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Yamaha KX88 Aftertouch Help


BadDog1123
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I have a vintage Yamaha KX88 controller that is not sending "channel pressure" messages over MIDI. The KX88 supports both polyphonic key and channel pressure aftertouch. I have two other modern Studiologic MIDI controllers that also support aftertouch and do send channel pressure messages as I press harder on the keys. Does anyone know how to program the KX88 to send the equivalent of channel pressure with aftertouch?
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Thanks, timwat. I found this FAQ previously when I Googled "KX88 aftertouch MIDI", but after reading the article it is still unclear to me how I configure the KX88 aftertouch control to send key or channel pressure messages, which do not appear to have a traditional MIDI CC value associated.
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Hi-

 

Take a look at page 14 of the user manual. You"ll need to enter CA (controller assign) mode. Once there you"ll be selecting the controller you want to assign - in this case the After Touch Controller. Then you need to actually assign a function to it which is shown in the table on page 24. Select '13" for after touch. I know, it sounds silly assigning after touch to the aftertouch controller but you could have your aftertouch controller transmit any number of other midi controller messages as shown in the table.

 

Once you have the aftertouch controller transmitting aftertouch make sure your Sledge is set up to receive aftertouch on the same midi channel as that of the KX88. And remember you have 2 channels on the KX88 so make sure you"ve configured the aftertouch for the desired channel.

 

Btw the KX88 only transmits channel after touch, not Poly after touch.

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Btw the KX88 only transmits channel after touch, not Poly after touch.

The ever-popular Midi Implementation Chart. The 1st product manual page I look at for any synth I ever bought. :)

Gear:

Hardware: Kurzweil Forte7, Korg Kronos 2, Novation Summit

Software: Cantabile 3, Halion Sonic 3 and assorted VST plug-ins.

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Take a look at page 14 of the user manual. You"ll need to enter CA (controller assign) mode. Once there you"ll be selecting the controller you want to assign - in this case the After Touch Controller. Then you need to actually assign a function to it which is shown in the table on page 24. Select '13" for after touch. I know, it sounds silly assigning after touch to the aftertouch controller but you could have your aftertouch controller transmit any number of other midi controller messages as shown in the table.

 

Thank you, Markyboard!! It doesn't seem logical that one would need to assign aftertouch to aftertouch, but that it would just work that way out-of-the-box. I will indeed try your suggestion and report back for the benefit of other KX88 owners that may have struggled with the same issue.

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Markyboard's suggestion did the trick! I am now sending channel pressure messages to my host. So my only other question is, can the pressure sensitivity be adjusted on the KX88? I've read (and now experienced first-hand) just how hard you have to press to increase the channel pressure value, or to register any channel pressure at all really. Is there some adjustment to make the KX88 respond to aftertouch without pressing down so hard?
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Hey cool! I didn't see any internal parameter like an aftertouch curve or sensitivity setting in the user manual when I looked a few days ago. Roland typically has a potentiometer on one of the circuit boards to adjust the amount of current used by the AT although this didn't do much if anything on the A80 of the same era. I imagine Yamaha boards could have something similar. Here is the service manual but unfortunately no schematic. You might try contacting Yamaha service. They were always excellent back in the day when I had Yamaha synths.
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I have a service manual with schematics. Here's a link to it in my Dropbox, I'll leave it there for a while: https://www.dropbox.com/s/r95xea32vv26aur/KX88YAMAHAServiceManual-EN.pdf

 

I checked it out and BadDog it looks like you may be in luck â but only if I'm lucky in correctly identifying what looks to me like the AT adjust trim pot. You're reading the words of a Heathkit-level electronics "enthusiast." :) I do hope I'm correct â so as not to feel bad if you spend a few hours disassembling this beast!

 

I found this on page 22:

 

KX88-AT.jpg

 

And this on page 7:

 

KX88-AT-VR1.jpg

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Hey cool Rob- my version was missing page 7and 8. I believe you actually want to adjust VR2. VR1 is used to adjust the reference voltage so that with no aftertouch applied you get 0 Volts out. Probably best not to mess with this as long as there"s no aftertouch when you"re not pressing down on the pressure sensor.
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Ha! I didn't even notice VR2 on the schematic and figured it was an adjustment for something else on the circuit board. Of course the board is labeled with "zero" and "gain", that should have been a clue â not for me I guess!

 

As far as whether it's worth trying to mess with VR2 - I only know that a small trimpot in my Roland controller turned my channel AT from needing Superman-like force to squeeze a few data bytes out of it, to completely usable. Of course that may mean nothing as we're talking two competing manufacturers with products separated by over 20 years.

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  • 2 weeks later...

Update...

 

So I bravely opened my KX88 and adjusted the VR1 and VR2 values to eke out a bit more pressure responsiveness. You can access both trimpots without removing the mainboard by using a small jeweler's (straight) screwdriver. The best setting for me was with both VR1 and VR2 clockwise all the way. I still have to apply more pressure than with my Studiologic SL88, but it's better than it was and I can now generate channel pressure all the way up to a value of 127 which I could not previously.

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Great to hear of your success. I've rarely been afraid to pop the hood on a piece of my gear (after it's out of warranty of course)! Though I hardly ever use it, I don't think I'll ever part with my KX88. I like its feel, and it has a solidity unlike anything made today that I've encountered. Of course I won't be carrying it to gigs either! Not to mention what I paid for it:

 

kx88.jpg

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