New to DIY pickups; trying to make a Quad pickup (4 individual coils in one unit)

[ferniff]

Trying to make a quad pickup for my bass. To be able to send each string to it's own amp (why not) but more importantly down the road, take the pitch of each string and translate it to MIDI and be able to play a poly synth. I went through a few designs using a 3D printer. My system is pretty primitive; I have the mold taped to a stepper motor while I hold the wire, feeding it. I do about 1000 rotations with breaks between, and am aiming for 10,000 turns. My biggest issue is soldering the leads and just overall handling the wire. For the leads, to solder; is it advisable to get some lenght of wire, and fold it on itself while twisting it. For example you take a foot, and fold it in half a few times and twist it so you have a thicker piece to work with. Picture provided as an example.

[bbsailor]

ferniff

I have a simple expeiment for you to try to obtain independent outputs from each string.

1. Obtain an audio transformer of 8 ohms to 10K ohms or 20K ohms or higher. Turns ratio can be calculated by dividing 8 ohms or the input value into 20000 getting 2500. Now take the square root of 2500 and get 50. What ever voltage is induced into the single string will be boosted by about the transformer turns ratio.

2. Alligator clip a heavy stranded wire, to minimize resistive input losses, to a string behind the nut and behind the bridge to the 8 ohm input to the transformer. Attach the 20K ohm side or high end side of your chosen transformer to your amp input. Now, move a hand held magnet near the wired up string and listen to the sound when you vibrate the string. Longer lengths of magnet under the string will generate a higher output.

Look up how a ribbon microphone works with the bass string functioning like the ribbon vibrating in a magnetic field connected to a transformer near the ribbon. With your bass you can creatively use the neck truss rod and a conductive metal nut to extend the upper ends of all the strings to the body end of the neck and make a common ground return with the independent hot end of each string being behind the metal bridge with each bass string resting on something non metal and the ball end of the string isolated from shorting out to the metal around it. This end string point is the hot end of each strings connection point to the transformer along with the common truss rod connection. You will need to mount 4 transformers in the 4 string bass to carry individual string outputs in a 4 conductor coax split into 4 single conductor cables with a connector to match your mixer input.

Even if you do not mount it to your bass, doing the alligator clip experiment will teach you something about an alternative to winding thousands of turns of very fine wire around a magnet.

Joseph J. Rogowski

[fizzyp]

Any progress on this project ferniff ? I came here because I need to make single string pickups for the same reasons as you.

[fizzyp]

My best idea so far is to manually assemble single string pickups this way:
1. take a single magnetic pole piece
2. epoxy a tiny disk on one end to make one end-stop for the coil
3. epoxy an anulus on the other end (disk with a hole) to make the other end-stop. The pole piece will stick out a tiny bit to give me as something to grab with an electric drill.
4. wind the pickup
5. glue a tiny two pin header on the bottom of it so I can poke it into a bread board
6. use small breadboard(s) as the basis for the pickup package, insert individual pickups and wire them in series/parallel/however just by plugging wires intot he bread board.
I like this strategy because each individual pickup is low investment. I can a make a bunch of them and try all sorts of experiments. If I want to tweak the sound of a specific string I can easily do that. If I want to change the series/parallel/humbucking/etc wiring I can easily do that too with no soldering.