Does Op-amp Rolling Work?

[Haskil]

Right now I am using BT from my laptop to my speakers over airplay because of the delay where it mucks up video calls. Because my stero is behind me, I don't want to run a wire in the walls/ceiling to connect them.

Airplay doesn't work over Bluetooth, but it does over Wi-Fi. Airplay 1 is Apple Losless. Airplay 2 can transmit in AAC depending on the case.

 

[horias2000]

Fosi Audio Box X5 Phono Preamp Review

This is a review and detailed measurements of the Fosi Audio Box X5 stereo Phono stage. It was sent to me by the company and costs US $109.99. Company manages to bring a touch of class in a category that is universally utilitarian with those rounded corners and orange power button. Flexibility...

www.audiosciencereview.com

you may need to read carefully this thread...

and the efforts from pma:

Measuring noise and SINAD of MM phono preamps properly

Measuring noise and SINAD of MM phono preamps properly 1. Intro It is a temptation to measure phono preamplifiers the same way as if it was a common link stage preamp, to drive it from very low generator impedance and to measure the preamp output voltage. Similar way as when measuring with AP...

www.audiosciencereview.com

;-)

The Fosi Audio X5 phono stage has great measurements as has the PHONO stage I designed and built. The good results of the Fosi Box are mostly due to the OPA1612 that they use. In my design I use LM4562 that has slightly worse THD and noise but it still does a great job.

As for PMA's post, I haven't seen it until now. That is a great read. I'll go through it for sure. Thanks for pointing it out.

 

[Sjkrabbe]

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs and Power Amplifiers and found the change to not make a difference. But let's see if the results are different this time.

View attachment 436787
The Douk A5 makes this job both easy and hard. It is easy because you can just lift the plexiglass and replace the op-amps. The difficulty was replacing the standard TI NE5532P opamp with the discrete Sonic Imagery Labs as it was too larger to fit in there. I pushed the adjacent caps more than I was comfortable with to get it to fit. Fortunately it worked.

There is a massive cost difference with the stock NE5532P costing US 57 cents in single quantity compared to minimum of $49 I found for the Sonic Imagery 994Enh-Ticha dual opamp. You would need two of them for stereo operation which would represent a premium that matches that of the amplifier itself! Here is a close up shot the 994Enh-Ticha:

As you see in the above picture, i decided to replace the right channel (Ch 2 below) and left left channel (Ch 1) the same. That way we can compare the two channels simultaneously under the same environmental situation. Amplifiers are temperature sensitive and shutting down to replace the opamp and powering back up would have created another variable. Alas, there is also channel to channel variations so the testing is not 100% exact but very close as you see below.

Opamp Rolling Measurements
Here is our usual dashboard:

View attachment 436792
As we see the performance is the same with SINAD which sums noise and distortion. This is of course at one power level so let's sweep the input voltage and measure at all power levels up to clipping:
View attachment 436793
There is the tiniest gap between the two but that may just be variations between channels. Even if it weren't so, it is a miniscule difference.

Maybe the differences becomes more visible if we use other frequencies than 1 kHz represented above:
View attachment 436795

I have zoomed into this graph to make differences larger. Dashed line is the Sonic Imagery discrete op-amp. We see that both at 15 kHz and at less than 500 Hz, the discrete amplifier is actually worse! But again, that could be variations between channels.

I wanted to investigate that a bit more so ran a couple of FFTs at both 100 Hz and 1 kHz:
View attachment 436797




View attachment 436798
The profile of distortion changes but not the high-order message that any difference is relegated to high order harmonics that are at or below threshold of hearing.

Discussion And Conclusions
It is natural to assume that the much more expensive, larger and fancier hand-made opamp IC would do better. All is not as it seems. An integrated circuit (IC) benefits from high precision components and even components that cannot be instantiated using discrete parts. Path lengths are also shorter allowing for better optimization of the design. Mass production using automated systems follows up by sharply reducing its cost.

On the other hand ICs can be subject to thermal coupling where rise in temperature in one part of the IC can negatively impact the performance of the rest of the IC. This doesn't apply here because the opamp is used at the front-end of the amplifier that is not attempting to produce power (only acts as a buffer and/or gain stage). Importantly, there is feedback that is used to correct the non-linearities in the op-amp. This correction highly linearizes both discrete and integrated op-amps as to almost erase any signature of the original part. This is why we don't see much difference in measurements.

