SB Acoustics “Satori” WO24P-4



The SB Acoustics Satori WO2P-4 is an 4Ω 9.5″ woofer from SB Acoustics. The woofer has a 49.5mm voice-coil with a 17mm (p-p) linear coil travel. It’s fitted with dual shorting rings in motor system for reduced distortion.

Key features:

  • Hard paper cone for improved piston operation (made in-house)
  • Large optimized motor system with under-cut pole piece and
  • dual shorting rings
  • Vented aerodynamic cast aluminium chassis for optimum
  • strength and low compression
  • Soft low damping rubber surround for optimum transient response
  • Linear symmetric suspension design for improved dynamic
  • performance
  • Non-conducting fibre glass voice coil former for minimum damping
  • Long life silver lead wires attached 180° apart for improved stability
  • Vented pole piece for reduced compression
  • High piston to chassis diameter ratio
  • Gasket and bolt hole protrusions for reduced coupling to speaker cabinet


SB Acoustics Spec sheet: 9in Satori WO24P-4

T/S Parameters:





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Blue: Mid-woofer sample #1

Green: Mid-woofer sample #2

A small resonance issue around 1.1kHz



Frequency measurement conditions:

The mid-woofer is measured mounted on a baffle in an 27 liter closed enclosure with the following conditions:

Baffle size (WxH): 30×40cm, no flush mount.
Driver position: Mounted on center-line with driver unit center 24cm from the top of the baffle.
Mic position: 1m distance, on woofer-axis. Nearfield at 10cm from dust-cap.
Smoothing: 1/24 octave smoothing applied.


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Frequency response on-axis near-field 10cm from dust-cap (Blue=sample#1, Red=sample#2).

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Frequency response 1m, on-axis (Blue=sample#1 Red=sample#2).

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

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



Measurement setup:

  • Woofer near-field measurement at 20cm
  • Frequency range woofer: 100-10000Hz
  • Baffle size WxH: 30×40cm

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.


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90dB @ 1m

Left = Sample #1

Right = Sample #2


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95dB @ 1m

Left = Sample #1

Right = Sample #2

The Satori WO24P-4 woofer is a low distortion driver. The resonance issue shown in the impedance plot around 1.1kHz is shown here as an elevated odd order distortion.  The woofer’s odd-order distortion is low below 0.8kHz and it has an increasing odd-order distortion above 0.8kHz.