Walco Effects - Schematics for the fuzz generator and others inside...

[markm]

 
I was just applying "Keen's Law"!
Guess it works!
Thanks again for the info, I appreciate it.
You say you have several of these.....care to part with one of the sustainers??

[zachomega]

I have several, but they all have bad switches except for 2.  Barcode80 indicated that he is interested in the lot of them that I have, but if it is okay with him, I'd pull one out of the lot for you, but you'd have to ask him. 

-Zach Omega

I was just applying "Keen's Law"!
Guess it works!
Thanks again for the info, I appreciate it.
You say you have several of these.....care to part with one of the sustainers??

[markm]

Okay,
I PM'd him. 

[Doug_H]

Modifying the time constant would be simple if there was room on the board for additional parts or room in the box for a pot.

I would think it would just be a matter of swapping out an existing cap in the detector/rectifier circuit.

I wonder if this effect would be more useable if the volume on the guitar were turned way down.  Most guitars in the 70's didn't have the same kind of output that modern guitars have now.  On top of that, most Japanese guitars have very low outputs.  Think Teisco Del Ray. 

That's a good idea but IIRC I think I tried that and it didn't help much.

I think it is quite obvious that I've spent a bit too much time with these units. 

Me too, and I think I only spent 20 minutes with it.

Heh-heh! My reason for buying it was to a) help my wife pump up her ebay feedback by using her acct, and b) just to satisfy my curiosity.

My curiosity is satisfied. It's basically a piece of junk AFAIC. Even if you do mod it into something that sounds reasonable, it's still a p.o.s. box and a p.o.s switch, at most. It's not worth my time to mess around with for that. I think I'd rather breadboard stuff and build what I like than mod something that is still going to be a piece of junk.

[Meanderthal]

 Aw, c'mon now, I kinda like that wierd little enclosure. I cracked up the first time I saw that switch though... never saw anything quite like it besides those cheezy rat shack momentary switches. Mine works just fine for now, but I sure don't trust it. Not that I ...use it or anything, It gets most use as a joke kinda thing-"hey, wanna try out this 'vintage' compressor I got?" And watch the look they get when they hit the switch and that horrible clamping kicks in followed by the even more horrible roar of noise... hilarious! I've done that twice now, and messed with it myself really only once.
I'd love to see these get... 'fixed'. If there was ever a pedal that absolutely MUST be modded, this is it, and to me there would be a kind of appeal in turning something so inherently bad into something good.
Yeah, I know that sounds ridiculous, like the guy with the hot-rod Pinto... They say you can't polish a turd... but you CAN put perfume on a pig!

[Antero]

And lipstick.

The idea of beyond-insane compression interests me, so I'd totally be interested if there was a way to remove the suck.

[zachomega]

Well, as I mentioned, subbing the 3sk30 for a 2n5457 eliminated the noise problem. 

That pretty much leaves just the ridiculous compression.  Changing the 33uf cap would definitely help.  If you could find a place to install a series resistor after the detector diode and before the cap, that'd probably help a lot as well...and perhaps a high value shunt resistor with the cap. 

On the other hand, lowering the 33uf cap will probably cause a bit of warble in the signal depending on how sensitive the 2sc644 is. 

-Zach Omega

[Eb7+9]

seems to me the input resistor was made way large because the output has so much post-gain build-up - one poor choice to overcome another perhaps ... in voltage-divider based compressor circuits one really only needs as much gain to compensate for losses in the divider network, or maybe just a little more ... 

I'm assuming there's enough gain in the first gain stage to make-up for signal loss in the voltage divider made up of the input resistor and variable resistance (transistor) in which case the input resistor doesn't need to be so large after all ... the gain buildup following this first stage is mostly necessary for driving the detector circuit and not, in principle, for providing enough signal output ...



one nice thing about moving the output feed to the front in this circuit is that it would allow for inclusion of a threshold control - by making one of the make-up collector loads variable ... one could parallel a 25k pot across the 4k7 load instead of replacing by 5k pot ...

also, the input resistor is killing so much signal, making it variable will allow for tailoring of response (RATIO) and cause less sucking ... a 1Meg or 2Meg pot should work ... this needs to be changed if the output feed is taken earlier anyway ... both are intercoupled ...

changing the noisy transistor by a low noise jFET is definitely a good idea ... the long release time can be reduced to a more common 1uF value for this kind of detector but as mentioned this will likely cause some bouncing so a PI filter as drawn can be used to help stabilize ... see my PAIA nfinity+ re-design, it uses similar detector filter arrangement and values ...

JC

[tcobretti]

Nice mods Eb7+9!  I may have to breadboard this one.  A nice super simple guitar compressor is always welcome.

[zachomega]

If somebody tests this circuit, PLEASE let me know the results.  With some careful work, I'll bet most of those mods could be performed on the existing circuit board. 

-Zach Omega

seems to me the input resistor was made way large because the output has so much post-gain build-up - one poor choice to overcome another perhaps ... in voltage-divider based compressor circuits one really only needs as much gain to compensate for losses in the divider network, or maybe just a little more ... 

I'm assuming there's enough gain in the first gain stage to make-up for signal loss in the voltage divider made up of the input resistor and variable resistance (transistor) in which case the input resistor doesn't need to be so large after all ... the gain buildup following this first stage is mostly necessary for driving the detector circuit and not, in principle, for providing enough signal output ...



one nice thing about moving the output feed to the front in this circuit is that it would allow for inclusion of a threshold control - by making one of the make-up collector loads variable ... one could parallel a 25k pot across the 4k7 load instead of replacing by 5k pot ...

also, the input resistor is killing so much signal, making it variable will allow for tailoring of response (RATIO) and cause less sucking ... a 1Meg or 2Meg pot should work ... this needs to be changed if the output feed is taken earlier anyway ... both are intercoupled ...

changing the noisy transistor by a low noise jFET is definitely a good idea ... the long release time can be reduced to a more common 1uF value for this kind of detector but as mentioned this will likely cause some bouncing so a PI filter as drawn can be used to help stabilize ... see my PAIA nfinity+ re-design, it uses similar detector filter arrangement and values ...

JC

[markm]

I'm working on a Layout for the Modified Version posted above and hope to have results in the near future.
I just added the Original circuit to my gallery for those interested.
You can find it right this way>>>>>>http://aronnelson.com/gallery/MarkMs-Gallery

[zachomega]

I definitely want to know how this turns out.

Also, the link isn't working for me.  Is it just my ISP or is it just not working for everybody?

-Zach Omega

I'm working on a Layout for the Modified Version posted above and hope to have results in the near future.
I just added the Original circuit to my gallery for those interested.
You can find it right this way>>>>>>http://aronnelson.com/gallery/MarkMs-Gallery

[markm]

I think the gallery is down right now.
Incidently, I subbed the 1M pot for the 1.5M resistor on the front of the circuit and it added some control but, caused distortion as well.
Keep in mind this is still with out the other mods but, the distortion wasn't major but very noticable.