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|8th July 2013, 12:14 AM||#1|
Join Date: Nov 2012
Fusion NV-SW 12 car sub closed
Welcome! This is my 2nd thread and another subwoofer project build. Having completed a previous LAB-12 home sub for a friend, I decided to come back to car audio, since having a hefty 12" collecting dust in the garage (FIRST ever box)!
This time I have ideas to add a bit of punch to my Land Rover. Tricky stuff, since the vehicle performs as a primary means of transportation, daily driver, work-horse, hunting and off-road use. Requirements for the sub are tight; needs to be no more than 1/3 of the boot space (tools, compressor, jumper cables, shovel, first aid kit, fire-extinguisher, tow rope) and still be able to put a suitcase , needs to be dis-mountable (hunting, load carrying, etc.) and needs to be sufficiently POWERFUL to provide pleasure sitting on traffic lights on the way to work !
The car has an average set-up to start with - 4 x 10 cm co-axials + 10" vented Audiobahn @ 250 W. Recently, I went for a roof re-upholster and have dismantled half the car. While waiting for the upholstery on the roof, I insulated the roof area with STP Biplast 5mm and WOW, the existing set up came to life!
I have a Fusion Audio NV-SW12, which I had numerous problems with, however it was my first ever DIY sub! Currently it sits quiet, collecting dust in the garage for over a year, following 2 repairs (voice coil misaligned)! So, being extremely happy of how the current set-up came to life after the STP Biplast insulation, I decided to make a new box for the Fusion and also go for 16.5 cm rear speakers! I'm working my way down from the roof fixing all metal work and applying various insulating materials (primarily thermal, they didn't call it LR Discovery for no reason!).
I listen to Drum n Bass music, which is very fast, has low extension and overwhelms with fast, low-frequency beats. I have designed vented boxes since I started with DIY boxes, however this time I decided to try a closed box for a change!
I know that closed boxes are usually dampened a lot more than vented boxes, so I decided to post my contemplations on what a closed box for the Fusion NV-SW12 would look like.
I'm looking at a 65 liter box, netting Vb of 49-51 liters after subtracting bracing and dampening material and sub volume.
Now, I have a few questions which I'm not sure I'm answering correctly:
1) How different is the response (car audio) of closed vs. vented box? I get an F3 of around 43 Hz, tuned @ 37 Hz for the closed box. How different will it be from the traditional vented set-ups (current vented box is tuned @ 30 Hz, 10" AW101T)
2) How critical is dampening? I'm still thinking of WHY to spend 85 euro on insulation material alone (car insulation material)! I'm thinking of combining 2 different materials ( STP Bomb & Silent Coat Sound Absorber 35mm) as dampening material inside the box.
I checked calculations of the closed box, using Unibox408, WinISD and Bass Box Pro 6. Apart from BB 6, the other 2 calcs give pretty much identical results. I don't have equipment to measure the driver, so I'm going with listed specs. And here comes the troubles! The sub was defective since day 1, granted it had to fly cargo UK - Bulgaria, was initially wired @ 1 ohm (2x2ohm), but had a scratchy sound when music played. Later I was told the VC was mis-aligned and not glued from the factory (2nd repair)!
My worries are really dampening the box and making sure its SEALED properly! I have designed the box with bracing, however I'm not sure on how the dampening material will behave inside the box, will it work as intended!?! The overall weight with MDF, Sub & Dampening material gets to about ~75-80 kg (excluding exterior finish)! I also normally epoxy my boxes from the inside!
But enough words, bring on the specs and pics:
Sub (2x 2ohm) - http://www.vbc-group.com/ebay/NV%20S...r%20Manual.pdf
1st layer - StP - STP BOMB
2nd layer - Silent Coat Absorber 35 | Silent Coat UK
Box size - W 52cm x H 42.8cm x D 40cm (19mm MDF, double front, brace extends 40mm - 4.2mm STP Bomb + 35mm Silent Coat Absorber)
|8th July 2013, 03:36 AM||#2|
Join Date: Feb 2006
I can show you what car gain can do for the vented F3 = 10Hz driver below (10dB correction for 4cuMeters car).
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