Starting off right

This guide will walk you through the complete manufacturing process for the Nosey MEMS Nasometer, from ordering PCBs to final assembly and testing.

Currently, the full PCB manufacturing and assembly has only been tried via JLCPCB. All present information is for their specific ordering steps. If you are using a different manufacturer (or even this one at a later date), please adjust accordingly!

All the files required for manufacture will be available at the GitHub repo after quality control.

Nosey MEMS is designed to be manufactured as simply, as easily, and as cheaply as possible.

  • The PCB is less than 100x100mm (88x60mm) in size, keeping the PCB manufacturing cost low as well as the final device footprint.
  • Assembly is only done on the Top layer, simplifying the process.
  • All components, excluding the XLR3 audio jacks, are assembled for us, minimizing post-assembly additional work.
  • Automatic assembly allows us to pick smaller part packages, lowering the parts cost and allowing for a smaller footprint, albeit with a possible increase in difficulty for manual rework.
  • The use of MEMS microphones allows us to circumvent a lot of obstacles in microphone design and manufacture—from sourcing parts to soldering—while keeping the cost low at an acceptable frequency range.

The Process of Acquiring a Nosey MEMS

Step by step.

Getting the Production Files

Go to Downloads and download the production folder. Inside there are:

  • the .zip file containing the PCB Gerber files,
  • the bom.csv file containing the Bill of Materials, and
  • the positions.csv file containing the component placements.
All three are critical for manufacture.

Find a PCB fabrication and component assembly manufacturer and follow the general ordering process. The rest of the guide will be referencing the process of a particular manufacturer.

PCB Fabrication

Upload the .zip Gerber files. Choose fabrication options to your liking.

Standard fabrication options are in this Table 1:

Table 1. PCB Fabrication Settings
Spec Value
Dimensions (if using the source PCB) 88 mm × 60 mm
Material Type FR4 TG135
PCB Thickness 1.6 mm
Layers 2
Surface Finish HASL (with lead)
Outer Copper Weight 1 oz
Via Covering Tented
Board Outline Tolerance ±0.2 mm

Bill of Materials

The list of the chosen components for the first assembly test run can be found in Table 2.

Table 2. Bill of Materials for assembly.
Component Designator Footprint JLCPCB Part #
47R R13, R14, R6, R7 0805 C17714
470R R15 0805 C17710
3k R10, R2, R3, R9 0805 C17661
15k R1, R11, R12, R16, R17, R4, R5, R8 0805 C17475
10nF C15 0805 C1710
22nF C10, C4, C5, C9 0805 C1729
2.2uF C1, C11, C12, C14, C6 0805 C377773
10uF C16, C17, C19 0805 C15850
47uF C13, C18, C2, C3, C7, C8 CP_Elec_6.3x7.7 C2887275
1N4148 D1, D2, D4 D_SOD-323 C2128
1SMA4746A D3 D_SMA C330245
OPA1652 U1, U2 SOIC-8_3.9x4.9mm_P1.27mm C30025
PJ71K30SC U3 SOT-23 C411738
NA-FFA381-A10-1 MK1, MK2 2.75x1.85x1.0mm Top Port C50275774

These are the chosen components available at the time (October2025).

Please adjust according to your need and your manufacturer.

Assembly Instructions

After confirming the BOM file, the component placements need to be verified next. Sometimes, the orientation of components may be wrong. Carefully inspect and make sure all polarities are correct. The assembly placement for the first run is shown in Figure 1.

Nosey MEMS PCB top assembly component placements
Figure 1. Component orientation and placement visualization during the ordering process.

NOTE:

If the manufacturer's viewer doesn't show the model for the MEMS microphones (MK1, MK2), the manufacturer should resolve this. Otherwise, a soldering station and advanced SMD soldering skills will be needed to solder on the MEMS microphones.

If a component is placed in the wrong orientation, the manufacturer typically runs a Design for manufacturability (DFM) analysis to catch such mistakes. While this provides a useful safety net, it's best practice to ensure all components are oriented correctly before submitting the design.

Nosey MEMS devices as received from manufacturer
Figure 2. Nosey MEMS PCBs as received from the manufacturer, fully assembled and ready for XLR jack soldering.
This concludes the ordering process. If all went well, your Nosey MEMS is being manufactured and you will receive it fully and properly assembled. When it arrives, move to Soldering the XLR jacks.

