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Op-amp Rolling Using Sparkos on Fosi V3 Mono

Rate this opamp rolling study:

  • 1. Poor (headless panther)

    Votes: 12 6.3%

  • 2. Not terrible (postman panther)

    Votes: 10 5.3%

  • 3. Fine (happy panther)

    Votes: 19 10.0%

  • 4. Great (golfing panther)

    Votes: 149 78.4%
  • Total voters
    190
olds1959special said:
I must have golden ears, I heard a little difference from NE5532 to LM4562.
Click to expand...
Try it controlled - level matched and blind.

Or, to put it another way.

What you heard didn't come from the sound waves reaching your ears - it was created in the wetware between them.
 
olds1959special said:
I consider op-amp rolling like adding sauce to your food. It won't make a major difference to the nutritional value, but it might add a little flavor you like.
Click to expand...
more like a mime pressing his hands on an imaginary wall lmao
It might appear like he’s pushing up against a solid object but he’s just pretending
 
After all the options and and gold plated tin ears have had their say this all is still a bit silly.



Take a look at @amirm 's dashboard from his Fosi V3 review. The SINAD is 100.27dB (pretty darn good, I would say)

Below that is a FFT plot of of a OPA1656 installed in a Neurochrome HP-22 PCB. The SINAD is 20dB's better than (pretty darn good). *

1777847025169.png




1777847470074.png


* The HP-22 PCB is the circuit tool I use to evaluate Op-Amps.

Thanks DT
 
Yeah i'm with you , but we need to acknowledge that the swapping guys don't hear anything, they just believe in a tweak because they changed something...they have no clue about circuitry
 
Gremlins said:
Yeah i'm with you , but we need to acknowledge that the swapping guys don't hear anything, they just believe in a tweak because they changed something...they have no clue about circuitry
Click to expand...
Right, but there are circuits which are compatible with both. I just don't believe that there are speakers with enough resolution to hear the difference because it is so small. Once you understand the dynamics of the circuit itself; the improvement from a NE5532 to a LM4562 is small and won't be able to be heard in 98% of scenarios (and the last 2% are assuming you have the right resolution headphones and know what you are looking for based on the sonic characteristics of the circuit).
 
amirm said:
This is a study of measured differences if one swaps up the TI NE5532p dual IC op-amp in a Fosi V3 Mono amplifier with a "discrete" opamp from Sparkos. It is a test requested in the youtube comments of my video test of the same using Douk A5 and Sonic Imagery op-amp. The Sparkos SS3602 retails for US $79.80 but I found a discount coupon that brought the cost down to $74.33 with shipping included.
View attachment 441085

Per Fosi documentation, there are three op-amps. The one at the bottom is only for unbalanced/balanced conversion. That leaves two op-amps to swap. Company says if you have only one, to change the #2, middle right to impact the tonality. So that is what I did as you see in the above picture. For clarity, this is a mono amplifier so the two ICs are dedicated to the same channel.

The Fosi V3 Mono with its balanced input was quite stable in operation, allowing me to borrow some of my review measurements. I did however repeat a couple as well (which confirmed the same).

In this second assessment of opamp rolling, I tried to address some of the criticism of the last test as you see below. Hopefully it completes a picture as this is the forth or fifth such testing.

Sparkos SS3306 Opamp and Fosi V3 Measurements
For my first test, I ran a full power sweep with the stock NE5532p and then with SS306. This allows us to see the noise+distortion at all power levels, accomplishing a number of things at once:
View attachment 441086
As we see, the results (subject to run to run variation) is essentially identical. Performance is most likely dominated by the class D output stage, not the input buffer/gain stage.

Question was asked about frequency response, thinking that explains some of the perception of tonality difference in uncontrolled, subjective evaluations. Here is that:
View attachment 441088

Again, it is the output class D amplifier IC which generates this response, not the front-end op-amps. The latter likely has much flatter and wider response. With identical frequency response, no tonality difference can be explained or justified.

A common retort was running only "static" tests. Never mind that a sine wave is not a static signal but time varying by a mathematical formula. Regular readers of ASR know that we have a good stand in, in the form of 32-tone test signal. Most have seen those 32 spikes in frequency domain but not that many know what it looks like in time domain: the thing that the amplifier "sees:"

View attachment 441089

Let's agree that this is a highly complex signal. Not only that, it has ton more energy in higher frequencies than real music, with full amplitude tones going to 20 kHz. Any worry about "slew rate" then would be tested here. Let's overlay the stock 5532 opamp and Sparkos Labs SS3602:
View attachment 441090
The response is again, identical. Yes, there are individual noise/distortion spikes that are a hair different but they won't amount to anything and certainly won't explain any perceived audio difference.

Another question was that of ultrasonics and worries of oscillations. My audio analyzer has a bandwidth of 1 MHz so I tested that far:

View attachment 441091
I forgot to take out my high-resolution AES-17 filter so the energy is brought down gradually from 40 kHz on. Since both measurements are impacted the same way, we can still compare. Once more, we see no meaningful difference.

Discussion and Conclusions
All of this came about because I predicted and promised that op-amp swapping won't make a difference when I tested the Douk A5 amplifier. How did I know that? For the following reasons:

1. The op-amp stage uses a ton of feedback. Since they have an easy time versus the amplifier output stage, it is trivial to get this pre-amp portion to far exceed the performance that is needed in terms of noise, distortion and bandwidth.

2. Some replacement op-amps may be designed as to produce better performance. But that requires circuit modification (e.g. to change level of feedback). Without it, you won't see that impact.

