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Hello Kim, Again you have come through for me. You helped me out many years ago when I was having problems getting me feedback pedal to work correctly. This removed the problem. Thank you very much. > At 03:53 PM 9/1/2005, muman wrote: > >Hello all, > >After every loop, my EDP makes a quiet thunk sound. I have Loop IV > >and have the memory maxed out. I think it's an early generation > >machine. > > > >Anyone have any suggestions?Louis Hesselt-van-Dinter > > Hi Louis, > > There is a trimpot in the Echoplex that may need to be adjusted in > your unit. It is there for nulling out dc offsets at a VCA, which can > cause this thumping at the loop startpoint. Normally the trimpot is > set at the factory and should not need adjusting, but maybe it got > knocked out of adjustment somehow in your case. > > I posted instructions on how to do this adjustment once long ago, it > is here in the archives: > > http://www.loopers-delight.com/LDarchive/199811/msg00303.html > > However, I realize those instructions need to be updated a little bit > for Echoplexes using LoopIV. So I'll just repost it now, updated for > LoopIV: > > > ********************************************* > How to adjust the Echoplex dc trimpot (LoopIV version): > > This requires that you actually open up the unit, and have it opened > with the power on. *Please follow appropriate electrical safety > rules!!* If you are not careful and you fry yourself, please don't > blame me! > > There's a trimpot on the PCB, near the left side, by the volume knobs. > Its job is to trim a dc offset from a VCA. Sounds like your's is not > set right for some reason, which would cause the thump you hear. > > To set it you need to run one of the built in diagnostic tests. The > test turns the VCA on and off at about 60Hz, so if there is an offset > you can hear the resulting tone in an amplifier. (or see it on a > scope, whichever way you like.) While that test is running, you > adjust the trimmer until the tone/waveform reaches its minimum. > > To get into the trimmer test, power up the unit while holding the > Parameter and Overdub buttons down. The display will show a version > number of the test software at first. When you let go of the buttons, > it should say 7F. > > Press the parameter button so the "Switches" LED is lit (or "Keys" on > older units), then press Insert to start the trimmer test. > > You should hear a ~60Hz tone in an amp. Turning the input volume off, > mix to "loop", and the output volume up helps to hear it if it isn't > obvious. The tone will change in volume as you adjust the trimpot. You > may need a small screwdriver to make the adjustment, depending on the > type of trimpot in your unit. Adjust to where the tone is at it's > lowest level. (you'll still hear hashy noise sounds, but the 60Hz > should become nearly inaudible.) > > After you set the trimmer, pressing parameter again will stop the > test. Then you can turn the echoplex off and power back up normally. > > ********************************************** > > hope this helps, > kim > > > ______________________________________________________________________ > Kim Flint | Looper's Delight > kflint@loopers-delight.com | http://www.loopers-delight.com > > > Louis Hesselt-van-Dinter