El34, 6550 pin schemes, are they the same?

Guest · Post by **Guest** » Sun Jul 24, 2005 8:20 pm

I've got a superlead that was outfitted with 6550 tubes. I want to switch it to el34s. Are the pin schemes for the two types of tubes the same. Does anybody have a link to a website that has detailed information on pin identity for different vacuum tubes? Thanks.

rjgtr · Post by **rjgtr** » Sun Jul 24, 2005 8:32 pm

EL34s require one more pin than a 6550 or 6L6, fortunately Marshalls are all wired to be compatible with EL34s. The only change that is needed is a change to the Bias circuit. I'm sure there's a post here on how to do this.

Flames1950 · Post by **Flames1950** » Mon Jul 25, 2005 12:15 pm

Usually you end up adding a resistor in parallel to the current bias resistor. The bias resistor is inline with the bias adjustment pot, start by adding a resistor of the same value over the top of the original to halve that resistance value, and see if it ends up with about the right range.

jerryd · Post by **jerryd** » Mon Aug 01, 2005 5:19 pm

voodoo tech head section has an easy to read one