G&L L-1000 Wiring

[Mcabe]

I was looking at how the G&L L-1000 is wired and seeing some contradictions in the documentation and how it appears some basses were wired at the factory. Does anyone know how the treble cut control should be wired?

In the attached schematic the signal goes into pin 3 of the treble pot, then the wiper connects to C4 to R1 to ground. But in the attached block diagram c4 connects pins 2 and 3. And from pictures that I have found on the internet it looks like R1 is omitted all together.

So what is correct? Schematic, block diagram, or picture of the control cavity?

 

[Mcabe]

According to this website, the 6.8K resistor is included in the schematic in error, and was never included from the factory. Interesting that the schematic and block diagram were never corrected.
G&L tech resources: Wiring harnesses

 

[fig]

I was looking at how the G&L L-1000 is wired and seeing some contradictions in the documentation and how it appears some basses were wired at the factory. Does anyone know how the treble cut control should be wired?

Good questions and good eye catching the differences.

We'll start with the 6.8kΩ fixed resistor first.

Alot of passive treble controls adjust from treble to bass to mud. BOO, mud! Adding a fixed resistor can electrically prevent the mud range from happening. You still have the full physical rotation of the pot, but electrically with a fixed resistor added, there's now enough resistance to prevent the mud range. Tone control is now treble to bass with no mud. G&L just picked a 6.8kΩ value. Here's a diagram I hope helps show how to tailor your own fixed resistance for mud limiting.:

Moving on, here's a chart I made a long time ago. 4 most common ways a passive Treble Control is wired shown in the top row and an improved connection of the same 4 in the bottom row (+). All of them work the same, installers choice which to use.:

In the attached schematic the signal goes into pin 3 of the treble pot, then the wiper connects to C4 to R1 to ground.

Your G&L schematic circuit is B+ in my chart above (minus the mud limiting resistor).:

For those passing thru, there's a jumper wire added between the wiper and treble end (terminals 2 and 3) of control pot in the + row of the chart. This mutes snaps, crackles, pops caused by debris, oxidation, smoke gunk, etc, in the pot. Without jumper, noise is loud. With jumper, you can still hear it but it's muffled a bit. Out of habit now, I just add the jumper. Absolutely no operational difference between the + and non+ versions.

But in the attached block diagram c4 connects pins 2 and 3.

I very rarely see this one, so I didn't include it in my '4 common connections' chart. Your G&L diagram is E (minus the mud limiting resistor) in the following chart:

Notice that in the 4 common connections chart, no matter which end the wiper is rotated to, the cap is still active. However, in E and F, the cap gets slowly shorted out when wiper is moving towards treble. With wiper at full treble, the cap is completely shorted, electrically not existing anymore. Only the pot resistance remains.

And from pictures that I have found on the internet it looks like R1 is omitted all together.

Not a biggy. Can be added in by the player whenever. Which, to me, is a better option. The same circuit can be used in multiple basses, yet sound different (different strings, resonances, woods, amps, etc). I encourage having the the player tailor their bass to their needs and preferences.

So what is correct? Schematic, block diagram, or picture of the control cavity?

They're all correct. (I bet you wish I'd said that at first, huh? LOL). G&L isn't obligated to keep us informed of their changes. They are all still fundamentally a passive Treble Control.

 

[Lo-E]

According to this website, the 6.8K resistor is included in the schematic in error, and was never included from the factory. Interesting that the schematic and block diagram were never corrected.
G&L tech resources: Wiring harnesses

I believe this to be true. I’ve never heard of an L1K in the wild that had this resistor. When I wired my L1K knockoff I didn’t include it.

As @fig points out, though, just because G&L never implemented it doesn’t make it a bad idea. It would be easy enough to remove if you decided you didn’t like it.

Also worth noting is that G&L stopped adding the .1uF loading cap to the “single coil with bass boost*” switch position sometime in the early 1990s, which changed that switch to a basic series/parallel switch. I went ahead and added a push/pull switch to mine so I could have either option.

*G&L’s “single coil with bass boost” is often referred to by users as “OMG mode.”

