Adding external filter - how do I do it?

[pinksoir]

Hey,

I'm thinking about adding a Steiner VCF to my stereo MB SID (this one) and I've been reading and searching but I don't really understand how to do it.

So I gather I'll need an AOUT_lc module. But I have no idea how to go about connecting up the filter or how it's controlled. I'm building an all-in-one keyboard/synth so I'd like to have the filter inside the casing. Would I need to add separate controls for it, or could the filter/resonance/mode be controlled via the MB SID control surface?

Also, I'm using the Optimized C64 PSU. I guess I'll need a new PSU.

Any help with this would be very much appreciated.

Edited September 9, 2012 by pinksoir

[Shuriken]

Hey,

I'm thinking about adding a Steiner VCF to my stereo MB SID (this one) and I've been reading and searching but I don't really understand how to do it.

So I gather I'll need an AOUT_lc module. But I have no idea how to go about connecting up the filter or how it's controlled. I'm building an all-in-one keyboard/synth so I'd like to have the filter inside the casing. Would I need to add separate controls for it, or could the filter/resonance/mode be controlled via the MB SID control surface?

Also, I'm using the Optimized C64 PSU. I guess I'll need a new PSU.

Any help with this would be very much appreciated.

A AOUT_NG would be the way to go. The LC will work too, but is more expensive. As for controls, please read the CV part of the MBSID V2 manual.

Edited September 9, 2012 by Shuriken

[pinksoir]

Cheers. I read that already and I don't really understand what it's telling me. I know that the AOUT will send CV to the filter. But I don't know how I would control the other parameters of the filter, for example the filter mode selection. Can that be controlled from the CS or would I need to add a rotary switch?

For example, in this image of the filter I want to use:

there seem to be CV controls for both res and resonance. Which is fine, I guess I can control those with the AOUT. What I also don't understand is how I'll atually connect up the filter to MB SID. On that filter there are inputs and outputs. How are they connected to the MB SID? As in, how is the signal routed to the filter and then back into the MB SID?

Thanks for the reply. As I said I don't really understand how any of this is done...

[Shuriken]

If you go to the external menu, you can control up to 8 external CV:

The witches are optional and not implemented.

As you have only 2 CV Inputs, this should be more then enough.

Edited September 9, 2012 by Shuriken

[rosch]

you use the switches in that menu to operate little relays that can substitute your switch. it depends on what type of switch is required and you'll need to make your own solution for this. maybe have a look at seppoman's SSM2044 filter board documentation (threads here and dokuwiki) he has used a relay there too (but just for clean/filter)

[pinksoir]

Cool, cheers. I think I'm gonna finish off my SID build first, and then look at the option of adding another filter.

[NorthernLightX]

I don't know if it would be an issue, but that VCF PCB picture has a major ground loop...

[technobreath]

Thanks for the reply. As I said I don't really understand how any of this is done...

Hehe, that's ok. what you really need to do is to read up on all the ucapps.de modules. That way you will get a better understanding on what the modules can be used for etc. Also read all the info @ midibox-shop.com as there is some info on alternative uses / setups of some modules that u might find interesting.

For controlling filter circuits from the SID, u need the analog output module. That module communicates with the firmware on the Core module in order to control the filter CV. That means, very simplistic explained - u replace the potmeters u got on the filter with electronic control.

As I am not into programming mios too much yet I don't know about the switches, and I don't have a SID with filters myself either, so I don't know the details - but since u ask about how this all connects i can tell u a couple of things as a summary:

potmeters is replaced by signal voltage from AOUT module

U can make the SID function as the rotary switch also if u implement it in the application (I don't know what's in there already..) This is done with a DOUT module and relays - here is where the additional info at smashtv's shop illustrate it very good.

But the only way is really to read up on the modules if u want to learn how this works. Midibox can do a whole lot of things, and also non musical things it was never intended for - it's all in the firmware - much like a PLC - u input a signal and the brain processes it in it's program and send out another signal. Basically :P.