Fosi Audio V3 op-amp rolling, has anyone tried it? Snake oil? Or are there actual differences?

[Agapit68]

In class A, AB, G and H there is no fast switching involved and usually one can get by with smoothing caps and the occasional decoupling near the power and/or voltage amplification stage to prevent instability.

For switching amps just having large electrolytics isn't enough because these may (PCB) design wise too far away from the power-switching devices. Even 10cm distance can be problematic due to the inductance of the traces/wires. Certainly if the device also has to comply to EMC/FCC rules.
A small capacitor parallel on those reservoir caps won't do anything up to say a MHz or so but can help in the 10Mz-10GHz range at the point where the switching power devices are located.
Small capacitors need to be charged/discharged quickly and with sharp rising/falling edges requiring high (narrow=HF) frequencies far, far above the switching frequency.
This requires local decoupling and (for RF) further removed caps like reservoir caps the inductance simply is too high so decoupling away from the switching components that draw the current peaks decoupling there will do nothing beneficial for the amp itself.
For that reason the decoupling needs to be done near the switching devices directly to a groundplane with as short as possible wires.
Compound is often needed using 10uF and 100nF or so (or something smaller) and need to be small in size. Larger sized caps (think WIMA) have too high ESR at GHz range.
Where you do see those used is at the output filter because of the large voltage swing across it where CML are poor performers.
At a constant voltage (power rail decoupling) the CML ones perform better than WIMA.

It is the 'audiophool myth' world that made the WIMA big in analog amps because they supposedly 'sound' better than other PP caps.

So while you may hear improvements and magic decoupling reservoir caps it won't do much (if anything) for the decoupling of the output devices as that has to be (and probably even is for cheaper designs) done locally near the output devices.

You need to measure in the GHz range to show these effects and is mostly about emission of RF that has to meet requirements and the output stage being fed from a low impedance voltage rail exactly at the pins of the powerIC/switching devices. Not at the reservoir caps.

Thank you for the detailed answer! The statement that it "does nothing" or is a "psychological effect", "placebo", etc. certainly takes place, but remains an assumption, especially in my case - I do not like this amplifier and I am not inclined to endow it with magical properties). For me, it is obvious that the sound has changed for the better, as it seems to me at first glance, but of course, these may simply be distortions that are pleasant to my ears and without measurements there are no other ways to find out. On the other hand, I am ready to put up with additional distortions (within reasonable limits) for the sake of, for example, improving the rise time/slew rate.

 

[antcollinet]

I do not like this amplifier and I am not inclined to endow it with magical properties)

That is not how perceptive bias works. It has nothing to do with your conscious biases (prejudices) or expectations:

We know that our hearing is subject to cognitive/perceptive bias. What we hear is impacted by what we know, what we believe, how we feel, our life experiences, what we see etc etc. No-one is immune to this if they are human - it is how we are built. In fact we would be unable to function if our senses were not filtered by our subconscious brain. Everyone is subject to this, it happens at the subconscious level, and it is not possible to avoid it - even when we are aware it is happening.

Put it simply - if you are listening sighted, and hearing differences where none would be expected, it is almost certain those differences are not in the sound reaching your ears, but are being created in the wetware between them.

 

[solderdude]

these may simply be distortions that are pleasant to my ears.

Highly unlikely that harmonics nor FR has actually changed, let alone in an audible manner.

 

[Agapit68]

Highly unlikely that harmonics nor FR has actually changed, let alone in an audible manner.

But you can't guarantee that?

 

[antcollinet]

But you can't guarantee that?

Put it simply - if you are listening sighted, and hearing differences where none would be expected, it is almost certain those differences are not in the sound reaching your ears, but are being created in the wetware between them.

In other words - in such an unlikely situation - no point making a guess. No meaningful assessment can be made without a controlled blind test. Anything else is of no interest other than to yourself.

 

[solderdude]

But you can't guarantee that?

I would place a bet on it that no discernible measurable differences will be found.

 

[Agapit68]

These are expected comments that I have read on this forum many times already)). However, I am not the only one, not only in this thread, but also in the one where the Fosi V3 is discussed directly, who did not like the HF and MF of this amplifier. That is, strangers from different places, without agreeing with each other, listened to different music in different systems and rooms, at different times of the day, with different moods, but independently of each other formed similar opinions about the Fosi V3. And on the other hand, I see an initiative group here, the members of which are trying to convince all the dissatisfied that it only seems so to them, and everyone else that the dissatisfied can never hear any differences, simply because they should not)) At the same time, a spin begins to discredit the opinions of the dissatisfied, in which the same regulars of this Internet resource participate. And one more important nuance - many posts of the dissatisfied were immediately deleted by moderators during the promotion of the V3. As a result, we have here an organized group of individuals who, by prior agreement, defend the interests of certain companies.

