Ron,
Please don't think I was taking you to task. I just "prefer" to put the tone stack last.
Too many are too happy the other way round.
I guess that's why there's more flavors than just vanilla ice cream.
Nice work by the way.
A lot of builders just solder the wire into the bottom of those hollow turrets, makes for
a very "clean" presentation.

Tom

Mike,
I don't see 2 100 ohm resistors in the layout coming off both sides of the filament supply to form the "biased reference point" described in the theory document. I use a positive bias supply in my amps to do just what they describe (I don't build any cathode biased amps, but taping the cathode works, with zero cost, what could be better?). Your layout document looks like they have you shorting pin 7 directly to pin 8 and that is not going to accomplish what is being described in the theory doc. I'm done for the night, but I'll take a closer look at the schematic in the morning. You either have to connect the 6 volt supply center tap to what they label "point A" (if the tranny has one) or created the "virtual" tap with 2 resistors, generally 100 ohm. The drawing they label Figure 29 is right, that layout is not.

You might ask some questions regarding that on their forum. My membership has lapsed.

Tom

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Mike,
No!
The drawing (fig 29, page 32) in the "Theory" doc is right.
The schematic and the BOM do not have the 100 ohm resistors, but it should be an easy fix.
As I stated above, this is not a deal killer, just not the "clever" fix described in the doc.
I reference the filaments to about 50vdc in all my amps, I just have two bias supplies, one negative for the power amp and one positive for the filaments.
I'm lazy so I'll ask, does the power tranny have a center tap?

Tom

Mike,
Here is the quick fix. Leo always used pins 1 and 6 as terminals for the screen and grid resistors, right? We can't use pin 1 as this is the secondary grid, but we only need a single terminal. So, jump pin 2 to 6 via a 100 ohm resistor, likewise jump pin 7 to 6 via a 100 ohm resistor and jump pin 8 to pin 6; done! You have your "clever" fix.

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Mike,
I PM'ed my cell if you have any questions.

Tom

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Mike,
This is an example of "cut and try". If it ain't broke...
I will say this, EVERY production amp I know of either center taps the filament supply, OR has the 100 ohm resistor pair to ground (the virtual tap). In Fenders its usually on the pilot light assembly.
I do know this. As I "lift" the filament string off of ground (I have a multi-turn pot on the + bias supply, much like the negative supply) the "hum" increases, then a some point (I have the exact voltage in notes somewhere) it begins to go away. Anymore I just set it at max, about 50 volts depending on the power supply.
Personally I would never have figured out that you could remove the virtual tap, if the tranny isn't center tapped I put the 2-100's on my bias supply board.

But again, IF it works...

I'm glad you found the explanation, now you can rest easy.

Yours in the quest...

Tom

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Way Cool!

Tom

Really cool pictures!
Have you considered DC heating?

Wilko

That's some fine lookin' work, Mike.