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The Nu modular single-string pickups are hacker friendly, general purpose pickups that can be used in a variety of applications. These are active pickups utilizing low impedance coils, Permalloy ring shields to minimize crosstalk, and an integrated differential, low-power, low-noise preamplifier for each coil. These small pickups are modular and can be used individually or in groups.

The pickups are designed for multichannel processing — one for each string (distortion, EQ, compressor, delay, pan, pitch-shift, etc). Such extensive processing is now possible due to advances in digital signal processing and the proliferation of multi-channel audio interfaces and multi-track audio software.

These modular pickups are not just for guitars. Nus are also successfully utilized in other musical instruments such as the bass guitar, cellos, harps, pianos, xylophones, etc.

Features

  1. Permalloy ring for improved electromagnetic isolation, better string focus and crosstalk reduction.
  2. Low noise discrete/Op Amp hybrid differential preamplifier for improved immunity to electrostatic noise.
  3. High dynamic range, expanded power supply range from 5v up to 18v. 
  4. Instrument-level.
  5. Low output impedance with a 17 mA current drive capability.
  6. Rail-to-Rail Output.

Frequency Response

The Nu Series active polyphonic pickups have a uniform frequency response from 20Hz to 20Khz. The sound is very clean with lots of overtones and crystal clear highs. The low impedance coils give the pickups its characteristic wide bandwidth.

Unlike traditional high-impedance passive pickups, there are no big peaks and dips in the response. Such a wide and flat frequency response gives you the freedom to sculpt the tone using analog or digital filters. The low-impedance pickup imparts very little coloration to the guitar sound. You get whatever tone you want using appropriate tone-shaping EQ rather than a fixed, predetermined guitar tone.

Actual Measured Frequency Response

Sound Clips

See Sculpting the Tone for details about the sound clips. The multichannel recordings take advantage of the stereo field to great effect. For best results, put on a good set of headphones or better yet, have your reference monitors ready, or a good HiFi stereo system. Cheap earphones or laptop speakers won’t do this justice, please don’t bother using those!

Here’s a short clip: Vale Vanezolano no.3 (by Antonio Lauro) recorded using “classical” EQ capture of the Cycfi Nu multichannel pickup mounted on a Fender Stratocaster in the bridge position. The strings are panned with the low-E center, A at 3 o’clock, D at 10 o’clock, G at 4 o’clock, B center and high-E at 9 o’clock. Listen to how the notes seemingly chase each other in the stereo field.

Here’s a short composition: Thousand Paths (Joel de Guzman 2014). This one is mixed to mono using the EMG-81 EQ capture before applying distortion and amp simulation.

Recuerdos de la Alhambra —A classical guitar piece composed in 1896 in Granada by Spanish composer and guitarist Francisco Tárrega performed on a Fender Stratocaster equipped with the Nu multichannel pickups, again with a “classical” EQ capture.

Pinout

The Nu capsule includes a standard 2-pin and 3-pin 2 mm pitch header connectors for power and signal
GNDGround
V+5v to 18v supply voltage. Reverse polarity protected (Schottky diode).
(For optimum performance, use a clean, well-regulated power source)
OutPreamplifier Output

Wiring Examples

The Nu capsules are very easy to use. These are self-contained active pickups. There are three pins, power (anything from 5v to 18v), ground, and output (signal). Here are some basic wiring diagram examples. The Nu capsule includes reverse polarity protection for the supply pins, so you do not have to worry about damage due to incorrect wiring.

Basic Single Pickup

This is the simplest wiring possible for a single pickup. Just connect to any clean power supply, such as a 9v battery and connect the output to your amplifier, mixer or audio interface. The example below makes use of the stereo jack socket ring contacts to switch power. When a mono jack is plugged in, the battery’s negative terminal gets connected to ground, thereby powering the capsule. Power is only applied as long as a plug is inserted.

