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Jaycar 12 inch Carbon Fibre Cone subwoofer

Jaycar Part no: CS-2246 - Cost $159.00aus (5th May 2005)

Z - Nominal Impedance4 ohm
Pe - Power Handling200 W
SPL - Sensitivity93 dB/watt@1m
Re - Voice coil resistance3.5 ohm
Fs - Resonant frequency21.6 hz
Qms - Mechanical Q12.29
Qes - Electrical Q0.294
Qts - Total Q0.288
Vas - Equivalent volume220 litres
Xmax - Maximum excursion6 mm
Sd - Cone Area494 sq cm
EBP - Efficiency Bandwidth Product75 - All rounder

Here is my parameter file for this driver for WinISD Pro ver 0.50a7

This driver is limited by an Xmax of only 6mm. This figure is not in the catalog and was found via the Jaycar forum. You won't be able to use the full 200w rating, but the good sensitivity makes up for that.

There are two exursion peaks in a Bass Reflex design. In the case of these designs, there is a peak around 40hz and another below the tuning frequency.

The first peak can be addressed either by using a smaller box, or by decreasing power. The smaller box costs efficiency and hurts in the 25-30hz range which we want to maximise. A smaller box also requires longer ports. The compromise I suggest is to leave the box at 95 litres and reduce power till excursion becomes acceptable. The Jaycar designs require 180w (240w amp) for the 60 litre design and 120w (240w amp) for the 95 litre design. My 95 litre design uses the 80w amp

The second excursion peak (below tuning frequency) can be addressed by using a high pass filter which both the Jaycar designs require. An alternative approach which I use is to go for a lower tune, thus moving the problem to below about 18hz, where there is virtuallly no full strength content on a DVD.

Designs

Box size Tuning frequency Port details
Jaycar design 95 litres 30hz One 110mm port 252mm long
Jaycar design 60 litres 30hz One 110mm port 446mm long
My design 95 litres 24hz Two 76mm flared ports 441mm long

Project files for WinISD Pro ver 0.50a7
Jaycar 95 litre 30hz design incl 16hz filter
Jaycar 60 litre 30hz design incl 17hz filter
My 95 litre 24hz design

SPL

SPL graph
Jaycar 95l - 120w
Jaycar 60l - 180w
My 95l - 80w
 

Cone excursion

Excursion graph
Jaycar 95l with 16hz filter
Jaycar 60l with 17hz filte
Dotted lines show Jaycar designs without high pass filter
 

Port air velocity

Velocity graph
Jaycar 95l design is under-ported
 

All three designs give similar performance at 25hz. My design is the most economical, using the cheaper 80w amp and not requiring the high pass filter. Now that the "10inch titanium finish" driver is discontinued, I would suggest this as a replacement for the Snorky design. This gives you 106dB

If you want more "slam", use the 240w amp and build the high pass filter. The Jaycar 95 litre box is slightly better than the 60 litre design, but not by enough to justify the increase in size. This gives you 110dB

If you want even more output, you could use a dual driver box and run the drivers in series. This would present an 8ohm load and run from a single 350w amplifier. One 190litre box (or a pair of 95's) needs 240w which is exactly what the 350w amp delivers into 8ohms. You will get 117dB peak output

Although smaller than recommended here, one builder put a pair of these drivers in a 75 litre box tuned to 32hz. He used standard Jaycar ports, their 350w amp and didn't go with a filter. He's very happy with it. You can see a few pics in the inspirations from the net section

 

Port Flares

Calculated with Flare-it
I would change my recommended porting to a single 103mm port 380mm long fitted with a 25mm radius heat molded flare on the port exit. An alternate solution would be to use a pair of 86mm ports 573mm long fitted with 19mm flares. If you have a full size router, you can use a 19mm rollover bit for routed flares. Otherwise you would need to move to heat molded flares in 20mm or 25mm radius.

In each case, the port intakes should fitted with 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
See the Porting section for more detail on the design, construction and purchase of flared ports.

 

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