ScanSpeak 18W4531-G01



The 18W/4531-G01 is a 4Ω mid-woofer from the ScanSpeak Revelator series.

It uses a sliced wood fibre cone technology. The slices are filled with damping glue, which dramatically reduces breakup modes in the diaphragm. In combination with Scan-Speaks low-loss linear suspension and the patented Symmetrical Drive (SD-1) it represented a break through in midrange clarity and overall smooth frequency response characteristics.

The 38mm voice-coil has a glass fiber voice-coil former.

Key features:

  • —Patented Symmetrical Drive Motor Design
  • Wood fibre cone
  • —Low-Loss linear suspension
  • Die cast Alu Chassis vented below spider
  • Sliced Cone (Controls Cone Breakups)
  • Low Damping SBR Rubber Surround
  • Large Ferrite Magnet System


ScanSpeak Spec sheet: 18W/4531G-01

T/S Parameters:


18W4531G01 - TS parameters

Higher sensitivity, resonance frequency and Qts compared to the official specification. This is unfortunately common with many Scanspeak mid-woofers.

Note! The cone area differs from the official specification.



18W4531G01 - Imp

Minor differences between the two tested driver unit samples. A small wrinkle in the impedance plot can be seen around 800Hz.



Frequency measurement conditions:

The mid-woofer is measured mounted on a baffle in an 19 liter closed enclosure with the following conditions:

Baffle size (WxH): 24×35cm with 18mm round-over on the baffle edges (r=18).
Driver position: Mounted on center-line with driver unit center 23,7cm from the top of the baffle.
Mic position: 1m distance, on mid-woofer-axis.
Smoothing: 1/24 octave smoothing applied.


18W4531-G01 Freq 0deg 1L vs 2R tw-axis18W4531-G01 Freq 15deg 1L vs 2R

(click on picture to zoom)

Left: Frequency response on-axis (Blue=sample#1 Red=sample#2).
Right: Frequency response 15deg off-axis (Blue=sample#1, Red=sample#2).

The two mid-woofer samples measures virtually the same.

18W4531-G01 Freq 0-15-22.5deg 1L

0deg = Blue
15deg = Red
22.5deg = Green

18W4531-G01 Freq 30-45-60deg 1L

30deg = Blue
45deg = Red
60deg = Green

Very smooth frequency response. The mid-woofer starts to roll-off at 2kHz and a good start for a x-over cross-over point would be somewhere around 1.8-2.2kHz.



Measurement setup:

  • Mid-woofer near-field measurement at 15cm
  • Frequency Range Mid-woofer: 200-10000Hz
  • Baffle size WxH: 24×35cm

The distortion measurements are done in near-field and the amplifier output level was adjusted for each driver so that the fundamental is 90dB and 95dB at 1m. This setting simulates medium-high and high listening levels.

18W4531G-01_58032-5-1L--15cm 90db18W4531G-01_58032-15-2R--15cm 90db

(click on picture to zoom)

90dB @ 1m

Left = Sample #1

Right = Sample #2

18W4531G-01_58032-5-1L--15cm 95db18W4531G-01_58032-15-2R--15cm 95db

(click on picture to zoom)

95dB @ 1m

Left = Sample #1

Right = Sample #2

Elevated second-order harmonics between 0.4-1kHz, but the odd-order distortion profile is very low throughout the frequency range.