2. amps-preamps
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impedance matching amp/preamp

My amp is late 80's McIntosh 2250 solid state. My pre amp is a modified Ming Da... Impedance is way off, even though I think it has a very good sound. Amp input 50K the preamp outputs 100k which is totally backwards from all I read on the net. I have also used an AudioResearch preamp that was close in ohms, and my Onkyo AV receiver that also matches up with the amp. Neither sound as good as the Ming Da. My queston is how important is impedance matching and what am I missing.?
keslerd
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almarg's avatar
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almarg
9,670 posts
 
You are not missing anything. The spec is wrong:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1268272109

Enjoy!

-- Al
keslerd OP
20 posts
 
The spec sheet says Output Impedance 100K, Response Audio, the company that modified the unit, says Output Impedance 100K.. I do enjoy this preamp... but because the numbers are so far off... just had to ask... Thanks I will try to be happy.
mapman's avatar
mapman
22,198 posts
 
I think I came across something like this before where 100K output impedance is the recommended input impedance for the amp to match the pre-amp's output. Not saying that is the case for certain in your case, but it is possible. 60K input impedance on the SS amp should match pretty well in general to most tube pre-amps I would say.
mechans
3,048 posts
 
Would some one kindly explain why an impedance for input to an amp should be so high. I think of as the resistance to the voltage from the preamp making it extremely hard to drive the amp. If the preamp has a output impedance of 20 times that would that mean that the signal leaving the preamp has to be strong enough to to to overcome that impedament as well. Anyway I am clueless.
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