Noob question about stepped attenuators

[Paul Birkeland]

It drops the impedance a bit.

 

[ohshitgorillas]

I used an alligator clip between the two 50k resistors. I hooked them up on the switch side of the resistors. It didn't do really anything to spread out the volume control but nuked the bass. I tried hooking it up to the signal side of the resistors, but of course this just mixed things down into mono and also did nothing to improve the spread of volume control.

 

[ohshitgorillas]

I am also wondering if there is a good website you know of or a way for a newbie like myself to mathematically understand the relationship between gain and load, and also between resistance and gain e.g. if I wanted to do a 100k pot with 0, -12, and -24 dB, how would I go about selecting resistances to match those gain values and how would I go about selecting

Parts of the schematic you drew me made sense. The resistance increasing from 50k to 75k to 94k as gain increases is easy to follow. But why does this add a small amount of resistance to low gain, a higher amount to medium gain, and none to low gain? This part makes no sense to me.

I want to understand, and it seems relatively simple, but obviously I'm missing some basics.

 

[diynewbie]

I'm also watching this with interest.

Your posts reads like you ran a wire from the left to right channel on each side of the switch.  I believe the suggestion was to by-pass the 50k resistor on each channel - i.e a connect a wire from the input side of the 50k resistor to between the 50k and 25k resistors.  Is that what you did?

 

[ohshitgorillas]

That makes so much more sense... I will try that tonight

 

[Paul Birkeland]

I am also wondering if there is a good website you know of or a way for a newbie like myself to mathematically understand the relationship between gain and load, and also between resistance and gain e.g. if I wanted to do a 100k pot with 0, -12, and -24 dB, how would I go about selecting resistances to match those gain values and how would I go about selecting

You'll have to read up on Ohm's Law and how parallel and series resistors work, then look up the formula for calculating attenuation based on voltage division (in this case resistance can be used as a direct substitute).

-PB