Topping B100 Amplifier Review

[Skj]

Is it correct that heavy negative feedback in amps give away fine details? How nested feedback amps like topping b100 are different than forward feedback amps like benchmark ahb2 ? If nested feedback can give such high sinad figures with good power of 200w like in topping b200 at such good price then why at all people should go for class d modules?

 

[Julf]

Is it correct that heavy negative feedback in amps give away fine details?

No. Why would that be? It is one of those silly audiophile myths from 50 years ago that still lives on on audiophool forums.

"The F-word or, why there is no such thing as too much feedback" by Bruno Putzeys

 

[terryforsythe]

No. Why would that be? It is one of those silly audiophile myths from 50 years ago that still lives on on audiophool forums.

Some 40 years ago often it was said that copius amount of negative feedback caused higher levels of IMD. My speculation is that some marketing person came up with that to justify why their product supposedly was better; I have never seen it proven to be the case. Indeed, from the test data I have seen, amplifiers with high levels of feedback have not only lower THD and noise, but also lower IMD.

 

[terryforsythe]

If nested feedback can give such high sinad figures with good power of 200w like in topping b200 at such good price then why at all people should go for class d modules?

It comes down to preference. The B200 sets the bar for SINAD, but at some point the differences become inaudible. For the same price class D amplifiers can provide more power.

I ran an experiment. I have a pair of Topping B100s powering my tweeters. When I put my ear right next to one of my tweeters, I cannot hear any noise. I then connected my Hypex Nilai, which normally powers my woofers, to my tweeters. With the Nilai, I could hear a tiny bit of noise through the tweeter with my ear right next to it. But, the noise was inaudible once I pulled my head back 25cm, and certainly not audible at my listening position. I have both amplifiers set to high gain. At high gain the SINAD of the B100 is 117.6dB, and the SINAD of the Nilai is 104dB.

 

[DavidMcRoy]

Google Dr. Matti Otala’s 1970s work on negative feedback. I have no idea whether I could hear any of the alleged issues. Meanwhile, Purifi stated that Class D circuits do not have a mechanism for the creation of transient intermodulation in the first place. (Transient Intermodulation, or TIM lies at the heart of the issue.)

 

[terryforsythe]

Google Dr. Matti Otala’s 1970s work on negative feedback. I have no idea whether I could hear any of the alleged issues.

I googled it, but did not come accross the original work, but a summary I found indicated that excessive negative feedback can increase TIM, which can occur if the slew rate is slow. Here is what Google AI says about TIM (take it with a grain of salt):

"TIM stands for a specific type of audio distortion that occurs in amplifiers using negative feedback when a fast-changing signal (a "transient," such as a drum hit or guitar Transient Intermodulation Distortion. It ispluck) overloads the input stage.

...

How It is Prevented

To eliminate or mitigate TIM, modern amplifier designers utilize a few key techniques:

• High Slew Rate: Engineers design the amplifier's input and voltage amplification stages to have a very high slew rate (the ability to change voltage rapidly), so it can easily keep up with fast transients. [1, 2, 3, 4, 5]
• Input Low-Pass Filtering: By limiting the bandwidth of the input signal, the rate at which the signal rises is slowed down, preventing the input stage from being overwhelmed. [1, 2]"

I did not see in Topping's specifications what is the slew rate of the B100, but once again according to Google AI (recall the grain of salt thing):

"The Topping B100 features a rated slew rate of ± 350 V/μs. This highly responsive "Diamond Differential" circuitry allows for extremely fast transient recovery and helps to virtually eliminate transient intermodulation distortion (TIM)."

 

[Miercoles2022]

The Ottala TIM argument has been superseded with time and understanding, no? I take it that the whole industry was chasing a red herring at the time.

Bob Cordell articles

Nevertheless, some fabulously built and still good performing amps were produced then.

 

[Julf]

The Ottala TIM argument has been superseded with time and understanding, no? I take it that the whole industry was chasing a red herring at the time.

Yes, as I wrote earlier, it was realized it was just a form of SID, and easily avoided.

I really suggest reading the Puzeys white paper I linked to earlier.

