[Harp-L] Digitech RP100 problem

["Bill" <bill.eborn@xxxxxxxxxxxxxx>]

I believe Tony Eyres mentioned here the other day that he uses an RP100 and I am aware of Richard Hunter's considerable knowledge of the RP250/350.  I picked an RP100 up secondhand last week.  I bought it because i was actually looking for a reverb pedal to go with a buskers amp that doesn't have a built in reverb.  I couldn't find a cheap enough reverb but when i saw the RP100 I thought that might do.  Playing around with it, I've found a pre-set clean sound that I like for the chromatic and using a low z mic, I balanced the impedence before the RP100, using an either an impedance switch or an Art Tube pre-amp.  I'd like to have both options because although it sounds nicer with the pre-amp.  I play a lot in one place in particular where space is at an absolute premium so there I need to try to keep everything as simple as i can, this is why i got the buskers amp in the first place.  

Anyway the problem i've encountered is that after I've been playing for a while, the RP100 starts going haywire, it loses it's setting and starts making a horrible beating noise or it's like I've got two harmonicas playing at the same time.  I'm wondering if it's because I'm balancing the impedence before I get to the unit but i can't see how that would be the case as a guitar would have a hi-z signal going in.  I am as you may have noticed, a complete idiot when it comes to all this technological stuff, so any help would be much appreciated.  

The amp incidentally is an Ashton BSK158, it's equipped with valves apparantly, precisely what type of valves I'm not sure but for the short period before everything goes wrong using the RP100 and the pre-amp, it sounds absolutely bleeding gorgeous! 

Thanks in anticipation 

Bill