Quad Setup

Here’s an example for a quad (4 channel) setup using 4 Nu capsules routed to 2 stereo outputs. Each stereo jack carries the output of two Nu capsules. The Nu capsules are modular. This example can extend to more pickups as needed. We also provide out-of-the-box solutions for a better user experience. For multi-channel solutions involving 6 or more audio channels, check out the Nu Multi Series, specifically the Nu Multi 6Nu Multi 7 and Nu Multi 8, as well as the Nu Multi 6 acoustic. And for easier connectivity to audio interfaces, digital mixers, surround amplifiers, etc., check out the Nexus.

Quad Setup Mixed

You can passively mix the outputs by adding a 5kΩ to 10kΩ summing resistor to each output. Simply tie all outputs using the summing resistors as presented in the example diagram below. This example mixes the outputs of two capsules to the left channel and the other two to the right channel. The individual resistor values can be adjusted to balance the mix. It may even be possible to have individual pots per input to give you better control.

Take note that this scheme is only recommended for use with musical instrument amplifiers with high input impedance >100kΩ (e.g guitar amplifiers).

Note on mixing: Typically, each output can passively mix 2-3 inputs. It is not advisable, to have more than 2-3 inputs summed for each mixed output, but be aware that with this simple passive mixing scheme, each additional input will attenuate the signal by the number of channels added and so you will have to add some gain, which will also increase the noise. Also, take note that you will introduce cross-talk with such a passive mixing scheme and is therefore not possible to have both mixed and individual outputs at the same time. For that matter, it is better to use an active mixer (as opposed to passive). But please keep in mind that the Nu pickups are designed for multichannel processing. For high-gain applications, mixing the outputs before high gain stages is not advisable. It is better to use a mono pickup if you intend to simply have a mono mix anyway. If you really must mix the outputs before high gain stages, it is essential to incorporate a noise gate or downward expander per channel before mixing the outputs.

Tip: You can directly tie the outputs of one or more Nu capsules to the output of traditional monophonic active pickups such as the EMG-81. Active pickups already have passive mixing resistors (typically 10kΩ). You can passively mix the Nu capsules output by adding 10kΩ summing resistors to each Nu output and tying the ends to the output of the monophonic active pickup. Adjust the individual resistor values to balance the mix.

Connectivity

The Nu capsule includes a standard 2-pin and 3-pin 2 mm pitch header connectors for power and signal. Direct soldering or mounting to a corresponding female header to a base PCB is possible. Ideally the capsules are mounted to a base PCB like that shown in the left image. Alternatively, you can use female header connectors like that shown in the middle image below to connect, solder-free, to the Nu capsules as shown in the right image. These connectors are fairly easy to get. There are some links in the Further Reading section at the bottom of this page where you can buy these female header connectors.

Technical Info

Preamp Schematic

Dimensions

Specifications

Coil D.C. Resistance320-350Ω
Coil Capacitance54pF
Coil Inductance12mH
Wire gauge46AWG
Number of turns1300
Magnetic CoreNeodymium with Iron
Frequency Response20Hz – 20kHz (extends beyond 100kHz)
Resonance Frequency198kHz
Voltage Output (Note 1)580-740mV peak-to-peak
Crosstalk (Note 2)49dB: Non optimized
53dB: Active crosstalk cancellation
Output Impedance10kΩ
Supply Voltage5v to 18v
Output Voltage SwingRail-to-Rail
Output Current Drive17 mA
Quiescent Current Consumption450µA
Dimensions18mm x 10mm x 7.14mm (L x W x H)
Note 1Automated; Moderate picking
Baseline Stratocaster (passive): 484mV peak-to-peak
Baseline EMG 81: 720mV peak-to-peak
Note 2(10.2mm coil spacing, 1mm from string)

Open Source

This Project is entirely Open Source. The designs (schematics, PCB layout, software, bill of materials, CAD drawings) are freely shared and 100% free, under the Creative Commons Attribution-ShareAlike 4.0 International License. Source code is distributed under the MIT License

Hardware design files licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Software source code distributed under the MIT License.

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