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In the Forum: Audio Discussions
In the Thread: Passive transformer based preamp
Post Subject: Re: Further problems with interstage transformers.Posted by cv on: 10/31/2005
T,
Agreed on the mumetal - it's wonderful stuff for transformers, just wish you could get it in the required core size for big outputs (well, maybe the US DoD can). Heavens know why AC spend a fortune on silver on an iron core.
RE: the Slagle autoformers and their lower than S&B inductance, that's a deliberate design choice on his part. Inductance ranges from 20H to almost 200H for the standard version, from what I recall, depending on how they are gapped.
Dave has been known to recommend bigger air gaps for more linearity of the perm and likes low driving impedances. Having heard his setup and 2A3 OPTs, I'm inclined to agree - the latter were particularly impressive, having a - dunno how to describe it - "inner calm" to the presentation.
Having said that, I appreciate the "impedance"/size-of-market tradeoff you made with the S&B design. Really must wire mine up sometime :-)
cheers
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