DIY Wah question

[oliphaunt]

I want to build a wah type of circuit for a specific purpose.  Instead a of a pedal controlled wah I want to make a "fixed wah" type of device, with a pot on the box to set the frequency.  Theoretically no problem.  I also want to add an input/output switcher to reverse the input and output jacks for the Pink Floyd "Echoes" seagull effect.   Theoretically no problem there either.

I have never build a wah circuit, so I checked out RG's Technology of the Wah article:
http://www.geofex.com/article_folders/wahpedl/wahped.htm

Very cool stuff, and since I don't have a true inductor lying around I tried his idea of using a Radio Shack transformer.  I breadboarded the basic wah circuit from RG's article using BC109, 5088 and 5089 transistors.  The end result with all transistors is that the wah actually works, but it doesn't sound very good.  It is very noisy, and the effect is working but not very musically pleasing.  I have troubleshooted the breadboard extensively.  Should I assume the main problem is the transformer, and that this will probably sort itself out with a correct inductor?

Also, this circuit will set up a whining tone (sine wave) when the input/output is reversed, but doesn't do the stuttering, "laughing" effect from Echoes when you adjust your tone control.  The ptch changes, but it does not stutter.  Hear that effect here:  

 I tested my other wahs to see if they do the stutter, and my 90s Vox will, but my old King Vox model 95-932011 does not "laugh, just creates a tone.  The King Vox has this inductor:


The 90s vox has what looks to me like the Dunlop inductor but with no markings:


Are these even critical for the sound I am looking to get?  The 90s Vox uses MPSA18 trannies, so I will try those as well, though I don't imagine there is much difference there.  King Vox has 5117.

Thanks for any advice.

[smallbearelec]

https://www.smallbearelec.com/Projects/WMouse/WMouse.html

See if the sound clips work for you.

[oliphaunt]

The clips sound good, but my primary focus on this circuit is the echoes effect. The fixed wah is sort of an afterthought to make the project more well-rounded.  I can't tell if that circuit will work well for me or not. It is interesting that you were able to get a decent sounding working circuit using the RadioShack inductor.  But, your circuit is different enough that I still can't be sure if that's my problem or not.

[dwmorrin]

As far as your noise problem goes, I wouldn't suspect the inductor.
What kind of noise are you talking about?  Can you be more specific?
Noise is usually generated by semiconductors and resistors, and gain stages will enhance whatever noise is present.

The oscillation frequency problem may be from your inductor's value in Henries being off.
Small bear had a cheap meter with an inductance tester... not sure if it's been restocked, but I it's fun to get quick inductance readings for wah circuits, checking pickups, etc.  You could do a scientific test with a meter, or you could buy inductors advertised with the correct mH for a vintage wah.

Also seems like the stuttering thing is tricky to execute even with the right wah, according to the video.

For parts I would stick with vintage circuit stuff. Use what Gilmour used.   Are you using a strat  with bridge and middle pickups?

[oliphaunt]

Thanks for the reply. The noise is a constant midtangey hiss, about half as loud as the guitar signal.  I have had issues with all of my Jfets going bad on me, but would not expect an issue with standard transistors. That is why I have tried so many.  I will continue to de-bug. 

As for the stuttering effect, yes I am using a strat, and the effect is quite easy to produce on my 90s Vox wah. The older Vox and the breadboard circuit produce a tone that changes pitch but does not have a stutter at any point in the travel of the tone pot. I guess I will try a few more production wahs and figure out what circuit works best, then try to duplicate it as closely as I can.  I would love to know though if I can expect a quality working wah using the radio shack transformer, just to know if I am doing something wrong or not.