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Discussion in 'Pickups & Electronics [BG]' started by jaguarcat311, Apr 30, 2005.
does anyone have schematics or know where to find schematics for a wal bass onboard pre? Thanks
Good luck. Wals aren't common, the electronics are proprietary (and undoubtedly a big part of their sound) so it's unlikely that you'll get a copy from anyone except the builder himself, should he choose to do so. If you do get them, please email me a copy as I'm very curious what's in there.
Yea i know wals arent too common, they have pretty neat preamps though with a direct out even. the volume has a pull for pick attack which adds some high frequencies and stuff. deffinitely a really neat pre. deffinitely too bad the builder is the only one with schematics.... unless anyone with a wal could take a look at the pre and see whats in it..
Here's 2 useful links if you haven't already seen them.
I replaced a broken Wal pre in a 5 a while back and I remember it as being just parts on a pc board, it should be easy to trace if you can get your hands on one. I've heard they were based on the old Alembic preamp.
Thanks Moo. I had seen them before, but forgot about them. Reading through them now, it certainly describes a circuit similar the the generic Alembic SVF (state variable filter) based filter. The Wal "attack" control is functionally similar to the Alembic "Q" controls, except that it is set internally to a predetermined boost at the roll off, not adjustable by pot or switches on the front of the bass.
Comments based upon this description from the second link.
"The two tone knobs operate electronic low-pass filters whose roll-off frequencies vary with the position of the control. Fully clockwise at 10, the spectrum is full and flat. As the controls are backed off, the spectrums of the appropriate pick-ups are foreshortened (roll-off 12db/octave). Therefore, the dominant tone character varies throughout the entire range of the control. Pulling up the tone knobs produces a quasiparametric boost of about 10db to the harmonics which lie at or near the roll-off frequency set by the rotary position."
So it's likely a pickup - buffer - SVF - Vol/pan - active DI - Tx sort of signal path, needing at least 8 - 10 opamps. Not too hard to duplicate functionally, but whether the chosen parameters in someone else's design would mean it would sound the same is another story. And of course, you can't get the Wal pups....
Ah the Wal pups... Super wide aperture, coil sets for each string actively blended.
Pete actually told me he would sell me the pups and pre about 15 years ago but whenever I tried to buy some he would just ignore me. He has a problem just saying no. Unfortunately it looks like Wal is falling apart from reading the threads in the Wal forum. I hope he passes on the electronics to someone, maybe Sei bass?
By the way, the link in my sig is all Wal bass
Yep, I'm with you. I'm hoping Pete passes on the electronics to someone after he calls it quits. The Wal preamp is cool, but I suspect that it is worthless without the Wal pickups. They were designed to work together.
I exchanged a few emails with someone once who took the pre out of his Wal and used a Bart instead. He was quite happy and sold the pre to someone out there. I made a low offer for it not knowing other people would want it and he told me he had many high buck offers already.
I thought it would make a great stomp box EQ though you would loose some of the cool onboard abilities like setting different EQ for both pups and blending those.