Musical filters for the producer/dj

[Optical]

Recently a friend of mine brought an Allan and Heath zone X2 DJ mixer wich has built in HP, BP and LP filters with a resonance control, they sound great! I also have many VST filters such as PSP nitro, Anteres filter and TC native Filtrator but would really like a hardware filter..

I was thinking about building one of my own, i have built a sweepable HPF using a sallen-key design but didnt sound too great.. i didnt put much effort into it.. does anyone know of or able to design any good tunable filter designs? i know Rane publish their DJ mixer schmatics but i dont think any of them have filters built in..

Thanks
Matt

[mhelin]

Well, Oakley Sound in UK sells inexpensive PCB's for Moog style VCF, look here:
http://www.oakleysound.co.uk/super.htm

[mhelin]

Also synthtech in USA have some good quality kits, listen to the samples of this triple filter:

http://www.synthtech.com/motm410.html

[Optical]

well i guess thats a start.. its a bit over complicated for what i was thinking of though.. does anyone know if the allen and heath filter implementation is analog or digital?

[daz007]

Hi Matt,

Did you have much luck in building a decent filter?? I want to build my own mixer with filters so I'd love to know how you got on...

Regards,

daz (newbie)

[Optical]

well i built an analog 2 pole high pass filter using a sallen-key topology, it worked but i had summed the left and right inputs so it was only mono, to make it stereo it would need a 4 gang pot which i have been unable to source cheaply and easily..

it wounded pretty good, very thick with the resonance turned right up, but these allen and heath ones are much nicer, which makes me think they are digitally impremented, i think this because there is no volume fluctuation when you sweep the filter, with analog ones you have to match the volume when the filter is in an out of the loop which can be a pain on the fly if you know what i mean..

i plan on building my own mixer with filters one day too, but until i iron out all the annoyign details like these im not going to bother starting..

anybody know of a simple DSP chip that might be able to take care of something like this?

[JustJohn]

Download the lm13700 datasheet. its got some ideas using transconductance amplifiers...

[MrGuitardeath]

Hey pretty cool effect these give.

Check these out:
http://www.musicsynthesizer.com/DIY/Grant/Borg.html

At the bottom it takes you back to his home page. I've foud the best place to start is a good old fashio DIY site rather than looking to build kits.

It looks like he's got some killer stuff there and invented some of it himself.

You should also check out the analog Synth kits at PAIA:
http://www.paia.com/

Not quite the same thing but I'm sure about anyone working in music could find planty to do with one of those analog synths......there's something about them that brings to life those old bizarre sci fi mopvies from the 60's and 70's.
Flash Gordon lives on!

[daz007]

Hi,

I just found a copy of the Active Filter Cookbook by Don Lancaster in my college library,great great book! Thinking of using a design with transconductance amplifiers and op amps....it has low,high and band-pass outputs,with voltage control of the cutoff frequency and resonance. Nice...

Regards,

daz

[Optical]

sounds good, any chance of posting the schematic?