EDP Wasp VCF as a Pedal...WOH!!!

[Strategy]

I saw a few mentions of this in the archive but am somewhat shocked that this project has not taken up residence as a pedal project!
Just got mine tested this afternoon - from this project: http://modular.fonik.de/pdf/Wasp%20Filter%20clone.pdf
Some of you who belong to electro-music or muffwiggler forums will know Fonik from his popular synth projects, pcb's, and knowledgable contributions. This PDF is for his version of Juergen Haible's (RIP) version of the VCF in the EDP Wasp synthesizer (here: http://www.vintagesynth.com/misc/edp_wasp.php)

Pedal friendly aspects -
- Runs on +9V!
- Doesn't sound (so far) like it needs the typical boost - most synth modules run on hot signals and so putting guitar/line level into typical modules sounds nasty. I plugged right into Wasp VCF and it sounded like exactly the right thing.
- Offers LP/BP/HP/Notch, there apparently is a way to bring all the outputs to the panel although this is not needed for guitar pedal prob. The 1P12T rotary switch wiring is pretty painless (I hate rotary switch wiring..)
- Here's the interesting thing for guitar/rhodes/bass etc. -- at least in the Fonik/Haible version - switchable overdrive.  

about this, the pdf says:
Jürgen Haible says: It sounds considerably different than the ordinary SEM-type state variable
filter. The maximum Q is lower on the Wasp version. And there is an additional distortion coming
from the CMOS inverter nonlinearities. This distortion is gradually increasing with input level,
and you can slightly hear it way before the circuit actually clips. The CMOS inverters seem to be
the dominant source of distortion; the CA3080 input dividers are rather on the save side.

The over drive makes it sound like really shredding resonant wah. Imagine the musical breakup of a Red Llama crossed with an analog synth and you are close. I am going to make this into a typical enclosure and add an expression pedal input, but fans of unusual wahs could just do this in a wah enclosure.

There is onboard CV input, which I'm going to leave as an input jack so I can connect it to moogerfoogers, etc. This could also be subbed out for a hardwired LFO or envelope follower for those that don't care for patch points or need onboard modulation.

it's not much to look at right now, but I will post some sound files this week. HIGHLY recommended for filter fans

Strategy

[armdnrdy]

Sound sample please!

I've been looking at ASDR's and filters to incorporate with guitar effects.

[Isak]

I build the wasp filter, didn't liked the sound of it very much.
The cool thing about fonik wasp design that it can run with a single rail power supply.
There is a better sound filter but it with (+) (-) supply.
Check it out...
http://www.analog-synth.de/synths/mod2/ms20filter/rene_ms20_filter_clone%20rev%204.pdf

Build it and sounds freaking amazing!

Cheers.

[deadastronaut]

cool, sounds interesting...

waiting on clips

[Strategy]

I built a 9V MS20 filter and it sounded good, but, the layout was not good and the project kept breaking and finally, had broken circuit traces, too much trouble to fix...Will try it again.

I thought the Wasp filter sounded great but the sound of it is intentionally low-fi, especially with the Drive activated.

I had tried earlier version (Doepfer) Wasp filter and it was not as flexible, because the overdrive was not switchable...It's really good to have this on a "lift" for options.

Will make sound samples in the next day or two!

Strategy

I build the wasp filter, didn't liked the sound of it very much.
The cool thing about fonik wasp design that it can run with a single rail power supply.
There is a better sound filter but it with (+) (-) supply.
Check it out...
http://www.analog-synth.de/synths/mod2/ms20filter/rene_ms20_filter_clone%20rev%204.pdf

Build it and sounds freaking amazing!

Cheers.

[John Lyons]

I have to get mine finished. I built it from those documents.

[Strategy]

@JohnLyons, you'll see when I post photos that I'm using the board I bought from you

[John Lyons]

Heh.  Forgot about that. I made one since I was making one for you. 

[Strategy]

I added an expression pedal input to the cutoff frequency pot - using the "in series" style of doing this so that when the expression jack is inserted it switches off the pot - my goal was to record sound samples of this using a treadle type expression pedal so that the example of the wah-filter idea could be demonstrated. Unfortunately expression pedal didn't play nice with this control, the pot is 10kA and I think Moog and Roland expression pedals are usually 25k-50k so it just sounded wrong. I don't know how I'll try to fix this yet (or if I'll end up just leaving it off for now and building a 2nd Wasp vcf in it's own Wah enclosure!!!)

Anywho, will post sound samples with other modulation sources instead (LFO, analog sequencer etc.)

Strategy

[armdnrdy]

Strategy,

I might have something you can use for the expression pedal control.

I ran across the same problem recently. I needed to control a function with a certain amount of resistance but an expression pedal's 10K pot wouldn't cut it.

So I came up with this:

http://www.aronnelson.com/gallery/main.php/v/diyuser/Optocoupler+control.jpg.html

Depending on how the expression input jack is configured, this circuit can be used as a voltage divider or a variable resistor. You can configure it max resistance heel down or toe down.

The LDR and LED (available at Tayda) along with the components I chose (depicted in the circuit) allow the 10K expression pedal pot to change the optocoupler resistance from around 400Ω to over 100KΩ.

The pedal jack is switched so when there is no pedal plugged in it will keep the LED at max brightness which will keep the LDR at least resistance. When a pedal is plugged in +V is transferred through the pedal as a voltage divider which varies the resistance of the DIY optocoupler. End result....100K expression pedal.

You'll have to breadboard this circuit with your expression pedal and play with the resistor values until you get what you need.

