DIY Compact 2-Way Bookshelf Speaker using SB Acoustics SB12PFCR25-4 & SB26ST-C000-5

Build a compact high-fidelity 2-way bookshelf speaker using the SB Acoustics SB12PFCR25-4 woofer and SB26ST-C000-5 tweeter. Follow the complete cabinet design, crossover development, measurements, and listening tests.

DIY SPEAKERS PROJECTS

Shravanth Vanga

7/25/20262 min read

Impedance

The impedance charts are electrical measurements of the loudspeaker’s resistance vs frequency.

Designing a loudspeaker is much more than placing two drivers inside a wooden box. Every dimension, every crossover component, and every measurement contributes to the final listening experience.

In this project, we set out to design a compact two-way bookshelf speaker that delivers accurate sound reproduction, excellent imaging, and remarkable clarity while remaining practical for desktop, bookshelf, and small room listening.

Instead of relying solely on simulation software, this speaker was developed through a combination of engineering calculations, prototype testing, acoustic measurements, and extensive listening sessions.

This article documents the complete development process—from selecting the drivers to the finished loudspeaker.

Why We Chose These Drivers

For this project, we selected:

SB Acoustics SB12PFCR25-4 4-inch Paper Cone Midwoofer
SB Acoustics SB26ST-C000-5 26 mm Soft Dome Tweeter

The SB12PFCR25-4 offers a natural paper cone, long linear excursion, low distortion motor design, and smooth midrange performance. It has a nominal 4 Ω impedance, sensitivity around 87.5 dB (2.83 V/1 m), and an Fs of 58 Hz, making it well suited for compact vented or sealed bookshelf enclosures.

The SB26ST-C000-5 complements the woofer with a lightweight 26 mm fabric dome, optimized damping, controlled motor system, and smooth off-axis response. It is rated at 91 dB sensitivity with an 80 W power handling specification when appropriately high-passed.

Together, these drivers provide an excellent balance between detail, tonal accuracy, and affordability.

Cabinet Drawings & Construction

MDF Thickness used - 14.5mm
Cabinet Dimensions:
- Width: 160mm
- Height: 260mm
- Depth: 220mm
All cabinet panels were CNC machined to achieve accurate dimensions and perfectly aligned driver openings.

Port - 25mm dia X 90mm Length