Topping B100 Monoblock Amp

Cos

Cos

Audioholic Samurai
I was reading the review of this tiny AMP and it seems to measure well. 100 watts @ ohms is no slouch, but it is Class B. 83w at 8ohms.
  • Every amp I have owned up until the ATI Class D has been class AB. (Anthem, Parasound)
  • This amp is only class B, is there any disadvantage to this? At $299.00 the Topping B100 seems like an insane deal?
 
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Verdinut

Verdinut

Audioholic Spartan
A Class B amp is typically known to generate output crossover distortion. That is the main reason why the Class AB topology was designed.

Edit: But contrarily to what Amir says, IMO this Topping B100 monoblock power amp does not operate as a true Class B amplifier. It was tested by him and it had an outstanding performance:
It would be good to have @PENG to chime in with his opinion.
 
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TLS Guy

TLS Guy

Seriously, I have no life.
I was reading the review of this tiny AMP and it seems to measure well. 100 watts @ ohms is no slouch, but it is Class B. 83w at 8ohms.
  • Every amp I have owned up until the ATI Class D has been class AB. (Anthem, Parasound)
  • This amp is only class B, is there any disadvantage to this? At $299.00 the Topping B100 seems like an insane deal?
At one watt it won't be pretty unless it uses Peter Walker's current dumping topology, which uses a small class A amp in a feed forward mode to correct the dumpers. I doubt it does as they would be too stupid to figure it out. That amp is junk. Avoid.
 
lovinthehd

lovinthehd

Audioholic Jedi
For $300 and only 50w into 8 ohm, what is the attraction to this amp?
 
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ski2xblack

ski2xblack

Audioholic Samurai
Amir's measured performance of the amp is rather Impressive. Incredible, even. How much negative feedback does it take for class b to actually do that? I wouldn't have thought it possible, but I'm educated in the lowly biological sciences. Where's @PENG ?

What jumps out at me as obvious flaws would be a)the modest power and b)hair trigger protection circuitry. That seems to severely limit it's utility. On the value front, there are lots of more proven class d alternatives for similar cost to choose from that don't have the power limits and load compatibility compromises.

I would wait and see how reliable they are before calling it junk, though. If it's reliable and offers such SOTA distortion performance, that's pretty cool. That being said, I would let the SINAD obsessives be the guinea pigs with it.
 
ban25

ban25

Audioholic
This is a pretty unimpressive product for the price when you consider that it's only putting out 50W @ 8Ohms, and it's a monoblock, so you need two of them, alongside their giant outboard wall wart transformers.

And that's before you get into Topping's questionable reliability. Likely over half of all Topping PA5 amplifiers ever made have failed:


Possibly more given that some users are on their 3rd unit. The shoddy cooling and encapsulation was not solved by Topping on the PA5 II. It was left to the community to devise a fix:


Keep in mind the PA5 still has Amir's top rating (golfing panther). There is no testing for reliability or longevity in ASR reviews.
 
P

PENG

Audioholic Slumlord
This is a pretty unimpressive product for the price when you consider that it's only putting out 50W @ 8Ohms, and it's a monoblock, so you need two of them, alongside their giant outboard wall wart transformers.

And that's before you get into Topping's questionable reliability. Likely over half of all Topping PA5 amplifiers ever made have failed:


Possibly more given that some users are on their 3rd unit. The shoddy cooling and encapsulation was not solved by Topping on the PA5 II. It was left to the community to devise a fix:


Keep in mind the PA5 still has Amir's top rating (golfing panther). There is no testing for reliability or longevity in ASR reviews.
As often, I agree with you, but to be clear and fair, they may be the answer to people who use their amps under one of more of the following use conditions:

- Speakers with relatively high sensitivity.
- 4 ohm nominal speakers.
- Near field use, such as desktop, studio, small family, bed rooms.
- user desire the most transparent amp, regardless of distortions level that are widely accepted as below the threshold of audibility.

Under the above conditions, they they could have an amp that meets their power requirements, but cost a lot less, yet exceed the audio specs of one of the best measured Benchmark AHB2 (on ASR).

Bottom line, if someone needs no more than 100 W peak for his/her 4 ohm rated speakers, for <$1000, he/she could have the best measured little amplifier. As to reliability, we have to wait and see, but being that it is "class B" and appears to have quite a few ICs on board, it probably will be quite reliable, assuming Topping has put those ICs to good use in terms of implementing protective schemes that will offer more than adequate protection against overload, heat, short circuits, transients etc.

I went to the Audiofest in Toronto yesterday, in most demos, those huge and expensive, all >20,000 a pair speakers were drawing relatively low "power", say from 0.1 W to 20 W most of the time, at spl that I could barely withstand for longer than a few minutes, and in rooms from small to medium large. There were a couple of speakers that were able to demand between 4 to 45 W, but none topped 50 W peak for sure, the only demo room we missed was the Marantz/B&W.

You can't have too much power, and one doesn't realize how little power they actually need, are both true.

