TalkBass Forums Help me make my tone pot smoother

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#1
09-18-2013, 11:27 AM
 Registered User Join Date: Nov 2008 Location: Madrid, Spain
Help me make my tone pot smoother

Hi all.

I am considering to update the wiring of my bass, and I'm sure you can help me.

First, let's introduce the "victim" : It is a 2002 Squier Standard Precision Bass. It has P+J routing, and I have mounted a DiMarzio DP126 set on it. The wiring stays original: 3 500K pots (V-V-T) and the stock capacitor (I don't know its value).

The volume pots work well, but the tone is not progressive. Rolled off it cuts the highs, and you will not notice any change while you roll it on until 1/3 of the turn, when all the brightness comes in suddenly. How could I make it smoother?
- A logarithmic tone pot?
- A different capacitor? (I don't know which is the stock one)
- A different value pot (250k, others)?

Also, which change would I notice if I changed the volume pots for 250k ones?

#2
09-18-2013, 11:29 AM
 I play bass so others don't have to! Please see Profile for Endorsement disclosures Join Date: Nov 2006 Location: Nashville, TN USA
250k pots will yield a little bit less bright tone overall - not a huge difference though.

I would try a linear taper 250k pot for the tone control for a smoother taper. If you like the volume pots, don't change those.
#3
09-18-2013, 11:31 AM
 Registered User Join Date: Feb 2008 Location: Zagreb, Croatia
With basses, the volumes are usually linear and the tone is usually logarithmic.
Your stock tone pot is likely a 47 nF one and that's a fairly standard value, changing that would change the frequency where your highs are cut. Change this to a bigger cap if you want a thuddier sound, a smaller if you want a more open sound.
Your stock pot is a 500K which gives a modern bright tone. Changing this to a 1M pot would make your bass excessively bright. Changing to a 250K would make it sound slightly darker and more "vintage". This actually applies to all pots - if you wanted a vintage sound other older Fenders and Squiers have, all pots would be 250K.

Overall, if you want to change just the sweep of the pot while keeping the tone it gives you, get a logarithmic (audio) 500K pot and swap your existing one with it.
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#4
09-18-2013, 01:13 PM
 Registered User Join Date: May 2009
Your tone pot sounds like an audio taper (logarithmic) pot. Yes, that's how they function.

Everybody above is really overthinking the process.

Simply swap it out with the same pot in a linear taper pot and you will be set.
#5
09-18-2013, 01:23 PM
 Registered User Join Date: Nov 2008 Location: Madrid, Spain

I am happy with the frequency cut (Rolled on = clanky: rolled off = warm), so I will go for the logarithmic pot. I think I will use a 500k one, because I want to keep some brightness. I am going to put flatwounds for the first time in this bass (and in my entire life), and I suppose that is going to suck some of the brightness I am used to.

Just to kill all my doubts. Should I keep the original condenser, or should I spend a few Euro in a new one? It is a pretty cheap piece, but I don't see why some condensers are better than other ones (apart from the precision in the capacitance), even though some of them seem pretty expensive. Am I losing something?
#6
09-18-2013, 01:42 PM
 Registered User Join Date: Nov 2008 Location: Madrid, Spain
Hi, iiipopes.

You may be right. I cannot find the wiring diagrams of my exact model, but looking to the Squier P Bass Special it seems than volume pots and the tone pot are different. Volume pots are marked as B500K, while the tone one is a D500K. Does that "D" mean logarithmic?

I have checked my bass and the 3 pots look the same, but the bottom is covered with soldering, so I cannot see any letter.
#7
09-18-2013, 01:48 PM
 Registered User Join Date: Oct 2007 Location: ann arbor, mi
I'm guessing you mean capacitor by condenser. Higher capacitance gives more tone cut (ie more bassy) when tone is at 0. When tone is at 10, there should be almost no difference.

Different capacitor brands have different sound qualities. At least that's what I hear - it's probably a small difference, but I've never personally tested them.

I would suggest getting a LINEAR and NOT LOGARITHMIC pot for the tone pot.

[Science-y bit]

Linear gives a smooth change. Turning the pot 1 higher will add 1 to the value of the pot's resistance.

