| More volume out of a twin? Replaceing tubes would not increase
nor could it increase volume. If you haven't replaced your tubes for
years,you might hear some difference with new tubes. To increase volume
or output of your amp you would have to consider improving your power supply
capabilities this could be either costly and/or destructive.
I've always considered Twins of haveing a clean sound.(sometimes
too clean) If you want to try to get a warmer sound out of it you could
try three things. 1. Replace the 2nd 7025 in from the left of your diagram with
a 12ax7. This is your second channel(vibrato)preamp tube. The gain and tone
characteristics of the 12ax7 is less than the 7025. Not a significant difference
but some... 2. Replace your power tubes with Groove Tubes 6l6's,these are rated
in a S for Soft category or H for Hard category from 1 to 10. 10 being a clean
sound to 1 for a distorted sound. This is expensive as the Power tubes could
run you around $100 3. Replace your 6l6's with El 34's which would involve some
resistor changes in the power amp section of the twin. These are what use to
be stock in older Marshall's. And are found in new Marshalls today from what
I've heard. This is not a recommended job for anyone as there are potential high
voltages floating around in a tube amp after you power it down and let it sit.
This will increase your dynamic range and give you a warmer sound. Power
tube replacement is worth doing by yourself,but I'd have your bias checked if
you do. The above three suggestions are from the least cost to the most....
There other twin owners here who have had some experiance with some
of these suggestions.......
Rick
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First of all note 309 talks all about tubes.
I have a Fender twin reverb that I just finished retubing. Since
I hadn't retubed it in about 5 years I decided to change all 10
tubes. I ended up buying Groove tubes all around. I purchased my
twin new in 1979. I think my tube arrangment is the same as yours.
Anyways, a complete set of groove tubes for my twin cost about $150.oo
A quartet of 6L6GC's alone cost $80.oo. The 6 other tubes are $12.oo
each. I believe Mesa tubes will cost just as much, but Groove tubes
offer you a choice of ratings. I had planned to buy a rather soft
tube to get some distorsion out of it, but salesmen in 2 different
stores didn't recommend soft tubes in a twin since it is a push-
pull amp. I wanted it to sound at least a little bit warmer, so
I bought #4 hard power tubes. I do notice a warmer sound, and a
lot more clarity and sustain. I checked with a repairmen about
having the biasing checked. He said it is a good idea to check it,
but not always needed. He said that worse case, if the biasing is
off the power tubes would glow cherry red. I plan to have mine
checked out and have the pots cleaned anyways.
I priced a set of groove tubes at Mr C's in Marlboro, and they
wanted $175.oo for the complete set. It would have takin him a few
days to order them too. I hate to admit it but I ended up buying them
from Wurlitzers. They had them in stock and the price was right.
Good luck. Get ready to spend some money for good tubes.
Mark Jacques
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