But, no, obviously the little and weak (relatively speaking) B100 is not for everyone, but could be good for many, at least making their owners feel they have the most transparent amplifier that truly amplify the input signal without adding measurable (iiuc, distortions.

Quoting Amir:

"The analyzer noise actually takes over around 30 watts as it changes its gain to accommodate higher voltage (the step up). "

"The protection circuit is aggressive with 4 ohm load, not allowing the amplifier to go into clipping"

By the way, this class B amp has around 100 dB SINAD, ie 0.001% THD+N down to just 20 miliwatt, that pretty much means nothing beats it in crossover distortions including class A amplifiers!!!

So, just about the only limitations is the low output capability that makes it mainly/only attractive to users I mentioned above.

There is always the B200, and I bet Topping will eventually make one that can be bridged, to up the limit to potentially 200 W 8 ohms, 320 W 4 ohms, then I think even you may consider one lol..


1729516286875.png
 
ban25

ban25

Audioholic
As often, I agree with you, but to be clear and fair, they may be the answer to people who use their amps under one of more of the following use conditions:

- Speakers with relatively high sensitivity.
- 4 ohm nominal speakers.
- Near field use, such as desktop, studio, small family, bed rooms.
- user desire the most transparent amp, regardless of distortions level that are widely accepted as below the threshold of audibility.

Under the above conditions, they they could have an amp that meets their power requirements, but cost a lot less, yet exceed the audio specs of one of the best measured Benchmark AHB2 (on ASR).

Bottom line, if someone needs no more than 100 W peak for his/her 4 ohm rated speakers, for <$1000, he/she could have the best measured little amplifier. As to reliability, we have to wait and see, but being that it is "class B" and appears to have quite a few ICs on board, it probably will be quite reliable, assuming Topping has put those ICs to good use in terms of implementing protective schemes that will offer more than adequate protection against overload, heat, short circuits, transients etc.

I went to the Audiofest in Toronto yesterday, in most demos, those huge and expensive, all >20,000 a pair speakers were drawing relatively low "power", say from 0.1 W to 20 W most of the time, at spl that I could barely withstand for longer than a few minutes, and in rooms from small to medium large. There were a couple of speakers that were able to demand between 4 to 45 W, but none topped 50 W peak for sure, the only demo room we missed was the Marantz/B&W.

You can't have too much power, and one doesn't realize how little power they actually need, are both true.

But, no, obviously the little and weak (relatively speaking) B100 is not for everyone, but could be good for many, at least making their owners feel they have the most transparent amplifier that truly amplify the input signal without adding measurable (iiuc, distortions.

Quoting Amir:

"The analyzer noise actually takes over around 30 watts as it changes its gain to accommodate higher voltage (the step up). "

"The protection circuit is aggressive with 4 ohm load, not allowing the amplifier to go into clipping"

By the way, this class B amp has around 100 dB SINAD, ie 0.001% THD+N down to just 20 miliwatt, that pretty much means nothing beats it in crossover distortions including class A amplifiers!!!

So, just about the only limitations is the low output capability that makes it mainly/only attractive to users I mentioned above.

There is always the B200, and I bet Topping will eventually make one that can be bridged, to up the limit to potentially 200 W 8 ohms, 320 W 4 ohms, then I think even you may consider one lol..


View attachment 70177
The biggest issue in my mind is reliability. Even an aggressive protection circuit will not stop a failure over time due to thermal cycling. Right behind that is the question of value. Yes, it measures well, in only one dimension: SINAD. You can argue the "feel-good" value of a transparent amp, but when the harmonics are already well below the ambient noise floor, does it matter? On the other hand, power really does matter when you are talking about levels this low.

Similar to your experience, when I check the meters on my MC302, I often find them hovering around 300 mW per channel driving my Blade 2 Metas. This is normal listening, maybe -30 dB on the relative scale. However, in a home theater context, I can easily peg the amp at 300W+ out of the 4Ohm taps when listening near reference levels (-6dB or so on the relative scale). This can be sustained in scenes with large explosions and so forth. Fortunately, the McIntosh handles this situation very well by capping the output and simply refusing to play louder. ;) That said, should I have gotten the 462 instead? Maybe.

Which goes back to my point that the B100 just doesn't deliver enough power. I'm sure it's fine for near field use, but do you really want all those boxes on your desk? FWIW, I have a Fosi ZA3 in mono mode driving my center channel speaker. It's fine. It delivers considerably more power than these monoblocks at half the price, or less -- and it's probably a lot more reliable.
 
Trell

Trell

Audioholic Spartan
The biggest issue in my mind is reliability. Even an aggressive protection circuit will not stop a failure over time due to thermal cycling. Right behind that is the question of value. Yes, it measures well, in only one dimension: SINAD.
Topping don’t have the best reputation for reliability, that’s true. I wouldn’t buy one of their amps. On the other handhand, at least one high end D-amp manufacturer had/have issues with appropriate cooling leading to premature failure.
 
ski2xblack

ski2xblack

Audioholic Samurai
Yeah, PENG, I read Amir's test, but I'm still left with questions.

