1967 Bassman build

[mikepukmel]

Which tube socket is it that shows this issue? The one closer to the PT or or the one farther away?

[Enzo]

Socket #1 on left, count them down the row of sockets.

[mikepukmel]

Great post and question Randall. Im very curious about this kind of thing as well. I have a frankenstein build, where the main eyelet board dimensions are no where close to the original fender version for the given AB763 circuit. The original board, best as I can tell, is a lot wider and somewhat less deep (front to back of chassis). I could mount the board so that V1 and V2 are closer to their respective board components, or move the board towards the power trans so that the components on that side of the board are closer to the phase inverter and power tubes. Having zero experience with this stuff, curious as to what effect either 1) longer wiring to the power tubes, or 2) shorter to power tubes and longer wiring to preamp tubes, has on things like bad oscillation. Q: Do your 6L6's work ok in any other amp?

[catalin gramada]

Twist tight the wires from PI output to power grids. Run all signal wires sticked to chassis ( even with some glue points). NFB wiring is a pain in the ass. Better to use a stereo shielded cable here but tight twisted wires works also good. Use a isolate output jack and run twisted wires from this jack directly over NFB resistors.

[mikepukmel]

Hi Catalin, Re the PI output, is the twisting of the pair more important than the length of the wire? Or a balance between the two?

[catalin gramada]

Hi.Yes it is. Keep the wires tight twisted and you can put into a thermocontractible tube to be sure will remain as so or tie it with cable tie. The only untwisted part will be the wires ends which run to the pins

I remembered saw sort of shielding method twisting a wire tied to chassis over those allready twisted wires. Think I saw in Fenders but not remember was a Fender rule or not. If you want to do so you can tie this wire at whatever DC potential you want, not necessary to the ground, but keep the other end isolated for safe reason

[Randall]

Sorry for the late reply, hurricane and all. I would center the board so as to reduce the lengths to both side. I'm not sure making one side shorter and one side longer makes as much difference as keeping plate wires away from grid and cathode wires as much as you can, and always crossing at right angles when you can't.

Haven't checked the old 6L6s in anything else

[bob p]

I hope you did OK with the weather.

[mikepukmel]

Sorry for the late reply, hurricane and all. I would center the board so as to reduce the lengths to both side. I'm not sure making one side shorter and one side longer makes as much difference as keeping plate wires away from grid and cathode wires as much as you can, and always crossing at right angles when you can't.

Haven't checked the old 6L6s in anything else

Thanks Randall, and, as Bob asked: hope all's well after the big storm.

[Randall]

Very little damage to home, but the evacuation and return was hell.

[Randall]

Well chassis is complete, built in the Tweed channel, and had a good player take it for a spin. This amp sounds great! Very authentic rock tones, articulate, but with hair. And that is only on 4. Very happy with it, now I just have to figure out if it is going to be a head or a combo. Flirting with the idea of a ceramic 75w combo.

[Justin Thomas]

Here's a vote for a single 12" or 15" combo. Maybe a 2x10". I sure wish my Bassman was a combo... instead, I lug around a matching 2x15 to go with it...

Justin

[Randall]

A 2 x 15"????

[bob p]

A 2 x 15"????

you haven't lived until you've lost the grip on one of these and watched it bounce down a flight of stairs.



mine went down a flight of concrete stairs, bouncing into the air off of each step and tumbling end over end. it was like watching a train wreck in slow motion. when it finally came to rest there were some scratches on the aluminum corners and trim strips but no other external damage.

I use mine for dual purpose. It's loaded with a pair of EVM-15L. Of course it's a good bass cab, but it makes an incredibly good sounding guitar cab as well.

[Leo_Gnardo]

A 2 x 15"????

Yes, Justin's gotta have it for that manly-man sound. Nothing twee about a 2x15, it's serious chunkin' tone.

bob p, IIRC that cab bit a chunk out of one of the concrete steps on its way down, right? Luv those Mesa cabs, I have the 1x15 version as a test cab in my living room. No metal edging, and I swapped out the clangy steel grill for black cloth long ago. Highly recommended! Works great too with a JBL 2220 or K140.