distortion+

[dazzlindino]

Was wanting to know if anyone has had any luck with modding these pedals to really add distortion, seems to my ear that it may add a little but really is more of a booster.
Any another thought is what would someone in the 70s have done to one of these pedals to add distortion to it? Thanks

[Liam]

Some suggested mods. When you say "adding distortion", do you mean more gain. You could also reduce the value of the 1M feedback resistor in the op amp feedback loop to get it to drive the clipping diodes harder. Might get noisy though.

http://www.schematicheaven.com/effec..._dist_plus.pdf

Liam

[Mark Hammer]

Actually, the reverse. You need to increase the value of the 1M feedback resistor to increase gain.

The stock Dist+ has a .047uf cap in series with the Gain control. One of the side-effects of that is that bass gets trimmed as you crank the gain. While that helps to increase the perceived bite, and also reduces the risk of 60-cycle hum becoming truly annoying, it also reduces the apparent drive and distortion. A big chunk of the signal "lives" below 500hz and the bass rolloff at max gain starts around 720hz. If you replace the .047uf cap with a .22uf value, you will probably hear a little more of what you seek. Also consider reducing the 4.7k resistor in series with the Distortion/gain control to 3.3k or even 2.7k for greater maximum gain.

[Liam]

Actually, the reverse. You need to increase the value of the 1M feedback resistor to increase gain.

DOH! Can't believe I just did that... Yes, Mark is quite correct.

[Modded D+]

Here is just a simple mod you can do for fun. I added a switch to toggle between diodes - Silicon/Germanium. To be honest, there isn't a huge difference. I might swap one side out for LEDs.

[Mark Hammer]

When the original was produced, it would seem that part of the intention was to be a combination booster and distortion. As a result, the "Distortion" control ranges from what is basically clean boost up into the distortion range. The reason why the unit needs to use a 1M reverse log pot is so that:
a) the user can very quickly get past the lower 90% of resistance (you don't start to get any appreciable bite until you hit the 50k mark)
b) the pot can be wired up to provide more gain in a clockwise direction; a person could easily use a normal (rather than reverse) log pot if they were willing to have the gain reduced while turning clockwise.

When I make them, I skip the 1M reverse-log, and go directly to a 100k or 50k pot, since I don't particularly need the pedal to be a clean booster for me.

I did the Si/Ge mod and find that it makes a substantial difference, especially with respect to output level. The Si diodes will provide approximately double the maximum output level.

[Nate]

When I was a kid I wound a homemade soundhole pickup (which I actually found recently - it still works) using radioshack rectangular ceramic magnets (I recall it was very difficult to tape them together with the poles all facing the same way.) The output was so low, I actually used a Distortion+ pedal as a preamp. On my electric guitars there was plenty of fuzz to be had though.