terryforsythe
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EDIT: Deleted because I was responding to a post more than a month old.
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Topping B200 Monoblock Amplifier Review
- Thread starter amirm
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No problems
Topping plays with impedances to reach those SINAD values.
On this amp the input impedance is 10Kohm which is too low. FR will be affected if preamp output is not extremely low.
For high end speakers that dip its impedance below 2 ohms on some frequency the limited current of this amp will also affect the FR.
So, component matching must be heard before guiding the purchase only on this measurements
On this amp the input impedance is 10Kohm which is too low. FR will be affected if preamp output is not extremely low.
For high end speakers that dip its impedance below 2 ohms on some frequency the limited current of this amp will also affect the FR.
So, component matching must be heard before guiding the purchase only on this measurements
misterdog
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Same as the Gryphon Audio Essence monoblocks at $ 46,000 /pair.
Sidebar 1: Specifications
Description: Solid-state, mono power amplifier. Input: 1 balanced (XLR). Output: 2 pair custom, gold-plated binding posts. Input impedance, balanced (20Hz–20kHz): 10k ohms.
Though if you buy the stereo version the input impedance is 20Kohm the same as the Benchmark AHB2,
maybe they're 10Kohm per channel.
10KOhm input impedance is not very low. Even with a preamp with an output impedance of 600Ohm (which *is* high) the ratio would be 1̶5̶0̶, EDIT: 16.7 (about 15) which is absolutely fine.
However, the "low" input impedance is not the only reason of the high SINAD of this amplifier. Hypex and Purifi modules, without a buffer, have a lower SINAD and also lower input impedance. Not that these differences matter much in practice.
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AHB2's input impedance is 50KOhm.
Topping products sound thin and bright due those impedance tradeoffs.
I had the Topping pre90 and the Benchmark LA4 that I also had and the AHB2. The Benchmark sounds a lot better on every regard even as measurements favor Topping.
The cause is the input impedance that affects the FR
For making Topping products to sound good component match is imperative.
That is my experience after believing blindly the measurements posted on this site.
Jimi Floyd
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I am sorry to be "that guy", but the ratio would be 16.7, not 150.
Absolutely right, I was tired. Anyway even "about 15" is above 10 which should be fine.
Sokel
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It's not only the low input impedance that makes nice charts, it's the low input impedance along with low gain.
It's the combination that does the trick.
Topping even did one (don't remember which one now) with almost negative gain at one of its settings
That would be the B100 with -0.1 dB gain.Topping even did one (don't remember which one now) with almost negative gain at one of its settings
It really isn't. Unless your DAC/Preamp is running output impedance exceeding 500ohms - in which case it is this device which is at fault.
The only thing I can think of for this to be true is pairing it with a "passive pre-amp". But why would you want to do that?
Unlike loudspeakers, input and output impedance of amplifiers are usually weak (and smooth) functions of frequency. They don't usually affect the system frequency response much, even when the ratio of the pre-amp output impedance to power amp input impedance is low. All it causes is signal voltage attenuation.
And even in that case, 600ohm (which I gave an an extreme example) isn’t too bad. Into a 10KΩ Z in you would still get a factor of 16.7.
Also, it really depends on the type of load as well. For example, D90 (first gen) XLR Z out = 200Ω while Pre90 D in = 2KΩ but in general this gives only a loss, not a bass light response.
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Correct - low input impedance will have no impact on frequency response (it will even improve it if there is any stray capacitance on the input)
Very high output impedance can impact frequency response (rolloff of the treble) if the interconnect has high capacitance - though I think only inaudibly with typical interconnect at sensible lengths.
The typical hand wringing over component compatibility is really overblown. The vast majority of devices have sensible output and input impedances - and the vast majority of the rest are not bad enough to cause audible problems.
Yup.
Well, this was my idea when I built my system. The interconnect from my D90 to the Pre90 is about 40cm and I confectioned it myself with a shielded two wire cable, I do not remember the capacitance but it was quite average for this type of interconnects. I have a longer (unbalanced) run (almost 3 meters) of that cable to the plate amps of my two subs, but since these only operate on a limited frequency range (from about 20Hz, and a 4th order rolloff at 64Hz), any difference there is also in the realm of the inaudible (and would be swamped in the variation of the frequency response of the sub themselves, which are ripoles). The (balanced) run from the Pre90 (Z out is 40Ω IIRC) to my Purifi-based power amp build (I used the Neurochrome buffer: Z in is about 48KΩ, I guess 24KΩ for balanced) is shorter, and with an impedance ratio of about 600 I frankly do not have to worry.
True, but most people are also in the extremes: they other obsess too much, or they just do not care or are not aware of what it actually is. The latter usually fall prey of snake oil salesmen, which often sell defective-by-design or badly matched components to "tune" the sound.
misterdog
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Don't believe the first thing you see on the internet.
Benchmark AHB2 Review (Updated Measurements)
Audio Science Review (ASR) Forum
https://www.audiosciencereview.com › forum › bench...
29 Dec 2023 — Absolute maximum input voltage = 30 VDC; Absolute minimum input voltage = -0.3 VDC; Input Impedance = 20 k Ohms. Protection Circuits. Fully ...
How that appears when in Amirs article it states 50KOhm.
misterdog
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Topping even did one (don't remember which one now) with almost negative gain at one of its settings
Topping B100 at 0Db gain setting powering my Quad 989 ESL's.
Sounds mighty fine, though I have 15V output available from my Topping Pre90.
Yes it runs out of steam at C 80dB at 2M listening seat.
Noise = < 0.3uVrms..
That's less noise than from my E70 DAC, albeit I'm essentially using it as a unity gain buffer not as a power amp.
Topping even did one (don't remember which one now) with almost negative gain at one of its settings
There is nothing wrong in having a power amplifier that does only a current gain and no voltage gain, so a current amplifier. In fact, from a conceptual point of view separating voltage and current gain makes sense — like the MoFo, the F4, or Andrea Ciuffoli's Power Follower...
Roberto
Sokel
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Any gear with very special needs is broken from a practical standpoint in my book.
Agreed, it has other modes that do have gain, still low though from a traditional standpoint.
It shouts "I'm chasing SINAD" from afar.
After all the definition of the perfect power amp is "a wire with gain" .
And comparisons must be made under the same conditions, covering all traditional sources.
None of the weird designs as the above passed the time test.
Even the smart, easy to drive musical-fidelity 750k supercharger (meant to put after a power amp and with an easy 50 Ohm input impedance) remained an obscure concept, even if it worked and measured fairly well.
The later had huge gain though and lots of power to drive anything with no special demands under 2 Ohm or so.
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