Originally Posted by bkbirge
I picked up an old G&L L2000e preamp with harness, all complete from what I can tell, even with the copper plate that holds the switches and pots.
I want to install it into my passive PJ. But... I have no wiring diagram. Any gurus here have docs or are willing to do a step by step? I did a search but I haven't found mention of anyone trying the G&L preamp in other basses, only G&L pickups with other preamps (travesty!).
Anyway, I know my PJ doesn't have all the coil tapping options that a G&L pickup has and that's the main problem, I'm not sure where to wire in the pups to the harness.
Thanks in advance for any pointers!
The preamp wiring diagram as well as that for the L2000 bass are available if you search TB or the "basses by leo" forum.
But as sunbeast points out, you may need to question if you actually want to put it in a P/J bass. It's not a horrible idea, mind you, but understand what it does. If you get the L2000 diagram you'll see that what you have is only a buffer with a slight high boost and a second wiring with even more high boost.
So assuming you install thing on a P/J what do you get? Well there will be an added battery and an added 3 way switch. The switch will choose between passive (the way your P/J is now), active (no EQ just basically a cable buffer with a tad of high boost) and active with highs boosted.
So in passive bass remains as it is at present. IF you are having trouble with long cords to the bass giving you "tone suck" then you can flip into active mode to restore highs. Otherwise passive usually sounds best. And finally if you want to go into a slap frenzy, then flipping to High boost will give a pretty nice slap tone boost. That's it! No bass, treble or mids like a normal preamp.
I've got three L2500 G&L basses and I'll say usually they stay in passive mode though ocasionally for some number I'll go to high boost but it's not often, though often enough I won't take the preamp out like sunbeast. And on occasion I've gotten into a "tone suck" cable situation and the 'active" position does bail you out.
So that is the mystery of "Leo's last circuit". So you have to decide if that is something useful to you. Clearly if you were looking for the standard bass preamp with bass and treble THIS IS NOT IT! In a G&L the bass and treble controls are passive and NOT part of the preamp circuit!