4-6V6 TW?

[fusionbear]

Anybody build a TW using 4-6v6's? The reason I ask is that when I put 2-6V6's in my current TW build, it gets mushy real quick, but at lower gain settings, they sound pretty good. I'm wondering if the current Tone slut trannies could handle two more 6V6's and would it be worth it?
BTW I love the EL34 sound too.

[Phil_S]

EL34 has a filament draw of 1.5A each and 6V6 draws only .45A each. Yes, you should be able to run six of them without overtaxing the filament supply. I'd guess plate supply would be adequate for four 6V6, but I didn't stop to calculate.

I think that begs the question. Did you rebias when you put the 6V6's in there? Bias voltage can have a big impact. I don't see this being a plug 'n' play switch.

[Firestorm]

I think that begs the question. Did you rebias when you put the 6V6's in there? Bias voltage can have a big impact. I don't see this being a plug 'n' play switch.

Hmmm. Ken Fischer always promoted the Express as being able to take EL34 or 6V6 WITHOUT rebiasing. I suspect you have to get the bias "right" to begin with.

[Richie]

I've built one using the toneslut PT.... works fine. Its more of a concorde at the moment.

[Phil_S]

Hmmm. Ken Fischer always promoted the Express as being able to take EL34 or 6V6 WITHOUT rebiasing. I suspect you have to get the bias "right" to begin with.

I suspect what that really means is that the range of bias voltage available is appropriate for both 6V6 and EL34. I think that is true.

[Firestorm]

Actually, what I suspect is that it was marketing hype. What Ken wrote was:

"The Trainwreck Express amp is unique in that it is capable of using either two 6V6 (typical of Fender Princetons, Deluxes, etc.) or EL-34 (generally associated with Marshall amps) output tubes. They can be switched without adjusting the amp. Because of this feature, a Trainwreck Express amp should not be biased by current. Instead, it is recommended that biasing be done by the Voltage Method.

The correct bias voltage for a Trainwreck Express is -30 volts on Pin 5 of the output tube, which may be adjusted by using the variable adjuster inside the chassis. Normally, this adjustment will never have to be made. A special process at Trainwreck manufacturing headquarters insures that there will be little need for bias adjustment for many years!"

"Special process" indeed! I haven't checked, but I'll bet that with -30 volts on the grids, both EL-34s and 6V6s (at least RCAs, anyway) fall into exactly the place Ken wanted them.

[fusionbear]

I set my TW to -33vdc on the grids according to the Francesca schematic. Would that be ok for 6V6"s

[jjman]

Was it recommended that the impedance be switched between the 2 tube types? Is that the origin of the 2 OPT primary sets on the toneslut trannies?

[Phil_S]

I set my TW to -33vdc on the grids according to the Francesca schematic. Would that be ok for 6V6"s

The answer is, "it depends". You've got to gather the required information to calculate static plate dissipation. My guess is that -33v could be rather cold for your particular tubes, but you have not furnished enough info to determine that.

[gearhead]

Was it recommended that the impedance be switched between the 2 tube types? Is that the origin of the 2 OPT primary sets on the toneslut trannies?

http://ampgarage.com/forum/viewtopic.php?t=315