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High precision pitch fader?


Guest Xspringe
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Guest Xspringe

Hello everyone,

For a while I've been looking for a decent way to control the pitch in Traktor (http://www.native-instruments.com/index.php?traktor_us) using a MIDI controller, preferrably using a 100mm fader.

The main problem I have encountered is that all the MIDI controllers available right now that I am aware are limited to 7 bits precision for the fader. This results in a precision of 0,16 % for a pitch range of 20% (+/- 10%) which is simply not acceptable for professional DJing.

The minimum precision required is probably closer to 12 bit, and preferrably at 14 bit.

I would like to know if anyone knows if any currently available MIDI controllers have faders with 12/14 bit precision. And if this is not the case, how difficult it would be to build such a thing/have it built.

Thanks in advance!

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Guest Xspringe
The problem is probably not the fader but the midi protocol. Few midi commands support 14 bit encoding, pitch bend is one.

Thanks for the info. Could the pitch bend command be used to indicate the pitch?

edit: let me elaborate. Do you think it would be possible to have the pitch slider send out positional information as MIDI pitch bend commands and then have the software (on the computer) interpret it as if it were pitch information?

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  • 2 weeks later...
Guest nomadicWhale

Hi,

The problem is that the pic18 supports only 10bit resultion. this means that no matter what faders you have and no matter what protocol you use, the pic18 will not be able to produce more that 10bit resulotion readings from your faders, and thus, will not be able to send finer than 10bit events.

One option you might consider is using 2 faders - one for the rough tuning and the other for the fine tuning. I'm not sure how comfotable it will be, but I think it is worth the try. It just requires some easy mios programming.

Another option might be (and I'm not sure about this, I might be talking crazy here) to have some sort of hardware change in which one fader is connected to 2 ain pins while divding the voltage between them. this is just an idea comming from someone who does not really knows electronics. just a thought.

nW

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Is it right, that 10bit gives 1024 steps? If so, this would equal to 0.098mm per step on a 100mm fader. I think a higher resolution for 100mm wouldn't be reasonably precise controllable anymore.

Why not implement a "shift" button, which is programmed to change the fader-dedication from "pitch" to "finetune"?

Greets, Roger

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Guest Xspringe
Hi,

The problem is that the pic18 supports only 10bit resultion. this means that no matter what faders you have and no matter what protocol you use, the pic18 will not be able to produce more that 10bit resulotion readings from your faders, and thus, will not be able to send finer than 10bit events.

One option you might consider is using 2 faders - one for the rough tuning and the other for the fine tuning. I'm not sure how comfotable it will be, but I think it is worth the try. It just requires some easy mios programming.

Another option might be (and I'm not sure about this, I might be talking crazy here) to have some sort of hardware change in which one fader is connected to 2 ain pins while divding the voltage between them. this is just an idea comming from someone who does not really knows electronics. just a thought.

nW

Is the pic18 a chip converting the analogue fader info into digital readings?

The two fader system isnt really an option due to the mechanics of DJing, thanks for the suggestion though!

Indeed, a possible option might be to use two 10bit (if this really is the maximum achievable) encoders for per fader, each for 5cm of the fader. Fact is that using an 11 bit encoder instead of two 10 bit encoders gives a much larger gain in precision and is probably easier to build (because it's less complex).

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Guest Xspringe
Is it right, that 10bit gives 1024 steps? If so, this would equal to 0.098mm per step on a 100mm fader. I think a higher resolution for 100mm wouldn't be reasonably precise controllable anymore.

Why not implement a "shift" button, which is programmed to change the fader-dedication from "pitch" to "finetune"?

Greets, Roger

Thanks for your reply Roger.

It's really difficult to judge exactly how much precision one needs. From personal experience using a digital mixing program with a pitch precision of 0.01% (Traktor Studio) I can tell that this is not enough for professional mixing (mixes continue to drift more often then using regular turntables).

Having a 100mm fader indicate a value of between -10 and +10 % with a resolution of 1024 steps leads to a precision of approx 0.01%, which from my personal experience isn't good enough.

Then again, I might be totally wrong. But this is the only empirical data I have for estimating the required minimal precision (and the data is, I must admit, pretty subjective).

Thanks everyone for your input so far!

I'm still curious though if the pitch bend command could be used to indicate the pitch by having the computer software reinterpret it.

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Hi Xspringe

It's pretty hard for me to explain exactly what I mean in english.

I'll try it with different words...

I mean you only have 100mm phsical way with the fader. So if you got 1024 steps I think when your finger is shaking a bit, you'll propably already skip more than one step.

Greets, Roger

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Guest Xspringe
Hi Xspringe

It's pretty hard for me to explain exactly what I mean in english.

I'll try it with different words...

I mean you only have 100mm phsical way with the fader. So if you got 1024 steps I think when your finger is shaking a bit, you'll propably already skip more than one step.

Greets, Roger

Yeah I understand that. But I can assure you that moving the fader around can happen in quite small increments.

The main problem arises when for synchronizing two songsyou require a value which is somewhere in between of say 4.56 and 4.57%, because in that instance you simply will not be able to perfectly synchronize both songs.

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