Tribute L2K Single Coil Query...

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Tribute L2K Single Coil Query...

Postby b17krk » Wed Sep 05, 2018 8:36 am

After much time deliberating on whether to attempt to modify my Tribute series L2K for some single coil action, and then just as long deciding if I should go the inner or outer coil route, I finally bit the bullet and modified it utilising the inner coils.

What I can say is that although there's the inevitable bit of single coil hum, I'm really pleased with the end result. There is one thing however that concerns me...

Since performing the modification I have noticed that in series mode the inner coil of the neck pickup and the outer coil of the bridge pickup now buzz whenever I touch the pole pieces, and what's troubling me now is that I can't actually remember whether it did this prior to the modification or not. I'm suspecting that it possibly didn't therefore I'm not sure what I may have done to cause this.

I know it's a long shot as you guys don't have my bass in front of you, but just to eliminate the possibility that I may have wired it up incorrectly here is a copy of a wiring diagram I knocked up in AutoCAD showing the changes I made to the switch. Please note that although the diagram shows the entire circuit, the only changes that I made were to the series/parallel switch...

Image

If anybody would care to take a look and tell me if anything stands out that could be a possible cause then I would much appreciate it.

P.s. Apologies for the poor image quality of the screenshot that I took, I can provide a PDF if necessary.
Last edited by b17krk on Thu Sep 20, 2018 1:22 am, edited 1 time in total.
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Re: Tribute L2K Single Coil Query...

Postby Ken Baker » Wed Sep 05, 2018 11:22 am

Around each pickup is a box. You show that box connecting to ground. Questions:

1. What is that box?

2. Why is it grounded?

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Re: Tribute L2K Single Coil Query...

Postby b17krk » Wed Sep 05, 2018 11:50 am

Hi Ken, sorry about that - the boxes are my representation of the pickup cavities where underneath each pickup is a ground lug screwed to the body with a wire routed to the back of one of the pots.
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Re: Tribute L2K Single Coil Query...

Postby Ken Baker » Wed Sep 05, 2018 12:25 pm

Okay. Thanks.

I'll ask Paul to take a look.

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Re: Tribute L2K Single Coil Query...

Postby Paul Gagon » Wed Sep 05, 2018 7:42 pm

Ken Baker wrote:Okay. Thanks.

I'll ask Paul to take a look.

Ken...

OK......here’s what I think is going on. When the coil configuration switch is in the single coil mode here’s what you got.
On the Bridge pickup, coil 2 is configured correctly with the yellow wire going to the Pickup Selector and the green going to ground, however, coil 1 has its white wire also going to the Pickup Slector and it’s black wire is just floating open. This allows some of the string signal to bleed into the output and if you were to touch the poles pieces you could possibly hear some noise.

On the neck pickup, coil 1 is configured correctly with the white wire going to the Pickup Selector and the black wire going to ground, however, a similar, but less problematic, situation occurs in coil 2. It’s yellow wire is floating while it’s green wire is grounded. This isn’t an unusual situation as such but string vibrations will generate voltage in coil 2 which will inductively couple into coil 1. Meaning you’re not really hearing the signal from only coil 1.

Sorry if this is getting a bit wordy. I hope this is making sense. Going a bit further into the issue of noise when touching the pole pieces of L-2000 MFD pickups, here’s something to be aware of. The pole pieces of the L-2000 MFD pickup are not grounded. If you have your amp turned up and you are able to touch the pole pieces with your finger you can hear a bit of noise/hum. This noise is a worse if you manage to touch the pole without simultaneously touching the sting or any grounded part of the bass (not an easy thing to do). In my normal day to day playing this has never been a problem for me but as I said, it’s just something to be aware of.
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Re: Tribute L2K Single Coil Query...

Postby b17krk » Thu Sep 06, 2018 12:59 am

Well I just want to say a huge thank you to both of you guys for taking the time to look at this for me, I really appreciate it!

Paul Gagon wrote:OK......here’s what I think is going on. When the coil configuration switch is in the single coil mode here’s what you got.
On the Bridge pickup, coil 2 is configured correctly with the yellow wire going to the Pickup Selector and the green going to ground, however, coil 1 has its white wire also going to the Pickup Slector and it’s black wire is just floating open. This allows some of the string signal to bleed into the output and if you were to touch the poles pieces you could possibly hear some noise.

On the neck pickup, coil 1 is configured correctly with the white wire going to the Pickup Selector and the black wire going to ground, however, a similar, but less problematic, situation occurs in coil 2. It’s yellow wire is floating while it’s green wire is grounded. This isn’t an unusual situation as such but string vibrations will generate voltage in coil 2 which will inductively couple into coil 1. Meaning you’re not really hearing the signal from only coil 1.

