Op Amp Replaced: Fosi V3 Monoblocks LM4562NA/NOPB $8x3

[jmdesignz2]

Nice list. But unfortunately an LM4562 vs. an NE5532 doesn't belong on it. Or any other properly applied OpAmp, just not. Here are a bunch rolled for comparison:
View attachment 476265

Even the OPA2604, which makes many OpAmp rollers happy, isn't audibly bad despite having worse distortion. Even the OPA2228, oscillating away in this application , isn't audibly different despite the elevated noise.

For sure they are technically distinguishable compared to each other, I just did above. But unlike your list of different sounds that we all can trivially identify, OpAmps don't have a sound as you imagine and claim to experience.

I'm not clear what the list of different sounds is supposed to mean. Are you implying the people you are posting to can't tell the basic differences between sounds? I am pretty sure even people with zero interest in music or audio can tell. So definite no to any argument that combines appeal to authority and condescension. Or maybe it's a crazy like fox argument, in which case distraction. Perhaps you can explain the relevance to what we can measure and what we can actually hear.

No appeal to authority or condescension lol

a string pluck can sound like metal or nylon. But a poor reproduction will make it hard to hear a difference

 

[jmdesignz2]

So you don't know either SNR.

Have you considered how to test your new op amp to make sure your seller didn't send you something defective?

Of course not lol, I said so at the beginning of this post. That’s why I’m welcoming a test.

Which seller are you referring to? Either way these amps in stock form compare well to my McCormack DNA1 mono blocks and in some ways seem better at my normal listening levels

 

[MAB]

No appeal to authority or condescension lol

a string pluck can sound like metal or nylon. But a poor reproduction will make it hard to hear a difference

Yes, these things sound different in real life, produce different recordings too. Really poor preproduction will make it difficult to hear the timbre of a recorded instrument. The thing is, even the worst OpAmps in the above test aren't audibly distorting, not even the OPA2228 which is not really suited for the circuit I tested it in. The difference between a LM4562 and any other OpAmp in the test is on the order of a few parts per million. Our ears are incredibly insensitive to this amount of distortion. You should be thankful, if we had hearing that was this physically sensitive, the world around us would be deafening. All manner of environmental noises would interfere with your daily life. I think the enhanced sensitivity to distortion would be extremely distracting too, if you could get over the cacophony.

Years ago, I started seeing if I could tell all of these perceived differences. For sure, I thought I had super hearing, and I thought I could hear differences among different implementations. After some time, I realized I couldn't. And nobody I knew could. As I built and bought more things, and measured them, I got to see what does make a difference. Things like the resistance values of the feedback loop make a difference. For some of the more esoteric OpAmps, the grounding and decoupling makes a difference. For some ultra-high-speed devices, all of the above plus limiting the bandwidth and/or gain to a very narrow range makes a difference.

So, how come I don't see people rolling feedback resistors?

But seriously, if you were able to test a LM4562 compared to any number of alternative OpAmps like an OPA2134, or a NE5532, you won't hear a difference. Level-matched, not made to drive some corner-case load, i.e. a fair comparison.

 

[solderdude]

Before would be around what Amir measured for the stock unit

After would be Closer to the theoretical optimum of the TPA amp IC

The TPA3255 is magnitudes worse than both the NE5532, Sparkos and LM4562 so no.... it really cannot get better than the TPA3255 which basically is THE bottleneck in performance.

I didn’t see the scientific rationale for only replacing one of the stock op amps in the ASR test of this Fosi monoblock

The rationale was the recommendation by Fosi.

Besides ... even if the 2nd op-amp that was not replaced was just one half of the balanced signal and performance somehow increased through the presence of another op-amp there should STILL be a measurable improvement. There isn't any.
The 3rd op-amp (unbal->bal) you replaced isn't even in use when using balanced input.

Have you seen the testing done by @MAB and @pma ?
These measurements do not have the 'handicap' of the TPA3255 which determines the measured and sonic performance.

AFAIK it runs on a balanced signal and swapping only one seems unscientific

it only seems that way.
The TPA3255 is the limiting factor in ALL measured aspects.

That’s why I’m welcoming a test.

Then YOU either DO a PROPER test yourself (blind, level matched, witnessed, statistic relevant and checked for operation) or you make use of proper tests that have been done.
Your subjective findings are not admissible as 'proof' I'm afraid.

Of course... alternatively ... you can trust your hearing and those of other 'op-amp swappers' (there are soooo many of them) and stop trying to convince ASR members that your hearing is trustworthy and we must believe you.
There is no objective evidence on your side nor is there any rationale on your side. Only your subjective observation.

You do realize that the frequency response (as well as distortion) in the higher frequencies are limited by the TPA3255 and the NE5532 and LM4562 both are magnitudes 'better' than that of the TPA3255 (and its output filter) which both have nothing to do with PSSR of op-amps either.

 

[voodooless]

Well. Due to ASR my expectations were tempered so I spent a tiny fraction ($8x3) and didn’t expect anything to be different.

Except you do:

Before would be around what Amir measured for the stock unit

After would be Closer to the theoretical optimum of the TPA amp IC

Can one tell the difference between a violin and a cello?

Plastic vs paper vs metal being struck by a finger vs wood vs metal tool?

How about a tambourine vs a chime? How about palm strike vs finger.

The resonant signature of a toy piano vs baby grand.

Individual seeds in a shaker/maracas, varying with varying degrees of arm movement and intensity

All of this I can distinguish on a cheap Bluetooth speaker. I don't need a fancy opamp for that.

 

[solderdude]

I’m using to subjectively evaluate them and I’m hearing some obvious differences especially in the higher frequency instruments sounding more true, texture and nuance

But it didn’t sound worse and heard a few very subtle differences in my system on tracks I’ve listened to for over 10 years

So a few very subtle but obvious differences ?

