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Replacing pots in passive jazz bass
- Thread starter Wind Blade Khan
- Start date
If you are just wanting to make the bass be more versatile, I would highly recommend the following for a general purpose J bass user.
250K linear volumes (for more precise blending), 500K audio tone control (for that extra touch of high end shimmer that is easily rolled back). Whatever value of tone cap you like (I like .047uF), and install a push/pull for one of the volumes to make the pickups connect in series. Bass looks stock, but gets a lot of sounds.
Small tweaks based on usage...
If you tend to run fairly pure pickup combinations (all neck, both equal or all bridge) and need general volume adjustment, install a 250K or 500K M/N taper blend pot or 3-way switch and master 250K linear volume (with push/pull for series).
If you tend to play with a lot of grit or overdrive and roll the volume knob down to clean it up, use audio taper volume pots.
250K linear volumes (for more precise blending), 500K audio tone control (for that extra touch of high end shimmer that is easily rolled back). Whatever value of tone cap you like (I like .047uF), and install a push/pull for one of the volumes to make the pickups connect in series. Bass looks stock, but gets a lot of sounds.
Small tweaks based on usage...
If you tend to run fairly pure pickup combinations (all neck, both equal or all bridge) and need general volume adjustment, install a 250K or 500K M/N taper blend pot or 3-way switch and master 250K linear volume (with push/pull for series).
If you tend to play with a lot of grit or overdrive and roll the volume knob down to clean it up, use audio taper volume pots.
500 K pots will indeed give you more high mid peak (the frequency at which the inductance of the pickup(s) and cable capacity) resonate when the volume and tone controls are up all the way, but...they also give you less high frequencies (hi mids and above) when you turn the volume control down to less than full. 250K pots mean your volume control acts more like a volume control, 500 K pots means your volume control acts like a volume and tone control at the same time. If that's what you like, fine, but I prefer my volume control to just be a volume control.
If your pots aren't scratchy, I agree with some of the above folks that changing them is a waste. That money could do more good elsewhere - a new set of strings, for example.
Man, were you born with a bass book atlas !!
Lot of info that's over my head lol..lol..
Haha! Just the results of lots of tinkering around with my Js and J derivatives. I do my own wiring and such, so it's cheap and easy to experiment.
Yes, I installed that harness on a passive MIJ Jazz.
The link I provided is for his eBay store. I'm sure you can contact him there. I never had a phone number.
Incidentally, I kinda agree with those saying you'd probably be wasting your money replacing controls if you're not actually looking for a change in sound and there are no defects in the pots you have. I WAS looking for a change (hence the series/parallel option). I also installed DiMarzio Area J's, and a set of Hipshot tuners. This combined package is what made the big difference I referred to, not just the pots upgrade. All of these were a step up in quality and/or tone from the stock components on this particular Japanese J.
Pot value for the volume pots does not have a very big effect on the resonance peak. 500k pots mainly filter out less of the high frequencies and do no really change high mids. They work just as much as a volume control. Turning them back a bit gets you the sound of a 250k pot at a slightly lower volume that’s all. The taper of the pot is different though, you either like that or not.
I concur with this. On my Jazz Bass, I didn't like how the audio taper volume pots seemed to have an effect only at the very upper limit of their travel. I replaced them with linears and enjoy them much more now.
That depends on your definition of "very big". Below is the frequency response (electrical part) of a Jazz bass loaded with 250K versus 500K pots - in this example, we're modelling one pickup soloed, with the volume and tone controls dimed. The volume and tone pots were set the same - either 250 or 500 K. The 500K pots give you a 4+dB peak, the 250K pots give you less than a 1 dB peak. I think that's significant, and the change is almost all in the high mids.
The odd thing about this is that changing a volume versus a tone pot doesn't make a difference at max volume and tone - each is an electrical load to ground, and the tone control is wired through a big enough capacitor that it's effectively a short at the resonance frequency, so all that matters with tone full up is the value of the pots. I ran curves with one 500K volume and one 250K tone versus the other way around, and the two curves lie on top of each other.
On a Jazz bass, though, there are two volume controls and only one tone control, so the choice of volume control pot value has more effect on tone (at max on the tone pot) than the choice of tone control pot value. Below are curves run with mixed pot values - the upper one is run with two 500 K volume pots, and a 250 K tone pot. The lower one is with two 250K volume pots and a 500 K tone pot:
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No, the tuners weren't meant to be a tone changer, but merely an improvement over the stock Japanese tuners. The Hipshots are really super, and the 27:1 tuning ratio is killer.
Lowfreek, I'm going to get a set of them just because of your advice lol...lol.. but tell me a little about the 27:1 ratio ? Also , do know how I can find out the year/ model of my Fernandes jazz bass?
