Maker Pro
Maker Pro

Pots!

reelingenious

Oct 26, 2017
1
Joined
Oct 26, 2017
Messages
1
I have recently rewired my guitar as per the Rickenbacker schematic. The Pickups are TV Jones, and after seeing this same schematic they recommended 500k log pots all round. Now I'm quite happy with the tone as I wanted "top end", hence the 500's I suppose. But the Mixer/blend pot is not very "gradual" and the softer neck PU gets blended in very late in the rotation of the pot, i.e., about the last 5%. Is this a pot value and or capacitor issue. I can follow a diagram, solder and understand some, but am basically an electronic novice!
 

Attachments

  • IMG_0510.jpg
    IMG_0510.jpg
    93.5 KB · Views: 99

kellys_eye

Jun 25, 2010
4,857
Joined
Jun 25, 2010
Messages
4,857
There are two types of potentiometer 'laws' - linear and logarithmic.

For audio purposes (volume) it is common to use the logarithmic law versions - if you fit a linear version you find the problem you're experiencing i.e. 'everything happens at one end'.

In tone control circuits the opposite happens - you need linear, not log.

Change the pot to the right 'law' and all will be well.
 

73's de Edd

Aug 21, 2015
3,365
Joined
Aug 21, 2015
Messages
3,365
Sir reelingenious . . . . .

Since you only have 2 connections, did you replicate the connections that were made into the old pot ?
Notice that the center connection is being the rotor . . . ..movable contact within the pot.
Either of the side connections are being the extreme connections of the resistor element.
Also do note that you are only making two wired connections into the pot.
There is being a 100% chance that you got the wire going to the center rotor CORRECT.

The other wire connection will go to one of the end connections of the pot.
If you choose the WRONG end to put it on the, the quick resistance change that you mention as
currently experiencing, may be at the full CCW position of the knob. (Whereas it should be at the
full CW position.

Try the connection alternatively at both ends and evaluate to see, which gives the desired
results.

One way will give you a s. .. l . . . o . . . .w and gradual mixing transition until you get
near the center of the pot, then a much faster change.
The other way would have that effect at the OPPOSITE position of the pots rotation.

I just don't know whether the pot is being at its min or max knob position . . .when expecting
max CW for maximum bass mix in.

Otherwise you go to the other option of using a linear pot which mixes in, all in accordance
to the percentage of its rotation that you have the pot set to.

BUT then, you wouldn't get that gradual / fine tunable adjustment, at one end of its range that a
conventional audio log pot would achieve, if being wired in to the correct end terminal.

Study below . . .
Take the full left line referencing and mulltiply by 5 to agree with your 500K pots resistance
Take the bottom line referencing and relate it to the position that your rotor is resting on the
pots peripheral resistance element.
Compare the resistance differences experienced when using the BLUE audio log pot and the BLACK
linear pot.
The micro adjustment permitted by the LOG unit becomes readily aparrent . . . . or its adverse
affect if it is wired in backwards.
( If a radio had its volume control (LOG) wired in backwards, it would turn on and be as loud as hell . . .
and then slowly decrease in volume . . . as you turned the knob further to the right )


POTTY TRAINING . . . . .REFERENCING . . . . .

image.php



Little Eddie Ricketybacker Gee-tar info . . . . . .

"
Volume potentiometers have also remained a standard 250K log type. Tone and mixer controls have, however, experienced a change in more recent years. These were originally 500K log type. They have now been changed to the same value as volume pots (250K log). Some of the re-issue guitars have the original value in these positions, others do not. "

73's de Edd
 
Last edited by a moderator:

Audioguru

Sep 24, 2016
3,642
Joined
Sep 24, 2016
Messages
3,642
I think the pots are shown connected backwards so I fixed the schematic.
The Mixer pot should be linear.
The capacitor values should be reduced to match the increased value of the pots for the same cutoff frequencies as the original.
 

Attachments

  • guitar pots.png
    guitar pots.png
    571.6 KB · Views: 97
Top