Fender 6G8/6G12 inspired build

[Esquirefreak]

So, long time no build...

I'm in the early phase of putting together a new amp, based on the 6G8 preamp and the 6G12 power amp. I'm reusing most of the parts from other builds and parts I have laying around.

Biggest difference is that I have swapped out the LFO CF triode for a mosfet. So 5 tubes instead of 6 (or 5½ really).

I'm gonna be using a Deluxe Reverb chassis and build a head cab for it. I know that there are nice replica brownface chassis on eBay, but shipping to Sweden is more expensive than the chassis itself.

I'll draw a schematic once I have proof of concept and I'm statisfied with the amp.

/Max

[Esquirefreak]

Main board drilled.

[Esquirefreak]

And populated.

[Esquirefreak]

Pots wired up

[Esquirefreak]

Cap board borrowed from the left-over-bin.

[Esquirefreak]

Heaters ✔️

[Esquirefreak]

Starting to look like an amp

[Esquirefreak]

Almost there

[Esquirefreak]

Done.

Fired right up without weird noises or mishaps. Dead quiet at idle and very loud when played.

Only changes I've made, so far, was to decrease the 10M R from the LFO output to 4M7. And then I increased the NFB R from 22k to 100k, which gave me a softer response.

This is my first build using a James TS, so I have yet to figure out if these TS component values are what I want.

I might experiment with the bias and plate load Rs in the first 2 gain stages. But for now I'm very pleased with how this came out. Gonna take a break from amps for a week or two before making the head cabinet.

/Max

[tubeswell]

This is my first build using a James TS, so I have yet to figure out if these TS component values are what I want.

Well done on getting it right first time!


Re the James TS, I've guilt a few amps with these and the attached schematic is what I find produces an ideal combination for me (when driven by a 12AX7 triode). With both pots at mid-rotation, the output is dead flat. With both pots cut, there is a mid-hump. With both pots at full rotation there is a mid-scoop. The slope switch enables a decent growl with P90s. The raw switch is completely unnecessary and optional. YMMV

[Esquirefreak]

Thanks!

I may temp in a TS outside the amp to try different values, atleast for the normal ch which I think has a little overwhelming mids. Will use your values as a starting point!

I think the vibrato ch sounds good, and the hi/lo filters is another variable that affects the sound. The taper of these tapped pots are weird, though. They feel a little binary, like on/off. Very narrow window between too little or too much treble.

/Max

[Esquirefreak]

Is the slope resistor replaced by the 70k tap here? I couldn't figure out why that resistor (which is part of all other James TS schematics I've seen) is missing.

[tubeswell]

Yes its a slightly different way of getting the result