Wampler Plexi with Trimmers & Soul Kitchen demos

[motterpaul]

Umm...

This is now my fourth pedal demo (previous: Keeley Katana and SupaNova, this one has Soul Kitchen (not boxed) and the Wampler modded Plexi with Trimmers (boxed). That one starts half-way through.

Turn it up (not recorded very loud). The Soul Kitchen is not my thing - compressed sounding and very little headroom (attack on the note) or clean sustain. Sounds good on rhythm, though.
http://tagboardeffects.blogspot.com/search?q=soulkitchen

The Plexi is a great sounding overdrive in my book. Full frequency and steady sustain. You can't really hear the bass boost on my small amp and this camera, but it is very prominent.
http://3.bp.blogspot.com/-I6IpGt9kBYw/Uio9CF2wqCI/AAAAAAAAClg/xqGv1ihaxhQ/s1600/Wampler-Plexi-Drive-mods.png

[Frank_NH]

Both sound great Paul.  Thanks for sharing.  I think my Plexi-Drive will quiet down when it's properly shielded and boxed.  It's sounds very much like yours - loud!

[motterpaul]

Biasing mine was very easy by ear - I got lucky, it just came right up; J201s and 50k trimmers.. I am going to rebox it, though because I have a some leads shorting out and some things I socketed ended up getting kind of loose. I did change the cap for the bass boast cap to 47n AND IT REALLY boosts the low end - maybe too much for a  big amp, but nice for a smaller one.

I might build another just because I have more parts now, like it a lot and I know what I want.

[Frank_NH]

One mod I did on my Plexi-Drive was to change the 470 pF coupling cap off of Q1 to a 1 nF film cap.  Provides a little more bottom end.  I didn't put in a bass boost (which is just adding a larger cap in parallel with the Q1 coupling cap) as I didn't think it needed one.  That would be easy to add later.  I do think the 10 ohm resistor should be increased to 100 ohms, since that is the standard value for power filtering with a 100 uF cap.  I also didn't use metal film resistors (carbon film instead) and that would help with noise overall.

This is the kind of circuit that could be tweaked in a lot of ways, but it's probably about as good as it's going to get for me.  I'm going to move on towards the big prize - the infamous JCM800 emulator!