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# Amp power ratings

If a an amp is putting out 100 watts at 8 ohms what would be a reasonable guess of power at 300 ohms or 600?

2.66 and 1.33 watts respectively.

se

P = V * V / R

use this to get the squared voltage 100 watts * 8 ohms = 800 volts^2

so P into 300 ohms = 800 / 300 = 2.66 watts

This is only true for an ideal amplifier, correct? In actuality, it might not put out anywhere close to the theoretical value.

Quote:
Originally Posted by OJNeg

This is only true for an ideal amplifier, correct? In actuality, it might not put out anywhere close to the theoretical value.

If it can deliver that rated power into 8 ohms, then it can definitely handle that much lower power into 300 or 600 ohms.  Extrapolating up for higher impedance, just assuming that the same voltage level can be reached (thus the current is less) is the conservative estimate.  If the output current is a limitation for 8 ohms, it might be able to handle a higher voltage into a higher impedance, so you might be able to get a little more than 2.66 or 1.33 watts respectively.

Indeed, with an 8 Ω load, the power supply voltage is likely to drop somewhat from the high current at the maximum output level if it is not regulated. The amplifier may also have some open loop output impedance, even if only a few tenths of an Ω. In any case, I do not think there are any 600 Ω headphones currently in production that can even handle 1.33 W in the first place.

Edited by stv014 - 10/30/12 at 3:48am

I've tried running my 300 Ohm HD600's off of this amplifier with no problems at all. Granted I don't listen super loud but it sounds fine to me. I still mainly listen with my headphone amp because I don't think the added power really made that much of a difference.

How much do you use of the volume control range to reach a comfortable volume?

Btw, driving the HD600 with over 0.2 W can cause damage according to the (german) spec sheet.

Edited by xnor - 10/30/12 at 3:56pm

It goes up to a max of 69. I usually listen between 20-30 depending on how loud the recording is.

Seems to be a clear case of overkill.

Quote:
Originally Posted by xnor

Seems to be a clear case of overkill.

It's the audiophile code. If something is good, more of it is better. And a lot more of it is a lot better still.

se

The whole thing was more of an experiment then anything.
If that is the Case my lyr should also be damaging it correct?
Quote:
Originally Posted by BMBROWN911

If that is the Case my lyr should also be damaging it correct?

The Lyr outputs 40 Vpp = ~14 Vrms, which is over 0.65 W into 300 ohms. So yes, if you turn up the volume you risk damaging your headphones.

"With great power comes great responsibility."

Edited by xnor - 10/30/12 at 5:25pm
I do not listen loud. Probably 7-8 o clock on the volume knob.
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