What's the greatest bargain in SET these days?

01-06-15: Charles1dad
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.

Good question, Charles. I don't know the answer, of course, but if I were to hazard a guess, and assuming that the 10.2 ohm figure is correct, I would say that the need to minimize the size and cost of the output transformers probably has something to do with it.

Best regards,
-- Al

It's always about the amp/speaker synergy...always. That is why, for example, the Inspire amp may not sound as good on a particular set of speakers. All about the synergy. Dennis uses good trannys on his Inspire amps as an FYI.

I love this thread as I read the whole thing last night! My speakers are 90db efficient and 8 ohm. They to not dip below 6 ohms and are pretty easy to drive. I have tried several 7 - 12 watt SET amps and find I get enough volume....with the right music. The type of music played is a factor we need to add to the amp/speaker synergy equation.

If one listens to jazz, small ensembles etc, then I found 8 watts was plenty with my moderately efficient speakers. This type of music is not as demanding on a system. Now play some music that is dynamically challenging, then the lack of watts and lack of headroom is readily apparent.

So in addition to the room size and prefered volume level, one needs to take into account what type of music is played most of the time.

Rebbi, I think you made a wonderful choice with your AN kit and view your blog almost daily. Someday I will build a nice SET amp and actually looked at yours pretty seriously. I wish AN offered the same essential amp with no electrolytics and no circuit boards as a kit. It would most likely require a larger chassis to fit the ASC or GE oil caps etc...

Are any of you aware of a SET kit that uses all point to point wiring and no electrolytic caps? I would also like to try transformer coupling or direct coupling in this SET amp.Not sure such a beast exists in KIT form?

Interesting spec on the Coincident EL34 amp. I think Al is spot on with his answer as to why. It is cost related and gives the builder an opportunity to make the best quality output tranny within a smaller range of ideal operation.

A typical SET amp has an output impedance of some 3 ohms (no feedback) with many under that. Speaker matching is especially critical with this amp. I think Dick O. got it right in his review warning folks to be careful and clearly showing the sonic results of mating this amp with a "typical" speaker. Not sure it is his responsibilty to hunt for a particular speaker for the review? Maybe it is?

Hi Al,
Yes the output transformer is a logical culprit. Except in this case two things counter that assumption to some degree.
1) Israel places much emphasis on the importance of transformer quality and is consistent in that stance.

2)6 Moons and Enjoy The Music reviewers as well as Mikirob and Brownsfan attest to the very high quality sound from the Dynamo. These different users cover a variety of speakers as well.

These factors would suggest that the output transformers must be pretty darn good at a minimum. I suppose it's possible to have good quality transformers that suffer unusually high output impedance.

I believe it is Dick Olsher's responsibility to utilize different speakers that have a chance to mate well with a given amplifier. Most reviewers would not mate a low-watt SET with grossly incompatible speakers except to note, for example, that one must be careful in speaker matching. Then he, the reviewer, would generally base the review on compatible rigs to let us, the reader compare and contrast.