Topping B100 Amplifier Review

[pma]

... and why was the complex load part of the review omitted for the B100?

//

I tested with 4ohm//47nF and it was stable, no signs of oscillations. Again, based on the protection behaviour and no intent to destroy the amp of my friend, I did not push the more difficult load. I make torture tests on the amps that I own, or after an explicit negotiation with the amp owner.

 

[somebodyelse]

If they don't use a proper subtractor/rebalancer circuit right at the input of the B100 it simply does not comply to most basic requirement of balanced connections: you must not make any assumption about signal symmetry, or in other words, common-mode voltage shall be ignored and shall not have any impact on performance.

Schiit do the same with the Vidar 2. It has RCAs for stereo and an XLR for mono, with this hint it in the manual:

2 Connect a balanced source using a
high-quality XLR cable. Important: it must
really be balanced for maximum power.

There are a couple of FAQ entries about it too:

But what if I have insanely inefficient speakers and I wish to suffer hearing loss in the future?
Then use two of them as monoblocks. Of course, to do that, you’ll need a preamp with a real balanced output, like Freya. Plug a single balanced output into Vidar, and it turns it into a 400W/8 ohm mono amp.

Wait. How does the monoblock mode work?
It’s not a mode. It’s just the natural result of driving each channel with one half of a truly balanced signal. That’s why you need a preamp with balanced outputs.

They've been very good at avoiding calling it a balanced input.

 

[TNT]

I tested with 4ohm//47nF and it was stable, no signs of oscillations. Again, based on the protection behaviour and no intent to destroy the amp of my friend, I did not push the more difficult load. I make torture tests on the amps that I own, or after an explicit negotiation with the amp owner.

This was not aimed at you but rather the discussed review at page 1.

//

 

[totti1965]

But running a direct coupled input (no capacitor), connecting a source with an offset and allowing a constant DC at the output is not good for loudspeakers (voice coil woofer displacement, distortion, heating and potential demagnetization of the driver magnet in the long term).

Is it this, what we would do, if running a modern chifi-Desktop-DAC with the B100?
Do you have any amp Suggestions for avoiding the problems you mentioned?
Vintage would be no problem for me.
I don't hear loud music and I am only about 5 foot away from the 85 dB / 1m speakers.

 

[MAB]

Though my 5 email questions to them over the last few years have been responded to within 2 days.

How many times have you contacted them ?

It has taken 7 weeks thus far to get an energy performance certificate for my mothers flat, each of the other 34 flats are all rated 'C'.

All this Topping bashing seems a little disingenuous to me as a happy Topping customer so far.

Wait until you have a real issue. I’m the proud owner of a PA5, which was a lemon, and had a really weird and highly unprofessional experience with some of the most bizarre after sales service ever. Included ghosting me for months, along with many other people, I’m not unique. All over a genuine lemon. So your 5 questions answered seems like an outlier. Did you have an actual issue? They make amps and DACs, there should be no confusion on operation. It’s not like their gear has any features. Did the manual not suffice?

 

[restorer-john]

It’s not like their gear has any features. Did the manual not suffice?

It was likely needing help interpreting the flashing single LED fault/failure codes... /s

 

[MAB]

It was likely needing help interpreting the flashing single LED fault/failure codes... /s

You are slaying with humorous truth today...

 

[Old_School_Brad]

However, this warning about Hypex amplifiers on the Audiophonics website made me wonder:

„This amplifier has no decoupling capacitor and therefore lets the DC portion of the signal through. Make sure that there is no DC component at the output of your source. The module's DC protection kicks in at 12 VDC, which is very liberal.“

The Wiim Pro Plus is a well-made, high-quality product. If you’re still worried about DC to the amplifier, you could configure a steep high-pass filter at 20 Hz or below using its DSP, which is a good general practice for DSP setups. I’ve done something similar with my miniDSP as well, just as a precaution. Since my entire family uses the main system and browses through everything on Spotify and YouTube, having a "rumble protection filter" is essential to ensure the speakers are protected from unintended signals.

This assumes the DC is coming from upstream devices, but the amplifier itself could also produce DC at its outputs.
John has already explained the effects of having constant DC in speakers.

 

[pma]

I sent this https://pmacura.cz/FCT/topping_b100_rca.htm
to Topping support with a note that the amp failed to fulfill rated power specifications. Let’s if I will receive an answer.

