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Alesis Andromeda - how to implement polyphonic aftertouch


The Real MC

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I have found a way to implement polyphonic aftertouch on the Alesis Andromeda using a MIDI controller with monophonic aftertouch.

 

You need a MIDI controller with mono aftertouch and the ability to transmit in MIDI Mode 4. MIDI Mode 4 is an accumulative monophonic mode, which means the MIDI controller will send key 1 on MIDI channel (n), key 2 on MIDI channel (n+1), key 3 on MIDI channel (n+2), etc. Your controller may have an option for number of MIDI channels in Mode 4, IE you can specify an upper limit of channel 8 so that other devices on channel 9 and up are not affected.

 

Say your Andromeda MIDI base channel under the Globals menu is channel 1. You want channel (n) on the MIDI controller to be channel #1. Under this configuration when you press keys and engage the aftertouch, your MIDI controller should send note on and mono aftertouch messages on MIDI channel 1 for key #1, the next key will be MIDI channel 2, the next key will be MIDI channel 3, etc. Every key will have its independent MIDI channel and mono aftertouch - an alternate poly aftertouch.

 

Configure a patch on the Andromeda that uses MIDI Aftertouch to modulate something - like the filter cutoff. MIDI controller mono aftertouch is equal to "MIDI Aftertouch" in the Andromeda modulation source list.

 

The Andromeda does not appear to have a MIDI Mode 4 so we need to configure a mix setup on the Andromeda with (n) layers, every layer playing the aforementioned patch. Layer one is assigned MIDI channel n, layer 2 = MIDI channel n+1, layer 3 = MIDI channel n+2, etc.

 

Unfortunately for Kurzweil MIDIBoard owners, there is a bug in the firmware in that all mono aftertouch messages are only transmitted on the first MIDI channel (d@mn!). Another MIDI controller may operate correctly.

 

But I did prove this concept by multitracking MIDI tracks on my seqeuncer using my MIDIBoard on different MIDI channels - and this works!

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I have found a way to implement polyphonic aftertouch on the Alesis Andromeda using a MIDI controller with monophonic aftertouch.

 

You need a MIDI controller with mono aftertouch and the ability to transmit in MIDI Mode 4. MIDI Mode 4 is an accumulative monophonic mode, which means the MIDI controller will send key 1 on MIDI channel (n), key 2 on MIDI channel (n+1), key 3 on MIDI channel (n+2), etc. Your controller may have an option for number of MIDI channels in Mode 4, IE you can specify an upper limit of channel 8 so that other devices on channel 9 and up are not affected.

 

Say your Andromeda MIDI base channel under the Globals menu is channel 1. You want channel (n) on the MIDI controller to be channel #1. Under this configuration when you press keys and engage the aftertouch, your MIDI controller should send note on and mono aftertouch messages on MIDI channel 1 for key #1, the next key will be MIDI channel 2, the next key will be MIDI channel 3, etc. Every key will have its independent MIDI channel and mono aftertouch - an alternate poly aftertouch.

 

I must have got it wrong somewhere - hope you can help clarify things. I thought Poly AT meant - with 10 fingers, you can send 10 note numbers, 10 note velocities, and 10 aftertouch values simultaneously. Going by your idea, you'd still have only 1 aftertouch value transmitted/recieved at a time, right? I don't have any experience with Poly AT, so apologies for the naive question! But your idea does seem interesting...

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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Going by your idea, you'd still have only 1 aftertouch value transmitted/recieved at a time, right?

 

He's saying that each note being played would happen on a separate MIDI channel, thereby fooling the Andromeda into accepting separate AT control values for each note. It's not true Poly AT, it's multi-channel AT. The end result would sound like Poly AT, though.

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It's really a shame true polyphonic aftertouch was never programmed into the OS as Alesis promised it would be. In the back of my mind I'm hoping that some day in the future, some intrepid soul will reverse engineer the OS and program it in. After all, if somebody can retrofit the Korg DSS-1 sampler and the JX3p with new capabilities, then why not?
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It's really a shame true polyphonic aftertouch was never programmed into the OS as Alesis promised it would be.

 

At least they didn't leave it with as many unresolved issues as my Fusion! Seems lok they just run out of resources and give up on these potentially great products.

Dan

 

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.

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Going by your idea, you'd still have only 1 aftertouch value transmitted/recieved at a time, right?

