Regulation

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JoPo
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Joined: Mon Apr 29, 2013 4:43 pm

Regulation

Post by JoPo » Fri May 15, 2015 12:54 pm

Hi !

I'm trying to build an auto gain feature. As I explain on Z : http://forums.planetz.com/viewtopic.php?f=15&t=33699 , my professionnal job is to program, fix industrial automatic mashines. And there is a very important feature some mashines must achieve ; called regulation. For instance a speed regulation like in modern cars : one want to drive at 90 km/h if the road goes up, the system will compensate the slowing down by accelerating the engine ; if the road goes down, the car will want to go faster, the system will decelerate, etc...
One can regulate a lot of physical value : temperature, pressure, depth, speed, position, and ......... sound level !!

But I must admit that I can regulate easily temperature in an industrial mashine because a regulation function is provided in the computer software, whereas in modular, with all the modules we have, I'm pulling out my hairs !

Could someone show me an example ?

As explained in the Z topic, I'm trying to find way to compensate the level in a filtered delay feedback path : when one filters a lot the feedback delay signal, it becomes quickly too low, which is normal... This is the point I'm trying to find a solution : having an 'auto gain' in the feedback path for trying to keep it loud enough. to have a very loooOOng loop even if I filter a lot the feedback signal.

Could someone make an auto gain function in modular and post it here ? I know that for some people here, it would be easy and done in 5 mn..? If you have those 5 mn, of course ! :mrgreen:
regul.png
regul.png (10.4 KiB) Viewed 22713 times
Thanks a lot !

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cwmod
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Re: Regulation

Post by cwmod » Mon May 18, 2015 8:31 pm

Hi JoPo!

Why not use a comp, as Jamie suggested?
Like this:
Image
You can download the patch here.
-Audio example-

(forget about the reverb, just the delay, filter and comp modules are important )

Edit: I just saw your P comment "Something more radical" - what exactly do you mean?
I cannot realise what you wrote on your attached image btw.

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JoPo
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Re: Regulation

Post by JoPo » Fri May 22, 2015 8:03 pm

Ooops !

Sorry ! I think I'm a bit late to answer !

Thanks to answer, Roy !

Yes : for sure it works fine with a compressor and I must say your audio example is definitely convincing.
But I'd like to build the function.
I would like something crazy : would it be possible to have a modular or device which would output any input signal at a setable level. Let's say I want -3bd constantly at the output. If, at the input, the signal is -16db, the device gives a +13db gain, If, at the input, the signal is -1db, the device mesures it and low the signal at 3db at its output. --> constantly the same level at the output, whatever how the input signal changes.

In industrial machines, this function is everywhere, as soon as one needs to regulate any physical size. You may find it also, in modern cars : there is a speed regulation : you adjsut it to drive at 90 km/h, what ever the road goes (flat, up or down), the speed regulation function will take care of the real car speed by measuring, calculating the difference between the measure and the asked speed and then adjusting (like normaly your foot) the accelerator to have the difference between speed measure & asked speed (called the error) a small as possible. In industrial automatism, we speak about a closed regulation loop : http://en.wikipedia.org/wiki/PID_controller, you have the image like this :
Image
Proportionnal, integral and derivative terms are there to increase accuracy and make the system as stable as possible. But I think that by adjusting attac and release, they become not compulsory.

If you have air conditioned in your room (which can make hot or cold air), you'll have such a device to keep room temperature always what you asked. If you open the door, cook something with hot sauce pan, it will try to keep the room at the temperature you asked.

Here, you can watch an incredible position regulation :
http://www.gralon.net/actualites/buzz/b ... re-446.htm
There is no video fx or truquage, it's a robot arm with a computer and physical sensors. The sensors measure the dancing guy perturbations, the computer calculates the speed it sent to 3 engines (one by axis) to keep the glas unmoving.

Let's say the output level is the unmoving glas, the sensor is an envelope follower, the computer and the engine (VCA, I guess) are what I'm looking for ! :mrgreen:

It IS what compressors do but I never could adjust a compressor to have constant level output if the input signal goes from -20db to -0.5db...

Thanks for reading !

Now, I'm going to study your patch which, after watching closer, seems maybe to do the job........ :?

jhulk
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Re: Regulation

Post by jhulk » Sat May 23, 2015 11:06 am

basically your after a active sensing expander limiter

if signal is below -3db expand to -3db if signal is above -3db limit to -3db

so it would switch between the 2 la2a style which uses ldr source and uses a threshold for limit if the limit is reached it acts like a limiter if the limit is not reached it acts like a compressor to compress to the limit

could you not use a compressor then limiter in series to do the same function

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JoPo
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Re: Regulation

Post by JoPo » Sat May 23, 2015 3:22 pm

I continued to make test, today with Roy's patch. And it is very close from what I'm looking for !
I added 6db LP & HP filters in serial in the feedback loop, the more the filter slope is soft, the more the result is good and evolve from a loop delay to the next.
As always, it seems to be less complicated than what I imagined.

