Impressed with Tubes

"Keep in mind that if you are investing in tube power, your investment dollar will be better served by a speaker that is 8 ohms or more (particularly in the woofer region) than a speaker that is 4 ohms."

Hi Atmasphere,
I've always understood this to be true of OTLs but how significant is the high impedance issue with push-pull or SET amps. This has always been a little confusing to me because it seems that while almost all speakers are classified as either 4 or 8 ohm, impedance charts can show quite a bit of fluctuation. I would like to try an OTL with my 8 ohm Mini Utopias but I believe they dip to 4 ohm and I don't know where.

Regards

I do have a tube amp (CAT JL2)that can handle low impedances, but it is expesnive and requires large transformers (the amp weighs 180 lbs!)and Atmasphere obviously uses a different approach. But nevertheless a higher impedance is always better for tubes and a smooth, linear impedance curve is important. I would think even a 4ohm nominal impedance would be ok, as long as the impedance curve was smooth, without large peaks and valleys at various frequencies - I think they call it impedance phase(?) or something. A discussion with your amp and speaker mfg always helps. I never understood much about the subject till Bobby at Merlin (speakers) explained some of this stuff to me and Atmaspheres contribution on the subject have always helped. The speaker in question seems to offer challenges to tube amps, even if they worked, they would "work" the tubes hard.

Pubul57 - I would have no problem agreeeing with your comments about PP/SET amps interaction with speakers with a flat(ish) impedence curve, and there is no reason that a quality amp can't handle moderate speaker impedence dips, BUT one of the problems is that amps have varible output impedence to deal with that can be as problematic as speaker impedence (one of mine has a rise to 3.5ohms in the mid bass) so its important, at least on paper, to match the amps varying output impedence with the speakers varying impedence. Not a walk in the park if your looking for anything approaching ideal matching of amps and speakers without listening. FWIW.

I agree with you, and when you do hear an good match between pre/amp/speaker it suddenly becomes obvious that something good is happening, a sense of balance from highs to lows. One advantage to well designed integrateds.

OK, you guys are making me feel pretty inferior here. Are you telling me that I should be able to listen to a specific speaker/amp combo and then determine that somewhere around say 180hz there is an impedance mismatch of 2ohms. Please don't tell me you're telling me that,LOL.

Regards,