Topping B100 Amplifier Review

[terryforsythe]

Probably not. There's a calculation for that, but it typically degrades the worst component a dB or two (strictly speaking, that's just adding noise, but that's all there probably is to add). In your example, since it is 10dB better than the amp, you'll end up with maybe 84dB.

I just ran the calculation, assuming -95dB of THD+N for the DAC and -85dB THD+N for the amplifier, and an amplifier gain of 20dB. The DACs noise/distortion will be amplified by the amplifier, along with the signal. Adding the gain 20dB to the DAC's THD+N value we get -75dB, which is the THD+N output by the amplifier due to the DAC's noise/distortion contribution. Combining that with the Amplifiers own noise/distortion we get -72.61dB.

 

[restorer-john]

I just ran the calculation, assuming -95dB of THD+N for the DAC and -85dB THD+N for the amplifier, and an amplifier gain of 20dB. The DACs noise/distortion will be amplified by the amplifier, along with the signal. Adding the gain 20dB to the DAC's THD+N value we get -75dB, which is the THD+N output by the amplifier due to the DAC's noise/distortion contribution. Combining that with the Amplifiers own noise/distortion we get -72.61dB.

You can't make any assumptions. THD+N for a DAC varies with level as does THD+N for an amplifier. Numbers are only valid at one level and when the system is measured as a whole.

 

[terryforsythe]

You can't make any assumptions. THD+N for a DAC varies with level as does THD+N for an amplifier. Numbers are only valid at one level and when the system is measured as a whole.

It was just a simple example for discussion of the effect, not a review of any particular DAC or amp.

 

[eddantes]

Your understanding of your power requirements are potentially horrifically wrong. Go watch the Harbeth video about how much power you need. They ran a pair of similarly inefficient Harbeth speakers with a CH Precision amp that had fairly accurate watt meters. It was not particularly loud, and the speakers were not in distress. Guys were literally going up to the speakers and putting their ears near them and you could still hear them talking in the room. They were peaking well over 600 watts. Poor Alan Shaw was standing there with a look of disbelief on his face. Granted, that a track that drew a lot of power. On some boring chamber music they barely hit 50.

I think I showed my work. Where is my math wrong?

Certainly more is more. And yes - there are music recordings with dynamic range that may possibly reach 35db of DR, maybe more, who knows? These are edge cases however.

So where is my math wrong? Not starting anything or being confrontational, please don't misread me. I am here to learn.

 

[EddNog]

Left to right B100, L70 (as preamp), E70 Velvet, B100

Say what you want about the power ratings. Doesn’t even matter because this sounds absolutely phenomenal driving a pair of LS50 Metas and an SVS SB-3000.

Happily calling this my endgame setup!

-Ed

 

[Old_School_Brad]

Left to right B100, L70 (as preamp), E70 Velvet, B100

View attachment 393709

Say what you want about the power ratings. Doesn’t even matter because this sounds absolutely phenomenal driving a pair of LS50 Metas and an SVS SB-3000.

Happily calling this my endgame setup!

-Ed

PS No, I don’t have the doorstops there for acoustic reasons. They keep my amps in place so the heavy cables don’t move or shift the amps if my cats get too touchy-feely.

Horses for courses.

P.S. Not our cats, not my kids, not even my wife (unless she is angry perhaps), can lift my amplifier. I placed it there. It stays there.

 

[EddNog]

Horses for courses.

P.S. Not our cats, not my kids, not even my wife (unless she is angry perhaps), can lift my amplifier. I placed it there. It stays there.

Old school sounds accurate! ;-)

 

[Old_School_Brad]

Old school sounds accurate! ;-)

You assume I'm living in the past by this comment because of my user name. Fair enough I guess.

My amplifier is a SMPS powered class (A)B amplifier.
I stream all my music via. a Wiim Pro Plus.
I use Dirac Live.

Because you got the subwoofer, taking the load off of your system. And you listen at quite low volume per your post #535.
Means you don't need more than a handful of watts perhaps.
Yet your posts seem a bit prudish and disassociated towards the talk about power needs in other, vastly different situations from yours.
Hence my "horses for courses" comment.

I think your setup is the optimal and intended use case for these small new amps and can see why you consider it end game, even if I think this is a lie you tell yourself..

 

[SCR]

Left to right B100, L70 (as preamp), E70 Velvet, B100



PS No, I don’t have the doorstops there for acoustic reasons. They keep my amps in place so the heavy cables don’t move or shift the amps if my cats get too touchy-feely.

It took me a moment to unsee the four digital cameras on the top and actually see the components.

 

[MAB]

I can basically press my ear up against the coaxial driver on my LS50 Metas when hooked up to the B100 and I hear nothing. Not the case with the Fosi amps.

-Ed

I think this is the biggest audible benefit, for those who have quiet space and especially sensitive speakers. Here is a comparison of noise using a JBL D2 compression driver + M2 lens, a microphone stuck in the mouth of the lens, hooked up to a few different amps, including an old Aiwa micro integrated amp.
The Aiwa is noisy and easy to hear within a meter of the speaker. The Bryston, Marantz, Hypex, and PuriFi all have successively better performance, and need to get my ear within few cm of the lens to hear the noise. The black trace is the speaker grounded (essentially measuring the background of my room through the impedance of the M2 lens).

I would expect this B100 to perform really well in this application where power isn't as big a deal as noise.

 

[geekosa]

Hello, is it better to take 2 B100 or 1 LA90D ?

