Active Pickups Building Anyone?

[Opencan]

i know the principles of how active pickups work, but never really seen anyone building them as a hobby.

does anyone knows of a source of info about this? such as what gauge of wire to use, what is are the common resistance, any diagrams for the internal pre-amp, types of common used magnets and stuff like that?

I've ran a search and all I got was the basic principles of active pickups being built with weaker magnets, thiker gauge and lower coil resistance while compensating the loss of volume by using an internal pre-amp, but haven't got any info about how to actually make them. sorry if it have been covered before.

thanks in advanced, Ron

[Mike Sulzer]

Building a very small preamp to go in a pickup is not so easy, so the first thing to think about is: why do I want to put the preamp in the pickup? From a circuit point of view, putting the preamp a few inches away is not really any different as long as you connect using shielded cable.

Here are a few things you could do if you design a pickup and preamp to go together:

1. Wind the pickup with a center tap that goes to ground. Then the two ends feed the two inputs on a preamp that is a differential amplifier. This cancels electrical pickup noise very well.

2. Wind a dummy coil* and amplify it with a separate preamp stage, and then add the pickup and dummy signals electronicly. This cancels magnetic hum, but without the treble loss that occurs when you put the dummy coil in series with the pickup.

*Dummy coil design is sometimes not so easy because you need to make a coil with the same sensitivity to magnetic fields as the pickup, but it is best to use a core or cores that have no permanent magnetism.

[Opencan]

Thanks alot for the info

Do you happen to have any schematic for a commonly used pre-amp, or common coil resistance, common coil guage or common magnets being used in active pickups? (i guess alnico won't give the best results)