Topping B100 Amplifier Review

[Maciekw]

Basically, regardless manufacturer’s claims and specs, and based on laws of physics, electrical circuit engineering of class B/AB linear amplifiers and laws of thermal conduction, it is a 5W/4R continuous power amplifier.

Stop repeating your opinions, which you have already presented dozens of times. Please

 

[LKA]

When I simulate a single-supply (+38V) class-b BTL amplifier at 5W/4R I get 32W dissipation.

 

[Sokel]

I don't understand the debate here.
We have two sets of data from experienced operators (Amir and pma) who speak for themselves.

Can we move on please?It's on Topping's side now to prove otherwise and our opinions are of little use.

 

[pma]

Class B (AB just not closed), PSU 38Vdc (2x19V), 4ohm load, power analysis at 9W/4ohm

(click to see full image)

One transistor power loss in the BTL mode is almost 18W. At 9W usable power.

We have two sets of data from experienced operators (Amir and pma) who speak for themselves.

With almost same results.
------------

Note: @miero might try 5W/8ohm (6.3Vrms) sine for 5 minutes. It would eat only about 8W per transistor. Or 10W/8ohm (8.94Vrms).

 

[pma]

Stop repeating your opinions, which you have already presented dozens of times. Please

I am posting facts, not opinions. That is a big difference from vast majority of posters here, who post based on emotions mostly.

 

[KSTR]

Class B (AB just not closed), PSU 38Vdc (2x19V), 4ohm load, power analysis at 9W/4ohm

Helpful diagram for this, from a famous application note from Burr-Brown (AB-039, POWER AMPLIFIER STRESS AND POWER HANDLING LIMITATIONS, 1993):

For 100W output power this amounts to 40W dissipation in the amplifier worst-case (when output power is also 40W), and that is for purely resistive loads. Conservative design is more like assuming 60% of output power to be dissipated in the amp, with the corresponding implications for thermal design.
It would call for a heat-sink with about 1...2°C/W (effective in-situ!) which of course would be huge....

 

[pma]

Yeah, and BTL is a specific case, when transistors are in fact loaded with a half of load impedance, 2 ohm in case of 4 ohm resistor. Pretty tough, though not such voltage stress.

 

[miero]

@miero might try 5W/8ohm (6.3Vrms) sine for 5 minutes. It would eat only about 8W per transistor. Or 10W/8ohm (8.94Vrms).

It is able to play 50Hz tone having 5W into 8 ohms for 7 minutes without shutdown. Then I stopped the test.

Temperature of the amplifier bottom (hottest part) raised to 42 dg. C.

 

[Maciekw]

I am posting facts, not opinions. That is a big difference from vast majority of posters here, who post based on emotions mostly.

The facts are clear. But if we have several measurements under different conditions giving different results, then by preferring only specific measurement conditions in your statement you are only making an opinion.
According to Amirm, the amplifier has dozens of watts of power, and according to you it is only 5 watts.
Well, and it's cool that you measured in your own way. you wrote about it and anyone who wants can read it. I respect that.
Meanwhile, you've repeated it a dozen times in this thread and thus muddy it up.

 

[mike70]

The facts are clear. But if we have several measurements under different conditions giving different results, then by preferring only specific measurement conditions in your statement you are only making an opinion.
According to Amirm, the amplifier has dozens of watts of power, and according to you it is only 5 watts.
Well, and it's cool that you measured in your own way. you wrote about it and anyone who wants can read it. I respect that.
Meanwhile, you've repeated it a dozen times in this thread and thus muddy it up.

If I understand it right ... Is not in the way you describe and enables that pma needs to repeat again

Amir measurements is about power capabilities and pma measurements are about continuous power. Sounds similar ... but it isn't.

Maybe pma can answer more clearly, I'm not an electronic expert and maybe I'm wrong

 

[pma]

It is able to play 50Hz tone having 5W into 8 ohms for 7 minutes without shutdown. Then I stopped the test.

Great. 5W/8R .....
Would you mind to go higher?

 

[pma]

Amir measurements is about power capabilities and pma measurements are about continuous power. Sounds similar ... but it isn't.

With a stepped sine we have almost same results with amir. Everyone who has a basic knowledge of measurements can see it. If not, then it is not my problem. I am not going to re-measure the amp. There is no reason.

Amir: 50W/8R, 86W/4R
Me: 54W/8R, 94W/4R.
The difference would be in burst lengths.

