Highway 89 mod I did. Why/how does it work?

[Morocotopo]

Hi, I made the Highway 89, great sounding pedal. I used BC549´s. Cool fuzz / dist, cleans up nicely from the guitar vol control.
I found that with the level pot 1/4 of the way up, it´s plenty loud, so the rest of the travel is not very useful (at least for me). So I tried to reduce the output, first with different value level pots (higher, lower), but that didn´t work. Finally i put a 470K resistor in the output, from the middle level pot lug to the output wire. that did the trick, and also it reduced the highs slightly, wich for me was a good thing. Now I get at 1/2 the pot travel the same level that I got at 1/4 before.

Schem:
                         POT (500K log)
                      1   2   3
                      /    |    \
---circuit out---     R     GND
                           |
                         OUT

The question(s) are:
1 - Why the resistor reduced the highs and not just the level?
2 -Does it change the output impedance in some (bad) way, that I should be aware of (eg, affecting the following pedals/amp, increasing noise, etc.)?

thanks for reading

Morocotopo

[Barcode80]

more resistance, as i understand it, raises the impedance of the signal and thus trims sime high end. (if i understand impedance correctly, which it is likely that i don't) a higher frequencies have a harder time travelling through i high impedance signal. this is why when you use a cheap XLR -> 1/4" mic cable which takes the low impedance mic signal and crams it through a high impedance cable, you lose a lot of your high end.

i'm positive i just butchered the tech explanation of this, but someone with more experience might be clearer.

[John Lyons]

I noticed this as well. I would think that making the level pot 100k would be fine. Haven't tried it yet though.
You don't want to raise the impedance though... so that 470 at the wiper isn't the best thing to do.

John

[MartyMart]

Wouldn't a better way be to "bleed" off signal before the pot, with perhaps a 220k
to ground ?
P-90's and the like, without volume knobs do this to get "unity" gain to bypassed level ...

MM

[Morocotopo]

Thanks for the answers. Marty, never thought of that, haven´t seen that idea before (limited knowledge). Will try.

Morocotopo

[snoof]

and if you want to lose some high end, put a RC filter to ground before the output pot.