DOD FX25 Envelope Filter

Schematic available here.
Added a second layout with Mark Hammer's mods from the DIY forum (here).

Electro Harmonix Knockout Attack Equalizer

"The Knockout is a powerful two-filter combination that can make your Les Paul sound like a Strat and your Strat sound like a Tele. Its secret...the Knockout has a 7 pole filter for sculpting the low end of your mids and a 6 pole filter to shape the top end of the mids. This provides incredible tone shaping. Use after distortion to bring out the heavy weight punch of the metal masters. The Knockout is also truly amazing on Bass."
Original FSB thread and schematic available here.

... and a layout with added Input & Output caps. (Will remove the one above later)

Frostwave Funk-a-Duck

"The Funk-A-Duck is an envelope control filter which can be used to produce a wide range of "synthetic" analog-ish sounds. The input causes a control signal to be generated, which goes up and down as the input signal loudness contour goes up and down. This in turn sweeps the filter frequency back and forth."

Output Level

Sets the output level ;)

Envelope (Down-None-Up)

Controls the amount & polarity of envelope modulation.

Input Range

Sets the input sensitivity, has major effect on intensity of effect as well as overall loudness. Important to set this so that when bypassing, the levels are about the same.

Res

Sets resonance of the filter. Can be turned up to actually resonate, either continually or when triggered by peaks of the input signal. This is one thing that makes the unit rather unique.

Frequency

Sets the filter cutoff frequency. It has a very wide range, so it is possible to have it set so NOTHING at all comes through. Also, when any of the other knobs (input, res, envelope, speed) are adjusted, the resonance freq moves, and needs retweaking.

Speed

Sets attack/decay of the envelope. When fully anticlockwise, the speed is FASTEST. Recommend using in this position, at least until one is familiar with the unit.

LP Filter / HP Filter

Selects the type of filter: lowpass or highpass. Unit will resonate in either mode.

Original FSB thread and schematic are available here.
I've used an LM13700 instead of 2 LM3080.
Drawing it was quite complicated and it came out quite large.
Always double check the schematic before building an unverified layout.
(You may be able to use an LT1054 based voltage doubler but I'm not sure about noise level)
Special thanks go to Digi2t (Dino T.) for drawing this and many other schematics we've been using on this blog.
Here's his video:

Roland AG-5 Funny Cat

Here is a "heavily modified" layout for the old and weird Funny Cat.
The original pedal sounded a bit...
Me and Gavin (Hozy31) have been working on this to try to improve the sound.
We added Moosapotamus mods, a buffer at the "Normal" side input to avoid "tone sucking" problems and a boost (SHO) at the SDS/Normal switch output that works only when the Harmonic Mover is switched off, to avoid volume loss when using the fuzz on its own.
Gavin has tested the final result and he's very happy with it.
There are videos of the original AG-5 on YouTube but we prefer not to add any here cause this version sounds quite different (in a good way)
You can find more infos and sound clips of Moosapotamus modded version on his website here.

Moosapotamus Dirty Bird

Here is a layout for Moosapotamus Dirty Bird.
You can find all infos and sound clips on his website here.

Madbean Sharkfin Filter (Maestro FSH-1 without Sample&Hold)

Here is a layout for Madbean Sharkfin filter side.
There is already a verified layout for the complete project but I've preferred to use a separated post for this one
24/08/16 Layout updated!
Moved bottom left 3K3 resistor up one row to connect it to 150n output cap.

Madbean Sharkfin (Maestro FSH-1 Filter, Sample & Hold)

Here is Brian's modified version of the old Maestro FSH-1.
You could buy his PCB here and find all infos about this project here.

Chunk Systems - Agent 00Funk

Lastgasp Art Laboratories Rattle Crow Restive Filter

Just saw this schem posted in the forum and thought it looked like a pretty cool effect. The original has a funky LED setup and uses the 3rd pole of the 3PDT to cut the 9V connection to the whole circuit. I have drawn this layout to fit our normal offboard wiring.

Info from manufacturer:

The "RATTLE CROW RESTIVE FILTER" (RC) is an effect pedal in which the filter is affected according to the size of the input.

Characterized by a wild and sorrowful tone.

The RC is a kind of auto wah, but it has hysterical and distorted qualities, a broken auto wah sound.

Death By Audio Evil Filter

Here is the layout of an unreleased DBA pedal.
You can find the original FSB tread HERE
Thanks to Anders for verifying it!

