[Harp-L] Feedback on RP150

[Richard Hunter <turtlehill@xxxxxxxxxxxxx>]

I've been wondering what Martin Oldberg's problem is with feedback on his RP150.  The fact is that none of my other customers has ever had this kind of issue, where the RP150 is producing big feedback no matter what it's plugged into.  So here's a short list of stuff for Martin to consider.

1)  First, and I know this is ridiculously obvious, are you sure that you actually loaded my patches into the device?  The factory patches--i.e. the ones my patches overwrite--are certain to produce walls of feedback every time. The RP150 only gives you a two-digit display to tell you what patch you're on, so it would be easy to play a factory patch without knowing it.  Which leads us to item number two:

2)  Assuming you did in fact load my patches, are you playing mine, or the factory patches?  The RP has two parts to its memory.  One part of the memory is the user area, which is where my patches go.  The other part is read-only factory memory, which remains in place whether my patches are loaded or not. (Out of the factory, user memory contains the same stuff that's in factory memory--my patches overwrite the user memory.)   Again, because the RP150's display is just two digits, and those digits are the same for the relative locations in both user and factory memory (e.g. there's a location 25 in user memory and a location 25 in factory memory), you could easily be playing the patches in factory memory without knowing it, even if my patches are loaded.  If so, you will indeed get a lot of feedback.

The solution to both these issues is the same: 1) make sure my patches are loaded by checking the XEDIT window when you do the load to make sure mine are in there, and 2) make sure you're using the patches in user memory when you play.

BY the way, note that anyone using an RP250 or up doesn't have that problem, because those devices give you a display that's long enough to see the patch name, as opposed to a number.

3) If you mic is a lo-z mic, do you have an XLR cable with a lo-z to hi-z transformer on it?
4) Are you using the correct output jack?   The RPs have left and right 1/4" output jacks.  If you use the right jack by itself, bad things happen.  Make sure your output cable is plugged into the jack that reads LEFT/MONO.

There are a few things I know for sure:: 1) under normal operating conditions the RP patches I supply don't feed back at anything close to normal performing volume, 2) you're getting this problem on multiple PA systems, so it's not the PA unless you're making the same mistake with every PA system (which of course is possible).  So it seems to me that one of the issues described above is the likely culprit, meaning that somehow you're playing the patches in factory memory instead of mine, or you're connecting the output cable to the wrong jack.  From previous conversations I think you've dealt with the mic cable issue by now, and anyway you'd have the opposite problem--very low output--if you were using a lo-z cable without a transformer.  Check the output jack to make sure you're using the LEFT/MONO output, use the footpedal up and down switches to navigate to user memory (you can make sure by navigating to one of my patches that uses vibrato or rotary--those are pretty hard to mistake for anything in the factory set), and see if the problem goes away. 

Regards, Richard Hunter 

author, "Jazz Harp" (Oak Publications, NYC)
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