Is My DriveRack PA+ A Fluke?

RichardBlythe

Thanks Gadget for answering my first question about the DRPA+.

Yesterday, I inserted it into my PA rack. When I turned it on, my Senheiser wireless mic receiver went into an awful feedback fit. I quickly turned the DRPA+ off and the problem was gone. I've tried moving the DRPA+ above AND below the Senheiser rackspace with no luck!!! BTW, the reciever only acts up when the DRPA+ is fully inserted into the PA rack.

I've also "tried" to do some web searches this morning about a related issue but have turned up a blank. The DRPA+ is brand new and appears to be working fine. Is there some fluke issue that I've missed?

Dennis

Try changing the transmit and receive frequencies on the mic.

Gadget

Or, sounds like something has a hot chasis...have you tried isolating the driverack frame? If you have a meter you could measure the potential between the 2...

RichardBlythe

Thanks for the two replies!!

I've tried MANY different frequencies with no avail.
There's also no hot chassis issue either. (checked that)

PLEASE tell me something else! I guess I'll have to call, (sigh) customer no-support.

Dennis

RichardBlythe wrote:

There's also no hot chassis issue either. (checked that)

What was your test method to determine that?

RichardBlythe

I've been swamped with my "to-do" list for the past few days, so I've barely been online. Sorry for the delay.

Dennis, the hot-chassis was checked with a Volt-meter. Keep in mind that my other rackunits have behaved perfect for the last few years. The problem has only began when the dbx is powered on.

Gadget

.have you tried isolating the driverack frame?

RichardBlythe

I'm not following you. I've had the dbx partially pulled out of the rack (not touching anything) and it still does it.

Strange as it may seem, last night I transfered the Senheisers to the VERY top of the rack and put the dbx at the VERY bottom. As of right now there is no interference.
It hasn't made me feel too much better because the original interference didn't happen immediately. And no I didn't push any buttons that made it start.

Are you thinking that the dbx is not grounding properly? BTW, I have a recording session for the next two days but I'll try to check back.

Dra

Gadget may be referring to opening the chassis and disconnecting the ground wire from the case.

DRA

Gadget

RichardBlythe, you wrote:

BTW, the reciever only acts up when the DRPA+ is fully inserted into the PA rack.

If the DRPA+ was giving off some RF interference you would have that interference when the DRPA+ was anywhere near the Sennheiser...not just when fully inserted...seems like when the chassis touches the rack, that is when the fun begins...

That's the reason I was thinking that even though you didn't measure a difference of potential, there might be a very slight (read this non measurable with anything other than a micro-amp meter/voltmeter or oscilloscope) difference in the two chassis...the "Isolation" I speak of is "rack ear isolation washers" that keep the chassis of a suspected device from interacting with other devices in the rack. Some equipment, like the Crown Macrotech amps, use a grounded bridge setup... these things can cause interaction in some instances. Could be a leaky cap in any of the devices in the amp rack, it doesn't necessarily mean the DRPA+ is the culprit, just the device that is the impetus...
G

RichardBlythe

It would be a good idea to put some isolation washers between the dbx and the rack. I'll see what that does for me.

Thanks

Dra

Are you using threaded rails or insert nuts types? Also, the cases can't touch. You may need to get some rubber / plastic shelf liner.

DRA

Gadget

Or a couple of strategic pieces of gaffers tape would be fine also.
G