 

[Mort]

Hello, is it better to take 2 B100 or 1 LA90D ?

Search 'L90D' in this thread for several posts about this. They are nearly identical.

 

[Sokel]

Left to right B100, L70 (as preamp), E70 Velvet, B100

View attachment 393709

Say what you want about the power ratings. Doesn’t even matter because this sounds absolutely phenomenal driving a pair of LS50 Metas and an SVS SB-3000.

Happily calling this my endgame setup!

-Ed

PS No, I don’t have the doorstops there for acoustic reasons. They keep my amps in place so the heavy cables don’t move or shift the amps if my cats get too touchy-feely.

We both know that it would take a while calling it endgame.
It's not that you need more.

But (staying with Kef) you will always wonder what an amp that is not current limited can do.
(Kefs are famous for been power hungry,what people misjudge is it's the current element of the equation that they need staying under 4 Ohm for most of their spectrum)

 

[shuppatsu]

Your understanding of your power requirements are potentially horrifically wrong. Go watch the Harbeth video about how much power you need. They ran a pair of similarly inefficient Harbeth speakers with a CH Precision amp that had fairly accurate watt meters. It was not particularly loud, and the speakers were not in distress.

I watched that video, then tracked down the track they were playing. Not quite my cup of tea, but it has some nice things going for it. The track has a ton of subbass starting at around 30Hz. This might be what's drawing all that power. Strangely with my headphone setup I actually had to turn the volume down compared to something with a much lower DR because the pulsing subbass was so irritating. I put my HPA into high gain and tried to see how high I could get it without pain, and the result was...not very high. So I'm not sure how the Harbeth people were pumping 600 watts and putting their heads near the speaker.

 

[Haskil]

Left to right B100, L70 (as preamp), E70 Velvet, B100

View attachment 393709

Say what you want about the power ratings. Doesn’t even matter because this sounds absolutely phenomenal driving a pair of LS50 Metas and an SVS SB-3000.

Happily calling this my endgame setup!

-Ed

PS No, I don’t have the doorstops there for acoustic reasons. They keep my amps in place so the heavy cables don’t move or shift the amps if my cats get too touchy-feely.

You will be at the end of the road when you dare to use standard cables whose weight will not pull the amps backwards. You will then put the door blocks back where they are needed...

 

[Bach]

Excellent measuring amp with good figures on both low and high frequencies.
Usable for most two way speakers ( 5 to 7 inch woofer with a tweeter), to say 95 dB at one meter, which is my recommended max. thermally and distortion wise.

 

[gavagai]

Your understanding of your power requirements are potentially horrifically wrong. Go watch the Harbeth video about how much power you need. They ran a pair of similarly inefficient Harbeth speakers with a CH Precision amp that had fairly accurate watt meters. It was not particularly loud, and the speakers were not in distress. They were peaking well over 600 watts.

A huge part of the peaking of 600w can be thermal and not acoustical watts if the speakers have a very high EPDR and the track used pushes a lot of energy precisely to the point of this EPDR. Hence the relatively low loudness and the high wattage. (Topping is not responsible for a high EPDR)

By the way your understanding of sensitivity (and the generally accepted understanding of the idea of sensitivity of a speaker) is totally wrong.

The only sensitivity which is independent of the context is the sensitivity of a speaker from 20Hz to 20Khz. In this case, the sensitivity of speakers that have almost the same driver area are roughly the same.

The sensitivity present in this thread is dependent of the context, i.e. of an implicit band limiting of the frequency response. There's two usage of this :

1. Matching drivers in speakers building. Hence a tweeter can has 92dB of sensitivity in a band limited situation (the part of the frequency response which is flat). In the 20Hz - 20Khz range a tweeter doesn't have a 92dB sensitivity at all.
2. To estimate the subjective loudness of a speaker without taking in account the bass response.

Two speakers can have the same independent sensitivity, but two very different band limited sensitivity.

You can't use band limited sensitivity to determine if the wattage of an amplifier is adequate because it's somewhat a subjective argument versus an objective measurement.

 

[terryforsythe]

Hello, is it better to take 2 B100 or 1 LA90D ?

B100 Advantages:
2 x B100 is less expensive than 1 x LA90D.
2 x B100 put out slightly more power than 1 x LA90D in two channel operation.

LA90D Advantages:
Volume control if you need it, and it can be bypassed if you don't need it.
Can be bridged mono, allowing you to add another down the road and put out a lot more power.

Check out Amir's review of the LA90D for further details.

 

[terryforsythe]

Yet your posts seem a bit prudish and disassociated towards the talk about power needs in other

That statement is uncalled for.

There has been much discussion in this thread about the B100 being too low on power. For some that may be true, for others it may not be true, depending on their room, speakers, and the manner in which they intend to use their amplifier, e.g., the volume at which they listen to their music. EddNog has presented his perspective (I also have presented mine) to add balance to the discussion. Moreover, EddNog is presenting his perspective based on his actual experience using the amplifier, not just speculation.

 

[ryanmh1]

You can't use band limited sensitivity to determine if the wattage of an amplifier is adequate because it's somewhat a subjective argument versus an objective measurement.

Not like you can have impedance/phase plots on hand for everyone's speakers. That why I said potentially. I'm assuming running without an active crossover and subwoofer, and desiring at least 20db headroom over average on any program material. Ideally, you want, oh, at least 105db peaks. But I'll grant there are people who never go above background levels. 50W on 85db speakers might do it then.