3. Turns out the NE5532p, despite its age, is an excellent opamp for audio applications. While there are thousand of opamps out there, they are solving different problems than the plain application we have.

As to outcomes of different sound people hear in swapping op-amps, basic science of controlled testing says a) these tests have to be fully controlled (blind, level matched) and b) run instantaneously. You can't listen to an amp, tear it down, put in a different opamp and expect to have any kind of valid test. Our knowledge of engineering, confirmed by measurements and science of psychoacoustics says there is no audible difference.

Note that mistakes can be made that do cause audible differences. If the new opamp causes oscillation for example, that could be audible. If you change volume, as a pair of youtubers did, of course you can perceive a difference. So it is not that it is impossible to hear something. It is that you need to do your homework in any such swaps and very preferably, measure to see what has happened. This rules out any audiophile testing, no matter how golden you think your ears are.

Finally, our instrumentation as always is exceedingly accurate, able to dig way, way below threshold of hearing to find differences. So it is not that our measurements are blind to differences. They are not. We can see and evaluate the changes and confidently confirm lack of audibility in such swaps.

As to Sparkos SS3602, it works and doesn't harm anything. But doesn't improve your amplifier either for reasons stated above.

-----------
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/
Click to expand...
The measurements do indeed look identical. And the things you say about doing a double blind listening with the ability to immidiately do the switch between two level adjusted amps with different op amps deemed mandatory for most.
But.
There exist a certain YT clip where a Fosi ZA3 with the standard op amps and another ZA3 with Sparkoss op amps. If that is anything to go by and we presume everything is done by the book. You can easily hear a difference between the two. With differences to clarity especially in the mids and differences cleraly heard on somerhing like reverb. The vid contains several different genres and sound bits with the differences between the two being consistent and constantly in favor of the Sparkoss.
Anyone know this clip and can vouch for its quality/ relevance?
 
Don't forget, that all this has to be done in an unsighted surrounding, where one never knows, what is currently been running and what is expected from a sighted seeing. Don't forget, that switch has to be done "instantaneously" because human audio memory will only last a few seconds...
This needs a lot of preparation to obey to the point. Most just "listen" and don't care about all those preparations, which produces then - obviously - "expectation bias".... with known results.
 
rappaport said:
The measurements do indeed look identical. And the things you say about doing a double blind listening with the ability to immidiately do the switch between two level adjusted amps with different op amps deemed mandatory for most.
But.
There exist a certain YT clip where a Fosi ZA3 with the standard op amps and another ZA3 with Sparkoss op amps. If that is anything to go by and we presume everything is done by the book. You can easily hear a difference between the two. With differences to clarity especially in the mids and differences cleraly heard on somerhing like reverb. The vid contains several different genres and sound bits with the differences between the two being consistent and constantly in favor of the Sparkoss.
Anyone know this clip and can vouch for its quality/ relevance?
Click to expand...
I, too, can vouch for irrelevance of audio comparisons using YouTube. Think about the signal chain for two seconds:
  • Their source with their settings (possible EQ/DSP, etc.)
  • Their DAC with their settings
  • Their amp
  • Their speakers + their room
  • Their microphone + ADC
  • Their capture device with their settings
  • Their post processing & video production workflow
  • YouTube compression
  • Your source with your settings
  • Your DAC
  • Your amp
  • Your speakers + room or your headphone
Almost any change along a point in this chain will alter the sound. The most problematic points are in the hands of the dude producing the video, who only makes money if enough people watch it. If any settings change on their side - knowingly or unknowingly - the comparison is skewed. That is disregarding the problems of testing sighted and without quick switching on the viewers side.

Op amps have slightly different gain and the volume level wasn't matched? Ruined comparison. Touched the mic cable between runs, causing a 5° change in alignment? Ruined comparison. Moved some chairs around or opened the blinds, changing the reflectionsbin the room? Ruined comparison. I think you get where I'm going with this.

YouTube videos are never a valid form of comparison for audio devices.
 
He's got 11 posts on the forum, and it's a clean sweep...
Here's one, these guys all seem to have the same kind of profile.
Post in thread 'SMSL PL200T Review (CD Transport)'
www.audiosciencereview.com

SMSL PL200T Review (CD Transport)

I'm the opposite. I don't know why I wasted so many years ripping all my CDs via EAC to the NAS. I just prefer the simplicity of popping a CD in and enjoying it from beginning to end. It just works. Nothing to boot, connect, no bloody Raspberry Pi, no ugly boxes and tiny cables, no silly...
www.audiosciencereview.com www.audiosciencereview.com
They all work for the best brands, lean on research from the best universities, they all have the best big beautiful kind of personality if you see what I mean.
 
Karmacoma said:
He's got 11 posts on the forum, and it's a clean sweep...
Here's one, these guys all seem to have the same kind of profile.
Post in thread 'SMSL PL200T Review (CD Transport)'
www.audiosciencereview.com

SMSL PL200T Review (CD Transport)

I'm the opposite. I don't know why I wasted so many years ripping all my CDs via EAC to the NAS. I just prefer the simplicity of popping a CD in and enjoying it from beginning to end. It just works. Nothing to boot, connect, no bloody Raspberry Pi, no ugly boxes and tiny cables, no silly...
www.audiosciencereview.com www.audiosciencereview.com
They all work for the best brands, lean on research from the best universities, they all have the best big beautiful kind of personality if you see what I mean.
Click to expand...

Just look at his debut post. Hell of a way to announce yourself.
 
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