Zam

Fader Automation

83 posts in this topic

Hi Eric

4k is my top estimation for my usecase

I'm around 2k only for fader and mechanic.

I don't believe it's possible under 3K for someone else (depending of some choices in design)

Of course I don't count the hundreds hours

Maybe with 100x 8 channel fader pack you can reach the 2K but this will never happen.

Best

Zam

 

 

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Hi all

Update and good new.

I just load a second fader assembly in the desk with cheap ALPS, the fader react way better with real pcb design (than with proto board).

No digital cross talk noise anymore !!!

Still way lower audio spec/tolerance, and louder wipper slide noise with the carbon track.

Also tend to oscillate but this is due to power supply setup (+/- 15 for the TKD)

So this can lower the bill around 750 buck compared to TKD,

Best

Zam

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That's great, I will be buying some for testing... I have a few other motion control ideas from the cnc world.. May have some off the shelf pid control boards with good clear DC. May be able to interface with Aout? anyway may be a cheaper alternative.

 

Eric

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Hi Eric

If you have control board in mind you can try, interfaced with Aout.

If you can wait few months, I will try to release my design.

I just find new problems with more than on fader connected...back to the lab :)

Best

Zam

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Thanks Zam!!

My neotek board is arriving this weekend and I will have plenty of things to do for some time before I will be starting this project, I just find it so so interesting I cant stop reading about this:)

It combines motion control and audio... both very interesting. On a side note I have a very good friend who is a senior software engineer at Microsoft and I had a discussion with him regarding MTC and interfacing it through software and oddly enough he actually already wrote a piece of software for that exact reason. More for me to think about. 

Eric

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Thanks Zam!!

My neotek board is arriving this weekend and I will have plenty of things to do for some time before I will be starting this project, I just find it so so interesting I cant stop reading about this:)

It combines motion control and audio... both very interesting. On a side note I have a very good friend who is a senior software engineer at Microsoft and I had a discussion with him regarding MTC and interfacing it through software and oddly enough he actually already wrote a piece of software for that exact reason. More for me to think about. 

Eric

Hi Eric

MTC is one thing, if you go that route you also have to include a system that store/rec/read ALL fader data position (according to time code) which is another thing...

I don't see the need for this with DAW today, I understand it for the time you have to sync tape multitrack, but today ?

I'm interested to see the point/usecase to go this route.

Best

Zam

 

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Zam,

 

Your most likley correct, but what I found interesting is that the MTC idea is not dependent on the DAW as well as a modern 32 bit motion control would allow for a much smoother more detailed motion. In terms of the software side I think the rec playback would be pretty straight forward but the error correction PID feedback may be a bit more challenging.As well as an intelligent GUI etc..More just thinking out loud really, your approach is most likely the best :)

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Hi

Maybe I'm wrong but is't the DAW automation internally  sinc'ed with MTC ? anyway MTC is 120 tick per sec at best (30f/s with quarter)

So using DAW is in a way the same as embedded MTC, just without all this code to write

Full range respond is 100ms for my system so the 10ms lag is negligible to me, and no need to be better. I don't plan tu use the fader as fast compressor :)

Regarding precision, I feel 10bit is way enough, it's 0.1mm steps !!!

The re-recording test show me that two pass reading the same automation with the same audio result in a phase cancellation that i'm not able to cancel better with +/-0.01 dB trim, at static step of course. I was myself very impressed whit this result (pcb version, protoboard was not as good)

For smooth and detail you have to see the fader with 30min ramp, you just don't believe it's moving, you come 5 minutes after and the fader had moved 1cm:happy:

For me the PID has nothing to do with the automation data, comparator is at analogue side, whatever data you print/sendback. What kind of error you have in mind? I'm not sure to understand what you mean.

Best

zam

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Pretty sure your approach is the best.. All of the Automation heavy lifting has been done by the Daw software. How is your progress coming along? My new board is fully installed and working great! plenty of room for adding multiple boards if needed. 

Eric

 

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Hi Eric

I'm little stuck to fund a full 8 fader pack right now...(I have a desk for sell if interested :cencored:)

I have two TKD fader loaded and it work great, I still have one issue, I reduce the problem a lot, I have to decide if I can keep it this way

I made few little mistake in the layout that require a rev 2 board for motor driver and I/O board. Main error was a buffer amp wired as inverter in place of non inverting, and some footprint error like wima filter capacitor with 2.5 in place of 5mm. I just cut trace and rework PCB for now, anyway, it need correction at KiCad schem and layout for a realease

 

The real issue I just talk about, is voltage drop at the 5v rail with all led ON, I also use it for servo without local regulation.

It just corrupt the AD side stability of the system, by changing the reference voltage, introducing comparator error and fader move.

Initial layout put this error in the mm range, completely unacceptable.