 

[skycruiser]

Good questions and good eye catching the differences.

We'll start with the 6.8kΩ fixed resistor first.

Alot of passive treble controls adjust from treble to bass to mud. BOO, mud! Adding a fixed resistor can electrically prevent the mud range from happening. You still have the full physical rotation of the pot, but electrically with a fixed resistor added, there's now enough resistance to prevent the mud range. Tone control is now treble to bass with no mud. G&L just picked a 6.8kΩ value. Here's a diagram I hope helps show how to tailor your own fixed resistance for mud limiting.:
View attachment 5036085

Moving on, here's a chart I made a long time ago. 4 most common ways a passive Treble Control is wired shown in the top row and an improved connection of the same 4 in the bottom row (+). All of them work the same, installers choice which to use.:
View attachment 5036108


View attachment 5036105
Your G&L schematic circuit is B+ in my chart above (minus the mud limiting resistor).:

For those passing thru, there's a jumper wire added between the wiper and treble end (terminals 2 and 3) of control pot in the + row of the chart. This mutes snaps, crackles, pops caused by debris, oxidation, smoke gunk, etc, in the pot. Without jumper, noise is loud. With jumper, you can still hear it but it's muffled a bit. Out of habit now, I just add the jumper. Absolutely no operational difference between the + and non+ versions.


View attachment 5036122

I very rarely see this one, so I didn't include it in my '4 common connections' chart. Your G&L diagram is E (minus the mud limiting resistor) in the following chart:
View attachment 5036133

Notice that in the 4 common connections chart, no matter which end the wiper is rotated to, the cap is still active. However, in E and F, the cap gets slowly shorted out when wiper is moving towards treble. With wiper at full treble, the cap is completely shorted, electrically not existing anymore. Only the pot resistance remains.


Not a biggy. Can be added in by the player whenever. Which, to me, is a better option. The same circuit can be used in multiple basses, yet sound different (different strings, resonances, woods, amps, etc). I encourage having the the player tailor their bass to their needs and preferences.


They're all correct. (I bet you wish I'd said that at first, huh? LOL). G&L isn't obligated to keep us informed of their changes. They are all still fundamentally a passive Treble Control.

What is the reason for shorting across the hanging part of the pot resistor? In the normal configuration there's no potential across it so it won't have any impact on the signal. (The chart with A/B/C/D).
Thanks!

 

[Mcabe]

They're all correct. (I bet you wish I'd said that at first, huh? LOL). G&L isn't obligated to keep us informed of their changes. They are all still fundamentally a passive Treble Control.

Thanks @fig! This is very helpful. It looks like the only difference between A/B , C/D, and E/F is the direction (and taper if non-linear) of the treble pot. To me, it seems natural that when the pot is turned 100% clockwise, tone should be wide open with no treble loss. I think that corresponds with diagrams A, C, E. How would you characterize the difference, if any, between A, C, and E? I would imagine that while not identical, they are electrically equivalent and would all sound about the same.

 

[Mcabe]

What is the reason for shorting across the hanging part of the pot resistor? In the normal configuration there's no potential across it so it won't have any impact on the signal. (The chart with A/B/C/D).
Thanks!

I think that helps with potential noise. If you have a scratchy pot, as you sweep the treble control, the wiper will make intermittent contact with the track which will show as infinite resistance to ground. This can create popping and crackle. By tying the hanging part of the potentiometer to the signal path (or ground) when the wiper is temporarily disconnected the signal still sees a 250K resistance to ground.

 

[skycruiser]

I think that helps with potential noise. If you have a scratchy pot, as you sweep the treble control, the wiper will make intermittent contact with the track which will show as infinite resistance to ground. This can create popping and crackle. By tying the hanging part of the potentiometer to the signal path (or ground) when the wiper is temporarily disconnected the signal still sees a 250K resistance to ground.

Thanks - this make sense. I didn't think about scratchy pots. Next time I come across a scratchy tone pot I'm going to try this connection to see if it helps!

