• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

60s Jazz bass pots?

F

Fogoverla

May 19, 2013
84
0
Chicago, IL
#1
I am heavily considering fixing up an old bass that has a busted truss rod and completely ruined pups and pots.

I was looking to get the custom shop 60s pups and was wondering if I should be looking for certain pots to get the right tone out of them. Any suggestions for a cap to use? Looking for that John Paul Jones sound on the early Zep recordings.
 
#8
Fogoverla said:
Is CTS a standard term?
Click to expand...

CTS is a company which has been produced pots for more than 60 years.
Fender used "CTS" and "Stackpole" pots in the old days. CTS has the code "137" and Stackpole "304" (on the pots) ...

As far as I know, the Fender pots from America (USA and Mexico) are mostly CTS nowadays. They are reliable and of good quality.

60s Jazz Bass pots ...
- could be "CTS" or "Stackpole".
- all three were Audio pots (= log).
- had .05µF caps in 99.9% but with different tolerances (not depending on year).

Line6man was right with the .047µF because they are more common today - and in most cases there is no difference between .05 and .047 ...
 
#9
damos said:
...and later in 1968 fender choose the Ajax Blue molded 0.22 (PIO).
Click to expand...
Meaning, CBS, to cut costs, went to the Ajax....

Traditional Jazz bass wiring is 250kohm CTS pots with a .047 tone capacitor.

I believe the poster above has it backwards. For volume, a linear taper pot will tend towards having to roll the knob more than just a number or two to change significant volume. It is the tone pot that can benefit from being linear taper instead of audio taper for that same reason: finer gradation of control.

Now, that all said, here is how the differences work:

Change out for 500kohm pots: slightly higher resonant peak tending towards the upper mids, i.e. more presence.

Change out for .022 tone capacitor: well, guitars have that. not as much tone variety. I like a .033 so that some more mids are retained when the tone knob is rolled down.

Add a .01 capacitor in line between the bridge pickup hot lead and its volume control: gets rid of the "drop out" that tends to occur on all Jazz basses when both volume controls are dimed out.

Change the tone capacitor to .1: rolled off dub tone, especially with flats.

One other variant I do is to keep the 500 kohm volume pot for the bridge pickup to give good presence, and then solder a 1 meg resistor over the two outside lugs of a 500 kohm neck pickup audio taper volume pot. This makes the pot effectively a 333 kohm pot with a hybrid curve, gives just a hair more presence without getting edgy, which sits better in the mix, and gives a hybrid "ramp" for better control of the volume level in the mid-travel of the control. This, with the .01 inline capacitor to the bridge pickup and a .033 tone pot practically assure no problems for any sound guy keeping the bass properly slotted in the mix.
 
#11
iiipopes said:
I believe the poster above has it backwards. For volume, a linear taper pot will tend towards having to roll the knob more than just a number or two to change significant volume. It is the tone pot that can benefit from being linear taper instead of audio taper for that same reason: finer gradation of control.
Click to expand...

Nope. You do indeed want linear tapered volumes and audio tapered tones. But this is a highly controversial subject, and traditionally the audio taper would be used for everything.
 
#13
#14
line6man said:
Like I said, it's a controversial subject. There are a million threads out there, and fans of both tapers.
Click to expand...

RIGHT!

Volume pots can be linear or log (audio).
It depends on taste and how the volume pot is wired.

I have heard the old 1950s/1960s audio pots had another curve than 2010 pots? Anyway both pots have their fans.

Tone pots should be audio pots - but in some (especially old European) basses even linear tone pots can be found. But the "standard" for tone pots is audio/log.
 
#17
Cadfael said:
I have heard the old 1950s/1960s audio pots had another curve than 2010 pots?
Click to expand...

I have no idea, but tapers are highly variable.
a_taper-asml.jpg

Note, also, that many log taper pots are actually made up of two linear sections joined in an approximation of a log taper, because it is easier to manufacture pots this way.
Link Removed
 
#18
iiipopes said:
Volume controls need audio taper pots. Here's why:
Click to expand...

Unless you want to MIX two pickups. Then you want linear taper. Otherwise most of you action occurs between 8-10 on the knob, and that's pretty tricky. If you have one pickup on 10, as soon as you get past 8 on the other it's pretty much out of the mix.

Audio taper pots are meant to give smooth volume changes when doing fades.
 
#19
line6man said:
Note, also, that many log taper pots are actually made up of two linear sections joined in an approximation of a log taper, because it is easier to manufacture pots this way.
Click to expand...
Yes, I am familiar with that, especially on lesser expensive pots, and that is definitely a statement we can both agree on. Smoothing out the transition between the two halves of the resistance wafer is why for bass and for neck position guitar pickups I usually use the 500 kohm audio taper pots and bridge the outside lugs with a 1 meg resistor to ground to bring the effective value down to emulate the resonant peak of a 333 kohms pot and smooth out the curve. Yes it does tend to flatten out the curve as well.

And if David says to use linear pots when blending pickups, then I defer to his expertise.
 

Latest posts

Top Bottom
Back