Carr Hammerhead

[Mr. Lime]

As the Hammerhead is discontinued I guess we can discuss how the circuit might look like.

There's a video on YT where a schematic is shown but it looks like there are errors on it to confuse some builders or at least let them talk about it.
The gut shot is too low in quality to really see what's going on.
Does someone have a clue how the Hammerhead might look like circuit wise?

The YT video shows basically two gain stages and a paraphase inverter consisting of two parallel triodes.
First gain stage has no cathode resistor shown and the second stage is with 6k8 very cold with little gain.
I don't think having a cathode bypass cap switched in for the inverter stages is a good idea. It would bring the PI out of balance even more.

What do you guys think?

[sluckey]

First gain stage has no cathode resistor

Correct. It's a grid leak bias stage.

[Mr. Lime]

Thanks for the hint, sluckey!

That's new to me, although it's seems to be an old technique - just like the paraphase.
Still I don't get the Grip 4 way switch. Is it supposed to add distortion when the bypass cap is grounded on the inverter stage on position 3 and 4?

[sluckey]

That's new to me, although it's seems to be an old technique - just like the paraphase.
Still I don't get the Grip 4 way switch. Is it supposed to add distortion when the bypass cap is grounded on the inverter stage on position 3 and 4?

The switch simply adds a cathode cap to the various stages. Position 1 has no caps connected to cathodes. Position 2 connects a cathode cap to the first half of the paraphase inverter. Position 3 adds another cathode cap to the second half of the paraphase inverter. Position 4 adds a cathode cap to the output tubes. These cathode caps will increase the gain of the various stages.

[Mr. Lime]

The switch simply adds a cathode cap to the various stages. Position 1 has no caps connected to cathodes. Position 2 connects a cathode cap to the first half of the paraphase inverter. Position 3 adds another cathode cap to the second half of the paraphase inverter. Position 4 adds a cathode cap to the output tubes. These cathode caps will increase the gain of the various stages.

I see that, but the "second" half of the paraphase should only flip the phase and therefore amplify in the same ratio as the signal is padded down by the voltage divider (that acts as a grid leak as well).
As far as I know that amount of imbalance isn't desired in a PI, but that cap would do exactly that at position 3.

[sluckey]

That same imbalance will also be present in position 4. Who says a bit of imbalance is undesirable in a guitar amp? There's far more effort put into bending the guitar waveform than there is in reproducing it perfectly. This just looks like another "tone enhancement" gimmick aimed at your pocketbook.