I know it's a shot in the dark since little technical info is available, but could you, @PENG , comment on how class b can do what this amp does?

To my understanding, and please correct me where I'm wrong, class A/B operates in 'push-pull' fashion with the output devices conducting >180 degrees, while in class B the output devices conduct <180 degrees. Feedback is pretty amazing, but it can't conjure out of thin air what is missing from between those positive and negative deflections, that in class B constitute <360 degrees of the waveform. Do the output devices conduct 179.999 degrees on each side, thus making it legit class B, and just omit the .001 degree that remains? How does nfb work in that situation? It has to have some signal to work with in order to feed anything back, does it not? What do you think is happening down there?

I suppose that as long as all this is going on at such low levels that it avoids any audible "off/on" jumps in output it should work. I mean we're way down in the residual noise of the constituent devices here, vanishingly low.

I'm intrigued, I guess.
 
P

PENG

Audioholic Slumlord
Yeah, PENG, I read Amir's test, but I'm still left with questions.

I know it's a shot in the dark since little technical info is available, but could you, @PENG , comment on how class b can do what this amp does?
All we know is that they use 3 stages of feedback, presumably negative feedback.

To my understanding, and please correct me where I'm wrong, class A/B operates in 'push-pull' fashion with the output devices conducting >180 degrees, while in class B the output devices conduct <180 degrees.
You are obviously right about class AB, but for class B, I am not sure if there is really a definitive definition lol.. It seems that some may want to define class B as one that use no bias, while others would say something different, such as Doug Self, quoted from his book "Audio Power Amplifier Design" (Page 82)

1729599661977.png


Feedback is pretty amazing, but it can't conjure out of thin air what is missing from between those positive and negative deflections, that in class B constitute <360 degrees of the waveform. Do the output devices conduct 179.999 degrees on each side, thus making it legit class B, and just omit the .001 degree that remains? How does nfb work in that situation? It has to have some signal to work with in order to feed anything back, does it not? What do you think is happening down there?
I am not totally sure, but quoted above probably answer at least part of your questions.

Also, keep in mind that feedback can indeed reduce distortions of all kinds, linear and non linear types. Use alone, obviously it cannot eliminate crossover distortions but it can reduce it, while create other sort of distortions that could be mitigated by other means.

As to the B100, Topping is not going to tell us the details even if we ask them, so what they published such as the 3 stage of feedback used, is all we are going to know, I assume...

I suppose that as long as all this is going on at such low levels that it avoids any audible "off/on" jumps in output it should work. I mean we're way down in the residual noise of the constituent devices here, vanishingly low.

I'm intrigued, I guess.
Me too, but it's no different than when Quad first introduced the "current dumping" concept, that also (as @TLS Guy alluded to earlier) allowed the use of the class B (or C?) amp for the so called "current dumping". At the time, I bet people found the current dumping concept amazing, and intrigued too, though apparently in recent times, they might have reverted back to more traditional ways, such as class A, AB varieties.

I doubt Topping use the current dumping scheme but they likely use something more advanced that managed to reduce distortions, including crossover distortions obviously to almost not measurable level.

Sorry, I wish I know the answer...
 
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E

EddNog

Audiophyte
Just joined Audioholics to follow this thread so I can see what you guys come up with. I have owned a pair of B100s for the past few weeks and I love them. They sound amazing in my setup (replaced a pair of Fosi V3 Monos), and while I have tripped the safety a couple of times pushing volume to very uncomfortable listening levels just for the purpose of testing, in my day-to-day listening, I've never tripped safeties or ran into any other issues. I sit about 10' away from the speakers in a ~20'x~30'x10' room. Speakers are KEF LS50 Metas with an SVS SB-3000 subwoofer providing the foundation. Average listening (A-weighted) level is about 60dB from my listening position with peaks up to 85dB.

I had to go over 90dB A-weighted peak for the safety to kick in during my stress testing.

In terms of sound, they are flawlessly transparent and noiseless. There is zero audible sound from my speakers when sitting idle with my ear under an inch from the concentric driver, not even a hum or hiss. The amplifiers themselves run luke warm even after hours of listening. From a convenience standpoint, my setup couldn't possibly be less work to use, as I use a HiBy R6 Pro II DAP as my streamer/source (which I control remotely using the HiByCast app from my phone or tablet), feeding a Topping E70 Velvet DAC set up in preamp mode, which directly feeds the B100 monoblocs via XLR and the subwoofer via RCA. I have the 12V trigger output connected to the monoblocs and the subwoofer as well, so I can listen to music any time without having to walk up to the system to turn it on and I need not do that to shut it down, either. Even with the most dynamic/lowest volume recordings in my collection (Carmen Fantasy After Bizet by All-Star Percussion Ensemble), the system will play loud enough for me before I max out volume.

-Ed
 

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