Small and convenient bookshelf speaker production schematic

High frequency probe high frequency line can be customized other specifications

Photocoupler

When it comes to speakers, many people immediately think of large floor-standing models. However, small speakers often don't get the same level of attention, and people usually assume they can't match the sound quality of bigger ones.

But is that really true? Are small speakers inherently inferior in sound quality?

I recently built a pair of compact speakers using two components: the "Silver Flute" YD131-727X 5-inch woofer and the YDQG4-2 tweeter. These are not just any standard parts—they were chosen for their balanced performance and compatibility.

The process of building these small speakers involved several key steps:

Step 1: Choose Speaker Type I opted for a sealed enclosure rather than a ported one. While ported designs offer deeper bass, sealed enclosures provide tighter and more accurate low-end response. For this project, the sealed design was the better choice.

Step 2: Calculate Internal Volume To determine the internal volume of the enclosure, I used the formula: V = 355a⁴ / αf₀²m₀ Where: - V = effective internal volume (in liters) - a = effective cone radius (in cm) - α = stiffness ratio - f₀ = resonance frequency of the driver - m₀ = equivalent mass of the moving system After testing both methods—setting Qoc to 0.7 or adjusting foc to 90Hz—the calculated volume came out to approximately 6.5 liters, which matched the manufacturer's recommendation. This confirmed that a 90Hz minimum resonance frequency was ideal for this setup.

Step 3: Design Speaker Dimensions To avoid standing waves and ensure good aesthetics, I chose a non-proportional ratio of 1.6:1.0:1.1 for length, width, and height. Using this ratio, I calculated each dimension based on the total volume of 6.5 liters. The final dimensions were approximately 23.5cm x 14.5cm x 18.5cm.

Step 4: Crossover Design The crossover frequency was set around 5kHz, considering the frequency ranges of both drivers. The woofer has an impedance of 6Ω, while the tweeter is 8Ω. This difference in impedance required careful matching in the crossover network. I designed a 6dB/octave high-pass filter for the woofer and a 12dB/octave low-pass filter for the tweeter. All component values were selected empirically with minor adjustments for real-world performance.

Step 5: Cabinet Assembly I used solid wood panels for the cabinet. After cutting and gluing the pieces together, I reinforced all joints with wood screws. Once the glue dried, I lined the interior with asphalt and then added a layer of 5cm thick acoustic foam to reduce internal reflections.

Step 6: Finishing Touches After filling gaps with wood putty and sanding the surface smooth, I painted the cabinet three times using a spray paint. I also added speaker grilles made from mesh stretched over a wooden frame.

After assembly, I tested the speakers with an Audio Test CD and found that the frequency response between 90Hz and 18kHz was fairly flat. In actual listening, the sound was clear and natural, especially for pop and light music. While dynamic range wasn’t as strong as larger systems, the combination of tube amplification (using 6N2 and 6P14 tubes) worked beautifully with these small speakers, delivering warm and detailed sound for genres like country and jazz.

Small speakers may not have the power of big ones, but they have their own charm. They’re easy to place on a shelf or in a corner, and they deliver excellent sound quality that brings out the beauty of music. Whether you're a casual listener or a serious audiophile, small speakers can still offer a rewarding experience.