2. amps-preamps
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power amp/pre amp input and output impedence question

Hello, im in the process of researching a new system, low and behold my limited knowledge has led me to try understanding the input and output impedences to better assemble my new system as to the power amp and preamp.

in all of my years as a Hometheater guy I've avoided such topic because with "most" HT gear it all works together just fine.......

Hear I am many years later "catching up" on terms I should know, I was gonna just google and read, but most of the time well versed members can get to the meat better than random google replies

Thank you KG

kgveteran

Showing 2 responses by georgehifi

georgehifi's avatar
georgehifi
10,312 posts
 
"Same for poweramp to speaker."
????

Yes "damping factor", stretching this one a little, but the lowest impedance of the speakers curve can also have the 1:10 rule applied to it that the amp is 10 lower than it or even better.
So if the speaker is 2ohms in the bass the amps output impedance "should" be 0.2ohm or better lower at that frequency also.

Then in there’s the capacitor coupled components, these need to be looked at first to see if the cap is big enough to maintain the 1:10 rule, if not there could roll offs at the frequency extreme
georgehifi's avatar
georgehifi
10,312 posts
 
kgveteran

yogiboy The rule of thumb is the input impedance should be at least 10 times the output impedance!
What yogi said is correct, the ratio of 1:10 or more.

EG:
CD or dac output impedance = 100 ohms, preamp input impedance should be 1000ohms (1Kohm) or more.
Same for preamp to poweramp
Same for poweramp to speaker.

Cheers George
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