Primer on active electronics for bass?

[tfarny]

I'm wondering about putting a preamp into my bass to use with my passive pickups and I probably just need to read something already written rather than ask a whole bunch of questions that have been answered elsewhere. Anyone know of a good thread or link here or elsewhere that explains active circuitry in general, + and -, wiring, battery life, etc? If I did go active I'd need to be able to switch between active and passive, I need to be able to get that good old passive P sound for sure.
I like the simplicity size and reputation of the bartolini two-band on best bass gear, but in general I just need to learn more.
Anyone want to offer directions?

 

[dbw]

I'm a neophyte as well.  I went with a Nordstrand 2.5A/P and hoped for the best... I'm very pleased with it, works great with a MM style pickup.  Single volume and 3 bands of boost/cut, push/pull active/passive and push/pull mid range switches.  I got a double battery box from Warmoth... the Nordstrand can run on 9 or 18 V.  18V provides more headroom but less battery life.  There is absolutely no distortion in 9V operation so I can't imagine what the benefit of 18V is... you can parallel two 9V batteries for double battery life but I only hooked up a single battery, and I use the other slot in the battery box for a spare.

 

[bob7point7]

I am by no means an expert, but I would recommend taking a look at Audere preamps. I have one of their Jazz bass preamps, and I've been pretty happy with it. A few of the unique things:
-Each pickup has its own buffer, then they're blended actively
-You can adjust the impedence that the pickups see to change their voicing
-When the EQ is flat, there is no coloration of the sound

My battery life has been excellent - I think the first battery lasted a year or so. There is also a cool LED that indicates the battery strength each time you plug in the instrument cable.

 

[Patrick from Davis]

I got an Aguilar OBP3 for my last bass project.  9 volts is more than enough for that preamp.  I like it because it is very much just the passive sound when the knobs are at center (no boost or cut)  The wiring is not to difficult, and the active passive switching is easy as well.  This diagram shows the wiring for the volume pot/push-pull to have active or bypass the preamp and have just passive.

http://www.bestbassgear.com/wiring-diagrams/aguilar-volume-pp.pdf

Other than that, " - " is generally ground for DC.  To wire the system to not continually use power (when it is not plugged in), you use a stereo jack for a physical contact switch.  All of the electronics and grounding wires and everything that would go to ground, they go to the center sleeve tab on the jack.  The ground tab on the jack goes only to the battery.  When the cord goes in, it connects the middle and ground with the sleeve of the cord, this connects the battery's ground to the rest of the ground, and the whole circuit is live.

As far as preamps, it is hard to say one over another.  It is like guitars, pickups, amps, pedals, cords, strings, whatever...  Everyone has a favorite.  I would find someone that has a sound you like and start there, if the info is available.
Patrick

 

[Patrick from Davis]

A little clarification on that pdf...

the "to blend" is the hot wire from the pick up
the blue wire is to the pre amp in
the green wire is from the pre amp out
and the tip on the jack is the hot on the jack, not the sleeve.

Patrick