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Topping B100 Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 23 5.8%
  • 2. Not terrible (postman panther)

    Votes: 22 5.6%
  • 3. Fine (happy panther)

    Votes: 77 19.5%
  • 4. Great (golfing panther)

    Votes: 272 69.0%

  • Total voters
    394
[I was going to add this as an edit to another post, but I think it deserves it's own post.] I'm going to expand a bit on an earlier thought about why we have not seen a lot of amplifiers like this, despite knowledge of how to achieve this performance level being public domain for decades. There is a potentially significant issue for manufacturers, and that is the "commoditization" problem, the death of their entire industry, and ruin of a significant part of this hobby--amplifiers.

DACs were ruined once when the jitter problem was solved in the early 2000s, came back due to streaming, but are essentially ruined again. There is hardly any point in designing or selling one for more than $100 since for $100 you can get something that measures almost perfectly six ways from Sunday in dynamic tests, static tests, you name it. Not everyone realizes it yet, but they will soon enough. As an audiophile item, DACs are living on borrowed time.

Amplifiers have avoided dying as an audiophile product. But what if, 30 years ago, manufacturers started selling straight wires with gain (which they all could have)? With very little fanfare, one of these things actually was designed and stuffed into a PA amplifier in about 1996. Well under .01% THD at any frequency at any power level up to 500W. And I think it cost about $900. That's basically "solved". No one followed. Why not? Partially, fear of the 80s, where amps were "solved" but really weren't since the measurements weren't good enough (i.e. they were not measuring the right thing). But more importantly, if everyone follows, and everything measures below any possible level of audible consequence, the amplifier becomes little more than a blender or a box fan, and they've all gone and put themselves out of business. Benchmark repeated the low distortion performance and added a switching supply to get the noise out, and once again, no one followed. It took decades for Krell or any "boutique" manufacturer to do this (edit: forgot Halcro and Boulder ... which no one followed, again), but they finally are. Linn, Krell, and EMM Labs amps all recently measured by Stereophile show distortion levels from 20Hz to 20kHz that aren't ridiculously bad (read: 1978 levels). 20Hz to 20kHz flat lines below .01%. Very little of any likely audible consequence in any of them. How long can they all sell the same product? What if they all really did sound different before because they were all purposefully imperfect? And now Topping is selling perfection, outside of power levels, for $300. But, the B200 solves some of the power issues for $600. I suspect with a stereo chassis they could solve all of them for about $2000.

What if, say, perhaps not Topping but Parasound, Rotel, or NAD break their adherence to decades old designs and go and sell a 400wpc amp for $2500? Hypex couldn't do it with Class D (so far) since the problems (as they've admitted) are more difficult to solve there, and the elusive "flat line from 20Hz to 20kHz" is more difficult to achieve. But they're getting there. But this thing is just straight lines. No sane person could claim there is anything measured even possibly of consequence. It's a wire with gain. Now, I'll never put it past many audiophile to come up with wild levels of faith and superstition, but at some point, the jig is up. The subjectivists and objectivists have always had at least some deviations in the measurements to fall back on--"well, I can hear that" (you can't, but whatever). But if you throw every measurement in the book at something and it never does anything except perfectly amplify what you stuck in the input jacks, they've gone and screwed themselves. You can't improve or innovate on perfect. I mean, what can Topping do to follow up on this short of adding more power or meters or some other triviality? Nothing. They can sell one to everyone who wants one, and so long as it doesn't break, that's it.

This is not just a potential end game amplifier for some, but if this performance level were adopted industry-wide, it could the end of the whole game. Will the industry ever do it, and cause the death of the hero amp? We'll see.
I don't think DACs have died as an audiophile product and I don't think amplifiers will either. I think there's probably more external DACs being used right now than just about any time in history.

The objectivists are definitely on the upswing compared to the days of Peter Aczel's The Audio Critic often seeming like a lone voice crying out in the wilderness. But subjectivism will never be truly stamped out. People will always want fancy things made in ways that can't be easily commodified. And people will always hear differences outside of extremely difficult to reproduce blinded circumstances.
 
PURIFI 1ET400A 4Ω, 1%THD+N = 425 W

It is a very good amplifier. But, at 425W the THD+N is higher than 1% according to Amir's test results. It hits 1% at less then 400W:

Purifi 1ET400A Class-d Amplifier Module Power into 4 ohm Audio Measurements.png



If you want less than 1% THD+N at 425W, sell your 1ET400A and get the 1ET9040BA. Also, be sure you have 8V to drive it, or use in I/O module to increase the gain.
 
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That external power supply for the monoblocks, which are supposed to be near the speakers, are a absurd design choice.
 
Thanks for the review @amirm, excellent little amp. As others wished, I wish it had an internal PSU at least. Using two of these with two speakers and then a DAC and a Streamer would result in a bit of a cable vomit behind the scenes. I shall wait for an integrated with PSU inside.
 
There seems to be a circuit misunderstanding. Power supply output impedance is not equivalent to amplifier output impedance. An amplifier with high feedback factor may have very low output impedance even if its power supply has output impedance in units of Ohms. The result of higher power supply impedance is decreased maximum output power of the amplifier.

Correct. The output impedance of the amplifier is not the same thing as the impedance the power supply presents to the audio circuits it feeds.

The result of higher power supply impedance is decreased maximum output power of the amplifier....differing with frequency too.

