High end Class D amps?

There are class A/B amps that have been designed to output very high current levels at the expense of cost and weight, and thus far, class D designers have chosen to focus more on the mainstream market where current demands are not as extreme. But this has nothing to do with EPDR.

I'll grant you that there may be limitations in the number of output devices that can be paralleled and still maintain appropriate switching speeds. With current output devices, this may limit the maximum current that class D amplifiers can deliver to less than is possible with a class A/B design. I have not tried to design a class D amplifier myself (other than using an off-the-shelf module), so I don't fully appreciate the limitations, But I think the potential is still quite high even with current devices. 

For most reasonable speaker loads, the current demands are well within the capabilities of mainstream class D amplifiers, such as those built using the Purifi, Hypex, and ICEpower modules. The Purifi module, for example, can output 25 amps before the current limiter will kick in. Obviously, this still requires that you have a power supply that can deliver this level of current, as it does with a class A/B amp. 

About the IceEdge 1200 AS1 modules in the PS Audio and the amps I made last year: I measured them at 2 ohms of 1000 watts......200 watts below what it does into 4 ohms......yet Michael Fremer says it drives the Wilson’s very well? I have not read the review yet. OH NO, this cannot be. George will never talk to us again. Michael just destroyed his "class D cannot drive Wilsons" nonsense that he as been spouting for years.  He screams.....but it does not double its power into 2 ohms......it cannot possibly drive a Wilson......ha ha ha......So, i guess 1000 watts into 2 ohms is enough after all.

Is there a moderator in the house?

Hey moderator, this @georgehifi character pollutes every single Class-D thread with tons of messages making a claim that is totally wrong. This must be the 3rd of 4th thread just since I joined.

@georgehifi,

I am not going anywhere.

Your repeatedly attempts to use EPDR shows you have no idea what it means and how it relates to amplifiers, and I would say contrary to what Atmasphere said, it does not apply at all to Class-D as the FETS in Class-D do not operate in the linear region, hence the phase has no bearing on the thermal loading of a Class-D amplifier.


As well, Class-D amplifiers may not double in power intentionally, as they may intentionally current limit. That is not a bad thing and has no impact on sound quality if you are not driving into clipping and there is no stability issue. Your repeated attacks against something you clearly don’t understand really needs to stop.

It’s rare that someone will state so clearly that the don’t understand what they are arguing about. As a monument, I will place this here.

Hint for George, EPDR is NOT a measure of current loading. It is a measure of equivalent thermal loading. Unless the load is a resistive only, this will ALWAYS happens somewhere other than where the current is at a maximum.

georgehifi8,069 posts12-15-2020 6:09pm

George - You’ve brought up this notion of EPDR in several class D threads, but haven’t explained how it relates to class D.

It relates to any amplifier seeing the low EPDR loading which demands extra current to be delivered from the amp, which Class-D’s don’t do as well as good linear Bi-Polars can.

I see a slight problem in Michael Fremer’s review of the PSA amps...he and Paul McGowan happen to be very good friends...so..for reality’s sake...I would take that review with a grain of salt.