New preamp, loss of low freq.?

Amps input imped is 10 kOhms

preamp: output 50 Ohm
input imped 47 KOhms

max output 10 volts

b&k output is I think 17 or 21. Pro 10 mc

onkyo p-308 not sure

Georgelofi;

Amp 10kohm, this could be the problem if your preamp is capacitor coupled on it’s output. As if the preamp’s output cap (if it has one), the size of it could have been calculated for a more normal (industry standard) >47kohm input impedance power amp.

Which the size of the cap may have been done so it’s say -3db at 10hz with a 47kohm poweramp. Which is fine.

But if that amp is 10kohm input then the -3db point will be 4.7 x higher at 47hz easily heard and so will sound like it has a bass roll off.

To test this, you can find out if the preamp is capacitor coupled by talking to the designer, or a quick test is to get another amp that you know is >47kohm input impedance and see if it still has a bass roll off.










So, I purchased a amp or preamp that is a mismatch? And won't sound good??  Wtf, I'm always fuc**ng something up. 
Tried for a stellar system, and always something wrong when I make a purchase,    Always!!!! Damn.

what is recommended? Sell preamp?

George,
Yes, the amp's input impedance is extremely low at 10kohm, and is not a good match for this preamp. But the preamp's output impedance is very low, so an amp with an input impedance lower than 47kohm can be used for testing, correct?

If he can borrow an amp with an input impedance of >25kohm approx., it should be adequate for testing. Your thoughts?

George,
From a design perspective, why does the McCormack have such a low input impedance?