TK.

Upcoming MBHP_MF_NG module

387 posts in this topic

Just as I was giving up hope, I got it to work.  I spent all last night reading every post I could find and in one post in another thread @Zam talks about the fader plate being to thin for grounding or something along those lines. Anyways, as I was ready to pack it all up and thought let me try one more thing. Everything I tried was grounding to the case which is about 1mm thick but every time I grounded anything to the chassis, nothing got better. So I thought let me try something thicker, as soon as I grounded it to the rack rails of my desk (rack rails are 3mm thick) ...Voila! the noise was gone. @Zam was right all along. 

On 6/23/2020 at 7:32 AM, Zam said:

You'll have to try to chassis ground fader metal part to minimize EMI leaking and motor sparkle.

As soon as I grounded the J14, the fader metal and the motor case everything was noise free. It was the temporary case I was using that wasn't sufficient to be used as a ground.

@Zamgave me the best advise (and I didn't listen) which was:

On 6/23/2020 at 0:50 PM, Zam said:

As a global rules, as it is for console integration, I'll suggest to build the thing as close as possible to final integration, to minimise bad surprise at the end as loosing time to fix issue that will not happen in the proper frame/mechanical integration.

So now I'm off to design my face plate and get it either in 3mm aluminum anodized or aluminium powder-coated. If anyone knows if there is going to an issue with either of these materials and grounding please let me know.

Thanks again @Zam for the help!

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Hello Zeke

Good you find solutions to your problem

It seem (I can be wrong) that you misunderstood  the concept of ground, the thickness of a case have noting to do with it, I suspect in your fist attempt you just connect together your Vref (0V here), fader can and metal case, without path to safety/earth ground, meaning everything stay floating. As soon as you connect all this to rack frame you create a path via rail and other equipments, I suggest your fader rack get it's own path to main ground to not interfere with other equipment (otherwise parasitic current might flow trough them)

technical note: powder coating as anodization (surface only) are non conductive !

for example you have to mask before coating or scratch surface after, if you want proper conduction between metal part in rack assembly.

Best

Zam

 

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@Zam Feels good to solve a problem, that's for sure. Especially since I am very new to all this. You are right though, I may have confused the concept of grounding. As an experiment, I will try later today to scratch the case I have because it might be the coating that was causing it not to ground properly. I'm using Front panel designer and the materials that I can use for making the face plate aluminum anodized or aluminium powder-coated. What if I used Aluminum Raw is that conductive enough?

I'm going to do more research on earth/ground but my understanding is grounding is done by going to a chassis and earth is going to..... well earth. My limited understanding is the way you earth is via the power receptacle but this board only has 2 holes, a negative and a positive. So I'll have to figure out how to earth it.

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Use the material you want for the visual finish you want ! row alu is ugly for front panel and easy to scratch...

I'm just saying this in the manner that you should anticipate your enclosure design and be sure all metal part have good electrical connection between them, a recessed screw or countersunk head screw that fix front panel to frame should be enough (as milling will remove the surface anodization )

"basically" your pcb 0V should be hooked at one (and only one) solid screw at the frame (common ground), preferably close to the main entry, where you also connect the safety earth ground from the (close) main connector.

In your particular usecase I think fader screw mount (countersunk) will do the job to connect fader metal can to common ground.

Your fader 0V audio should not share the fader box common ground, it's already connected at console rack module via trace, pcb and local chassis common ground.

Try to imagine the audio part of the fader as an isolated extension from outside the fader box.

Best
Zam

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Hi!

I'm having troubles setting up MF_NG.

Everything seems to work fine, i was able to get faders moving and all, but there's a big rattle noise when faders are moving slowly (ie using the MIOS studio tool to make them move slowly, or following the daw automation).

this rattling noise disapear when faders are moving fast.

I tried to play with the different parameters, but i couldn't find a way to make that noise disapear.

Currently i'm using ALPS K faders. but i got the same issue with an old P&G i had lying around. I tried 8 faders and had the issue with all of them.

I'm pretty sure i'm doing something wrong here, but i can't figure out what...