 

[Julf]

Google Dr. Matti Otala’s 1970s work on negative feedback. I have no idea whether I could hear any of the alleged issues.

As someone who studied electrical engineering and audio in Finland in the 1980s I am rather familiar with the work of Matti Otala. He did a lot of valuable work, but in the half-century since we have learned much more about feedback.

 

[EJ3]

I googled it, but did not come accross the original work, but a summary I found indicated that excessive negative feedback can increase TIM, which can occur if the slew rate is slow. Here is what Google AI says about TIM (take it with a grain of salt):

"TIM stands for a specific type of audio distortion that occurs in amplifiers using negative feedback when a fast-changing signal (a "transient," such as a drum hit or guitar Transient Intermodulation Distortion. It ispluck) overloads the input stage.

...

How It is Prevented

To eliminate or mitigate TIM, modern amplifier designers utilize a few key techniques:

• High Slew Rate: Engineers design the amplifier's input and voltage amplification stages to have a very high slew rate (the ability to change voltage rapidly), so it can easily keep up with fast transients. [1, 2, 3, 4, 5]
• Input Low-Pass Filtering: By limiting the bandwidth of the input signal, the rate at which the signal rises is slowed down, preventing the input stage from being overwhelmed. [1, 2]"

I did not see in Topping's specifications what is the slew rate of the B100, but once again according to Google AI (recall the grain of salt thing):

"The Topping B100 features a rated slew rate of ± 350 V/μs. This highly responsive "Diamond Differential" circuitry allows for extremely fast transient recovery and helps to virtually eliminate transient intermodulation distortion (TIM)."

Google does not know ANYTHNG (EXACTLY the SAME as AI). It just collates information. If there is more information saying that something is a problem, then it sways that way, even if the issue was debunked. Particularly after it was debunked. As there is little information from the side that debunked it after it's debunking. But there will still be more information from those that were debunked, trying to say "It ain't so") to those that debunked the BS. And because there is that "after the fact" of the debunking information, it decides to go on that, just because there is more total information in that direction.
Hence, both Google and AI are frequently WRONG but believed by people that don't understand this and hold Google (and/or AI) up on a pedestal of ("because Google [or AI] said it, it must be the case.
This is why one must do their own research and also discover "who is being paid by whom" for these papers.
Even the Universities that get big donations from certain people in certain fields have been (more frequently than most believe) been swayed to approve falsehoods in papers because of the connections of their graduate that is making the donations.

 

[terryforsythe]

Google does not know ANYTHNG (EXACTLY the SAME as AI). It just collates information. If there is more information saying that something is a problem, then it sways that way, even if the issue was debunked. Particularly after it was debunked. As there is little information from the side that debunked it after it's debunking. But there will still be more information from those that were debunked, trying to say "It ain't so") to those that debunked the BS. And because there is that "after the fact" of the debunking information, it decides to go on that, just because there is more total information in that direction.
Hence, both Google and AI are frequently WRONG but believed by people that don't understand this and hold Google (and/or AI) up on a pedestal of ("because Google [or AI] said it, it must be the case.

That is why I stated:

(take it with a grain of salt)

and

(recall the grain of salt thing)

This is why one must do their own research and also discover "who is being paid by whom" for these papers.

What have you discovered in your research?

 

[EJ3]

That is why I stated:

and



What have you discovered in your research?

I haven't done any research on the subject since the 1980's, when it was debunked and should have stayed that way.
I don't catalog what I do, I just do it, file it in my brain in case something comes up that changes it and do what I do best: take care of me and mine. (I wanted to say what I do best is "Show Off" but that would be too 'Show Off 'E')
If you feel differently about it (which is what you already know about it but are questioning the results), you may accept what you have been told here or not.
If not, the YOU will have to either: Do YOUR own further research (maybe even proving us wrong [or at least @Julf and myself]) but I highly doubt that.
Or hire someone else (not me, I highly doubt that someone would pay me what I would ask per hour [since I have ZERO reason to do anything that takes up my time {unless it is for my wife or my mother}]) to do that for you.
We have told you what we believe to be true, @Julf has provided you with the most modern evidence that I know of on the subject (their may be more, but I don't care to be bothered with it any more).
Since you are a sceptic (usually a good thing) of what we have seen, experienced and believe to be true: THEN it is on you: to prove us wrong: not on us to prove you wrong (or right).

