High impedance Speakers

You can DIY try PHY open baffles.I have built a quite a few PHY systems, km30 is very good, but as you say a bit costly.Sometimes I custom build PHY systems they do have a 8in that costs a bit less.

Atma Ralph sez:

Also noticable is the increase in transparency (read: DECREASE in distortion)

Likewise with more sensitive spkrs vs less sensitive.
Have you noticed this & is there a reason-- or is it just my impression? Cheers

A speaker that is easy to drive (more efficient) requires less of the amplifier but also of *the preamp* as the volume does not run as high. As long as hysteresis loss does not play a role (as in a large transformer coupled tube amp) the distortion will be lower- again improving transparency.

The lesson is that if you are investing in a tube amplifier, the investment is best served by a speaker that is 8 ohms or more and high efficiency. In the old days 16 ohms was common and there were even 32 ohm speakers. Since the advent of transistors, 4 ohms has replaced 16 ohms for being 'common' but to the detriment of tubes.

Using the 4 ohm tap on a higher impedance speaker will yield more 'current' but neither the transformer nor the tubes will be properly loaded. The transformer can ring (adding distortion) so it should be loaded properly. If the 4 ohm tap is used on a 16 ohm speaker, a set of tubes with a 3K load on them will suddenly see 6K. They will not make as much power and there may be other anomalies as well.