 

[fig]

What is the reason for shorting across the hanging part of the pot resistor? In the normal configuration there's no potential across it so it won't have any impact on the signal. (The chart with A/B/C/D).
Thanks!

I'm just gonna use A and A+ as examples and we'll say a 250kΩ pot.

You're right, normal config (A) ignores the disconnected end as you said, and the jumpered config (A+) shorts out that end, electrically removing it. That end don't exist in either case. When there's no gunk in the pot and it's operating normally, there's no difference between the two configs.:

But, when there's gunk making the tone pot noisy (snap, crackle, poppy) the jumper makes a difference.

In the normal config (A), the gunk removes the wiper from the resistive track, meaning infinite resistance between the two. As you rotate the knob and the wiper chatters over the debris (contact, infinite, contact, infinite, etc), that large difference between the two makes for loud noise.

In the jumpered config (A+), the wiper is again removed from the resistive track by gunk, but the jumper still connects it to the resistive element (250k ohms or less, NOT infinity). As you rotate the knob and the wiper chatters over the debris (contact, 250k, contact, 250k, etc), that smaller difference between the two mutes the noise.

I hope that makes sense. Like Mcabe said, it lessens the noise of scratchy pots. You can still hear it, just not as loud. Sorry about my long-winded description LOL.

 

[Mcabe]

Sorry about my long-winded description LOL.

Much better explanation than mine!

 

[Mcabe]

On further reflection, I think what I meant by the "correct" way to wire an L-1000 circuit is how they originally came from the factory when they were first produced. From what I can gather, they omit the resistor but include the OMG cap. Based on the pictures I have seen I updated the block diagram and schematic to reflect how they were shipped from the factory.

Based on the the pictures linked above, the L-1000 used the metal control plate as a common ground connecting all the pots. (Fender often did this with his amps as well.) So the nuts attaching the pots to the control plate need to be clean and tight for everything to be properly grounded. The bridge and the output jack were not grounded by soldering to the back of the bass pot as shown in the original block diagram, but connected and screwed down to the copper shielding on the bottom of the control cavity (which connects the bridge to ground, and grounds the copper shielding).

 

[wellthenhey]

I believe this to be true. I’ve never heard of an L1K in the wild that had this resistor. When I wired my L1K knockoff I didn’t include it.

As @fig points out, though, just because G&L never implemented it doesn’t make it a bad idea. It would be easy enough to remove if you decided you didn’t like it.

Also worth noting is that G&L stopped adding the .1uF loading cap to the “single coil with bass boost*” switch position sometime in the early 1990s, which changed that switch to a basic series/parallel switch. I went ahead and added a push/pull switch to mine so I could have either option.

*G&L’s “single coil with bass boost” is often referred to by users as “OMG mode.”

Is there any way you could look at my attempts to wire up an L1K knockoff? I recently bought an L2K to convert into an L1K (cheapest option I had available). I used the Paul Gagon Wiring Diagram and every picture I could get my hands on to whip up my wiring diagram. Currently, my Knockoff L1K gives me parallel/single/parallel. SO CLOSE! I missed something somewhere, somehow.

 

[Lo-E]

Is there any way you could look at my attempts to wire up an L1K knockoff? I recently bought an L2K to convert into an L1K (cheapest option I had available). I used the Paul Gagon Wiring Diagram and every picture I could get my hands on to whip up my wiring diagram. Currently, my Knockoff L1K gives me parallel/single/parallel. SO CLOSE! I missed something somewhere, somehow.

I’ll compare your drawing to my notes when I have a moment.

 

[sunbeast]

One of the old G&L employees posted about the idea of the resistor on a tone control somewhere at one point, I wish I could remember well. Its was a nice technical run-through of what was happening and choosing values. The short of it is that it tames the resonant peak of the capacitor when the tone control is turned down. I have played with adding these to a few instruments though in practice I find I am usually able to just get the same effect by rolling a standard pot up a hair.

I've owned a few vintage L1000 and L2000 basses and can't recall ever seeing the resistor actually used in one FWIW. I feel like I did see it in some G&L instrument, which is what turned me onto the idea, but its possible it was just looking at the block diagrams years ago.