Jhulk -> Yes ! That's it !
I don't get what you mean by "the 2 la2a style".... I don't have a huge knowledge about sound processing, I'm learning every day. And does "ldr" mean "lightdependent resistor" ? (That' what I've found !) :oops:

In your solution, would the compressor and the limiter work together or would they work one after the other ? If the signal level has to be increased, the compressor works alone (anyway, it will !) and if the signal level has to be decreased, the limiter should work alone and compressor must be switched off ?

Thanks a lot for your help, advices, devices and all, jhulk and Roy !
I guess that what I'm really looking after is how a device like the Meldaproduction "MAutoVolume" works inside and reproduce it in modular.... :mrgreen:
http://www.meldaproduction.com/plugins/ ... AutoVolume

I wanted to buy Scope SDK for my holidays but my bank account didn't agree with me... But SDK allows certainly to build exactly what one has in his brain...

jhulk
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Joined: Fri Apr 12, 2013 11:45 am

Re: Regulation

Post by jhulk » Sat May 23, 2015 9:08 pm

you dont need sdk you can do it with the circuit level modules sharc has provided nearly all the sdk building blocks as modular modules

you could couple a expander module with a exp0 mix1 module and set a control ranger so that the mix one module is fixed to -3db it wont let any more than -3db through even if you push it it will only let -3db volume on its output

then thats your limiter

the expander compressor then can be set to compress to the level but the limited mix1 module will only let -3db pass

you can the save the circuit level module and name it and then re use it as your own module once you get it to perform as you want then look into the sdk to make a dsp efficient version use a 1dsp clm

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JoPo
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Re: Regulation

Post by JoPo » Sun May 24, 2015 12:56 pm

Thanks a lot for helping me, jhulk but I must confess that it's sometimes hard for me to understand your meaning...
I made a research but didn't find any exp0 mix1... I have mix1 module but the 'exp0' is missing ! :mrgreen: But I guess you're talking about 'Mix 1' module.

Would you have time to build quickly your idea in modular and then post here the screen cap ? When you'll have time, of course ! I don't need it absolutely right now ! But it would help me a lot because english is not my language and I'm far from a professionnal modular synth builder ! :oops: I think I see which modules your say but how do I wire them ? This must look easy and natural for people who build modular synth as soon as they are awake but for someone like me, it's not ! Especially as I'm determined to understand how all is working because it's the best way to remember all those technical knowledge and improve it.

Thanks a lot ! :)

jhulk
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Joined: Fri Apr 12, 2013 11:45 am

Re: Regulation

Post by jhulk » Mon May 25, 2015 12:10 pm

expo vca/logvca=mix1 module it uses the db scale which is log/expo curve and is cheaper on dsp than an log vca

clm is circuit level module

open a circuit level module put inside that module a expander compressor take the audio input of the clm module and take it to the expander/compressor then its audio out to a mix1 module then the output of the mix one module to the output of the clm

now there are async inputs from the clm module you can wire these up to the async control inputs of the expander/compressor and the mix1 module

once done name module in the clm dialog and then delete the module it will ask you to save it save it to a user folder in the mod11 folders where all the modular modules are kept save it as expander/limiter

the next time you open modular shell it will be in your user section

this only works with bc modular clm shells there are no scope equivalent modules only bcmodular support this

then you can add it just like any other modular module then ad control rangers to the async inputs on the new user module

that way when doing presets you can custom the control settings per patch meaning you can limit or compress as much as you like per preset so you can fine tune the patches and recall them

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JoPo
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Re: Regulation

Post by JoPo » Mon May 25, 2015 10:41 pm

Done !

Thanks a lot, jhulk ! :)

dawman
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Re: Regulation

Post by dawman » Sat May 30, 2015 3:16 pm

I'm going to make one of these right now for my Project Window.
I also tried MAutoVolume from Melda but I need one in Scope.
Melda plugs are cool but he never allows a Bypass like Scope Plug ins have.
Keeps telling me to use a CC for wet/dry mix but sadly all of the adjustments for separate bands of a saturator, EQ or rotary effect are maintained.
Not very effective way to use a plug in like a stomp box or pedal, or the excellent Scope design.

Thanks guys.

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