DRRI Overhaul

[ajeffcote]

My Fender DRRI just did not sound like I wanted it to,so I'm replacing the PC board with a Hoffman turret style board.I am putting a ground buss across all the pots and input jacks as per the Hoffman instructions.
My question is should I install insulators between the guitar input jacks and the chassis since the jacks are grounded to the buss?If I don't,will that increase the possibility of picking up unwanted noise via the chassis as a ground loop?The buss will be grounded to the chassis also.

[MWJB]

You shouldn't need to isolate the jacks, Fender (& countless others) never did. Ground the buss wire to the chassis via Normal #1 input jack.

[Rick Erickson]

You might try replacing the stock 12AX7WA tubes first. Could save you a LOT of time and energy. What's the advantage of a ground buss across the pots? It never worked well in Marshall amps, why put a bad idea into your Fender?

RE

[ajeffcote]

Sorry it took so long for me to get back to this post.What problems are associated with using the ground buss across the pots?I didn't know any better and that's how I wired it up.Seems to be OK.The amp is pretty quiet.My pots are not isolated from the chassis so I guess the buss is not really functional.

[MWJB]

"What problems are associated with using the ground buss across the pots?" None. It works fine for me and many, many others.

[Rick Erickson]

[What problems are associated with using the ground buss across the pots?]

The backshell of most all pots are press fit to the front, which is press fit to the bushing which gets secured to the chassis, so there are al least two points which will become loose and/or corroded over time. This creates resistance to ground (chassis) which results in a less than ideal ground situation. I have serviced many Marshall amps where this has resulted in excessive hum and degraded tone. Fender amps can develop a similar problem when the brass ground strip corrodes and no longer makes good contact to the chassis. The simple cure here is to remove the Brass plate, clean and polish both mating surfaces and re-assemble.

RE

[Bruce / Mission Amps]

[What problems are associated with using the ground buss across the pots?]

The backshell of most all pots are press fit to the front, which is press fit to the bushing which gets secured to the chassis, so there are al least two points which will become loose and/or corroded over time. This creates resistance to ground (chassis) which results in a less than ideal ground situation. I have serviced many Marshall amps where this has resulted in excessive hum and degraded tone. Fender amps can develop a similar problem when the brass ground strip corrodes and no longer makes good contact to the chassis. The simple cure here is to remove the Brass plate, clean and polish both mating surfaces and re-assemble.

RE

With respect to the Fender brass plate... I have found that simply removing the knobs, loosening the bushing nuts on the input jacks and pots, followed by rotating and jiggling the pots when semi snug and then retightening them all... fixes that about 95% of the time.