Wunkay Mod, SERIES HB - Single Coil - OMG

[derick]

Here is my question... Is there a simple way to make the Pickup switch on an L-1000 Series HB, SC and OMG? I have modded an early '82 with a push/pull volume knob to add series HB to the Parallel HB - SC- OMG factory switch, and I find that I much prefer the Series setting to the Parallel. On other L-1000 basses, I mostly just use the HB position if the bass is noisy, and then only until the song starts, but I would actually use a series Humbucking setting if I had it.

[Ken Baker]

The only circuits that I have easily available would provide series/single/parallel with OMG on series mode. It's a passive L-2000 circuit, but it would be easy to carve out one pickup and the pickup select switch.

You might also look through these circuits from Daveplaybass.

Ken...

[derick]

Hi Ken, thanks for the response.

While Daveplaysbass' circuits are fabulous, they are way into the weeds for what I am thinking of.

I was thinking that perhaps reversing the wires on the humbucking terminals of the 3way DPDT switch might make the circuit series? I don't want to mess with the OMG circuit, just the parallel humbucking circuit.

[Ken Baker]

Any way we can get a clean drawing of what you currently have?

Ken...

[derick]

Oh, sorry for the confusion. I am thinking of making this mod from the dead stock circuit.

[Ken Baker]

Sorry for the slow reply.

If your bass has a two-position coil select switch you get parallel and series w/OMG. If your bass has a three-position coil select switch you get parallel, single coil, and series/OMG. These are both stock configurations. I have not checked this to be sure but I don't think you'd be able to get series, single coil, and series/OMG using the three-position switch. It has to do with the way the switch works internally.

An alternative would be to remove the OMG cap from its current location in the circuit and insert it into the signal chain after the coil select switch. To give yourself ON/OFF capability this connection could be done via an additional switch, such as the push-pull you mention above. While this seems odd, and maybe it is, there are a couple benefits. One benefit is that OMG would work in all three modes; series, single coil, and parallel. The other benefit is that the little bit of single coil noise from OMG mode would be gone. The only time you'd get single coil noise is when you're in single coil mode, which is to be expected. This would also work if you have a two-position coil select switch.

Howzat?

Ken...

[derick]

Thanks for weighing in.

While I've heard of the two-position L-1000 switch, and there exists a wiring diagram for it, I've never seen or heard of one on an actual bass. If any two-position Wunkays were manufactured, I suspect that they were very few. The L-1000 was Leo's ultimate iteration of the precision bass, a two position switch omits the "precision bass" position of the selector.

I'm thinking that what you're describing, putting the OMG cap after the coils are selected, would result in a massive treble cut in all positions. What makes OMG "single coil with bass boost.," as Leo described it, is the fact that a single coil pickup has more treble output than a humbucker, all things being equal. OMG keeps the treble from the single coil and adds in the capped bass output from the other coil. So while yes, there is a massive treble cut on one coil, the sonic result of OMG is single coil highs along with series humbucker lows.

I have some family members who are elecrical engineers, perhaps I'll toss this at them over the holidays.

[derick]

Okay, here's what I've got, borrowing and reversing (to match the view when the control plate is laid back) Paul's excellent switch matrix for the L-1000 coil switch.

This is the stock wiring for every wunkay that I've ever owned, which is about 12.

I believe that the mod I'm thinking of would require unsoldering the white wire from lug 6. It seems like then bridging lug 6 to the "black" lead somewhere might do it?

stock1k.jpg (98.09 KiB) Viewed 4967 times

[Ken Baker]

Here's what you can do: Go here and download the three switch pinouts for the ON-ON-ON switches. Draw in the leads to your coils and show where the signal comes off the switch as well as ground. Remember that the coil leads are black/white and green/yellow, respectively, for the two individual coils. The shunts that are pre-drawn are the internal connections of the switch in its various switch positions.

What this will do is allow you to "connect" your coils any way you want on paper and trace the signal path from hot (output to the EQ section) and ground.

This is what I do when I need to "test" or proof a circuit. Simple, just takes a few minutes, and give a graphical representation of signal flow.

Ken...

[derick]

Please bear with me, I am trying to wrap my head around this.

Is this schematic correct?

detail L1K schematic

l1000_schem_b.jpg (43.13 KiB) Viewed 4721 times

I can see where the 5 pin is grounded to the volume pot, but pins 3 and 4 are bridged, not 3 and 6. What am I missing? Is there a difference in pin numbering conventions?

switch2.jpg (184.26 KiB) Viewed 4721 times

Another thing that I don't understand, in OMG mode I am able to disconnect the .1UF capacitor and get full series humbucking. But it looks to me from the schematic that doing that would break the path and completely remove the black/white pickup coil from the circuit.

That isn't what is happening, but I don't understand why.

EDIT--- Okay, so if the OMG cap is removed, then the 3 pin (black pickup wire) is still connected to the 2 pin (yellow pickup wire) and we must get series HB from that?