David Schwab

The metallized polyester film capacitors from Radio Shack work fine for tone controls. The whole thing about the tone of caps has more to do when using them as coupling caps where the signal is going through them. For simple things like tone controls, polyester caps work fine, which is what orange drops are.

Good stuff there Mike. I am genuinely interested in what you are doing here. I still don't see where FEMM is all that useful in pickup design though since it only simulates the magnetic field. That's a small part of the whole.

Ah! I see! I like phase switches on guitars.

If you mean the 2 and 4 positions... that's not out of phase. They are in phase, but the pickups are close together. Out of phase is real thin and "snarky" sounding. Fender Mustangs have phase switches.

Clint Searcy (searcy string works) makes pickups exactly like that. The original Bartolini pickups had one coil per string, and Wal basses have two separate coils per string, forming a humbucker for each string.

I did it back in the 70's on my Ric bass. It's not very useful unless you want a REALLY thin tone with no bottom at all. If you turn one pickup down a little it brings the bottom back a bit. Also running them series out of phase has a bit more lower mids, but that's really thin sounding too.

You need to run a separate line for each pickup to use it for MIDI. You can't run them to a 1/4" jack. Look at the jack used on the Roland units. You need something like that. You also need a way to stop from having cross talk between strings, if you are using piezo pickups. Each pickup will need it's own preamp before it goes to the MIDI converter to convert the impedance. The MIDI unit is expecting very low impedance coils, not very high impedance piezo sensors. Diodes wound clip (distort) the signal, and wont give you any isolation. You wont get an "ohm" (resistance) reading through a diode, and also you wont get a resistance reading on a piezo pickup either. What you are trying to do is pretty complicated, especially if you are unfamiliar with electronics and piezo bridges. You'd be better off to buy a MIDI unit for a nylon guitar.

I own one of those Schatten winders... the older one with the metal case. It's not a bad winder, but it's over priced. It's not worth $350. $200 maybe. It's a bit crudely made... I had to square up the wire guide to the "tower". The motor is a bit underpowered, and while it works fine on 42 gauge and higher, it will barely work on something like 36 AWG. I tried it. It could not wind a usable coil. (BTW, some "Charlie Christian" pickups used 36 AWG. Les Paul Recording pickups were even heavier gauge... I think 24) If you are looking for an out of box experience, the Schatten winder will do it. I bought it for precisely that reason... I didn't have my workshop set up at the time, and didn't have room to build my own winder, or a place to keep it. The Schatten has been working well for me, but as I step up production on pickups, I will be outgrowing it. My next step is to build a CNC controlled winder.

If the LEDs are going into the fingerboard face (i.e. where the position dots are) most of the LED will be buried in the fingerboard. You need to use low profile LED's. The wires will be in a shallow channel on the underside of the board. If you are using a truss rod that installs flush with the top of the neck blank, I'd put a hard veneer between the neck black and fingerboard (such as maple or purpleheart, etc.). I do this on all my necks anyway. You can glue that veneer to the bottom of the fingerboard after your LEDs are in and tested.

Where is the 1/4" jack? On a cable from the pickup? Why not used an enclosed jack and plug a path cord into that. That's neater than either splicing a longer cable onto the wire from the pickup, and you don't have all that cable hanging out. The professional way to do it is add and endpin jack to the guitar. That want detract from the value of the martin. Those old DeArmonds can be valuable pickups, I wouldn't alter it any more than you have to.