[Strategy]

wow - I'll try this, thanks!!!
Strategy

Strategy,

I might have something you can use for the expression pedal control.

I ran across the same problem recently. I needed to control a function with a certain amount of resistance but an expression pedal's 10K pot wouldn't cut it.

So I came up with this:

http://www.aronnelson.com/gallery/main.php/v/diyuser/Optocoupler+control.jpg.html

Depending on how the expression input jack is configured, this circuit can be used as a voltage divider or a variable resistor. You can configure it max resistance heel down or toe down.

The LDR and LED (available at Tayda) along with the components I chose (depicted in the circuit) allow the 10K expression pedal pot to change the optocoupler resistance from around 400Ω to over 100KΩ.

The pedal jack is switched so when there is no pedal plugged in it will keep the LED at max brightness which will keep the LDR at least resistance. When a pedal is plugged in +V is transferred through the pedal as a voltage divider which varies the resistance of the DIY optocoupler. End result....100K expression pedal.

You'll have to breadboard this circuit with your expression pedal and play with the resistor values until you get what you need.

[chemosis]

yes i always wanted to build this wasp filter for guitar and though about starting a forum on it but you already did. i suck at vero though and wish someone made a pcb for it. damn wonder if i can convience someone to sell pcbs for the wasp. i love my funk-a-duck with humbucker it is awsome and its a ms-20 filter variant. oh the polivoks filter is another that i always wanted to try on guitatr but cant find a pcb for it. i used to own a electrix filter factory and that worked good for guitar so why not try the polivoks filter also for guitar.

[Strategy]

Funk-a-Duck is really cool.
If you download the Fonik WASP vcf pcb layout document (I believe I posted link in the thread?) You can find people on this forum and others who will etch a single-sided PCB for you. It wont cost very much, I recommend this route as this is a very simple circuit, easy to assemble and trouble shoot (if necessary) in the single sided format. Really only take a couple of hours to build completely.

Strategy

[chemosis]

GREAT THREAD ive benn wanting to hear this on guitar along with a tim e ms-20 sallen filter. i love my frostwave funk a duck with guitar which is a ms-20 variant yea u have to use humbuckers but its my favorite filter for guitat and ive owned alot of filters. i used to use a electrix filter factory with guitar and a boost and that also worked well. why dosent someone post some videos of the polivoks filter with guitar and the wasp filter with guitar or at least sell some pcbs for these projects.

[snk]

Hello,
I am resurrecting this thread, as i am building a WASP VCF clone, and i have every component except the BAT85 diodes 
Are BAT85 mandatory, or could i use 1N5817 or 1N5818 as dropin replacement ?
Thank you in advance for any help

[anotherjim]

Short answer is to use any Schottky diode with Vf less than 0.6v. Fast types will be better.

Those are input protection diodes. They should help prevent any excessive input from upsetting the CMOS U1 chip.
The filter will work no differently with them or without them.
The 4069UB chip already has protection diodes. However, if they ever act, the chip can stop working -  act like it's dead - until power is removed and restarted. The on-chip diodes are ordinary silicon. Using lower Vf Schottky protection diodes should mean the on-chip ones don't get to conduct with an over-voltage input and the chip should carry on working.

[snk]

Thank you very much, Jim !
Would you have any suggestion for a fast Schottky diode with Vf less than 0.6v ? I will make a search myself, but i am far of a diode expert

[anotherjim]

I'm sure your 1N5817's will work just as well, although they are bigger, otherwise I'd get any of those little BAT types.

If you do the input differently, ordinary silicon signal/switch diodes like 1N4148 will work.
The input resistor doesn't have to be before the input capacitor. Move it to the chip input side.
Use 2 resistors in series equal to the original. So it's 33k then x2 15k. Wire the protection diodes to the + and - supply connected at the centre of the 2 resistors. This means there is a 15k resistor between the protection diodes and the chip input. That means the protection diodes will tend to act sooner than the ones in the chip, even though they have similar Vf.

[snk]

Hi, Jim
Thank you for your reply.
As i have read that you stated that "the filter will work no differently with them or without them", i have built the circuit, leaving some empty sockets for the diodes, and i have ordered a couple BAT85. I may also try with 1N5817 (but as far as i understand, as they are protecting the chip from overload, i will never know if it works... unless something bad happens  ).


I have built the circuit according to a schematic from guitar-fx-layouts.
It somewhat woks, but some things are wrong, and i can't figure out if it is because i messed up with the veroboard, the wiring, or something else 
- The dry signal is always present ;
- the "wet" signal (along with the dry signal which is always on) is much lower than the bypassed signal (i woudl say at least half unity gain).

It is the first time i used a 1P4T (which was in fact a 2P4T, where i used only half of it), but i don't think i messed up with its wiring (as it changes the sound when i switch the switch).
The resonance knob seemed to be wired backward on the layout, so i changed lug 1 and lug3 (in order to increase the resonance when turning the knob clockwise).
The distorsion works fine, as far as i can tell.
I have also added a clipping diode switch to chose from red leds or regular 1N4148, and it also works.

[anotherjim]

I'm not sure if I trust that layout.
Where is the signal input meant to be?
Is the 78L05 regulator the right way around?
Is there a schematic that the layout was for certain derived from?

I've never actually built the Wasp filter, for a couple of reasons...
Needs x2 fairly expensive CA3080 chips.
LM13700 should be able to substitute, but I can only find proposals for this and no evidence that it works properly or under which of the following conditions...
A, LM13700 at original Wasp 5v supply.
B, LM13700 with suitable alterations for pedal 9v supply.