 

He's saying that each note being played would happen on a separate MIDI channel, thereby fooling the Andromeda into accepting separate AT control values for each note. It's not true Poly AT, it's multi-channel AT. The end result would sound like Poly AT, though.

Thanks - got it now. Cool, The Real MC... :thu:

Question - in Midi Mode 4, what about PitchBend? Does the PB channel change with each note? Now that might be fun...

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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Going by your idea, you'd still have only 1 aftertouch value transmitted/recieved at a time, right?

 

He's saying that each note being played would happen on a separate MIDI channel, thereby fooling the Andromeda into accepting separate AT control values for each note. It's not true Poly AT, it's multi-channel AT. The end result would sound like Poly AT, though.

Thanks - got it now. Cool, The Real MC... :thu:

Question - in Midi Mode 4, what about PitchBend? Does the PB channel change with each note? Now that might be fun...

 

YES this is what many guitar-to-midi converters do

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So - does anybody know of a keyboard that can operate in midi mode 4, or is it just as rare as a board with poly AT?
Nord Stage 3 sw73, Yamaha CP88, KeyB Legend Live, Kurzweil PC3K7, EV ZXa1 + sub. K&M stands, Hammond E112, Leslie 3300, EHX V256, Roland SE-02, Yamaha EX5R & TG77, Novation Nova desktop & much more...
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So - does anybody know of a keyboard that can operate in midi mode 4, or is it just as rare as a board with poly AT?

I don't know how many keyboards can operate in Midi Mode 4. However, those of us who gig with a laptop can easily reap the benefits of The Real MC's discovery :cool:. Also studio musicians, of course. Doesn't have to be with VSTs, either - the laptop could be used for midi processing only, with sounds from an external hardware module. Nice thing is, any keyboard with aftertouch will do, and the sound engine/module/vst need not be Poly AT-compatible.

 

BTW, if aftertouch isnt available, you could still use the idea to have "pseudo-polyphonic pitchbend", described above. Sustain a chord with a pedal, and you can bend only the last note played, without affecting the chord :rawk:.

 

EDIT: Just realized - the module/keyboard/softsynth would need to (a) listen in on many channels simultaneously and (b) aftertouch/pitchbend on a given channel should affect only the notes on that channel. The controller need not support Midi Mode 4.

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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A MIDI solutions Event Processor says it can step through a sequence of MIDI events in response to MIDI signals. When it gets to the end of the list of the events, it can be set to loop back to the start.

 

So... could you use one to change MIDI channel each time it receives a note-on message? In sequence 1,2,3 etc to fake polyphonic aftertouch as is being discussed?

 

I've not got an Event Processor so I probably have misunderstood what it does - but I'm intrigued by the possibilities.

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EDIT: Just realized - the module/keyboard/softsynth would need to (a) have an omni mode, i.e. listen in on many channels simultaneously

 

Careful; Omni Mode means that it'll respond to MIDI messages regardless of the channel the message appears on. This is not what you want to happen. What it needs is to simply respond to multiple MIDI channels, but this is not what the term "Omni Mode" means in the MIDI specification.

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Careful; Omni Mode means that it'll respond to MIDI messages regardless of the channel the message appears on. This is not what you want to happen. What it needs is to simply respond to multiple MIDI channels, but this is not what the term "Omni Mode" means in the MIDI specification.

Thanks for the heads-up, SG. I'm guessing, 'true' Omni Mode would make all held notes respond to AT/PB on all channels, correct? My condition (b) rules this out, but it's always better to follow conventions, and leave less scope for confusion. Post edited.

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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So - does anybody know of a keyboard that can operate in midi mode 4, or is it just as rare as a board with poly AT?

I don't know how many keyboards can operate in Midi Mode 4. However, those of us who gig with a laptop can easily reap the benefits of The Real MC's discovery :cool:. Also studio musicians, of course. Doesn't have to be with VSTs, either - the laptop could be used for midi processing only, with sounds from an external hardware module. Nice thing is, any keyboard with aftertouch will do, and the sound engine/module/vst need not be Poly AT-compatible.

 

BTW, if aftertouch isnt available, you could still use the idea to have "pseudo-polyphonic pitchbend", described above. Sustain a chord with a pedal, and you can bend only the last note played, without affecting the chord :rawk:.