 

[SIY]

These are expected comments that I have read on this forum many times already)). However, I am not the only one, not only in this thread, but also in the one where the Fosi V3 is discussed directly, who did not like the HF and MF of this amplifier. That is, strangers from different places, without agreeing with each other, listened to different music in different systems and rooms, at different times of the day, with different moods, but independently of each other formed similar opinions about the Fosi V3. And on the other hand, I see an initiative group here, the members of which are trying to convince all the dissatisfied that it only seems so to them, and everyone else that the dissatisfied can never hear any differences, simply because they should not)) At the same time, a spin begins to discredit the opinions of the dissatisfied, in which the same regulars of this Internet resource participate. And one more important nuance - many posts of the dissatisfied were immediately deleted by moderators during the promotion of the V3. As a result, we have here an organized group of individuals who, by prior agreement, defend the interests of certain companies.

There's lots of reports of alien abductions with anal probing. That doesn't mean it's true.

 

[Killingbeans]

But you can't guarantee that?

No. But we also can't guarantee that you won't win the lottery 17 times in row.

Sometimes you just gotta let go of the dream

 

[antcollinet]

many posts of the dissatisfied were immediately deleted by moderators during the promotion of the V3. As a result, we have here an organized group of individuals who, by prior agreement, defend the interests of certain companies.

That is quite an accusation. I think you need to provide evidence of that or withdraw your statement.

The only time posts are deleted here are when they flout the rules of engagement. Even when a poster gets a thread ban, posts are rarely if ever deleted. And posts are never deleted for criticising the performance of a particular piece of gear unless actually defamatory, nor to "defend the interests of certain companies."

Further:

These are expected comments that I have read on this forum many times already)). However, I am not the only one, not only in this thread, but also in the one where the Fosi V3 is discussed directly, who did not like the HF and MF of this amplifier.

This is not what we have been talking about here. We have been discussing the audibility of adding a random capacitor to the bulk electrolytics. Trying to apply comments about that to a completely different phenomena is just dishonest.

 

[Killingbeans]

That is, strangers from different places, without agreeing with each other, listened to different music in different systems and rooms, at different times of the day, with different moods, but independently of each other formed similar opinions about the Fosi V3.

There's a lot of myths surrounding small Class D amplifiers. Some of them are sure to invade most people's minds.

This particular amp also does not include the output filter in the feedback loop. You could argue that it maybe gives a slightly elevated treble responses from most speakers. This is of course pure speculation, but maybe it would explain the unfavorable reports. Most likely it doesn't though.

In any case, putting Wimas in parallel with the PSU caps definitely won't change a thing.

 

[MaxwellsEq]

These are expected comments that I have read on this forum many times already)). However, I am not the only one, not only in this thread, but also in the one where the Fosi V3 is discussed directly, who did not like the HF and MF of this amplifier. That is, strangers from different places, without agreeing with each other, listened to different music in different systems and rooms, at different times of the day, with different moods, but independently of each other formed similar opinions about the Fosi V3. And on the other hand, I see an initiative group here, the members of which are trying to convince all the dissatisfied that it only seems so to them, and everyone else that the dissatisfied can never hear any differences, simply because they should not)) At the same time, a spin begins to discredit the opinions of the dissatisfied, in which the same regulars of this Internet resource participate. And one more important nuance - many posts of the dissatisfied were immediately deleted by moderators during the promotion of the V3. As a result, we have here an organized group of individuals who, by prior agreement, defend the interests of certain companies.

YOU are making a claim It's YOUR task to prove you are right.

1) Measure it when it's unchanged, (amplitude, noise, distortion, multitone, gain-linearity).
2) Make the change
3) Measure it after it's unchanged, (amplitude, noise, distortion, multitone, gain-linearity).

Post the results here.

 

[Agapit68]

There's lots of reports of alien abductions with anal probing. That doesn't mean it's true.

163 / 5 000

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You have a wide range of interests! Where do you get your information? I hope you explained to them all that only blind tests of butt plugs can establish the truth?

 

[BDWoody]

163 / 5 000

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You have a wide range of interests! Where do you get your information? I hope you explained to them all that only blind tests of butt plugs can establish the truth?

You mean we need evidence? Yes, that's what is always missing.

Why not try to create/provide actual evidence to demonstrate how wrong everyone here is, rather than try to disparage our membership?

