RE: JamMan sync misconceptions.

["Sellon, Bob" <bsellon@lexicon.com>]

Though the JamMan's output is not switchable (thru/out), there is a
toggle buried in the diagnostics that allows all MIDI clock generation
to be disabled. The following app note describes the operation:

==================================================
Lexicon Jamman - Disable MIDI Clock IN
by Bob Sellon (System Programmer)

This app note was written to allow people to use a special feature in
the released software that was not documented in the Users manual due to
its implementation late in the project.  While ease of use was one of
the primary design parameters of the Jamman, we found that this noble
cause can sometimes result in limited functionality. Design trade offs
are always made but there were some features that just have to be
included at all costs.  When a system is being designed new applications
always turn up at the last minute and you are faced with either leaving
them out or crossing your fingers and adding them in late in the game.
The subject of this app note is just such a feature. 

One group of features that we were able to squeeze into the product was
a fairly moderate MIDI implementation but with excellent MIDI clock
accuracy. Most of the major aspects of the system's operation can be
controlled via MIDI program change messages.  Our original intention for
this was to allow people to use their MIDI foot controllers to control
JamMan. The application we under estimated was the use of a MIDI
sequencer with JamMan. There were two interesting aspects of using a
sequencer with Jamman. First, the sequencer can be preprogram with a
fairly sophesticated sequence of commands making it's use in live
performance automatic and painless,  and second, you can add sequenced
music to your live loops.

While both of these appications can be done without the special feature,
they can be limited by the sequencer itself. If you are content to let
the seuencer set the tempo of your performance, you simply connect the
MIDI OUT of the sequencer to Jamman's MIDI IN as follows:

           Sequencer ----------------> JamMan
                                   MIDI in             

Jamman automatically detects the incoming MIDI clock from the sequencer
(assuming it has been enabled in the sequencer) and attempts to lock to
it. 

The problem shows up if you want to tap the tempo in in real-time but
still use the sequencer to control the Jamman. An example would be
letting sequencer drop in and out of layer mode or initialize
subsequent loops. Again, this can be done without the special feature
but you will be forced to use the sequencer's tempo if the sequencer
cannot disable it output of MIDI clock. The special feature allows you
to disable the input of MIDI clock to Jamman while still recognizing
the control commands. 

To set the system up to allow the tempo to be set in real-time, the MIDI
output from JamMan must be connected to the MIDI input of the sequencer
and the sequencer must be set to derive it's sync externally. 



|---------------------------------------------------------------------|
          | ---->  Sequencer ----------------> JamMan --->------|
                                            MIDI in               MIDI
out
(sorry about the diagrams)
          
The problem is that as soon as JamMan detects a MIDI clock at it's
input, it automatically locks to it. If JamMan is slaved to the
sequencer and the sequencer is slaved to JamMan, who is master?
(Obviously the great god Zarquot.) This is where the spiffy "MIDI Clock
In Disable" feature comes to the rescue. 

Included in the Jamman software is a set of diagnostics which are
typically used by service technicians. Along with the diagnostic tests,
however, there is a utility for changing the MIDI channel to which
the system will respond as well as tool to disable the systems
response to incoming MIDI clocks.

To enter diagnostics, press and hold the RESET/BYPASS and FUNCTION
buttons while the system is powering up. The letter 'd' will appear
on the display indicating that you have entered the diagnostics.
Turn the right hand front panel encoder until the number 12 appears
on the display then press the RESET/BYPASS button. This brings you
to a special diagnostic tool that outputs a very fast MIDI clock
for troubleshooting MIDI problems. If you press the FUNCTION
button, however, the MIDI clock input will be disabled. Press
RESET/BYPASS a second time then turn the encoder to 9 and press
RESET/BYPASS one final time to exit diagnostics and run the normal
software. 

Yes, this is ugly as sin which is one of the reasons it has not shown up
in any application notes so far. But if you are hard core, you just
might find it useful.

One additional down side to this feature and to the setting of the MIDI
channel is that they must be set each time the Jamman is power cycled.
If
the sequencer can optionally disable its output of MIDI clock and also
slave to MIDI clock, the setup step can be avoided all together. Simply
use MIDI channel 1 (Jamman's default) on the sequencer for Jamman data
only and set the sequencer to sync to external MIDI clock with MIDI
clock out disabled.

With MIDI clock IN disabled, the sequencer and JamMan can be connected
as shown above but JamMan will ignore the MIDI clocks being output by
the sequencer and still recognize all of the control commands. With this
setup the operator simply TAPs in the first loop and a whole series of
complex commands can be programmed into the sequencer with no additional
operator intervention except to play their perspective instrument.  

The things that can be done with this setup are amazing. New loops can
be initialized, LAYERING enabled, loops muted, etc... 

Commands from a MIDI foot controller can even be recorded into a
sequencer in real-time using the following setup:


          |----------------<-----MIDI Foot Controller<---------------|
          | ---->  Sequencer ----------------> JamMan -----------|
                                            MIDI in               MIDI
out

The only requirement is that the foot controller passes MIDI clock
through. The Lake Butler Mitigator and the ART foot pedals were found to
work very well for control but tended to be a bit sluggish for setting
the tempo because of the rubber around the buttons.
=====================================================


Bob Sellon
Lexicon/Stec

 

> ----------
> From:         Robert S. Carter[SMTP:rsc4@hhmi.upenn.edu]
> Reply To:     rsc4@hhmi.upenn.edu
> Sent:         Friday, October 10, 1997 1:16 PM
> To:   bsellon@lexicon.com
> Subject:      Re: JamMan sync misconceptions.
> 
> Steven Dubofsky wrote:
> 
> > 
> > Are you sure the JMs out isn't a switchable thru/out? A lot of gear
> that
> > skimps on the midi connectors use this configuration including Boss
> abd
> > Alesis multi effctors.
> > 
> 
> 
> The JamMan MIDI out in fact does act as a MIDI through and echoes all
> info EXCEPT (according to the manual and in my experience) MIDI clock.
> It would obviously be great if it did echo clock as well- whether this
> might bne switchable via some esoteric function the the decvice's
> utility mode, I dunno- no mention of any sort is made in the manual.
> Perhaps our Lexicon buddies can fill us in...
> 
> BOB.
>