People report improvements in sound and with it justify the upgrade. As members of this forum well know, such listening tests are improper. Testing must be controlled to exclude all extraneous (non audible) factors. When done, the measurements powerfully predict no audible difference. Indeed, I only know of one research paper that dug into sonic differences in op-amps and that only happened when the opamp was vastly overdriven.

Finally, I am not saying that all opamps are the same. There are countless ones for a reason. But unless you have instrumentation such as I am using, you have no prayer of knowing if a change improves anything. Or worse yet, made things worse. Here are the results form the DAC test:

There we do see a bit of differentiation but not enough to bother with any of this.

Net, net, leave the engineering to well, engineers! But a performant audio product and use it as is. Don't risk damaging and spend money on something that has essentially no chance of doing you any good.

Video version available as well:

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Nice take down I would be interested in seeing if you had done the intermodulation distortion test - if it revealed any bigger difference because of the more complex tone layout

 

[wwenze]

Y'know, this gives me an idea

Find the best DAC or amp. Must be 120dB SINAD

And put the 994Enh-Ticha in it.

Watch the external-linked traffic afterwards.

 

[Postlan]

The results of this test were entirely expected, and the same outcome has already been observed in many previous tests. Nevertheless, many audiophiles and equipment designers still claim that they can hear differences in sound quality between op-amps in blind tests. The next step should be to conduct a rigorous ABX test to determine whether the differences that cannot be measured by instruments are truly perceptible to humans.

 

[DavidEdwinAston]

Op-amps swapping is like taking third world medicine

You're lucky if nothing happen

That is brilliant wwenze!

 

[Old_School_Brad]

Since op-amps are often described and advertised using terms similar to EQ, wouldn't it have been more effective to make the point by showing and comparing the frequency response for each swap?

 

[T&T]

Just get 2 monoblocks and replace only in 1 monoblocks the opamps, them raise the volume attenuator back and forth you will hear the difference....sometimes don't make any difference and sometimes will be worse and sometimes you will love it.

I get the measurements but a little bit difference in all frequency at the end will sound different

 

[solderdude]

Just get 2 monoblocks and replace only in 1 monoblocks the opamps, them raise the volume attenuator back and forth you will hear the difference....sometimes don't make any difference and sometimes will be worse and sometimes you will love it.

I get the measurements but a little bit difference in all frequency at the end will sound different

does not work that way. Differences in FR have to be quite measurable before they become audible. Opamps in low gain will never reach audible limits in FR.

 

[Miser_Audioman]

I am completely sympathetic to Amir and other engineers having to go over this again and again. If it is any consolation, this conversation won me over and I changed my vote. What brought me around is the callout ‘hey, were electrical engineers dammit, we might actually know more than amateurs’. Indeed, that hit home to me as a scientist, as a geologist and soil scientist I have amateurs contributing nonsense all the time. Occasionally though an outside perspective does spark progress…

Ironically, i just swapped Sparkos into my V3 monos (sorry Dylan, I am cheap and Amir’s review was favorable. Ill upgrade in your direction eventually…). So on my favorite track the imaging was clearly better. Why? Well likely my favorite volume setting is now a little louder, close to whatever the sweet-spot is for my room. So I paid 150 dollars for a moment of better listening concentration and a lesson in volume optimization.. ah well it was fun anyway..

 

[Quazar]

It is also my question. You all keep saying soundstage has widened, deepened, etc. You say this with every upgrade. How can the soundstage become wider and deeper constantly? Why isn't there a limit to it? You get a new DAC and soundstage expands. You get an amp and soundstage expands. You get new cables and soundstage expands. You put the devices on a stand and soundstage expands. You get AC conditioner and soundstage expands. I am asking how you are measuring this. It is a 3-D space thing, right? How do you know the actual size as to now it being larger?

The universe is expanding, so the soundstage is expanding...

 

[Multicore]

The results of this test were entirely expected, and the same outcome has already been observed in many previous tests. Nevertheless, many audiophiles and equipment designers still claim that they can hear differences in sound quality between op-amps in blind tests. The next step should be to conduct a rigorous ABX test to determine whether the differences that cannot be measured by instruments are truly perceptible to humans.

I don't think so.

(I'm going to use an us vs. them categorical model that I just yesterday deplored in another thread but it's useful here. I am sorry for this.)

