It has for several days weeks already! :facepalm: I have a very high tolerance for behaviour that looks trollish, but might just be ignorance. That tolerance - in this case - is pretty much consumed.

www.audiosciencereview.com

Sparkos SS3602 Opamp Rolling In Fosi P4

1% is four orders of magnitude, even less audible. You also need to take the Klippel distortion test to inform yourself how much distortion is actually audible. You can't pass 80dB even with a pure tone. If you can, please post your results. Someone pointed this out to you earlier when you...

www.audiosciencereview.com

So imagine trying to measure these differences comparing 4 parts per million to 6 parts per million SINAD. There are so many variables for the speaker and room, it would take a really careful measurement in an environment controlled for sound, temperature (driver and room), electrical interference of the mic (LED lights for example), and of course the speaker's distortion, which is 100-1000 times the difference we are trying to measure.

Some circuits may benefit from a different OpAmp, and often need specific layout and feedback to achieve these good results. MC preamps are one example, in those cases adding a swappable socket is counter-productive since sockets have their own intrinsic performance deg, and presumably they designed around a specific high-gain circuit that needed specific components to perform, if performance is what we are looking for.

edit: got Left and Right mixed up

 

[Groovy]

That was a very interesting test.
My amp should deliver an output voltage of nearly 30 V RMS at 1.1 V RMS input voltage.
So the distortion values you measured can really be considered negligible.

 

[Ruediger]

Today, I replaced the built-in NE5532 op-amps in my 3EAudio A7SE with OPA1656 op-amps.
I recorded a song using both op-amps at the same volume level with a Tascam field recorder and its built-in unidirectional microphones on my sofa.
Here is a link to download the MP3 file (valid for 7 days). Who can identify the OPs?

Even if you grabbed the signal directly at the analogue ouput I don't think it works this way. In any case too much happening behind those opamps that would steal any possible show.

But I like the idea to put their performance into files so a closer look is possible. Would have to be lossless/hi-res though. And I imagine the location of a scientific valueable grab as something suited for a lab/testing place and not really doable for the home user.

 

[Mnyb]

I have no problems with you guys designing circuits and measure this stuff and design new interesting circuits and measure them to ! its a a hobby

But in the end as i vented several times it's noting an end user of a pre built products should be bothered with , by himself or the manufacturer .

Some brands contribute to this fud either by providing a socket and design the product around a handfull of "safe" options. The bad thing here is that the circuit may not be fully optimized and has to include a socket . its simply cheaper and better to do the design properly .
And then the user buy a new interesting OP that's not on the the "safe" list and blow up something , bad idea.

And some manufacturer of class-D amps offers input buffer options ? Make the best design you can instead and don't have 5 different products that must be tested and maintained . It's just options for the sake of options, fooling the end customer into thinking he can customize the sound in some way and have an influence. It's purely catering to the audiophile ego of the end customer dishonest practice ! , have more colors on the case instead ? and make all products with the best buffer that would be cheaper.

 

[SnakeLord]

It's just options for the sake of options, fooling the end customer into thinking he can customize the sound in some way and have an influence.

But what if it sells and there are many crazy people around happy to buy it?

 

[jareinertson]

But what if it sells and there are many crazy people around happy to buy it?

In a serious note, perhaps enabling such ideas and profiting from it is not in the best interests of the individuals or society…. But then there always seems to be crazy people around…