simple wiring question (2 soapbars, vol+tone)

[DodoBird]

Hello! I keep coming back with more questions for the community!
I picked up a set of Fat Stacks for my fretless build. I want a simple volume + tone separately for each one of the pickups. basically a P-bass wiring X 2
No active/passive , no coil splitting, no series/ parallel switching. Thanks but I'm not interested in that.
I know how to do the wiring but got stuck with the output jack - how do I connect the 2 separate circuits to the jack? can I have 2 hot leads wired into the jack directly?
This is the first time I'm not using a selector switch which is why I wasn't sure.. That is my main concern.

Other than that - a quick ask for recommendation - for a passive bass would you recommend 500K or the 250 K pots are enough? audio or linear? and 0.22uF or 0.47 uF caps?
I know how to solder, I just don't trust myself to pick the right parts.
Thank you very much in advance!

 

[LoveThatBass]

I prefer 250k audio taper and .047uf caps
Just duplicate this one for each pickup then tie both volume pots wire that is labled switch to the output jack as you do not need a pickup selector switch unless you want one

 

[DodoBird]

View attachment 4951259 I prefer 250k audio taper and .047uf caps
Just duplicate this one for each pickup then tie both volume pots wire that is labled switch to the output jack as you do not need a pickup selector switch unless you want one

Hey Thank you! if you don't mind - a few follow up questions.
I wasn't familiar with the 2 options for wiring the caps. Does it make a big difference (50's vs. Modern)?
Audio taper for both volume pots and Tone pots?
lastly, when you say "then tie both volume pots wire that is labeled switch to the output jack" - This is my main question and still not clear to me - do you mean 2 hot wires can feed into the output jack? that's not going to cause any issues?
Thanks!

 

[LoveThatBass]

After reviewing do the following. Use the 50’s wiring BUT connect the respective pickup and tone pot to the Center wiper lug then connect outer lug from each volume pot to the output jack. This will keep the volume of one pickup from effecting the other. If you don’t then when you turn one volume to 0 it will kill all sound. The 50’s method works best to keep the tone more or less separate.

To answer your question, the modern method is on a single pickup and allows for constant loading of the pickup. Constant loading is preferred so the sound doesn’t darken as much as you turn volume down but when two pickups with separate volumes are introduced (such as yours or Jazz Basses) if you wire that way then when one pickup’s volume is at zero it will kill ALL Sound from both pickups so with two pickups wiring the 50’s method but with pickup connected to the center wiper lug and the outer lug of both volumes connected to the output jack is preferred. If you were using one tone control like on a Jazz Bass the tone pot could be connected to the outer lug of the volume pots that connects to the output jack but using two tone controls you want to connect to the center lug with the respective pickup to keep the individual tone control from effecting the other tone control as much. Hope this helps.

 

[LoveThatBass]

Use this diagram but you can leave the two caps between the volumes and the output jacks off. This is viewed looking at the back side of the pots.

 

[Matt Liebenau]

Hey Thank you! if you don't mind - a few follow up questions.
I wasn't familiar with the 2 options for wiring the caps. Does it make a big difference (50's vs. Modern)?
Audio taper for both volume pots and Tone pots?
lastly, when you say "then tie both volume pots wire that is labeled switch to the output jack" - This is my main question and still not clear to me - do you mean 2 hot wires can feed into the output jack? that's not going to cause any issues?
Thanks!

To specifically answer your question, yes you can land both hot wires to the tip terminal on the output jack. No worries. This is essentially what a pickup selector switch does when it’s in the “both on” position.

 

[DodoBird]

Thank you both very much!
just to push the conversation a bit further, and not because I dispute what you are saying, I'd like to throw this into the mix:


this is a short video I just found that shows more or less exactly the wiring I was hoping for (you can even jump to 3:12) , however, It's not exactly like was described here in the discussion. So again, here are my questions:

1. Is there only 1 "correct" answer in wiring? (obviously there are many wrong answers that lead to shorts and dead ends, but what about correct ones?)
2. In the video, he connects some sort of "jumper" from Vol 1 to Vol 2 and then only from Vol 2 to the jack. that seems weird to me, wouldn't Vol 2 be overriding Vol 1 as well? (meaning if Vol 2 is all the way down, Vol 1 will necessarily be off )?
3. starting at 4:20, he mentions (exactly like @LoveThatBass wrote) connecting the pickup to the center lug. (Perhaps that is why he connects the jumper from vol 1 to vol 2??) what's the advantage of connecting the 2 Vol pots to eachother?
4. His connection between vol and tone is also in the center lugs (unlike the diagrams above). I guess I need to learn more about the 3 lugs and their function. (that's an action item for me!)
5. thinking of a jazz bass wiring, at the end of the circuit, the signal runs from the tone pot into the output jack (not the from the Volume). Is there a reason why I shouldn't connect: pickups->vol->tone->jack in my setup? instead of running 2 hot leads from the Vol pots to the jack, Can I run them from the pickups, to their respective vol, then to their tone pots and from there to the output?

