pot impedence for active pickups?

[StarryNight]

I was given a SD set of active pickups to install in someone's flying V and according to the SD website the pots used are 100k. Just wondering If anyone can confirm this. Are they so bright that they need a low imedence pot? I've never worked with actives before so excuse the basic questions. He had 500k pots in his guitar hence the confusion.

[Albert Kreuzer]

The main advantage of active pickups is their low output impedance. EMG uses 25k pots. With low impedance outputs you can drive longer cables without losing treble or picking up hum.
With 500k pots you turn the whole thing into a high impedance circuit again (not with the pot full open, but as soon as you turn it back a little).
Of course the 250 or 500k pots will work, but with active pickups lower is better.

Cheers,
Albert

[LtKojak]

I was given a SD set of active pickups to install in someone's flying V and according to the SD website the pots used are 100k. Just wondering If anyone can confirm this. Are they so bright that they need a low imedence pot? I've never worked with actives before so excuse the basic questions. He had 500k pots in his guitar hence the confusion.

In an active circuit the pot value acts as a voltage controller, hence the small values (50K to 150K) needed.

It has no influence on the tone.

[David Schwab]

In an active circuit the pot value acts as a voltage controller, hence the small values (50K to 150K) needed.

It has no influence on the tone.

However, I have found that some EMG pickups sound better with 100K pots. The reason is that the output impedance of some of their pickups is not as low as you might think, and the 25K pots do load the pickup slightly and attenuate the high end.

I did tests back in the early 90's with the pickups wired to a switch box with different value pots. It was very noticeable.

I told them about it at the time, and they said "that shouldn't happen..."

It was easy enough to test though.