WTB 8" Under the dash custom Subwoofer Box (Page 2/22)
FieroJonney AUG 11, 09:41 PM
I just purchased an 8" under the dash box from Vendetta, thanks everyone.
FieroJonney AUG 11, 09:51 PM
Fred, I'm definitely interested in purchasing one of those! But it'll have to wait till next summer.
I've only got two and a half months left of driving the fiero, so I wanted a quick purchase.
Good luck with your product, looks amazing.
mid engine monsters AUG 11, 10:05 PM
what happens in 2 1/2 months ,you going away?
FieroJonney AUG 11, 10:18 PM
end of October and I'm putting storage ins. on it.
I only get to drive it for half the year </3 Michigan weather
winter is longer than summer here! grrr it sucks
Black Pegasus AUG 12, 01:34 AM
No problem! At the end, I can't force you to buy it! lol

I'll keep on working on it. I'll try to keep everyone informed about it!

Fred

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87 Pontiac Fiero GT

Austrian Import AUG 12, 03:37 AM
I really like this setup!

A couple questions: Will it work with Fierosound's 5 1/4" Component adapter plate + component speakers? What depth would I have available?
At the risk of it sounding like a stupid question: Why wouldn't a 10" speaker fit? Where exactly is the problem? (different angle maybe? little closer into the footwell?) Please explain it a bit.
What would the odd shape do to harmonics and sound? Better?, Worse?
What exactly is the air volume? (if you haven't tested it, Water, and/or small pellets could help you measure the volume of this odd shape)
Rixthetrick AUG 12, 05:27 AM
G'day from Australia.
Have you considered using dowel/s to cross brace the box?
If you play with a few different configurations of bracing to find an optimum,
you may find it "deadens" the energy that the fibreglass box will absorb which then
causes the box to vibrate, producing a sound that is not as accurate.

Also as it appears that no porting is designed in this box (which would be driver specific
if you did port). You could try using a high grade, audio specific foam product that will
dampen internal standing waves in the box.
Damping of the internal air mass is critical in controlling the air flow
from the bass driver - affecting bass extension and the speed of the midrange.

If you have the correct driver for the volume of the box, well sorted bracing, good thickness
of the walls in the box, and suitable acoustic foam, you may not have the bass of a tuned
ported enclosure, but you aught to get a clean midbass and bass from an 8" driver.
Of course, the crossover in this circuit with good inductors or if it's an active crossover
into a suitably powerful and accurate amplifier will make the world of difference,
to handle dampening on the 8" driver.

All the best,
Rick
Black Pegasus AUG 13, 11:08 AM
Austrian Import,

For the Fierosound's 5 1/4" Component adapter plate with the component speakers, I don't know if they will fit. I don't have this kit/modification on hand so I can't try to fit the enclosure. From what I can see, it appears that it may fit but I can't say for sure. Sorry...

I could not fit a 10" speaker in there. As you can see from the pictures, the space is very limited. The problem was with the combination of diameter / dept and angle of the various 8" subwoofers, we actually had to make a lot of modifications just to allow the fitting of a second type of 8" subwoofer (a choice between shallow or a normal sub). It is impossible to put a 10" under there because of its diameter. The space is just not big enough to mount it (unless you want to cut out your dash and / or the heater’s "duc work" to allow extra clearance) or by bringing it down even more and make like a conic shape to have a bigger hole. An other reason is that, once again, the space is very limited, therefore most 10" subwoofer may not have enough air volume in the enclosure to work properly (There will be too much air resistance therefore you will need more power to drive the subwoofer... The efficiency will go down below acceptable standards). For the amount of space under the dash, an 8" is the biggest thing I can put while staying within the project guidelines.

