I had this crazy idea of making your own analog filterbank!

Elzerk

Elzerk

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Nov 8, 2011
Heyall,

Yesterday I got this idea in class, one student was trying to biuld a wahwah effect filter to his guitar pedal and when I saw the circuit diagram, and how easily it was made made me wonder. "What if I look up the filter types from the internet, buy the components for each one and build them, then just attach all together and make a filterbank?" I studied electronics for 3 years and now I study to be automation mechanic. I have a friend who got really excited about the idea (has background in electronics and electronic music) and he was ready to try out these circuits shown in internet. What I've gathered the filters are commonly made with a op amp and couple of condensators or coil's. I'm still wondering if it's possible to make a cutoff filter to those? And how we're able to switch between serial and parallel and so on. Switching between filters is easy with a knob cause they all are so small circuits, usually work with only 9V too.

So if you have any tips, advices, or links around the internet for different filter types or other circuit diagrams or just about anything related, don't be afraid to point out!

Hopefully we find something really alien effects, harmonics, distortions and filter types never found before!! EVERYTHING WILL CHANGE WHEN THIS FILTER UNIT IS READY! We gonna experiment the shit out of this!

(Or it ill be just shit.)

Cheers!
 
Well, I have to say that I have an Electrix Filter Factory and thought I would use it a lot (and will when I get Windows 7, LOL) Or I could use it under Linux, it's just that I don't produce in Linux only do live stuff. Don't expect everything to change. There's a lot to be said for the sound of analog filters but there's a lot to be said for the ease of use and complex automation and routing, redundancy capabilities of digital filters.

I too studied a bit of electronics and have always been tempted to make these guys - a hell of a lot cheaper than a Sherman! Making it MIDI or voltage controlled (from a soundcard, you just have to remove any DC filtering) would be ideal but definitely not where you should start.

Umm yeah get your schematics from the DIY community, it's totally doable and many have done it. Complicating factors are that this was a much more common hobby 30 or 40 years ago and many schematics are out of date and use components that no longer exist - with a serious background you can figure out replacements but you're going to have to know how to calculate appropriate changes in resistor and capacitor values as well...

You'll see the different types like Butterworth, etc. Controlling the cutoff frequency is generally simply a pot. Note that not all the schematics you find are meant to be controlled musically - many of them are for crossover networks, noise filtering, etc.

Multimode filters would be much more complex and for production you may as well just build lots of different filters and wire them together via TS cables (or TRS if you really want to build in balanced signal circuits :mrpanic:) This is a more flexible "modular" system anyways.

Whatever you do, make a 24dB/oct notch filter - that's my favorite part of the filter factory, it's really quite nice. But so is the HP...and the LP is soooooo warm at 24dB/oct...

If you are technically inclined like this you may consider breaking the bank and ordering some kits from PAIA - very helpful if you've never completed a large scale circuit.

AND YOU SHOULD BE USING PURE DATA (free) OR MAX/MSP (don't use it) - in which you could sorta "test" different configurations or just make some crazy sounds.

cheers,
J.P.
 
Yes I got that feeling too that this stuff is old as fuck. But whatte fuck sherman costs around 600€ so why the fuck wouldn't I give this a go?! Gotta check the internets around. Thanks for the post though
 
I'd say try and get a book. I'm building a hardware distortion unit at the moment and a lot of the schematics on the internet have problems/mistakes. if you can find a good schematic thats been published its a much safer bet, either that or talk to someone whos used an internet schematic and can vouch for it being reliable.

The only other thing i'd say is generally you dont save as much money as you think. if you actually want a sherman you'll save money/time/hair just buying one.

But let us know how you get on and post some schematics etc it'd be good to see how it goes. Good luck.
 
Don't just search for filter designs. Search for guitar effects schematics, and work from there. They're all in the audio domain and generally designed to sound nice, rather than be an exact filter. Crybaby is really easy. So are many distortions (tubescreamer, big muff) and even some delays and reverbs. These can provide a good place to start experimenting.
 
After browsing guitar effects and filters from the nets endlessly, makes me just wanna buy sherman. :D But I found pretty much schematics and nice little ones that could be handy when combining many filters and effects. Now it feels pretty big job to aim but just gotta try those out one by one. I think there were pretty nice different distortion elements to be built at the diy guitar related sites. Just gotta take a one step at a time.
 
once you build a few of the easy ones it gets a lot easier as you start to recognise parts of the circuits and get ideas for your own mods. also, a good tip is to spend the extra time to place your finished board in a metal chassis and mount the knobs and jacks. its an overlooked part of the process, and you'll be thankful next year when you have a few good diy pedals, and not a couple of unidentifiable boards with pots and switches hanging off everywhere. i've a whole bucket filled with those :/
 
I haven't given up this crazy idea yet! Just ordering some components and after that gonnuh start building the first typical filters. Waiting to see how it'll work out.
 
I built my own modular synthesizer.

I would avoid running of 9V, build your own ±12/15V bipolar PSU. It's a good start if you want to get into synth DIY.

Here's my behemoth (The bottom row of modules are various types of filter, many cloned off old classics such as the Arp 2600, old Korgs etc. The middle row is mostly modulation sources, and the top row, oscillators/mixers etc.)
IMG_6750.jpg


A couple of forums I'd recomend which have synth DIY sections; muffwiggler and electro-music (.com)
 
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I just had a look, I have a couple of professionally manufactured filter PCBs kicking about in my workshop. A Buchla 291 bandpass (also has option to support lowpass and hipass) - rightmost module on the bottom row of my pic, and a Buchla 292C Lopass gate - 2nd and 3rd modules on the bottom row. Both boards require VTL5C3 vactrols, which can be expensive, and fairly hard to find. But when you see how much a Buchla synth will set you back, it makes it all worthwhile. PM me if you're interested in the PCBs.

There's also YuSynth who posts layouts so you can etch your own.
 
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