pickup question

[scotty]

I know nothing about the technical aspect of my question. So please be nice.
I would like to know if it is possible to hook up a bill lawrence pickup 500xl to an emg either 81 or 85. Would that be too much for an amp? I would like them to work together instead of on different switches. I am trying to create a sound. I play guitar and have been for a while. I just do not know the technical aspect. Is this at all possble?

[mezarkabul]

short answer: no, somewhat longer answer: you need an active mixer circuit.

[scotty]

short answer: no, somewhat longer answer: you need an active mixer circuit.

is this possible to put one in to a guitar?

[mezarkabul]

not if you cant build it yourself.

you need a custom mixer circuit, not an off-the-shelf one, and preferably a very low noise one. you need to do two things: (1) match the output level of the EMG active pickup, (2) have a low impedance output on that mixer just like EMG's preamp circuitry so that you can use a similar volume pot. You'll also need to figure out if the existing volume pot is usable or not (depends on how complex the existing EMG preamp is and whether you are willing to do some mods on its external wiring). This is a job for an electronics technician.

[Ray Ivers]

Scotty,

Just in case you're interested... here's a couple of links to some EMG products that might help you out:

http://www.emginc.com/displayproduct...2&catalogid=69

http://www.emginc.com/displayproduct...&catalogid=135

If one of these was installed on the Bill Lawrence pickup's output (either can be adjusted for unity gain, apparently) and then its output run to the wiper of a 25K pot - with the output of the EMG 81/85 wired the same - the tops of the two pots could be run to the pickup switch, with the switch output running to the master volume/tone controls (if any) or straight to the output jack. If the Bill Lawrence pickup was lower in output than the EMG, it's output could be boosted 20dB if desired (this is a lot of boost IMO).

I just installed an EMG BQC control set in a Precision, and the installation instructions recommended this output-to-wiper wiring; maybe they've always done so, I really don't recall.

Ray

[mezarkabul]

it's output could be boosted 20dB if desired
Ray

That's a lot of boost for a pickup which already qualifies as "high output".

[Ray Ivers]

it's output could be boosted 20dB if desired (this is a lot of boost IMO).

20dB - I guess that's a lot of boost?

either can be adjusted for unity gain, apparently

...if only the boost could be reduced if needed - like for a high-output pickup or something.

Ray

[Mark Hammer]

Alternatively, install separate output jacks and run the one pickup to one input channel of an amp or mixer, and the other pickup to a second one.

The problem is that their impedances are usually so different that simple passive combination, as found on all those 2-pickup/dual-tone-volume guitars will not work properly.

[David Schwab]

If you run the passive pickup into a buffer, it will match the output impedance of the EMG pickup, which is, more-or-less, just a passive pickup with a buffer.

Here's a simple FET buffer that works great for this:

Stratoblaster Booster

Just insert the buffer between the pickup and the controls. It can be powered from the same battery as the EMG. it has a trim pot for gain, so you can match up the outputs.

I mixed EMG and passive pickups this way in the past.

[Mark Hammer]

Good point. Let me emphasize that EMG pickups, which often have their individual electronics integrated into the pickup "package" itself, are frequently described as uncombinable with passives. If one is thinking of using standard control circuits for passive pickups with such a combination, that assertion is largely true. But as Dave rightly points out, if the overall circuitry recognizes the differences and adapts to them, they CAN be combined, the same way you can plug a passive dynamic mic, a phantom-powered condensor mic, a synth, and a guitar into the same mixing board and it works. It's all in the flexibility of the mixing circuitry and its ability to anticipate such source differences. Once you add a FET buffer/preamp onto a passive pickup, it enters the same league as an EMG and you can apply the same reasonng equally to both.

[David Schwab]

Once you add a FET buffer/preamp onto a passive pickup, it enters the same league as an EMG and you can apply the same reasonng equally to both.

That's the point I want to stress here... a passive pickup followed by a FET (or op amp) buffer is to all intents and purpose, an active pickup. EMG has a few other things going on with the buffer amp, but that's basically all it is.

The problem with mixing passive and active is the difference in output levels and impedances. So the buffer makes them equal in both departments... then they play nicely with one another.

[Mark Hammer]

20dB - I guess that's a lot of boost?

Damn straight.

Boost at the guitar CAN be good, but it can also wreak havoc with vast portions of your signal chain. Most effects pedals are designed around some presumed input levels. Devices like the FETs in phasers or switches, or BBD chips in flangers, choruses, and delays, do NOT stand up well to such punishing levels. The envelope followers in compressors, noise gates, and some things like the old A/DA flanger and CE-1 Chorus also assume certain ranges of signal levels and they are designed accordingly.

All told, if you were running your guitar straight into a power amp, 20db of gain and a low-impedance out would be great. Gievn that most people will stick something in between the guitar and amp, too much gain can be a problematic thing.

[Steve Dallman]

There is a way

At the store I work at, one guitar teacher uses Schector strats from the 80's, each with a couple EMG SA single coils in the middle and neck and an 81 in the bridge.

One of the neck pickups went out and he needed the guitar up and running yesterday.

All we had in the store was a dual blade, humbucking PJMarx pickup.

I made the simplest of op amp buffers to follow the passive pickup. This proved to be too low impedance and was louder than the EMG's.

So I simply added a series resistance after the pickup until I found the value that worked best for the blending. I would suggest putting a trimpot of maybe 250k-1meg and using that as a variable resistor to match the Lawrence with the EMG's.

Then you can stick with the EMG pots, etc.