hummin noise in active preamp mode

[terjim]

I have a G&L L2000 fretless. I'm wondering if anyone else has had this problem and what they did to fix it?

The bass is from the early 90s. When it's switched into active preamp mode there is a significant hum over the amplifier. If I touch the string, the jack on the lead, or any of the switches or knobs, the hum stops instantly. There is also some fairly loud clicking when I use the switches. The problem does not occur (or a t least can't be detected by my ear) when it is in passive (no preamp) setting.

Also, I tried it on a spare amp and still got the same effect suggesting it is the guitar not the amp. Apart from this long-running problem it is a magic bass.

[dlb1001]

Sounds like a shielding problem. May have to open the control compartment and see if it was shielded properly. Check the sticky in the G&L forum since someone has already looked into this problem.

[sunbeast]

dIf the hum goes away when touching any metal component on the bass, I'm guessing the problem is the outlet your amp is plugged into is not properly grounded (or possibly a power strip or power cord along the line, or even a bad cable- try touching a metal sleeve of the cable to see if that helps). Try touching the chassis of your amp (or any metal component of the amp that should be grounded) and see if that helps (which would signify that the problem is not the bass, but something further down the line). The noise would be worse in active mode because it is A. Higher gain and B. Lower impedance, which = wider frequency response and therefore more noise is audible as well.

Karl