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DIY Stompboxes => Building your own stompbox => Topic started by: bobbletrox on March 08, 2004, 09:47:24 PM

Title: 3 Legged Dog >> Double D Bounce?
Post by: bobbletrox on March 08, 2004, 09:47:24 PM
(http://users.bigpond.net.au/styrowfoam/schem.gif)

I really like the sound of the bounce channel in the Double D from Runoffgroove.com, so I was thinkin' the 3 Legged Dog could be modified to be a stand-alone uh...Single D?  Anyhow, I drew up the above schematic that combines the feedback loops from the DD and the single jfet input stage from the 3LD...but I've got a few questions:

a) the 3LD has resistors to ground on the first two inverters while the Bounce channel only has one on the first inverter -what difference does it make?
b) the DD has a further two .22uF caps before the output which I figure need to be taken into consideration if I wanna get that bounce tone -so do I need to replace the 4.7uF output cap with something like a 1uF to approximate the effect those smaller output caps have on the tone?

Thanks  :o
Title: 3 Legged Dog >> Double D Bounce?
Post by: B Tremblay on March 09, 2004, 07:40:08 AM
In response to your questions:

A.  Not much at all.

B.  They actually have the same output cap.  Before the volume pot of the Bounce channel, there's a 4u7 cap.  Due to the channel switching, the output buffer needs an input cap to prevent a volume control from being in parallel with the gate resistor.  If you are building a single channel of D, then you can just take the output from the wiper of the volume pot as usual, omitting the output buffer.
Title: 3 Legged Dog >> Double D Bounce?
Post by: Lurco on March 09, 2004, 08:03:32 AM
Why is there an input FET, when those inverters themselves have high input impedances?
Title: 3 Legged Dog >> Double D Bounce?
Post by: B Tremblay on March 09, 2004, 08:14:05 AM
It's there as a gain stage, not as a buffer.
Title: 3 Legged Dog >> Double D Bounce?
Post by: bobbletrox on March 09, 2004, 08:24:41 AM
Quote from: B TremblayIn response to your questions:

Ahh great!  Thanks for answering my questions!  I can't wait to hear this circuit for myself.

:o

*EDIT*  So the schematic I posted is good to go?
Title: 3 Legged Dog >> Double D Bounce?
Post by: smoguzbenjamin on March 09, 2004, 08:28:12 AM
B why did you include two pots for each channel? Is it out of a technicality or just because it's useful to set the two stages independently?
Title: 3 Legged Dog >> Double D Bounce?
Post by: Lurco on March 09, 2004, 08:32:24 AM
Quote from: B TremblayIt's there as a gain stage, not as a buffer.

ooops, yes, sorry for that stupid question; I seem to have not looked close enough. Thank you!
Title: 3 Legged Dog >> Double D Bounce?
Post by: B Tremblay on March 09, 2004, 09:06:22 AM
Quote from: smoguzbenjaminbecause it's useful to set the two stages independently?

Yes.
Title: 3 Legged Dog >> Double D Bounce?
Post by: smoguzbenjamin on March 09, 2004, 09:08:01 AM
Cool thanks. That's one of the best DIY distortions I've heard if the samples are accurate. It sounds pretty amp-ey. I have a 4049 lying around, I think I'll build this... Maybe even use it as the distortion channel of my own amp! :mrgreen:
Title: 3 Legged Dog >> Double D Bounce?
Post by: B Tremblay on March 09, 2004, 09:15:04 AM
Quote from: bobbletroxSo the schematic I posted is good to go?

Well, you might want a Gain control.  There's really no need to turn the 3 Legged Dog into the Bounce channel, just use the Bounce section without the channel switching or output buffer.

Here's what I suggest: working from the Double D schematic, connect lug 3 of the Bounce Gain pot to the output cap of the FET stage.  Omit the output buffer as I described before.  Of course, the entire Jiggle channel is removed as well.
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