Topping B100 Amplifier Review

[Bleib]

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

Heard a bit on this forum that LA90D is not superbly reliable. I'd go with the monos, probably end up adjusting volume through something with a remote anyway

 

[Deleted member 72219]

Heard a bit on this forum that LA90D is not superbly reliable. I'd go with the monos, probably end up adjusting volume through something with a remote anyway

L70 works great for this, with its remote-controlled resistor ladder volume control and 12V trigger out. ;-)

 

[Mort]

LA90D had reliability issues and are also (perhaps unsurprisingly) much cheaper now used. One used on Amazon for under $500

If I could get a used reliable LA90D for under $500, that would be much preferable than new b100s for the form factor and volume control.

Eventually b100s will be available used and cheaper as well

 

[terryforsythe]

Eventually b100s will be available used and cheaper as well

A couple of months ago I saw Apos had a sale on the B200. $100 off if I remember correctly. So, if interested, keep your eye open for sales. I'm hoping on Black Friday.

 

[ryanmh1]

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.

Benchmark has a calculator for this exact question on their website. It matches with manual calculations I've done before. Uncorrelated white noise effectively does not sum, if you don't botch up the gains. Overall SNR is, for all practical purposes, that of the lowest item in the chain. The worst case is two equal noise sources, which will cause a 3db degradation. 3 will lose you about 5db. This assumes, of course, SNR measured at clipping and both components clip at the same time. So your -100db 2V DAC into -100db 2V preamp into 2V clipping -75db amp will likely yield a -74.9db(ish) or better overall.

To relate to this amp, SNR will be that of the signal chain, since SNR is so high.

 

[Deleted member 72219]

So with E70 Velvet which is -131dB SNR for balanced output and L70 which is -138 SNR for balanced output with a pair of B100s, the net system SNR is -131?

-Ed

 

[terryforsythe]

So with E70 Velvet which is -131dB SNR for balanced output and L70 which is -138 SNR for balanced output with a pair of B100s, the net system SNR is -131?

-Ed

It depends on what gain setting you have set for your B100. If you have it set to 20dB, it is going to increase the noise feed into it by 20dB. So, if -131dB noise is on the input signal going into the amplifier, that noise will be -111dB at the output of the amplifier. Then, add to that the B100's own internal noise, which will increase it, but not much given the B100's low noise floor.

 

[staticV3]

So with E70 Velvet which is -131dB SNR for balanced output and L70 which is -138 SNR for balanced output with a pair of B100s, the net system SNR is -131?

-Ed

Not that simple I'm afraid.

Depending on which gain you set the L70 to, which gain the B100 is set to, and how loud you're playing overall, the effective SNR of DAC+Pre+Amp will change.

 

[Deleted member 72219]

E70 Velvet set to 5V output
L70 set to Low Gain
B100s set to Medium Gain
All connected via XLR

-Ed

 

[staticV3]

E70 Velvet set to 5V output
L70 set to Low Gain
B100s set to Medium Gain
All connected via XLR

-Ed

E70V has 1.3μV(A) of self-noise.

L70 in Low gain (+6dB) will amplify that to 2.6μV(A).

L70 has 0.7μV(A) of self-noise on top.

Incoherent summing gives us 2.7μV(A) going into the B100 (no, you don't just add them )

B100 in Medium gain will amplify that to 8.9μV(A).

B100 has 1.0μV(A) of self-noise on top.

-> ~9μV(A) of noise on the B100 output.

At 4Ω, the B100 can output 100W max (=20Vrms), so the maximum achievable playback DR is 127dB(A).

That is, if you leave the L70 on max volume and attenuate using the DAC.

If you leave the DAC on max and attenuate with the L70, then SNR/DR should improve slightly.

 

[Deleted member 72219]

E70V has 1.3μV(A) of self-noise.

L70 in Low gain (+6dB) will amplify that to 2.6μV(A).

L70 has 0.7μV(A) of self-noise on top.

Incoherent summing gives us 2.7μV(A) going into the B100 (no, you don't just add them )

B100 in Medium gain will amplify that to 8.9μV(A).

B100 has 1.0μV(A) of self-noise on top.

-> ~9μV(A) of noise on the B100 output.

At 4Ω, the B100 can output 100W max (=20Vrms), so the maximum achievable playback DR is 127dB(A).

That is, if you leave the L70 on max volume and attenuate using the DAC.

If you leave the DAC on max and attenuate with the L70, then SNR/DR should improve slightly.

I have the DAC set to pure DAC mode and use the L70 for its analog domain, resistor ladder volume control.

-Ed

 

[ryanmh1]

It depends on what gain setting you have set for your B100. If you have it set to 20dB, it is going to increase the noise feed into it by 20dB. So, if -131dB noise is on the input signal going into the amplifier, that noise will be -111dB at the output of the amplifier. Then, add to that the B100's own internal noise, which will increase it, but not much given the B100's low noise floor.

That is not how this works. He was mostly correct, assuming SNR was measured at, say 5V output and the amp needs 5V to clip. Gain doesn't matter much to SNR (in this example). Yes, you gain up the noise, but you also gain up the signal.

Edit: I missed the preamp in there, but Staticv3 covered it. That adds a small extra hit.

 

[terryforsythe]

That is not how this works. He was mostly correct, assuming SNR was measured at, say 5V output and the amp needs 5V to clip. Gain doesn't matter much to SNR (in this example). Yes, you gain up the noise, but you also gain up the signal.

I wasn't discussing SNR. I was discussing just the noise content. But, I should have been more precise and used the absolute voltage level of the noise. Whatever is the level of the noise, the amplifier will amplify that noise according to the gain set in the amplifier. Also, the amplifier's internal noise will be added to that.

 

[usern]

What reliability issues of Topping amps are being referenced here? Some angry forum posts or actual failure data from Topping / sellers?

 

[Timcognito]

What reliability issues of Topping amps are being referenced here? Some angry forum posts or actual failure data from Topping / sellers?

Search Topping PA5

 

[Mort]

If I could

What reliability issues of Topping amps are being referenced here? Some angry forum posts or actual failure data from Topping / sellers?

Are those the only two options?

 

[amix]

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

I got Dynaudio Contour 1.3 SE speakers (6Ω, 85dB) and they are considered current-hungry, but I never really understood the ratio behind it. Your comment seems to point into this direction. However I don't understand "current [...] under 4 Ohm for most of their spectrum". Could you be so kind as to rephrase/explain this?

I had a Quad 306 power amp (2x50W with "Current Dumping") but never was really happy with it. Then I went for Fosi V3 monos with 2x 48V/10A supplies but if it sounds different, than it's subtle.

When buying an amplifier for this speaker, what would I look for?

 

[Deleted member 72219]

I got Dynaudio Contour 1.3 SE speakers (6Ω, 85dB) and they are considered current-hungry, but I never really understood the ratio behind it. Your comment seems to point into this direction. However I don't understand "current [...] under 4 Ohm for most of their spectrum". Could you be so kind as to rephrase/explain this?

I had a Quad 306 power amp (2x50W with "Current Dumping") but never was really happy with it. Then I went for Fosi V3 monos with 2x 48V/10A supplies but if it sounds different, than it's subtle.

When buying an amplifier for this speaker, what would I look for?

See the spectral impedance graph from Amir’s review; almost half the spectrum covered at or around 3.7ohms for LS50 Metas.

-Ed

 

[usern]

If I could
Are those the only two options?

You say Topping amp has reliability issues. What issues? Based on what do you say that?

 

[terryforsythe]

You say Topping amp has reliability issues. What issues? Based on what do you say that?

Search Topping PA5