Here's the video of a clone:

Maestro MPF-1

17/10/2015: Layout updated and verified!

Changed 2 components values and added an extra capacitor on Bre's suggestion.

Thanks to Bre for the help and for verifying this!

- Changed 22u cap from pin9 to 2u2.

- Added a 2u2 cap between diodes and ground.

- Changed 4007N to 4007UBE.

HPF Technology HPF-Pre 2

I've had a few folks asking for active bass cutter circuit for couple of different uses. First, a lot of stoner rock enthusiast want to split their signal for two amps and some blues folks want to do that too. And since in cases like these, the second amp is usually a guitar amp, which will perform in a happier manner if we don't feed them the lowest frequencies. I got tipped off with HPF Technology's HPF-Pre 2. Even though the main aim for the design is to address issues with double basses, the circuit will work great on other applications as well. This design is open and for mainly that reason, i strongly recommend getting an original unit if you find use for this circuit. The price is more than just right, so your savings won't be much by building one. So. If you can, please support the orginal design.

I built one already to see if the board works with J201s and 2N3906. It does. The frequency pot should definitely be dual gang logarithmic taper.

A quick overview from the author:
HPF-Pre is a preamp with adjustable high pass filter and phase switch for use with piezoelectric pickups on the double bass. It is intended to address the primary issues faced by bassists when playing through mainstream amps and PA systems. Foremost, HPF-Pre is a preamp. Its high input impedance ensures proper buffering of the signal from piezo pickups. It is battery powered and housed in a tough plastic enclosure with internal shielding. An adjustable high pass filter tunes out the subharmonic “thump” generated by the plucked bass, which otherwise can drive ported bass speakers to over-excursion. It is also a useful tool for coping with adverse acoustical environments and PA systems with excessive subwoofer support. A phase (polarity reversal) switch is provided to help control feedback problems. It could also help when setting up systems with multiple pickups, or a pickup and a microphone. Series 2 of the preamp adds an output volume control and an LED battery status indicator. The volume control is handy when your stage setup requires your amp to be out of arm's reach. HPF-Pre is an "open" design. I sell the HPF-Pre at a modest price from my part-time home business. Otherwise, you are welcome to build your own.

Check the site and get the original from https://sites.google.com/site/hpftechllc/home

Mutron III

A few people have requested this, and I hope they all don't mind making links :o)  LED/LDR layouts are such a pain!

A very well regarded envelope filter that many think is the best sounding one of them all with this being based on RG's Neutron project files due to the unobtainium status of some of the original parts.  I have modified this slightly from the original because I didn't like the idea of the Gain pot and first opamp stage being permanently in the signal path of your effect chain, and there's really no reason why it should be now DPDT and 3PDT stomps are available so cheaply.  So I have made this one true bypass so just use your preferred method.

Some people have used two LEDs or vactrols to make this but I have opted for a single LED with the LDRs on either side, so you can just bend them to face the LED as you see in some Univibe type effects.  To get the best out of it the LED and LDRs need to be in darkness which obviously isn't a problem when the effect is boxed, but for testing before being boxed you will want to put a cover of some sort like a small purpose made cardboard surround to keep out the unwanted light.

For LDRs Javi suggested the GL5539 which is available cheaply and in quantity on eBay and is 40-100k light, 5M dark resistance.  But I'd suggest socketing them, and probably the LED as well so you can try a few in there and stick with the combination which sounds best for you.

The trimmer was included simply to allow you to fine tune the brightness of the LED which should allow you to tweak the best setting out of it.

The effect needs a +/-9V supply and so I have shown the usual voltage inverter board.  You can add 5 rows to the main board if you prefer but I thought this would make more sense and allow people to get it in a 125B pretty comfortably with the supply board stuck on an inner wall somewhere out of the way.  You can also omit that entirely and use a +/- 9V supply if you have one, or two batteries if you prefer.

The original included a rotary switch for the Mode selection, but there are only 3 selections and so this is easily accomplished with a DPDT on/on/on toggle which again saves lots of space.  If you go with my choice here make sure the contacts change as shown in the diagram.  Some of these switches have the opposite contacts in the middle position, and so if you get one like that you can still use it but you'll need to swap the poles.  So lug 1 becomes 4, 2 becomes 5, 3 becomes 6 and vice versa.  Then it will work fine.  And don't forget the link you need between lugs 2 and 4.