Logarithmic, on the other hand, gives a curved change. Turning the pot 1 higher will MULTIPLY the value of the pot's resistance by 10 (for example - I don't know the real numbers). This is handy for volume knobs, as we hear volume in this same way. This is why you need to double your amp's wattage to get 1 more dB of volume.
This is not handy for tone knobs, as you'll get an uneven change, like you're experiencing.

[\end science-y bit]

Get a LINEAR pot for your tone knob. It will help.
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"master your instrument, master the music, and then forget all that &%$# and just play" charlie parker #8 09-18-2013, 01:50 PM  Registered User Join Date: Oct 2007 Location: ann arbor, mi It's hard to tell if a pot is linear or logarithmic without being able to see the markings (unless you're good with a multimeter). I suggest just buying a new pot, as they're pretty cheap, and it's always good to have an extra pot on hand anyways. __________________ "master your instrument, master the music, and then forget all that &%$# and just play" charlie parker
#9
09-18-2013, 02:58 PM
 Registered User Join Date: Feb 2008 Location: Zagreb, Croatia
A "condenser" is a common name in some languages for a capacitor.

Here's a graph of some of the common potentiometer tapers (sweep behaviors):

If the marking really is D500K, then you have an accentuated (slightly more extreme) log pot. Maybe a linear pot would work better for you.
__________________
Quote:
 Originally Posted by rtav Progressive Rock is like pornography - it can be hard to define but I know it when I hear it.
Quote:
 Originally Posted by Nev375 Fission is like fusion, but the original genre is obliterated in the jazz process.
Brony bassist #42
#10
09-18-2013, 03:07 PM
 Registered User Join Date: May 2009
Quote:
 Originally Posted by dcepeda I am happy with the frequency cut (Rolled on = clanky: rolled off = warm), so I will go for the logarithmic pot... Am I losing something?
Yes. Get a Linearpot, not logarithmic.
#11
09-18-2013, 03:57 PM
 Registered User Join Date: Nov 2008 Location: Madrid, Spain

Quote:
 Originally Posted by iiipopes Yes. Get a Linearpot, not logarithmic.
Hahaha, I got it. I was just typing my post when you posted yours.

Jefkritz, your explanation was very useful. My doubt came because of graphic equalizers: The band frequencies are incremented logarithmically. But then, as Stealth said, the frequency cut is affected by the capacitance, not by the impedance of the pot.

Stealth, your graph was also really interesting

So, to sum up:

Volume: Logarithmic pot.
Tone: Linear pot.

Impedances:
500k --> Standard sound
250k --> Vintage tone, less bright
1M --> Modern, brighter tone

Thank you all.
#12
09-20-2013, 01:49 AM
 Registered User Join Date: Aug 2009
Quote:
 Originally Posted by dcepeda So, to sum up: Volume: Logarithmic pot. Tone: Linear pot. Impedances: 500k --> Standard sound 250k --> Vintage tone, less bright 1M --> Modern, brighter tone Thank you all.
Standard wisdom. Probably wrong. Be prepared to try both tapers in both volume and tone. Generally in my experience a linear pot works best as volume and a log pot best of a tone.

Yes, I know all the "theory" , but for the volume it is a bass not a radio. What you want is volume reduction from full more spread out around max because that is the range you adjust volume in. You don't turn it down low like a radio. Hence a linear taper volume often works out much better.

Same goes for tone. A linear seems to be "theoretically" what you want, but a log pot often seems to spread out the tone changes better giving a less sudden shift. Of course tone controls are rather primitive and don't work very well even when working well. Hence:

Volume = linear
Tone = log.

So now who is right? No, don't trust me. The reason is that the taper of a pot depends upon the resistances hooked to it. A linear pot can act like a log pot if it's loaded just right. And that depends on how your bass is wired, the resistance of the pickups and such. Therefore there is ONLY one way to decide which pot to use. Get a linear and a log pot of the same value and try each. Whichever one works best for you is the "right" one to use. Period.
#13
09-20-2013, 02:38 AM
 Supportive Fender Join Date: Feb 2009
what bassbenj said.

you'll find linear pots mostly worthless for tone controls; you have to turn them almost all the way down to "0" before you get any change, at which point they act like switches.

i like 'em for bass volumes though, nice and smooth through the whole range.
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