Nu Series Modular Active Pickups

The Nu Series Modular Active Pickups are hacker friendly, general purpose pickups that can be used in a variety of applications. These are active multichannel pickups with low impedance coils and an integrated single-ended, low-power, low-noise preamplifier for each coil. These low-profile, Neodymium-core pickups are modular and can be used individually or in groups.

nu

Multichannel (8-String) Nu System with Internal Breakout

This is the next evolutionary stage of our flagship multichannel Neo pickup. The Nu sports better crosstalk performance using permalloy ring shields and even lower noise with an improved discrete preamp design. Most importantly, they sound just as good as the originals — same coil, same magnetic structure.

The pickups are designed for multichannel effects 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 can also be utilized for other musical instruments such as the bass guitar, harps, pianos, xylophones, etc. The Nus are perfect for fanned-fret electric guitars (and basses) where the pickup poles are positioned at various angles.

Sound Clips

Here’s a short clip with a “classical” EQ capture of the Cycfi Nu multichannel pickup mounted on a Fender Stratocaster in the bridge position. The strings are panned from right to left, with the low-E at the right and the high-E at the left.

See Sculpting the Tone for details and more sound clips.

Installation Guide

For installation and interfacing, see the latest Nu Multi and Internal Breakout Board Installation Guide.

Frequency Response

Low-impedance pickups have a wide frequency response (full range). Unlike traditional high-impedance passive pickups, there are no big peaks and dips in the response, which to many give the pickup it’s “character”. That should not be a problem since we can always shape the frequency response later on in the signal chain using various tone-shaping methods. The pickup is very rich in harmonics. It has a lot more harmonic content than even the bright, but very noisy Stratocaster pickup. Having a wide and flat frequency response gives you the freedom to sculpt the tone that you want using analog or digital filters. The idea of a low-impedance pickup which imparts very little coloration to the guitar sound is appealing. You get whatever tone you want using appropriate tone shaping EQ rather than a fixed, predetermined guitar tone.

freq-response

Actual Measured Frequency Response

Specifications

Coil D.C. Resistance 400Ω
Coil Capacitance 53.9nF
Wire gauge 46AWG
Number of turns 1300
Flux Density (Sensor at 6mm from pole)
Baseline Stratocaster: 112.17 gauss
Baseline EMG 81: 67.17 gauss
55 gauss
Voltage Output (automated; moderate picking)
Baseline Stratocaster (passive): 484mV peak-to-peak
Baseline EMG 81: 720mV peak-to-peak
748mV  peak-to-peak
Frequency Response 20Hz – 20kHz
Signal to Noise Ratio SNR
Baseline Gibson Les Paul (PAF): 59.57 dB
Baseline Fender Stratocaster (Single Coil): 47.52 dB
73dB
Crosstalk
(Tested at 10.2mm coil spacing, 1mm from string)
49dB: Non optimized
53dB: Active crosstalk cancellation
Output Impedance 10kΩ
Supply Voltage 5V
Supply Current 375μA
Physical Dimensions 15.7mm x 10mm x 7.1mm
(Length x Width x Height)

Nu Capsulenu-capsule-short

The Nu capsule is the most basic modular building block which includes the permalloy shielded pickup and integrated preamplifier. The Nu capsule is intended to be PCB mounted and includes a 5-pin 2mm pitch header connector that can be directly soldered to a PCB, or mounted to a corresponding female header.

GND Ground
V+ 5 V supply voltage (Use a clean, well regulated 5v supply)
O Preamp Output

Technical Drawing

(Click to view PDF)

Schematic

The circuit utilizes Toshiba 2SC3324 low-noise NPN transistors with an exceptional noise figure of 0.2dB (typical). The preamp configuration is a common-emitter amplifier with both emitter feedback and self-biasing collector feedback. The collector feedback ensures that the transistor is always biased in the active region regardless of variations in Beta. The second stage is a simple emitter-follower providing current gain and low output impedance.

(Click to view PDF)


Nu Module

nu-module

FPC

Latching FPC Connector

Individual PCB baseplates for each Nu capsule make it easy to install these miniature pickups. The Nu module includes a PCB baseplate and solder-free Flexible printed circuits (FPC) connector for easier installation and mounting. Shims and EVA foam spacers are utilized for individual module-height adjustment.

