In Reply to: Restoring a Traynor YBA-1A: EL34's @ 560Va 535Vg2 ?!?!?! posted by Jim Doyle on April 13, 2007 at 09:21:07:
Peter Traynor used a "trick" that allowed higher Vp and Vg2 voltages by tying the supressor grid to the raw negative bias supply. See if pin 1 ties to the bias supply - if not it's probably grounded or tied to the cathode (pin 8). Also he switched from Mullard EL34s to the USA/Canadian produced "big bottle" (like there ever was a "slim bottle") 6CA7 which is a much more robust tube than the EL34 (disassemble a few dead examples and note that the plate material is a couple of thousanths of an inch thicker and there is much more surface area).While I've seen some comment over the years that suggested that a negative supressor grid made for a "colder" sound I've not observed this personally. If the original 6CA7s work leave 'em in - the newer "issue" of these gets good reports but I still doubt that they are a rugged as the originals and 6550s definitely sound "cold/sterile" in these amps.
Rob
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Follow Ups
- Re: Restoring a Traynor YBA-1A: EL34's @ 560Va 535Vg2 ?!?!?! - Rob Mercure 15:01:57 04/13/07 (0)