Topping B100 Amplifier Review

[capslock]

Well, the 15 dB headroom is for peaks, and those numbers are not incompatible with 25 W continious power limit.

I measured with a calibrated pro sound level meter what level I have in my living room that I consider loud. To my surprise, it turned out to be 76 dB/1 m. I always use subs and and active 4th order crossover, so I am probably fine.

 

[capslock]

Are there any answers?

I have used the PA5 (which is more like the PA5 II Plus) for testing of subwoofer drivers (distortion measurements at 30 Hz and the like). It never went into protection, it was more that I started running out of voltage gain.

I have also used the PA5 as a reference when testing vintage amplfies. I don't remember how high I went with output power of continous sine signals but it never went into protection.

 

[antcollinet]

Well, the 15 dB headroom is for peaks,

A combination of short term peaks, plus "crescendos" (so the transient peaks of the crescendo) - but those peaks will reach 100W, so if you want the amp to not clip it needs to be rated for 100W

A 25W rated amp tested with a sine wave cannot do 100W peaks, unless it also has additional short term headroom over and above the conitnuous rating. But if - as is usual - the continuous rating is at the clipping point - it won't have.

 

[pma]

Topping support dept. wrote us, without any further explanation, that we should not use the RCA==>XLR adapter cable, but to use only the RCA==>RCA, or XLR balanced source with both + and - branches. This concurs with my guess that the output is BTL and to get both branches working it needs the the XLR input with both signal polarities.

I have re-measured the B100 using the RCA-RCA cable. I had to use an USB-ISO adapter with the DAC to get good attenuation of mains frequencies then. The follow-up review is here:

Topping B100 RCA amplifier test review

With my stepped sine method, 0.8s burst + 0.5s interval, the amplifier maximum sine power was 54W/8ohm/1kHz without shut down and 94W/4ohm/1kHz with shut down and long time to wake up. The amplifier was hot in that last test.

The amplifier failed to reach Topping power specifications, so, according to my measures, it did not pass the test. The manufacturer should derate the power specs.

 

[ssn22]

I want to know if this verdict is final

 

[Sokel]

What is very useful to get out of these tests is that adapters,etc is a big no if not specifically stated.
Otherwise companies have to warn (some do) with BTL amps.

Also,with these kind of amps one has to be careful never to tie ground at any of it's outputs,so some complex schemes involving passive speakers and subs with high level connections have to be thoroughly tested first .

 

[capslock]

Topping support dept. wrote us, without any further explanation, that we should not use the RCA==>XLR adapter cable, but to use only the RCA==>RCA, or XLR balanced source with both + and - branches. This concurs with my guess that the output is BTL and to get both branches working it needs the the XLR input with both signal polarities.

I have re-measured the B100 using the RCA-RCA cable. I had to use an USB-ISO adapter with the DAC to get good attenuation of mains frequencies then. The follow-up review is here:

Topping B100 RCA amplifier test review

With my stepped sine method, 0.8s burst + 0.5s interval, the amplifier maximum sine power was 54W/8ohm/1kHz without shut down and 94W/4ohm/1kHz with shut down and long time to wake up. The amplifier was hot in that last test.

The amplifier failed to reach Topping power specifications, so, according to my measures, it did not pass the test. The manufacturer should derate the power specs.

There is some logic to not using a proper balanced input circuit: lower noise (to achieve the SINAD crown) and lower BOM cost.

Thanks for retesting and telling us. 8/(8+13) = 61.5% duty cycle. For how long did you sustain the 54 W? How long until it shut down at 94 W. Was with the heat from the 54 W test still there?

So maybe my amp was a bit dogdy, giving up its ghost at 33 W which is about the same as 54 W at 62% duty cycle.

 

[pma]

The step bursts are 0.8s long and their amplitude increases gradually. It shut down after the previous sequence

How long until it shut down at 94 W.

The whole sequence takes about 2 minutes 20s if completed. The amp did shut down somewhere near 2 min.

54W/8R is the clipping point, so 54W was there for 0.8s and with the previous sequence again about 2 mins.

I think that 54W/8R and 94W/4R are close to @amirm measurements in post No.1.

Just checked and he got 50W/8R and 86W/4W. Both mine and his measurement tells that the amp does not meet the company rated power specs.

 

[capslock]

ok, many thanks. I didn't register the 8 R. So with that kind of a curve, the 60% duty cycle is only reached towards the end of the sequence.

