35cm parabolic dish for wildlife recording

This is a 35cm parabolic dish designed from scratch for bird and wildlife sound recording, centered around the Rode VideoMicro microphone. The goal of this project was to create a high-gain, budget-friendly alternative to professional equipment. It was field-tested during the 2026 Grabatón (a bird recording marathon) with excellent results for a "quick one-week project." It works perfectly with the Merlin Bird ID app (note: your phone needs a physical 3.5mm jack or an adapter to attach the microphone).

Technical Specifications

• Diameter: 350 mm

• Focal Length: 87.5 mm (f/D = 0.25)

• Cutoff Frequency: ~1,000 Hz (calculated)

• Maximum Gain: ~25 dB @ 8 kHz (calculated)

• Microphone: Built for the Rode VideoMicro, but adaptable to other small cardioid microphones of similar size. (You may need to modify the center hub to ensure the sensitive element is positioned exactly at the dish's focal point).

Bill of Materials (BOM)

In addition to the 3D-printed parts, you will need:

• Support Rods: 3x 6mm diameter aluminum rods (Length: 165 mm).

• Hardware (Preferably stainless steel):

  • 16x M2 x 8mm screws, nuts, and washers for segment assembly (Zip-ties were tested but were not sturdy enough).

  • 4x M3 x 8mm flush head screws and nuts to attach the handle to the dish.

• Surface Finish: High-gloss clear coat to seal the inner surface and improve high-frequency reflection.

• Microphone: Rode VideoMicro with its TRS to TRRS adapter (if using with a smartphone) and the windshield/DeadCat. You will likely need a 3.5mm cable extension as well.

• Cable Management: Velcro straps and automotive (cloth) tape to route the cabling without transferring mechanical noise.

Printing Instructions

• Material: PETG is highly recommended. PLA will not withstand long hours under the sun or inside a vehicle. ABS and ASA may present warping that causes poor joint alignment, deforming the parabolic shape.

• Layer Height: 0.15mm or less (the lower the better for sanding and acoustic performance).

• Walls/Perimeters: 4 or more. (Increased rigidity helps sound waves bounce more efficiently).

• Infill: 25% or higher.

• Infill Pattern: Gyroid.

• Supports: Yes, "touching buildplate" only. The strut mounts will need support during printing.

Please see the attached images for the recommended printing orientations.

Assembly Guide

1. Dish Assembly: Join the 4 main segments using M2 screws/nuts. Each rib joint has a side with recessed holes for the nuts. The washer and bolt should be inserted from the opposite side.

2. Handle: Insert the M3 nuts into the back central part of the dish and attach the handle. This provides extra rigidity before treating the surface.

3. Sanding: For best results, sand the mating surfaces with 150 and 320 grit wet sandpaper to ensure a perfect fit.

4. Surface Treatment: Carefully sand the reflective surface to improve sound bouncing. Use water to keep the parts cool if using power tools—excessive heat can deform the parabolic curve! Seal any porous areas with a high-gloss clear coat.

5. Support Structure: Insert the 3 aluminum rods into the rim sockets and connect them to the central hub. The parts are flexible enough to allow assembly with the dish fully built, but handle with care.

6. Alignment: Ensure the microphone sits at the bottom of the hub (or the capsule is positioned exactly 87.5 mm from the bottom center of the dish). I designed a retainer ring to secure the microphone but didn't use it, the fit was perfect.

7. Cable Management: Secure the cabling to one of the rods. Use cloth tape to prevent rigid contact between the cable and structural parts to dampen vibrations and collisions.

Field Tips

• Due to high directivity at high frequencies, move the dish slowly. The "sweet spot" for bird trills is very narrow.

• Always use a furry windshield to prevent turbulence inside the dish.

• I selected olive green filament for concealment. Birds generally don't like bright objects pointed at them!

License

This project is licensed under Creative Commons (4.0 International) Attribution-ShareAlike. Feel free to remix and improve, but please share your modifications with the community! Original .F3z and exported STEP files included.