Yamaha FC7 in conjunction with MIDI Expression

[Miqaellux]

Hi,
I am considering purchasing of MIDI Expression for cooperation with Yamaha FC7, but I've read Fc7 has not linear action directly after plug in to MIDI Expression and most other interfaces. However I'd like to reach full range of midi values, which will be controlled by this pedal directly proportionaly to its position - when the pedal is in 0% of action (full range of its motion) I'd like the pedal to send 0 midi value, in 25% - 32, in 50% - 64... up to 100% - 127. Is it now possible without any additional adapters and any interference in Expression curve? I ask, because You wrote on that topic about this issue with FC7: "I'll do some more testing, but I suspect there's also a resistor built into that adapter [FC7X-II] that changes the taper of the pot.[...] I suspect I can conjure up a firmware solution to the issue as well. Thanks for bringing this to my attention." If not, is it certain that Yamaha FC7 with that adapter (FC7X-II) in conjunction with MIDI Expression will send full range of midi values adequate to its real position?
Thanks in advance for your answer.

[Rob]

I am considering purchasing of MIDI Expression for cooperation with Yamaha FC7, but I've read Fc7 has not linear action directly after plug in to MIDI Expression and most other interfaces

That is correct, it has a 50K Log pot inside it. It responds like a volume pedal as opposed to an expression pedal.

However I'd like to reach full range of midi values, which will be controlled by this pedal directly proportionaly to its position - when the pedal is in 0% of action (full range of its motion) I'd like the pedal to send 0 midi value, in 25% - 32, in 50% - 64... up to 100% - 127. Is it now possible without any additional adapters and any interference in Expression curve?

With the Expression Curve, it is possible to get something close to linear, but it won't be perfect. You will however be able to get it to track the full range of values from 0 -127. I've included a screenshot. The biggest issue facing this pedal is not so much that it has a log response, but that the pot is 50K. MIDI Expression is optimized for 10K pots, and the difference in impedance causes that pedal to be a bit noisy. The smoothing function takes care of most of the noise, but at the expense of responsiveness when moving the pedal very slowly (I'll try to make a video for you this weekend).

Untitled.png (43.49 KiB) Viewed 3076 times

If not, is it certain that Yamaha FC7 with that adapter (FC7X-II) in conjunction with MIDI Expression will send full range of midi values adequate to its real position?

I have no idea, but from what I've read from their website, I don't think so. I'll make my own and see if it improves the situation at all.
Regards,
Rob

[Miqaellux]

Thank you Rob for your answer and willingnes to resolve this issue. I realize that FC7 is problematic, but also exceptional from other side. I'm going to use this pedal because of its unusual pretty big throw (angle of motion), whereby one can reach much better control, relative to unproblematic pedals like EV-5, EX-P, but obviously only with linear responsiveness. Many people highly appreciate FC7 and recommend it widely, but maybe you can recommend me other expression pedal with as so big throw as FC7, nice feeling and solid construction?
I was glad when I read keyguy's post on the forum:

Rob, I solved my problem. I bought a FC7X-II from Ashby Solutions. It reverses the polarity. Now it works perfectly! I have the full range of the pedal without having to change the expression curve at all.

and I thought the issue with FC7 had been solved.
Are you sure that FC7X-II only reverses the polarity without any additional resistor? Perhaps switching the polarity isn't the only function in this adapter. It would be good to know how in fact this adapter works. I'd like to be sure that keyguy's combination will be working just as I wish.
Last question, maybe you can conjure up any mod to Yamaha FC7, so that this pedal becomes finally compatibile to interfaces other then Yamaha's?
Regards,
Michal

[Rob]

I just bought that adapter. It'll probably take a week or two to get here, but I'll let you know how it works when I get a chance to test it.

Regards,
Rob

[Rob]

Just got it today. Works perfectly. Straight linear response. Anyone else looking for this adapter can get one by following the link below.

http://music.ashbysolutions.com/misc.htm

[Miqaellux]

Splendidly - Rob, thank you so much for your helpfulness. I'm purchasing your interface and this adapter soon.
Btw. Do you know now how this adapter works? Does it really switch only polarity?

[Rob]

I can confirm that it is only switching the polarity.

[Rob]

Upon investigating this adapter, I found a way to modify the design of MIDI Expression devices to properly support this pedal and several others without the use of the adapter.

See this thread for details.
http://www.audiofront.net/forum/viewtop ... f=26&t=229