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 Post subject: Need help picking a concentric pot
PostPosted: June 1st, 2016, 6:59 am 
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Location: West Orange, NJ
I just ordered a unique pickup from a company called Proto Guitars. It's a Jazz/Musicman hybrid. I specially ordered a lefty model, since flipping a righty and installing it would have resulted in the J coils being further away from the bridge. Here's the pickup (righty photo) and a YouTube demo:

Attachment:
Proto pickup.tiff
Proto pickup.tiff [ 601.04 KiB | Viewed 1107 times ]


https://www.youtube.com/watch?v=5kMYvCWg4rU

Pickup's due to arrive here Thursday. Anyway, my plan was to install a stacked concentric pot with each pot controlling to volume of each separate coil setup (Jazz and Musicman) so I could blend in any combo of either. Problem is most stacked concentric pots I'm finding are the typical Jazz vol/tone setup, so the pot readings differ (250k/500k). I've found 500k/500k audio pots, but my fear is that will change/darken the sound of the pickups, so I'm thinking 250k/250k is the way to go. But where to find them? Which brings me to question 2: will I also need to find lefty pots too, given the taper issues with righty pots? And then the final piece of the puzzle is aesthetically, I would like to be able to install these stacked Jazz knobs to maintain the look of the bass already, but I'm guessing that limits my pot options further.

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stacked jazz knobs.jpg
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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 8:15 am 
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Honestly, you don't have any options with all of the requirements you list.

Trust me... I've looked. For HOURS and HOURS... days, weeks and years on end, hoping one might pop up.

I've even looked for people that custom make pots, because they used to be out there. They'd make whatever you wanted for $100-$150 or so. They don't even seem to exist anymore.

Anyway, here is standard audio taper (log) concentric pot that is 250/250: https://www.allparts.com/EP-4485-000-25 ... _1441.html

In order for this to work properly, you'll have to wire it righty. Not the end of the world if it satisfies your needs in most other ways.

I also doubt it'll fit that knob setup you have, unfortunately.

My last bit of good news ( :lol: ) is that this pot will only work through a pickguard or control plate... the threaded shaft is not long enough to go through wood holes. So, shaft length and diameter are an entirely other can of worms. Imagine how frustrating it is when you DO find the correct values, but they won't work with your bass. :evil:

Here's another option I THINK would work...

http://shop.warwick.de/?&lang=en&modul= ... 7425A44028

The Warwick site has a ton of options you can't find anywhere else, but it's a difficult site to understand, the specs aren't clear and they're very expensive.

Again, this would have to be wired righty, and might be long enough to go through wood, and might also work with those knobs you picked... but it'll be over $50 by the time you pay for shipping from Germany.

Hope that helps... good luck!

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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 10:09 am 
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Thinking more about this, another option for you would be to go with linear taper pots since they work equally well both ways (lefty/righty), and, in my opinion, work better than audio taper pots when it comes to blending pickup tones together, since they have no curve. You can get more precise adjustments with them since the taper is distributed equally across the entire rotation of the pot, rather than stacked in the last 25% like an audio taper control.

I've converted all of my dual volume basses (jazz basses) to linear taper pots for volume, while keeping audio taper for tone.

Here's a source: http://www.azguitarparts.com/index.php? ... cts_id=138

Again, not sure if they'll work with your knobs, but the shaft is long enough for pretty much any application.

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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 10:49 am 
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Many thanks for your input, Addison. The bass in question I was planning on installing this in is a Spear Flextool bass (here's a righty photo), which has a pick guard that extends to the knobs so finding a pot that is long enough to pass through wood might not be an issue:

Attachment:
Spear-Flextool-Bass-Body-600x315.jpg
Spear-Flextool-Bass-Body-600x315.jpg [ 52.4 KiB | Viewed 1086 times ]


The current onboard setup is 3 vol/1 master tone. The switch on the lower horn, BTW, is a mute switch, which I find pretty useless so I was planning on making that a series/parallel switch for the pickup. (or some other combo of the other on board J & P pickups). Just to clarify, a linear pot would be a single pot that, when turned in either direction would be either/or pickup with the center position being the equal blend of both? (i.e. blend pot?). or do I have that wrong? I thought about just installing a blend pot, but I've had some basses in the past with blend pots that had the exact taper problem I mentioned as a result: all or nothing pickup output when turning in either direction with no subtle blend of both when you reached the middle position.

The knobs I had wanted to use are made for the Fender Jazz Deluxe and are your standard 1/4" bottom pot shaft and the top accepts about a 3/16" shaft.

Also, this pickup and setup I'm planning will have to play nice with the other on board pickups (J in neck and P in middle) in case I want to combine with others.


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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 11:28 am 
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pjmuck wrote:
Just to clarify, a linear pot would be a single pot that, when turned in either direction would be either/or pickup with the center position being the equal blend of both? (i.e. blend pot?). or do I have that wrong?

No, a linear taper pot is 0-10 like a standard volume pot you're used to, however the taper is literally a straight line (linear = line) from 0-10.

An audio taper pot has a curve from 0-10, so you'll get a slow increase in volume through most of the rotation of the knob with a big increase in the last 25% of rotation or so. If you think about that in reverse, it's why audio taper pots act like on off switches when wired lefty... you get 75% of the volume in the first 25% of rotation and then the rest from there.

With a linear taper pot, you have 25% volume at 25% rotation... 50% at 50% rotation... so on.

Logically, a linear control makes more sense, however, the guys who engineered this stuff found that adding a taper to the volume increase seemed more natural to their ears, so that's why tapers were added to the wipers. And it's true... audio taper pots sound more natural than linear taper pots when used by themselves.

Now, here's where it gets interesting... when using two volumes together and blending multiple audio signals, having that taper can actually work against you and you get what's known as "Volume Volume Syndrome," where turning down one pickup just a hair almost makes it inaudible.

You ever notice on a bass that has V/V/T that rolling off 25% of the neck pickup almost sounds the same as no neck pickup at all? It's because of that taper... in 25% of the rotation you've lost most of the volume of that pickup and it gets buried by the other pickup.

Using linear taper pots with multiple volumes decreases this effect dramatically, and allows you to blend two pickups together much, much better and in more useful ways than you can with audio taper controls.

Hope that makes sense... oh, and cool bass by the way!

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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 11:30 am 
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Useful diagram to help explain what I'm talking about...

Attachment:
image_38552.gif
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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 1st, 2016, 11:53 am 
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One more thing I forgot to mention… That diagram explains very well why linear taper pots work equally well wired lefty or righty and why audio taper pots will not.

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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 2nd, 2016, 5:24 am 
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Awesome help, many thanks. :)

Which brings me to the obvious question: why don't manufacturers just use linear pots more often, especially when making lefties?


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 Post subject: Re: Need help picking a concentric pot
PostPosted: June 2nd, 2016, 9:31 am 
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Good question.... at least for multiple volume controls.

Single volumes like a p-bass work much better with an audio taper pot.

One thing I should also add is that linear taper pots make for horrible passive tone controls... I'm not knowledgeable enough to explain why, but there is a reason for it.

Many active EQ's do use linear pots when there is a cut and boost, which is why these usually work well left-handed. Boost only controls are usually audio taper pots, however, so they will not work wired backwards.

Blend controls obviously work forward and backward, but you should wire them right handed (standard wiring) and only switch the pickup leads if you need change how knob rotation chooses pickups. If you completely reverse the wiring, the center detent (both pickups selected) will result in incredibly low audio and turning to each pickup will get significantly louder.

I don't know why this happens either... just relaying what I've learned through experience. :ugeek:

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