 

[pma]

Yes. The sequence level increase is logarithmic. (but it keeps the 0.8/0.5 ratio for all the steps)

All, I apologize for the first review with the only half of the amp driven. I did not have an idea that it is a BTL and that the input is not an opamp differential amplifier, but direct drive of 2 amplifiers. It is inferior with respect to CMR and CMV. I just used the RCA-XLR setup recommended by Hypex/Bruno to minimize RCA cable common mode interference. I hope now it is OK, but please note I had to use the USB isolator for the DAC to get the clean noise floor and to avoid usual ground shied current issue.

 

[misterdog]

So Toppingate is not as bad as dieselgate (VW emissions scandal) as first reported.

I would reccomend consulting the manufacturer first before making erronious claims on a public forum.
Perhaps @amirm could remove all the posts with erronious measurements.

 

[misterdog]

I wish I had seen this yesterday, before I ordered a pair after they went on sale at Apos. I'm hoping you just got a bad unit. Since I already have them on order, I'll try them out. They will be pushing my tweeters in an all active system, so it is less likely I will run into any issues.

You should be ok now, some new science has been unearthed.

 

[pma]

I would reccomend consulting the manufacturer first before making erronious claims on a public forum.
Perhaps @amirm could remove all the posts with erronious measurements.

I agree, but needed to find the reason and the circuit connection myself. Topping did not share any technical information, just said

We found that the connection here is not quite correct. The B100 has RCA inputs. Please use RCA connections or please use a balanced output device to connect to the B100.

after we already found what to do. This is a very different approach from Hypex, Purifi and Soundimports support, where technical communication is possible.
And there is a warning for those who have only RCA output, because 3-wire RCA-XLR cables are often recommended here to avoid or fix the ground loop issues. Everything bad is good for something.

 

[MAB]

I agree, but needed to find the reason and the circuit connection myself. Topping did not share any technical information, just said

after we already found what to do. This is a very different approach from Hypex, Purifi and Soundimports support, where technical communication is possible.
And there is a warning for those who have only RCA output, because 3-wire RCA-XLR cables are often recommended here to avoid or fix the ground loop issues. Everything bad is good for something.

I find your test very helpful. More so than Topping’s documentation. Many people will buy this and never achieve the stated performance (especially due to grounding). In most cases inaudible. You showed how the end user needs to implement to get the max performance. Even then falls short of the claimed specs.

 

[misterdog]

Many people will buy this and never achieve the stated performance

As stated by Topping, or PMA measurement suite 1 or suite 2 ?

Or Amirm even..

 

[somebodyelse]

Topping support dept. wrote us, without any further explanation, that we should not use the RCA==>XLR adapter cable, but to use only the RCA==>RCA, or XLR balanced source with both + and - branches. This concurs with my guess that the output is BTL and to get both branches working it needs the the XLR input with both signal polarities.

That really ought to be emphasised in the documentation because it won't work properly with some varieties of balanced outputs, as you discovered. Might have a Pin 1 problem too?

 

[EddNog]

So Toppingate is not as bad as dieselgate (VW emissions scandal) as first reported.

I would reccomend consulting the manufacturer first before making erronious claims on a public forum.
Perhaps @amirm could remove all the posts with erronious measurements.

Or perhaps @AdamG

 

[MAB]

As stated by Topping, or PMA measurement suite 1 or suite 2 ?

Or Amirm even..

All.

Unless you are adept at tracking down ground issues in your system.
And are 100% aware of your system's I/O implementation as PMA found. How many people will be using the wrong cable or adapter is unclear. Topping not helping users figure this out with their SINAD-intensive documentation.
I'll leave the rated power alone, it is perhaps the least important part. But for sure when users see their amp oddly shutting down, PMA's observations are extremely useful.

Edit: typo

 

[AdamG]

Or perhaps @AdamG

I think it’s better to leave the posts as they are. People can read through and discover the errors and mistakes made. Deleting posts typically has more of a disruptive impact on the conversation flow. Of course I could be wrong here. But my gut instinct is to leave it up and let the readers follow the process and conversation to its conclusion.

 

[pma]

My 1st test is perfectly valid in case that someone used the 3-wire RCA to XLR cable to fix the ground loop issue, as it is often recommended here at ASR. Topping does not give any warning that such adapter cable is impossible to be used. They also do not disclose that there is the direct BTL topology. So the review is valid for that kind of connection and the schematics is in the review. The measurement with this connection is not an error, it is what it is.

The 2nd review utilizes the amp topology properly and is in conformance with Amir’s results, so it is an independent verification. Both Amir’s and my review show that Topping B100 is unable to yield the rated power at THD+N<1% into 4ohm, as it shuts down before reaching the rated power. If the rated power is reached into 8 ohm is questionable, as above the knee at 54W it is difficult to make any reliable reading. And it is only this 2nd review that is now directly accessible from my HomePage.