vox berkeley preamp into OD pedal (maybe)

[lopsided]

Hi guys,

I have recently discovered the SMPS for getting high voltage without all the too scary stuff, so I thought I will try a tube project, just for fun and to learn new things.
So I have found this preamp schematic of the old Vox Berkeley http://www.freeinfosociety.com/electronics/schematics/audio/voxberkleypreamp.pdf , which asks for reasonable 150V.

I breadboarded it and fired it up - it worked, but way too fuzzy. Oops, the output is too hot and it overdrives the first stage of my little solid state combo I use for testing, not very nice. I have added a master volume pot - and now nice sound, clean plus a little crunch when the first volume "gain" pot is turned high.

Here is the redrawn schematic I have currently on my breadboard:

I have added the R9 a master pot, to make it a littler less hot, currently I have 680K + 100Kpot (I have heard somewhere small parallel resistance to the tube might cause problems but I will test smaller values too)
I have added a switch with two clipping diodes after the volume switch. I know most tube circuits go for tube distortion exclusively, but I have tried it and think it works nice. Putting it after the pot, allows to control the amount of clipping with the pot.



Still want to try some changes with  the tone circuit and such but I am sharing this in case somebody will find this circuit interesting, but also I would be grateful for any insight or advice from builder more experienced with tubes.

Jakub

[PRR]

> I have heard somewhere small parallel resistance to the tube might cause problems

Less gain, less output, more distortion.

These would be "problems" in most audio uses.

Probably not "problem" for your use.

Won't hurt to try.

[lopsided]

> I have heard somewhere small parallel resistance to the tube might cause problems

Less gain, less output, more distortion.
These would be "problems" in most audio uses.
Probably not "problem" for your use.
Won't hurt to try.

Thanks for the advice, I will try it.
If someone was interested here is a little soundclip, from as it is now.
http://soundcloud.com/lopsided/berkeley-preamp-stompbox
it goes bypass, volume (drive) at 0,50 and 100, diodes on with drive 50 and 100 and then some tonestack fiddling.
Cheap mic, small testing solid-state combo, cool vintage/crappy guitar Eko Manta.