 

[capslock]

Going back a few pages, there was a discussion if this amp is really class B (no idle current in the output stage) or rather class AB with a low idle current. Either way, it would be interesting to see distortion products at very low out (0.5 or 1 W). Unfortunately, my B100 is damaged and was returned. I am still waiting for a reply whether I can still cancel the other order that I placed about three weeks ago. If it gets here, I may try to measure that.

Edit: just got word that they will stop the shipment

 

[miero]

@capslock Did you receive a refund or will there be a replacement/repair of the damaged amplifier?

 

[miero]

I sent this https://pmacura.cz/FCT/topping_b100_rca.htm
to Topping support with a note that the amp failed to fulfill rated power specifications. Let’s if I will receive an answer.

Perhaps we (or EU/US dealers) should ask them to declare a power rating that complies with the FTC Amplifier Rule.

 

[KSTR]

It's how they found that extra dB of SINAD

Schiit do the same with the Vidar 2. It has RCAs for stereo and an XLR for mono, with this hint it in the manual:
"Connect a balanced source using a
high-quality XLR cable. Important: it must
really be balanced for maximum power."

There are a couple of FAQ entries about it too:
"But what if I have insanely inefficient speakers and I wish to suffer hearing loss in the future?
Then use two of them as monoblocks. Of course, to do that, you’ll need a preamp with a real balanced output, like Freya. Plug a single balanced output into Vidar, and it turns it into a 400W/8 ohm mono amp.

Wait. How does the monoblock mode work?
It’s not a mode. It’s just the natural result of driving each channel with one half of a truly balanced signal. That’s why you need a preamp with balanced outputs."

They've been very good at avoiding calling it a balanced input.

A precision (low noise, low distortion, high CMRR and excellent output symmetry) rebalancer circuit with high-Z input takes three opamps and some Rs and Cs. Gain (like 10dB, 20dB and 30dB) is switchable with a single resistor, and unbalanced input can be connected directly. The 4th opamp (when using two duals or one quad) can be used for a DC servo.

Proper analog audio circuit design is a lost art, it seems, and designers don't grasp even the most elemetary concepts anymore... it would suffice to read the Wikipedia entry about "balanced audio", quoting:
"A common misconception is that balanced audio requires the signal source to deliver equal waveforms of opposite polarity to the two signal conductors of the balanced line. However, many balanced devices actively drive only one side of the line, but do so at an impedance that is equal to the impedance of the non-driven side of the line. This impedance balance permits the balanced line receiver (input stage of the next device) to reject common-mode signals introduced to the two conductors by electromagnetic coupling."

 

[pma]

This would work very well as a simpler option

https://www.ti.com/lit/ds/symlink/opa1632.pdf

with some penalty of lower input impedance. However, their SE input has 5kohm, so it should be possible to make same input impedance. Maybe some of their designers reads here .

 

[pma]

distortion products at very low out (0.5 or 1 W).

I did that, very low, unfortunately the plot not archived.

 

[KSTR]

with some penalty of lower input impedance.

Lower impedance and higher noise and spoiled CMRR with even the slightest source impedance mismatch.
But yes, a FDA would be one way to make it much better than it is currently, or just the 2-opamp equivalent (known as "Superbalanced Input" by Doug Self).

 

[pma]

Perhaps we (or EU/US dealers) should ask them to declare a power rating that complies with the FTC Amplifier Rule.

It is IEC 60268-3 here in the EU.

 

[capslock]

@capslock Did you receive a refund or will there be a replacement/repair of the damaged amplifier?

That is amazon (actually, a marketplace seller from China). I haven't seen amazon do a replacement in years. They simply refund and tell you to orde anew. If the price has increased it's your problem (not that I would want another until, at minimum, the firmware is fixed to avoid permanent damage).

If they ever do B100 II, they should use a larger internal heat sink and either include a temperature controlled fan or switch to vertical fins. I don't see how the horizontal fins on that miniscule heat sink they use today can do any convection cooling.

 

[capslock]

I did that, very low, unfortunately the plot not archived.

So also at -140 dB? I really wonder how they do that with no or a very small idle current. No amount of feedback should be able to iron out heavy crossover distortion.

 

[pma]

No, I cannot measure that low. Just down to -130dB. Anyway, I find such race pointless, bringing nothing but issues we can see here. But it sells, the SINAD sells to certain group of customers, regardless other parameters.