Bookshelf Desktop Speaker enclosure

This is the third and most refined version of my quest for a high-fidelity, 2-way active bookshelf speakers.

These speakers are Active, meaning the amplification is built into the speaker enclosure. The audio source you connect does not need to be amplified—just send a standard line-level signal (like from a phone, PC, or DAC) to the speaker.

These speakers deliver an incredible audio experience with strong, tight bass, powerful mid-tones, and crystal-clear highs. I’ve spent countless hours not only refining the enclosure design for optimal acoustics but also fine-tuning the Digital Signal Processor (DSP) to achieve the sound profile I personally prefer. Using this method you do not need to build crossovers.

The internal chambers are specifically designed and tuned for drivers:

- Subwoofer: Tang Band W3-1876S - Full-range Woofer: Dayton Audio Reference RS100P-4 The custom-designed base features dedicated recesses to discreetly house the active components: a 4-channel amplifier (XH-M180) , an ADAU1701 DSP , and a DC-to-DC buck converter (12V to 5V). The base also contains all the necessary input/output connections (RCA, mini-jack, and power).

3D Printing Specifications

- Infill Density: An infill density of 50% was utilized. Based on structural analysis, this density provides adequate rigidity and material efficiency, and increasing it further is not deemed necessary for optimal performance. - Support Structure: Build plate adhesion support was enabled during the printing process. This support is primarily required to successfully form the recessed features designed for drive mounting. - Build Plate Surface: A smooth build plate is strongly recommended to achieve a smooth finish to the front of the enclosures. Wiring and Acoustic Dampening

- Internal Wiring: 16 Gauge Silicone Wire was selected for connecting the drivers to the amplifier. Wires were soldered directly to the drivers, paying close attention correct polarity! - Driver Chamber Acoustic Treatment (Mid-High Frequency): - All internal surfaces of both driver chambers were lined with 20 mm self-adhesive sound-proofing foam to manage reflections. - The upper chamber received additional internal dampening: clean rags were strategically placed for bulk deadening. The remaining void (approximately 70 mm deep behind the driver) was filled with a substantial quantity of lambswool to provide optimal acoustic absorption. - Subwoofer Chamber Acoustic Treatment: The subwoofer chamber was treated exclusively with the 20 mm self-adhesive sound-proofing foam on its internal walls, ensuring the rear port remained completely unobstructed for proper bass reflex function No other dampening was used. Sealing and Assembly

- Rear Cover Sealing: CT1 self-adhesive glue was used to secure the back covers to the chamber enclosures. This product provides a reliable, robust, and airtight seal, which is critical for maintaining acoustic integrity. - Driver Gaskets: Gaskets were custom-created using 1 mm thick silicon matting and installed between the front drivers and the enclosure surface. Achieving a positive seal here is essential to prevent air leaks (chuffing) when the system operates at elevated volumes. I have tried to provide all the information and settings needed for you to recreate this setup. I even include the sound profile/DSP settings (you will need sigma studio software (free to use https://www.analog.com/en/resources/evaluation-hardware-and-software/software/ss_sigst_02.html ) should you wish to match my preferred tuning!

DSP profiles are attached.

Materials

Electronics and Drivers

Component Quantity (Per Pair) Notes

Full-range Woofer 2 Dayton Audio Reference RS100P-4

Subwoofer 2 Tang Band W3-1876S

Amplifier 1 XH-M180 50W x 4 (TDA7850 chip) 12V Amplifier. Used to power both drivers in each speaker (4 channels total).

Digital Signal Processor (DSP) 1 ADAU1701 DSP board. Essential for tuning the crossover, EQ, and time alignment.

Buck Converter 1 DC to DC Buck Converter (12V to 5V). Used to power the DSP or other components if needed.

Power Supply 1 DC Power Supply (Amperage depends on desired maximum volume).

USB to serial Emulator 1 This is the communication bridge between the software and the DSP board.

Capacitor 1 OJACK 1000uF 16V 10X17mm Capacitors 1000 MFD 16 Volt 0.39x0.67 Inch ±20% Aluminum Electrolytic Capacitor ( Goes across the positive and negative power supply for amp

Connectivity and Control

Component Quantity (Per Pair) Details / Use

RCA Female Panel Socket 4 2 per speaker. Used for the stereo audio input and/or to connect the two speakers together (Interlink).

DC Power Socket 1 Panel-mount socket for main power input.

Stereo Mini Jack Socket 1 Panel-mount socket for easy audio input from devices like phones or PCs.

Push Button Switch 1 Prewired Latching Stainless Steel Push Button Switch for hole size. Used as the main power ON/OFF switch.

RCA Interlink Cable 1 RCA Cable to connect the two speakers. Length varies based on setup.

Aux Cable 1 Mini-jack to Mini-jack cable or equivalent for connecting your un-amplified audio source (phone, PC, DAC, etc.).

Screws 48 Black m4 x 12mm (for drivers)

Screws 8 M4 x 16mm (for screwing chambers together)

Screws 22 M3 x 16mm (chamber covers)

Acoustic and Wiring Materials

Component Quantity (Approx.) Details / Specification

Wiring   16 Gauge Silicone Wire (Soft and Flexible).

Sound-proofing Foam   Self-Adhesive Sound-proofing Foam.

Gasket Material   thick silicone matting (used to make custom driver gaskets).

Deadening Material   Lambswool, plus lint-free rags for the upper chamber.

Sealing Glue   CT1 or equivalent self-adhesive glue/sealant for the back covers.

Boost Me I offer this model completely free. It is a one of a kind and only available on MakerWorld. If you found this as much fun and as rewarding as me then please give me a boost and maybe leave a comment. Many thanks