Power Amps with High Current or High Damping


A fellow Audiogoner and I have the same monitors. He's run into the same problem that I did when trying to fill a 14' x 35' room.

I found out, completely by accident, that when I replaced my Herron preamp and monoblocks (150 wpc) with a Karan integrated (170 wpc), the Karan solved the problem.

Though the wattage was similiar, the high current and/or damping factor of the Karan took a hold of the speakers and made them play whatever it was sending. The monitors are completely up to the task and never broke up.

Jim is trying to keep his cost for an amp that will control his monitors like this to around $3,000.00, give or take. He asked me about a McCormack DNA 225, but I don't know anything about McCormack amps.

I would like everyone's thoughts about the McCormack DNA 225 and suggestions for other amps that would fit the bill.

Thanks,
Chuck
krell_man
What is an example of "high" current (spec-wise) vs. not?
I'd like to know if my amp is high current.
I think that you are onto the correct parameter but in an indirect sort of way. Damping factor, simplistically, is the ratio of (real part of the) speaker impedance to (the real part of the) amplifier output impedance. Remember that speaker impedance is variable over frequency so DF does not remain 1 fixed #. Unless the power amp output impedance is very low & well-controlled (sign of a robust power supply, which makes the amp cost sky-rocket), the amp output impedance is also variable over freq. So, you have both numr & denr varying over freq! Often you'll see lower DF as you come down in freq (often amp spec sheets show DF at 1KHz) that read in the range of just 10. So, the very large #s you have cited from spec sheets are essentially meaningless - they are probably measured with a non-reactive load (which is not what a loudspeaker is!).

I believe that you improved when you switched to the Karan amp is the amplifier output impedance - I get this feeling due to your comment "Karan took a hold of the speakers and made them play whatever it was sending". When the impedances are correct in the amp-speaker interface this is what the listener usually reports back.
One of the possible reasons for this is that the Karan amp has a much better power supply (lower impedance) & probably has more # of power transistors in the output stage (lower impedance) &/or higher current power transistors (more current delivery capability).
Krell_man, curious was there a reason you didn't try any other amps in the Karan line such as the stereo amp, KAS 270 Dual Mono stereo pce that has a damping factor of 6000 and 270 watts of power @ 8 ohms. There is another member "Cenline" who is also using the Wadia but with the Karan amp above and seems to be very happy.

Thanks for the info. I have never tried Wadia, will have to try as a friend just got the same pce you have recently but I have not made it over to his place as of yet.

Who is the man and partner you made reference to that you have great respect for?

Interesting regarding Brian's comments to you but I would have to disagree with him suggesting the Tube Dac improvement wasn't worth the added cost over the MK4, I feel it most defiantly is.

Brian doesn't sell "AA" product anymore correct?

That being said I would agree with you that the cost once you add up things is up there and if the Wadia is that good then it would most defiantly be a no brain-er.

Interesting info.
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.