Emu XL-7 & MP-7 User's Group

> Even when the volume is 0, internal tracks (int or both) that are
> unmuted still have to play the synthesizer.  This is in case the volume
> is turned up while the notes would still be playing.  Therefore, you're
> limited more by the synthesizer.

Sure - and that was what I wanted to test. (Obviously, I had to set
all the other track volumes to zero prior to recording in order to get
a distinct recording of the test pattern.)

> Note also that this is not "drift", it's "jitter".  Drift implies
> cumulative error (i.e. after several minutes, drift adds up).  Jitter
> implies non-cumulative error (i.e. several minutes later, it won't be
> any worse than it was at the beginning).

Sorry - yes, I meant jitter.

> Also, it should be very "deterministic", meaning that the same notes
> each time will be delayed the same amount (or very close).

Yes, it did sound as if there was a pattern to the jitter, which I
assume was just determined by the quantity of (zero-volume) voices
being triggered on higher-priority tracks.

> Right.  Turning the synth *OFF* however, will make large amounts of
> difference.  Try setting all your tracks to ext (not both) except for
> the test track and see how it fares.  This is a more accurate test of
> the *sequencer* alone.

Will do, definitely, although I tend not to use the XL as an external
sequencer (but only as an external MIDI clock).

This is a useful test case to throw at people who complain that "MIDI
is too slow" btw. - usually it's the response times of the devices
that are significant (and the XL-7 is doing a lot when it's triggered,
so it's not surprising). I'm curious: what is the nature of the
communication between the sequencer and the sound engine? Are there
real MIDI messages being passed around internally?

> The sequencer has priority over the arpeggiator.  If you've got other
> notes firing (again regardless of volume) at a given instant, the ones
> from the sequencer will happen first.

OK - again, I guessed that that might be the case.

> The easy way to give the
> arpeggiator a head start is to slide the trigger notes back a tick or
> two in the sequencer.

I'm sure there's a slide data feature somewhere in the pattern editor,
but I'm looking through the manual PDF (and the LCD!) right now and
can't find it...

I don't know whether it's a feature request, but it would be nice to
have some kind of track offset parameter (in ticks?) that could be
applied to a track/pattern without actually altering the data (or the
data position) so that I could play my important 16-note track at
ticks=-1 to force it slightly ahead of the beat. (Otherwise, actually
shifting the events looks ugly in terms of the displayed timings, and
almost certainly screws up the grid/step editor.) I know Vision has
this feature; I don't know about Performer.

> Hope this clarifies stuff a bit!

Absolutely - thanks - and I hope I didn't come down as being too
critical on the machine. I really like using it, but something about
the timing was nagging at the back of my mind and I wanted to know
what it was. I'm more than happy with a 2msec response time so long as
I can achieve that where I need it.

-- 

  nick rothwell -- composition, systems, performance -- http://www.cassiel.com