Is there a Twin-T style wah that uses a single opamp?

[Derringer]

maybe someone has adapted the colorsound inductorless to work with an IC ?

[frequencycentral]

Essentially a Dr Q / Nurse Quacky with a treadle instead of a follower. As used here (but without the noise generator):

http://www.diystompboxes.com/smfforum/index.php?topic=81602.0

[Derringer]

cool Rick, thanks

that's much simpler than I thought


I'm trying to put put together something ridiculous for my bassplayer inside of a wah shell

going to attempt combining an octave up section with a wah section

[Derringer]

http://www.zshare.net/audio/74330456bd4d0a6c/

keep in mind, I play guitar ... not bass   And most of this nonsense in the clip is being fed into a big muff, I'll make some better clips tomorrow when everyone else in my house isn't trying to sleep.
that's a bassballs towards the end of the clip too .. just to see what would happen

Can I get a more dramatic HHHWWWAAAAHHHH out of it?

I did play around with the caps a bit but 4700 pf on both sides still sounds the best right now


The design is based around a TL074

the clean signal starts into a single pole Low Pass filter with a corner Q at 160Hz and lots of gain (100)
then into a two stage rectifier that i got from here:
http://sound.westhost.com/appnotes/an001.htm
more specifically, this one
http://sound.westhost.com/appnotes/an001-f6.gif , it's been modified to operate on a single polarity voltage
then into the wah stage that you posted

any and all insight is appreciated

Thanks!

[azrael]

Joe Gagan's Freeper?

http://aronnelson.com/gallery/main.php/v/album72/28GaganFreeperDirty.mp3.html

Not IC based, but i believe its a Twin T style circuit.

[frequencycentral]

Sounds very cool! For more dramatic HHHWWWAAAAHHHH you might try looking at ROG's Phozer for some ideas, it have two parallel stages tuned slighly apart as well as the addition of resonance.

http://www.runoffgroove.com/phozer.html

[earthtonesaudio]

Essentially a Dr Q / Nurse Quacky with a treadle instead of a follower. As used here (but without the noise generator):

http://www.diystompboxes.com/smfforum/index.php?topic=81602.0

Note that the Dr Q has the option of twin-T or multiple-feedback filter configurations.  And if you're a little creative you can implement both simultaneously.

[Derringer]

http://www.zshare.net/audio/7435397073c593cf/

here it is with a variable resonance added ala phozer-style ..... thanks for the tip!

in the clip I'm playing with different combinations of clean and fuzz post the wah


I'm using a 250K pot wired as a VR and a 10K resistor going into the inverting input of the Twin-T opamp section as a volume control.
Is that bad practice? I'd like to have some adjust available for volume.

I haven't tried it, but I figured if I used a VR in the feedback loop of the filter then I'd be effecting the filtering characteristics when I altered the volume.


Thanks for all the great ideas folks!

[amptramp]

Some good info here:

http://www.geofex.com/Article_Folders/wahpedl/wahped.htm