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Peerless 830847 XXLS12

308 mm XXLS home subwoofer with 8 + 8 Ohm voice coil. For small enclosures of around 58 litres.

Peerless 830847 at EssentialAudio - $309 AUD including GST (16th February 2009)

Peerless 830847 at Speakerbits - $336.36 AUD excluding GST (16th February 2009)

Double Voice Coils 8ohm + 8ohm in parallel
Z - Nominal Impedance 4 ohm
Pe - Power Handling350W (175 continuous)
SPL - Sensitivity86.9 dB/watt@1m
Re - Voice coil resistance2.5 ohm
Fs - Resonant frequency21.8 hz
Qms - Mechanical Q10.24
Qes - Electrical Q0.37
Qts - Total Q0.36
Vas - Equivalent volume 144.2 litre
Xmax - Maximum excursion12.5 mm
Sd - Cone Area466 sq cm
EBP - Efficiency Bandwidth Product57 - All rounder

Driver parameter file for this driver for WinISD Pro ver 0.50a7

Designs

Box size Tuning frequency Port details
My design 70litre box 26hz tuning Two 102mm ports 947mm long
My design 54 litres sealed
Project files for WinISD Pro ver 0.50a7

My 70 litre 26hz design incl 14hz filter
My 54 litre sealed design

SPL

SPL graph
Ported with 350W amp incl boost
Not bad as you would expect of a 12 inch driver with 350w applied. Excursion limits prevented an EBS tune which would have been flatter and yielded more @ 25hz
Since the EBP value suggests a sealed design, I have modelled it in red. Excursion limits dictate using the 240W amp incl boost

Cone excursion

Excursion graph
Below 20hz, excursion becomes excessive as shown in blue. This requires a 14hz high-pass filter to tame as shown in green.
Sealed design shown in red

Port air velocity

Velocity graph
Two 4 inch ports are needed to get velocity to around 10 m/sec. Pipe resonance is around 180hz.

Most people would probably go for the sealed design which doesn't require the filter. The ported design gives more, but requires a larger amp, a high pass filter and the need to use long ports. Peerless designs use passive radiators to overcome the port problem.

Port Flares

Calculated with Flare-it
I would recommend a 13mm routed flare.
The intake could be flange mounted with a 13mm routed flare or you could fit a donut ring.
Depending on the flaring options, you'll need to adjust the physical length so that the effective length is as shown in the designs.
The port flares page has a section on calculating effective length as well as some information on availability of commercial flares.

 

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