General Info About Active Pickup Wiring?

[~Maxx]

Hi folks. I'm setting up a partscaster with some Lace Sensors (neck & mid are Golds, bridge is Red/Gold dually) that I had lying around. I've never had active electronics before, and don't know much at all about them - but figured this might be a good occasion to try them out. I'm looking at the Neovin PRE-1 Active preamp from Guitar Fetish. I had intended for this guitar to have only two knobs (master vol & master tone), and I believe (based on the pic at the website) I can still accomplish this while using this preamp. There are some things I'm not sure of though. I'm debating weather I need the full kit, or just the preamp ($5 less - not that that makes much difference). I already have a 250k push/pull pot, and I'm using toggle switches instead of the 5-way. Is 250k alright for this setup? Or are 500k pots required? If I have to use 500k, what effect will that have on my sound when the active circuit is bypassed? Also - I see that the switching output jack in the full kit is rather large. There's no way that it will mount on the back of a standard recessed Strat jack plate without drilling out the cavity (which I'm not opposed to doing - but it's just more work that I'd rather avoid). The preamp alone, however, appears to come with a standard size jack that has the extra connection on it for the battery lead. Anyone know what the difference is (if any)? It looks like the lead from the battery is just a ground. Do you even need a special jack for this? Or can I just solder the black lead from the battery to the jacks sleeve lug?

Sorry for the rambling questions. I guess I just need some specifics on the components so I can decide weather I need the full kit or just the preamp assembly...

Thanks for any input anyone might have!

[KeithHowell]

In an active pickup installation your volume and tone potentiometers will be part of your preamp circuitry and should be specified in the documentation with the preamp and will probably be in the order of 25k to 50k. The preamp will match the usually low impedance of the active pickups to the output to the amp which is generally of a much higher impedance.

The output jack is usually setup so that when you insert a male jack plug it turns the preamp on and vice versa when removing the plug. Generally a stereo socket is used with a male mono plug which will complete the ground circuit on the battery power to the preamp.

Hope that helps?

Keith

[~Maxx]

In an active pickup installation your volume and tone potentiometers will be part of your preamp circuitry and should be specified in the documentation with the preamp and will probably be in the order of 25k to 50k. The preamp will match the usually low impedance of the active pickups to the output to the amp which is generally of a much higher impedance.

The output jack is usually setup so that when you insert a male jack plug it turns the preamp on and vice versa when removing the plug. Generally a stereo socket is used with a male mono plug which will complete the ground circuit on the battery power to the preamp.

Hope that helps?

Keith

Thanks Keith. That does help. Especially the part about the ratings of the pot's. Well... No, actually - it poses a problem. I want to have the option of bypassing the preamp and using the passive circuitry. I definitely can't use 25-50k pots in a standard Strat setup. Would it be detrimental if I were to use 250k pots with the preamp? Are the effects the same as using 500k pots on a Strat (actually 250k pots on a Les Paul would be a better comparison)?

I did notice after I posted that the jack was stereo. Once I realized that it all made perfect sense to me. I think I can get away with using my standard jack though (the shaft and nut are black to match my guitar and jack plate, so I'd rather leave it in place). The description of the kit says that the preamp will be active when the pot is pushed down, and bypassed when it's pulled up. I intend to reverse this function so that passive will be the normal position. This should do well enough to keep me from draining the battery, as I have a solid habit of flipping all my switches to "normal" before I put my guitar down. I do like the idea of the stereo jack though. It's a good fail-safe. Maybe I can track down a black stereo jack.

[KeithHowell]

After I replied to you I had a better look at the links you posted and yes I see they are wiring things with standard pots (250k or 500k) A circuit diagram would be nice to look at.

But reading the blurb it seems that you can just leave your existing (250k or 500k) pots in place and hook up the preamp.

The general rule for pot values is the more windings on the pickup ie higher impedance the higher the pot value. Therefore 250k on strat single coils 500k on humbuckers etc. The higher values shunt less highs to ground thereby brightening up the sound.

I have used a 1M pot on a humbucker to brighten things up on a guitar my neighbour gave me where the humbucker sounded horrible with a 500k pot.

I would however make sure you can switch off power somehow to the preamp else it will be loading the battery continuously even when not in use.

Keith

Edited February 26, 2011 by KeithHowell

[ansil]

unless your using space pickups your ok on the pots.you may notice a little extra chutzpah from larger value pots and active preamp. but the thing to remember is your not using active pickups but a preamp after the fact. which is a different world than using an active pickup and a passive pot. all the talk of pot size now is really irrelevant. a master volume and a master tone are cloudy terms. luckily for use you cleared it up when you wanted to bypass the signal of the preamp. so normal wiring. pickups to switch to normal pots and tone. take the output from the pot and sire it to switch in and out of the preamp circuitry. otherwise you are full on ten all the time and the master volume after the preamp would be a huge difference in dynamics. not necessarily good or bad just different.