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View Full Version : Stealth+ Subwoofer Project for the Avant :)



Jeff
06-22-2009, 12:07 AM
Since I haven't posted much regarding stereos, I figured that I'd share my little sub project in my Avant. [:D]

(I've been an audiophile for over 20 years, but never touched the system on the Audi's til recently...haha)

I opted to go with a 6.5" (7") sub over a larger 8, 10, or even 12 inch in the CD Changer compartment for the reason of preserving that space for my amp and other misc. equipment. I'm typically not a fan of mounting amps on panels and exposed in the cabin/trunk. A 6.5" was the only logical solution (and lighter/smaller). Tuned to 38Hz on the box, the sub is able to hit some extreme frequencies.

http://www.audigeeks.com/images/jeff/B5/avant/sub8.jpg

http://www.audigeeks.com/images/jeff/B5/avant/sub9.jpg

Tuning:

A PERFECT response curve was achieved with the parameters I used. The BLUE curve (51Hz) is the typical design used in most sub applications (recommended by manufactures)...it allows a more "boomy" and punchy bass. I chose to tune the box to the subs FS (resonant frequency), which will allow the sub to compensate for it's smaller size, and extend the lower frequencies (the RED curve)

http://www.audigeeks.com/images/jeff/B5/avant/sub10.jpg

More pics on the build process here:

http://www.audigeeks.com/forums/index.php?topic=3317

biketsai
06-22-2009, 12:13 AM
I like it, pretty stealth like! I wouldnt mind having a small sub that hits either!

Jeff
06-22-2009, 12:16 AM
I like it, pretty stealth like! I wouldnt mind having a small sub that hits either!

The small sub is hitting as hard as the 10" i had in a 0.75 cu ft sealed box. Tuning is key...like turbos and A/F. [:D]

zrowcool
06-22-2009, 07:11 AM
is the box completely fiberglass? i'm pretty good at tuning a box when they are mdf but how would you tune it in fiberglass? in mdf i can just calculate the inside volume and then just calculate the port area and build a port to fit. in fiberglass i never get an accurate measurement of the inside volume since many spots have curves and such.

danphines
06-22-2009, 07:53 AM
fill it with water to measure volume

onemoremile
06-22-2009, 08:21 AM
Tang Band!

Jeff
06-22-2009, 09:05 AM
Tang Band!

Yes, it's a pretty popular brand amongst DIY enthusiasts. Very competitively priced and highest of quality. The funny thing is, this sub costs me about $40, and I found out that it is nearly IDENTICAL to the Elemental Designs 6.5" sub. The specs are exactly the same, but 1/4 of the cost.

Jeff
06-22-2009, 09:06 AM
fill it with water to measure volume

Exactly! Take a water bottle (which is 500ml), and start filling the box. This is the easy way, and perhaps the ONLY logical way.

Jeff
06-22-2009, 09:08 AM
is the box completely fiberglass? i'm pretty good at tuning a box when they are mdf but how would you tune it in fiberglass? in mdf i can just calculate the inside volume and then just calculate the port area and build a port to fit. in fiberglass i never get an accurate measurement of the inside volume since many spots have curves and such.

The baffle plate is birch plywood, due to it's strength over MDF, and weight. Get creative and use a water bottle by filling it until full. Since everything is covered in fiberglass, it is waterproof. If I had a lot of wood, then I would first put a plastic bag inside as a liner.

onemoremile
06-22-2009, 10:23 AM
MDF still works better due to it's resonant frequency. If water is too messy you can also use marbles, rice, styrofoam peanuts, etc..

Poopie
06-22-2009, 11:45 AM
damn thats a lot of fiberglass.I went with a small box that fits where the cd changer and tool kit used to go. Its about .5 cubic feet for a polk 8". Sounded pretty good till the seam above the hang developed a hairline crack and water ruined the mdf. I'll redo it some other time.

Jeff
06-22-2009, 01:50 PM
MDF still works better due to it's resonant frequency. If water is too messy you can also use marbles, rice, styrofoam peanuts, etc..

MDF and HDF (if you can find it) is still one of the best materials IMO. Some audiophiles may disagree, but their taste in music is also different.

In my case the wood (baltic birch) was 1/2" thick, and mainly used as a reinforcement piece for the baffle. The front and back of the wood was covered in 2 sheets of fiberglass. I used it primarily to give me a flat/solid surface to mount the driver.

Jeff
06-22-2009, 01:51 PM
damn thats a lot of fiberglass.I went with a small box that fits where the cd changer and tool kit used to go. Its about .5 cubic feet for a polk 8". Sounded pretty good till the seam above the hang developed a hairline crack and water ruined the mdf. I'll redo it some other time.

I use at least a minimum of 4 sheets on the corners/edges, and 6 sheets on flat surfaces. Cover the MDF with a layer of resin.