Which high power SET

06-24-14: Edoit
To rephrase my question, which of the 3 on the list would be the best match for shindo masseto pre amp?

My suggestion is that a more important consideration is which of the three amps is the best match for the speakers. As you can see in the impedance plots for the SHL5 shown here, its impedance is in the vicinity of 6 ohms in the mid-bass and upper treble regions but rises to a peak of about 34 ohms at a little under 2 kHz, which of course is a particularly important part of the spectrum. The interaction of that impedance variation with the relatively high and also model-dependent output impedance of a SET will cause significant tonal balance variation as a function of which amplifier is used.

It follows from that, also, that a given SET amplifier will likely sound significantly different when used with your particular speakers than when used with many or most other speakers.

One more reason, in addition to those that have been mentioned, to try to audition in your system prior to purchase, and for why a SET might not be the best choice for use with your speakers.

Regards,
-- Al

Edoit, I second all of Larry's comments, including his emphasis on the word "may," except that I would add "widely varying speaker impedance" to his mention of low speaker impedance.

The fact that the speaker's impedance varies widely, from about 6 ohms at mid-bass and upper treble frequencies to as high as 34 ohms just below 2 kHz, will cause the frequency response of the amp/speaker combination to be highly sensitive to the output impedance of the amplifier that is used. Since SETs tend to have particularly high output impedances relative to most other topologies, and also because output impedances tend to differ significantly among different SET designs, the acceptability of the resulting sonics pretty much comes down to a matter of chance.

An ideal speaker candidate for use with SETs would have high efficiency, high impedance, and relatively little variation of impedance as a function of frequency. Which is not to say that results will always be unacceptable if those criteria are not met, but you would be taking a big chance if you were to buy (without return privileges) before trying the amp in your system.

If you do try out a SET in your system, given the impedance curve of your speakers what you should particularly look out for with respect to potential frequency response issues would be an over-emphasis of frequencies in the 1 to 3 kHz area. And, correspondingly, an under-emphasis of the mid-bass and upper treble.

Regards,
-- Al

Ait, congratulations on what is certainly one of the most spectacular DIY amplifiers ever!

As a point of information that may be relevant to the thread, do you know what its output impedance is, or alternatively, its damping factor?

Also, what load impedance is its output tap optimized for?

Regards,
-- Al

Ait, thanks for the detailed response. Wrm's choice of the word "awesome" is an understatement, if anything :-)

I'll add to your comments, relevant to the thread, that the 1.2 ohm output impedance is of course significantly lower than that of more typical SETs. And it is low enough so that the effects on frequency response resulting from the interaction of that output impedance with widely varying speaker impedance are not likely to produce unintended results when used with speakers designed with the expectation they would be used with either push-pull tube amps using feedback or even solid state amps.

And thanks for the invite. I'm not in NJ, but every once in a while I have occasion to visit northern NJ, and I'll keep your invitation in mind.

Best regards,
-- Al