FAQ 2

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

Here's the latest edition of the Echoplex FAQ!



=====================================================================
the now-legendary CURRENTLY UNAVAILABLE ECHOPLEX UPGRADE (and what it
does)

That's the CU-EU for short....

The bugs are mostly obscure, I think, and for most uses you don't ever
notice them. Things like failing to recognize midi note-offs properly, and
problems with sample dumps to some samplers with weird implementations. One
of the parameters (MuteMode, I think) failed to store itself properly on
powerdown. I think 8ths/beat = 1 had a problem generating midi clock right.
The occasional reverse pops (fairly rare, but annoying when they happen). I
don't have a handy list to paste in here, and those are the noteworthy
things I'm remembering.

Here's some little blurb I sent to someone about it once upon a time:

There are a myriad of bug fixes, numerous minor adjustments and
improvements to existing functions, and some great new features as well.
Some things of interest are: LoopCopy, Multiple Parameter Sets, Sysex
parameter dump, real-time sysex parameter control, noise-gate threshold
control, implementation of midi program change for controlling everthing
with dumb footpedals, greatly improved sync capabilities, and bunches of
other stuff.

----------------------
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.

===========================================================================

ECHOPLEX MIDI SYNCING

Yes, you can have the sequencer generate midi clock, and sync to that. You
can set the length the loop will be in relation to the sequence tempo, so
for instance you can make your loop equal 8 beats, 7 beats, 3 eighths,
whatever. The echoplex, once it is synced, will stay locked to the
sequencer and not drift. This works reasonably well in the current shipping
software, and the not-yet-shipping upgrade has many improvements in this
area.

To do it:

Set the sync parameter to "in"

Make sure you have the echoplex in reset, and midi out from sequencer is in
midi in of the 'plex. Make sure your sequencer is set to generate clocks.

Start the sequencer. It will send midi clocks, which the echoplex will
happily monitor. If you look at the display, you will see a little dot
flash at the sync interval. This interval is determined by the 8ths/beat
parameter, which basically tells the echoplex how many 8th notes will be in
the basic loop cycle.

Press record, the echoplex starts recording. (If you are using the quantize
function, its a bit different. I'll explain below) You have to wait until
after the clock starts to start record. Otherwise the echoplex doesn't know
its supposed to be syncing to something.

Play stuff, press record again. The echoplex will continue recording until
the loop is the appropriate length, end the recording automatically, and
start looping.

Your loop should be in time with your sequence.

If you use the quantize function, which basically quantizes the timing of
your echoplex actions, the echoplex will wait until the next sync interval
to start its recording. This way your loops are not only the proper length,
but the beginning point of the loop is right at the beginning of the
measure in the sequence.

Hopefully that makes some sense. (its quarter to 3am, I'm a tad groggy...)
Play around with it, the practical experience will make it more obvious.

I use this technique for live type playing a lot, to sync my loops to drum
machines. One thing that is fun to experiment with is to use 8ths/beat to
set the meter of your loops to be different from the meter of the sequence.
So you can get 3 verses 4, say. One thing I've had a lot of fun with is to
take a two bar drum machine groove and record it into an echoplex that is
synced to it, with the echoplex's 8ths/beat set to 15, for example. So I
record 15 of the 16 eighths in the drum pattern, and loop that along with
the original. With the loop shifting one eighth each time through, the
simple little drum machine suddenly sounds remarkably creative!

Another thing to try is syncing multiple echoplexes together with different
8ths/beat, to get fripp-like multi loops going where the different loops
are related by some ratio.

Using the echoplex to generate midi clocks and control a sequencer is also
really fun. Basically, set things up the reverse of before. Sync=out, midi
out of echoplex to midi in of sequencer.

Hit record, play your thing, hit record again. The echoplex will then
generate midi clock and send a start-song message to the sequencer. The
sequencer should then start, in time with the thing you just played. I also
do this with drum machines, so the pattern comes in at the tempo I just
played.

I showed Neal Schon how to do this and he went into his studio and riffed
away with his rhythm machine 8 hours a day, every day, for months. (writing
material for the upcoming Journey album that I'm sure you're all dying to
get ;-) ) Its real fun to have the sequence kick in with you like that. Its
just like having a real band, except they actually listen to the tempo you
set and don't mind if you make them start over 300 times while you refine
your guitar riffs.