Soldering

The only components that require soldering upon receiving the assembled board are the two XLR3 audio jacks.

  • Place the audio jacks in their designated positions on the PCB (J1, J2), as shown in the images below
  • Solder all pins with appropriate solder and flux
  • Verify all connections are mechanically and electrically sound
  • Proceed to Testing and Verification
XLR3 jack placement on Nosey MEMS PCB
Figure 3a. XLR3 jack placement on the PCB (J1: L-Nasality, J2: R-Orality).
Properly soldered XLR3 joints on Nosey MEMS
Figure 3b. Completed solder joints. All pins should have smooth, shiny solder fillets.

Note: The silkscreen label "Nosality" visible in the images was corrected to "Nasality" in the design files, but this typo was caught after the boards were sent to manufacturing. Future revisions will display the correct spelling.

This concludes the soldering process. If all went well, the Nosey MEMS is now ready for testing. For optional modifications, see Modifications below. Otherwise, proceed to Testing.

Modifications

The following modifications are optional and may be added in future revisions of this guide.

Jackless Nosey MEMS

If sourcing XLR3 jacks is difficult or not necessary for the application, audio cables can be soldered directly to the PCB pads. Additional strain relief should be added (e.g., zip-ties to the 3D-printed housing) to prevent damage to solder joints from cable movement.

Figure and 3D-printed cable adapter design to be added.

Shield to Ground Connection

Connecting the cable shield to ground is a debated topic in audio applications. This modification will be tested and documented in a future update with measured results showing any impact on noise floor and interference rejection.

Measurement results and implementation guide to be added.

5V Operation

For advanced users only. The Nosey MEMS can potentially be modified to operate on 5V instead of the standard phantom power supply. This requires circuit modifications and is only recommended for users experienced with analog audio circuit design. Details can be found in the schematics file.

Schematic modifications and performance comparison to be added.

Testing & Verification

How to test your completed device to ensure proper functionality.

  • First, visually inspect the board. Is it neat? Is it clean? Are all the parts neatly placed and soldered? Are any crooked? Are all component making electrical contact? Does any component look damaged? Are all the polarized components (diodes, capacitors, amps) correctly oriented?
  • Second, turn off Phantom power (48V) and, provdided the board is up to standard, connect only one of the two channels the Nosey MEMS to an audio capture card with a shielded balanced XLR cable. Verify there are no sounds coming from the Nosey MEMS, as it is not yet powered.
  • Third, set the gain to zero before turning on Phantom power (48V).
  • Fourth, slowly increase the grain, making sure there is no feedback or irregular sounds, try talking into the MEMS microphone of the connected channel. You should hear yourself clearly, with no distorsion, delay or artefacts.
  • Fifth, repeat the process for the other channel and verify that both are working correctly and equally well.
  • Sixth, congratulations on your working Nosey MEMS!

If the verification process was successful, move on to calibration of the device, or to 3D Printing the parts. If the verification failed, try Troubleshooting.

Troubleshooting

Common issues and how to resolve them.

PCB Visual Inspection

  • Check overall board cleanliness and neatness of component placement
  • Verify all components are properly seated, straight, and free from physical damage
  • Confirm correct orientation of all polarized components (diodes, electrolytic capacitors, ICs)
  • Look for any bent pins, damaged traces, or signs of thermal stress

PCB Electrical Inspection

  • Verify phantom power is enabled and measures 48V at the XLR connector (Test Pad TP4)
  • Measure Vcc voltage supply — should read approx. 18V (Test Pad TP5)
  • Measure V/2 bias voltage — should read half of Vcc, approx. 9V (Test Pad TP6)
  • Check for any output signal from the op-amps (Test Pads TP1 for L/Nasality and TP2 for R/Orality channel)
  • Inspect all solder joints for proper flow and electrical contact—look for cold joints or bridged connections
  • Examine PCB traces for damage, lifted pads, or unintended continuity between nets
  • Use a multimeter in continuity mode to check for shorts between power rails and ground

Audio Chain Verification

  • Confirm audio interface is powered on, connected to computer, and recognized by the system
  • Test XLR cables and connectors with a known-good microphone to rule out cable faults
  • Verify Nosey MEMS nasometer is properly seated and making good electrical contact
  • Set audio interface gain to minimum (0dB) and ensure channel is unmuted
  • Confirm correct input/output routing in your DAW or REW software
  • Check that phantom power is reaching the microphone through the entire signal chain (Test Pad TP4)