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  #21  
Old 09-09-2011, 07:04 AM
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Quote:
Originally Posted by 4848277 View Post
Here's what it should look like...



I think everything else will work the same if I do it this way.
You want to wire you volume pots the other way around, like on a Jazz bass or Rickenbacker. That way, when you turn one down it won't mute the other pickup.

If you wire it up this way (as Gibson does), you can't mix your pickups.

So, to be able to blend pickups, the pickup needs to be on the wiper of the volume pot, instead of the output.

I'd rewire that active passive switch for true bypass also.
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  #22  
Old 09-09-2011, 08:42 AM
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Originally Posted by SGD Lutherie View Post
But it's part of the preamp circuit. When the preamp is bypassed the signal going through the .1F cap isn't going anywhere. That has no effect on the bypassed signal. Same with the 2.2M resistor. It's such a large load that I seriously doubt you wold hear it.

But that is a sloppy way to do an active passive switch.
You know, I woke up this morning realizing that little detail... Oops.

At the node representing the output of the volume control (the wiper), the cap and resistor headed off to the preamp form a low-pass with such a high impedance that it's negligible.

I don't see how these can not be RC circuits, though. They have a resistance (the pot), they have capacitance - they will behave like RC circuits. The RLC of the pickup will have some effect, but it is unlikely to be dominant at the frequencies in question.

I'll be interested to see what results 4848277 finds.
  #23  
Old 09-09-2011, 09:50 AM
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Originally Posted by lowfreqgeek View Post
You know, I woke up this morning realizing that little detail... Oops.

At the node representing the output of the volume control (the wiper), the cap and resistor headed off to the preamp form a low-pass with such a high impedance that it's negligible.

I don't see how these can not be RC circuits, though. They have a resistance (the pot), they have capacitance - they will behave like RC circuits. The RLC of the pickup will have some effect, but it is unlikely to be dominant at the frequencies in question.

I'll be interested to see what results 4848277 finds.
They are sort of RC circuits, but were not intended as RC circuits. The R just happened to have been there, because you have a volume pot. My point is that the pot was not part of the filter equation. in an RC circuit, you choose the values of R and C to get the frequency you want. They didn't do that. The volume pot was already there, and they just tacked on the bass cut control, with no thought about the volume pot. They then picked a common value that worked.

It's the same with passive treble cut controls. You see the same values all the time regardless of the pickups because that's the values that have always been used. Not a whole lot of thought behind it really.

If you want to get more precise control you need to go active.

The preamp here is actually more of a treble booster. I think Leo went with this circuit over something like the Stingray because the tone controls work in passive mode.

So sticking some volume pots before this circuit might make it sound a little different, and that's just because you added a volume pot, but it's not going to break anything. it'a not a precise circuit to start with. Just a quick and dirty bass cut control. And how often do people use it anyway?
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  #24  
Old 09-09-2011, 11:31 AM
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Originally Posted by SGD Lutherie View Post
You want to wire you volume pots the other way around, like on a Jazz bass or Rickenbacker. That way, when you turn one down it won't mute the other pickup.

If you wire it up this way (as Gibson does), you can't mix your pickups.

So, to be able to blend pickups, the pickup needs to be on the wiper of the volume pot, instead of the output.
You're absolutely right about that David. Here's the correction... (NOTE: This is likely the final incarnation of the schematic for this mod.)



Quote:
Originally Posted by SGD Lutherie View Post
I'd rewire that active passive switch for true bypass also.
I may do that another day. I'm not too concerned about that at the moment.

Cheers!

Last edited by 4848277 : 10-25-2011 at 02:34 PM.
  #25  
Old 10-04-2011, 01:44 PM
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Thumbs up All done.

Just an update. I got all the parts to complete this "project" last week and put it together on Friday and it works quite nicely.

Here's how the bass looks now...


The upper is the neck pickup volume, and the lower is the bridge pickup volume.

The next mod I may do to it is make the onboard preamp true bypass, but I'm not in a hurry to do it. The factory wiring in the control cavity is quite the crow's nest, and I really don't feel like messing with it right now. I'm just gonna play it.

Cheers!

Last edited by 4848277 : 10-04-2011 at 07:05 PM.
  #26  
Old 10-08-2011, 02:33 AM
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Originally Posted by lowfreqgeek View Post
I don't see how these can not be RC circuits, though. They have a resistance (the pot), they have capacitance - they will behave like RC circuits. The RLC of the pickup will have some effect, but it is unlikely to be dominant at the frequencies in question.

