| Designer | Type | Build | Size |
|---|---|---|---|
| SB Acoustics | 3-way, 10" woofer, bass reflex (front slot port), sealed midrange chamber | You build the crossover and cabinet from SB's schematic and drawings | 610 mm tall |
Short answer: the Rima is the smaller sibling of SB Acoustics' Gema: the same retro-styled 3-way layout, with a 10" woofer, a 4" paper-cone midrange in a small sealed chamber and a 1" soft-dome tweeter, in a 610 mm tall birch-ply cabinet with a slot port across the front. It's one of SB's newest kits (the manual is dated July 2026). There's no ready-made cabinet or assembled crossover for it from us at the moment, so for now the Rima is a full build: you make the cabinet from SB's drawings and the crossover from SB's schematic.
A quick note before we start: we haven't built or listened to the Rima. This is an overview of what's in the kit and what's involved, not a review. Everything about how it's designed and how it performs on paper comes from SB Acoustics' own page, manual and drawings.
What SB says about it
SB describes the Rima as carrying the Gema's 1970s design cues and acoustic approach in a smaller enclosure, with a footprint suited to modern living spaces. The design notes SB highlights:
- A 10" SB29NRX75-8 woofer, chosen for its linearity and low distortion.
- A 4" SB12NRX25-8 paper-cone midrange covering 500 Hz to 3 kHz. SB points to its low moving mass and smooth response.
- The same 1" SB26STAC tweeter as the Gema, with a die-cast aluminium faceplate, an optimised rear chamber and a full copper cap.
- The Gema's construction approach: a well-braced cabinet with a front-firing slot port tuned to 30 Hz and a sealed 3 L midrange chamber, in 15 mm and 18 mm birch ply.
SB's placement starting point: 2 to 3.5 m between the speakers, moderate clearance from side and rear walls, raised 20 to 25 cm on a stand or plinth, tilted back 5 to 6° with a slight toe-in. As with the Gema, the left and right cabinets are mirror images.
SB's published specs
| Rima | |
|---|---|
| Tweeter | 1" SB26STAC-C000-4 soft dome |
| Midrange | 4" SB12NRX25-8 paper cone, sealed 3 L chamber |
| Woofer | 10" SB29NRX75-8 |
| Crossover frequencies | 500 Hz and 3,000 Hz |
| Frequency range | 33 Hz to 24 kHz |
| Sensitivity (2.83 V/1 m) | 84 dB |
| Nominal impedance | 8 Ω |
| Max SPL | 105 dB |
| Recommended amplifier | 100 to 200 W |
| Enclosure | Bass reflex, 41.6 L for the woofer, front slot port tuned to 30 Hz |
| Cabinet | 15 mm and 18 mm birch plywood, 610 x 363 x 305 mm (H x W x D) |
| Weight | 21.8 kg per speaker, fully assembled |
All figures are SB Acoustics' own. Its website and manual agree on every one of them.
Rima or Gema?
The Gema is the bigger sibling: a 12" woofer in a 720 x 430 x 360 mm cabinet, rated at 87 dB and 6 Ω, with SB recommending 50 to 200 W. On paper the Rima trades some sensitivity for a smaller box: it's 3 dB less sensitive and SB asks for a stronger minimum amp (100 W). SB publishes the Rima as drawings and a schematic only, with no ready-made cabinet or assembled crossover.
The parts
Each speaker uses one of each driver. Each link shows today's price:
| Part | For a pair |
|---|---|
| SB29NRX75-8 10" woofer | 2 |
| SB12NRX25-8 4" midrange | 2 |
| SB26STAC-C000-4 1" tweeter | 2 |
Then add:
- Crossovers: built yourself from SB's schematic (parts below).
- Cabinets: built yourself from SB's drawings, plus damping, binding posts and terminal panels.
SB's plans and the drivers for the Rima, in one place: SB Acoustics Rima speaker kit, plans and drivers.
What's involved
Building the crossover
Per SB's schematic, the Rima crossover is 11 parts: three resistors, four capacitors and four inductors. The biggest part is a 4.7 mH inductor on the woofer. Note: SB's schematic marks the midrange as reverse polarity. That's deliberate. Follow the schematic, not your instincts. With only 11 parts it's a manageable first 3-way crossover if you're comfortable soldering. Passive crossovers explained covers layout and parts.
Building the cabinet
SB's 12-page cabinet drawing covers every board. Smaller than the Gema, but still a proper project:
- Two thicknesses of birch ply (15 mm and 18 mm), as SB specifies.
- A sealed 3 L midrange chamber with an angled internal panel, plus an internal brace.
- A full-width front slot port, drivers recessed flush, and mirrored left and right baffles.
The drawings allow for a painted finish; SB's own pair is in walnut veneer. Keep the internal volumes (41.6 L and 3 L) and the port exactly as drawn: the crossover was designed around this cabinet. Building the cabinet covers the techniques.
Putting it together
Like the Gema, the Rima manual has no step-by-step section, just specs, drawings, an exploded view with a parts list, the damping pattern and the schematic. The crossover screws into the cabinet with eight 4 x 16 mm wood screws. The binding posts go on a stainless terminal panel. The drivers fix with hex socket screws into threaded inserts (M5 for the woofer, M4 for the rest). SB's damping pattern gives nine pieces of 20 mm Dacron per speaker.
Who it suits
- Good fit: someone who likes the Gema's look but has a smaller room, and is happy doing both the woodwork and the crossover. The 8-ohm rating is an easy load for most amps.
- Think about: 84 dB sensitivity with SB recommending 100 to 200 W, so it wants a reasonably strong amp. It's a full build from SB's drawings and schematic, so budget the time. At 21.8 kg and 610 mm tall, plus a stand, it's still a big speaker.
SB's documents
- Rima user manual (specs, drawing, exploded view and parts list, damping pattern, crossover schematic)
- Rima cabinet drawing
- SB's Rima page