We (those who understand physics, measurements, statistics...) are satisfied with the objective information available. Some people (they) insist this information must be incomplete because they can hear something we can't measure. Whose job is it to settle this?

If we do the work and present psycho-acoustic measurements that show with controlled tests the entirely expected results, do you think it would change anyone's position? Maybe a few fence-sitting consumers but the industry that makes its living from conjuring an esoteric aura around the equipment they sell? I don't think so.

I think it is their job to do the work and present measurements that support their claims that we are wrong. But I don't think that's gonna happen.

We've been through all this before with cables. The situation is clear and also stable. No amount of bench or psycho-acoustic measurement is going to change it.

Sometimes I think we all (and here I mean both sides of the us vs them) keep on with these arguments despite knowing that nothing much changes because participating in the arguments is intrinsically rewarding (@Thomas Savage c.f. schismogenesis).

 

[JSmith]

this conversation won me over

JSmith

 

[Multicore]

I am completely sympathetic to Amir and other engineers having to go over this again and again. If it is any consolation, this conversation won me over and I changed my vote. What brought me around is the callout ‘hey, were electrical engineers dammit, we might actually know more than amateurs’. Indeed, that hit home to me as a scientist, as a geologist and soil scientist I have amateurs contributing nonsense all the time. Occasionally though an outside perspective does spark progress…

Ironically, i just swapped Sparkos into my V3 monos (sorry Dylan, I am cheap and Amir’s review was favorable. Ill upgrade in your direction eventually…). So on my favorite track the imaging was clearly better. Why? Well likely my favorite volume setting is now a little louder, close to whatever the sweet-spot is for my room. So I paid 150 dollars for a moment of better listening concentration and a lesson in volume optimization.. ah well it was fun anyway..

Oh, this is encouraging and contradicts my cynical post just above.

Thanks for sharing.

 

[BDWoody]

If it is any consolation, this conversation won me over and I changed my vote. What brought me around is the callout ‘hey, were electrical engineers dammit, we might actually know more than amateurs’. Indeed, that hit home to me as a scientist, as a geologist and soil scientist I have amateurs contributing nonsense all the time.

It's easy to forget that these threads get thousands of views. Check how many visitors are online at any given time. Even if we can't 'get through' to many of those making the arguments, we can still provide the information for those who are able to follow along and have their own light bulb moments.

You never know who is going to have enough of the individual pieces come together where they can get a glimpse of the bigger picture.

For you, if that was this thread, then mission accomplished.

 

[dark132]

If you close your eyes and listen to different operational amplifier ICs, you can hear the difference in very familiar music, but it is only a difference. Psychologically, the more expensive the product, the better it is. So emotionally, the difference becomes a better feeling. But from a scientific point of view, better can only be proved by measurement, and ordinary enthusiasts do not have this condition.

 

[SIY]

If you close your eyes and listen to different operational amplifier ICs, you can hear the difference in very familiar music

Where has this been demonstrated?

 

[dark132]

The results of this test were entirely expected, and the same outcome has already been observed in many previous tests. Nevertheless, many audiophiles and equipment designers still claim that they can hear differences in sound quality between op-amps in blind tests. The next step should be to conduct a rigorous ABX test to determine whether the differences that cannot be measured by instruments are truly perceptible to humans.

The characteristics of some specific ICs are very easy to distinguish, especially the headphone system. I have done an experiment at home, AB comparison in a pure black environment, the same song was played back 30 times, and the recognition ratio was 25:5. It is very simple to identify it by the sound field size.

 

[Hipster Doofus]

From the great Marsuo Basho…1644-1694

In silence they blend,
Voltage whispers in circuits,
Amplified currents.

Feedback loops entwined,
Infinite gain in twilight,
Signals dance in light.

Transistors engaged,
Op amps heart beats pulse and flow,
Nature’s math unfolds.

 

[jan.didden]

On the other hand ICs can be subject to thermal coupling where rise in temperature in one part of the IC can negatively impact the performance of the rest of the IC.

Actually, IC opamps have definitely an edge here. Input, gain and output stages on an IC chip are routinely positioned to minimize thermal drift. For instances, the pos output stage is often positioned in the 45 degrees opposite corner to the related input stage and vice versa, a 'cross coupled' layout, so thermal drifts cancel. You can't get that accurate thermal stability with a discrete design simply because of size.

Also a question: in the very first FFT, which is the red curve?

Jan