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Why did Class H amps never really catch on?

dfuller

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Seems like they're a general improvement over traditional single-rail Class AB as well as Class G in terms of both efficiency and performance, but they never really seem to have caught on for whatever reason outside of some live sound sub applications. Any reason they seem to be less-than-common outside of the AHB2 and some BASH plate amps beyond "well Class D exists and is good enough"?
 

gonzoucab

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i hope topping make a version of this
 

SmCaudata

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Emotiva XPA-2 is a class H. Class H adds cost and complexity. Also, in the audiophile world (where people will actually pay) people seem to want the old style power supply. Now that we have sites like this, which would help class H power, we are benefiting from lower cost class d.
 

DonH56

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I think what Emotiva calls class H is really class G, not completely sure, but that is what Keith described at one time. My Emotivas are Gen1 so pure class AB.

I do not know, not my day job, but as mentioned above a linearly tracking (class H) power supply is a much more complex beast than one that "just" switches the voltage rails (class G). It is a lot harder to design and make stable, both in fundamental amplifier stability and in keeping supply modulation under control when the supply is intentionally varying (bias circuits, not just gain stages, are more complex). But switching the rails also leads to issues with bias stability, amplifier stability, and need for careful transient control, so class G is not a panacea. At the end of the day, class D offers higher efficiency and a more straight-forward design, albeit with its own set of challenges and tricks. And the "linear analog" crowd probably wants "pure" class AB so marketing gets involved...

My 0.000001 cent (microcent) - Don
 

dougi

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H-713

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Sure it didn't catch on... the Crest 4801, 6001, 7001, 8001, 9001, 10001, 10004, CA4, CA6, CA9, CA12, CA18, just didn't exist. Hell, Crest, QSC, Camco and a whole bunch of others just don't exist.

Class H caught on in the pro world, but big amps really aren't that common in an audiophile setting. Usually you only see Class G and Class H in amps that are more than 300 WPC.
 

DACslut

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I still have a 20+ yr old "Class H" Technics SA-DA10 receiver that weighs 28 lbs and literally gets hot enough to fry an egg on. Apparently the fan operation is not temperature but load dependent. Other than being an obsolete Home Theater relic, it remains an excellent sounding unit.

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Jim Matthews

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I was under the impression that cost to manufacture and mean "time to failure" drive most engineering choices. Few consumer products are advanced beyond what is necessary to generate sales.

The precipitous rise in home computing power is a notable exception.

Countertop induction cooking is another.
 

Head_Unit

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I'll be damned, I didn't know those were Class H, but it says so on the spec sheet. I had IIRC a 10001, OMG 135 pounds or something, wish it had been made of gold. Built like a tank.
 

pma

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I have been challenged by class A+ principle rather than class H. Class A+ is the way how to completely avoid crossover and switching distortion though keeping the radiated heat at acceptable level. I think that John @restorer-john might remind me if there was a commercial amplifier (Crown? edit: Technics SE-A1 ) based on this principle.
X1 and X2 are low power class AB with high voltage supply rails. X3 is a class A power buffer with low voltage supply rails. rail+ and rail - are floating at Vout +/-10V.

classA_plus_sm.png
 
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Goodman

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I will be looking forward to your experiment and findings. In the meanwhile I have two questions . Which Crown amp are you referring to? Is it any good for Hi-Fi use? Also: does the Quad (405-606) dumping circuitry have any positive affect on this unwanted switching distortion?
 
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