Conference napalm::commusic_v1

I have never used either of those two synths, but based on my
experience with other synths, the answer is almost certainly yes.
You will need no additional equipment (other than the MIDI cable).

It is possible that you will be able to transmit more than
just notes.  For example, the pitch bend wheel may also be
followed by the other synthesizer.  To get clues about what
is likely to work, check the MIDI documentation for your
two synthesizers.
    John Sauter

Yes you can. In fact that is what MIDI was origianally spec'd to do!
All the other bells and whistles were added later.

	- Rick

P.S. You would connect MIDI out of one machine into MIDI in of the other.
	Then set the send channel of synth 1 and the receive channel of 
	synth 2 to the same thing. Play on!

Last night I parted with the $20 for the cable. Plugged it in to DX-21
out and JX3-P in and, predictably, it worked. While still in experiment
mode, I reversed the connection (JX out, DX in). This also worked. What
surprised me though was the fact I could change preset voices on the DX
by changing them on the JX. Definite 1 for 1. (JX A3 = DX A3, ect.) This
did not work in the opposite direction however. DX out to JX in would
not allow the DX to change the presets on The JX. I can see advantages to
both modes.

JX tape memory did not transmit to DX either.

Next question... If I had another cable, could I use either/both as the
"master" unit by connecting in to out and out to in or would I end up
in some infinite feedback loop? (Or worse, a cloud of smoke?)

All in all, big fun for the cash. These things certainly can get addicting!

Edd

On the Yamaha DX-7 you can tell the machine to transmit or not transmit the
control codes such as patch switching, pitch bend, etc.

So perhaps you just need to set another parameter to do the same on the DX-21.

I believe that you could set up this master/slave ** 2 relationship.

Your Yamaha would not understand the Roland patches anyway, so why bother
sending them?  You actually should be able to send them so that a patch
librarian program could store them on a cheap media such as floppy disk,
but not every synthesizer has this implemented, and the Jx3-p was one of
the earlier midi synths.  Do you have the upgrade to allow velocity sensitivity
for the sound generators in the '3-p?  It still won't allow it from the
keyboard, but some other midi controller with velocity sensitivity could
transmit the information to it (don't know if the DX-21 has this keyboard).

	- Rick

Perhaps I was unclear... I wasn't actually "trading" patches between units,
but rather using the preset patch selecters on the JX to select a different
DX patch. For instance...

        Lets say the DX has a violin patch assigned to selector A1 and a
        brass patch assigned to A2. Lets also say the JX had an organ patch
        at A1 and a piano at A2. If I midi out of the JX to the DX I can
        change the DX patch by pushing the JX selecters.(!?) But it does
        not work in reverse. I'm only using the patches that are inherent
        to the particular machines.

The DX does not have a velocity sensitive keyboard, but it does have the
hard/soft ware to except velocity info from an outboard controller.

Edd

re .5 - The DX may have it's "program change enable" disabled.  This will
be a parameter in the MIDI section.  Some synths allow you to ignore program
change commands coming in over the MIDI part.

You should be able to cross connect both synths with no trouble (i.e., out
of the JX3P into the DX and vice versa).  Remember the definition of MIDI
"out" and "thru" - the out port only sends data originating within the
instrument (i.e., in response to keyboard or front panel actions); the thru
port only sends data that appears at the instrument's MIDI in port.
Generally, synths will not "mix" MIDI data originating within the instrument
and coming in the MIDI in port.  Some sequencers WILL do this optionally -
both my MSQ-100 and MSQ-700 have DIP switches that can convert the "out"
to a "mix" port.  This is very useful in some configurations, but if the
two sequencers get cross connected (I use a JLCooper MSB-1 MIDI switcher in
my setup, so this is possible if I'm shuffling a lot of data around and am
not careful) they will "feedback" and go bonkers.  Recovering from this
often requires breaking the connections and powering them down and up again
(the classic reinitialize strategy).  And data transmitted during the process
(e.g., a transfer from one sequencer to the other) is usually trashed.

So, you can do it as long as the synths don't "mix" internal and MIDI in data.
Your users manual should make this clear.  I doubt very much that a synth would
offer the mix capability - none of mine do.

The tape interface is not designed to transmit data between machines.  It is
strictly intended to save parameter data on tape.  I doubt connnecting the
two machines' tape interfaces together can do any damage, but it's a useless
thing to try.  The tape interface output ("save") may emit a constant carrier\
tone, but usually they don't do *anything* unless told to do so from the front
panel (e.g., go into "tape mode" and "save" or "load").

You can transmit parameter data between compatible machines over the MIDI
ports via the MIDI system exclusive feature.  This is how patch librarians
running on PCs work.  Again, consult your manual.  This may be a faster or
more convenient of copying patches between (compatible) machines than
dumping to tape or a cartridge and reloading the destination machine.  It's
rare for this to be a front panel option.  Sometimes there's a "mode switch"
hidden somewhere (e.g., in my Juno-106, in "mode III" the Juno will send
MIDI exclusive messages whenever any of the front panel sliders or switches
is changed).

len.

oops - re .5 - it would be the JX3P that had it's "program change enable"
disabled.  I.e., either the DX isn't sending it or the JX3P is receiving it and
ignoring it.  Check the MIDI implementation chart for the 3P - I'm sure it
receives and interprets program changes.  Look for a parameter in the MIDI
group (along with send/receive channel) on the front panel.

len.