Concentric pot(s) question:

[madjazzbass]

Are all concentric pots the same? I mean, I'm well aware that the top part controls one thing and the bottom part controls another ie Treble/Bass etc..; But here's my "dilemma", My jazz bass control plate has enough room for 4 potentiometers/pots and 1 mini toggle switch, the preamp that I want to install has a total of 5 potentiometers and at Mini toggle switch; Can I take 2 of those pots and combine them into one concentric pot so that I only need the 4 holes in the plate? or is there a "certain type" of concentric pot I need depending on what two things I wanna control/combine? Thanks ... I think/hope I made that clear

 

[Hundred proof]

Wasn’t a problem for my project, the stock EBMM Sterling has 4 knobs ... mine has 6 knobs the lower two are stacked (treble/bass). The reason on this bass, is that it has a split pickup each half sent to a separate preamp.

 

[madjazzbass]

Wasn’t a problem for my project, the stock EBMM Sterling has 4 knobs ... mine has 6 knobs the lower two are stacked (treble/bass). The reason on this bass, is that it has a split pickup each half sent to a separate preamp.

View attachment 3915981

Thanks, Awesome Bass

 

[Crater]

Most concentric pots will be two of the same value and taper, in other words, two 250 k Ohm or two 500 k Ohm pots. I don't think you can get mixed values without buying a pricey "modular" unit. Also, a concentric pot can't be a blend or have a push/pull switch or rotary switch.

 

[Matt Liebenau]

You’ll want to figure out what resistance and taper you need for each half and start looking. Something like bass/treble on an active eq will probably be the same on both but you can find ones that are different values. Also, if you want to mount through a pickguard or the body will make a difference.

 

[madjazzbass]

Most concentric pots will be two of the same value and taper, in other words, two 250 k Ohm or two 500 k Ohm pots. I don't think you can get mixed values without buying a pricey "modular" unit. Also, a concentric pot can't be a blend or have a push/pull switch or rotary switch.

These are different values, I don't think the price is bad. SHOULD they be the same value? Is it better if they are? Thanks.

 

[dwizum]

These are different values, I don't think the price is bad. SHOULD they be the same value? Is it better if they are?

There's really no "better" or "worse" without context - what values do you need for your project? You just need to find a pot that has the value(s) you need. Most concentric pots are the same value top and bottom but there are some that are different, like the one you posted. They're just not as common.

 

[Matt Liebenau]

It depends on what you are doing with it. That one would be ok for passive volume / tone. You’d probably need different values for stacked bass / treble in an active eq. We need to know what you’re doing before we can help you with specific products.

 

[dwizum]

Just to be clear, let's go back to your question in your first post:

is there a "certain type" of concentric pot I need

Pots for musical instruments are specified by a resistance value (in ohms) and a taper - which is the relationship between how much of that resistance you get as you turn the pot from end to end.

Concentric pots are just two pots stacked together. They're still specified the same, it's just that there's two pots in one package. So - if your active preamp uses 50k linear taper pots, it doesn't matter if you buy individual pots or concentric pots - you still need 50k linear pots. You could get two normal 50k linear pots, or a stacked pot that has 50k linear on top and 50k linear on bottom.

Or, for another example, if it uses a 50k linear pot for bass and a 25k linear pot for treble, and you want to stack bass and treble, you need a concentric pot with 50k linear and 25k linear stacked together.

And so on.

Arguably, taper isn't critical - if your instrument calls for linear and you use audio - or vice versa - you'll just find that the control feels skewed - you'll get a big change in value over a small portion of the pot's travel instead of even control across the whole range of travel. Some people just like certain tapers and use them regardless of what's called for in certain applications.

Resistance isn't super critical in some applications but can be in others. If you can't find the exact value called for, you can always just try whatever close value you can get your hands on, and see how you feel about it.

So - is there a certain type of pot you need? Yes - you need one that matches the taper and resistance that the preamp calls for, for the function(s) (bass, mid, treble, volume, etc) you want to control.

 

[madjazzbass]

There's really no "better" or "worse" without context - what values do you need for your project? You just need to find a pot that has the value(s) you need. Most concentric pots are the same value top and bottom but there are some that are different, like the one you posted. They're just not as common.

Thanks, I think I get it now, Much Appreciated.

 

[madjazzbass]

Just to be clear, let's go back to your question in your first post:



Pots for musical instruments are specified by a resistance value (in ohms) and a taper - which is the relationship between how much of that resistance you get as you turn the pot from end to end.

Concentric pots are just two pots stacked together. They're still specified the same, it's just that there's two pots in one package. So - if your active preamp uses 50k linear taper pots, it doesn't matter if you buy individual pots or concentric pots - you still need 50k linear pots. You could get two normal 50k linear pots, or a stacked pot that has 50k linear on top and 50k linear on bottom.

Or, for another example, if it uses a 50k linear pot for bass and a 25k linear pot for treble, and you want to stack bass and treble, you need a concentric pot with 50k linear and 25k linear stacked together.

And so on.

Arguably, taper isn't critical - if your instrument calls for linear and you use audio - or vice versa - you'll just find that the control feels skewed - you'll get a big change in value over a small portion of the pot's travel instead of even control across the whole range of travel. Some people just like certain tapers and use them regardless of what's called for in certain applications.

Resistance isn't super critical in some applications but can be in others. If you can't find the exact value called for, you can always just try whatever close value you can get your hands on, and see how you feel about it.

So - is there a certain type of pot you need? Yes - you need one that matches the taper and resistance that the preamp calls for, for the function(s) (bass, mid, treble, volume, etc) you want to control.

Thanks so much; I have a better understanding now, Thanks.

