escobedo's PWM concerns

[choklitlove]

i have built this circuit using my own layout here:
http://geocities.com/worthekik/pulsewave.html

i was really excited because it works and it sounds really good.  however, upon going back to the snippets site and listening to the sample (http://users.adelphia.net/~tpe123/pwm.mp3), i realized mine sounds different.  the difference is that mine doesn't "wave" or pulsate.  the "width" pot on mine still works, but i'm guessing it's not doing all that it's supposed to.  it makes the sound thicker and bassier, and maybe even fuzzier.  i almost like the sound of mine better, but i'd like to know what happened.  is there something wrong with my layout causing this to happen?  is there some part of one of the ics that isn't being triggered?

thanks!


this is the schematic:
   

[jrc4558]

sorry, but did you add the oscillator? the EZ LFO?

[choklitlove]

no, but if tim's sample has it...

that would explain it.

[Jamforthelamb]

I've built this with the LFO, and it sounds exactly like Tim's sample, so I'm sure that's what your missing.

It definitely sounds cool, but I would like to hear it with a ramp up/down. With the LFO the change is almost instantaneous, it would be cool if you could make it gradual like a phaser. I know Tim was just using the un-used pins on the chip, and trying to keep it from being over-complicated, and I absolutely adore the pedal, so don't get me wrong.

God Bless,
JFTL

[choklitlove]

thanks you guys.  i feel better knowing mine's okay.  i really like the pedal.  if i decided to add the lfo, i would have put in a switch as well to turn in on because i like the way it sounds without it so much.

nice circuit tim.

[mongo]

must be fun tu put the atari punk console thru this one.


Andy

[any]

If I may do a bit of thread hi-jacking... 

I've also built the PWM into an old crybaby shell with the "pulse width" pot on the treadle.
It sounds extremely cool on bass guitar. (a bit like deeper underground by Jamiroquai)
The problem is I built it without a master volume so it was extremely loud.
I went to built in the master volume but then something weird happened,
when I turned down the volume it also turned down the bass.
It was almost like putting the pulsewidth to it's thinnest setting.
After that I built in a simple IC buffer after the output and before the volume pot,
however now even a volume pot with a value of 1k isn't small enough to provide a good
taper since only the first 10% of the 1k pot attenuates.
Would anyone know how to reduce the buffers gain to actually reduce gain? (-4dB)
or some other solution to keep the PWM sound but turn down the volume...

[jrc4558]

use a 10uF output capcitor

[any]

use a 10uF output capcitor

will this retain the bass if I use a passive volume control, or will it change the behaviour
of the pot taper when I use an IC buffer after the output?
(sorry if this sounds dumb, I suspect the first but I'm interested in what it does too...  )

[nordine]

I would like to hear it with a ramp up/down. With the LFO the change is almost instantaneous, it would be cool if you could make it gradual like a phaser.

if you take the LFO from pin 13, it would get more triangle wave-ish