automation: the 89MotioN system

[audiomixer]

I was referring to the service manual, p115 ov the 990 series....

no pwm, more like anaolg PID type regulation.

- Michael

 

[zamproject]

i download it in the mean time

Ufader come directly from the fader
USOLL come from the processor board. analog mux/demux --> flip/flop--> intel MCU

i will have a look at PID

Zam

 

[Andy Peters]

Not to derail your thread but an idea I had was to tap the voltage on a standard moving fader (non audio as used in something like the Mackie Control or Avid Artist) and scale the voltage and filter before using it to control a VCA.

The faders on the Mackie Control drive encoder wheels, they are not potentiometers.

-a

 

[zamproject]

I was referring to the service manual, p115 ov the 990 series....

no pwm, more like anaolg PID type regulation.

- Michael

I just have a study time of this circuit.

for what I understand Usoll should be the data comming from contrôle systeme (PWM?)
-there is two LP filter in series and IC4 look like an active low pass (i don't understand R4?)
-then this signal is mixed with fader wiper DC data and go to IC2
-IC2 look also like a active low pass, but i don't understand the zener, is that just a voltage limiter ?
-two IC and 4 transistor as H bridge to drive the motor

maybe I can test this schematic on my board to replace the actual L293D
if I well understand, this schem provide a smooth DC output, and will remove PWM leaking on analogue audio side

advise welcome

best
Zam

 

[thismanysounds]

Hi Zam,

I have been following your progress over on the Midibox forum. It seems like you have had some success in improving the electrical noise. Was this a software fix or a result of smoothing the PWM output?

If this turns out to be usable I see a DIY mixer in my future!

 

[zamproject]

hi manysound

I have a follower ! 

As this systeme is complex (for me) and involve multiple technologies, i just can say the actual improvement is a mix of all.
-electric side, PWM smooth with 100u acros the motor (2x220uF as non polarized electrolithic)
-Soft side by changing the shift register pulse frequency (for touch sensor) to inaudible intermodulation from 1K to 30Hz. But I still ear the 10us pulse, tks to my PSI monitor !!!
-mechanic/frame side with new 3mm front panel proto
-shielded and separate cable in place of the initial flat ribon

BUT i'm not happy with that for the moment, I think one of the problem is the fader design himself, I don't open one to see the track, but I suspect regarding the size of this ALPS that the 3 track are too close form each other. I need to order some TKD, P&G, or upper class RSA0K ALPS

As I never put my hands on hiend passive flying/motor/fader/shadow system, I have no ideas if spec i have now are good or bad

noise (for one fader) is around my Studer noise floor(which is not so low...) and the position accuracy is about +/-1dB
Since I add the caps to the motor, systeme seems to undershoot the target, without repositioning.
but as it undershoot always the same, I have interesting result with phase cancellation when comparing two mixdown (one channel mono track)
So I better say accuracy is +/-1dB between the automation rec and automation read
If i read (and compare) two time the same rec, I'm around +/-0.2db in static time (that's the trim compensation I have to adjust to nul phase at best around -60dB), moving time is way worst !!! it's difficult to calculate...but fade-in with deviation to initial curve, even few dB somewhere in the travel if you go from cut to unity, don't sound bad to me.

Zam

 

[zamproject]

some update

have some accuracy test today with new setup configuration
accuracy between automation rec and automation play is lowered at +/- 0.4dB max, less than 1dB
accuracy between 2 automation play (audio recorded two time trough automated fader) is +/- 0.05 dB, 1/10dB
I was able to track and target the max 10bit resolution, 1024 step in the 10cm fader --> 1mm
I think i can't do better...

next step:
-pitchbend code table (to compile for the PIC) to match DAW fader log value and real fader attenuation, so fader group will keep relative gain at the analog side
-order better fader, hope lower the noise  :-X

new idea to add:
some 2 position switch that select automated fader resistive track OR a simple resistor lader that give me unity gain at the channel.
With this fader stay active and I keep automation at DAW side only, as a remote.

Zam

 

[ruairioflaherty]

Not to derail your thread but an idea I had was to tap the voltage on a standard moving fader (non audio as used in something like the Mackie Control or Avid Artist) and scale the voltage and filter before using it to control a VCA.

The faders on the Mackie Control drive encoder wheels, they are not potentiometers.

-a

Sorry Andy, missed this, thanks.

You've touched on an area I know almost nothing about.  What exactly is being varied by the fader? Or perhaps better asked what is the encoder wheel measuring?

 

[zamproject]

Or perhaps better asked what is the encoder wheel measuring?

an angle and number of turn i think

 

[Andy Peters]

The faders on the Mackie Control drive encoder wheels, they are not potentiometers.

Sorry Andy, missed this, thanks.

You've touched on an area I know almost nothing about.  What exactly is being varied by the fader? Or perhaps better asked what is the encoder wheel measuring?

They encode position.

When the thing starts up, it calibrates the faders by driving them all to the tops of their travels, and then reversing and driving them back to the bottoms of their travels. While I don't know exactly what's going on in their firmware, my guess is that they do this to get a 0 reference count at the top of travel and as the faders are driven to the bottom of travel, they count the number of blips on the encoder wheel, and simple math indicates where you are in the travel.

As the human moves the fader, the new position is sent to the DAW over MIDI. Or as automation is read by the DAW as a song plays, the new position is sent to the controller, which drives the motor to move the fader to meet the new position. It does work well.

I don't know if they detect stall on the motor to know when each is at the end of travel, or if there are separate limit switches for that. I haven't had it apart in ages.

 

[ruairioflaherty]

Great info, thanks Andy.

I have a Mackie Control and a Mackie Control mini at home, not really using either anymore.