Rixthetrick is absolutely right. I have not tested if the box shape will change the harmonics significantly. But I do not expect any problem in that area. The only problem that I can see with the fact that the enclosure has a weird shape is the air flow within the box itself. If the air moves rapidly around bumps inside the box, there may be a whistling sound generated by the air movement. This can be easily taken care of with some strategically positioned polyfill damping material. Keep in mind that all woofers will work differently in a given enclosure. The woofer relies (at least partly) on the enclosure for damping. A lot of people just go to a local audio store, pick up a subwoofer and a box, install the subwoofer in the box, connect their power amp and go. This works and often yields good results.

However, if you are looking for optimum performance, this box will be no different than any other box, you will have to pick up a subwoofer that operates within the air displacement availability of the box AND will need to “tune” your subwoofer / enclosure combination to the type of music that you listen (by damping the enclosure as required for your combination).

As for the volume of the enclosure, there is currently no way for me to know the exact amount. What was pictured above is not yet a working model of the enclosure, it's a pre mold model. We made quite a few modifications to the model by adding putty to ensure that both of our subs fit AND to capture the maximum available space under the dash. Therefore we added putty over the existing fiberglass pieces. This means that in some portion of the enclosure, the "walls" of might be as thin as 1/8 inches and some other portions might be as thick as 1 inch!
For this reason it is impossible for me to get an accurate volume reading by putting the enclosure in water because it will show the exact exterior volume, this will have a higher volume than the air volume inside the enclosure (Because it will be the exterior volume, it doesn't account for the material thickness I will be using). Plus we may have to add some extra strategically positioned reinforcements inside the enclosure to "tune" the enclosure's reverberation (vibration).
I can't pour water inside the enclosure because it was HEAVILY modified. Having that much variation in the enclosure "walls" won't even yield a volume estimation.
Basically, I can't give a proper volume estimation until I have a "close to final" product, and the volume won't be exactly the same from one subwoofer enclosure to the next (because of the variation in thickness of resin and fiberglass used when laying the enclosure). Though, I'll make sure to have nice layers of fiberglass to have the strength needed to withstand the force of the subwoofer.

If you guys have any other questions, I will try to help you the best I can!

Fred

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87 Pontiac Fiero GT

Austrian Import AUG 14, 04:03 PM
Black Pegasus, sounds like an exiting project. Can't wait to see (and hear) the results. Keep us in the loop.
Which subwoofers are you tuning/designing this box for?

Since this box is so huge it might allow for some medium/high end subs as well. (This will make things easier down the road once the medium/high end speakers drop in price)

As to Fierosounds 5 1/4" enclosure: See if you could contact him, or one of the many members that have it installed to give you the measurements necessary. I'm assuming that the only problem will be depth (or where the depth would be) You could probably make a mockup out of cardboard and use it as a template to make your measurements from. (It's a Word document anyhow)

Keep in mind some medium/high end drivers, such as Polk SR-series, Infinity Reference, Alpine R-Series, maybe even Focal (although they tend to be priced above and somewhat tinny sounding) Since most high end drivers tend to be bigger than normal drivers, that should give you plenty of slack to work with.

Please also post some info about "tuning" with Polyfill, or special material once time comes.
Rixthetrick AUG 14, 08:34 PM
Try pouring rice into the enclosure, it will give you the internal volume without creating
whatever issues water would have on a fibreglass box???
Also if you're worried about whatever you're bracing getting waterlogged -
paint it with resin, I usually do that with dowel anyway.
Are you thinking of lining the box with something affected by water (moisture)?

Poly wool will not nearly give you the same results as properly designed denser "sticky foam".
Which you can hold up to your mouth and talk through it, and a second person can audibly
discern a difference in pitch. If you can't hear a difference in pitch in the product you're
going to use, I assure you there are products that will, and absolutely make a difference.
More so to the lower midbass than the lower inaudible frequencies.

Yesterday I found a solution I have chosen to run with, after I source it
for the best possible price. Of course it's my best compromise, my car is Right Hand Drive to meet
Australian rules. The area this box fits has all been changed in my particular car. Therefore
I couldn't possibly use this sub box; otherwise I'd be lining up to give it a try.

All the best with your product,
Rick - Downunder