BAJA Kiwi Merry Christmas Wah Wah pedal 221219

bajaman · Post by **bajaman** » 22 Dec 2019, 06:02

Hi Folks
Merry Christmas to all

Here is a little something that i have been working on for some time - it is very low noise, extremely easy to customise and it does not use an inductor.
I built mine on a piece of stripboard - I may design a pcb for this in the new year. I used a OPA4134 quad opamp but a TL074 or two TL072 opamps should work fine - the choice is yours

I have suggested components that can be altered to zoom in on your favourite wah response. (I am currently very happy with 1820pf for C14 and 2.5nf for C3 - I paralleled 1nf capacitors across the existing value capacitors - go ahead and experiment, i am sure you will find your "perfect" wah with this circuit.
cheers

bajaman

Chugs · Post by **Chugs** » 22 Dec 2019, 09:59

Nice, I like that it is buffered bypass as you could easily retrofit it into an existing wah enclosure and use the SPDT footswitch that most have.

Is the Q response constant or does it vary with the sweep like an inductor wah?

bajaman · Post by **bajaman** » 22 Dec 2019, 10:10

Chugs wrote:Nice, I like the it is buffered bypass as you could easily retrofit it into an existing wah enclosure and use the SPDT footswitch that most have.

Is the Q response constant or does it vary with the sweep like an inductor wah?

The Q varies with the sweep exactly the same as the inductor wah

cheers
bajaman

bajaman · Post by **bajaman** » 23 Dec 2019, 01:52

update: installed two 6 position rotary switches for C14 and C3 and fitted 6 capacitors to each
C14: 820p, 1n, 1n2, 1n5, 1n8, 2n2 (frequency high to low)
C3: 1n5, 1n8, 2n2, 2n7, 3n3, 3n9 (Q high to low)
gives some nice variations

cheers
bajaman

Chugs · Post by **Chugs** » 23 Dec 2019, 13:35

Loads of variation!

Any suggestion for a value for C3 to approximate the Q of a 33k resistor in parallel with an inductor?

bajaman · Post by **bajaman** » 23 Dec 2019, 21:13

Chugs wrote:Loads of variation!

Any suggestion for a value for C3 to approximate the Q of a 33k resistor in parallel with an inductor?

Well I simulated the Vox wah with the inductor and 33k and it is pretty damn close with C3 at 1.5n

I know some folks like to increase the Q for a more "vocal" sound by changing the 33k to 100k - Reducing C3 to 1n will have a similar effect on the Q

cheers
bajaman

bajaman · Post by **bajaman** » 25 Dec 2019, 22:03

update #2
I changed the 6 position switch capacitors slightly to allow for some higher Q settings.
C3 is now: 820p, 1n, 1n2, 1n5, 1n8, 2n2 - the same as the frequency sweep capacitors.
I have found that the balance between wah wah and bypass is good for me but if you would like to increase the wah level, then decrease R35 (try 4k7 for example). However this will change the sweep frequency so to retain the same frequency but with higher output level decrease C14 by the same proportion (try 390p if using 4k7 for R35). You can also decrease the wah level with respect to the bypass level by increasing R35 and C14 - (try 15k and 1n2 for example)

In the two examples given you should see a 9db increase in level or 3db decrease in level approximately - the Q and sweep range should not be affected to any great extent by these changes - just the output level

All the best for Christmas to all who dwell here and i do hope some of you try this wah wah build - you will be pleasantly surprised at how it sounds - all the best - Peace and Love
bajaman

rcustoms · Post by **rcustoms** » 26 Dec 2019, 03:14

bajaman wrote:update #2
I changed the 6 position switch capacitors slightly to allow for some higher Q settings.
C3 is now: 820p, 1n, 1n2, 1n5, 1n8, 2n2 - the same as the frequency sweep capacitors.
I have found that the balance between wah wah and bypass is good for me but if you would like to increase the wah level, then decrease R35 (try 4k7 for example). However this will change the sweep frequency so to retain the same frequency but with higher output level decrease C14 by the same proportion (try 390p if using 4k7 for R35). You can also decrease the wah level with respect to the bypass level by increasing R35 and C14 - (try 15k and 1n2 for example)
In the two examples given you should see a 9db increase in level or 3db decrease in level approximately - the Q and sweep range should not be affected to any great extent by these changes - just the output level
All the best for Christmas to all who dwell here and i do hope some of you try this wah wah build - you will be pleasantly surprised at how it sounds - all the best - Peace and Love
bajaman

you could add an optical system like morley wah

mictester · Post by **mictester** » 26 Dec 2019, 20:22

I tried something a bit like this using a state-variable filter, with highpass, bandpass and lowpass outputs. I used an LED to illuminate an LDR with two polarised filters - one fixed, and the other rotating with the pedal position. I couldn'y ever get the response I wanted.... I'm going to try your circuit and see if I can get it sounding right! Thanks for another great design idea.

bajaman · Post by **bajaman** » 27 Dec 2019, 00:32

Here is a pcb design that will retrofit a standard wah pedal enclosure - the WAH OUT goes to one side of the footswitch and the BYP goes to the other side - the output socket is then connected to the common terminal of the footswitch. I should have some boards available early in the New Year - if you would like to order one or more please send me a PM - thanks
bajaman

Baja Kiwi Merry Christmas Wah Wah 221219.zip: (13.71 KiB) Downloaded 148 times

bajaman · Post by **bajaman** » 29 Dec 2019, 10:21

Sorry - the gerber zip file I posted was not complete - here is the corrected one

bajaman

Baja Kiwi Merry Christmas Wah Wah 221219.zip: (14.07 KiB) Downloaded 203 times

bajaman · Post by **bajaman** » 17 Jan 2020, 06:19

The boards arrived today - pm me if you want to purchase one or more.
cheers
bajaman

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TimMikhailouski · Post by **TimMikhailouski** » 13 Jul 2020, 13:49

Awesome schematic! Works with guitar wery well!

What modifications would you advice to make this pedal bass-friendly?

TheGunn · Post by **TheGunn** » 11 Feb 2023, 16:35

There's unverified veroboard layout for this project.
EDIT:
There was a mistake with left jumper next to 10k resistor. Now layout is corrected. Also I realized that it can be one column smaller, than previous one.

TheGunn · Post by **TheGunn** » 25 Feb 2023, 17:28

Updated layout (corrected cut in right bottom corner of a board).

BAJA Kiwi Merry Christmas Wah Wah pedal 221219 [documentation]