Power Amps with High Current or High Damping

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.

Hi Rob,

thanks for that info. I still have the unit, it was plugged in at 8pm. I did do some initial listening but it was really scary unlistenable and did not mention that. My friend mentioned the unit needed some time, he came by the next day arround 6 pm. for a listen and this is the time frame of our evaluation, so aprox. 22 hours at that time. I'm not trying to suggest that the unit is not good but it just does not compare to my current set-up and the sound comparison of it being on it's own compared to being in the chain with a pre, well the later being by far my preference. I'm not being biased either because I would be the first to admit and would be looking at making changes, even if it was close I would but it's not. The unit is currently still in my system, luckily for me my friend has left it with me as he has gone away until next week. I had the unit playing all day, just back ground music but it's just not in the same league.

This Esoteric is the VU version with 8N copper wire set with clock and yes it's a real statement! never mind the suggest list!!!!!!!!!! Where the heck do I put all these pces. I have to say my expectations will be very high once I do my listening mainly do to the cost factor. I had a Metronome Kalista Ref Transport only in my system but prior to having the Tube dac, what a pce of eye candy. I did prefer it slightly over my Oracle trans but not by much, the deal breaker was that it would not play cds that I have never had issues with in the past nor currently which I factored in along with the list of over $50K compared to $7,500.00.

Have you got your pces back as of yet? waiting to read your thoughts regarding the Karan 1200's.