 

[wellthenhey]

One of the old G&L employees posted about the idea of the resistor on a tone control somewhere at one point, I wish I could remember well. Its was a nice technical run-through of what was happening and choosing values. The short of it is that it tames the resonant peak of the capacitor when the tone control is turned down. I have played with adding these to a few instruments though in practice I find I am usually able to just get the same effect by rolling a standard pot up a hair.

I've owned a few vintage L1000 and L2000 basses and can't recall ever seeing the resistor actually used in one FWIW. I feel like I did see it in some G&L instrument, which is what turned me onto the idea, but its possible it was just looking at the block diagrams years ago.

I installed it and was pleasantly surprised. Not world shaking awesome good, but it was cool.

At this point I am stuck at the switch - I cannot get to OMG mode.

 

[sunbeast]

I installed it and was pleasantly surprised. Not world shaking awesome good, but it was cool.

At this point I am stuck at the switch - I cannot get to OMG mode.

What is the issue you are having with OMG mode? It is just a series connection between the coils but with a 0.1uf capacitor tapped from the series bridge then run to ground

 

[wellthenhey]

What is the issue you are having with OMG mode? It is just a series connection between the coils but with a 0.1uf capacitor tapped from the series bridge then run to ground

I don't know. I've looked at all the pics and schematics til I see double. I even picked up from Low End Lobster's review video that the front coil is the one that is supposed to be muffled. I am about to undo and resolder the switch to see if maybe I missed a step.

 

[sunbeast]

I don't know. I've looked at all the pics and schematics til I see double. I even picked up from Low End Lobster's review video that the front coil is the one that is supposed to be muffled. I am about to undo and resolder the switch to see if maybe I missed a step.

My only thought is that the on-on-on switch connection orientation on yours in single-coil mode could be opposite from the orientation in the drawing (there are some switches that do connect the opposite way)- the switch should connect the 2nd and 4th lugs with each-other and the 3rd and 5th with each-other (counting from the top and across like reading a book). If this were reversed (1+3 connecting, 4+6 connecting) then the middle position would give you a strange parallel option but where one coil was being filtered through the cap instead of single-coil (so it would give you parallel/filtered-parallel/OMG). Also make sure you are using an on-on-on switch instead of an on-off-on switch, and make sure the ground point for the metal plate on the back of the pickup is grounded through the green coil connection and not a different one. I can't really see a way that you would get parallel in both outer positions of the switch though unless the switch is damaged somehow. I don't have an L1000 or L2000 anymore, but can open up my Fallout and take a picture if you don't get it figured out (Fallouts are wired like an L1000)

 

[-Boscoe-]

I don't know. I've looked at all the pics and schematics til I see double. I even picked up from Low End Lobster's review video that the front coil is the one that is supposed to be muffled. I am about to undo and resolder the switch to see if maybe I missed a step.

Are you still having trouble? If so please let me know. I’ve recently built a PCB based wiring harness for the L-1000 including a PCB topper for the on/on/on switch implementing parallel/single coil/OMG. I’ve spent a lot of time looking at this circuit recently and I feel I have a good feel for it now. Note that there were several variations of it through the years and I’m partial to the version that has the 6.8K ohm resistor on lug 1 of the treble pot (to provide a floor to the treble cut and prevent muddiness). Like many G&L things they were not always very consistent in how they implemented things.

As far as which coils are affected, here are the three positions on the pickup mode selector switch:
* Parallel - OMG capacitor bypassed
* Single Coil - bridge coil only - OMG capacitor bypassed
* OMG (Series) - both coils, OMG capacitor active across neck coil only

My website has information about the pickup as measured on my bench. I measured two recently manufactured pickups, so not sure if earlier models differed in wire colors (though they seem to be very consistent from what I’ve seen).

Menu - Pickup Wiring Reference

Pickup Wiring Reference

www.boscoemusic.com

I will very shortly be offering complete solderless wiring harnesses for L-1000s if people are having a hard time implementing the circuit.