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previous: AC Heresy, I know ... but... <... -- 10/7/1999 9:08 PM

Re: 6L6s in a Marshall?

10/7/1999 9:50 PM
SpeedRacer	Re: 6L6s in a Marshall? The short answer is "yes", but there are conditions that must be met: 1. Your plate voltages must be within the limts of the 6L6, under the abs max of 500V for 6L6GC's, and preferably 460V or below for decent tone. (I think you have GC's, they didn't make GT's in the 6L6) 2. Your bias supply may need to be modded to give more neg volts since you'll likely need bias voltages in the 45-55V range where the EL34's are in the 30-40V range (ROUGHLY). Worst case you may need to make a voltage doubler (the Hiwatt mod in TTAB.. simple to do). 3. The Marshall's output tranny is close enough to the Fender's (3.4K Marshall, 4.1K Fender) although the lower imp will increase current draw on peaks so be careful not to bias on the "hot" end of things if you can help it. If you're B+ is in the low 400's this ought to work great IMHO. Also worth a try mis-matching the secondary 2:1 to bump up the reflected imp on the tubes (eg use 16-ohm cab on the 8-ohm tap) This will get you to 6.8K pri imp which is darn close to the 6.6k the JTM45 used.

10/7/1999 9:50 PM

SpeedRacer

Re: 6L6s in a Marshall?

The short answer is "yes", but there are conditions that must be met:
1. Your plate voltages must be within the limts of the 6L6, under the abs max of 500V for 6L6GC's, and preferably 460V or below for decent tone. (I think you have GC's, they didn't make GT's in the 6L6)
2. Your bias supply may need to be modded to give more neg volts since you'll likely need bias voltages in the 45-55V range where the EL34's are in the 30-40V range (ROUGHLY). Worst case you may need to make a voltage doubler (the Hiwatt mod in TTAB.. simple to do).
3. The Marshall's output tranny is close enough to the Fender's (3.4K Marshall, 4.1K Fender) although the lower imp will increase current draw on peaks so be careful not to bias on the "hot" end of things if you can help it.

If you're B+ is in the low 400's this ought to work great IMHO. Also worth a try mis-matching the secondary 2:1 to bump up the reflected imp on the tubes (eg use 16-ohm cab on the 8-ohm tap) This will get you to 6.8K pri imp which is darn close to the 6.6k the JTM45 used.