Ugly Face Mix mod

[soggybag]

I want add a mix control between the output of the 389 and the out of the 555 in the Ugly Face. I have been thinking about this for a while and have finally gotten around to giving it a try.

Comments and sugesstions gladly accepted. I'm sure there's something I'm missing.

[soggybag]

I tested this out with the values listed in the image and it seems to work well, though there seems to be a small loss of volume when the mix knob is centered.

I would recommend this to anyone who built an Ugly Face. The mix knob allows the regular guitar sound back into the signal which adds some bass and can remove some of the hard mechanical sound of the straight Ugly Face.

I'm open to comments if anyone sees anything obvious that could be added or missing or could be improved upon.

[Processaurus]

How about the typical mixer section, with the 4 resistors and pot with the wiper to ground, like the blend knob on the MXR blue box?  Then theres no interaction, and and an even transition as the knob gets turned.  Theres so much signal available with the ugly face (~8v p-p), it could see to be knocked down by a factor of 5 and still have plenty of output (~1.6v p-p).  A bigger resistor (relative to the 3 others in the classic panning circuit) between the 555 and the outer lug of the blend pot could be made larger to attenuate the uglyface relative to the clean signal from the 386, if it turned out the mix was lopsided when the knob was centered.

But if you're happy with how sounds, no need to "fix" it.

[Tim Escobedo]

You could probably get away with using a smaller value mix pot (I'd try 1k to 10k) and larger value coupling caps for less volume loss in the center position. I think the output impedance of the 7555 is pretty low, should work OK.

[soggybag]

Thanks for the replies.

I'll give the 10k pot a try, and change the .1 cap to 2.2 in the mixer so the caps are euqal. This seems to be the easiest and simplest solution.

I might give the Bluebox mixer a try. It seems to have a few more parts but does not look too complex. I wonder about C9 and C10, on the Tonepad schematic, I would expect a single coupling cap here?

I think the mix adds a lot to this effect. The only problem is with the number of knobs. Adding the mix adds a fifth knob, which is hard to plan around. I have been thinking to replace threshold with a switch. It seems that this control, in this effect, is either on or off.

[soggybag]

I chnaged the mix pot to 10K and both of the caps leading to it to 1u. This seems to work pretty well. I updated the schematic above also.

I think the next change is to change the threshold pot to a switch as it seems that it is either on or off anyway.

[idiot savant]

here's another similar way from awhile back.

http://www.freewebs.com/fkstilt/uglyfacemod.htm

[soggybag]

That's very similar. I'm not sure what the switch is doing?