Yellow Humper built

[RickL]

Since the schematic for this surfaced a short time ago I thought I would give it a try. I built it using a modified Pico Morado (Purple Peaker) layout from Tonepad with 2N3904's for the transistors and negative ground. It fired up right away and sounds about like you'd expect it to, like a Purple Peaker with the two frequency boost shifted down a bit. The lowere one gives a nice bass boost and the upper one adds some bite (upper mids?).

If you look at the schematic you'll notice that unlike the Purple Peaker the two switches don't short the whole resistance at the bottom to ground, just most of it. I ended up using spdt centre-off switches so I could short either just the 470k resistors or the whole 470k/15k or 470k/33k combination. Shorting the extra resistance gives either a bigger bass boost or a more noticable mid (?) boost.

Another option would be to replace the two resistor combos with a 500k or maybe 1M pots or even a 390k or so resistor in series with a 50k or 100k pot. I like the simplicity of the three position switches.

I don't remember exactly where the schematic is but I think a search for Musitronics on the forum will find it.

Rick

[ragtime8922]

this is a bass EQ, right? I'll bet it would work nicely for a guitar rig that needs a low end boost. Might need some slight tweaking and a bit of math to get the frequencies right OR you can make the filters adjustable for a parametric application. Then you'd have a purple peaker, yellow humper, MR. EQ and countless others in one box.

[Fp-www.Tonepad.com]

Cool. I have yet to upload that project. Since the layout is the same as the peaker it shouldn't be too long before I do.

Fp