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At 04:39 PM 8/1/2003, Hans Lindauer wrote: >I've been slaving my EDP to MIDI sync exclusively for the past few years, >with no trouble. Jon makes a good point - are you leaving overdub open >for long periods of time? > >I don't quite remember the details regarding endless overdubs (I >generally >only overdub short passages), but I do remember hearing that in Loop mode >you need to take it out of overdub periodically. Maybe in Delay mode you >don't (?) - I can't quite remember. > >You just need to punch out and then back into overdub during a silent >part, every so often. Mr. bIz sent me a private mail about this while I was out of town, and I replied without realizing he had also asked about it on the list and started this discussion. Here is what I wrote to him, for those interested: >The echoplex maintains sync by re-triggering the loop whenever it detects >that some drift has occurred. Normally this works fine. However there are >some occasions where this presents a problem, namely when overdub is left >on or when feedback is reduced. If Overdub is on and the sync comes late, >the retriggering will cause a pop to be recorded in the loop. If Overdub >is on and the sync comes early, retriggering will cause the last pass of >overdubbing to be lost. Since both of these possibilities are >unacceptable, the echoplex will instead "free run" while overdub or >feedback are left on. When Overdub is turned off again, it will be again >able to truly sync and retrigger to account for any drifting from the >clock source. > >If you leave Overdub on indefinitely and your clock drifts, then you will >obviously have a problem with the loop getting out of sync. If you simply >turn overdub off once in a while the sync will be maintained. > >For the case of feedback being reduced, there is another thing the >Echoplex does called AutoStartPoint. This is an automatic correction that >the echoplex makes, where it detects that feedback is reduced enough that >the loop is completely changing from the old material. Then, rather than >retriggering the loop and getting a pop or something, it will actually >move the startpoint of the loop slightly to match where the external >clock >has drifted. Then subsequent synching will work normally. > >This is explained in the LoopIV upgrade manual, and in the new Echoplex >Plus manual. It is under "autostartpoint" which is the first thing >explained in the synchronization chapter for the Plus, and towards the >end >of the synchronization chapter in the upgrade manual. > >Note that this problem is not just an echoplex problem. This is more a >laws of time, space, and physics problem. No looper can overdub and >maintain true sync at the same time. Either they have to free run during >that time to avoid audio problems, or they have the audible problems of >pops in the loop, lost overdubs, or weird pitch or time artifacts if it >is >doing time/pitch stretching. bIz also wrote: >>That makes sense. >> >>However, it means that midi synch is totally useless, and I've managed to >>waste a great deal of time over the last couple of years trying to get >the >>box to work and blaming myself, my cables and everything else. which seems like quite an exaggeration to me. It is totally useable, and as many people have pointed out, they are using it just fine. You just need to understand better how it works, so you have an idea of the limitations and how to deal with them. All you need to do is let the loop pass once in a while without any changes being made to it, which most people would normally do anyway. Once you see it does the sync correction, you can go back to overdubbing or feedback or whatever. If you are changing it so constantly that you can never do this, then chances are precise sync will not be such an issue anyway because whatever drifted out of sync would be completely gone or buried within a few repetitions and replaced with whatever new material you are playing. (Presumably you play the new material in rhythm.) This is also related to the "AutoStartPoint" feature of LoopIV mentioned above, which helps correct the startpoint in such situations. It will also help you a lot to understand what the Echoplex is telling you on the front panel. For example, whenever it does a sync correction, it flashes the sync correction LED. This is the second decimal point from the right in the display. (It is subtle by design, because it isn't something most people need to have rudely blinking at them all the time.) Normally you will see this flash once in a while when the clock has drifted a little, but if you don't you know to suspect something is going wrong. Similarly, the leftmost LED indicates when the echoplex does its "AutoUndo" function. This will flash each time a loop passes without any changes being made, and indicates that the echoplex has done a little house-keeping operation called "autoundo" that prevents memory from being wasted or unnecessary Undo presses being required later. If this is never flashing, then changes are happening in the loop every time, which also means that sync corrections can't be made. this is all in the LoopIV upgrade and EDP plus manuals too, btw.... hope this helps, kim ______________________________________________________________________ Kim Flint | Looper's Delight kflint@loopers-delight.com | http://www.loopers-delight.com