PASpeaker-Base
18″ Bandpass

Speakerplans C Sub

18″ bandpass (“Coupled Cavity”) by Rog Mogale – 35 to 90 Hz and 103 dB sensitivity according to the drawing, five suitable drivers.

Partially verified Last checked: 14 September 2026 What does this mean?

Primary source checked; some values are missing from the source or still open.

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Specifications

Link to section “Specifications”

Every value with its provenance. If a value is missing from the source, it reads “not available”.

Drivers
1 × Precision Devices PD 1850 Designer
Enclosure type
Bandpass
Low-frequency extension
not available
Sensitivity
103 dB 1 W/1 m (Grafik “Input 1/w, Distance 1m”) Designer
Max. SPL
not available
Power handling
not available
Impedance
not available
Dimensions (H × W × D)
1,000 × 500 × 626 mm from drawing, Front and side view Designer
Volume
not available
Tuning frequency
not available
Weight
not available
Recommended high-pass
not available

External dimensions from the front and side views (“All measurements in mm”).

Description

Link to section “Description”

In brief

A bandpass for an 18-inch driver with a crossover at 80 Hz. The designer gives the frequency range, sensitivity and five suitable drivers.

The C Sub is a bandpass for an 18-inch driver by Rog Mogale. The drawing calls it “Coupled Cavity Enclosure”: the driver sits between two chambers, and the sound exits through a slot port.

What the drawing states

Link to section “What the drawing states”
  • Bass from 35 to 90 Hz, crossover at 80 Hz
  • 103 dB sensitivity, frequency response graph at 1 W / 1 m
  • “Short throw design” – designed for drivers with little excursion
  • removable rear panel for installing the driver

The designer names five suitable drivers in order of preference. A driver with similar key data is only an alternative once a simulation with the chamber dimensions fits.

Drivers

Link to section “Drivers”

Enclosure

Link to section “Enclosure”
Enclosure type
Bandpass · How does it work?
Shape
Rectangular box
Ports
  • 1 × slot port 224 × 125 mm length 314 mmSlot port in the lower chamber (“Port 314 deep”)
Material
not stated

Build plan

Link to section “Build plan”

We link to the original plan and do not host other people’s drawings.

  • C Sub – Plan-Seite mit Zeichnungen auf Speakerplans.com (englisch)

    Official source · accessed on 13 September 2026

    Free to download

    Open original document

Plan access: Free

Curves in the original document

The drawing includes a frequency response graph (“Input 1/w, Distance 1m”). It does not say whether it is measured or simulated. We do not read any values from it.

Crossover & controller

Link to section “Crossover & controller”
Crossover
80 Hz · Crossover point according to the drawing (“Xover point 80Hz”). Filter type and slope not stated.
Recommended high-pass
not stated

Pros and cons

Link to section “Pros and cons”

Pros

  • Sensitivity and crossover frequency given
  • Five suitable drivers in ranked order

Cons

  • Frequency range given without reference level
  • No information on chamber volumes and tuning

Sources

Link to section “Sources”
  1. Tier A · primary source

    Speakerplans.com – C Sub – Coupled Cavity Enclosure

    Rog Mogale · Speakerplans.com · 2000 · accessed on 13 September 2026

    According to the drawing, up to four enclosures may be built; anyone who wants to make money with them should ask the designer for a licence.

  2. Tier B · secondary source

    Speakerplans.com – Speaker plans (overview)

    Rog Mogale · Speakerplans.com · accessed on 13 September 2026

    Overview with Horn Plans, Sub Plans and Mid Top Plans. The plans are embedded as images (drawings) on the individual pages.

Usage rights of the plan: Free to download. Added on 14 September 2026, last updated on 14 September 2026.

Further reading

Link to section “Further reading”