But I don't want to get too obsessed with this point. Since voltage regulators provide a stiff power supply with low impedance to the audio circuits, using well designed supplies solves these issues for the most part.
 
My goodness. Typos, confusion.

I'll say it again. If this is actually a class B output stage, color me impressed!

How does it sound in use? Indistinguishable from a well designed class A or class D amp within their limitations, e.g., at 1 watt output into a good speaker with reasonably sensitivity of maybe 85dB/1W/1m?
I’ve owned a pair for a week now. They sound great and yes, I likely cannot consistently pick them in an ABX against V3 Monos (I’ve owned both as well as a pair of ZA3s). Pushing a pair of KEF LS50 Metas (supplemented by an SVS SB-3000).

-Ed
 
I miss an option in the rating:
[x] confused.

For an analog amplifier design the heat sink and air ventilation is much too small.
I would expect it to overheat within minutes when you drive this amp at 1/3 of rated power.
 
Well, if it really is running in class B, the output devices will be shut off half the time in normal operation, so they won't require the giant heatsinks warm biased class AB output stages need.
 
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Not sure what you don't agree with. Firstly, your comment "The power supply is 100% in the signal path in almost all audio amplifier designs" is completely wrong at all levels.

Now you are saying something different. You are now alluding to different things.

OK, please show. Without an actual example, this is an anecdote.

Again, please show.

Well, let's read some posts about psu design for amplifiers.


In the EETimes article, by using a regulated voltage supply instead of an unregulated voltage supply "Clipping behavior will be cleaner, as the clipped peaks of the output waveform are not modulated by the ripple on the supply rails. Having said that, if your amplifier is clipping regularly you might consider turning it down a bit."

That right there is a change in sound quality.
And a clue: "...the clipped peaks of the output waveform are not modulated by the ripple on the supply rails."
Power supply ripple modulates the audio output waveform.

[I know this is an engineering problem that has been solved, but the point I made was that the power supply is part of the signal path and has influence on the audio output, meaning that if you hobble even the best audio amplifier circuit with a poorly designed, noisy, high impedance power supply, the sound quality from that 'best' audio amplifier will definitely suffer, first objectively (measurements) and if bad enough, subjectively too.]

I once had a simple push-pull 300B tube amp rigged up, with an external power supply. I made a giant regulated supply using a 6336 pass tube and a 12AX7 differential stage as the error amplifier, along with an 0D3 as a voltage reference. It changed the sound of the amplifier in subtle ways, but bass was tighter with the midrange sounding less 'tubey' and more like a very good solid state amplifier. I could jumper out a few things and switch it back to an unregulated 'passive' power supply, which absolutely increased the power supply impedance. The resulting sound was more in line with what you'd expect from a vintage tube amplifier, with that more ill-defined, slightly woolly bass and what I thought was a more tubey sounding midrange (although I admit that was probably my own biased opinion, not based on real differences I'd stand by now).

At one point I tried to lower the B+ voltage by adding a high power/low value resistor in series from the power transformer center tap to ground, which did lower the B+ voltage but also really raised the power supply impedance. I could really hear that! The bass got all bloated and loose.

All that's just anecdotal, I know. But it was an experiment I ran for myself to prove/disprove effects of power supply impedance on a simple push-pull triode output stage.

Anyway, the articles I linked to answer the question. Please read them and quote whatever you like to disprove any points I've made or prove any points you've made. The whole point is to try to be 'scientific' here on Audio Science Review. Right?
 
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The problem is that NFB destroys the sound, hence why the THX AAA Benchmark AHB2 and the likes sound dead and closed in, a cold sterile tool with no enjoyment.
 
The problem is that NFB destroys the sound, hence why the THX AAA Benchmark AHB2 and the likes sound dead and closed in, a cold sterile tool with no enjoyment.
At the risk of once again being derided for subjective input, I will tell you my pair of B100s do not sound sterile or closed in at all—I got that sensation when I auditioned an SMSL SA400, which I purchased used and immediately sold right back off because of that dead, lifeless sound despite its wonderful measurements. The Fosi Class-D amps and the B100s sound wonderful in comparison, so I politely disagree with your blanket statement in spite of the B100’s triple nested feedback design.

-Ed
 
The problem is that NFB destroys the sound, hence why the THX AAA Benchmark AHB2 and the likes sound dead and closed in, a cold sterile tool with no enjoyment.
I have a pair of Topping LA90D amplifiers and a Hypex Nilai Stereo amplifier, and they all sound fantastic. I assume they are using negative feedback, but that may or may not be the case.
 
I have a pair of Topping LA90D amplifiers and a Hypex Nilai Stereo amplifier, and they all sound fantastic. I assume they are using negative feedback, but that may or may not be the case.
I doubt there's an amp on the market that doesn't use negative feedback in some capacity (though manufacturers will often play word games like "no overall loop feedback!" to satisfy audiophile ignoramuses like the one you quoted - what qualifies as acceptable use of feedback and not, and more importantly why, is not really articulated). It's kind of hard to avoid if you want to design something approaching high fidelity.

Moreover, pretty much every recording has gone through all sorts of NFB-employing circuits and converters on its way to your ears, but as usual in the land of audiophile old wives’ tales, the last bit magically "destroys the sound".
 
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The problem is that NFB destroys the sound, hence why the THX AAA Benchmark AHB2 and the likes sound dead and closed in, a cold sterile tool with no enjoyment.
Uh huh.
 
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