I’ve reviewed some more guitar pickups switching patents lately, and most if not all of the ones I’ve seen suffer design flaws that generally cause them to fail in the marketplace, for some of the following reasons:
- They almost never show in the Figures all the circuit topologies that the switching configurations produce, and thus never discover all the duplicate circuits and circuits with null outputs. This often leaves the user with a lot of switch combinations that produce exactly the same tones, or no tones at all.
- They don’t acknowledge that the human ear cannot tell the difference between a signal and its inverse phase, without a separate reference. Thus the signals like N B and –N+B are often wrongfully counted as separate tones.
- They don’t acknowledge that the coils of humbuckers are so physically close together (about the 16th to 32nd harmonic) that, even if they produced separate signals, they produce virtually the same signal. Never mind that they share the same magnetic circuit and are magnetically coupled, like an audio transformer. I have even used a HB with a signal generator as an audio transformer to test a preamp circuit. Not very efficient, but it produced a signal. So often every combination of one coil each from 2 humbuckers is wrongly counted as a separate tone, ignoring duplicates. Not counting any series and parallel combinations, 2 humbuckers produce exactly 2 single-coil tones (N and B), 2 humbucker tones (NN and BB), and two 4-coil tones, (NN+BB and NN-BB). Out-of-phase combinations in the same humbucker, like Nn-Ns or Bn-Bs, where n and s are the north-up and south-up coils of the humbuckers, produce virtually null signals.
- They don’t acknowledge that the only tonal difference between a series and parallel combination of two pickups or coils comes from the interaction with the load, namely the tone pot circuit and the volume pot, and the guitar cable and amp input. A lower impedance load causes the higher-frequency tones to roll off at a lower frequency than a higher impedance load. So when a pickup or coil feeds directly into a preamp that has a fixed impedance, there is no difference in tone unless the series-parallel switching is done before the preamp. And if the preamp has a very high-impedance input, then tonal difference between series and parallel pickup coils switched before the preamp will be well above human hearing.
- They don’t verify, by any kind of spectral measurement, that all the switch combinations actually produce audibly separate tones. They often falsely assume, without measurement and verification, that every different switch combination must produce a different tone, the more the better. Then, without ever having mapped what tones go with what switch combinations, they leave it all to the user to figure out. Then, to all that complexity producing such small results, they add the cost of more electronic parts.
- And has anybody seen a guitar with digital signal processing sweep the market?
Small wonder that the 3-way and 5-way switches are still so popular, and make up the bulk of the market, even if they are 50 years or more old.
© 2018 Don Baker dba android originals LC, Ph.D retired