-------------------------------------------------------------
THE INTERNAL "COMPRESSOR" AND INPUT/OUTPUT GAIN MODIFICATIONS

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. 

The threshold is frequency dependant. So for a full range signal it works,
but for a high pitched or attacky signal, it does not prevent from
distortion. 

The A/D converter can only deal with signals up to a particular amplitude.
Anything beyond that causes ugly distortion. Signals with a lot of high
frequency components tend to distort more. If you are getting distortion
from the echoplex, your input is too loud!!! You should set the input level
so that the loudest signal you ever put in does not cause the converter to
distort. 

The input LED should help you here. You should never see it turn red, that
is much too loud. The best point is for the loudest signal to cause the
input to just turn orange.

There is a circuit in the Echoplex that would be a limiter if it actually
worked. Since it doesn't work, calling it a limiter is not really correct.
In fact, discussing it at all is sort of pointless. The purpose of having
the limiter is to save people who set the levels wrong from experiencing
obnoxious digital distortion in their loops. (make the machine smart so the
user can be stupid)  Limiting just makes the overload condition more
palatable. But really, limiting is still a form of distortion, and if you
were engaging the limiter all the time you would still be complaining about
the sound and I would still be telling you to turn the input level down.

Another solution, which I prefer, is to modify the input so that it has
considerably less gain available. This is easily done by changing a couple
of resistors. That way you are much less likely to turn it up enough to
distort the input. This also makes the input level knob more useful since
more of its range is available. With this mod you also increase the
available output gain to compensate for the lower input. In fact, you
increase the output enough to correct another common echoplex complaint,
which is that the output level is too weak. With the mod the echoplex can
work in -10dBu or +4dBu systems without any problem.

To make the gain changes:

Change R30 from 82.5 K to a 22.1 K 1% metal film resistor
Change R10 from 2.21 K to a 10.0 K 1% metal film resistor

This increases output gain and reduces input gain, respectively.

The input section does have a lot of gain available. Probably too much. The
reason for this was to allow a wide variety of inputs. We thought it would
be great if low level signals, like mics, could be used with the echoplex
without requiring a preamp. In retrospect, this doesn't seem like such a
great idea, since most people using mics or other low level signals have
preamps for them and would probably prefer that over the echoplex preamp
anyway. The number of people having trouble with distortion from turning
the input up too much is probably much greater than the number that found
it useful.

-----------------------
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. 

(Matthias elaborates:)

There is a calculation bug in the feedback path. It appears only after a
lot of repetitions, and only if AutoUndo cannot act, which means: Only if
the loop is longer than half the memory.
The upgrade fixes this.

--------------------------

STATIC FROM THE FOOT PEDAL

This came from Bret Moreland, who lives in Denver, Colorado. The altitude
of that city is very high and the air is very dry. Static electricity is a
very common phenomenon there, much more so than in other parts of the
world. (They also have some truly spectacular lightning)  Electronics
equipment can be quite sensitive to static electric discharges, and Denver
is the sort of place where you discover that. Bret experienced a problem
where a static shock from his foot to the echoplex footpedal caused the
loop to freak out.

I realized this had to do with the manner in which the footpedal chassis is
grounded. Static electic discharges seek the easiest path to earth ground.
When a charge hits the footpedal chassis, it's only path is up the cable
and through the echoplex. This apparently causes a voltage spike which
freaks out the Echoplex's processor.

There are two solutions to this. One is to give a charge hitting the
footpedal chassis an easier path to earth ground than through the rack
unit. You would do this by connecting one end of a grounding strap to the
footpedal chassis and the other end to an earth ground somewhere. (water
pipe, earth ground in the electrical wiring, even the echoplex rack unit's
chassis)

The other solution is to isolate the jack on the footpedal from the
footpedal chassis, so that an electric charge hitting the footpedal chassis
does not have a path to the rack unit. You can do this with isolating
washers or plastic chassis mounting jacks.


-------------------------------
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

"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."