The whole discussion is about the rated power. Rated power would be 5 minutes sine into 4ohm and 8ohm. This is something we still do not know. We know positively that it will be far below the stepped sine results. @miero can do the job himself - he has a DMM and the 8 ohm load and that is all he needs. Depends if he wants to do it. He is an amp owner and has to decide.

But, frankly speaking, we know that the rated power of all those small Chinese amp boxes is a scam. Not only of this Topping B100. They notify no standards, just some hausnummer numbers.

 

[Jimbob54]

hausnummer

Guessing there is a less literal translation than "House Number" Pavel? Im guessing it alludes to made up? Or meaningless?

 

[miero]

Great. 5W/8R .....
Would you mind to go higher?

Targeting the 10W/8R, the B100 was also able to play 50Hz for at least 7 minutes without shutting down, then I stopped the test.

The temperature of the bottom of the amplifier (hottest part) rose to 45 dg. C, which was only 3 dg C hotter than during the 5W test.

It also seems to me that the small heat sink inside the case is not where the most of the heat is transferred. There are more screws on the bottom of the amplifier case than I would expect just to hold the PCB in place.

Perhaps adding a larger heat sink to the the bottom of the case and standing the amplifier vertically might help in the long run.

 

[staticV3]

Guessing there is a less literal translation than "House Number" Pavel? Im guessing it alludes to made up? Or meaningless?

A ballpark figure would be a rough translation.

Putting a number out there without paying much attention to technical details.

 

[Sokel]

Targeting the 10W/8R, the B100 was also able to play 50Hz for at least 7 minutes without shutting down, then I stopped the test.

The temperature of the bottom of the amplifier (hottest part) rose to 45 dg. C, which was only 3 dg C hotter than during the 5W test.

It also seems to me that the small heat sink inside the case is not where the most of the heat is transferred. There are more screws on the bottom of the amplifier case than I would expect just to hold the PCB in place.

Perhaps adding a larger heat sink to the the bottom of the case and standing the amplifier vertically might help in the long run.

View attachment 410871

I would guess that the main bulk is at the small heatshink though by the fact that the bimetallic switch is installed on it.
Except there's a second one somewhere underneath (which would be a good thing,they are notoriously inaccurate about their ratings)

 

[miero]

Regarding the continuous power testing of B100, we have so far these results to date:

Load 4Ω:

• (deadly) 11.6 Vrms / 33.6W ... dead after 2 seconds ... https://www.audiosciencereview.com/...ping-b100-amplifier-review.57036/post-2151484

Load 8Ω:

• (OK) 8.9 Vrms / 10W ... 7 minutes of 50Hz signal

Who wants to add more data points?

 

[pma]

Let’s say that we estimate, from Amir’s and my stepped level measurements, the rated power to 8 ohm as 50W/8Ohm/1kHz. Then:

1) make 1 hour pre-conditioning at 6.25W/8ohm
2) make 5 minutes sine test at 50W/8ohm

Or, derate the rated power.

 

[DonH56]

The facts are clear. But if we have several measurements under different conditions giving different results, then by preferring only specific measurement conditions in your statement you are only making an opinion.

Not opinion, measured data, confirming the amplifier's inability to meet the current FTC power test. It is failing a defined test standard.

According to Amirm, the amplifier has dozens of watts of power, and according to you it is only 5 watts.
Well, and it's cool that you measured in your own way. you wrote about it and anyone who wants can read it. I respect that.
Meanwhile, you've repeated it a dozen times in this thread and thus muddy it up.

Amir's test is a short-term sweep, not a continuous power test, per the FTC (Federal Trade Commission). A short-term test usually does not stress thermal or other limits whilst the FTC continuous power rating is meant to do exactly that. Many of us lived through the days of wild power claims before the FTC (and various other countries' governing bodies) stepped in to provide some reality and sanity to the marketing claims.

Pavel @pma did not perform some random test he made up; it is a test defined by the FTC. His position has been clear and reasonable during this whole thread despite the protests of those who wish to make up their own definitions and ignore the FTC standard.

ASR is all about holding manufacturers accountable for meeting specified performance standards.

 

[LKA]

Load 8Ω: (OK) 8.9 Vrms / 10W ... 7 minutes of 50Hz signal

Impossible with normal btl class-(a)b and that small heat sink. Total heat generated is 30W.