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Ok I will try out those 47K plate resistors, I suppose that should lower the gain a little as well. And verify which half of v1 is getting the ax7 side.

Hello Again, I thought I would give a little update on this thread, because of the quarantine situation going on I've had loads of time to experiment (and research and read and learn) with this circuit! First of all I have discovered that it is somewhat difficult to keep a preamp with 4 gain stages ...

I just checked out this schematic, yeah not exactly what I wanted. Having the choice of high gain mixed with low gain opens up a lot of cool options with an A-B-Y pedal.

This is interesting, the one thing I would want to know is how they are able to turn off or on the extra gain stage, and still keep the channels in phase. They obviously must have accomplished this as they have a linked input. And the fact that they did it while still using 4 preamp tubes makes me t...

The way I drew it confused me! Thank you Mark I have two preamps I'm going to try, I'm thinking it would be interesting to compare also the difference in the above schematic (the one with an empty v3 triode), one like its drawn where the v3 mixer feeds the tone stack via the cathode and one where th...

Hey Mark, by removing one gain stage from the normal channel wouldn’t it be putting these channels in phase? ie:

Brilliant 3 gain stages -> mixer
Normal 1 gain stage -> mixer

Thanks Mark ...so then let this be the final schematic (maybe) Hybrid Preamp (5 tubes).jpg ....but I just have to ask because its really erking my brain, would the circuit work like this: (thus putting the channels back in-phase and giving you the option of linking them) Hybrid Preamp (5 tubes no v3...

I listened to the sound files. I think the later HJ does not sound very good to my ears, the attack and clarity seems to be gone and it seems to be kind of spitting sound. So personally speaking I would not aspire to capturing this sound. The early HJ sounds pretty much like an OL to me. I still thi...

First off what you've highlighted does not have to do with the cathode bias on v2, so you can ignore my remarks on the differences between bypassed and unbypassed and cold clipping etc. Second I'm not familiar with the schematic you've circled, it looks just like Mark's OL schematic but instead of a...

Clarification, here or between v2 and v3a?

Should it go here, or in between v2 and v3?

Yeah those might be important!

Here is the corrected schematic.

Also see attached for the completed schematic of Mark's idea, which is the more efficient and elegant way of combining these channels. If my translation of his self-biased cathode follower stage is correct, then I will try to finish this mod over the weekend and let you know how it comes out. I am s...

For the couple people paying attention to this thread I thought I would just share with you the results of my testing this weekend. The first thing I tried (because it was an easy 15 minute mod) was to wire it just like the 2nd schematic I attached, where both the normal and the brilliant channel sh...

I'm assuming you are referring to the cathode bias on V2a, on a Biacrown era Hiwatt "OL" model (which also uses the other half of v2) this is biased with a 1k resistor and 47n cap, very similar the HJ. The 22n cap in that position will be very slightly brighter, but the biggest difference ...