making passive blend active?

By active, I'd gather what was meant was that a preamp was used after the pickups, not neccessarily EMG pickups.

Passive blend and V/V controls interact, ie the pickups see a varying load depending on where the control is and this can (sometimes radically) affect tone and output level. In some active systems, there is a buffer amp between each of the pickups and the blend control which if done properly, will eliminate the interaction. Many active systems use the same type of control setup as a passive bass, then simply add a preamp after it. I mainly build my own gear, so I'm not sure which pre to suggest.

Note that "active EQ" and "active pickups" are not the same thing. Most basses that are referred to as "active" have active EQ with passive pickups. But EMG has active pickups as well.

If you're going to use EMG's, you'll need to use one of their circuits as well since EMG's are active pickups. The EMG circuits that have a blend control are called "systems", as opposed to the circuits that have EQ only and are called "controls". So in the EMG line, you'll see, for example, a BTS system and a BTS control; that means bass and treble controls on separate knobs, and the system also has a volume and balance control. EMG's systems have an active (AKA buffered) balance circuit, so they work really well.

For use with passive pickups, there are a few preamps out there that have an active blend circuit. Audere, East (J-Retro and U-retro), Demeter, and I'm pretty sure the new filter-based preamp from AC guitars has an active blend.

Also, you could get a two channel buffer amp from Bartolini and make your own active blend circuit to put in front of any preamp you want (or in front of passive tone control for that matter). The only drawback to this is, if you're also going to have an active preamp, you've got to have enough room in the control cavity for a buffer amp, a preamp, and one or two batteries.

Basically, if you're planning on going to EMG pickups eventually, you'd be best off just waiting and doing the entire electronic package at that time, because any stuff you buy now is going to be useless with EMG active pickups. You can use EMG EQ circuits with any pickups, but their volume/blend circuits only work with their active pickups. Also EMG's EQ and vol/blend controls are very small compared to most other stuff out there, so you don't need a big control cavity for their stuff.

BruceWane said:

Basically, if you're planning on going to EMG pickups eventually, you'd be best off just waiting and doing the entire electronic package at that time, because any stuff you buy now is going to be useless with EMG active pickups. You can use EMG EQ circuits with any pickups, but their volume/blend circuits only work with their active pickups. Also EMG's EQ and vol/blend controls are very small compared to most other stuff out there, so you don't need a big control cavity for their stuff.

Click to expand...

The EMG pups come with the required passive ontrols so you can add the pups then the pre later.

This should fit a passive bass right. The pot is linear (type B, not A). It's good to have an active onboard preamp or buffer after that, because the circuit will cut the signal and raise output impedance.
With active pups or pre-buffered passive ones just divide all the values by 10. Some ground wires not shown - for simplicity.