Bogen Overhaul

Okay, so I was playing around with the Bogen and I finally faced the fact that the preamp was distorting too early and not making enough voltage gain to drive the power tubes to full (clean) output. I've been tossing around the thought of boring out the 7-pin socket hole and putting in a noval socket so I could use a 12AU7 instead of the 6C4 - leave the second the same (as the cathodyne PI) and use the first triode as a recovery gain stage after the cathode follower.

Adding another tube wasn't sitting well with me, and after some consideration I pulled the cathode follower and I'm setting up the preamp as three gain stages:

This is going to have to be tweaked... a lot. I have all the controls in though, so that's something. This preamp should have considerably more headroom, and the overdriven tone should be a lot better, which is good because there's going to be a decent increase in that too. Fitting all that into this chassis is going to be... trying. From here on out, it's going to be turret boards. Turret boards, all the way down.

It's probably going to need more interstage attenuation. Also, now I'm going to reference the heater center tap to the cathodes of the power tubes for a little elevation to help with any noise, as I don't need to worry about a huge Vhk anymore.

It's disappointing that I have to move on from the previous version, but those are the breaks. I'm still planning on doing something with the previous design - maybe a gain stage, then the paralleled stage, then a DC cathode follower, then a recovery stage, then a cathodyne? That's only 3 preamp tubes, might as well add a 4th for reverb. Though I do want to do more work with pentode-based preamps... and that Crate amp that's begging to be turned into a vintage Marshall - I wonder what a Plexi preamp would sound like with a floating paraphase phase inverter? Blues from hell I'm guessing. Not to mention that I haven't even dipped my toe in ultralinear output stages yet.

So many ideas, so few parts.