 

[voodooless]

So a few very subtle but obvious differences ?

It was obviously very subtle

 

[RandomEar]

What you are saying is all scientifically correct

However misses the point of what I’m describing as the differences I’m experiencing

No, it doesn't miss the point, that's the whole point. Your brain is almost certainly interpreting differences into the comparison which do not exist. That was the whole point I was making with that post and it still stands.

Can one tell the difference between a violin and a cello?

Plastic vs paper vs metal being struck by a finger vs wood vs metal tool?

How about a tambourine vs a chime? How about palm strike vs finger.

The resonant signature of a toy piano vs baby grand.

Individual seeds in a shaker/maracas, varying with varying degrees of arm movement and intensity

Apples and oranges. Your examples aren't small differences. Swapping opamps in your device results in differences barely large enough to measure, they may even measure identical at the speaker outlets. These differences are so incredibly small, our ears wouldn't be able to discern them anyway. All the differences you think to hear are the result of your human brain playing tricks in you. It's normal and happens to everyone.

Unless you provide any evidence of the contrary, this is the most plausible assumption.

 

[solderdude]

Knowing there are 'incredibly high spec' op-amps in there is all one needs to 'hear' subtle but obvious differences.
Even when you don't expect to hear differences.

 

[Sokel]

Knowing there are 'incredibly high spec' op-amps in there is all one needs to 'hear' subtle but obvious differences.
Even when you don't expect to hear differences.

That's if you choose to forget TPA3255 who will nicely iron everything to its own no giving a damn about the op-amp niceness.

Can't help it, even I will use car analogy here (I'm extremely sorry folks, must be my second ever)

So, what good is a 500hp engine in a car trapped in container?
That's the idea.

 

[Multicore]

Of course not lol, I said so at the beginning of this post. That’s why I’m welcoming a test.

You can and should do this test yourself. It's the best way. Do what solderdude said before.

Please record the output of the amp (with speakers connected) in 24/192 (or at least 24/96) format of the part in the music where you clearly hear differences.
No microphones nor speakers ... simply record the output directly and post those files.

I like this proposal. I want to hear the differences that @jmdesignz2 can hear. And then we can analyze the files to find the corresponding signal differences.

If the amps are sent somewhere else for test it won't be the same and there will be room for doubts.

 

[aon500]

Try cheap discrete opamp , you won't regret spending the money.

 

[voodooless]

Try cheap discrete opamp , you won't regret spending the money.

Why not?

 

[NTK]

Try cheap discrete opamp , you won't regret spending the money.

Why not?

Especially given that the AliExpress page says this:

 

[aon500]

Sorry I just want to suggest cheap discrete opamp to @jmdesignz2 .

I know this SX52B not work for Fosi , AK05 Akliam is good too but I don't have a pic.

And don't waste your time explain about op amp can make a differences here.

 

[HalSF]

Could have been spared this torrent of verbiage and exasperation by posting this op-amp rolling victory at the Steve Hoffman Audio Hardware forum, and been celebrated as a cutting-edge hero of the “hobby.”

 

[voodooless]

And don't waste your time explain about op amp can make a differences here.

If you actually have something valuable to add, then post it.

 

[MAB]

I know this SX52B not work for Fosi

So can I get this straight... You were purposely giving incorrect advice, telling someone to buy an incompatible OpAmp that you knew wouldn't work for their application?

If so, you are being really irresponsible, even cruel.
At best it doesn't work and you cause the person to waste money.
At worst, it damages the gear. Even worse, but unlikely, causes injury.
These are electrical devices, we already have enough know-nothings around here without some miscreant trying to undermine them further.

Like apologize for being a jerk since your suggestion is uninformed, or provide clarity on what you really intended for the person to do.

 

[solderdude]

That recommendation is pointless because:
There is no data sheet verified by independent testers nor at TI level.

If you really want to hear a difference try a 'mono to dual op-amp converter' and use 2x OP07 (or when you want TI documentation the uA741).

 

[jmdesignz2]

Nice list. But unfortunately an LM4562 vs. an NE5532 doesn't belong on it. Or any other properly applied OpAmp, just not. Here are a bunch rolled for comparison:
View attachment 476265

Even the OPA2604, which makes many OpAmp rollers happy, isn't audibly bad despite having worse distortion. Even the OPA2228, oscillating away in this application , isn't audibly different despite the elevated noise.

For sure they are technically distinguishable compared to each other, I just did above. But unlike your list of different sounds that we all can trivially identify, OpAmps don't have a sound as you imagine and claim to experience.

I'm not clear what the list of different sounds is supposed to mean. Are you implying the people you are posting to can't tell the basic differences between sounds? I am pretty sure even people with zero interest in music or audio can tell. So definite no to any argument that combines appeal to authority and condescension. Or maybe it's a crazy like fox argument, in which case distraction. Perhaps you can explain the relevance to what we can measure and what we can actually hear.

Apologies, I was not more clear-

My examples weren't intended to be analogies of scale
The argument is not that an OpAmp changes the sound as dramatically as a violin changes from a cello, but that a change in a critical electrical component is a change to the signal chain

A better example would be hearing more of a difference in the nuances of the seeds in a maraca or more difference in emphasis/attack, hearing a more nuanced finger vs palm movement on a drum skin. Hearing more nuance in the texture of a drum skin etc.

While the resulting sonic differences are subtle and don't make the sound a 'new instrument,' they change its character, texture, and resonance, which are all perceived by the human ear. The fact that these changes are not as easily charted by a simple measurement doesn't make them inaudible to a trained listener