Impedance mismatch question

Thanks, Georgelofi. As I said earlier, not meeting the 10x guideline (properly defined as described in my post) does not necessarily mean that there will be a problem. But meeting that guideline assures that there won't be a problem.

And as I'm sure you realize, the specific value of the coupling capacitor (which affects the amount of variation of output impedance as a function of frequency), and the deep bass extension of the speakers, and the deep bass content of the source material, are all relevant variables. So I would suggest caution to anyone who might be tempted to apply the results of your experiments in a universal manner.

For preamps that have been reviewed by Stereophile, the measurements and associated comments that John Atkinson usually provides in conjunction with the reviews are a valuable resource in assessing this issue.

Regards,
-- Al

Hi Al,
Regarding tube preamps would an output trandformer in place of the capacitor eliminate or reduce this potential fluctuating impedance mismatch ?
Charles,

Hi Charles,

Yes. In general I'd expect output impedance variation as a function of frequency to be much smaller in the case of a tube preamp having a transformer coupled output than in the case of a tube preamp having a capacitor coupled output. Assuming reasonably good design of the transformer and the output stage, of course.

Best regards,
-- Al

Thank you Al.

Thank you all very much. To further clarify why I am asking I will list my equipment;
Audible illusions 2d pre
Cary 308 cdp
Emotiva xpa 2 gen2 amp
Gallo reference 3.5 speakers with gallo sub amp
Power cords are tributaries silver and grace note custom
Interconnects are homegrown audio super silver bw all components
I am waiting on a set of aes six pac tube amps to arrive as well.

I ask about the impedance mismatch bc I was recommended to have at least 50k ohm input impedance on the amplifier side. Sometime next year I am looking to purchase an emotive sira or custom emotive amp and Fred volts too says that impedance matching for a 23k ohm amp is difficult.

I have a slightly bright and forward sound right now that I am hoping to cure with the six pacs. But, I really like the dynamics of the emotiva amp. I picked it up as a fluke and am actually really enjoying it. It sounds very krell like to me. That being said, I never bought krell gear because while they have always sounded good, I always found them bright.

I have been wondering of late if the impedance mismatch could have been causing some of the brightness I have been hearing. It wasn't there with my old b&k ex442. But, based on the comments above it sounds as if the bottom end is where I would be hearing anomalies.