What's the greatest bargain in SET these days?

The 10.2 ohm source impedance is the thing to REALLY pay attention to when matching this amp to the appropriate speakers as Charles notes. That is a VERY high source impedance and would seriously limit the speakers it might be used with optimally. I can certainly imagine some compromises in performance when used with the wrong speaker. It seems designed with Coincident speakers in mind with their very high output impedance. I also totally agree with Charles that the quality of tubes used can make a HUGE difference in performance beyond the critical amp/speaker interface. One can't expect the best tubes in a 1.2K integrated amplifier. I would expect this amp could sound exceptional with the right speaker and some tube rolling. Dick Olsher is very technically oriented but could have been a bit more through in the why of what he heard. I agree that using a DIY speaker is not useful to most folks reading the review. He should have requested a pair of Coincident speakers or had on hand a speaker with a high enough output impedance to offer a fairer idea of what is possible with the Dynamo. What the reader is left with after the review is more questions than answers, at least I was. Dick has been at this long enough, he should have known better going into the review.

Maybe Al might chime in here with more technical insight.

Rebbi, thanks for calling attention to the Dynamo review. I haven't received my copy of that issue yet, but I'm particularly struck by the mention of the amp's high output impedance. A 10.2 ohm output impedance/source impedance on the 8 ohm tap will cause the resulting sonics to vary DRAMATICALLY as a function of the impedance vs. frequency characteristics of the particular speaker that is being used. The most neutral behavior being likely to occur with speakers having impedances that are both relatively flat as a function of frequency and relatively high. That is true of most SETs, but to a considerably greater degree than usual in this case due to the uncommonly high output impedance.

The 4 ohm tap will have a lower output impedance, most likely around half of that value, or 5.1 ohms, which is still quite high.

I assume, btw, that since those numbers aren't specified at the Coincident website that they were told to him by Mr. Blume, as TAS (in contrast to Stereophile) doesn't usually perform such measurements.

On another note, like the others I am very much enjoying following your extremely well done blog.

Best regards,
-- Al

P.S: My post just above went up within a few seconds of the one just above it by Tubegroover, and was composed and submitted before seeing his. Great minds think alike!

Best regards,
-- Al

10.2 ohm output caught my eye as well. That would make for some varied and possibly interesting results. Hard to see how that would perform well with most speakers, but again optimal performance and what one considers to be good sound are often not the same.

I wonder what accounts for such a high output impedance of the Dynamo. The Frankenstein has an output impedance of 1.8 ohms, quite a difference. Tim Smith found good speaker matches in his review despite this seemingly obvious limitation of the Dynamo.