504 Pots

[METAL Rulez 4ever]

Hi all, Happy New Year. Hope all is well.

I havent posted in a while, many builds and projects have been completed in the meantime.

Anyway, i am rebuilding and customizing a J Bass and found these pots in it. Never seen or heard of A and B 504 pots ! Does anybody have info on them please and if they are worth keeping or replacing with A500K or A1000K pots please ?

Regards,
Naim.

24204

[fender3x]

Hi all, Happy New Year. Hope all is well.

I havent posted in a while, many builds and projects have been completed in the meantime.

Anyway, i am rebuilding and customizing a J Bass and found these pots in it. Never seen or heard of A and B 504 pots ! Does anybody have info on them please and if they are worth keeping or replacing with A500K or A1000K pots please ?

Regards,
Naim.

24204

504 means the same as 500K. A is an audio taper. B is a linear taper. So these would be a pretty standard setup with humbuckers.

If they are not noisy, then you could keep them. Some people like a linear pot for tone. I tend to prefer audio pots for both tone and volume so I'd be tempted to swap that one, but that's just me.

I think a Jazz with single coils would more typically have 250K pots. 500K will make them brighter. 1Meg pots might be a tad shrill.



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[METAL Rulez 4ever]

504 means the same as 500K. A is an audio taper. B is a linear taper. So these would be a pretty standard setup with humbuckers.

If they are not noisy, then you could keep them. Some people like a linear pot for tone. I tend to prefer audio pots for both tone and volume so I'd be tempted to swap that one, but that's just me.

I think a Jazz with single coils would more typically have 250K pots. 500K will make them brighter. 1Meg pots might be a tad shrill.



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Thank you Fender3X for you info, much appreciated. I found these pots very low in output. The pups are 6.4 and 7.1. I will change the pots and pick ups. I find 250K pots very dull and muddy and gets lost in the mix. I like a bright bass tone and then crank the bass on the amp head. That way i get low end and clarity.

[fender3x]

Then 500k is probably right for you. It's not uncommon with single coils, just not as commons as the 250K's.

The pots would mostly affect the highs, not the overall output. So if the output is low replacing them should help. The values you listed for them is in the ballpark, but resistance is only part of the story. Before getting rid of the pickups you might try getting them closer to the strings which should also boost output...if it's not enough you can swap them out...but raising them is cheaper ;-)

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[Simon Barden]

The pots won't affect the pickup volume, especially at 500k. If the output is low, there's either a high resistance solder joint somewhere, or some bad wiring. The pickup DCRs seem on the low side compared to the values of Seymour Duncan vintage style JB pickups, but without knowing the wire gauge used, you can't jump to conclusions about lower outputs just from the DCR, (though it does seem like it).

[fender3x]

The DCR is right about where a lot of single coils are, but that's not saying much. It's right about where a Dano would be..

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[METAL Rulez 4ever]

Thank you Fender3X and Simon, much appreciated for both your info.

I did try raising the pickups, that is always my first go to solution, however, i got the pickups as high to the strings without the strings hitting the magnets and the out put is still low. I am replacing the whole electrics with new wiring and pickups. I am installing a Seymour Duncan Quarter Pounder (13.68) in the bridge and a BC Rich (6.74) in the neck. A500K pots for both the volume controls and A1000K for the tone control. I have 3 different capacitors to choose from EPM10, EPM33 and EPM47. I don't know if there should be a zero or zeros in front of those numbers. The 10 cap has 2A104J on it and another cap i found has 683J2AOSG. Which capacitor is this one and which cap should i use please ?

[fender3x]

The 10 cap has 2A104J on it

This one would work. It's .1u (microfarads). More typical would be .05u or .047u.

Here's an article that might help:

https://www.seymourduncan.com/blog/the-tone-garage/bass-tone-caps-from-the-top?close-mud-slide-warning=yes



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[METAL Rulez 4ever]

This one would work. It's .1u (microfarads). More typical would be .05u or .047u.

Here's an article that might help:

https://www.seymourduncan.com/blog/the-tone-garage/bass-tone-caps-from-the-top?close-mud-slide-warning=yes



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Thank you Fender3X. Here are two pages i am getting information from...

http://kaizerpowerelectronics.dk/theory/capacitor-code-table/

and

https://www.talkbass.com/threads/which-two-tone-capacitors.1128342/

The .1 cap is apparently a 200Hz cutoff. Is that too quick of a frequency to start cutting, might be a muddy sound ? I found more caps ranging from .1 to.001 uF (cut off from 200Hz to 2100Hz). I was thinking of using .001 (2100Hz) cap with two A500K volume pots and A1000K tone pot with the Seymour Duncan Quarter Pounder (13.68) in the bridge and a BC Rich (6.74) in the neck.. Whats your thoughts please ?

[Simon Barden]

You'll only get a full 200Hz cut-off with the tone control wound fully down. Also, the cut-off value will very from that figure a bit in your bass as it also depends on the pickup resistance and inductance. But yes, bigger capacitances give lower cut-offs. With a 1 meg tone pot, the 0.1uF cap certainly won't noticeably affect the sound with the tone control right up (others have done the maths and it's less than a 0.1dB change in the upper frequencies - you simply won't tell. So it all comes down to how dull you want the bass to sound with the tone control turned down fully.

How often and by how much do you actually use the tone control on the bass, as I know you generally prefer a brighter sound?

[fender3x]

This is where I personally would do some testing. My gut says that without the cap this bass will be very bright. Jazz, bridge pup much stronger than neck, 500K or higher pots. So with no cap this bass should be pretty bright.

The cap won't block all the highs, especially in a passive bass. So it's really about having a meaningful rolloff of some of the highs. If the cutoff is very high you won't hear it at all rolled off, or not much. Too low and it goes from bright to mud too fast.

The only way to know what you will like is to experiment. Wire up the bass and alligator clip some different caps in place to see what you think of the rolloff. Caps are cheap and the green and red gumdrops work just as well as the orange drops. For $10 you can get a small handful to try ;-)

I got similar advice on my ESB-4 project from Wierd Bits and the results surprised me, so I was glad I tested.






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[METAL Rulez 4ever]

Thank you Simon and Fender3X, I always have the tone fully open on 10. I have purchased alligator clips months ago and have different pots and caps through a bit of cardboard to test different set ups.

[Simon Barden]

Then the cap value won't really matter. If you want an even brighter tone, then either don't connect the tone pot up (but still fit it to save having an empty control hole), or buy a 'no-load' tone pot which has a break in the track in the fully open position. This takes the tone pot out of circuit when set on 10, then brings it in when it's turned down a bit.

https://www.realparts.com.au/catalogsearch/result/?q=no-load+tone&order=relevance&dir=desc

[METAL Rulez 4ever]

Then the cap value won't really matter. If you want an even brighter tone, then either don't connect the tone pot up (but still fit it to save having an empty control hole), or buy a 'no-load' tone pot which has a break in the track in the fully open position. This takes the tone pot out of circuit when set on 10, then brings it in when it's turned down a bit.

https://www.realparts.com.au/catalogsearch/result/?q=no-load+tone&order=relevance&dir=desc

Thank you Simon, much appreciated.

[JohnH]

Then the cap value won't really matter. If you want an even brighter tone, then either don't connect the tone pot up (but still fit it to save having an empty control hole), or buy a 'no-load' tone pot which has a break in the track in the fully open position. This takes the tone pot out of circuit when set on 10, then brings it in when it's turned down a bit.

https://www.realparts.com.au/catalogsearch/result/?q=no-load+tone&order=relevance&dir=desc

Oh, that's cool.