I recently built a Matchless Clubman preamp (driving a 12AU7 power section) with a 6SH7 pentode as per schematic. I read on Harmony Central reviews that Matchless has used EF86 in their later Clubmans, with some differences in tone.
I have a good source for the 6SH7, and I've heard that the current production EF86's are not particularly good. So now I'm wondering how good of a replacement would the 6SH7 make for EF86 in guitar amps in general? Does anyone have any comments on the tonal differences? What about electrical compatability, how should circuits be changed to accommodate the 6SH7?
Preamp pentodes
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Preamp pentodes
Last edited by Mr.Curwen on Mon Mar 22, 2010 10:59 pm, edited 1 time in total.
Re: Preamp pentodes
The 6SH7 has somewhat higher gm, but the main difference is that the 6SH7 has way more screen current (screen current is about one fifth anode current in the EF86, but it's more like double that in the 6SH7!) so for similar operating conditions to the EF86, you are likely to need a smaller anode and screen resistors with the 6SH7.
Overall the characteristic curves look very similar to the EF86, so tonally I would expect them to be not a million miles away from one another, assuming they are set up similarly.
Overall the characteristic curves look very similar to the EF86, so tonally I would expect them to be not a million miles away from one another, assuming they are set up similarly.