I was able to reduce this in non perceptible range by // 5Vtrace with 0.25mm2 wire and connect the SMPS sens at I/O board (prevously 3m away at the 19" rack with the core).

Now I'm in the 10mV drop range which still enough to introduce jitter at 12Bit AD and of course error at analogue comparator.

As I say it's non perceptible, at worst 2 step<=>0.2mm (7 led ON), and this "jitter" will always be the same.

I mean for example in read mode the green LED will always light on, introducing exactly the same error for each pass, without relative difference. The worst is with mute function which light a red LED and an optocoupler, but If I mute I don't care the fader move 1/10mm

So here it is:

Do I keep it like this, not so smart design, with my subjective knowledge saying "it's not the best possible", when objective observation show it's just out of human perception.

Or do I push a little more further and add local regulation, which will implies deeper modification.

 

I still have 5V layout modification to made, not easy to change the "basic" when all complexity around is done, maybe I have to go for 4layer pcb! I don't see to just add 5V wire jumpers a very professional design.

There is few option and I have to make the right choices to avoid V3 to soon...

 

Last important thing for the system is the the data mapping at soft side, also OSC, but that's another topic.

 

I have few call at groupDIY, I wish I can release this.

For info, I/O board is 250x85mm, not more than 30cm cable/ribbon from the fader/motor board.

Motor board is 34x120mm as close as possible to the fader,

and remote is 16x150mm as close as possible to the front panel :)

 

Best

Zam

 

 

 

 

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Zam,

Thats an interesting issue.. Can you add another 5 volt rail? and just keep the regulation at the power supply? Not sure if that would keep the layout at the fader side less complicated? But I sense you are a perfectionist :). Maybe just leaving it as is will be fine!  And thanks for the measurements they will fit with no issues! 

http://lifehacker.com/the-30-percent-rule-and-the-art-of-early-feedback-1619474527

 

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hey

No, I can't add another 5V rail just for servo, AD and DA chips reference will not be the same, or won't "move" the same.

For now I think something like a 5V "star" layout will be the best compromise, But the I/O board is just busy as hell, I design a 2 side PCB with ground plane for 64D I/O and 8 A I/O. and the ground plane is clean as hell !!! so just imagine the bottom side

yes that's my default... i'm a perfectionist...

your link is instructive... I just miss the 30% one years ago...:decayed:

best

Zam

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HA,

I am glad liked the link... I often remind myself while mixing my own music. I will be ready once you decide for some beta testing. I can help defer some cost for you as well group buying faders and PCB :)

Eric

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Yes I know you can help :)

Let see how groupDIY community react, i just ask for "interest" to see the potential of this project. there is so many things to coordinate if a release is made. Including bridge with community here at midibox

best

Zam

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Zam, 

You may want to do a feeler thread over on GroupDIY.. The traffic on the mixer thread is small.. Also you may only have a small handful of folks interested like myself!! On another completely different note. I was looking at ways to do a faster D/A conversion or filtering on a PWM signal and I found an interesting chip that will take a PWM stream and convert it to smooth DC in 8us Linear Technologys LTC2645 . Not sure if it would simplify the design? I know your way past that stage of your design was just really thinking out loud! 


Eric

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Hi Eric

I start a new thread at GDY

I don't see this chips when I look to smooth PWM 1 years ago.

Yes maybe it would simplifies the design, with less component. Still need to have "power" output to drive a 10 or 12 V motor at 200 to 500mA ! buffer and push-pull ?

Also the PID have to be at soft side then, I'm not a programming guy (that's why I'm here :happy:).

Finally I don't find MSOP pakage so diy friendly with 0.5mm footprint.

It could be an interesting other route, if someone like to try it with actual MF_NG.

But what I see then, if you already have PID at soft side, just use a DA with powered output...no PWM

 

Best

Zam

 

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Zam,

Like I said just thinking about ways to simplify things.. You have worked so hard on your design its most likely the best option!

I will make sure and comment on your GroupDiy thread!

Eric

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Zam, 

Why dont you use the MF_NG? I was planning on getting some TKD faders and use a MF_NG module. Is there any problem with it? 

Thanks!

Edited by tomas1808

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Hello

I don't test the MF_NG with TKD, only with ALPS and it was to noisy with them, with PWM leaking to audio.

Best

Zam

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wow, nice performance!

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Thanks Novski !

Yes it become better and better.

Hope I can share a rock solid system soon.

Best

Zam

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Hi all

 

First batch on the way :happy:

Around 10 pcb set will be available soon (I order 15 but I need some and 1 is reserved for TK)

Best

Zam

Edited by Zam

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save me one of them. :grin:

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1 hour ago, novski said:

save me one of them. :grin:

Hello Novski

Ok, you are on the list ;)

I will update in 2 or 3 week with price and technical info/notes

Best

Zam

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