treble bleed circuit (increase volume)

[effectsbay]

Hello

Trying to add a simple treble bleed circuit to my pedal. Added a .001uF film cap and 100k resistor to 1M audio pot with SPST toggle. Problem is that when the circuit is engaged, I get increased signal volume? I was surprised by this? Any ideas as to why?

Thanks!
hank

[John Lyons]

More volume when the volume pot is turn all the way up of more volume when turned about half?
Since the pot is so large in value, when you turn the pot half way down you have 500K series resistance
that gets bypassed which makes a big high pass/treble boost/treble bleed. Granted you have the 100k in
series as well...
Is the sound/tone right to your ears?
Try a smaller cap if it's too bright...
or a larger resistor.\for more of a shelf response.

[effectsbay]

Hello

Thanks for the reply! More volume if the pot is halfway rolled off... by a significant amount. Tone sounds good with the .001uF/100k resistor. Hella bright without the resistor. So by adding a 1MB resistor there I should be back to 500K? so .001uF and 1M in parallel??

Thanks!
hank

[John Lyons]

I would try a smaller cap. Generally the sets the frequency and the resistor
limits the amount that the cap passes treble through, in relation to the pots volume
roll off.

Using a 1M resistor is going to be too big I think.
I would select a cap by itself and then a resistor to limit
the amount of treble you get when rolled off.

You don't NEED the resistor so you may want to try a cap
by itself an see what you get. Try 150p and up to start.

[GibsonGM]

You don't even need the resistor with the cap....it just makes the transition smoother. I leave them out of my guitar treble bleeds bc I don't like how they sound, just my opinion.

[effectsbay]

You don't even need the resistor with the cap....it just makes the transition smoother. I leave them out of my guitar treble bleeds bc I don't like how they sound, just my opinion.

Hmm.. this is in a pedal, I wonder if that has something to do with it (not in guitar circuit)? If I take the resistor out.. it sounds horrible. Tin can - thin brittle and nasty. I put the resistor in, and it sounds like it should?

Thanks!
hank

[effectsbay]

I would try a smaller cap. Generally the sets the frequency and the resistor
limits the amount that the cap passes treble through, in relation to the pots volume
roll off.

Using a 1M resistor is going to be too big I think.
I would select a cap by itself and then a resistor to limit
the amount of treble you get when rolled off.

You don't NEED the resistor so you may want to try a cap
by itself an see what you get. Try 150p and up to start.

Sounds good. I don't have any caps smaller that .001uF, I'm assuming that I should be able to pick up some 150pF at radio shack then to test?

Thanks!
hank

[John Lyons]

Anything close to 150 will be fine but that's just a place to start.
See if you can get a sampler pack for different PF values, say
100pf, 200pf, 330pf 470pf etc. The value does not have to be exact
just in the ballpark for testing.

John

[joegagan]

is this an output volume control? what is the rest of the circuit? hard to answer without that info.

[GibsonGM]

Yeah, if it's too tinny, I would increase the value of the bypass cap.  BUT, at some point, you  will lose volume control, since you're bypassing it!!!  You just have to play with values; and you might like the limiting resistor in there, it's just a preference.