I'll be interested to see what results 4848277 finds.
No, the RLC of the pickup is the MAJOR effect! Consider a tone control max rolled off. Where is the R? It's the SERIES R of the wire in the pickup! (Pot is zero!). But it's still not an ideal RC. The pickup has a relatively large L and that combined with C and R which is the loading of the volume pot/amp etc. Creates an RLC low-pass filtering action that basically creates the tone of the pickup(s). Adjusting these values to change tone is what a "varitone" is all about.

Point is that the common idea that the "tone" control is some kind of simple RC network is simply way too simple. The actual circuit is WAY more complex than that. And as others have noted, measuring the values in that circuit can be a bear as well (distributed capacitance for example). So my experience agrees with most others that trying to model pickups and bass circuits generally is doomed to failure. Which is why most of them are designed by people trying things and carefully listening to the results!
  #27  
Old 10-22-2011, 07:33 AM
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I really want to do the stacked volume thing with my l2000 Tribute and want the stacked volumes to take the place of the pickup selector switch. I want to use that hole for a different switch. I would connect the pickups to the coil tap switches I'm using, connect the output from the switches to the volume - and then what? How do I reroute the signal through the treble and bass controls? Do I need ne components or the stock stuff? I'm also yanking the preamp so this will be all passive. I'm also replacing the 250k treble pot with a 500k one. Thanks!
  #28  
Old 10-22-2011, 08:10 AM
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This is easy. Each pickup goes to the pickup selector switch after the series/parallel switch.

So remove those wires and wire each one to the volume pot. Then take the wire that came from the pickup selector and wire that to the output of the volume pots.

Wire the volume pots like on a Jazz bass.
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  #29  
Old 10-22-2011, 08:38 AM
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Quote:
Originally Posted by SGD Lutherie View Post
This is easy. Each pickup goes to the pickup selector switch after the series/parallel switch.

So remove those wires and wire each one to the volume pot. Then take the wire that came from the pickup selector and wire that to the output of the volume pots.

Wire the volume pots like on a Jazz bass.
Thanks for the quick response! I totally understand replacing the pickup selector switch with the volumes (in the volume spot, of course), but the only issue I'm having is that stock signal path goes PU selector switch>treble>bass>volume>jack. If I'm replacing the PU switch with volumes (which removes the volume pot between the bass pot and the jack in the signal path) do I take the wire that connects the outer lug of the bass to the outer lug of the volume and connect that right to the jack? what about the .0002 mfd cap between the outer and inner volume lug?

By the way, your PM inbox is too full to take any more messages.
  #30  
Old 10-22-2011, 10:00 AM
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I'm doin' it! I just bought a 250k concentric pot and knobs and will be replacing the single volume with this dual volume, freeing up a switch hole. I'm yanking the preamp, which frees up space and a switch hole. I'm going to use the three switch holes to wire up the pickups in series/parallel/inner coils/outer coils with a separate inner coil/parallel/outer coil switch for each pickup. I'm also replacing the 250k treble pot with a 500k treble pot. This thing is going to be crazy killer when I'm done!
  #31  
Old 10-22-2011, 11:27 AM
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Right, just run the output from the bass pot to the jack. That .0002 mfd was a treble bleed for the volume pot, so eliminate that.
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  #32  
Old 10-22-2011, 11:40 AM
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Originally Posted by SGD Lutherie View Post
Right, just run the output from the bass pot to the jack. That .0002 mfd was a treble bleed for the volume pot, so eliminate that.
EXCELLENT! This is going to work out better than I had expected! I was going to be yanking the pre and installing two switches for the series/parallel/inner/outer but now I'll have two volumes (much better than a pickup selector switch) and can use all of the switch holes for the coil taps. Now the only thing I won't have is separate series/parallel switches, but I'm okay with that. I really didn't want to have four switches - three is enough!

Thanks!
  #33  
Old 10-22-2011, 11:47 AM
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Originally Posted by fourstringbliss View Post
Now the only thing I won't have is separate series/parallel switches, but I'm okay with that. I really didn't want to have four switches - three is enough!
Why not? Replace the single series/parallel switch with one for each pickup. So now you will have two switches, one for each pickup.

If you use on-on-on switches, you will have series/parallel and single cil for each pickup. If you reverse the wiring on one of the switches, it will do either the outside or inside coils.

Line6Man had posted wiring for doing that, so maybe he will pop in.

