Alan, a seasoned DIY audio enthusiast, embarked on an exciting project: constructing bookshelf speakers. With prior experience in transmission line subwoofers, this project aimed to explore full-range audio in a compact design. The goal was clear – to achieve maximum bass extension from a small speaker while maintaining a respectable high-frequency response. This project highlights how readily available components from retailers like Parts Express enable hobbyists to create custom audio solutions.
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The heart of the speaker lies in its driver selection. Initially using Kicker R4c midrange speakers, Alan later upgraded to Dayton Audio RS100T-8 4″ Reference Woofers. The Dayton drivers, sourced from reliable suppliers of car audio parts express, were chosen for their superior low-frequency performance (Fs) and greater excursion (Xmax). The truncated frame version was essential to ensure proper ventilation within the unique enclosure design.
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The enclosure employs a transmission line design, crucial for achieving the desired bass extension. Behind the driver, the line starts at a 3” depth, tapering to a 1” exit. The enclosure, built with 1/2” MDF for the exterior and 1/4” HDF for internal baffles, measures 4” internal width. The 74” line length tunes the speaker to a 1/4 wave at 46 Hz. Assembly involved gluing and clamping MDF and HDF, with clever use of rubber foam to secure 45-degree corners during the process. This intricate design showcases the possibilities achievable with readily available speaker components and some DIY ingenuity.
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Notably, the speaker operates full range without a crossover, simplifying the design and highlighting the driver’s capabilities. Initial testing revealed an echo resonance, effectively eliminated by lightly stuffing the initial section of the transmission line with polyfill. The results were impressive: “amazing” bass extension for a 4” speaker, suitable for relaxed listening, and a wide, non-fatiguing high-frequency image. Alan particularly praised the outstanding vocal reproduction with the RS100 drivers.
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Alan’s journey from SPL competition to sound quality focused car audio is evident in this project. He envisions using these speakers as dash speakers in a future car audio build, demonstrating the versatility of DIY audio and the value of sourcing quality Car Parts Express for custom projects. This bookshelf speaker build serves as an inspiring example for anyone looking to delve into DIY audio and experience the rewarding process of creating high-quality sound with readily available components.
