SEAS E0044 W12CY003



W12CY003The W12CY003 is a 4.5″ mid-woofer from the Seas Excel series. It uses a paper cone with a Nextel coating, which ensures smooth frequency response and low distortion.

Heavy copper rings are mounted above and below the T-shaped pole piece and reduces the non-linear and modulation distortion and increase the overload margin.

A large magnet system provides good sensitivity and transient response.

A chrome plated brass phase plug reduces compression due to temperature variations in the voice coil, increases long term power handling capacity and eliminates resonances in the cavity inside the voice coil former.

An extremely stiff and stable injection moulded nextel coated metal basket keeps the critical components in perfect alignment. Large windows in the basket both above and below the spider reduce sound reflexion, air-flow noise and cavity resonance to a minimum.

SEAS spec sheet: W12CY003

T/S Parameters:


T-S parameters W12CY003

Slightly higher sensitivity and a considerably higher resonance frequency than the official specification.




Some sort of resonance issue can be seen around 950Hz.



Frequency measurement conditions:

The mid-woofer is measured mounted in a 8 liter Dayton Audio enclosure (PartsExpress part #302-701) baffle with the following conditions:

Baffle size (WxH): 19×30,5cm with 12mm round-over on the baffle edges (r=12).
Driver position: Mounted on center-line with driver unit center 20,2cm 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=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. The broad hump between 500 and 1.1kHz is due to the effects of the test enclosure’s baffle step. There is a dip in the frequency response at 1.1KHz, probably due to a cone edge resonance.


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


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

The mid-woofer starts to roll-off at 3.5kHz and has a very extended and relatively smooth  frequency response.



Measurement setup:

  • Mid-woofer near-field measurement at 15cm
  • Frequency Range Mid-woofer: 200-10000Hz
  • Baffle size WxH: 19×30,5cm


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 medium, medium-high and high listening levels.

W12CY003-1L--15cm 85dbW12CY003-2R--15cm 85db

(click on picture to zoom)

85dB @ 1m

Left = Sample #1

Right = Sample #2

W12CY003-1L--15cm 90dbW12CY003-2R--15cm 90db

(click on picture to zoom)

90dB @ 1m

Left = Sample #1

Right = Sample #2

W12CY003-1L--15cm 95dbW12CY003-2R--15cm 95db

(click on picture to zoom)

95dB @ 1m

Left = Sample #1

Right = Sample #2

Overall this is a low distorting mid-woofer. We have an elevated second-order harmonics between 0-4-1.2Hz, which follows the frequency response of the baffle step.

There is a narrow banded increase of third-order distortion at higher levels (95dB) around 950Hz that corresponds to the wrinkle in the impedance plot at the same frequency.

Otherwise the odd-order distortion profile is low throughout the frequency range up to about 4kHz.