Double Hot Cake

[Plexi]

I've built both versions: the '77 and the '03.
I want to put both in the same enclosure, like the double HC.


What's the deal with the middle-white knob?
As it says in the product description:

"The Double Hotcake has two Hotcakes: 'A' and 'B' in one box. The A is a Bluesberry version, and the B a normal version (the "Bluesberry" voicing of the Hotcake has a slightly less buzzy edge at the onset of distortion, and often works well when guitarists have amplifiers with extra extreme treble boost, like some Marshalls for instance). Both have three knobs and a footswitch as with regular Hotcakes. If both Hotcakes are switched on together, the A Hotcake drives the B, and its controls are bypassed, but an extra Drive control is switched in to adjust the its gain. There is also an extra clipping stage and a reduction in low frequencies to make for a better lead sound in the high gain situation. The A Hotcake has the usual buffered bypass (the circuit becomes a buffer in bypass mode), while the B Hotcake is hard bypassed using gold plated contacts."

What could be the trick here?

I'll left the 77's first and the '03 (presence knob) at the end: it will be better to mix.

[swever]

Probably a gain control between two stages? My guess is that it's only on when both hotcakes are on.

[swever]

Actually I realised there a volume control in both stages so my previous comment does not make sence. My new guess is that it feeds some of the input from the first stage into the second one (in parallel).

[Plexi]

Sure... here is the main doubt:
"If both Hotcakes are switched on together, the A Hotcake drives the B, and its controls are bypassed, but an extra Drive control is switched in to adjust the its gain. There is also an extra clipping stage and a reduction in low frequencies to make for a better lead sound in the high gain situation. The A Hotcake has the usual buffered bypass (the circuit becomes a buffer in bypass mode), while the B Hotcake is hard bypassed using gold plated contacts."

And what about the "extra clipping stage and a reduction in low frequencies"?

[GGBB]

The way I read it is that when A and B are both on, A's controls are switched out, and the white gain becomes A's gain control (or possibly volume) which "drives" B. They also change something to filter out some bass and add some clippers somewhere - how they do that is a mystery. I'm guessing they use electronic switching plus logic of some sort to do all that, but A is buffered-bypass, so it may use boss-style switching which could potentially also do all the other stuff. There's sure to be some kind of logic going on even if just FETs.

[Plexi]

The way I read it is that when A and B are both on, A's controls are switched out, and the white gain becomes A's gain control (or possibly volume) which "drives" B. They also change something to filter out some bass and add some clippers somewhere - how they do that is a mystery. I'm guessing they use electronic switching plus logic of some sort to do all that, but A is buffered-bypass, so it may use boss-style switching which could potentially also do all the other stuff. There's sure to be some kind of logic going on even if just FETs.

I assumed that the A side uses the old '77 switch (that acts as a buffer when its off)..as it describe.
Could be complex how it act only when the B channel its on: add clipping, bypass volume and presence knobs, change between Drive knobs, and change the EQ (presence).

http://2.bp.blogspot.com/-EL7kmAlHg_I/TxxcD4UF9QI/AAAAAAAAAqY/8j69jpNEfBo/s1600/Crowther_Hotcake-1977.gif

I'll leave the '77 with the traditional switching and presence switch in the A side, the '03 with presesence knob at the B side. I'll try the Bluesberry diodes mod too.
I don't knob about the extra clipping: I'll test the traditional hard clipping (1n4148) after tone stack (IC pin 6 to ground).