| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2201.1 | Throw money at it!!! | WEFXEM::COTE | Call *who* Ishmael??? | Tue Dec 12 1989 09:42 | 18 |
| I believe Todd Rhodes (no longer at DEC) built just such a beast. I
don't know how you might get in touch with him.
You may run into a problem using the PM-16. The pads only generate
trigger impulses which are fed to the brain. The brain then maps
the trigger to the appropriate NOTE-ON. I believe ANY signal appearing
at the input will trigger the appropriate voice(s), so a switch BEFORE
the brain doesn't seem like it will accomplish much.
A decided "high tech" approach would be to have a footswitch that
generated program change messages. You could set up 2 HR16 kits.
One with the CHH on a pad, another with the OHH on the same pad.
All other drums remain the same. Toggling back and forth betwixt
the two would get the OHH and CHH on the same PM-16 trigger input.
Probably doesn't help, 'eh?
Edd
|
| 2201.2 | Couple of suggestions | TALK::HARRIMAN | No witty words today | Tue Dec 12 1989 09:49 | 23 |
|
Nice idea.
I'm not sure about the PM16's trigger logic, but if it's like
the PAD-8 then it sees positive logic (i.e. rising edge), which means
that you need to (a) debounce your switch, and (b) keep the unused
side low (grounded or disabled).
You could do it with TTL level logic if you don't care about velocity,
or CMOS analog switches (4016?) whose gates are enabled via the
microswitch poles (appropriately debounced since they aren't
carrying pulse signals, they are high or low)... that would allow
you to get velocity (such as it is) from the crystal transducer.
There are numerous ways to debounce. My favorite is to use a 555 as
a one-shot. You can get a dual 555 (556?) which would do both sides
of the switch. Unfortunately these require power, but it sounds like
the only reliable way to go.
My 2 cents
/pjh
|
| 2201.3 | fuel for the fire ... | DYO780::SCHAFER | Brad - boycott hell. | Tue Dec 12 1989 10:10 | 17 |
| Stupid question - what about wanting to trigger a "partially opened
HH"? Viz:
+--
|
| Open HH
+--
|
| � open HH
+--
|
| Closed HH
+--
I have no idea how to implement in hardware ... sorry.
-b
|
| 2201.4 | I'd like to do this too, with my computer | HPSRAD::NORCROSS | Beauty, Feeling, Play, Creativity | Tue Dec 12 1989 10:11 | 10 |
| This is not a reasonable solution for your problem...
A computer based MIDI mapping program would be appropriate in this case.
The footpedal would be a MIDI Continuous Controller message generator
which qualifies incoming note-on messages. Real time MIDI mapping takes
place based on the last value of the pedal.
Computers are wonderfully flexible.
/Mitch
|
| 2201.5 | Flow chart... | WEFXEM::COTE | Call *who* Ishmael??? | Tue Dec 12 1989 10:11 | 36 |
| ________
|Piezo |___________________________
| Pad | Generic "trigger" pulse |
|______| |<- One of 16 inputs to PM-16
_______|_______
| PM-16 |
|_____________|
| ________
|<- MIDI | |
|_______________| HR16 |
|______|
This might make the delemma (as I see it) easier to understand. The NOTE-ON
the HR-16 needs to see in order to fire the OHH (or CHH) voice is not generated
by the pad, but by the PM-16. All the pads generate the same trigger but are
fed to 1 of 16 inputs on the brain.
The only way I see to do it is to have 3 cables running from the "hi-hat"
to the brain. The FCHH is already dealt with. The logic then becomes how
to get a switch to quietly route the trigger input from one cable to another.
________ _ Switch (if open then 1, else 2)
|Piezo |__|_|_____________________
| Pad | | |<- signal path 1 mapped to OHH
|______| |____________________ | _______ Signal 3 mapped to FCHH
^ ____|__|___|___
Signal path 2 | PM-16 |
mapped to CHH |_____________|
| ________
|<- MIDI | |
|_______________| HR16 |
|______|
The innards of the switch are beyond me.
Edd
|
| 2201.6 | response | TOOK::MCPHERSON | Porgy Tirebiter, a student like you. | Tue Dec 12 1989 18:31 | 83 |
| re: .1
> A decided "high tech" approach would be to have a footswitch that
> generated program change messages. You could set up 2 HR16 kits.
> One with the CHH on a pad, another with the OHH on the same pad.
> All other drums remain the same. Toggling back and forth betwixt
> the two would get the OHH and CHH on the same PM-16 trigger input.
That's actually pretty easy to do. I'll have to try it to see what the
latency is like.... There are 2 jacks on the back of the PM16: one for
program advance and one for program retreat (ok, decrement ;^). They
just rely on a switch that is either NC or NO (I forget) and do their
thing when the circuit either open or closes).
