synthy filters for guitar..

[deadastronaut]

ok, for my next trick i shall be breading up the 9v ms20...and then adding lfo.

tinker, tinker...

[nocentelli]

Excellent: Currently got another MS20 on the breadboard in an attempt to get an envelop filter out of it, but please share your LFO findings.

[deadastronaut]

okey dokey..will do.

breaded the ms20 twice with no joy though....hmmmm...

[nocentelli]

Is it the Escobedo version you can't get to work? I used the Eric Archer schematic -

http://ericarcher.net/devices/diy-lpf/

I used the rail splitter and rail-to-rail opamp specified in the schematic, and initially had some confusion because the 4.5v vref supplied by the rail splitter is labelled as "0v" throughout the schematic. Once I got that sorted, it worked fine. You can omit the mix pot for guitar use, I just connected the 33k/10k junction from the OTA output to vref via a 10k to simulate 100% wet, and left off the dry path from the input->output mixer.

[deadastronaut]

Hi leo, yep its the escobedo. one......its still not having it, i'll attack it again later.....probably pilot error..


that eric archer one sounds cool,  but i have the bits for the escobedo one...

Haven't got  'darlingtons' and other IC....at the mo, so i'll persevere a little with this for now...


have you got your envelope going yet?..love to hear it.

[garcho]

D'Astro, check out the Cliff Schecht version. single side MS-20

[deadastronaut]

well i think i'll have to go with something other than  a 13700n filter...tried  4  IC's...breaded it 3 times ...no joy..bummer

i never had any joy with these IC's, even when i tried the mutron V a while ago either...so they are either fake or fried....or i am more dumb than i thought..   (quite plausible)

anyway....

[garcho]

Booooo! Sorry to hear.

Random online filter help:
Analog Filter Wizard, courtesy of Analog Devices.

[deadastronaut]

^ cool...

[nick d]

          I built an MS20-type filter using LM13700 in a synth/noise box with dual LFO's a while back , just tried it out with guitar . It actually sounds pretty good IMHO , especially if you like Hawkwind-type stuff . I have posted a clip on Youtube , should be up in a while . A minor complication regarding stomp-box use is that it runs on +/- 12 V , but I'm sure that can easily ( ! ) be sorted . The VCF is based on one from the EFM Wildcat synth , the LFO's are from MFOS , as is the noise generator . Very noisy , very lo-fi , very fun !

[deadastronaut]

^ yep i like old hawkwind stuff...and red shift, tangerine etc...i mess around with reason synths quite a bit too..

look  forward to hearing it man..


ive temporarily gone back to the dual Q&D for now...sounds pretty good..

[garcho]

If you find a way to get the farty distortion down, let us know.

[nick d]

             Right , I have posted a clip on Youtube of this MS20 box . Can any of you wonderful people tell me in simple words how to link it to here ?
             I've had three tries , all I get is " Invalid Youtube link " . Please , help the Noob !

[deadastronaut]

copy the link at the top of your youtube vid  (url )...not share etc...

then choose youtube from here (top left)

then paste your copied  link between the brackets...

[nick d]

[yohttp://www.youtube.com/watch?v=gTjcnvy31zI&feature=player_detailpageutube][/youtube]

       If I've got this right , you should see a demo of some MS20 tomfoolery ......

[nick d]

 

        Hmmmmmmm.......... nth time lucky ?!?!

[nick d]

      Ha ! It worked at  last ! Rob , you are a gentleman and a scholar !

      By way of explanation , the other boxes are :-

              Middle - by-pass loop switcher
              Left - BMP type fuzz
              Right - A boost , needed this to make up for a slight loss of volume at min resonance .

             The controls on the filter/LFO/noise box are marked and should be ( ? ) self-explanatory .
             The demo also includes oscillation at resonance and a bit of noise gen sillyness .
             

[nocentelli]

Cool vid - which MS20 schematic and which LFO did you use?

[nick d]

           I downloaded the EFM schematics from a site which I have totally forgotten the name of - the schemos had a lot of errors and missing values , so I had trouble getting it to work properly . The main snag was that the resonance control worked like an off/on switch !  Then recently , I found a synth site called Lushprojects - they do a module " Lushone " , which was practically identical apart from the resonance section . I made the appropriate mods , the end result is what you hear !
           The LFO's are from " MusicFrom Outer Space " -what a great site ! - look at the " Oldies but goodies " section - there is one called " Super-Simple LFO " - I used that but cut the Saw/Ramp bit . The NoiseGen is MFOS , not sure which one .
            If you look at any of these VCF's , the CV is input via a 100K res usually . To use multiple LFO's or other modulation sources like envelopes or exp. redals , just add more 100K's .
          I have not yet tried a 9V version , there is one a few posts back by Cliff Schecht - looks slighty more complex , but a similar idea . It has the bonus of a boost on the input , which would solve the problem I had .
          I think the only issue in using 9V instead of +/- 12 might be a smaller voltage swing from the LFO , giving a milder effect . Possibly reducing the 10K resistor(s) on the 13700 current inputs could fix this ?
          I am going to have a go at a 9V version , with more modulation possibilities - a triggered EG would be cool , perhaps a random LFO as well ?

[garcho]

The LFO's are from " MusicFrom Outer Space " -what a great site ! - look at the " Oldies but goodies " section

Most of his projects include LFOs, there's a ton of stuff on that site, don't be afraid to adapt some of that simple synth stuff to guitar.

I have not yet tried a 9V version , there is one a few posts back by Cliff Schecht - looks slighty more complex , but a similar idea.

That version has a nice single sided current source, it's a benefit of Cliff actually being an engineer.

I think the only issue in using 9V instead of +/- 12 might be a smaller voltage swing from the LFO

+/-12V = 24V. 9V = +/-4.5V. kinda big difference.

Possibly reducing the 10K resistor(s) on the 13700 current inputs could fix this ?

Be careful! Too much current and bye bye OTA