Again, I'm not disputing, just trying to understand the different wiring options and what do they mean for the circuits.
I know I have a lot of questions, Please don't feel pressure or obligation, this is NOT URGENT. I'm learning. Thanks in advance to anyone who's willing to help.

 

[Matt Liebenau]

Yes, there are sometimes several ways to get to the same result in electronics.

Running a jumper from one volume to the next then to the output jack is electronically the equivalent of running both wires to the tip connection on the output jack.

Connecting the pickups to the center lug of the volume like a Jazz bass lets you turn one volume all the way down and the other pickup stays on. Wiring to the outside lug like a Les Paul means when one volume is all the way down all the output is shut off. Someone else can probably give a better explanation of the theory.

There are several way to connect a tone pot. I believe @fig has covered some of the differences in one of his posts.

 

[fig]

I know I have a lot of questions... I'm learning.

Very cool you're asking questions. And you got alot LOL.

I'm gonna post a simple schematic that's shows what you're wanting ("I want a simple volume + tone separately for each one of the pickups."). This is a very common circuit for two pickups in parallel.

I'd like to use the schematic (below) because I can redraw things to answer some questions you had in post #7. Added a pot picture with numbered terminals for reference to the schematic.

(See NOTE below pic). Do you understand it enough for me to keep using it?:

NOTE: I don't know fully what you understand about this stuff and what you don't. If I ever sound like I'm talking down to you or insulting your intelligence, it's accidental. Please overlook it. Just trying to keep things moving and on-point. Thank you.

 

[Drzejzi]

I'm glad I found this thread, as I have a similar problem: I want to add a second passive humbucker to a fretless and I'm stuck on choosing right pots. Decision fatigue kicked in.

 

[LoveThatBass]

Use fig’s diagram. It is very clear. Concerning the volume pots connected together you need to know each one is controlling the volume of it’s pickup via the center wiper lug. You are connecting the volume pot’s “output” (non grounded outer terminal) together with the other volume pot’s “output” together and routing it to the output jack. It really does not matter whether the the wire that comes from the two pot’s outputs connects to the bridge volume or the neck volume. It is electrically identical. Just use fig’s diagram and you will be set! You are making it harder than it needs to be.

 

[DodoBird]

Very cool you're asking questions. And you got alot LOL.

I'm gonna post a simple schematic that's shows what you're wanting ("I want a simple volume + tone separately for each one of the pickups."). This is a very common circuit for two pickups in parallel.

I'd like to use the schematic (below) because I can redraw things to answer some questions you had in post #7. Added a pot picture with numbered terminals for reference to the schematic.

(See NOTE below pic). Do you understand it enough for me to keep using it?:
View attachment 4953534

NOTE: I don't know fully what you understand about this stuff and what you don't. If I ever sound like I'm talking down to you or insulting your intelligence, it's accidental. Please overlook it. Just trying to keep things moving and on-point. Thank you.

Yes! I understand the diagram and I believe the wiring is clear to me. Thank you!
one question though (of course...) - I see the tone cap connected to lug 2 of the pot on one side but then connected to the hot lead on the other side? shouldn't the cap be grounded on the other side? or am I reading this wrong?
Thanks!

 

[fig]

LMAO! I was just gonna post all the stuff below when you posted. Fortunately the answer to your tone cap connection question is in here. Here's what I was just about to post...

...how do I connect the 2 separate circuits to the jack? can I have 2 hot leads wired into the jack directly? ...That is my main concern.

Yep, you can connect two wires to the output jack. Matt Liebenau and LoveThatBass explained why perfectly. As is the nature of 2 parallel circuits, the individual pickup circuits have to come back together at some point (in this case, the Jack) to work properly.:

In the video, he connects some sort of "jumper" from Vol 1 to Vol 2 and then only from Vol 2 to the jack...
3. ...what's the advantage of connecting the 2 Vol pots to each other?

The same thing applies, in that both outputs from each volume pot have to electrically merge again, which they do at one terminal of a volume pot. The advantage of connecting it this way is using as little wire inside a cramped control cavity as possible. It's how I, and most folk, would wire this circuit.:

So, looking at all three schematics I posted, you should see all three are electrically the same, meaning they'll work the same. Up to you, the installer, how you wanna physically wire it.

4. His connection between vol and tone is also in the center lugs (unlike the diagrams above). I guess I need to learn more about the 3 lugs and their function. (that's an action item for me!)

