Colorsound Inductorless; requesting suggestions

[arma61]

Hi all,

I've build the Colorsound Inductorless Wah, schematic : http://www.diystompboxes.com/smfforum/index.php?topic=66092.msg524660#msg524660

it sounds great, the only issue I have is about the volume; it seems I'm loosing part of it somewere. Is it normal for this kind of circuit? I've the following ideas to improve it.

- Decrease the 5M7 resistor on the base of Q1, any experience/ value suggested ?
- Play with values of caps, here I'm completely lost on which one I have to play, so again any experience/ value suggested ?.

I know I can "just give a try" to those ideas, but "expert opinions" are always better than attempts.

Thx
Armando

http://www.diystompboxes.com/smfforum/index.php?topic=66092.msg524660#msg524660

[soggybag]

I have been experimenting with Colorsound Wah and I used 3M3. The 2n2 and 6n8 caps in the T, can be made equal value, but I think I read somewhere this doesn't sound as good unequal values.

This wah sounds pretty good.

[foxfire]

i'm going purely off of memory but, i think what you want to do is to swap the 47k resistor to ground at the just in front of the output for a 100k or maybe 150k. start with the 100k.

[earthtonesaudio]

You could also try increasing the value of the resistors in the feedback loop (but that messes with the frequency), since they're effectively in parallel with the 5m7 resistor.  But higher values would mean more gain, not the other way around.  Increasing the load resistor to 100k or more as suggested is a good start, but a better way would be a buffer on the output.  Twin T wah's are prone to sound crappy when loaded down at the outputs.  For that matter, a buffer on the input might not be a bad idea either.  Simple JFET buffers only add 3 parts apiece, so it wouldn't make the build too much more complex.

[arma61]

I'm just playing with it now and

I have been experimenting with Colorsound Wah and I used 3M3. The 2n2 and 6n8 caps in the T, can be made equal value, but I think I read somewhere this doesn't sound as good unequal values.

thx, it improved a little bit could be even enough

This wah sounds pretty good.

I fully agree!

i'm going purely off of memory but, i think what you want to do is to swap the 47k resistor to ground at the just in front of the output for a 100k or maybe 150k. start with the 100k.

thx, yes I saw that on some file with PCB layout, and by feeling, I already put a 100k in there.

You could also try increasing the value of the resistors in the feedback loop (but that messes with the frequency), since they're effectively in parallel with the 5m7 resistor.  But higher values would mean more gain, not the other way around.  Increasing the load resistor to 100k or more as suggested is a good start, but a better way would be a buffer on the output.  Twin T wah's are prone to sound crappy when loaded down at the outputs.  For that matter, a buffer on the input might not be a bad idea either.  Simple JFET buffers only add 3 parts apiece, so it wouldn't make the build too much more complex.

thx, that's maybe what I've found after the few tries above, I've soldered a 33k in parallel with the 330k (is this what you mean ?), and got a loads of volume, I'm testing  with a radio signal at the moment, as soon as I've cleared and cleaned my working desk I'll take out my axe and test it with this configuration

still missing to test changing caps, but I like as it is now, frequency wise, so that will be last chance.

By the way if you wanna look at http://www.diystompboxes.com/smfforum/index.php?topic=66424.msg527785#msg527785, this is my testing equipment! ah ah ah ah  it works, not handy, but works

cheers

[John Lyons]

Careful with the input resistor getting too low as the distortion creeps up a bit. Especially since this design as all Twin T circuit is a little dirty in the first place. For distorted sounds it's no problem but for very clean sounds is gets a little harsh.
Which transistor are you using? The transistor makes a lot of difference with the gain output since there is only one.
I'd try a 2n5089 or BC109.
Put a 50K pot in in place of the 33K to ground. Instant resonance control, can get wild if you want self oscillation!! or dial it back.

john

[arma61]

Careful with the input resistor getting too low as the distortion creeps up a bit.

I've lost part of the "sweep" of the pot, could be the above the reason ?

Better I leave it as it was supposed to be, and just play, as you suggest, with tansistor gain, I think I've a 5088 in there, will try with a BC109

what about a mosfet booster in front ?

Thx

[Dragonfly]

why not just put a single stage booster AFTER the wah circuit ? Seems like a simple enough solutiion.

[arma61]

something like the AMZ Mosfet Booset ?

thx

[Dragonfly]

something like the AMZ Mosfet Booset ?

thx

you wont need that much boost...

something like the Tillman, the Sparkle Boost, Stratoblaster, a LPB, etc will give you more than enough...The Tillman is about a 3dB boost, the others will give you more...

[arma61]

ok I should have a Stratoblaster somewhere I'll give a try

Thanks Dragonfly

[fuzzo]

I've did the inductorless and I've the same problem.

I've you found a solution ?

[arma61]

I've solved this issue with a boost in front of the wha, it works, even too much, pot is alway at 10-20%, otherwise it start to distort.

I cannot remember which kind of boost it was, I think I took it from other schem, it use 1 caps 4 res 1 pot and a 2n5088


I have ExpressSCH and ExpressPCB file if you want them, they're tested, I've used here




Ciao
Armando

[fuzzo]

Ok thanks,

actually , I'm doing a  pedal similar to The dunlop Q zone, i'll put a circuit to add some grit to the wha sound.
But the inductorless alone , I can feel the volume is reduced.