Re: Jam Man Noise

[Clifford Novey <clifsound@earthlink.net>]

Thanks for the info- I just wish the updates were available- oh well- I 
can live
with it- I turned the output to 1/2 and it was much improved- Thanks-

Cliff

MAT wrote:

> >in the meantime I am excited and having fun using my Jam Man, but I have
> >noticed something that worries me-
> >I noticed some static noise every time a loop began
>
> This is the answer I got from Bob Sellon when I reported a similar 
>problem with
> my Jam Man, I hope it helps to understand...
>
> Miguel
>
>  " There are two possible causes for the noise I can think of; one you
>   can   fix the other you can't.
>
> When Jamman is slaved to an external MIDI clock it determines the
> end of   the loop by itself based on the tempo of the clock and the
> number of   beats selected on the front panel. If the operator tries to 
>end
> the loop   manually, the resulting loop will very likely be shorter
> than it should   be. When the loop is too short, Jamman restarts the
> loop twice: once when   the end of the loop (time) is detected and
> once when the correct number   of MIDI clocks has come in. The
> solution is to let Jamman close the loop   by itself (DON'T tap a
> second time). This will get the loops size to it's   best fit.
>
> The second cause is based on the jitter on the incoming MIDI clocks
> and   the resolution of Jamman itself. At best, Jamman can lock in a
> loop size   to within half a millisecond (512us). The problem is
> that most MIDI clock   sources have jitter (timing variations) in the
> same neighborhood. After   the loop time is locked in, the priority in 
>Jamman is
> to stay in perfect   sync with the incoming MIDI clock.
> The problem is that the combined half   millisecond resolution of Jamman
> and the jitter on the incoming clock   result in the actual size of
> the loop changing very slightly every time   through. As the loop
> size changes, Jamman either shortens the loop or   replays the very
> beginning of the loop to compensate resulting in   potential clicks and 
>pops.
> With the PC itself being slaved the jitter   gets worse
> and so do the clicks and pops.
>
> As I said, there is currently no work-around for this other than, as
> you   said, not playing anything at the loop edge. The only other
> thing I can   suggest (which is equally klugey), is to place
> something percussive at   the splice point which will tend to mask the 
>noise.
> I am looking at the   problem, however, and will let you know if I
> come up with anything.
>
> If anyone out there has any suggestions on how to deal with this,
> I'd love to hear it.
>
>
>      Bob Sellon "