Active/Passive Switch Advice

[elamguitars]

Originally Posted by Stealth

Wire it like this:


This grounds the preamp's input when it's bypassed, so the preamp is amplifying literally nothing and there's no voltage spike once you switch it on.

Wiring courtesy of line6man.

Actually, it is wired like this but I am still getting the popping. I talked to a guy at bestbassgear.com and he suggested installing four 1-meg ohm resistors on the switch.

[bongostealth]

Originally Posted by elamguitars

Actually, it is wired like this but I am still getting the popping. I talked to a guy at bestbassgear.com and he suggested installing four 1-meg ohm resistors on the switch.

1 megohm resistors should do the trick. I installed them on my Aguilar mids push/pull pot and it got rid of 98% of the pop. It won't eliminate it entirely, but then again, if you are installing 4 of them, it just might!

[Cellwelder]

So could I still have 2 control knobs if I plan to run a 3 band preamp? I think those knobs control volume and treble control. I think that is what it is called... All I know that when it is all the way to the left, I get a deeper sound, while the right side is more high ends, or trebles.

[christoph h.]

Hey Cellwelder, your math/logic is flawed.

Currently your bass has two knobs, "volume" and "tone" (or "treble control", as you called it). You will still want those on your bass when you install the preamp. So for a 3-band-preamp you will need to ADD three knobs. So in total, you would have FIVE knobs. (volume, tone, active preamp: treble/mids/bass)

Theoretically, you could replace the current, "passive treble control" with the new treble control of the active preamp, then you would have FOUR knobs in total: volume, active preamp: treble/mids/bass.

But in my experience, a passive treble control (usually called "tone" control) sounds a lot different than reducing the treble on an active preamp, so I would keep both.

Depending on the preamp you get, there are options to keep the knobs to a minimum by using "stacked knobs", but you'll need preamp that is designed/built to support that.

Then you could get away with only THREE knobs, for example: stacked knob for volume & tone, stacked knob for treble/bass, "normal" knob for mids.

There are also knobs that can additionally work like a switch, so called "push/pull knobs" (or "pots").

[Cellwelder]

Guess I'll stick to my two knobs then... But are there active pickups that can run without power by any chance? I know I may be asking stupid questions, but I have only been playing for a year and I enjoy modifying things to make them better...

[Stealth]

Unfortunately, no. A pickup is either passive or active and can't do both.

[Cadfael]

Sorry Stealth ...
A pickup has (is) low impedance or high impedance ...

We also mix these expression in German(y)!

Many people think that active/passive has directly to deal with low/high impedance.
But this is wrong. Okay; 99% of the low impoedance PUs are used with an active electronic - but there are also passive low impedance bass guitars (like "the original" Les Paul basses).

High impedance PUs have many disadvantages regarding noise, but they can easily be used passive and/or active.

Pots for high impedance PUs (most 250k-500k) can be used active and passive as long as they sit between the high impedance PU and the active electronik untit. Between active electronik untit and jack, other pots (most 25-50k) have to be used.
So, an active/passive regulation behind the electronic would only be possible with dual pots with different resistors ...

[Cellwelder]

Thanks for all the help guys, I appreciate it. I guess I'll just get some Dimarzio's or something for now until I get a better guitar to modify...