"Ben Bradley" wrote in message
...


Ok, well it looks like I need to make a distinction, which I've been
trying
to do, and I thought was thorough - they look exactly like MIDI cables,
they
are plugged into female jacks at either end marked "MIDI",

Whoa... where are these jacks? What equipment are they on?


One end is on the teacher's console (which is connected to a headset
phones/mic combo), the other end is on a little black box that also contains
headphone in and out jacks, as well as a mic in jack, but they are not
directly connected to any MIDI jacks like on the Cavinova.

Are any
of these jacks regular commercial gear, or is it all some sort of
custom manufacture?

Well, I'm going to look tonight at the manufacturer, but I would bet it's a
small-ish company making them slowly - like how people with a little shop
make guitar pedals. But the Teacher's console looks as good as anything
Yamaha or Roland puts out. The headphone box at the other end is more
suspect - it's just one of those folded metal things (like Guitar pedals,
which I know are manufactured as "blanks" and people can order them with X
holes and various configurations) which simply have the jacks in them. But
I'll find out tonight.

Now my impression is that you have "MIDI cables" that connect to
5-pin female "DIN" connectors (just like the old IBM PC/XT/AT keyboard
connector) that carry audio, but the jacks are marked "MIDI" even
though they don't carry MIDI.

yes, that's what I think too.

I think this just might be a violation
of the MIDI standardd...

So, do I call the MIDI police! It may be a violation of the MIDI standard
(using MIDI cables for audio transmission), but if that's what's happening
(and it must be), could that be likely be causing the hum problem? And why -
is it unlikely that this little box is ungrounded/unshielded, etc.???

[snip]

Any time a cable carries something other than the most common,
'normal' signal (or in this case, the ONLY signal until this thread
came up) for it, confusion is more likely than otherwise. The fact
that the jacks are actually MARKED "MIDI" doesn't just increase the
chances manifold, it just about guarantees confusion.

Yes, I noticed :-)

My personal beef is 1/4" phone connectors for amplifier outputs and
speakers. It allows you to physically plug an electric guitar into and
amplifier output or a speaker, but it doesn't make sense so do so. Too
many people with access to that kind of equipment aren't very
knowledgable, likely to have hangovers, etc.

YOu don't know how many times I've seen Marshall amps fried because a
guitarist put a guitar cable from the speaker outs into the cabinet. First
thing I teach my student assistants is the difference between cables and
where they can and can't go (at least to the extent of my knowledge and the
uses we have for them).

Thanks Ben, I'll let you know what other info I can dig up. Once again, I
appreciate everyone's time, assistance, and patience

Steve

"Scott Dorsey" wrote in message
...
Steve Latham wrote:

Wow - I didn't know that. But I suppose a female MIDI jack could be wired
so
that all 5 pins (if you wanted to) were actually connected to carry audio
instead?

Yes, but then it wouldn't be a MIDI cable,

well, if it was purchased form a store in a bag that said "MIDI" cable, I'd
call it that even if it carried audio (unless of course I was using it and
knew it was audio)

it would be a DIN-5 audio cable.

That makes sense, and I'll use that distinction from now on. Thanks for that
info.

And it wouldn't be marked MIDI on the jack, it would marked LINE IN

(this one's not unfortunately - maybe they were trying to keep it simple for
music teachers who might already be familiar with MIDI cables)

and
it would be wired with pin 2 grounded, and signal on pin 1 and 3. Totally
different thing, completely unrelated. They use the same connectors, but
are not MIDI (and in fact predate MIDI by twenty years). You hardly see
that any longer but it was one of the original uses of the DIN connectors
back in the fifties.

Now this is really interesting. I love info like this.


If you have something marked MIDI on the input and something marked MIDI
on the output, my guess is that it's probably MIDI that you are dealing
with.

It can't be though. There's no MIDI coming from anything. It's
Clavinova Headphone Jack Out -Black Box HP IN - The black box has four
jacks, Jack 1 is the aforementioned HP IN (actually, this one is hard
wired). Jack 2 is HP Out (to the headset phones) Jack 3 is the line in from
the mic on the headset, and Jack 4 is marked "MIDI" (I can't remember if it
says out or in, but it's irrelevant). This "MIDI" Jack uses what I've been
calling a "MIDI Cable" to connect with another jack also marked "MIDI" on
the teacher's console. But these cables marked "MIDI" are not actually
hooked up to the Clavinova's MIDI In/Out - it only goes to this little box
which is ultimately only attached to the Clav's HP out, and the headset,
hence audio only.

My belief is that these little boxes are wired so that the output from the
student's mic, and the Clav (audio from the HP jack) can be heard by both
the teacher and the student, and for some reason, some type of cable needed
to be used (rather than 1/4 "guitar" cable, RCA cable, Coax, XLR, or
whatever). Maybe they needed more hot leads - one for HP, and one for MIC,
and of course the HP are in stereo, so I would assume at least 2 hots and
one ground, or possibly 3 hots and one ground (though I see no reason the
Mic signal would have to have it's own line, unless there's some phantom
power or something else involved that I can't see because it's inside the
boxes). Now I've got standard Headset packages that run on XLR - whic is
three wires right - one ground, 2 leads (and aren't they out of phase
allowing for low impedance and/or "balanced" signal, and/or longer runs with
less interference.

My guess is that all of this is unbalanced (headphone jacks are unbalanced,
aren't they), and for some reason, XLR wouldn't do, and they either needed a
third lead, or were afraid XLR cables would confuse people (or the jacks
were more expensive), so they built this contraption with off the shelf
female "MIDI" jacks (are they may have been 5 din audio and they just marked
the "MIDI" on the boxes to avoid confusing teachers who would likely be far
more familiar with MIDI cables rather than 5 din audio cables).

Thanks,
Steve

Steve Latham wrote:

well, if it was purchased form a store in a bag that said "MIDI" cable, I'd
call it that even if it carried audio (unless of course I was using it and
knew it was audio)

MIDI cables are usually unshielded. If you use a MIDI cable for baseband
audio, it will probably hum. Just because it has the same style connectors
does not mean it is the same cable.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Yes, as I've now discovered! Please see my Yamaha MLC100 thread(s) for the
continuing saga!

Thanks,

"Scott Dorsey" wrote in message
...
Steve Latham wrote:

well, if it was purchased form a store in a bag that said "MIDI" cable,
I'd
call it that even if it carried audio (unless of course I was using it and
knew it was audio)

MIDI cables are usually unshielded. If you use a MIDI cable for baseband
audio, it will probably hum. Just because it has the same style
connectors
does not mean it is the same cable.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."