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Single Ended Triodes (SETs), the ultimate tube lovers dream.

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Re: I'm with you on that

Njjohn,

The 08s is a very well designed amp. A good friend of mine has the AC heated version, another one the dc heated, yet another runs it with 2a3. I have heard only the ac heated ones, but I'm told the dc heated is even "better".
when you look at the schematics and parts selection, it has quite a few details to it that surprise, and shock the DIY-er. Every part is very carefully selected, the crucial items done in the house. The transformers seem to be of extremely well designed. The mains transformer is a C-core iron, _with_ air gap. That can be one factor why this amp strikes people with its direct, unveiled sound. I was shocked that a pentode driver could sound that good. My mentor told me that that should not come as a surprise, the old designs used pentodes to drive triodes, and it works extremely well. Pentodes have greater voltage amplification, that gives them potential for better dynamics. However, depending on how you set up the operating conditions, the very same pentode can sound excellent or crap. I beleive Yamamoto san has spent quite a few years figuring it out for the 717a, and he did an excellent job.

We might never know what has potential for excellent sonics. Decided to build a tiny amp for my brother, to start him on his audio journey. Triode (6j4/8532) driven pentode (6005, spec version of 6aq5). The pentode is in triode mode, the screen is fixed below the plate with zeners. Main design criteria was to build something small and relatively light (I'll have to ship it around the world).
Well, I expected OKish sonics, but got a smack in the face, as it sounds much better than it should.


Janos





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