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Anyone compared high end Class D power amps?

The noise could be the decider though, looking at specs (which I don’t claim to understand) it seemed that only amps with S/N ratios well above 100 were quiet enough for the speakers....

With 105dB/W efficiency it is a very tall order for any amp to be completely silent even if you are only say a foot away from the speaker and in a completely silent room...
It has nothing to do with the class of the amp. Most (to all intents and purposes all in fact) hiss comes from the amps input stage/s.

S/N ratio's have to be compared carefully.. you need to be "comparing apples with apples"! Is it stated as relative to the amps full power or relative to a specified power output?
With a 200W amp 100dB S/N relative to full power is a lot noisier than a 10W amp being 100dB S/N relative to full power! Are figures in fact relative to power or to voltage? Over what measurement bandwidth?
 
Steve, I’m sorry I really couldn’t say. Back in the day I sold my Naim amps in favour of Dynavector. Then I went beefy valves for a while. When I didn’t need their power I got a Sugden A21. Then, thanks to Peter Stockwell I bought the Amptastic Tripath amp for £100 and was a bit shocked. This lead me to Temple Audio. In short, the Bantam One is a great amplifier (and is better and nicer to look at than the mono blocks) but so is an Avondaled 250 IM(limited)E.

In short there’s no way of knowing without trying. System, room, taste dependent but having tried almost all flavours, I basically think a good amp is a good amp no matter the recipe provided it can drive your speakers. I would finally add that the Bantam and Khozmo are absolutely the last things I’d think of changing.
Thanks Alex - much appreciated. I will keep my eyes open a used one or may just splash out - I'm just curious about what a different amp might add..
Out of curiosity, was your power-amp-only a reasonable amount cheaper than the integrated amp?
 
With 105dB/W efficiency it is a very tall order for any amp to be completely silent even if you are only say a foot away from the speaker and in a completely silent room...
It has nothing to do with the class of the amp. Most (to all intents and purposes all in fact) hiss comes from the amps input stage/s.

S/N ratio's have to be compared carefully.. you need to be "comparing apples with apples"! Is it stated as relative to the amps full power or relative to a specified power output?
With a 200W amp 100dB S/N relative to full power is a lot noisier than a 10W amp being 100dB S/N relative to full power! Are figures in fact relative to power or to voltage? Over what measurement bandwidth?

Ok I get you. All I went from was manufacturers specs after hearing the amps. The quietest ones had higher S/N ratios as a general rule.
With even the best valve amps (most expensive) I could hear hiss from the listening seat c.5-6m away. With the Temple Audios I have now you can only hear a little hiss from the mid unit if you’re ear is a few inches away max....
 
MMM, class d doesn't stand for digital it was just the next available letter when the class was introduced. A true digital amp takes a digital input directly.
 
At the risk of going off-topic, because it's not class D, have you considered the Benchmark AHB2? Not to want to contradict our resident forum amp designer, but the other part of the S/N ratio problem is unnecessary gain. The Benchmark deliberately has a relatively low gain, because modern systems don't need it, and has 130dB S/N as a consequence.
 
A few points arising from recent posts...

There are no real advantages to monoblocks... It's an old wives tale.

Many of the Pass designs are likely to be unsuitable due to noise. Many of them use mosfets at the input stage which are noisy... Quite possibly not all but most of the ones I'm familiar with.

Most power amps have a gain of around 30dB. The majority of over sensitive ones are no longer made. Within the small range of differences in gain for a practical unit for home use the noise contribution of the input devices will be the most significant factor. The Benchmark apparently has sensitivities of 2, 4 and 8V for max output!
 
Most power amps have a gain of around 30dB.

Indeed so - hence why the Benchmark's lowest gain setting of 9dB (or so) is quite atypical. Even the 2V sensitivity setting only has 23dB of gain. Stereophile had trouble measuring it - its performance in terms of noise and distortion was on the limit of their Audio Precision test gear: https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

It might still not be the OP's cup of tea, but the measurements are impressive, and I doubt he would be troubled by hiss, even with 105dB/W speakers.
 
Indeed so - hence why the Benchmark's lowest gain setting of 9dB (or so) is quite atypical. Even the 2V sensitivity setting only has 23dB of gain. Stereophile had trouble measuring it - its performance in terms of noise and distortion was on the limit of their Audio Precision test gear: https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements

It might still not be the OP's cup of tea, but the measurements are impressive, and I doubt he would be troubled by hiss, even with 105dB/W speakers.

Oh it has impressive measurements and seems a very good amp! It just pushes the noise issue to the pre amp though!
 
Of the Neurochrome amps referenced previously, the standard through hole Mod86 can be built with 14dB gain and a specified noise/ hum level of 40uV unweighted, 32uV A weighted. The more expensive Mod186 or 286 reduces that to 28.5uV/23uV but with a minimum gain of 20dB.

My back of a packet calc makes the resulting noise level from the Mod86 c. 25dB at 1m with that sensitivity spec, which should be good enough.
 
Yebbut! Aren't you always advocating passive preamps, 'cos modern sources have such high outputs? In which case only the noise contributed by Mr Johnson ought to be an issue.

Not with such an insensitive power amp! That's the point... it needs more gain which must then come from an active pre amp...
The 2V setting may be usable with a passive but on quietly recorded material it may be necessary to use full volume.
 


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