 

[terryforsythe]

Have you been drinking just a little too much tonight?

I quoted Google AI debunking the premise that it is caused entirely by negative feedback - it is slew rate, not just negative feedback alone - noting to take it with a grain of salt (because it is AI). Then you state:

I haven't done any research on the subject since the 1980's, when it was debunked and should have stayed that way.

So, you agree with Google AI that it is not just negative feedback - it is really about the slew rate?

If not, the YOU will have to either: Do YOUR own further research (maybe even proving us wrong (or at least @Julf and myself) but I highly doubt that.

What is there to prove wrong? What is it that you have posted that is contradictory to what I posted?

Indeed, you went in a tirade about AI in post #2,130, but you did not indicate what I quoted from AI in my post that was incorrect. Please clarify.

We have told you what we believe to be true

What, specifically, have you told me to believe to be true that I have disputed?

 

[EJ3]

Have you been drinking just a little too much tonight?

I quoted Google AI debunking the premise that it is caused entirely by negative feedback - it is slew rate, not just negative feedback alone - noting to take it with a grain of salt (because it is AI). Then you state:

So, you agree with Google AI that it is not just negative feedback - it is really about the slew rate?

What is there to prove wrong? What is it that you have posted that is contradictory to what I posted?

Indeed, you went in a tirade about AI in post #2,130, but you did not indicate what I quoted from AI in my post that was incorrect. Please clarify.

What, specifically, have you told me to believe to be true that I have disputed?

Don't drink.
But did drive over 1400 miles in the last 24 hours.
I tried very nicely to explain to you that you needed to find your information somewhere other than me.
So now I find that you are VERY RUDE in your quite DEMANDING response to me.
It is nice that they provide an ignore button on this site.
I will now implement it for a while.

 

[terryforsythe]

I tried very nicely to explain to you that you needed to find your information somewhere other than me.

I found and posted information, but you criticized my post even though, as far as I can tell, the information I posted didn't contradict anything you posted.

That is why I found your posts so bizarre. I don't think we had any disagreement on the subject of TIM, but you crapped all over me because I quoted AI. Sometimes AI is correct, and sometimes it's wrong. I know that, which is why I said, more than once, to take it with a grain of salt.

So now I find that you are VERY RUDE in your quite DEMANDING response to me.

And you don't think the following response by you to my post was RUDE and DEMANDING of me?

I haven't done any research on the subject since the 1980's, when it was debunked and should have stayed that way.
I don't catalog what I do, I just do it, file it in my brain in case something comes up that changes it and do what I do best: take care of me and mine. (I wanted to say what I do best is "Show Off" but that would be too 'Show Off 'E')
If you feel differently about it (which is what you already know about it but are questioning the results), you may accept what you have been told here or not.
If not, the YOU will have to either: Do YOUR own further research (maybe even proving us wrong [or at least @Julf and myself]) but I highly doubt that.
Or hire someone else (not me, I highly doubt that someone would pay me what I would ask per hour [since I have ZERO reason to do anything that takes up my time {unless it is for my wife or my mother}]) to do that for you.
We have told you what we believe to be true, @Julf has provided you with the most modern evidence that I know of on the subject (their may be more, but I don't care to be bothered with it any more).
Since you are a sceptic (usually a good thing) of what we have seen, experienced and believe to be true: THEN it is on you: to prove us wrong: not on us to prove you wrong (or right).

It is nice that they provide an ignore button on this site.
I will now implement it for a while.

On that, I fully agree with you!

 

[Panelhead]

"The Topping B100 features a rated slew rate of ± 350 V/μs. This highly responsive "Diamond Differential" circuitry allows for extremely fast transient recovery and helps to virtually eliminate transient intermodulation distortion (TIM)."

It sure where this tidbit was gleaned from. If correct, that is impressive.
My pair soldier on. Not sure at what voltage and power outputs. The LS II’s are hitting mid 90’s on peaks. At 35’ from speakers. So maybe little over a 100dB at a normal distance.