 

Thank for your help!

 

Thomas

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Hello

 

On 20/08/2020 at 0:11 PM, totoRaymond said:

I'm pretty sure i'm doing something wrong here, but i can't figure out what...

 

I'm not sure you do wrong, this is probably intrinsically related to PWM driver

Best

Zam

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Hi Zam,

 

After reading ths whole topic again last week-end, I tried to lower the voltage.

With Vm down to about 4V, i was able to get rid of most of the mechanical noise, but now the faders are a bit sluggish (actually, there's only one fader wired to the board right now).

 

The PWM might be the problem, I know you went another route for your analog automation system (I followed the story since the beginning on gdyi). Do you think we could get rid of that noise using a higher PWM frequency? Or is it necessary to drive faders with DACs instead?

There must be a way to drive faders in silence, I work all day on digidesign D-Command, they use the same ALPS K-faders I have and they're very quiet (and fast).

I think i could live with slow faders for a time, but I might try to move to another solution once my controller is finally assembled.

 

Cheers,

 

Thomas

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Hey Thomas

As you notice I take another route long time ago, I'm not able to help you much about PWM handling

I think I publish all my tries around PWM by that time, and there is probably other options to test today, including increasing frequency of the PWM (over audio range). IIRC mios8 on the pic can't do this ?

Do you know how is handled the motor in the D-com ?

Best

Zam

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No worrys, as I said, i think i will settle for this solution for now.

I'd like to have a working build before end of the year and improve from there.

If I remember well, you're problem with PWM was related to EMI leaking into the analog circuitry, not the actual physical noise of the fader. Am I right?

You're right, the PIC used on MF_NG won't go higher in frequency, But if need be, i'm not afraid to port the code to a more capable micro... (as long as i have a working controller, i have all the time in the world to make it better... :angelnot:)

I never looked inside a D-command, but if i get a chance, i'll check the Ic's used (might even look inside an Avid S6, who knows, those faders are great). I'm going to start looking into some other controllers too.

Thanks!

 

Thomas

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17 hours ago, totoRaymond said:

If I remember well, you're problem with PWM was related to EMI leaking into the analog circuitry, not the actual physical noise of the fader. Am I right?

It was both,

EMI not acceptable regarding technical performance I requested then, with that particularity that I have low level audio signal just across the digital circuit, which is not a question/issue for 99% of pple using MF_NG.

As acoustic noise that can't match the quality standard at user side I was searching for, in a quiet as possible "high-end" control room I can't work with a bunch of printer like sound, unfortunately a fader automation is not a tool that you can put in the machine room :rolleyes:

In a way both noises are linked.

Best

Zam

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I haven't posted in a while but I did get mine working after all. I'm using mine for automation of my channel strips, I record the levels into my DAW and it recalls with every session. so I don't really need any other buttons. My whole desk is custom so unfortunately, it's not in my desk at the moment because I would have to make a new desk, which will happen next year. So it's just sitting behind my desk out of sight. I end up controlling both fader banks with my avid artist mix or through the DAW. I will try and make a video so you can see it working.

@totoRaymond are you trying to build a DAW controller or an automation system for a mixing console? Do you have all 8 faders attached to the module? I found that once you have all 8 faders populated, wired and grounded properly that if you power the modules at 7v this reduced the noise. There are some settings also that may help. I'll try to find them.

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HI Zeke and thanks for the advice!

I'm building a DAW controller, basically i'll emulate 3 Mackie Control Units plus a "generic remote" to control Nuendo. In the end, i hope to get 25 faders plus a bunch of stuff (including a touch screen with a lemur patch). I reported my progress in this thread (not updated very often though) :

Right now i have only fader attached to the board. The wiring with this board is a bit of a mess so i'm currently making a new pcb with one connector for each fader to keep things tidy.

I'll definitely try with 8 faders connected, but in the near future i have to build a prototype enclosure (made of MDF i have lying around) so i can start to assemble everything properly (and stop killing board with shorted wires).

All the fine tuning will be done once I gathered all the parts.

 

Cheers,

Thomas

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