I couldn't find any marketing blurb for a 1972 effect (the year I was born) so for fun here's the patent blurb instead:

A sound effects generator for modifying a sound generating signal is comprised of a voltage-controlled filter having a variable peak response frequency for transmitting at a maximum amplitude those frequency components included in the sound generating signal that correspond to the instantaneous filter peak response frequency. The peak response frequency is determinable by a control voltage applied to the voltage-controlled filter; such a control voltage being proportional to the envelope of the sound generating signal as extracted by a control voltage generator. The filter peak response frequency is thus varied in accordance with the varying envelope of the sound generating signal.

Eh?  Start again please but slower.

And I have to say it really does sound fantastic in this vid.

And as per Javi's request this is as per the original with a 4 pole 3 way rotary switch for Mode, and with a simplified bypass that leaves the first gain stage in circuit.  Just a DPDT stomp is required for bypass, or SPDT if you don't want LED indication.  I left the charge pump board separate though because I just can't face adding any more links to it! :o)

Death by Audio Kill Kill Filter

The Kill Kill Filter is a dual filter pedal with a semi-truck of attitude! 2 identicle eq's can be switched back and forth on the fly for an endless seeming changing sounds as you play. Create a new lead sound and then another! Blast in a solo! Chunk out on a heavy riff! You call the shots! It's mean and evil and sounds absolutely amazing after a fuzz pedal creating some of the most seething intense tones ever heard!!!

You'll notice the wiring for the main stomp is slightly modified with connections for the LED switching shown in the layout.  You can use the rest of the usual offboard wiring diagram for the audio switching and so lugs 4 to 9 remain as normal.   So the main switch will bypass the effect completely and the Filter switch will select which filter is in circuit and which LED is illuminated.

Not my cup of tea but I'm sure you glitchy filter noise fuzz thing lovers will dig it,

Death By Audio Sound Saw

I would advise caution before you proceed :o)

This has been put together after a request, but it's based on a schematic of unknown origin so I don't know whether the scheme even works never mind the layout.

A couple of things do make me think it could be a good trace though.  The volume pots are wired in an unusual way which I have seen from DBA before, although for this layout I have changed them to the more usual volume pot configuration that we are used to, purely to remove unnecessary daisy chaining and so make connections simpler - their functionality in the circuit remains identical.  It also looks like a mish mash rats nest of a circuit, which again points to authentic Death By Audio :o) (just joking guys).

As this is a gamble at this stage, it may be one to do with pots in a breadboard first rather than soldering them, but as long as you know the score from the outset, if it's something you want then please let us know so we can verify the scheme and layout or bin the post entirely.

Update 12th April: Now corrected and verified so no longer a gamble :o)

Here is the schematic it is based on for those who may want to follow it

The pot numbering shown in the schematic is the reverse of the convention and so I have swapped lugs 1 and 3 where necessary.  As noted above the volume pot connections have been altered to our usual:

Volume 1 ground
Volume 2 output
Volume 3 input

Only the second stomp switch connections are shown in the layout.  The main bypass stomp switch is wired as per usual, and with a separate LED to show when bypassed.  Then the LED mentioned in the layout (assuming using bi-colour) displays the selected channel.

One of the LED resistors was shown as 100K which seems huge to me even for a ultra bright LED, so I've just included a single 3K3 resistor for current limiting, which can be used for a common anode bi-colour LEDs with stomp 2 switching the ground connections.

Anyway, enough waffle, here's the info about the original:

trash the system. make your fuzz pedal kill, kill, kill. everyone will scream in terror. here is the SOUND SAW. 2 unique channels of huge thick quasi-eq filters to intensify your wall of sound. blast your way out of the mix and sound enormous. the one channel of the SOUND SAW cuts a selectable frequency and boosts the hell out of the frequencies around it while the other is an active bass to treble blaster. LED of selected engaged filter dims when bypassed to let you know which channel is active. the SOUND SAW is capable of nice creamy tones or huge amounts of boosting, feedback insanity, cutting, sub woofing, room shaking, glass breaking frequencies to make you have the most intense sound possible.

Sound Samples:

Hyper Fuzz regular and then the Sound Saw comes on 352k mp3
Clean guitar into Sound Saw changing tones 256k mp3
Bass Guitar into Suppa Tone Bender into Sound Saw 444k mp3
Bass Guitar into Big Muff then Sound Saw 144k mp3

Mutron Micro V

As Javi liked the idea of the simplified controls I thought it would be worth adding a layout for the original pedal too.  It may seem strange with it being a "stripped down" Kraken, but it actually worked out a column wider using the Kraken layout as a template because removing the Attack pot means a resistor needs to go from the 3rd to the 15th row, but what can you do? :o)  Anyway the option is here if anyone wants to build this instead.

