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350Z » Audio » Woofers

Develop the Plan
The 350Z doesn't have a lot of extra space. Wanting to build woofer boxes I decided to do this in front of the rear strut bar. The first step then is to choose the speaker and what the enclosure will be made of.

P28S8 - 8" Punch Stage-2 (8 ohm) subwoofer
I guess the first questions will be - why did I choose this speaker - The brand and the size? I don't get too bent around arguing why one product is better then another. For one reason, I don't consider myself an expert on these things. I try to make the best decision I can with the information I have and then consider that 'well enough'. So, with that said: Why use a pair of 8" woofers? Some people have used one or a pair of 10", 12" or larger woofers. It seems to me that, personally, giving up the entire trunk area just wasn't something that I wanted to do. I noticed that the area in front of the strut on either side of the opening isn't hardly ever used. The question then became - could I use that area. A quick and dirty measurement convinced me that I could put in a pair of 8" woofers.

Forward strut pocket	Dimensions
This space isn't used much at all. If I could put the woofer back here you are really not losing any space at all. The other thought was that if I could match the texture and color I could make it look like it was factory built. Stealth in plain view - as it were.	The pocket is hard to get exact measurement of the cu.ft. but we should easily at least .3 ft³ You have the remaining width of the car to add any remaining needed space. Holding the speaker in the pocket quickly confirmed that we have enough space to physically mount it here.

Why the Rockford Fosgate Woofers? From Rockford-Fosgate:

The RF Punch SVC Woofers are a full line of low frequency drivers sized from 8" to 15" and are available in 4 or 8 ohm impedance. The RF Punch SVC woofers were designed for use primarily in small, sealed or ported enclosures. By utilizing the latest materials and construction techniques, we are able to offer a speaker with high output at low frequencies while requiring a minimum of operating space.

8" Punch Stage 2, SVC subwoofer with parabolic injection molded Polypropylene cone, 2" aluminum voice coil former, insulated 16 AWG tinsel leads, linear spider, 2" excursion, 30 oz motor structure, Cold rolled vented steel basket with removable motor cover, 8 AWG compression terminals, optimized for small sealed enclosures, 200 watts RMS/400 watts peak. Mounting depth 4.0".

Why 8-ohm speakers? The choice of these speakers was in paralell with the choice of amplifiers. I am using a Profile CA600M amplifier to power the subs. The CA600M RMS Power @ 4 Ohms is 1x300W (bridged). I chose 8 ohm speakers so hooked in parallel so the amp shows a 4 ohm load.

What material for the enclosure and how thick? ¾ MDF is the recommended material. Because of the crazy angles and curves, I'm going to go with fiberglass. That then begs the question "How Thick Should Your Fiberglass Enclosure Be?". Clicking that link will take you to a page where that very question is pontificated on:

"Bottom line: Fiberglass enclosure thickness is based on many factors and no one can tell you how many layers or how thick your subwoofer box should be because all enclosures are unique. ..... My rule of thumb for thickening subwoofer enclosures is a real rule of thumb. After the enclosure has cured I test it by pushing on various areas of the enclosure with my thumb. If I find a spot that flexes I know it needs more thickening."

Good enough for me. I will try to get it at least 3/8" thick and then use the "Rule of Thumb" as needed.


	Page 2: Caculate the Volume

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