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What pots are better for P-BASS, 250K or 500k
Poll ended at Mon Nov 02, 2009 9:32 am
250k 33%  33%  [ 1 ]
500k 67%  67%  [ 2 ]
Total votes : 3
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Post subject: What is better 250k or 500k pots for P-BASS ?
Posted: Mon Oct 26, 2009 9:32 am
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Hi,
I am restoring an old deluxe p-bass (a copy I believe) which someone sanded down and partially took a part. I'm not exactly sure of the year, the pots are connected with cloth wiring, but the wires leading to the pickup are normal vinyl coated (pickups themselves), so I imagine it might be late 60's. There is a grounding plate under the bridge pickup. I plan to replace the three pots (currently 500k) with two pots, one of which (tone pot) will be the double pot (push pull) to blend in the neck and bridge pickup. This will allow me to install on a pickguard with only two holes for the pots (the three hole pickguards are very hard to find, and the current pickguard is too badly damaged to keep).

Therefore, I was wondering whether I should get 250k or 500k pots. I was initially thinking of going with 500k just to keep it as close to the original. However, from what I have read the 250k pots provide a more mellow sound preferred by many people.

What are your thoughts on this ?


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Post subject: Re: What is better 250k or 500k pots for P-BASS ?
Posted: Mon Oct 26, 2009 6:01 pm
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Dan,

Traditionally, but not, "in stone", the DC resistance of the pickup(s) generally dicated whether a 250K or 500K pot is appropriate. With a P-Bass pickup, the DC resistance of that is within 500K territory whereas the Jazz pickup is within 250K range.

Essentially, a 250K pot will ramp up the midrange a bit whereas a 500K will spread it out a bit to where your highs and lows will have a greater prominence.

The more dramatic of the differences will always be realized with a pickup's volume pot moreso than its tone pot.

Yes, you can also mix and match.

Hope this helps.

Dan72 wrote:
Hi,
I am restoring an old deluxe p-bass (a copy I believe) which someone sanded down and partially took a part. I'm not exactly sure of the year, the pots are connected with cloth wiring, but the wires leading to the pickup are normal vinyl coated (pickups themselves), so I imagine it might be late 60's. There is a grounding plate under the bridge pickup. I plan to replace the three pots (currently 500k) with two pots, one of which (tone pot) will be the double pot (push pull) to blend in the neck and bridge pickup. This will allow me to install on a pickguard with only two holes for the pots (the three hole pickguards are very hard to find, and the current pickguard is too badly damaged to keep).

Therefore, I was wondering whether I should get 250k or 500k pots. I was initially thinking of going with 500k just to keep it as close to the original. However, from what I have read the 250k pots provide a more mellow sound preferred by many people.

What are your thoughts on this ?

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Post subject:
Posted: Tue Oct 27, 2009 9:32 am
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[/quote]the DC resistance of the pickup(s) generally dicated whether a 250K or 500K pot is appropriate. With a P-Bass pickup, the DC resistance of that is within 500K territory whereas the Jazz pickup is within 250K range.
Quote:

Are you saying that if I measure the impedance of the pickup it could help me confirm what resistance would be right for the potentiometer ? I'm not sure about basses, but I do know that guitar pickup impedances tend to be somewhere between 5k and 12k. Consequently, what impedance should I expect for a 500k pot versus a 250k pot ?

Thanks for your help Martian.


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Posted: Tue Oct 27, 2009 10:40 am
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Dan72 wrote:
Are you saying that if I measure the impedance of the pickup it could help me confirm what resistance would be right for the potentiometer ? I'm not sure about basses, but I do know that guitar pickup impedances tend to be somewhere between 5k and 12k. Consequently, what impedance should I expect for a 500k pot versus a 250k pot ?

Thanks for your help Martian.
[/quote]

Yes. My rule of thumb is: Anything below 6.9K ohms I use a 250K pot. Anything above gets the 500K - UNLESS I'm deliberately trying to change the sound of the pickups.

Your P-Bass pickup is probably around 12K ohms; your J-Bass pickup is probably around 6.44K ohms.

For example and as previously stated, your P-Bass pickup is well into 500K pot zone and the J-Bass pickup is within 250K pot territory. Now, say I wanted a little more 'grunt' out of the P-Bass and a bit more 'twang' out of the J-Bass pickup, these are both examples of where I'd use the opposite pot values. Honestly, I can't think of a situation where I would though.

As to the master tone pot, the vast majority of the time I go with whatever is appropriate for the pickup with the highest DC resistance in the instrument. In your case, that would be 500K. And because its a bass, use a .047 or .05 microfarad capacitor.

Glad to help!

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Posted: Tue Oct 27, 2009 6:58 pm
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I just measured the impedances of the pickups.
My J-bass pickup is about 9.5 ohms and each P-bass is 7 ohms for a total of 14 ohms (connected in series).

Now I understand why there were 500k pots.

But its strange the the values are way-off those you mentioned (typical ?). I wonder why.

Thanks again for you input,

Dan


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Posted: Tue Oct 27, 2009 7:22 pm
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Dan72 wrote:
I just measured the impedances of the pickups.
My J-bass pickup is about 9.5 ohms and each P-bass is 7 ohms for a total of 14 ohms (connected in series).

Now I understand why there were 500k pots.

But its strange the the values are way-off those you mentioned (typical ?). I wonder why.

Thanks again for you input,

Dan


Dan,

My resistance values were based on more vintage type pickups and their readings. Nowadays, OEM pickups are oftentimes more powerful than their vintage counterparts; I neglected to take this into consideration when answering your post.

Either way, you definitely know now that 500K (alpha taper) is the way to go!

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Posted: Wed Oct 28, 2009 1:56 am
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500k goes well with high DC resistance so like when you back off the tone or volume.. the higher the value.. the cleaner it gets.. but at times 500k are a bit harsh

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Posted: Wed Oct 28, 2009 9:30 pm
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500k pots sound brighter. 250k pots sound mellower. Fender has used both values in P/J setups. My old JP90 had 500k pots but other passive Fender P/J's have used 250's.

It depends on what tone you are after. 500k pots are generally the choice for humbuckers and 250's for single coils in 6 string guitars.

I put 250's in a passive P/J that came stock with 500k's and it made the J pickup sound more like a P than a J. I may go back and put 500k pots in it.

About your pickguard, you can get a replacement made from the original by sending it to some of the replacement pickguard experts. A second choice would be sending a tracing, but the real pickguard would be better to send than a tracing, even if cracked or broken. Jeannie, Terrapin, Catalina and PickGuardian all do custom work. There are links to them on the REPLACEMENT/UPGRADE BASS PARTS page of my website. Just click the link in my signature below and then click on the REPLACEMENT link.


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