Power Amps with High Current or High Damping

The ability to double an amps power as the impedence of a speaker is halved is an example of a high current amp.

High Damping factor is inherent in Icepower class D amps. My small Rowland 102 has DF=4000 at low frequencies and about 1000 at 1kHz. I said "inherent" because always two of four Mosfets are ON shorting load between power and GND. Feedback also helps a bit.

In traditional amps you can get high DF thru deep negative feedback which is really bad because of increased TIM distortions.

I believe that if you see spects like DF=5000 or THD=0.001% then something else has to give and it's usually the sound.

Very high DF is not needed since inductor in series with the woofer (about 0.08 Ohm) limits DF to about 100. At 20 kHz you'll get similar limitation by cable's inductive impedance.

Many people look at DF as a measure of the quality of the amp. I see DF as potential problem. Deep negative feedback caused TIM distortions make unpleasant sound (exaggerated odd harmonics) or even moments of silence after fast transitions (charge trapped at the output transistor's junction after saturation). This moment of silence is not audible (our brain fills the gap) but is fatiguing.

Whatever is going on here, damping factor (which is over-rated) has little to do with it. The speaker has a moderate impedance without a lot of phase shift- a tube amplifier as commented in the reviews can work with it just fine. In fact you don't need a lot of 'current'- you simply need the power to make it play since an 89 db efficiency is going to need some power behind it to make it play to convincing volume in a moderate (say 17'x25' room), depending on the program material.

So there is some difference between the two amps first mentioned that is not stated in the specs. It could be something as simple as reacting differently to the same speaker cable, which was not changed, at least so far as we know.

Hi Krell_man, this is a bit off the amp topic but I wanted to respond to your thread regarding the Wadia 581 SE vs "Accustic Arts" mainly because I was all excited after reading your thread.

So I contacted my friend and made a trip over to his place last nite for a listen.

He uses a pre now but originally had the Wadia connected direct to the amps as you currently do. He has Bryston 7 SST's mono's and Thiel 3.7's, he uses Elrod power cables.

1. My observation without getting into detail was the same as his, you really need a pre with this unit and that is why in the end he got one. The sound just does not compare without one.

2. I borrowed the unit, I hooked it up direct in my system. I then hooked it up with my pre. which in my opinion was much better but sorry it still does not compare to my current set-up, not even close.

I was all excited about this but in the end there was nothing I liked better period, if I had I would have commented. I fully understand your comments and reference made to the "AA" dac and transport you had, I fully understand the price difference with my current set-up also but honestly only one listen and the comparison conveys money well spent on my part.

My friend is actually going to be getting a 781 latest version to compare so he will let me know if it's worth the drive. My friend also heard my set-up during the comparison and mirrored my conclusions but of course it's allot more $$$$$$$$$.

He asked me to ask you if you can hear your unit running, I could hear his and during quiet passes this distracted me. I was told his first unit was much louder and took it back do to this for an exchange. I hear absolutely nothing with mine even with my ear right up close.

I currently have an Esoteric P01 unit with clock on loan but is just in the process of being broken-in, big! big! dollars and this thing is really noisy compared to mine, I had to put it in anther room as it was distracting me from my listening, what the heck is going on these should be silent.

David,

For some reason, Wadia units take a few days to reach their characteristic sound. This has been commented upon extensively, and it includes everything in their line. I find a cold player to be unlistenable until at least 24 hours. Some claim it takes 7 days. Bottom line is that you should ask your friend to keep it in your system for a week without touching the power or interconnects. It may still not be your thing, but I think it is hard to do a quick A/B comparison.

The Esoteric P01 transport is a real statement piece.