Biasing a 20th Anniversary Ecstasy (EL34)

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Hello! Think it's new tube time for my XTC. I haven't re-tubed this before. Any guides on biasing it? There's various ways to bias a 100W EL34 amp, any particualr one recommended for these? Is it set a voltage on a test-point job? Or some kind of in-line current thing? Or do people use somethng like a bias-rite or have some other method? And what voltage/current is the recommended?

I'm used to setting a voltage on a documented test point for my other non-Bogners, so I don't know what the "normal" way to do these is.

Also any accepted wisdom on which are the best brands for pre and power tubes for these? (At sensible price points, rather than fill it full of NOS Mullards!)

I presume I need a matched quad too (doesn't bias in 2 pairs)?

Thanks! :)
 
(FYI this thing seems to be whistling far too easily on Ch3, so although there's quite a lot of gain here, I think something has gone microphonic to whistle this easily)
 
Me said:
(FYI this thing seems to be whistling far too easily on Ch3, so although there's quite a lot of gain here, I think something has gone microphonic to whistle this easily)
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Could be a bad preamp tube? Do you have a know good one you can swap in to each position to see if the noise goes away?
 
@M@ttC3: Yeah, that's what I'm hoping as I have various ECC83s floating about and it's a nice cheap(-ish) fix.

This thing hasn't had new tubes since I got it 2nd hand though, so if I find it's those I have a brand new set to stick in, if I know how to bias it. Diezel have a nice easy tech doc and bias instructions / test points printed on the PCB. Hence I wondered if there's an equivalent Bogner doc or something.
 
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