Making empty claims is easy...

 

[Down South]

YOU are making a claim It's YOUR task to prove you are right.

1) Measure it when it's unchanged, (amplitude, noise, distortion, multitone, gain-linearity).
2) Make the change
3) Measure it after it's unchanged, (amplitude, noise, distortion, multitone, gain-linearity).

Post the results here.

As always what is missing is - the listening tests. What individual people hear - is what they hear. To insult what people hear and tell them they are deluded etc. etc. actually says a lot of those who repeatedly make these insulting comments. Being profiled individually by an experienced analyst would yield interesting character profiles that they would prefer not to share with the membership of this site.

No one in their right minds would deny that measurements reveal the outcome of the chosen layout and components and the mentality of the teams that created the piece of equipment. The fact remains that the important end point is - does the individual like what they hear. This is as always defined by the sum total of that individual's life experience/cultural brainwashing For some time now a lot of people have damaged the ability of their pathway to hear - their ears, to transmit an accurate route to the brain and it's ability to provide even remotely something resembling the music that entered the aural pathway.

Notwithstanding this, people from very different cultures can and do get off to the same piece of music and that is truly wonderful.

 

[BDWoody]

To insult what people hear and tell them they are deluded etc. etc. actually says a lot of those who repeatedly make these insulting comments.

Where are the insulting comments, other than from you?

Being profiled individually by an experienced analyst would yield interesting character profiles that they would prefer not to share with the membership of this site.

What a ridiculous thing to say. Are you that upset by being challenged?

I thought we were just looking for anything at all that might actually support what he is claiming. Properly controlled listening tests would also be welcome, but for most that is a bridge too far in terms of what they are willing to do. Making measurements of the output can easily show what has changed, and could give a very good clue as to whether/what is audible after whatever changes were made. Without either of those two things, we are left with just more very unlikely claims with zero evidence or data to support it. As usual.

 

[BDWoody]

And one more important nuance - many posts of the dissatisfied were immediately deleted by moderators during the promotion of the V3. As a result, we have here an organized group of individuals who, by prior agreement, defend the interests of certain companies.

Which thread are you talking about? I'll go have a look and see how many posts were deleted and why and let everyone know.

 

[Agapit68]

You mean we need evidence? Yes, that's what is always missing.

Why not try to create/provide actual evidence to demonstrate how wrong everyone here is, rather than try to disparage our membership?

Making empty claims is easy...

I prefer the more casual style of communication set by Fosi themselves, because they don't provide op amp measurements, so why should I behave any differently?

 

[BDWoody]

I prefer the more casual style of communication set by Fosi themselves, because they don't provide op amp measurements, so why should I behave any differently?

They are selling stuff... Are you?

 

[MaxwellsEq]

As always what is missing is - the listening tests. What individual people hear - is what they hear. To insult what people hear and tell them they are deluded etc. etc. actually says a lot of those who repeatedly make these insulting comments. Being profiled individually by an experienced analyst would yield interesting character profiles that they would prefer not to share with the membership of this site.

No one in their right minds would deny that measurements reveal the outcome of the chosen layout and components and the mentality of the teams that created the piece of equipment. The fact remains that the important end point is - does the individual like what they hear. This is as always defined by the sum total of that individual's life experience/cultural brainwashing For some time now a lot of people have damaged the ability of their pathway to hear - their ears, to transmit an accurate route to the brain and it's ability to provide even remotely something resembling the music that entered the aural pathway.

Notwithstanding this, people from very different cultures can and do get off to the same piece of music and that is truly wonderful.

Sure...

But you have missed the point. There is a reference design. People (including @Agapit68 ) are fiddling with the design. I'm an electronic engineer, and this fiddling would normally be considered unsound or (at best) a complete waste of time. But that's entirely up to the fiddlers as long as they have time to spare, don't mind damaging kit, don't burn the house down or interfere with tv and radio signals.

But, these people doing the fiddling also claim there is an improvement in sound quality. Based on their description of the fiddling they are doing, it is electronically unlikely they would be able to hear a difference. If there is a difference it's likely to be increased distortion (which many of us like) or noise.

The two principle ways to identify what's happening are 1) detailed before and after bench tests OR 2) level-matched double-blind listening tests with a range of people with different levels of training on professional audio listening tests. 1) is quick and relatively cheap. That's why I proposed it.

BTW this is nothing to do with people having the freedom to listen how they like, to what they like, using whatever gear they like. I'm all for that. All I asked for was evidence that a change genuinely is beneficial.