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An ignorant question about impedance

I've read over these many years about the importance of properly matching a preamplifier's output impedance with an amplifier's input impedance. I've always just accepted this as something that has got to be dealt with by folks who understand such things. But now I'm wondering: What happens when there is a mismatch? Is there some threat to the equipment, or does the reproduction of music suffer in some obviously discernable fashion? (Highs or lows or mids are like this or that or some such?) I recognize that this is a boneheaded query, but I've found myself wondering and I've not been able to find the answer through my online searches. If someone could point me in the right direction, my non-technical mind would rest easier. Thanks.
hodu

Showing 1 response by newbee

newbee
4,807 posts
 
Arthurs answer is correct, but FWIW although there are suggested guide lines for calculating the appropriate ratios (10 to 1, for example, i.e. a tube pre-amp with a 600 ohm output should be matched with a power amp with an output higher than 6000 ohms) it really depends on how the units were measured - not all spec's are equal. Interestingly I've run amps/preamps with less than a 10 to 1 ratio with no problem and some with a ratio much in excess of 10 to 1 with roll off. IOW, you've still go to listen to a combo to be sure you've got it right! Ditto with Athurs comments on speakers and tube amps. Listening to a combo is very important. If the speaker/amp impedence issues interest you (and I think they should because they are far mor important IMHO than amp/pre amp issues, especially to tube users, there was a recent thread with much excellent info on this.

Hope that helps a bit.
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