BMS
BMS 12S305
BMS 12S305: 12″ woofer with 3″ copper voice coil and ±11 mm Xmax, which the manufacturer recommends for compact subwoofers with 30 to 40 L bass reflex.
Current · Last checked: 2026-11-13
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General data
Link to section “General data”- Type
- Woofer
- Nominal size
- 12″
- Nominal impedance
- 8 Ω Manufacturer
- Minimum impedance
- not available
- Sensitivity
- 95 dB 1 W / 1 m Manufacturer
- Frequency range
- 35 Hz – 2,500 Hz Manufacturer
- Voice coil Ø
- 77 mm Manufacturer
- Winding height
- 32 mm Manufacturer
- Gap depth
- 10 mm Manufacturer
- Flux density
- not available
- Magnet
- not available
- Weight
- 8 kg Manufacturer
- Baffle cut-out Ø
- 284 mm Manufacturer
- Overall diameter
- 318 mm Manufacturer
- Mounting depth
- 153 mm Manufacturer
- Displacement
- not available
- Recommended enclosure volume
- 30 – 40 L Manufacturer
BMS states only the AES power handling, no programme power. BMS measures the frequency response with 100 W (28.3 V) at 1 m in a sealed 50-litre enclosure in an anechoic chamber. BMS gives the inductance at 10 kHz as 0.41 mH.
As a bass reflex enclosure BMS recommends 30 L with 50 Hz tuning (port tube 100 mm diameter, 226 mm long) or 40 L with 45 Hz (port tube 100 mm, 204 mm long). Copper voice coil, cast aluminium basket; the product page does not state the magnet material.
What can this driver do?
Link to section “What can this driver do?”Simulation from the datasheet values above. The suggestions are calculated, not stated by the manufacturer.
The EBP is above 100 – by the rule of thumb, this points to a vented enclosure (bass reflex). This is based on an EBP of 125.9.
- Net volume
- 39 L
- Tuning frequency
- 52.5 Hz
- F3 (−3 dB)
- 50.7 Hz
- F6 (−6 dB)
- 45.7 Hz
- F10 (−10 dB)
- 40.4 Hz
- Sensitivity (2.83 V / 1 m)
- 94.8 dB
- Max. SPL at 50.7 Hz
- 120.8 dB
- Max. SPL at 101 Hz
- 123.6 dB
- Xmax limits below
- 44.1 Hz
- Ports
- 1 × 160 mm
- Port area for 17 m/s
- 318 cm²
- Max. port velocity
- 26.9 m/s
- Port length
- 44.2 cm
- at 800 W
- Maximum SPL (limited by Xmax)
- Power into 8 Ω (nominal impedance of the wiring).
- Flattest alignment: lowest F3 without the response rising more than 0.25 dB above the passband level or dropping more than 0.5 dB at 2 × F3.
- The 17 m/s limit (about 5 % of the speed of sound) is a common rule of thumb against port noise, not a standard. Rounded port ends allow higher values.
- Lumped-element Thiele/Small model, Half space, 1 m, chamber losses QL 7, Le as a plain inductance, no room influence. At high levels (heating, non-linear Bl and Cms) real results are lower.
Thiele-Small parameters
Link to section “Thiele-Small parameters”Small-signal parameters as stated by the manufacturer. They change with temperature and level.
Plausibility check
Link to section “Plausibility check”We recalculate dependent values from the datasheet. We flag deviations above 3 %.
| Check | Formula | Datasheet | Calculated | Result |
|---|---|---|---|---|
| Qts from Qes and Qms | Qts = Qes · Qms / (Qes + Qms) | 0.265 | 0.265 | consistent |
| Xmax, geometric | Xmax = (winding height − gap depth) / 2 | 11 | 11 | consistent |
Power handling
Link to section “Power handling”- AES800 W
Build plans with this driver
Link to section “Build plans with this driver”Sources
Link to section “Sources”-
Tier A · primary source
BMS 12S305 – Product page with Thiele-Small parameters and mounting dimensions
BMS Speakers GmbH · accessed on 13 November 2026
Product page “12″ Ultra low Distortion Driver – 12S305” with the tabs Specification, Thiele-Small and Mounting & Drawing. The driver is not in the “Discontinued” category.
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Tier A · primary source
PS-Sub112 – Datenblatt und Bauplan (PDF)
PlanSound GbR · November 2024 (Date from file metadata) · accessed on 13 September 2026
Six pages: technical data, raw measurement, measurements with tops, DSP preset, photo, build plan with parts lists for 15 and 16 mm. Created on 12 November 2024 according to the file metadata.