Colorsound overdriver Bass pot freq not changing

[pete_g]

I'm working off the original sola sound 71 schematic.
I've gone through the circuit at least 4 times and the pot does sweep through frequencies but it doesn't add any bass from 12 to 5 o'clock.
When I take the .1uf cap off from between lugs 1 & 2 it doesn't work at all.
I've traced the circuit at least 4 timees from start to finish to make sure I haven't missed anything.
Why do some schematics on the net not have that cap and the original does?
Any suggestions as to what may be the problem? I know its not the pot.
I know it may seem like a simple question but the ground lugs go  3-2-1 from left to right when looking at a horizontal line on a schematic right?

[nocentelli]

Can you post a link to the actual schematic you're using? As I recall, the bass pot is sometimes shown with a cap between lugs one and THREE (i.e across the two outer lugs) which would make it a proper baxandall bass control. Without the cap, it still sort-of works but will adjust the level of the whole frequency spectrum: This can be perceived as a bass boost and cut. Whether the original pedals had this cap, I have never been able to find out.

[nocentelli]

I know it may seem like a simple question but the ground lugs go  3-2-1 from left to right when looking at a horizontal line on a schematic right?

It's a simple question, but the answer is not so simple. The only lug you can always identify is lug 2, which is always shown in the middle, usually with an arrow pointing to the centre of the resistive track between the outer lugs 3 and 1. Some schematics actually number the lugs, and you have to hope the author of the schematic has checked this is the correct orientation for the pot to work as intended with the rotation of the pot (e.g. a volume pot should always show lug 3 receiving the signal, lug 2 as the output and lug 1 grounded - if 1 and 3 were reversed, the volume pot would mute the signal when fully clockwise). The other notation used is to place an arrow to denote the direction the pot is turned to "increse" the effect: In the solasound schem, the arrow on the bass pot would point towards the pot lug connected to the resistor coming from Q2's output cap, and the arrow on the treble pot would point towards the 10n cap coming from Q2 output cap.

If there is nothing on the schematic, you need to think about how the pot operates, or look up a layout for the same circuit/type of circuit, or worst case just guess, wire it up and prepare to switch the wires to lug 1 and 3.

[Electric Warrior]

Why do some schematics on the net not have that cap and the original does?

Because someone overlooked that cap when tracing the circuit or copying the schematic. It's always been there.

[pete_g]

For some reason it changes the bass amount when the 4.7 k resistor that comes off the 6.4 cap negative is connected to LUG 3, the 39K resistor end goes to LUG 3 and the other 4.7 K is on LUG 1.
I've tried a new pot also, but it made no difference.

I'm using the SOLA SOUND schematic.




photo upload

[Electric Warrior]

My Power Boost's bass control usually has a very subtle effect, but it depends a lot on the amp settings and how hard the pedal is pushing it.

[pete_g]

Sorry, I meant it alters the bass sound when the 6.4 cap negative is connected to LUG 2, the 39K resistor end goes to LUG 3 and the other 4.7 K is on LUG 1.

[bool]

If you have everything wired correctly, you can change the way the bass control works by changing the .1uF (100nF) cap across the "bass" pot ... to f.e. 47nF or even smaller (33n, 22n ...) and see which one works best for you.

[pete_g]

problem is there is a huge  difference in the bass sweep when it change lugs around and no noticeable difference when it is as the schematic says. just trying to track down where I may have gotten that part of the circuit wrong for the bass pot to function the way it does.

[Electric Warrior]

problem is there is a huge  difference in the bass sweep when it change lugs around and no noticeable difference when it is as the schematic says. just trying to track down where I may have gotten that part of the circuit wrong for the bass pot to function the way it does.

By wiring it up wrong? 
It does make a difference when wired up as per the schematic, just not always a huge one, depending on your setup. Its effect is quite subtle when used with a bridge single coil and very noticeable with a neck humbucker.

[pete_g]

problem is though that I don't notice ANY difference, whether in neck or bridge pickup.
Nevermind, I'll probably have to go through it again and see if I missed something.
Was hoping someone might see something I may have missed as I'm still just an amateur builder.

[Electric Warrior]

We don't know much about your setup. The bass control might work out of your amp's range..

You might want to adapt the capacitor or resistor values if it's totally useless for you. This site has the formula for this very type of tone circuit: http://sound.westhost.com/dwopa2.htm