EPIC HIFI • THE DESIGN STORY
I designed the Epic HiFi around one question: could compact speakers deliver bass that makes a subwoofer feel optional and still maintain a HiFi listening experience? I did not want to trade clean detail for low-end impact, or build a speaker that sounded great only when I cranked it. I wanted the same character at quiet listening levels and when the room filled with music. The results blew me away.
That goal sounds simple until you start choosing parts. The drivers need to move enough air for deep bass, yet remain clean enough through the midrange to meet a tweeter. The tweeter has to share that low-distortion character. The cabinet has to reach low without becoming huge or introducing its own noise. Each answer creates a new constraint, and that is how the Epic HiFi took shape.
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The woofers had to stay clean as they moved
Deep bass was only half the challenge. I also wanted the Epic HiFi to keep its character whether I was listening quietly or turning the music up. A driver does not necessarily behave the same way as its cone moves farther and the power changes. If the bass became less controlled when I asked for more of it, I would have missed the HiFi goal even if the speaker reached 30 Hz.
That is why I chose the Dayton Audio Epique E150HE-44. Its split-gap motor keeps the voice coil working in a more consistent magnetic field through its travel, helping it remain linear and control distortion. The 5.5-inch driver also has 14 mm of excursion, giving it the movement I needed for deep bass. Just as important, it could still play high enough to work in a two-way speaker. I did not have to choose bass at the expense of the music above it.
The tweeter had to match that approach
That woofer would not make a HiFi speaker by itself. If the top end became harsh or changed character as the volume rose, the bass would be impressive but the whole speaker would not feel right. So I paired it with the CSS LD25X tweeter. Its XBL² split-gap motor is designed for a broad, flat motor-force curve, keeping the voice coil in its linear range over more of its movement. I wanted the highs to have the same low-distortion, consistent quality I was asking of the woofers.
Now I had drivers that could serve both goals, but they still had to meet cleanly. A speaker can have excellent parts and lose the HiFi experience right where one driver hands the music to another.
Making the drivers sound like one speaker
I measured distortion in both the Epique woofers and the CSS tweeter before settling on the crossover. The tweeter showed rising distortion down around 1.2 kHz, so I used a third-order tweeter section to push those lower frequencies down and crossed the system around 1.6 kHz. The woofers' off-axis response also behaved well at that point. The aim was a clean handoff so that the details in the music survived the transition.
That solved the midrange and treble side of the HiFi question. The bass system had to meet the same standard. Reaching a low number would mean little to me if I could hear the enclosure struggling to get there.
Deep bass had to be good bass
When I modeled the Epique drivers in a compact cabinet, a conventional port looked tempting until I worked out what the tuning required. It would have to be long, making the cabinet harder to keep compact. More concerning for a music speaker, that length could bring port resonance, and the airflow could become audible. I was not interested in bass that measured low but came with noise of its own.
Two eight-inch passive radiators on opposite sides of each cabinet let me pursue the low tuning without that long port. Their opposing movement also helps keep the cabinet steady. This choice served both parts of the premise: extension for music that deserves real low-end weight, and clean bass that does not call attention to the way it was produced. The finished speaker reached an F3 close to 30 Hz—plenty of extension for most of the music I listen to without a separate subwoofer.
The cabinet ended up 20 inches tall, 8 inches wide, and 13.5 inches deep per speaker. That is not tiny, but it keeps the design practical while giving the drivers and passive radiators the enclosure they need. I wanted the bass to feel like a natural part of the speaker, not a trick achieved by making it bigger and noisier.
Giving the bass enough power
Using two Epique drivers per speaker and wiring their dual voice coils this way gives a theoretical 6 dB gain in sensitivity. That makes the speaker easier to drive. I still prefer more amplifier power when I want the bass to really thump.
There was more to this design than I can cover in one article. If you want to see how I worked through the driver choices, tuning, wiring, and crossover, watch the design video below.
Then the design had to become something I could build
I wanted these to be buildable without a CNC machine. I used mine because it was available, but the basic cabinet can be made with a circular saw and a router for the openings. The walnut front baffle was my way of giving the finished speakers a look that matched their sound; it was not a special acoustic ingredient. What mattered was keeping the cabinet geometry, driver positions, and internal construction true to the design.
Even the way I cut and assembled the cabinet served that goal. By insetting the rear baffle, I could make matching side panels and center the passive radiator cutouts on each painted side. A temporarily positioned brace held the spacing during glue-up. I oversized the walnut baffle slightly so I could trim it flush afterward. Those choices did not change the crossover curve, but they reduced opportunities to build the two cabinets differently—which matters when the aim is a consistent stereo pair.
Did the two goals survive the finished build?
Once the drivers were installed and the passive radiators were tuned, I finally got to hear whether the design decisions worked together. The bass had the weight and movement I was chasing, but I was just as pleased that the speaker still sounded clean through the rest of the range. With the SMSL AO200 in the build video, I felt no need to add a subwoofer for my listening. The result blew me away because it answered both halves of the original question, not just the bass half.
Build your own Epic HiFi
The plans include the cabinet dimensions and diagrams, step-by-step build guide, crossover design and wiring, material and tool recommendations, and passive radiator setup. Parts are purchased separately; the current plans page estimates roughly $540 in parts per speaker, with prices subject to change. The plans are a $30 instant PDF download for personal use.
Check current prices and availability for the Epique E150HE-44 woofers, CSS LD25X tweeter, passive radiators, and terminal cup through those links. The plans specify the crossover components and remaining small parts, including the wiring that makes the two-woofer design work.
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