Because each patch (a kit setup) in the PM16 (8 banks of 8 patches
each) comprises not only a pad#_to_midi_note_# map, but also a program
change # that is transmitted over the MIDI i/f on patch select. This
program number tells the HR16 *which* pattern to bring up. The mapping
is a little screwy (but predictable) because of the numbering scheme
mismatch between R-word and A-word.(e.g. program 1 on PM16 brings up
pattern 0 on the Alesis, 2 brings up 1, etc)
re .2
> You could do it with TTL level logic if you don't care about velocity,
> or CMOS analog switches (4016?) whose gates are enabled via the
> microswitch poles (appropriately debounced since they aren't
> carrying pulse signals, they are high or low)... that would allow
> you to get velocity (such as it is) from the crystal transducer.
Actually, I *do* care about velocity since I'm trying to preserve as
much 'nuance' as possible.
The trick I'm trying to pull off is to simply switch between 2 _analog_
signal paths without inducing a false "trigger glitch" on the wire.
I guess I'm being dense, but I don't understand how CMOS or TTL is
going to transmit anything but a Vcc "click" and if so, how does the
output of the pad's piezo map to that in a 1:1 fashion ?
re: .3
>Stupid question - what about wanting to trigger a "partially opened
>HH"?
Stupid answer:
Actually, that's not a stupid question at all, it's a special case of
the basic problem (and one that I would be implementing as soon as I
got the "2 zone" case working).
The basic problem is simply how to build a noiseless switch. Once
that was done, I'd simply wire in another cable to another sensor and
go from a 1x2 to a 1x3 switch, mapping the "middle zone" to the
(thoughtfully provided) "MID HH" on the HR16.
re .4
>This is not a reasonable solution for your problem...
You're right. All of the work I'm trying to do is "pre-MIDI". I.e.
I'm simply trying to mangle/re-route signals from triggers to a
trigger-midi converter based on the position of a pedal...
Ugly, simple hardware problem.
re .5
Nice diagram, Edd, Thanks. I think that synopsizes the signal isuue a
little better.
I think I may cross-post this problem in the ELECTRO_HOBBY conference
tonite or tomorrow and see what shakes out...
As soon as I whip out a few more pads, I think I'll try to see just
_how much_ noise the PM16 will tolerate from a switch before it false
triggers... It is possible to so quite a bit of tweaking on the
individual pad inputs. We'll see,
Well thanks for the input, folks.... I'm still wonderin',,,
/doug
|
| 2201.7 | Analog switch may do the job. | TROA01::HITCHMOUGH | | Wed Dec 13 1989 08:36 | 43 |
| > Actually, I *do* care about velocity since I'm trying to preserve as
> much 'nuance' as possible.
> The trick I'm trying to pull off is to simply switch between 2 _analog_
> signal paths without inducing a false "trigger glitch" on the wire.
> I guess I'm being dense, but I don't understand how CMOS or TTL is
> going to transmit anything but a Vcc "click" and if so, how does the
> output of the pad's piezo map to that in a 1:1 fashion ?
From memory, the 4051 that was mentioned earlier is an analog
multiplexer and actually allows analog signals such as that from
your piezo to be directed to one of 8 possible outputs depending
on the state of 3 control lines. I'm not good at ascii drawing but
I'll have a go:
|----------|
A--------| |
B--------| |
C--------| |-------\
| 4051 | \
| | / 8 analog outputs
| |-------/
i/p --------| |
|---|------|
|
enable-------|
The analog i/p signal is sent to one of 8 outputs depending on the
state of lines ABC, ie from 000 to 111, and the enable line.
Actually the signal is not really sent, but a switch is made between
the i/p and the o/p so the i/p and o/p can actually be reversed.
So, using perhaps switches to sense the position of your pedal
to determine the codes on A and B you can send the piezo o/p to
different inputs on the brain.
Any help?
Ken
|
| 2201.8 | circuits are us | LEDDEV::ROSS | shiver me timbres.... | Wed Dec 13 1989 11:00 | 34 |
|
You dont have a problem. There is no voltage across the
piezo TO create a glitch.
Think about velocity. You're just closing the hi hat.
It in itself makes no sound, right? (If so, it gets
very very complicated....) Lets assume it's just an
on/off situation TO SELECT the input. (of course, the
piezo trigger pulse SHOULD reflect velocity!)
There are some choices on design, and difficult to
show the whole thing in ascii...
The 4051 is a good start, ( or half a 4066 quad switch).
Run off a 9 volt battery...nice. But first, have you
verified that the piezo by itself will trigger the brain?
(lets assume so). Most commercial footswitches close to ground.
Here ya go:
piezo___.______ \___________to brain_in_1
| ^
|_______|______ \_____to brain_in_2
| ^
+v | |
| +--|>o--|
R |
| |
+----DEBOUNCE---+
|
/ (footswitch)
|
gnd
|
| 2201.9 | See June 90 Electronic Musician | TOOK::MCPHERSON | I'm an ADULT now. | Fri May 18 1990 13:48 | 9 |
| For posterity's sake: This identical problem was solved by a guy in the June
Electronic Musician.
Only thing is he used a 9V circuit to trigger the FOOT-CLOSED HH voice on his
drum machine. Seems to me like you'd lose a lot of nuance with the 9v
circuit; you'd have the FC-HH the same exact volume all the time (at least
until it started to run down... ;^))
/doug
|