Re: more plex undo questions

[Kim Flint <kflint@annihilist.com>]

an ancient plea for help, discovered on the bottom of all my email:

At 1:31 PM -0700 6/30/97, dan mcmullen wrote:
>hello again,
>
>no replies to my last, somewhat vague query about plex undo behavior, so
>here are a few more specific questions:
>
>- why does the undo led go on at the second repeat of a loop that has just
>been recorded for the first time?

This happens when you are still playing at the time you end the loop. The
echoplex is smart about that, and actually does a small overdub just past
the loop boundary as the input is being turned off. The input is not turned
off abruptly, but very quickly ramped down on the analog side. The result
is that you don't get an ugly pop at the loop boundary.

Since a small overdub was done, the undo function is capable of removing
it. That's why the LED comes on. If you make a loop where you stop the
input before ending the loop, you will see that the LED does not come on.


>- it seems that loops just less than 1/3 of the available time can still
>fail to undo an overdub that crosses the start point.  what is the actual
>percent of total loop time that can always support the two full undos
>necessary to eliminate overdubs that cross over the start point?

This is why expanding the memory in the echoplex is a good idea! You don't
have to worry about things like this anymore. Take a look at the diagrams
about memory use in the Undo section of the manual. That should help you
some.

Each time you do an overdub over a pass of the loop, you use a new section
of memory. If an overdub is done over a loop boundary, you will use two new
sections of memory equal to the loop time. So you have to be careful about
that when you don't have a lot of memory available.

In the cases where you are using almost all the memory, the echoplex often
needs to set aside memory sections to handle situations where you need to
recover from something like an accidental record. I think that may be why
you couldn't undo twice when the loop was 1/3 of the total memory. Matthias
will have to explain that one better, since he knows it better than anyone.


>- the following sequence seems to confuse undo:
>
>  - record a loop
>  - 'accidentally' record over it, but end with undo to cancel the record
>    and return to the first loop
>  - overdub
>
>a long-press undo does not work at this point to remove the overdub.
>short-press undos can remove some of it, depending on where it is.  anyone
>know what's going on here?

You may be hitting a bug in the old software, but I'm not sure. I don't
remember one like that, though. The new software doesn't do this, assuming
you have enough memory available.

You might also be running out of memory, and have a loop that is too long
for an overdub to be undone. This seems more likely. As you're noticeing,
Undo is a feature that becomes much more satisfying when you have plenty of
memory available!

hope this helps,

kim

______________________________________________________________________
Kim Flint                   | Looper's Delight
kflint@annihilist.com       | http://www.annihilist.com/loop/loop.html
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