FAQ as such

[The Man Himself <altruist@shoko.CALARTS.EDU>]

This is an admittedly highly shoddy start of an Echoplex FAQ.  I've gone 
through my archive of mail that Kim has sent either to me or via the 
digest and tried to compile it here. 

There are very possibly other problems which are covered elsewhere that I 
don't have archived, so anyone else who has some FAQ material in their 
repositories is encouraged to contribute.

Finally, I've tagged on a few unanswered questions, mostly culled from 
recent posts I've seen floating around the list.

--Andre
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THE LOOPCOPY PARAMETER

Ah, the good old LoopCopy parameter. The parameter itself does nothing in
the current software. What happened there was, the ship date was looming,
the front panels were already done, and the LoopCopy parameter had not been
implemented because we hadn't yet agreed on what it was supposed to do. So
we left if for a future upgrade.

HOWEVER, loop copying is still quite possible! Its done with what we call
"cross functions," where ending one function with a different button press
gives you a special function. In the case of copying audio it's the
Next-Multiply combination when SwitchQuant is on. You can also copy the
time base only with Next-Insert. You do it like this:

Set up multiple loops with the MoreLoops parameter.

Turn SwitchQuant on.

Record a loop in Loop 1.

At some point before the end of the loop, press NextLoop.

You will see the "ooo" display, which means the function is being quantized
to the end of the current cycle time. In the manual, Warren calls this the
"Lame Duck Period." If you do nothing more, the echoplex will switch to
Loop 2 when it reaches the end of the current cycle of Loop 1. We are going
to do something though, since we have several special funcitons available
during this waiting period, one of which is LoopCopy. So:

While the "ooo" display is on, press Multiply.

Now when you reach the end of Loop 1, the echoplex will jump to Loop 2 and
begin copying the audio from Loop 1. You will essentially be in the
multiply function, with Loop 1's audio being multiplied in Loop 2.

While the loop is copying, overdub is essentially on, so any playing you do
is added to the loop. (just like in multiply)

Repetitions of Loop 1 will continue to be added to Loop 2 until you end the
function. (also like multiply)

End the copy by pressing multiply at some point before the end of the last
repetition you want.

The Echoplex will round off to the end of the cycle and begin looping the
copied audio and any overdubs you made. (again, just like multiply)

This seems a bit complicated when written out, but its actually pretty easy
and intuitive to use. I use it all the time, and its one of my favorite
Echoplex functions. I can record 1 bar of music in loop 1, Press
Next-Multiply to start copying it in loop 2, overdub a melody while 4
repetitions of the loop are copied, and end with another press of multiply,
all in just 3 button presses! You can also choose the loop to copy to by
pressing NextLoop several times before pressing multiply. So to copy Loop 1
to Loop 4, I would press Next-Next-Next-Multiply. And it all happens
seemlessly to an observer, so its very usable in musical situations. Give
it a try!

This is actually explained in the manual. Its non-intuitively located in
the description of the SwitchQuant parameter.

In the new upgrade, the mythical LoopCopy parameter has finally become
real. Its function is similar to AutoRecord, where the Echoplex
automatically copies the loop when you switch to a reset loop. The
parameter values are off, sound, and time. Its quite useful in some
situations, although I actually prefer the old way most of the time.

-----------------------
THE INTERNAL COMPRESSOR

Compressor?!

Well, there sort of is, but not really. We have a hardware limiter in 
there,
but it never actually worked right, so we didn't bother to tell anyone 
about
it. I think it might come on at some point, probably keeping an already
distorting signal from distorting even more. 

I think I know a way to modify it so that it does work. I figured that out
shortly before I left g-wiz, since we were planning a minor hardware 
upgrade
at the time to fix emi problems. (I don't think that upgrade has been
implemented, and probably never will.)

It's not a real easy mod, so it's probably not worth the trouble. I'll post
it on the web site some day for all you echoplex hardware hackers. 

As far as input sensitivity, there are some resistor value changes that
adjust the input and output gains that are worth doing. Definitely an 
easier
mod. Basically reduces the input gain so that it is easier to adjust, and
increases the output gain so that you can get signal levels up to +4dbu.

-----------------------
NOISEGATE AND THRESHOLD

The parameter called "threshold" is only for starting a record
when you actually start playing. The noisegate is different. It's on all
the time and has nothing to do with the "threshold" setting. The noisegate
is there to make Undo a much more usable function, so that each press of
Undo takes away a real overdub rather than some unintentional noise. It
also keeps the echoplex from squandering its memory.

Matthias and I have discussed ways to make the noisegate smarter, as well
as adding a parameter for it. Its tricky, since the user can cause himself
troubles with the undo function without realizing it.

---------------------------------------------------
FEEDBACK DEGENERATION WHEN CONTROLS ARE SET TO 100%

This is a problem that was definitely there on prototypes, and at some
point it was fixed. I have to get Matthias' help here, because some of it
was a software problem, and I'm not sure when it got fixed. I know that
with the mythical upgrade, this doesn't happen. Thing is, it doesn't
necessarily happen with the shipping software either. 

My uncertainty is because I think there were several different problems
which caused this. One of them may have been the thermal/cut-the-ic-pin
problem. That particular chip handles both the front panel switches and the
feedback knob, so I think that the same sort of conditions that cause the
Undo button to freak out also might cause loop degrading. I never had a
chance to verify that, so I don't know, but cutting that pin certainly
won't hurt and might fix this for you.

The other bit of uncertainty is that there actually was a software upgrade
very early in the echoplex production. You can see the software version
when you turn the power on, the current software will show LD3 3.2. The
first 60-100 units had an earlier version, LD3 3.0.  Unfortunately, I don't
remember what was fixed in this upgrade. Could have been the loop
degradation, but I don't know. 

-------------------------------
THE THERMAL/IC PIN MODIFICATION

There was a small design error that caused strange behaviors when the
Echoplex was hot. The usual symptom was that pressing the Undo button
would execute Record instead. Basically, a pin on one of the IC's was
connected to +5 volts when it shouldn't have been connected to anything.
This didn't have any effect normally, but when the unit got hot you would
see the problem. Cutting the pin fixes the problem, and the Echoplex works
fine at much higher temperatures. 

Newer units should have this fixed. I don't know which serial numbers would
have the mod, but probably any unit newer than 9 months. You can do the mod
yourself pretty easily if you feel comfortable working on electronics. You
just need to cut pin 5 of U12, the IC with part number ADC0804. If you are
facing the front of the unit, pin 5 would be the 5th pin from the left end
of the chip, on the front panel side.

If you don't think you can do it yourself, any competent electronics tech
should be able to handle it.

---------------------------
PROBLEMS STILL AWAITING EXPLANATION/CLARIFICATION


-- "My first problem with the Echoplex was that static on the foot pedal
would cause the loop contents to be deleted.  Kim has suggested some
grounding approachs that I suspect will help this." 

-- Lately, my problem has been the start point of the loops moving when I
use next loop a lot.  After creating 2 loops, and enhancing them with
multiply and overdub, I nextloop from one multiple in loop 1 to a single
multiple in loop 2, and repeat.  Eventually the start point of these loops
move, and I have to reset the start points manually." 

-- Sound becoming distorted after loop repeated for several days.

-- Echoplex switching into mute mode sporadically after executing 
LoopCopy (cross-function).