 

EDIT: Just realized - the module/keyboard/softsynth would need to (a) listen in on many channels simultaneously and (b) aftertouch/pitchbend on a given channel should affect only the notes on that channel. The controller need not support Midi Mode 4.

OK, I guess I don't understand it at all.

 

If the controller supports only channel aftertouch, how do you get per-note aftertouch, without transmitting using mode 4?

 

The way I figured it, the controller would be in mode 4. It would need the same hardware as needed for poly aftertouch -- that is, independent pressure sensitivity per-key. (You'd also need this to support channel aftertouch with zones.)

 

In mode 4, the controller would send channel aftertouch individually for each channel, and since each channel maps to one note, bingo. The rest of the magic is at the receiving end, just having the same patch on all channels. (Note: limited to 16-note polyphony.)

 

Without using mode 4 on the controller, I have no idea how this would work. I can't get around the fact that pressing ANY key changes the channel aftertouch, which would affect all notes on the channel. You could split the notes to channels later, but which channel would you assign the cannel aftertouch to?

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OK, I guess I don't understand it at all.

 

If the controller supports only channel aftertouch, how do you get per-note aftertouch, without transmitting using mode 4?

 

The way I figured it, the controller would be in mode 4. It would need the same hardware as needed for poly aftertouch -- that is, independent pressure sensitivity per-key. (You'd also need this to support channel aftertouch with zones.)

 

In mode 4, the controller would send channel aftertouch individually for each channel, and since each channel maps to one note, bingo. The rest of the magic is at the receiving end, just having the same patch on all channels. (Note: limited to 16-note polyphony.)

 

Without using mode 4 on the controller, I have no idea how this would work. I can't get around the fact that pressing ANY key changes the channel aftertouch, which would affect all notes on the channel. You could split the notes to channels later, but which channel would you assign the cannel aftertouch to?

Jeff, till just a few hours ago, I had the exact same questions in mind. In fact, I'd typed a response to Sven's explanation, almost identical to your post. Edited it once I finally got the OP's idea...! My later post adds an extension, which involves a laptop/desktop, and negates the need for a Midi Mode 4-capable controller. This is further confusing, so let's ignore this laptop idea for the moment.

 

The following is the OP's idea (if I get it right! I'm taking the liberty here... :blush:):

You've hooked up your controller, on Midi Mode 4 (MM4), to the Alesis Andromeda. You hold down a chord with your left hand. MM4 ensures that the 3 notes of the chord are transmitted on channels 1, 2 and 3 respectively. Now you play a note with your right hand , it's on channel 4. Press down, aftertouch is transmitted - also on channel 4. But since the Andromeda is playing the chord in Chs. 1-3, the chord notes are not affected by aftertouch, which is on Ch. 4. Only the last played note, also on Ch. 4, is affected by afterouch. Presto, Pseudo-Poly AT. Hope I got it right, The Real MC...!

 

Pseudo-Poly AT differs from 'true' Poly AT in a crucial way. In the above example, with 'true' Poly AT, you could press down on the LH chord and the RH note differentially, at the same time - and the chord and the note would be proportionately affected by AT - to different degrees. OTOH, with Pseudo-Poly AT, pressing down on the LH chord affects only the last note struck! Channel AT averages all note-pressures, IIRC. Still, much more useful and interesting than having all notes affected by AT in the same way - which is the default behavior.

 

Now if you have a controller that doesn't have Midi Mode 4 - software to the rescue! The software mimics MM4 - every 'Note On' message triggers a channel change. Hook up a 1-in/1-out Midi interface, and it's exactly as if you have a MM4-enabled controller :). And not just the Andromeda, any keyboard/module/softsynth that meets conditions (a) and (b) in my previous post will work. Also, subsitute PB for AT in the above explanation, and it will work just the same way. Interesting, isn't it? A lot of folks here already have everything they need, to play around with (pseudo) Poly AT...!

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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I should have made it clear that the only part I didn't understand was your statement that the controller need not support MIDI mode 4.

 

I think you're wrong about MIDI Mode 4 being "pseudo". If it's implemented correctly, you should have true poly aftertouch: each key is on its own channel and should transmit aftertouch independently. Imagine having zones: shouldn't each zone have independent channel aftertouch? ("Should" and "it works" are unfortunately often not the same, though. Hardware might not support that.)

