The SB Revolution loudspeaker kit by Jeff Bagby
The Revolution began as a project commissioned by SB Acoustics. They wanted a design utilizing the new low-cost Beryllium tweeter and the 5 x8″ passive radiator. A mistake gave you this second version. This kit was originally the “Mini Be” version, but the wrong hole was cut in the test cabinet. Instead of cut for the MW13P woofer, it was cut for the SB15CAC30. Not to let a good cabinet go to waste, Jeff did a version using the Ceramic woofer along with the Be tweeter and SB 5 x 9″ passive radiator.
The original plan called for the Beryllium tweeter, but Jeff found the hew, SB29SDAC fabric unit was a drop-in replacement. This allows you to grab this great system for a price far below the intended design – or add the Beryllium as an upgrade.
The woofer features the ceramic-coated aluminum cone which is naturally white due to the plasma treatment. Allergic to “white” cones? Chose the black, aluminum version. While some will argue there are sonic differences, both models are identical, both electrically and acoustically.
Jeff optimized the crossover in both the frequency and phase domains at the same time. The frequency response is exceptionally flat from 50 Hz up. The two drivers track each other in the relative acoustic phase. They track together in the crossover region and over a very wide bandwidth. The crossover point is at 1.8kHz. The response on-axis measures flat.
How Does it Sound?
The speaker offers a wonderful sense of scale and weight, and bass extension that seems to defy its size. Not many speakers this size can reach into the 40 Hz band with low distortion. Sitting on a pair of quality stands a pair of these small speakers will provide near-full range performance for the majority of music lovers on most of the music they play, without the need for a subwoofer. However, if a subwoofer is used these will combine with it gracefully and allow a fairly low
crossover point to the sub, aiding in helping the subwoofer disappear and provide a greater sense of realism.
The woofer cabinet is .49cu ft or about 14L and measures 8″ wide, 13″ High and 11″ deep (3/4″ material) The original cabinet was 13″ deep, but Jeff found the tuning to be almost identical for a slightly small cabinet. This helps immensely for wood material yield.
Sensitivity is rated at 85dB
What do I Get?
Included in this kit are the full build plans. You can purchase is in two forms, depending on your resources:
The Bare Bones Version:
- 2 x SB Acoustics, SB29SDAC-4 or upgrade to the SB29BAC Dome Tweeters
- 2 x SB Acoustics, SB15CAC30-4 Woofers
- 2 x SB Acoustics, 5 x 9″ Passive Radiators or Port Tubes.
- 2 x Crossover components featuring Cebo & Aydyn capacitors, Lynk resistors, and specified, Air and steel Core Inductors.
Need all the goodies?
The Full Kit Package:
- Input Terminals – There is limited room on the back due to the PR so we give you 4 Binding Post Options.
- All mounting hard hardware (screws)
- Internal damping material
- Color-coded hookup wire
- Optional push-on connectors
- Gasket sealing tape
- MDF boards for mounting the crossover parts.
Choose your Series Capacitors. There are 3 capacitors in the tweeter circuit and we give you 3 great options. As I said, we 3 capacitors, Mundorf options would be pretty crazy, but it can be accommodated if you insist!
Have trouble soldering or reading a crossover diagram? We can assemble them for you at a nominal charge.
Upgrades – Have a favorite input terminal or preferred capacitor brand? Feel free to call or email with your request. We are happy to accommodate you.