Cash in hand

[Andy Le Blanc]

So the order is for a 58 bassman 5f6a.

With some variations, the clients tube favorite is KT66, and the front end
of a twin 5e8a. 4/10 custom cab.

I was thinking about maybe putting the presence control on a push/pull,
to switch between a 5f6 and a 5f6a.

great fun to have a build with a client... should be fun

[Cliff Schecht]

The 5ExA amps that share the same lineage (Twin, Pro and Bandmaster IIRC) are such great sounding amps. Love that circuit, especially with the dual 5U4 configuration. Have you considered making this an option? Makes a very noticeable difference in feel and sound (like what most tight/loose switches should do).

[Andy Le Blanc]

I share the same love for that era fender amp, the front end variation are great fun to explore.

I like the dual rectifier two, I'll run it by the client.

looking forward to this one, I'll most likely bias it to 1/2 the PT current rating.

so 200ma. PT, and a pair of kt66 @ about 100ma. for the pair, pretty close to the Genalex data.

Most of the data for kt66 put the screens well below the plate, should be fun build.

[Cliff Schecht]

I like the sound of aggressively dropped screen voltages. Makes the pentodes act more like pentodes and brightens up the overall response of the amp. You should gain a little in output power too because the pentodes will be operating more efficiently. Sounds like a really fun build, please keep us up to date!!

[stephenl]

I like KT66's with 390v plates, 275v screens, 8k primary, and cathode bias with 250ohm unbypassed

[Smokebreak]

I've been very interested in this era of tweeds,as well, and have just begun researching. Which of these would you guys say gets the dirtiest? I may even be looking at some of the cathode biased ones.
Looking forward to your build, Andy!

[Cliff Schecht]

5C3/5D3 Deluxe with 6SL7's is a raunchy little fucker. Cool circuit too but very picky about layout.

[Blackburn]

I built my 5C3 stock with 6SC7s. PTP. It can get pretty raunchy, but I don't prefer that at all from that amp. It's pretty dark (Normal Input) and great for jazz.

[matt h]

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[Blackburn]

The 5C3 uses a paraphase PI. I run it pretty low on the volume dial and don't mind the very subtle breakup at that point, but I mostly like its dark tone for cleans.

[matt h]

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[Blackburn]

Nope. It's grid leak biased for both of V1's channels. The only amp I've done that sports that. Can't say I prefer it, but it's an interesting departure from the norm.

[matt h]

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[Blackburn]

They don't look different at all to me, but I just pulled up '5B3 Schematic' on Google. Maybe there's another version?

I'm only running 'buckers through that amp. Like I said, I don't dig that amp tearing it up, just slightly overdriving and mostly clean, which doesn't involve changing the volume on the amp or guitar. I have played the amp wide open, and I'm sure there are some who'd love that, but it's just not for me. YMMV.

[Andy Le Blanc]

I've built rigs with a wide variety paraphase and cathodyne invertors.
The simplest circuits have the most tone color... even order harmonic distortion.
they can be nasty good... or if you mind text book conditions, and balance the plate voltages carefully, AC/DC balance, they can actually be fat and clean before break up.

This build is long tailed cathode coupled, really very common circuit, the only detraction is natural reduction of even order harmonics.

I actually prefer a paraphase, the color on a 50w power side is a blast to play through.

Today I got the sheet metal to fab the chassis, 12x24 flat... doweling to glue and peg the cab, router bit for jasper circle cutter jig thingy.

It'll be fun to see where screens voltage land in the build, I been liking
setting up the power side at max dissipation with the screens 5-10v negative relative to the plate at zero signal... at least with 6l6

the data for kt66 suggest screens much lower, should be fun