Nu-Module-Views

Technical Drawing

(Click to view PDF)

Nu Multi

Nu-Multi-3D

Nu Multis are Nu Modules combined in groups. A laser-cut baseplate mounts a set of Nu Modules as shown in the image above. Notice the use of shims and EVA foam spacers for individual module-height adjustment. Each Nu Module group (1 to 4 modules per group) connects to an adaptor board underneath the baseplate for up to 3 groups (12 channels). Take note of the FPC connectors in the adaptor board (image above) and FPC connections for a single group (4 modules) below:Nu-FPC

Nu Multi Pinout

Nu-Multi-Back

Internal Breakout

The Internal Breakout provides easy access to all the Nu Multi pins using standard header (2.5mm and 2mm) connectors. The small (27mm x 38mm) internal breakout board includes pins for inputs from the Nu Multi and other monophonic sources (up to 12 channels), control voltages for by-wire control of volume, tone, patch (or just about any effect for that matter), ultra-low noise power for both 9v and 5v circuits, and individual outputs.

Audio Channels (Ch1-12) Up to 12 audio channels connect to the multi-channel Nu pickup and any standard monophonic pickup.

    1. Three FPC connector groups connect to up to 12 Nu channels.
    2. Standard EMG-style header connectors connect to up to 4 standard monophonic pickups.
CV Channels Control voltages for by-wire control of volume, tone, patch or control of just about any effect.
Outputs Channel 1-12 outputs
IN Audio (Ch 9-12) or CV inputs (Ch9-15)
VCC 12v power source
9V Ultra-low noise 9v power
GND Power ground.
SGND Signal Ground
NC Reserved (Not Connected)

Schematic

(Click to view PDF)

A single 12v VCC coming from the output pins branches out to two internal power sources. There are two ultra low-noise LDO (low dropout) regulators followed by capacitance multipliers for the 9.3v which powers all audio and control voltage inputs, and another 5.4v supply which powers the Nu. The capacitance multiplier cleans up any remaining noise from the external supply giving you extremely clean power —a must especially when sending the output to extremely high gain stages. That is also the reason for the odd, non-exact voltages (9.3v and 5.4v).

The output pins provide up to 12 channels of audio and up to 7 channels of control voltages (CV). Channels 1 to 8 are strictly audio, which may come from either the multichannel Nu or any other active or passive monophonic guitar pickup. Channels 9 to 12 may either be from audio sources or CVs. Channels 13, 14, and 15 are strictly CVs, which provide a variable 0v to 5v voltage source used for external control of various parameters.

internal-breakoutGnd is power ground. SGd is signal ground. Signal ground is separate from power ground, again, to minimize noise. It also provides an asymmetrical balanced line where the signals are transmitted differentially, but only the hot wires carry the signals. Signal ground is arranged to have the same impedance to ground as any of the channels.

Whilst not strictly required, ideally, the receiving end could provide N+1 impedance matched input buffers, where N is the number of channels, and the +1 represents one more buffer for signal ground. This extra buffer carries the common mode interference that should also be present in the other lines, with the same magnitude, since the impedances are the same. Subtracting this from all the channels should clean the signals of any interference injected through the cables.

Nu sources connect to FPCs (flexible printed circuits) at the left, in groups of 4. Thus, the 8 channels pass through two connectors, while the third is stubbed out. The stub simply shunts unused pins to ground. Audio and CVs connect to 2.54 pitch headers at the right.

Files

Nu Capsule

Schematics Nu_Capsule_Schematic.pdf
Nu_Capsule.sch
Board layout (Eagle) Nu_Capsule.brd
Bill of Materials Nu_Capsule_BOM.pdf
Technical Drawing Nu_Capsule_Drawing.pdf
Nu_Capsule_Drawing.dxf

Nu Module

 Technical Drawing Nu_Module_Drawing.dxf
Nu_Module_Drawing.pdf

Nu Multi

Technical Drawings (PDF) Nu6_Multi.pdf
Nu7_Multi.pdf
Nu8_Multi.pdf
Schematics NuMulti_Adaptor_Board.sch
Board layout (Eagle) NuMulti_Adaptor_Board.brd
Bill of Materials NuMulti_Adaptor_Board_BOM.pdf

Internal Breakout

Schematics Internal_Breakout_Schematic.pdf
Internal_Breakout.sch
Board layout (Eagle) Internal_Breakout.brd
Bill of Materials Internal_Breakout_BOM.pdf
 All Nu design files are contained in this GIT repository: https://github.com/cycfi/nu

Open Source

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

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0
International License
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