12 inch Precision Response Carbon Fibre

Jaycar Part no: 2279 - Cost $219.00aus (5th May 2005)

This driver can be had for $177.20 + postage at New-Media.com (25th Jan 2008)

Estimated values are highlighted in red

Single coil driven 2 series coils 2 parallel coils
Znom Nominal Impedance 4 ohms 8 ohms 2 ohms
Pmax Power Handling 150 watts 300 watts 300 watts
SPL Sensitivity dB/watt@1m 85.152 88.152dB/watt@1m 88.152
Re Voice coil resistance 3.4 ohms 6.8 ohms 1.7 ohms
Fs Resonant frequency 28.77 hz 28.77 hz 28.77 hz
Qms Mechanical Q 3.238 3.238 3.238
Qes Electrical Q 0.892 0.446 0.446
Qts Total Q 0.699 0.392 0.392
Vas Equivalent volume 79.454 litre 79.454 litre 79.454 litre
Xmax Maximum excursion 9mm 9mm 9mm
Sd Cone Area 514.720 sq cm 514.720 sq cm 514.720 sq cm
EBP Efficiency Bandwidth Product 32.3 - sealed 64.5 - all rounder 64.5 - all rounder

 

Here are the driver files for WinISD Pro ver 0.50a7

Here is my parameter file for this driver ( single coil driven )

Here is my parameter file for this driver ( two series coils driven )

Here is my parameter file for this driver ( single coil driven, second coil shorted)

The Xmax figure is not stated in the catalog, but Jaycar provide a link on their website, where the details for this driver eventually lead to a screenshot of an analysis using "BassBox" software. On that page Xmax is shown as 9.0mm, which is the value I used above. The screen shows designs using the 1.7ohm parallel arrangement, which is not suitable for use with the HT plate amps. It also shows Sd = 708 sq cm as opposed to 514 in the catalog

Suggested designs

There are more designs here than usual, for several reasons.

  • Firstly, there are three ways to wire this driver - single coil of 4 ohms, utilsing the 240w amp, or both coils in series, giving 8ohms, which requires the larger 350w amp, or one coil driven with the second coil shorted using the 240w amp.

  • Secondly, I wanted to show three extra designs which exceeds my target box size of 130 litres, but give better responses for Home Theatre.

  • Lastly, since this is a possible replacement for the 10inch titanium, (which I consider to have been their best HT driver), I wanted to explore all the options.

  • Since the graphs are already crowded, I have omited any sealed designs - they are poor performers in the 25hz area anyway.

Jaycar shows no designs in their catalog, so these are all mine

 

Ported - single coil 550 litre - 100w-4ohm - 240w amp 22hz Four 86mm ports @ 198mm
Ported - single coil 130 litre - 150w-4ohm - 240w amp 26hz Two 102mm ports @ 482mm
Ported - series coils 230 litre - 240w-8ohm - 350w amp 24hz Two 102mm ports @ 294mm
Ported - series coils 130litre - 240w-8ohm - 350w amp 26hz Two 86mm ports @ 333mm
Ported - single driven second coil shorted 260litre - 150w-4ohm - 240w amp 25hz Two 102mm ports @ 226mm

 

SPL

Unless you go to a very large box, you cant get a flat response, even with a ported design.

The single coil arrangement gives better output than the series connection.

The orange curve is the shorted coil option and still requires 260 litres

 

Cone excursion

Tthe brown graph which indicates that 130l/26hz design needs an infrasonic filter

The 550 litre ported design had to have power reduced because of excursion limits

 

Port air velocity

Port flares would be required - see the note at the bottom of this page

 

 

Unlike the 10inch version, this driver won't produce a flat response in a 130litre box. Going up to 260 litres will give 107dB flat using the 350w amp.

Here are the project files for WinISD Pro ver 0.50a7

550 litre ported 22hz tune (single coil)

130 litre 26hz tune (single coil)

230 litre 24hz tune (series coils)

130 litre 26hz tune (series coils)

260 litre 25hz tune (one coil driven, one coil shorted)

 

Port Flares - calculated with Flare-it

Ported - single coil design. Four 86mm ports, peak velocity 11.5m/sec @ 22hz

Minimum flare radius required 25mm.

Use 25mm heat molded flares

 

Ported - single coil design. Two 102mm ports, peak velocity 10m/sec @ 25hz

Minimum flare radius required 13mm.

Use 13mm routed flares. Alternatively, you could move to heat molded flares in 20mm or 25mm radius.

 

Ported - series coils design. Two 102mm ports, peak velocity 10m/sec @ 25hz

Minimum flare radius required 13mm.

Use 13mm routed flares. Alternatively, you could move to heat molded flares in 20mm or 25mm radius.

 

Ported - series coils design. Two 86mm ports, peak velocity 11m/sec @ 25hz

Minimum flare radius required 25mm.

Use 25mm heat molded flares

 

Ported - single driven second coil shorted design. Two 102mm ports, peak velocity 13m/sec @ 25hz

Minimum flare radius required 22mm.

Use 25mm heat molded flares

 

In all designs, the intakes should be flange mounted with a 13mm routed flare or you could fit a donut ring . If you are using a heat molded flare, you could do a one-piece design with a 20mm flare on the inlet

Depending on the flaring options, you'll need to adjust the physical length so that the effective length is as shown above. The port flares page has a section on calculating effective length as well as some information on availability of commercial flares.

 
 

Last update to this page 10th December 2006

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