 

[thismanysounds]

Hi Zam,

Thanks for replying. You have a really interesting project on your hands. What motorfaders are you using at the moment?

some 2 position switch that select automated fader resistive track OR a simple resistor lader that give me unity gain at the channel.

This is exactly what I was thinking. Start the mix with a summing mixer and automation ITB, then do stem tweaks with real faders.

Looking forward to your next instalment!

 

[zamproject]

Hi Zam,

Thanks for replying. You have a really interesting project on your hands. What motorfaders are you using at the moment?

some 2 position switch that select automated fader resistive track OR a simple resistor lader that give me unity gain at the channel.

This is exactly what I was thinking. Start the mix with a summing mixer and automation ITB, then do stem tweaks with real faders.

Looking forward to your next instalment!

hey

I use ALPS RSA0 series, I have contact with TKD suplier but I wait a little to order ($$$) as I'm not happy with the drive system at the moment
I have a serious look with a friend (way stronger than me in electronic!!!) to the 990 fader driver, i'm wrong about it. It's not an H bridge but a full analog motor driver, pure variable DC ... no noise at all
I'm on the way to prototype this (or find spare card) and adapt them at the PIC I/O

Also TK just wrote a new firmware for the need (I have) to adjust the 10bits scaling between DAW fader and real fader.
amazing !!!
I have to beta test this one before TK release it, I have a quick test this evening, seem to work fine, fader grouping will work !!!
I just can't perform a full test, I'm in the middle of mix session and can't load my two proto motor fader in the desk frame

-----

About the "unity" switch, I think it's a nice and easy feature to add, but I have to admit 90% of my comp are at the anolog side.
My desk sound better if I keep line in at nominal level, also a noise floor and gain structure optimisation.
So I will not use this all the time.

best

Zam

 

[zamproject]

hey all
here some report, just a quote from my post in the midibox forum regarding the new table tool
fader group and gain structure is a success 

I made a 42 point table !!!, 1dB step from 0 (top) to -30 and 5dB from 30 to cut (bottom). the 0 to 30 dB is about 2/3 of the fader length.

I start with a 10-12 point, 5dB step table, but the 0 to 20dB is critical and realize that the audio taper from my fader is strange in this area, for example the 5 to 10 dB distance is smaller than the 10 to 15dB.

5dB table is accurate at the 5dB step spot but not between, so I decide "super accurate table"

Plus I have two fader so i measure both and made an average table



I have some listening test with stereo track send to both fader, channel full paned L/R, but unmatched level is made pre fader (test for 5, 10 and 15 dB L/R differential)

Then I compensate with fader, link them (group fader in DAW), and move one,  the second fader follow the the touched one with accuracy and keep the relative gain with success.



The result is a solid L/R balance without excessive floating center. I think the audio log taper tolerance is the most important factor in this effect.

I don't measure this, but it sound excellent to me, let say not more than +/- 3 ° in my 60° equi triangle monitor installation. Of course it's not so accurate at the bottom of the fader, but I don't care, and I'm not sure a more accurate table will resolve this

Anyway stereo tracking is WAY better compared to my actual stereo fader loaded in the desk.



The matching between DAW fader value and real analogue attenuation is the other aspect of this new table tool, and it work fine

I still have 4dB offset from reading value because my fader DAW is +6 max, but I don't care.

I think "relative" (as dB are) and if I reduce 7dB in the DAW my audio fader move down at the right position to reduce 7dB too



On side effect I think I can't solve, it's the DAW interpolation value when you are in the "positive" side of the fader (0 to +6)

when you are in this area with one fader the other (linked) folow closer and closer to reach the +6 at the same time, killing the relative gain.



For me this function is a FULL success, exactly what I'm looking for, Thorsten you are a MASTER.

Maybe at the moment i'm the only one that have some interest in this but i'm sure all of you will find this useful for some function, like matching a specific dB scale label in your front panel even if it's only a DAW remote, or have some custom curve response under the finger, super accurate in some area...



Tks a lot :thumbsup:

 

[zamproject]

UPDATE

Proto 2

quick spec:
-motor analogue PI driver
-analogue touch detection
-512 steep (9bit) without jitter (can be better with shielded cable from ADDA)
-cross talk digital/motor to audio ... less than my console noise floor !!!
-acoustic noise... did the fader move ?
-response time better than 120ms for 100%travel 100mm
-response time better than 80ms for 100% travel 33mm
-never over shoot
-two automation pass with complex audio material result in null phase test 50dB below my line level, in static condition of course (when fader reach the target)
-to null audio under my console noise floor with two automation pass, I don't need to trim one more than +/- 0.01 dB !!!


here it is !!! https://www.dropbox.com/s/o6v29atn209kyxi/proto%20II.mov?dl=0


Zam

 

[Spencerleehorton]

This looks great!

 

[gato]

Great song choice! Great work! I've been following your efforts at midi box, but I'm still in the reading about PID phase. This is such a tremendous accomplishment!

 

[audiomixer]

what a great success!
I wonder what it will take to make that available.....

cheers, Michael

 

[zamproject]

tks all for support

Great song choice!

if only make this working as easy as picking the song 

I wonder what it will take to make that available...

I'm on this since more than 6 month, the next step is to order one hiend TKD fader, then order V1 pcb, then evaluating one fader pack for few month "in real life" then building a 8 fader pack (with 8 tkd fader investment...)
Unfortunately I'm not in position for the moment to think about availabilities.

Best
Zam

 

[zamproject]

Hey
I have one TKD conductive plastic motor fader loaded since yesterday
Just amazing.
Excellent mechanical which increase the positioning accuracy spec
Also better torque motor, everything faster by about 30%
And finally, the conductive plastic really produce less sliding nose, which now is way below my noise floor !

This project grow up in a nice way 

Now It's time for real PCB batch and I need to think again around mechanical integration as few things changes since the beginning

Zam