Has anyone else noticed this problem?
I have a Yamaha RBX 765A active bass that has a long threaded barrel stereo output jack. The problem is that when I use a cable with a straight plug, if the plug is bumped or pushed sideways somehow, there's sometimes a gut-wrenching pop similar to what happens if you - accidentally, of course - unplug without muting or switching off the amp first.
The jack looks similar to a Switchcraft #152B stereo jack, but I can't tell for sure. Most of my cables have Neutrik plugs, but the problem occurs with all types of plugs (including Switchcraft and "cheapies") and with different cables.
My solution, so far, is to use a right-angle plug, so it doesn't get hit, but I'm wondering whether the behavior is typical of long barrel jacks in general or whether it's a defect of some sort. Is there a better quality jack that might help?
Yamaha used the usual trick of wiring the pre-amp battery negative terminal to the ring terminal on the stereo jack so that the preamp gets power when a mono plug is inserted (an industry standard bad idea IMO
). I'm guessing that, when the plug gets moved sideways, the jack tip and ring terminals are shorting internally - putting 9V on the tip and into the amp input.
The jack is installed in a hole that's drilled through to the pre-amp control cavity, so using a different type of jack really isn't an option; I'm stuck with the long-barrel type.
Thanks for reading - suggestions and advice welcome.