How does active EMG's work ?

[mightyboy88]

Hi guys,

I have always wondered how the active preamp inside EMG actives(81,85,SA,etc) works. I know that they are actually passive pickups that run the signal into a preamp which gives high output and low noise. Something that you cant usually find with passive pickups.

I cant seem to find any data on the internet that describes the mechanics of this preamp circuit. However i have a few ideas on how this may actually be achieved.

1) Using very low(hence quiet) passive pickups and driving the output high by using a booster circuit. The components used in the "boosting" phase must be designed to minimise additional noise to the signal

2) Using a customised passive pickup in which the full frequency spectrum of the pickup's signal output is known. Perhaps a filter may be incorporated into the preamp circuit to eliminate the "bad" frequencies in which feedback tends to occur

3) Using a noise gate-like circuit in the preamp to directly eliminate hum

What do you guys think?

 

[Nicholasim]

I think its option 1.

I've read somewhere before that active pickups (eg EMGs) are very low output passive pickups but boosted with a preamp to get high output with minimal noise. Or something along that line.

I might be wrong though

 

[mightyboy88]

hey nicholas yeah i remember seeing that somewhere too, that would make the most sense too actually hahah

 

[Keitake]

Yep youre right, its something like option 1, ob the inside of the emg is a humbucker that looks like those of a dimarzio x2n in creme colour. They are winded very short as compared to the
Normal humbuckers. The pcp is a booster and since low turns of wires generally makes lesser noise, there are indeed lesser noise. The rest is a resistor and stuff that acts as an equalizer