The two are unlike each other because there are actually 4 common ways a passive tone control (tone cap and tone pot) can be wired and connected to the hot signal. All 4 ways work the same. You're seeing two of the four. Here's the four common ways. Each will give you bass when knob is full CCW, treble when knob is full CW (you can swap wires if in want CCW = treble, CW = bass):

2...wouldn't Vol 2 be overriding Vol 1 as well? (meaning if Vol 2 is all the way down, Vol 1 will necessarily be off )?
3. starting at 4:20, he mentions (exactly like @LoveThatBass wrote) connecting the pickup to the center lug...

After I do some adulting stuff and redraw a bit, I'll post a schematic showing how NOT to connect the two volume pots in a parallel circuit. Not connecting each pickup output to the center lug (terminal 2) of each volume pot will have either volume pot controlling the volume of the entire thing.

 

[DodoBird]

This is so clear! Thank you very much!

 

[Matt Liebenau]

Thanks @fig! I understand how the electronics works but you explain it quite well.

 

[fig]

2. ...wouldn't Vol 2 be overriding Vol 1 as well? (meaning if Vol 2 is all the way down, Vol 1 will necessarily be off )?
3. starting at 4:20, he mentions (exactly like @LoveThatBass wrote) connecting the pickup to the center lug...

Volume pots can accidentally be wired to allow each vol pot to override the other. Kinda don't want that LOL. For parallel circuits, pickup to middle lug (terminal 2) is the only way to keep independent volume operation.

So, here's an example of wrong...:

Notice the volume pots in this schematic. Each pickup now goes to each vol pot's top lug (terminal 3). Middle lugs (terminal 2) are now the outputs. WARNING! Don't do this at home LOL.:

With both volume pots on, it's sounding great!:

So you turn the neck volume OFF. Aaaand you just killed all of your volume! I hate it when that happens LOL. You just blew your chance for that bridge pickup enhanced Jaco Pastorius tribute solo coming up next measure LOL.

With neck volume pot OFF (terminal 2 now grounded), the neck pickup signal is blocked by the resistance at the top of the neck pot (terminal 3). The bridge pickup signal gets grounded thru the neck volume pot, bypassing the jack.

Each volume pot now controls all the output volume. The volume will always equal the lowest pot setting. In other words, each volume pot is a Master Volume.

So, yeah, don't try this at home.

 

[HeadWind]

My understanding is that wiring two VT circuits in parallel doesn't allow independent tone controls. Good thread: 1960s Jazz Bass - Isolated Dual Stacked Vol/Tones - How does it affect tone? See @RobbieK 's posts in that thread. He's the man.

 

[fig]

My understanding is that wiring two VT circuits in parallel doesn't allow independent tone controls. Good thread: 1960s Jazz Bass - Isolated Dual Stacked Vol/Tones - How does it affect tone? See @RobbieK 's posts in that thread. He's the man.

I agree, I've learned so much from RobbieK's posts since I joined.

Lack of independent tone controls only happens when both volume pots are full on in a parallel circuit.

If one, or the other, volume pot is dialed back from full on, some resistance is added and starts isolating the tone controls, giving separate tone control action again.

Here's how all that works.

When both volumes are maxxed at 10 (continuity between terminals 2 and 3), a direct connection is made between the tone controls. Both tone controls interact, each acting as a Master Tone Control. Screw that LOL:

Dial either volume (or both volumes) back and resistance is added between terminals 2 and 3. This added resistance starts isolating the two tone controls. The amount of isolation depends on amount of resistance. More resistance = more isolation.:

Many players seem to play with both volumes maxxed, which means no isolated tone controls. RobbieK addressed this by adding two permanent resistors on the output of each volume pot for permanent isolation when both volumes are maxxed (post 6 of your reference, 3rd schematic and associated text down). He suggests 15kΩ value resistors as starting point. That value depends on how much isolation you prefer, so you gotta use your ears.:

 

[HeadWind]

Yup, RobbieK is the man, but your figures are nicer! Especially with the audio taper on volume controls, it is hard to "mix" relative contributions from two pickups (I understand the science behind audio taper, but in practice it seems to make pots almost on/off switches). So I, like most people, run both at 100%. The one VTVT bass I have, I just resign myself to knowing that just one tone pot works. Not worth it to me to wire in resistors. If I were going to whip out the soldering iron, I would convert it to VVT or VBT (stacked knobs so only two holes to fill). But that's just me.

 

[fig]

The one VTVT bass I have, I just resign myself to knowing that just one tone pot works. Not worth it to me to wire in resistors.

I'm the same way LOL.

At least folk that want tone control separation with both volumes maxxed have an option.