Sorry if this is getting a bit wordy. I hope this is making sense. Going a bit further into the issue of noise when touching the pole pieces of L-2000 MFD pickups, here’s something to be aware of. The pole pieces of the L-2000 MFD pickup are not grounded. If you have your amp turned up and you are able to touch the pole pieces with your finger you can hear a bit of noise/hum. This noise is a worse if you manage to touch the pole without simultaneously touching the sting or any grounded part of the bass (not an easy thing to do). In my normal day to day playing this has never been a problem for me but as I said, it’s just something to be aware of.


Hi Paul. please don't worry about being too wordy, (you haven't been by the way) and in truth I could do with all the help/information that I can get!

When I wired the switch up I was taking inspiration from the Daveplaysbass mod #7, but I clearly must have miss-interpreted his diagram. I have to admit that like a lot of people I have no real knowledge when it comes to electronics and circuits in particular. With this in mind what would I need to do now in order to correct my mistakes?
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Re: Tribute L2K Single Coil Query...

Postby Paul Gagon » Thu Sep 06, 2018 5:00 am

b17krk wrote:Well I just want to say a huge thank you to both of you guys for taking the time to look at this for me, I really appreciate it!


Hi Paul. please don't worry about being too wordy, (you haven't been by the way) and in truth I could do with all the help/information that I can get!

When I wired the switch up I was taking inspiration from the Daveplaysbass mod #7, but I clearly must have miss-interpreted his diagram. I have to admit that like a lot of people I have no real knowledge when it comes to electronics and circuits in particular. With this in mind what would I need to do now in order to correct my mistakes?

Kirk, I think it’s great that you are experimenting with your bass. I love it when people stretch out and wonder “What if I tried this?” As near as I can tell, you have the wiring for series humbucking and parallel humbucking correct. It’s only in the single coil mode where you have a bit of a situation. Now, technically what you have is usable and you seem to like it so just enjoy your bass. Unfortunately, with the switch you have, it’s not possible to ground out both wires of the coil you don’t want to listen to. This allows a small amount of that signal to get into the output. Having floating wires is done quite often and the greater majority of your signal is coming from the coils you want.

I can’t imagine you did anything to the pickups that made them more sensitive to hum while touching the pole pieces. I think that maybe you’ve just made yourself more aware of it. Like I said, it’s never been an issue for me.
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Re: Tribute L2K Single Coil Query...

Postby b17krk » Thu Sep 06, 2018 10:51 am

Paul Gagon wrote:Now, technically what you have is usable and you seem to like it so just enjoy your bass.


Thanks Paul, I certainly intend to! But just out of curiosity what would your approach have been in order to get single coil for the inners?
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Re: Tribute L2K Single Coil Query...

Postby Paul Gagon » Thu Sep 06, 2018 3:34 pm

b17krk wrote:Thanks Paul, I certainly intend to! But just out of curiosity what would your approach have been in order to get single coil for the inners?

Hummmm......what would my approach have been. OK, this might get a tad weird. I’m not sure how you feel about adding another switch but check this out. I would have each pickup going to a coil configuration switch that would let you select series humbucking, front single coil, or rear single coil. This way you could have your pickup selector on both pickups and enjoy inside coils, outside coils, both front coils, both rear coils, or both series humbucking. You would have to forfeit parallel humbucking to do all this.

I did this exact coil configuration on a bass I modified just a week or so ago. If you go to the “Paul’s Technicalities” section of this forum and look under “Turning a Kiloton Bass into a Megaton” you’ll see the wiring diagram I drew out. You basically would be pulling out the single 4PDT (on/on/on) coil configuration switch and replacing it with two DPDT (on/on/on) switches. One for each pickup.

It might sound a bit hairy but I think it could be very cool. As I said before, with the switch you have in the bass now, what you did is the way to do it. I have used multilayered rotary switches in L-2000 basses to get some interesting coil options but that can be a real rat nest of wires so.....ahhh.....let’s stick with this.

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Re: Tribute L2K Single Coil Query...

Postby b17krk » Fri Sep 07, 2018 2:17 pm

Thanks again Paul this really is inspiring stuff, I only wish I had the confidence and the know-how to attempt projects such as these.

It's funny really (and quite sad in some respects), but it's only been over the last year or so that I've really started to develop a keen interest in guitar electronics, and I kinda wish that I had discovered this long ago when my brain was slightly less spongy and could retain this new info a little better than it does now! The wife blames that sort of thing on having kids but I'm not so sure I can get away with that excuse! :lol:
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