[edit]

I just found a post of his with the image. You want to use the first box on the upper right, where it says "Series/North Coil?Parallel" and "Series/South Coil?Parallel." You just need to figure out which wire goes where.

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Last edited by SGD Lutherie : 10-22-2011 at 11:53 AM.
  #34  
Old 10-22-2011, 11:59 AM
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Originally Posted by SGD Lutherie View Post
Why not? Replace the single series/parallel switch with one for each pickup. So now you will have two switches, one for each pickup.

If you use on-on-on switches, you will have series/parallel and single cil for each pickup. If you reverse the wiring on one of the switches, it will do either the outside or inside coils.

Line6Man had posted wiring for doing that, so maybe he will pop in.

[edit]

I just found a post of his with the image. You want to use the first box on the upper right, where it says "Series/North Coil?Parallel" and "Series/South Coil?Parallel." You just need to figure out which wire goes where.

I guess I could, especially since I don't plan on selling this bass.

I'm using this set of wiring diagrams:




and both switches are splittable. This gives series/parallel wiring and you can choose inner coil/parallel/outer coil when the s/p switch is in parallel mode. This would be four switches (two on/on and two on/on/on) and I'd just have to drill another hole. It's also my understanding that if you replace the jumper wires on the series/parallel switch with certain strength resistors it eliminates the volume jump when going from parallel to series.

Last edited by fourstringbliss : 10-22-2011 at 12:02 PM.
  #35  
Old 10-22-2011, 12:10 PM
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Yes, you can divide the G&L switch up into two on-on-on switches.
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  #36  
Old 10-22-2011, 12:35 PM
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I've modified the switches this way before on an L2500 Tribute but it was just too switchy. I like the idea of blending a series bridge with a parallel or single-coil neck pup, I just have to decide if I really want another switch there.
  #37  
Old 10-22-2011, 12:49 PM
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Originally Posted by fourstringbliss View Post
I've modified the switches this way before on an L2500 Tribute but it was just too switchy. I like the idea of blending a series bridge with a parallel or single-coil neck pup, I just have to decide if I really want another switch there.
What are you talking about? You would have two switches, not three or four. One switch for the neck pickup, and one for the bridge. Done.

Each switch would select series/single/parallel for either pickup. So you can then switch the bridge to series and then the neck in single or what ever. Why would you need three switches? Te way the bass is now you can only switch both pickups at the same time, and not individually.

Here's my Ibanez bass when it was wired up like that:



See? Two switches, one for each pickup. Nice and simple.
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  #38  
Old 10-22-2011, 01:07 PM
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Originally Posted by SGD Lutherie View Post
What are you talking about? You would have two switches, not three or four. One switch for the neck pickup, and one for the bridge. Done.

Each switch would select series/single/parallel for either pickup. So you can then switch the bridge to series and then the neck in single or what ever. Why would you need three switches? Te way the bass is now you can only switch both pickups at the same time, and not individually.

Here's my Ibanez bass when it was wired up like that:



See? Two switches, one for each pickup. Nice and simple.
I see the misunderstanding. As is right now, with the concentric volumes freeing up a switch hole, I'm going to have three switches. One switch controls series/parallel for both pickups and the other two give inner coil/parallel/outer coil for each pickup. What I'm debating about now is splitting the series/parallel switch into two so each pickup can be in series/parallel/inner coil/outer coil separately.
  #39  
Old 10-22-2011, 01:26 PM
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Originally Posted by fourstringbliss View Post
I see the misunderstanding. As is right now, with the concentric volumes freeing up a switch hole, I'm going to have three switches. One switch controls series/parallel for both pickups and the other two give inner coil/parallel/outer coil for each pickup. What I'm debating about now is splitting the series/parallel switch into two so each pickup can be in series/parallel/inner coil/outer coil separately.
That switch layout is not going to get you what you want, i.e., series bridge/single neck. I would rather have the functionality than worry about filling holes. Maybe the third switch can switch between two different cap values for the treble cut tone control.

Either that or a "producer switch."
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  #40  
Old 10-22-2011, 01:37 PM
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Quote:
Originally Posted by SGD Lutherie

That switch layout is not going to get you what you want, i.e., series bridge/single neck. I would rather have the functionality than worry about filling holes. Maybe the third switch can switch between two different cap values for the treble cut tone control.

Either that or a "producer switch."
The diagram does work because I've done it before. I think I'll stick with three switches.
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