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In the Forum: Audio Discussions
In the Thread: SET amplifiers

Post Subject: DSET is NOT a SET in context of this conversation.Posted by Romy the Cat on: 12/15/2014

rowuk wrote:
I have experimented with SS/SET and now DSEP for ceramic magnet horn drivers. I will agree that ceramic drivers with SETs that I have heard being suboptimal, but after a year of DSEP, at least for my use case, I am quite content. I cannot explain it in a technical fashion, but in spite of standard Mundorf caps and standard resistors - but a remappable OPT, I am VERY happy with the sonic result. I have had no trouble with integrating the "sheen" of the violin (especially during the initial attack or the decay), piano or soprano. I never got this result with ANY SS amplifier.

Your experience with DSET is kind of irrelevant to the conversation of SS vs. SET with ceramic. Put in this way it is relevant only because it in fact proves the SS/ceramic problem. You need to understand that in context of this question DSET is NOT SET. A definition of SET is a single ended amplifier, presumably in A1, having output triode and one single OPT that make amp properly loaded across the whole amp's band pass. The properly loading implies that LF, MF and HF produce the reference volume levels more or less consistent harmonic structure. It is easy to measure with some training it is easy to recognize by hearing.

DSET is a different animal. DSET discards the wide bandwidth by initial functional specification and assumes that the amp will produce the desired and targeted harmonic texture ONLY in very narrow frequency range, as the result a LOT of compromises and modifications are made in SET in order to accommodate this very specific DSET objectives. For instance let presume that you optimize DSET's OPT. With a "normal" set you have the output stage that let say loaded with 18x transformer. You have fine overall sound out of your Alnico wide range driver. Now you decided to do multichannel with DSET with the same types of the drivers. Your do your DSET and use the same 18x transformer, well perhaps you go with faster core, lower DCR, restricted LF and lower capacitance transformer and you would feel that to get the same harmonic texture fro the same driver you would slightly load your output stage, let say now you chose to have 16X transformer as your amp become "faster" and you feel that you need some harmonics to deal with your more transient overtones. Then you got a good ceramic driver to replace your alnico, let presume that they are the same only magnets are different (which is never the case but this is a part of a different conversation). Now you will feel that your DSET with 18x transformer is not too expressive and that you are losing the "bobblenees" in sound. Changing the transformer to let say X25-X28 would give you the formal speed at highest octave. You will still have compromised lover octave of your narrow band channel but you might play with upper band of your next lower frequency channel to deal with it. This is juts an illustration but this is VERY close to real life illustration.

Let see what happened in the illustration in reality. Moving from X18 transformer to X28 you effectively drops the amp output impudence, increasing the driver damping, increasing the amount of current your amps can send to the driver and deceasing the reactance of the amplifier to the driver's coil feedback. Ironically you are making you DSET to behave like it was a …. SS amp. That was my whole point. I certainly do not say SET or DSET can't drive ceramics. They might but I would not use ceramics for any more of less MF or HF anyhow. Still, if ceramics are used then SS like driving characteristics of amplifier are very desirable in my view.

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