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What is the Sound of Impedence Mismatch?

As I understand it, you want your power amplifier to have an input impendence much higher than the output impedence of your preamp, at least 10x. Can anyone tell me what the sonic symptoms are of a mismatch? If I'm hovering around 10x, what might I hear that would indicate an impedence mismatch as opposed to, say, a preamp that is simply too bright or whatever?
drubin
aball
2,018 posts
 
11k would be right (provided Pass did not do something unconventional but I cannot think of what that may be). 1700 ohm preamp is on the high side-11k for an amp is not too bad. If you could hook up your system to an oscilloscope you could find out for sure. Mismatches like this show up as a quasi-sinusoidal wave in the pass band (instead of a totally flat one) which causes excess distortion to the signal - easy to see on an oscope. I would think you are indeed getting distortion. Good luck - Arthur
drubin OP
3,285 posts
 
Thanks guys.

I use HT Pro Silway II 2M interconnects between the two.
unsound
7,367 posts
 
Could you give us the complete system?
shrinkmore's avatar
shrinkmore
2 posts
 
Interesting coincidence, "sounds" like my problem as well. I posted the thread just below this one. Any help on that thread would be greatly appreciated. Cal Audio Alpha DAC mismatch with Adcom GFP 750 Preamp.

Thanks,
Doug
drubin OP
3,285 posts
 
So...I asked Nelson Pass (duh!). He says that, yes, it is 11K single ended. He added that I could insert
resistance in series with the input if I like. The gain of the X150 is about 30 dB, so if I put 22K in series I would still get 20 dB gain.

What do people think of this idea?

By the way, the reduction in gain should not be a problem, at least on the face of it. The lowest setting of the First Sound is sometimes too loud as it is.
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