I don't think he was trying to solve a problem. If any it was cross talk between strings. Mainly he was as stated in patent 3983778, is making a design that "provides a highly asymmetrical magnetic field for preferentially sensing and generating electrical signals responsive to string vibrations perpendicular to the string plane." He explains in both patents that acoustic instruments reproduce the sound of the vibrations perpendicular to the string plane, as that's the direction the sound board moves. The parallel segment of the vibration doesn't produce movement in the sound board. In 3983778 he states: "the rate of change of magnetic flux in the horizontal direction is much less than the rate of change in the vertical direction. The rate of magnetic flux in the horizontal direction approaches zero." Other parts of both patents deal with "bending". Actually small round pole pieces do indeed cause signal loss when you bend. This is why Fender used two poles per string on bass pickups. The poles are much closer together on guitar pickups, but you can hear it as compared to a blade pole piece. You did say: "Horizontal motion has not been considered in the work above because an examination of the fields produced by FEMM indicated that vertical motion is the dominant effect for the circular pole pieces assumed." See, but what if you are not using circular pole pieces? The whole design behind the Barts, and some other pickups, is in not using circular pole pieces; "The pole pieces have a rectangular cross section. The system further includes planar poletip faces having a planar configuration of an isosceles trapezoid. Sensing coils are disposed around each of the pole pieces. Again, the combination of the rectangular pole pieces and the trapezoidal planar poletip faces provide an asymmetrical magnetic field region surrounding each string of the instrument which preferentially senses and generates electrical signals responsive to string vibrations perpendicular to the plane of the poletip face." If you've even used Bartolini pickups, especially the early Hi-A versions, you can see that he succeeded in getting a very clear almost acoustic like tone from the instrument. That's not to say everyone wants that tone, but I'm posting this info as an example of the way pickup designers manipulate the magnetic field shape to get different tones. Bartolini states: "Above the resonant frequency, the impedance is by the capacitive effects between turns of the coil and between layers in the coil winding. Specifically, the changing current in one turn of the coil influences the current in the neighboring turns of the coil. This effect becomes larger with increasing frequency that the coil behaves as a capacitive reactance with turn-to-turn capacitive leakage to ground. Accordingly, the output signal from the sensing coils falls off rapidly above the self-resonant frequency. Since both the inductance and capacitance of a sensing coil vary linearly with its mean radius, replacing one coil by multiple small coils can reduce the impedance the pickup system by a factor equal to the number of coils and raise the self-resonant frequency by a factor to the square root of the number of coils." You said "Also, the circuit discussion in the last paragraph cannot be applied generally. For example, in a passive system, it is the cable capacitance that dominates (with the volume up), not the inter-winding capacitance." But this isn't true. Ask any pickup maker that pots their pickups in wax and they will tell you it reduces the high end of the pickup. This made no sense to me until it was pointed out the dielectric constant of beeswax is 2.7 - 3.0, and paraffin wax is 2.1-2.5. You would think it doesn't matter with insulated magnet wire, but this isn't the case. Even the insulation type and thickness effects the tone. And we all know that "scatter" winding makes a brighter sounding pickup, and it's assumed this is because the turn-to-turn capacitance is lower. There are many patents dealing with this very thing. In the 1973 patent #3715446, Kozinsky states: "Because of the large coil structure surrounding the six pole pieces, the capacitance of the winding is very high. For example if the six pole pieces are spaced over a two and a half inch, distance , then the coil wound around the six pole pieces would be approximately five inches long. Since capacitance increases directly with the length of the winding and since there are several thousand of such windings for each coil structure, the capacitance becomes very high and causes a serious reduction in its capability of reproducing all of the higher order harmonics and thereby reduces the quality of the sound reproduced by the instrument. Second, because one coil structure is wound around a plurality of pole pieces, rather than around each individual pole piece, the magnetic lines of force produced by the pole, pieces will only cut two sides of the coil structure rather results m low attenuation of all high order frequencies than all four sides. This results in a decreased induced current and therefor adversely affects the sound reproduced by the instrument. This loss is compounded by the fact that the magnetic field is reduced by the square of the distance, between a pole piece and the coil structure."

I asked them a similar question once and got the "acts like a switch" response. It doesn't make sense to me. A pot is just a voltage divider, and it should work as intended as long as it's impedance is large compared to the source impedance. I have an EMG equipped guitar (with 25k pots). I thought about trying some 500k pots to see if the "acts like a switch" statement is true, but I've never actually gotten around to it. I'm not saying it's not true, but I can't seem to figure out why it might be. With audio taper pots, the volume comes up real quick when you use 500K pots with EMG's. It's not the end of the world though. As I said I have a frankenstein guitar that I slapped together real quick, and I used the 500K pots they were on the pickguard. I wanted to try out an old Overlend EMG mini humbucker I picked up. I stuck that and an SA at the neck. I haven't felt the need to change the pots, even though I have a whole box of 25K EMG pots. So I would use the ones they supply, but they will work just fine with higher values.

You can put them anywhere on the instrument you like. Talk about putting them on harmonic nodes is nonsense, because as soon as you fret a note, the harmonics move. Put them where they aren't in the way, and so they look good with the design, and not too close to each other, or too close to the bridge.

Why do you need that particular rod? It's just like the ones from Stew-mac and LMII, and they tell you the dimensions! Their rod isn't any smaller than the standard rods from LMII.

Don't buy your bits from Stew-Mac. Get a pattern bit from a woodworking catalog. You first need to make a pattern. Get some 1/2" plywood and shape that exactly as you want the finished part. Then double stick tape the plastic to the pattern and use the router. I use the router upside down in a router table, or with a real wide base upside down, clamped in a vice. Watch your fingers!