I’ve just been spending the last couple of weeks building up the tooling to cut these three Sirena Pistolera bass bodies. They’ve been chambered extensively to save weight and also affect the sound to some degree. I’m really excited about how nice they’ve been turning out to be.
Here’s a small run of walnut neck blanks for my Sirena Pistolera basses. I just started subletting a shop space from my friend Bruce Johnson. I’m sharing the space with a few other transient luthiers. Bruce wants to move his heavy woodworking operations to this shop, and I’ll be doing all my big wood here as well. Prior to this, I’d always done my work at my home shop, and I was limited by space and amount of mess I could make. I’m really excited about this development because it brings me a little closer to building my basses efficiently enough to bring my ideas to more people.
Let’s Start From the Beginning…
Over the last couple months, I’ve been immersed in developing my neodymium multi-coil sidewinder pickup. The idea was to make a bridge pickup that can do it all, but take up a smaller space than a traditional pickup. I figured that the entire width of the pickup would be used a the sensing area as there are no coils wrapped around the poles. It seemed to do the job pretty well. The relatively large neodymium magnets reproduce a lot of bass, while the naturally extended highs of the sidewinder design work together. I voiced a little onboard preamp to bring it up in a live band situation.
Building the Exotica Pickup
The Base Plate
The first two big problems to solve were the small amount space for the multi-coil assembly and keeping the magnets from crashing into each other. The neodymium magnets are really strong and somewhat difficult to manage. So, I designed a little base and had Bruce over at X-Strange machine a master that I could use for prototyping. The base has little trays built in that I could use to place the magnet assembly. I had to use a combination of press-fitting and glue. From there, I came up with a design for my bobbins. The trick was to be able to fit the terminals within the walls of the bobbin itself.
The bobbins are a combination of cast polyurethane and paper. I file grooves for the wires and attach them with CA glue. I figured that once they get encapsulated inside a block of epoxy, the paper and CA clue will be strong enough. They are pretty fragile, however t I only had one actually fail during the prototyping process – and that was purely due to operator negligence.
I wound these on The Funktronic Coil Genie.
I encapsulated the pickup in white polyurethane, but I wasn’t happy with the results. So, I bound and capped it with some nickel silver scraps I had laying around. Using various cements to affix the metal, I had better luck with the softer adhesives like E6000 or Gorilla Glue. For some reason, CA or epoxy wouldn’t hold the metal down. I’ve never had that problem – usually epoxy will do it.
After gluing, I soldered the cap to the binding with my soldering iron. In another life, I used to solder little structures like this all day long. Back then, I used a propane or oxy-acetylene torch. This was the first time I’ve done it with a soldering iron. It wasn’t too bad! The nickel-silver is really forgiving; I had a sand-through that I patched with a blob of solder (it’s really thin metal). Once you sand it, the patch is barely perceptible. At the very least, my cap and binding job will provide some shielding.
Putting it All Together
Despite the seemingly complex multi-coil assembly, the build process itself was pretty straightforward. It’s really a long series of many simple steps. Here’s a few images of the assembly process.
So far, my preliminary have been promising. It sounds really good! I’m really anxious to get it installed in a bass so I can test it out in the field.
Cool! Looks like the Modelo Uno has been featured in NoTreble.com! There’s nothing quite like seeing your work featured in a publication. Now that’s what I call excitement!
This week we’re checking out a funky and cool bass built by Jeremy Kirsch called the Sirena Modelo Uno. The four-stringer takes its design cues from similarly funky vintage basses.
OK I’m just going to post a weekly update – no pix today.
I’ve been working on the pickup and preamp. Using my new cardboard bobbins I wound a couple of coils with 44awg wire and increased the wind count. I after casting them I mocked up a pickup with the new ceramic 8 cores. From there, I rebuilt my preamp using a James tone stack instead of the Big Muff/Tilt tone stack.
1) On one of the cast bobbins, I somehow didn’t add enough hardener to the epoxy resin. I think that’s a pitfall that comes with mixing tiny 10ml quantities – if you’re off by just a tiny bit, that turns out to be a lot. Anyway, the piece didn’t cure and came out kind of rubbery. It’s good enough for testing, but not for a finished pickup. In the process of experimenting with various ways to build and cast my modular coils, I used all the pre-cut cardboard flatwork (I only ordered 14 pc to start). I ordered some more – it should be on its way soon.
2) I changed the preamp to a James/Baxandall tone stack because while the one-knob preamp was kinda cute, there just wasn’t any real control over the tone. Once you added any treble, you started to cut bass and vice-versa. With the James/Baxandall I’m able to fine tune the amount of highs and lows. I was even able to fine-tune the circuit itself by bumping 400Hz up by about 2dB. I also upped it to 18v much more headroom.
I know I’ve said this before, but this new pickup and preamp combo is a huge improvement. Keep in mind, pickup design is kind of a long process of experimentation that isn’t all that straightforward. In any case, the C8/44awg sidewinder rendered a much more controlled-sounding pickup. No more crazy high mids from the neos and with the ceramics wrapped in all that stainless steel, the biting highs are in the right place – nicely placed on top of a big cushion of clear lows and warm mids. With the neo versions, I felt like I was always struggling to contain this beastly pickup with these upper mids that just didn’t want to behave. Now I can really dig in to the strings without having to worry about it topping out.
I think it’s possible to design a really good-sounding neodymium pickup. I don’t know that the sidewinder design is the best application. I think maybe a more conventional humbucker with a steel core and the magnets placed on the bottom of the pickup might be a better approach with the neos. That keep the super strong neos away from the strings would make the magnets have to permeate all the way through the steel core. I dunno, just theorizing.
This week was mostly busy work. Most noteworthy, I took a few beginning steps to start a small production run of my Neodymium Sidewinder Bass Pickup. I dropped off some drawings of the parts with Bruce over at Johnson’s Extremely Strange Musical Instrument Company. Bruce is going to machine some nice masters that I can use to make molds for my parts. Basically, I decided that I have reached the point where I want to refine the design of my pickup and develop my production model. In the meantime, I’ll call around and get some quotes for getting the blades water-cut out of 430 stainless. I will start off with a few samples and see how they work with the molds. I’m feeling excited about it and I think it will be good to “finished” with my first design. As things progress, I’m sure I’ll be more excited about it.
On another note, I tried to take a few days off and give my brain a rest from pickup making. However, I failed spectacularly and came up with a drawing of a new sidewinder pickup that I think I can make reversible.