 

With your emulated mode 4 solution, the pseudo ply aftertouch is the best you can hope for. Is that very useful?

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Furthermore, you're incorrect about MIDI Mode 4 being "pseudo". If it's implemented correctly, you should have true poly aftertouch: each key is on its own channel and should transmit aftertouch independently.

As I understand, in case of Channel, the AT sensor strip internally averages pressure from all pressed keys, thus churning out only 1 single value at any point of time. I read somewhere that having each key transmit AT independent of others, requires a very expensive, radically different sensor technology. The price tag on a VAX77 (or the new Rhodes controller) bears this out :grin:. Given that everything else currently in production uses Channel AT, anything involving Midi Mode 4 has to be 'pseudo'- Poly AT. This is the current real-world scenario - I'm not sure what you mean by 'correct implementation'.

 

Imagine having zones: shouldn't each zone have independent channel aftertouch? ("Should" and "it works" are unfortunately often not the same, though.).
No clue as to how manufacturers implement multi-zone keyboards with AT. Each zone with it's own strip? Single AT for all zones? :idk:

 

With your emulated mode 4 solution, the pseudo ply aftertouch is the best you can hope for. Is that very useful?

It is exactly as useful - or not - as the OP's idea. As I pointed out, having the option of only the last note being affected by AT, is more useful than all notes being affected, whether you like it or not. Isn't that the very spirit behind synthesizers - to find more and more varied ways of sculpting sound, of expressing yourself musically...?

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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OK -- evidently channel aftertouch doesn't work with zones. Zone boundaries are configurable, so it would require the same hardware as poly.

 

I suspect The Real MC will be disappointed to learn that he can only control the last note played. It's not poly-aftertouch; it's "last note aftertouch".

 

Also, I bet that with either zones or mode 4, what you get with aftertouch will vary dramatically from product to product, since it falls between the cracks: none of them can do it correctly unless they have the hardware to support poly AT. You have assumed that they'll apply the aftertouch to the channel of the last note played. At least one keyboard sends it on the lowest channel. Who knows what the others might do?

 

Of course, your solution achieves the "last note aftertouch" feature regardless of how the controller is implemented, as long as it sends aftertouch on some channel.

 

PS: I didn't say whether I liked it or not. I just questioned the usefulness.

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You have assumed that they'll apply the aftertouch to the channel of the last note played.

The assumption is the OP's - not mine. I hadn't heard about Midi Mode 4 till I saw this thread... ;)!

Of course, your solution achieves the "last note aftertouch" feature regardless of how the controller is implemented, as long as it sends aftertouch on some channel.
:cool:

I suspect The Real MC will be disappointed to learn that he can only control the last note played.
:snax:
It's not poly-aftertouch; it's "last note aftertouch".

And thus, we are left with this burning question - is "last note aftertouch" more respectable - or less, than "pseudo-poly aftertouch"...? :grin: JK...

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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I should have clarified that you need a poly aftertouch sensor that doubles as mono aftertouch.

 

And I have heard from a couple of folks that the Prophet t8 has polyAT and can operate in MM4.

 

I put an mp3 sample of my experiment and the MIDI sequence, A6 patch (#118), and A6 mix (#127) in the folder below if anyone is interested in repeating it on their A6.

 

A6 PolyAT experiment files

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I should have clarified that you need a poly aftertouch sensor that doubles as mono aftertouch.

Lol! So now, the controller requirements are even more exclusive - Poly AT +MM4 capabilities. Do even the VAX77 and Rhodes qualify? :laugh:

 

Seriously, though - reading your original post gave me the impression that your idea involves last-note AT, and any Ch. AT/MM4-enabled controller. And that's not a bad idea at all. Consider this - all the variations that B3-er produces on his clip (on the VS forum), can easily be produced with last-note aftertouch. Also most of the variations on the clip you've posted. Again, with any AT-enabled controller. Sure, it's marginally less capable than a true-Poly AT. But considering that the alternative almost doesn't exist at all...

 

EDIT: With VAX77, a laptop, and the Andromeda (or any other keyboard/module/softsynth supporting per-layer channel input), you can have the holy grail - true Poly AT response. If the VAX77 is MM4 enabled, you don't need the laptop, either. Marzz might be able to test this out...

This is really what MIDI was originally about encouraging cooperation between companies that make the world a more creative place." - Dave Smith
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