Hey pal, back off on the engineer thing, I'm one too! I want to measure as much as I can becasue I want things to be right. Like Charlie, I don't completely trust my ears to get right. My tastes change from day to day too. There's just something about having a number to verify everything that alleviates this feeling though.

I looked at the pictures gonk provided and nice setup Charlie! I don't see myself doing something quite like that, but it sure is cool to see. I don't see a hometheater system of mine getting that powerful or blended in so much, but I do see it with my car. Drop a couple 12 or 15" subs into a well made vented box with 1000+ Watts and there you go.

I am an electronics engneer and an audiophile.

I want equipment that sounds good AND measures good. There is enough excellent equipment out there so I usually can have both. The sound requirement is paramount. The only engineers that expect measurements (of a piece of equipment) to COMPLETELY characterize a piece of equipment are those who do not understand the nature of music reproduction and the limitations of measurements.

Paul

I agree with you Paul. I chose my speakers because they sound very good. I want the measurements to help them sound the best they can, and how they are supposed to.

Well as others have pointed out it's not without issues, but within the constraints I have it works pretty well. I'm working to fix some of the more obvious and easily compensatable issues as soon as I can spend the time and $$$. I'll try to keep the link up to date as long as Gonk will put up with me. I expect to get good improvements with some aggressive acoustic treatments and crossover tweaks.

Thanks for the kind words!

Charlie

I agree wholeheartedly. The obvious extension of that logic is that I won't tolerate moving to a measurably worse piece of equipment just because someone says it sounds 'better'. If it measures roughly as well then I'll give it a look, listen and think about it.

Digital amps in their current state [AFIAK] still have some serious issues with difficult loads, as well as other less important issues. Once that gets sorted out the concept has obvious benefits that can be realized.

There's always going to be someone blazing the trail, and often they end up face down with a back full of arrows. I prefer to follow at a safe distance....

I'm in the process of verifing the measurement results on my HT as well, so once that is done I'll post results/link.

Acoustic Reality has a PDF file up now of a hi-fi mag review of their amp.

There are even performance data charts shown for those who think charts matter more than what it sounds like. Not that these people will probably ever actually TRY one of these amps to hear for themselves, yet they like to keep posting about the subject??

Anyway.. the -this is best amp ever made- review speaks for itself.

Again... sorry Outlaw to mention another company's amp, but the amp does costs WAY more than Outlaw's amps so it's no direct comp. IMO, and I originally posted about it here to prod Outlaw into looking into using these dig. amp chips themselves.
Hopefully it's at least on a short list of things they're looking into.

The ICEpower's exclusive modulation method (used in my eARTwo amp) seems to be the best chip to work from.

Jeff Rowland amps are actually going to be using this chip now soon (a major mainstream hi-end company).
Of course they are going to be even more costly than the eAR amps and doubtful they'll be any better as the eAR amps already use the best of the best parts, but it does help show there's certainly something to this chip as Rowland has been making world class amps for a long time.

Outlaw... please look into replacing your solid state amps for ICEpower based models in the future.

Smaller, cool running, much smaller/cheaper power supply watt for watt, and far cleaner more accurate output signal. Probably the closest thing to the purest amplifier goal - "Signal gain plus wire".

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).]

Man, I would love to be a fly on the wall with you two in the same room!

Charlie, I usually agree with your technical approach as I tend to think that way myself.

However, to play Devil's Advocate, I also agree that sometimes simply hearing (or seeing )seeing something perform you can sometimes find something unexpected. A perfect example of this is the good old Outlaw 1050. Its performance is routinely observed as outdoing its specs on paper. Whether it's truly outperfoming its stated parameters is not really relevant. What is important is that its perceived performance is (typically) grander than what one is led to believe simply by reading the numbers.

Anyway, as always, I enjoy reading your guys' posts. Since you both seem to come at things from different perspectives, a pretty balanced discussion (including both technical and practical) usually ensues and a lot of good information is disclosed. It gives others of us something to ponder and investigate further on our own, if we're so inclined.

Keep it up, guys!

Yeah, it's all fun and games until someone loses an eye....

I hope neither one of you are getting the
Red Ryder BB Gun for Christmas.