SB Acoustics “Satori” MW16P-4

Overview:

 

The MW16P-4 is a 4Ω mid-woofer from the SB Acoustics Satori series. Satori in Japanese is a Zen Buddhist term for enlightenment. The word literally means “awakening”, “comprehension” and understanding”.

The driver has a very nice looks and build quality. The small but yet powerful neodymium magnet together with the shape of the chassis contributes to an optimal airflow behavior.

It has a for its size great excursion capabilities with a linear coil travel of +/- 6mm.

Key features:

  • Proprietary cone material with EGYPTIAN PAPYRUSTM fibres made in-house
  • Soft low damping rubber surround for optimum transient response
  • Advanced BIMAX spider for improved linearity
  • Powerful optimized low distortion neodymium motor system
  • Non-conducting fibre glass voice coil former for minimum damping
  • Extended copper sleeve on pole piece for low inductance and reduced distortion
  • Vented aerodynamic cast aluminum chassis for optimum strength and low compression
  • CCAW voice coil for reduced moving mass
  • 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: SBAcoustics Satori MW16P-4

 

T/S Parameters:

 

Nice consistency between the two driver unit samples. About 25% higher Mms compared to the official spec sheet.

Impedance:

 

(click on picture to zoom)

Left: Free-air impedance sample 1 vs. sample 2.
Right: Close-up of free-air impedance sample 1 vs. sample 2.

The MW16P-4 has a very sharp and narrow impedance peak at the resonance frequency of the driver unit, which indicates a mid-woofer with low mechanical losses.

Some wrinkles in the impedance plot are visible at about 1.2-1.3, 4 and 6kHz. The 1.2-1.3kHz wrinkle is the mid-woofers cone edge resonance due to the low mechanical damping of the surround. The other wrinkles might be some resonance issues and are shown as dips at the same frequencies in the frequency response.

At 4-6kHz there is a slight difference in the impedance plot between the two driver unit samples.

Frequency:

 

Frequency measurement conditions:

The mid-woofer is measured mounted on a baffle in an 14 liter closed enclosure with the following conditions:

Baffle size (WxH): 24,8×35,8cm with 18mm round-over on the baffle edges (r=18).
Driver position: Mounted on center-line with driver unit center 19,5cm from the top of the baffle.
Mic position: 1m distance, on mid-woofer-axis.
Smoothing: 1/24 octave smoothing applied.

(click on picture to zoom)

Left: Frequency response on-axis (Blue=sample1, Red=sample2).
Right: Frequency response 15deg off-axis (Blue=sample1, Red=sample2).

The two mid-woofer samples measures virtually the same, which indicates good consistency in the manufacturing process.

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

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

Due to the mid-woofers very low inductance and flat impedance response, the on-axis frequency response has an extremely linear and extended response up to 15kHz.

The broad hump between 0.5-1.4kHz is partly due to the shape of the baffle and the baffle step. When the baffle step is taken care of in the cross-over design with the “proper baffle step compensation”, we have a very linear frequency response up to 3kHz which is about the highest suitable cross-over frequency for this mid-woofer.

Distortion:

 

Measurement setup:

  • Mid-woofer near-field measurement at 15cm
  • Frequency Range Mid-woofer: 200-10000Hz
  • Baffle size WxH: 24,8×35,8cm

The distortion measurements are done in near-field and the amplifier output level was adjusted for each driver so that the fundamental is 85dB, 90dB and 95dB at 1m. This setting simulates normal to medium-high and high listening levels.

85dB @ 1m (click on picture to zoom)

Left = Sample 1

Right = Sample 2

90dB @ 1m (click on picture to zoom)

Left = Sample 1

Right = Sample 2

95dB @ 1m (click on picture to zoom)

Left = Sample 1

Right = Sample 2

Overall this is a very low distorting mid-woofer. We have the expected harmless elevated second-order harmonics around 1.2KHz due to the cone edge resonance, but in this case we also have some elevated third-order harmonics at the same frequency.

Due to the overall very low odd-order distortion the odd-order spike might look worse than it is. The driver unit sample 1 has a more severe odd-order peak of 0.37% @ 95dB/1m compared to sample 2 which has 0.26% at the same frequency and level. Still this is distortion numbers that most good drivers will have throughout the frequency range at this listening level and the overall distortion performance of this mid-woofer is excellent.