 

[madjazzbass]

So here's the preamp, I would like to combine the passive tone and the mids pot onto one concentric pot; So, As long as I get the correct values for each pot, and wire them (of course) the same as the originals, that should work just fine correct? Thanks.

 

[MPU]

Yes, as long as you have correct values and wiring. MEC has some (expensive) stack pots that have different values for each pot. Check the values you need from current pots and start searcing. Good luck, let us know how it goes.

 

[dwizum]

Yup it'll work fine if you get a stacked pot with the same values as the two you're replacing.

Note that this preamp already has a concentric pot for treble/bass. So you can't stack those, they're already stacked. It's unusual to find a concentric pot with one position as a blend pot (since blend pots have two separate circuits in them). So you can't stack that blend pot. And there's an active/passive push/pull on the volume pot, which is unusual to find for a concentric pot as well, so you probably can't stack the volume pot.

So in terms of using a concentric pot, you're kind of out of options of which pots to stack unless you can find a pot that allows the passive tone and mid to be stacked. That might be unusual though, as EQ pots for active preamps are usually lower values like 50k or 25k and passive tone pots are usually high values like 250k or 500k, and I can't recall seeing a concentric pot that mixed those different values (although I've never really looked).

Another option with that preamp would be to leave the mid select switch inside the cavity, i.e. not have it exposed - then it's more of a set once and forget it kind of control. I do that sometimes on preamps with mid select switches since I find that once I know which position I like, I just leave it there. Then you need one less hole.

Yet another option - use a stacked pot for the volume and passive tone controls (since they're likely to be easy to find values, like 250k or 500k), then replace the mids pot with a push/pull pot and have that be your passive/active control. This might be easier than finding a stacked pot in the right values for the mid and passive tone to be combined.

And even another option - replace the mid pot with a push/pull pot, and steal the caps off that mid select switch for your favorite two values. This will give you a two-position mid select with your mid pot, and you can then leave out the mid select switch - so you need one less hole.

You could always reach out to the seller and ask if they can offer anything or do modifications. I've worked with that guy on a couple weird things and he's been able to get his supplier to do special stuff outside of the standard products he has listed.

 

[madjazzbass]

Yes, as long as you have correct values and wiring. MEC has some (expensive) stack pots that have different values for each pot. Check the values you need from current pots and start searcing. Good luck, let us know how it goes.

Will do, Thanks a lot

 

[madjazzbass]

Yup it'll work fine if you get a stacked pot with the same values as the two you're replacing.

Note that this preamp already has a concentric pot for treble/bass. So you can't stack those, they're already stacked. It's unusual to find a concentric pot with one position as a blend pot (since blend pots have two separate circuits in them). So you can't stack that blend pot. And there's an active/passive push/pull on the volume pot, which is unusual to find for a concentric pot as well, so you probably can't stack the volume pot.

So in terms of using a concentric pot, you're kind of out of options of which pots to stack unless you can find a pot that allows the passive tone and mid to be stacked. That might be unusual though, as EQ pots for active preamps are usually lower values like 50k or 25k and passive tone pots are usually high values like 250k or 500k, and I can't recall seeing a concentric pot that mixed those different values (although I've never really looked).

Another option with that preamp would be to leave the mid select switch inside the cavity, i.e. not have it exposed - then it's more of a set once and forget it kind of control. I do that sometimes on preamps with mid select switches since I find that once I know which position I like, I just leave it there. Then you need one less hole.

Yet another option - use a stacked pot for the volume and passive tone controls (since they're likely to be easy to find values, like 250k or 500k), then replace the mids pot with a push/pull pot and have that be your passive/active control. This might be easier than finding a stacked pot in the right values for the mid and passive tone to be combined.

And even another option - replace the mid pot with a push/pull pot, and steal the caps off that mid select switch for your favorite two values. This will give you a two-position mid select with your mid pot, and you can then leave out the mid select switch - so you need one less hole.

You could always reach out to the seller and ask if they can offer anything or do modifications. I've worked with that guy on a couple weird things and he's been able to get his supplier to do special stuff outside of the standard products he has listed.

Yeah I was looking for a contact no.# or an email for them but couldn't seem to find one, Thanks for providing all the options, 'appreciate it.

 

[madjazzbass]

I came across this from another TB'r and thought it just may work for me as well if what I need is a 50k/250k stacked concentric pot. ... "For the pot you found, you would only need 1 resistor (not capacitor, they are different), of value 55.5k (to make the pot 50k) across lugs 1 and 3 of either the top or bottom pot".

 

[eottjake]

Most concentric pots will be two of the same value and taper, in other words, two 250 k Ohm or two 500 k Ohm pots. I don't think you can get mixed values without buying a pricey "modular" unit. Also, a concentric pot can't be a blend or have a push/pull switch or rotary switch.

My Prat has a concentric with Volume on top, passive tone below, and the volume is a push/pull for active. It can be done.

 

[madjazzbass]

... and then there's this idea: ... "All you need to do is bend back the 4 tabs on top of the donor pots and remove the wafers and swap them with the wafers in the stacked pot you started with!"

 

[dwizum]

My Prat has a concentric with Volume on top, passive tone below, and the volume is a push/pull for active. It can be done.

Can you find that pot anywhere as an individual part?

... and then there's this idea: ... "All you need to do is bend back the 4 tabs on top of the donor pots and remove the wafers and swap them with the wafers in the stacked pot you started with!"

I've done that a few times - sometimes it works fine, but IME it's one of those things that's harder than it sounds and often ends with a sloppy or scratchy pot.

Regarding contacting that seller - I just used the built in eBay messaging.