power amp/pre amp input and output impedence question

"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

I notice as i research amps and preamps, sometimes these specs are hidden away or non existent in the owners manual  :0/
 
Why would they not include these important numbers ? Is this kinda like when a manufacturer says an amp can put our 1000watts/ch @1Khz and not a full bandwidth watts/ch, not just a convenient 1Khz signal which is fairly easy for the amp

@kgveteran Yup! Sometimes the output impedance of some preamps isn't all that low (particularly tube preamps) even though on the right setup it can sound pretty nice. In some cases the manufacturer might not have even measured it.

We don't specify out output impedances either, but we **do** spec that they can drive a 600 ohm load and that the output impedance is flat with respect to frequency.

Gotcha

Hello all,

When looking at my ARC component specs the ratio is well beyond 10:1

My Classic 120 mono block amp has an input impedance of 100,000 Ohms
My LS3B preamp has an output impedance of 500 Ohms

That ratio is 200:1

My next amp will be a REF 75, which has an input impedance of 300,000 Ohms.

That ratio matched with my LS3B will be 600:1

Am I doing my math wrong here?  This seems to be so well beyond the 10:1 target to not be of any concern.

Wondering about mixing brands, I checked a Conrad Johnson preamp.  Its output impedance was 100 Ohms that would drive that ratio even higher.

Next I went to McIntosh's website and the C2600 preamp doesn't list the output impedance.....only input at 44,000 Ohms, while my LS3B is 50,000 Ohms.

Are there some extreme examples of mixing brands where this is a concern, but most often not at all?