can an onboard preamp (active bass) use passive pickups?

[walterw]

There are some that do 70/70 but then 100/100 is not possible.

fair enough, the A/C blend won't give you both at 100% like an M/N blend would.

still, i have a feeling that the folks who want the sound of both pickups turned down (i.e., isolated from each other) are not the same folks who like the sound of both at 100%, because that would mean a significant volume difference. one blend pot scheme or the other would probably do them fine.

 

[SteveCS]

fair enough, the A/C blend won't give you both at 100% like an M/N blend would.

still, i have a feeling that the folks who want the sound of both pickups turned down (i.e., isolated from each other) are not the same folks who like the sound of both at 100%, because that would mean a significant volume difference. one blend pot scheme or the other would probably do them fine.

Well maybe, but that is their decision, not really mine or anyone else's and I would not presume as to what is generically right for anyone. For me the overriding factor is flexibility, and the price I am willing to pay is having to adjust two knobs in a V/V setup. For some this is too high a price - the overriding factor will be the single-knob adjustment, traded against some compromise in overall tonal flexibility. Really I suppose I want everyone to be clear on the capabilities and constraints of each approach to enable informed decision-making.

PS - Apologies to everyone for the derail...

 

[jazzyvee]

In my bass with a blend i have two internal trim pots, one for each pickup pre-amp so I can determine what percentage of each pickup appears in the bass output. I have adjusted them a number of times to see what I can do with it but as it happens i felt that keeping them both on max works and fine for me.

 

[Passinwind]

well, a blend plus a master volume can.

OK, if your sound is the tone of both pickups isolated from each other and from the output a little bit (including the attendant volume and clarity loss), then yeah, it's not quite the same thing.

if you really wanted to keep that effect, then using an A/C blend would create that isolation loss between the pickups, which i guess would translate to the same kind of sound as a V/V/T with all the knobs turned down a little.

personally i don't miss it. my no-load, ungrounded V/BL/T setup gives a nice sweep without all the output and clarity loss.

Vive la difference.

I've been meaning to try the ungrounded format just to check it out, but I have a zillion more pressing projects going at the moment.

 

[Sub Four]

BTW, an "active pickup" is just a passive (coil) pickup with an embedded preamp.

As example, classic EMG pickups consist of a passive coil pickup combinded with a small integrated preamp unit. Coil and preamp are potted in the pickup enclosure, so they appear as one unit and are referred to as "active pickup". Potted devices are more robust against humidity and vibration and save a bit of space due to the integrated preamp, but are typically beyond economic repair if something fails. Active pickups are also more robust against external electromagnetic interferences (hum).

If you wire up a passive pickup with a preamp you basically get the same result, except that the preamp is not a (physical) part of the pickup as above.
Such a setup requires more shielding/good wiring to protect against hum, than active pickups. Passive pickups with an external preamp are more flexible regarding the configuration, product selection and wiring setup (such as phase/coil tap/serial-parallel switches etc), which can be a big plus depending on the setup you aim for.

A possible drawback of an "active pickup" as described above could be that you cannot install a simple active/passive bypass switch to switch to passive pickup mode if the battery is drained.

 

[iiipopes]

You know, if you are buffering the outputs, using a V-V-T setup, say with an 8/6 blend, it is like turning the balance two or three "notches" towards the pickup you want more output from and lowering the master volume to 8.