L 1000 Schematic Times 2

Seeing as how we are fortunate to count Paul Gagon as a member here, it seemed like a good time to give him a home to stretch out in and relax a little. Maybe exercise the grey matter and present a little history of the guitar and bass (amps too!) from his perspective as one of the eminent designers of our time.

Got questions? Great! Good questions might be, "What kind of windings are on the S500 pickup and why?" Or, "What was the thought process behind the MJ-4?" Troubleshooting questions should remain in the regular forums (he reads those too). Finally, please be mindful of how I feel about tech questions via PM or email.

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L 1000 Schematic Times 2

Postby PieterG » Mon May 14, 2018 5:19 pm

I am a hobby bass builder and player. I fell in love with the L 1000's tones when I played one a few years back for sale used. Always dreamed of building my own version with two pickups, separate volume controls, single treble tone control and bass "boost" control and of the course the on/on/on OMG switch like the original.
I purchased everything the circuit required originally plus an extra volume control. I am using Kent Armstrong "Claymores" for the pickups.
The diagram I downloaded from here.
I got ready to solder only to realize that it might not be as easy just added another volume control and doubling up some of the wiring connections.
Any idea of where I might be able to go to find out exactly what I need do or add?
I feel pretty confident reading diagrams and have soldered together a couple of ham radio kits and projects (N2PG). I am not confident on circuit design.
Any help would be greatly appreciated.
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Re: L 1000 Schematic Times 2

Postby Ken Baker » Mon May 14, 2018 8:02 pm

If anyone here has experience with the Kent Armstrong pickups you mention, maybe they can speak up. I have no idea at all. Nor do I have a V-V-T circuit anywhere. Sorry.

However...

Take a look here for something similar to what you're after.

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Re: L 1000 Schematic Times 2

Postby PieterG » Tue May 15, 2018 11:36 am

Thanks....will look at this later but, might do the trick.
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Re: L 1000 Schematic Times 2

Postby TDR1138 » Tue May 15, 2018 3:11 pm

I'll make the assumption that the Claymores are dual coil pickups with 4 leads.

I think the issue would be the selector switch for the modes. Question if you're going to do one switch to control both pickups or one switch per pickup. Either way, you'll either need a different switch (bigger, more terminals) or a second switch.

Stock L-1000 would take four wires from the pickup, feed them into a DPDT (double pole, double throw) switch that has 6 poles. At the switch, they would condense down to one ground and one hot lead out that would feed into the volume. You can't have the two pickups doubling up on the same DPDT switch. Notice on Ken's diagram that he linked how each switch consolidates the four wires out of the pickup into having a ground wire coming off and a white (hot) wire going to the pickup selector. You'd be doing the same thing but going to two different volumes.

If you're going to do one switch to control both pickups, you'd need a 4PDT on/on/on switch with 12 terminals. This would be used so that it would mirror having two independent DPDT switches right next to each other - i.e. 6 terminals would be used per pickup. If you're doing independent switches per pickup, then you just need two DPDT switches.

The other challenge is that the diagram Ken linked shows the flow of the circuit going Pickups --> switches --> selector --> bass cut --> treble cut --> volume --> out. So you would need to put the volumes where the selector is in that chain and not at the end where it is currently.

My suggestion: wire the pickups into the switches per the diagram. Wire up a VVT circuit based on a Jazz bass, with the hot leads from the switches connecting where the Jazz pickups normally would on that diagram. Tack the bass cut on at the end, between the hot out from the Jazz circuit and the output jack. See what happens. I'm not sure how it would work, as G&L likes to leave the volume last in the circuit, so I don't know what sort of impact this would have from a loading/capacitance issue. Someone smarter than me probably would. But that's where I'd start and experiment. You might find the bass cut to be unnecessary without the MFD pickups anyway.
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Re: L 1000 Schematic Times 2

Postby Ken Baker » Wed May 16, 2018 9:14 am

There's also this one. Single ON-ON-ON coil select switch controlling both pickups. The pickup select switch and volume control can be replaced with V-V controls and the active/passive switch can be easily removed. Then just add a 250KA / .047µf tone pot and you've got it.

Click the image for a PDF.

Image

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Re: L 1000 Schematic Times 2

Postby PieterG » Thu May 17, 2018 12:10 pm

Going to experiment with the first one suggested. Not having two separate volume controls is not a dealbreaker for me. I think it is safe to say I can use a rotary type switch in place of the toggle for pickup selection.
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Re: L 1000 Schematic Times 2

Postby Ken Baker » Thu May 17, 2018 1:00 pm

PieterG wrote:I think it is safe to say I can use a rotary type switch in place of the toggle for pickup selection.


Yes. You could even, and easily, replace the pickup select switch with a smart blend control.

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Re: L 1000 Schematic Times 2

Postby PieterG » Thu May 17, 2018 6:18 pm

Thanks so much Ken. Wish I could post a pic of how the bass I built came out. Loved that L 1000 I encountered. To my ears I swore there was a battery but, not. Just my perception! Felt I could take that one with me to any gig and it would fit in and also stand out as an individual statement...whether I knew what that really was
..LOL
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Re: L 1000 Schematic Times 2

Postby PieterG » Thu May 31, 2018 1:24 pm

Want to make sure I know where the coils start and finish. I know where for my Kent Armstrongs.
On the G&L White = North start. Black = North finish.
Green= South start. Yellow = South finish.
Hope I got that right.
Thanks in advance!
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Re: L 1000 Schematic Times 2

Postby Ken Baker » Thu May 31, 2018 2:37 pm

One coil will have white & black leads, with white typically going to the pickup select switch via the coil select switch. The other coil will have green and yellow leads, with green going to ground.

This will give you an idea how they're connected to a stock circuit. It's an old circuit (early to mid 80s) but clearly shows what is what.

https://www.bassesbyleo.com/paul/g&l_bb ... em_old.jpg

Not sure what you mean by start and finish.

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