AzRyan:

Maybe it's a breakthrough, but I notice the graph that's most common and would be most telling is omitted. Putting it simply, the output filter that all class D audio amps must have will typically cause them to have frequency response problems on difficult loads. This could be overcome if the load is known or complementary EQ is applied, but ironically the customers of so called hi-end products would likely be the most opposed to the concept of equalization.

It could also be avoided if the carrier frequency is much higher than the signal. Industrial drives use this to practical advantage in using a (typically) 5 or 10 KHz carrier with a 10-100 Hz signal while driving an inductive load.

The published graphs for frequency response on the ICE modules clearly show that this has not changed. Acoustic Reality asserts they've got it licked, but I don't see anywhere a response graph for 8/4/2 and maybe 1 ohm loads. I wonder why that is?

Now a ribbon setup like yours might be an ideal situation for a amp like this, but I find it humorous that, after pointing out for years how badly 'cheap' amps perform on difficult loads the new hi-end darling apparently exhibits the same Achilles heel.

Also an amp like this will put out about the same amount of musical power as a good 125 watt linear amp. This is because, by design, a class D amp has basically zero dynamic headroom. In theory it's no matter, since a class D amp can be so efficient and small, but the eAR is not really a super powered amp, particularly when the lack of headroom is factored in. It's not unusual for a 100-125 watt linear amp to have a dynamic output somewhere near 175 watts.

With the Newform R645s the eAR should clip somewhere around 113 db instantaneous peaks at 1 meter, or plenty loud but not outstanding. The R630s would be inducing clipping about 3 db lower.

This is OK if the room is pretty small, one listens at below reference or you can tolerate short periods of clipping, but I'd rather not. This is, for me, a very narrow margin.

I want to be very clear here - I want to like this technology. I think it has legs. I also understand electricity and I can extrapolate from that knowledge that there are potential problems. The switching module used in the eAR exhibits those problems. Acoustic Reality says it's fixed in their implementation, but have not released any engineering or test documents to prove it. This makes me suspicious.

Have a good one.


[This message has been edited by charlie (edited December 13, 2002).]