Re: more plex undo questions

[matthias@bahianet.com.br (Matthias Grob)]

dan mcmullen asked, ages ago:

>>- 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.

Its very important, when you press UNDO. Once you listened back to the
error, you have to press UNDO twice, since you already created a copy of
the error, when you listened to it. Thats why its 1/3:
- the old "perfect" loop you want to go back to,
- the one you played the error into (the one you are actually listening 
to) and
- the one you are recording to right now.
If you do not overdub or reduce feedback in that last recorded loop, it
will be discarded and you will listen again to the second one.

If the last overdub invaded the beginning of this last recorded loop, it
will be kept, and to go back to the "perfect" loop, it will take one more
in the memory.

If you press UNDO before the error is repeated you should be able to get
rid of it, even if the loops takes almost half the memory.

There are quite a lot of cases. I hope with these informations and the
graphics in the manual you can figure out what happens.
Otherwhise ask more of those nice concrete questions and I might even
answer a little quicker this time. Sorry.


>>- 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?

I think that one is fixed in the upgrade

Matthias