The CA12RCY is a 4.5″ mid-woofer from the Seas Prestige series. It uses a handcoated paper cone with coated fabric dust cap and a natural rubber surround,which reduce resonances and distortion.

The large magnet system and a symmetrical driving force accomplished through a special coil winding technique for the voice coil gives an excellent linearity.

Very large magnet system provides a reasonable efficiency and a low Q. Extremely stiff and stable injection moulded metal basket keeps the critical components in perfect alignment.

Large windows in the basket both above and below the spider reduce sound reflexion, air-fl ow noise and cavity resonance to a minimum.

SEAS spec sheet: CA12RCY

T/S Parameters:


T-S parameters CA12RCY

Slightly higher voice-coil resistance and sensitivity than the official specification.




Minor wrinkles in the impedance plot between 0.8-1,5kHz.



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 hump between 500 and 1.1kHz is due to the effects of the test enclosure’s baffle step. There is no sign of any cone edge resonance and the frequency response is very smooth up to 4.5kHz with a gentle roll-off from 1.5kHz. A small cone break-up is visible around 6.5kHz.


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 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.

CA12RCY-3L--15cm 85dbCA12RCY-4R--15cm 85db

(click on picture to zoom)

85dB @ 1m

Left = Sample #1

Right = Sample #2

CA12RCY-3L--15cm 90dbCA12RCY-4R--15cm 90db

(click on picture to zoom)

90dB @ 1m

Left = Sample #1

Right = Sample #2

CA12RCY-3L--15cm 95dbCA12RCY-4R--15cm 95db

(click on picture to zoom)

95dB @ 1m

Left = Sample #1

Right = Sample #2

Compared to the SEAS Excel line of 4.5” mid-woofers and by today’s standards, the CA12RCY mid-woofer only has an average third-order distortion performance in the upper mid-range. There is an increase of third-order distortion around 2.2kHz, which corresponds to the minor cone break-up at 6.5kHz.

Higher orders of distortion are low, but the relatively harmless second-order distortion profile is high throughout the frequency range at levels above 90dB.