nice diy vcf

[Steven_C]

I'm wondering if anyone knows of an easy to build diy VCF, designed primarily for injecting a line level signal into it, and doing cool filter sweeps, as I would really like one, as the studio I use at college has no such effect available!!! (we have a dedicated DAW, which has no plugins! it can't use any of the standard formats... vst, au, rtas, tdm etc, so I need a hardware solution!!)

oh yeah,  buy Australian made DAW's, help our economy! (but it won't be a flexible solution! But then again, it is cool using a hardware based studio, more 'real' knobs, and expensive boxes to play with!!)

oh yeah (2) I have some ca3080 chips lying around, waiting to be used!!

[pilo]

http://www.paia.com/9730.htm

this is a VCF?

[Steven_C]

yeah, but look at the price!!

I had a simple design on my old hardrive, I'll have to dig out those old backup cd's...

thanks pilo,

from Steve

(I think I'll put this on hold, as I think my Nova synth can be used as an analogue filter (VCF but digitally modelled))

[Lall]

Hi Steven,

If you want to make a VCF, you should take a look at the NE5517 datasheet (LM13600 and LM13700 are pin-to-pin compatible equivalents). This chip is a transconductance amplifier or in other words a current-controlled amplifier. With a few limited passive components, you can build a VCA, VCF, ...; schematics are available in the datasheets.

The current used to control the chip can be generated by a DAC. I'm pretty sure you can find 8-bits DACs with parallel input capabilities. If not, you'll find easily some DAC controlled by IIC.

Those chips have a quite broad application scope but are also well suited for audio. Moreover, they are not too expensive and are available in "solderable" packages.

Best regards,

Lall

[Steven_C]

Hey Lall,

 Thanks! I'll check this out!! :)

[Steven_C]

http://www.synthdiy.com/view/filecat.asp?type=4

I found some info here, they also have info on the SID chip! (6581)

[stryd_one]

I swear I remember TK dropping a hint about a VCF module for the SID....

[Steven_C]

Yeah, I think I remember TK saying he already had one.... not sure if he built it himself or not...

[Steven_C]

Another year goes by, and I haven't gotten any further towards building one!!!

Well here is a circuit I found

http://www.uni-bonn.de/~uzs159/ms20.html

and I think this is the PCB for it, as well as some mods...

http://www.analog-synth.de/synths/mod2/ms20filter/ms20filter.htm

Oh well wait another year to see if I've bought the components yet!

[Screaming_Rabbit]

Hey Steven

Sounds like you're working with Fairlight  ;) ... great system!

Why not take an older PC (a 1GHz P3 for example... almost for free),  uninstall everything not needed (cleanup the OS), install Steinberg "VST Stack" and loop the digital signal from your DAW over the PC-Soundcard and back into your DAW? .... Then use all those nice PlugIns  :D

BTW: That's how Fairlight implemented VST into their "Dream" Series. ;D

Greets, Roger

[Sephult]

Hey I haven't built my SID arrangement yet, but I am sure you are able to use the input to route through the filters of  the SID.  

[Steven_C]

Hey Roger,

That's how Fairlight implemented VST into their "Dream" Series.

 I wasn't aware of that! I finished Tafe last year, so I don't use the fairlight anymore... I never figured it out anyway, I ended up doing all my assessments on Protools.

Sephult, you're probably right... but It'll be a while before I read all the sid stuff or get round to building a sid module (or two)

[illogik]

cool diy vcf's:

http://www.musicfromouterspace.com/analogsynth/old_synthesizer.html

has multistate vcf and low pass vcf, pcb's; i've made both, only multistatevcf works, it uses LM13700

http://www.cgs.synth.net/

has steiner VCF; haven't made it yet but i think it's very cool and easy/cheap (cheap pcb available)

http://www.simple-answer.com/DIY.html

Buchla bandpassfilter; haven't made it yet but looks cool, you can

download pcb.

good luck and have fun!

cheers marcel

[Tanstaafl]

Here is a Fatman Mod that I used as a stand alone VCF.. it's cheap, hackable and works great... I have built quite a few for my MultiFatman synth.  Cost is about 5 bux USD.

lemme know if this looks like you want, I also have a pcb layout that fits on a very small board, and I could email it to you.

look here for the schematic

http://www.ggbnet.com/vcf.html

gb

[d2k]

and I think this is the PCB for it, as well as some mods...

http://www.analog-synth.de/synths/mod2/ms20filter/ms20filter.htm

Just made this fella and it sounds nice :) am I right in thinking that with the 2 CV inputs on the pcb I can control freq and res from an AOUT module? I have one in me SID - any one intergrated c/v control with SID yet?

Cheers Steve!

D

[illogik]

am I right in thinking that with the 2 CV inputs on the pcb I can control freq and res from an AOUT module?

Looking at the pcb, i think they are 2 CV inputs for the cutoff frequency (the cutoff pot is connected to the same point as the two cv inputs through resistors); so you can for instance connect an lfo and an envelope generator to control the cutoff

cheers marcel

[d2k]

right, but does that mean the aout module can be used here?? I dun know c/v and aint really used proper h/w analog synths before, and I def aint a patcher...so whats the hookup proceedure? from 1 of the 'V' pins on the aout brd to the cv input on the vcf? then i can make an encoder or whatnot control the freq?

[illogik]

sure that's whats the aout for; you just look for an cv output on the aout, wich you can hardwire (instead of making 2 patchholes) to one of the cv inputs on the vcf ( i think the points wich are connected to the 22k resistors allow for cv inputs with "offset"; you can "mix" the different cv levels with a pot, the 100k inputs are direct inputs>no cvmixing)

You can now assign a rotary encoder to the right aout cv output, depends on the application your using how that is done i guess.

cheers

[moebius]

Hi,

oh yeah (2) I have some ca3080 chips lying around, waiting to be used!!

Those are also used in ASM-1 VCF:

http://home.swipnet.se/cfmd/synths/friends/stopp/

Bye, Moebius

p.s. And for that PAiA, filter: You don't have to buy a PCB: http://www.paia.com/9730sch.gif

[nebula]

Old thread, I RESURRECT THEE!

I am curious if anybody has built the PAIA 9730 VCF, and if so, what do you think of its sound?

[opkod]

http://www.yusynth.net/Modular/index.html

look at this diy modular synth, you can make diy pcbs with ordinary component.

[stryd_one]

Hey that's a good one thanks opkod!

Very simple circuits with very common components.