Madbean Kraken

We had a request to do the Mutron V or the Madbean Kraken so I decided to go with this one for the extra controls.  Info from Brian about his modification:

The Kraken is a modified Mutron Micro V™ envelope filter. The Mutron Micro V™ is the “little brother” of the more fully featured Mutron III™ having only a Range pot and a Hi/Low switch for the filtering. The Kraken expands the controls to include Attack and Decay for the envelope response. This is the only alteration to this classic and great sounding envelope!

Controls
Range: This controls the intensity of the envelope dynamics generated by your pick attack. Higher settings yield greater sensitivity, which in turn drives the intensity of the swept filter.
Attack: This control lets you dial in finer adjustments to the attack of the envelope. It is interactive with the Range pot.
Decay: This control determines how long it takes for the envelope to sweep the filter. Higher settings yield longer decay times.
Hi/Lo: This switch controls the range of the filter that is swept. Hi is thin and resonant. Lo is full and dark.

Mods
Try a pair of diodes with lower forward voltage for D1 and D2. This may improve sensitivity to picking dynamics. You can use 1n34a, BAT41 or BAT46.
Try a higher value pot for the Decay control for even longer decay times. Suggestions are 250kB or 500kB.


I can't find a vid of the Kraken and so here's the Mutron V.  I will swap this for a Kraken vid when someone here verifies this and posts one for me :o)

EHX Bassballs

Little something more for the bassists.. Should work nicely on guitar too.

Mad Professor Snow White Autowah

I did this as a bit of an experiment.  I want to build one and this has always been one of those that would prefer to do on a PCB, but I thought I'd still like to put a layout together to see how small I could get it using my methods and as I have I may as well put the results on here.

At 20 x 29 is may just fit in a 1590B if you aren't using a battery and have the stomp switch mounted right at the bottom, but with it having 4 pots, I think I'd probably opt for a 125B which should be a more comfortable fit.

Avoiding 19 links is another of the reasons why I would prefer a PCB :o)

Info about the great sounding original:

BJF design guitar and bass Auto Wah / Voltage Control Filter pedal

Hand-made in Finland premium quality auto wah pedal.

The SNOW WHITE AUTOWAH (SWAW) circuit is based on a 1991 BJF rack mount remote wah circuit and is tuned like a real wah.

The circuit was redesigned with envelope controls and built into small size pedal.

It has very fast tracking and accuracy rarely found on auto wahs/ envelope filters. With the four knobs you can have total control of the effect.

SWAW works both with guitar and bass and you can fine-tune the pedal to suit your instru-ment, your playing style and your taste of tone.

The pedal has a unique decay control for the filter frequency fall speed. You can set it to be fast for wah effects on every note, or slower for a more traditional auto wah sound.

Like all Mad Professor pedals SWAW is hand made in Finland using only premium compo-nents, to give years of trouble free operation with superb musical tone.

Controls

SENSITIVITY: Sets the filter trigger level, tune this carefully to fit your guitar/bass output and your playing touch.
You can further change the sensitivity from your guitar volume knob while playing.

BIAS: Controls the filter resonance frequency. When Sensitivity is turned fully off the Bias can be used as a sweepable filter.

RESONANCE: Controls the sharpness or Q-factor of the filter.

DECAY: Controls how fast the filter frequency falls back to resting point (that is set with the Bias control). This can be set fast (CW) so you get the wah effect on every note or slow for a more traditional auto wah sound.

PLAYING: Please take time to get used to the controls and as this is a voltage control filter it will react to your playing touch. The envelope control circuit is carefully designed to follow the dynamics of guitar/bass and it might take some time to master the Auto Wah playing technics.

Try also adjusting guitar volume between 8 and 10 to further expand use. 

Modded version as per the improvements discussed below in the comments:

eje Filter Mark 1

Here's a new one. Our user eje posted his filter design on the request section of the forum and asked us to draw a layout for it. The frequency graphs show that it cuts about 5db in 100-200hz range, peaks for +7db at ~2.5khz and cuts everything off from 500khz up. Cuts and boosts of 5-10db will make a difference, so this circuit may be very useful as addition to many dirt circuits - and why not just for getting a custom tone for your clean. I added polarity protection (1N5817 diode) and ripple filter caps for both, the main power supply and vref network. All the rest is eje's handwriting :) So here you guys go: