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Class A “class D killer” amplifier with THD less than -120dB
- Thread starter pma
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Sokel
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That's true,I had a look at my big one and the graph is not so encouraging.
About 40-50(?)% at low levels,even less at really low:
@LKA, do you have some personal affiliation with LeXan or H-ENG? If so you should disclose it.
It's great to see high performance class A/B or, (for that matter), class B amps. There are some of course, e.g.
Efficiency in case of home amplifiers, as @restorer-john points out, is no big deal per se, but these amp almost invariable require heat sinks and heavier power supplies, (if linear), that add to the cost and weight of final product.
It's great to see high performance class A/B or, (for that matter), class B amps. There are some of course, e.g.
- Benchmark AHB2
- Neurochrome Modulus-x86
- Topping LA90
Efficiency in case of home amplifiers, as @restorer-john points out, is no big deal per se, but these amp almost invariable require heat sinks and heavier power supplies, (if linear), that add to the cost and weight of final product.
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- Thread Starter
- #146
Yes, the plot has linear X scale, for the obvious marketing reason - not to enable the reader to read efficiency at low, usual listening power, accurate. Usual markerting tricks.
I still think an amp module like Hypex NCore NC502MP, with 2 x 500W into 4 ohms to drive anything, very high SINAD above 100, costing 750 usd in a small and light chassis, barely warm around 15W idle (IIRC), is simply an unbeatable value.
Absolutely true. An insane amount of clean power in a small package at a relatively cheap price. Nobody can argue with that.
- Thread Starter
- #150
Class D amplifiers have low distortion only to some 4kHz, because the distortion measurements with 22kHz BW are totally pointless and show nothing about distortion at higher frequencies. Their idle power consumption is often higher than that of class B and even class AB amplifiers. Their HF garbage at the output is horrible and not investigated yet if it is without any influence on speakers and audibility. They are just massively promoted and that is why they are so popular within unqualified audience. They will probably push out linear amplifiers, but just for the reason of their massive marketing and “political” support. Equivalent to electric cars not mentioning the planet waste pollution with hundreds of milions of waste batteries that cannot be disassembled with use of automation. Who cares, deserts and ocean will digest it, until this planet will be unusable for human kind.
Let's zoom in on the 50mW to 2W range shall we?
The efficiency plot is only one piece, like so many other specs. The efficiency of any amp goes to 0 (or below) at low to no power. It would be nice to compare the actual power consumption of comparable amplifiers, e.g. a 100 W class AB+G/H to a 100 W class D amplifier, from idle to full power. Preferably with a log x axis to highlight say the 10 mW to 10 W region where most amps probably operate most of the time. IIRC my Kill-a-Watt says my four-channel Buckeye NC252MP burns a few watts at idle where as my two-channel Emotiva class AB burns ~30 W or more, but I do not have a class G or H amp to compare (somebody want to loan me their AHB2? 
)
I am not sure why the rash of "class D killer" threads. My microsecond look says the "killers" are better at HF distortion in some cases, worse at lower frequencies, and are generally less efficient but I have not seen an actual power in vs. power out plot. I am with @pma, @restorer-john, et. al. that I would like more data, including actual noise levels in uV or whatever.
Other than anecdotal "I hate class D, because it's bad" posts I am not sure I have read an actual blind listening test showing comparable amps with inaudible'ish distortion are audibly different. My own tests were far too limited to be of value and were not blind. I was not expecting a difference and got what I was expecting, surprise, but expectation bias works both ways. I have no desire to "kill" any class; they all have their pros and cons, no need to kill one to highlight another ("You don't need to put out another's candle to make your own shine brighter" -- William Adam).
)I am not sure why the rash of "class D killer" threads. My microsecond look says the "killers" are better at HF distortion in some cases, worse at lower frequencies, and are generally less efficient but I have not seen an actual power in vs. power out plot. I am with @pma, @restorer-john, et. al. that I would like more data, including actual noise levels in uV or whatever.
Other than anecdotal "I hate class D, because it's bad" posts I am not sure I have read an actual blind listening test showing comparable amps with inaudible'ish distortion are audibly different. My own tests were far too limited to be of value and were not blind. I was not expecting a difference and got what I was expecting, surprise, but expectation bias works both ways. I have no desire to "kill" any class; they all have their pros and cons, no need to kill one to highlight another ("You don't need to put out another's candle to make your own shine brighter" -- William Adam).
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- Thread Starter
- #156
I see, but my question is different. Another try - if the rated power is 100W/4ohm, what is the harmonic distortion at 1kHz and at 20Hz?
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Are you asserting that the makers of Class D amps or modules have done no studies on the effects of the HF components on speakers, audibility, etc.?
Would you please provide some links to results of studies that prove the negative audible effects or harmful effects on speakers? Thanks.
Exactly! If you manage to put a class A/B into a well done composite configuration, it outperforms class-D in almost all aspects up to say 250 Watts output power!
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