DIY 3D-Printed Portable Bluetooth Speaker — Measured Performance and Design Notes

[Erennurb]

I’ve been working for the past few weeks on a small portable Bluetooth speaker as a personal experiment: how close could I get to objectively “hi-fi” performance from a single full-range driver in a compact enclosure, using 3D printing for the cabinet and modest DSP to refine the response. I thought it might be of interest to ASR given the measurement-oriented focus here.

Design Overview

• Driver: Dayton Audio PC83-8 (3” full-range, 8 Ω)
• Alignment: ~1.5 L enclosure with dual 3” passive radiators tuned to ~70 Hz
• Amplifier: Dayton Audio KABM-30M (25 W mono Class-D, Bluetooth input)
• Power Supply: 3 × 18650 cells (≈12 V nominal) with BMS
• Construction: Fully 3D-printed enclosure (Bambu PETG HF for body, translucent PETG grille, TPU feet and seals via AMS)
• Wall thickness: 4 mm, 25% gyroid infill

The passive radiator alignment was chosen over a ported design due to impractical port lengths at this enclosure volume and target tuning. A light lining of ¼” neoprene foam was added on the rear wall to broaden system Q without overdamping.

DSP / EQ
I applied modest EQ using the Dayton KABX interface, primarily to flatten the response and correct minor driver artifacts:

• High-pass filter at 60 Hz, 12 dB/oct for excursion control
• +1.5 dB low-shelf around 90 Hz for balance
• –3 dB cut at 900 Hz (Q ≈ 2) to flatten mid hump
• +2 dB shelf around 2.8 kHz for presence/vocals
• –2 dB notch at 12.5 kHz to tame treble peak

The EQ is deliberately light: ±3 dB adjustments across most of the spectrum.

Measurements
Taken at 1 m on-axis using UMIK-1 and HouseCurve.

• Low frequency extension: Flat to ~68 Hz, –3 dB at ~63 Hz
• Midrange: ±3 dB from 200 Hz–4 kHz
• Treble: Mild +2 dB plateau at 10 kHz, smooth roll-off above 14 kHz
• Maximum SPL: ~94–95 dB peaks at 1 m, ~88–90 dB continuous before compression

For context, this is notably deeper LF extension than many commercial portables in this size class (e.g., JBL Flip, UE Wonderboom), which typically roll off below 90–100 Hz. Distortion measurements are still pending (will add once I run REW sweeps with a calibrated setup).

Subjective Impressions

Within its size constraints, the system sounds balanced and unforced. Bass is tight and articulate, mids are natural and free from obvious coloration, and the treble is smooth after correction. The coherence of a single full-range driver gives it a pleasing integration across the spectrum, though obviously stereo imaging is absent. Compared side-by-side with some commercial $100–$200 Bluetooth units, the response is more linear and the low-frequency extension superior.

Closing Notes

This build reaffirmed the benefit of getting the acoustics right first (enclosure volume, alignment, radiator tuning), and then using DSP only for refinement. It’s also a good case study for how 3D printing can enable functional loudspeaker designs beyond just cosmetic shells.

I’ll update with distortion and directivity measurements when I’ve gathered them. Curious to hear feedback from this community on potential refinements — particularly on measurement methodology or EQ approach.

I have the 3d print files at https://makerworld.com/en/models/1840687-afterglow-bluetooth-speaker#profileId-1966339
And instructions for build at

AfterGlow Hi-Fi Bluetooth Speaker

AfterGlow Hi-Fi Bluetooth Speaker: Creating a real 3D Printed Hi-Fi Bluetooth speaker that can be made to reflect the style of the person building it

www.instructables.com