Having just decided I need a subwoofer for below deck in a 42' sailboat,
I've just spent the past several hours browsing the newsgroups, google
groups search of subwoofer. Now, I'm more confused than before, but getting
quite educated. My current configuration is an Alpine 7894 powering a pair
of 4x6" speakers in the main cabin, about 15' x 13' x 7' (about 1400 cubic
feet). I know an amp, subwoofer & enclosure are needed, and would like the
following specific questions:

1. Am I correct in assuming a particle board enclosure, sealed by varnishing
inside & out would be best, carpet is not important?
2. Is 1/2" thick sufficient, or do I need 3/4"?
3. How important is the size? I will make a custom box & keep it below a
bench, cutting out a hole the diameter of the
driver.
4. Do I need a certain dimension box? Is the importance in total cubic feet
or a specific ratio of dimensions? There is very limited debth in this
bench, therefore, if I need a certain cubic foot size, could the box be
quite wide, and very shalow to get that quantity of feet?
5. Do you think a 10" driver would be sufficient, don't have room for 12".
6. Am I correct in assuming 1 speaker pointed toward the center of the cabin
should be sufficient?
7. Am I correct in assuming 100 RMS watt amp would be sufficient, it pretty
much is an enclosed cabin, or is that quite an
overkill?
8. Am I correct in assuming I shouldn't need any equalizer, nor filter?
9. Any recommendation for a decent medium priced driver, amp? Problem is I
won't be able to hear my speaker, enclosure, amp until it's all built, which
may be too late.

Where could I get a white grill that's pretty strong, as someone may
accidently kick it? All I see are black ones, rest of cabin is white.

Btw, my email actually ends in 101.
Thanks,

Norm

1. Am I correct in assuming a particle board enclosure, sealed by varnishing
inside & out would be best, carpet is not important?

Change particle board to MDF and your good. Since you are in a boat and their
is a chance of getting it wet definantly seal it like you talked about.

2. Is 1/2" thick sufficient, or do I need 3/4"?

3/4 Definantly

3. How important is the size? I will make a custom box & keep it below a
bench, cutting out a hole the diameter of the
driver.

Important enough to get it right. Most companies provide a reccommended box
size.

4. Do I need a certain dimension box? Is the importance in total cubic feet
or a specific ratio of dimensions?

Cubic Feet typically. Box shape is unimportant.

There is very limited debth in this
bench, therefore, if I need a certain cubic foot size, could the box be
quite wide, and very shalow to get that quantity of feet?

Yes as long as the total cubic feet are the same.

5. Do you think a 10" driver would be sufficient, don't have room for 12".

What is limiting the use of the 12"? Is the bench only 10" high? The right ten
in the right box can get loud enough.

6. Am I correct in assuming 1 speaker pointed toward the center of the cabin
should be sufficient?

Probably

7. Am I correct in assuming 100 RMS watt amp would be sufficient, it pretty
much is an enclosed cabin, or is that quite an
overkill?

That would be the minimum I would use. But it should be enough.

8. Am I correct in assuming I shouldn't need any equalizer, nor filter?

You will need a low pass filter. Get an amp that has one built in.

9. Any recommendation for a decent medium priced driver, amp? Problem is I
won't be able to hear my speaker, enclosure, amp until it's all built, which
may be too late.

What is medium priced to you? I personally like Image Dynamics IDQ series. Look
on Ebay. For an amp check out Memphis cheaper USAcoustics. Again Ebay.

Where could I get a white grill that's pretty strong, as someone may
accidently kick it? All I see are black ones, rest of cabin is white.


Get a black one and paint it white.

Suggestion/question. Don't you have an inverter on that boat? If so why dont
you look into getting a home theatre type subwoofer. You can get one for the
same cost as a seperate amp, speaker, and box and I can see no reason why it
shouldnt perform well. Your only problem is finding a place to put it.

Les

Ive never installed a boat before, but heres what I know...
Garrett

Captain Norm wrote:

Having just decided I need a subwoofer for below deck in a 42' sailboat,
I've just spent the past several hours browsing the newsgroups, google
groups search of subwoofer. Now, I'm more confused than before, but getting
quite educated. My current configuration is an Alpine 7894 powering a pair
of 4x6" speakers in the main cabin, about 15' x 13' x 7' (about 1400 cubic
feet). I know an amp, subwoofer & enclosure are needed, and would like the
following specific questions:

1. Am I correct in assuming a particle board enclosure, sealed by varnishing
inside & out would be best, carpet is not important?
2. Is 1/2" thick sufficient, or do I need 3/4"?

Theoretically MDF is ideal. Although I am using 5/8 particle board and
I fiberglassed the inside of the box. IMHO 5/8" thickness will suffice
for a 10" at 100 watts RMS. Use liquid nails and zinc coated 2" drywall
screws.

3. How important is the size? I will make a custom box & keep it below a
bench, cutting out a hole the diameter of the
driver.

enclosure size is critical. A cheap driver in a well designed enclosure
will outperform an expenseive driver in a poorly designed enclosure.
IMHO driver size is less critical now days with all the high excursion
subs. Ive read about several DB draggers hitting 137db on a pair of
kicker 8"L7 solobarics.

4. Do I need a certain dimension box? Is the importance in total cubic feet
or a specific ratio of dimensions? There is very limited debth in this
bench, therefore, if I need a certain cubic foot size, could the box be
quite wide, and very shalow to get that quantity of feet?

Yes... enclosure volume is critical to subwoofer performance. There is
a theoretical "golden ratio" LxWxH that many DIY'ers use to build their
enclosures. But I forget what it is... I usually build near-cube
shaped enclosures.

5. Do you think a 10" driver would be sufficient, don't have room for 12".

Depends on your budget. A single Adire Brahma 10" can get rediculously
loud in the proper enclosure. A pyramid hyper pro should max out about
125db in a proper enclosure.

6. Am I correct in assuming 1 speaker pointed toward the center of the cabin
should be sufficient?

Experiment. It depends on the room acoustics and resonant
characteristics of the listening environment. Many home subs point to
the floor. I think the theory here is to excite room resonance and get
the air volume of the listening environment to resonate at its resonant
freq.

7. Am I correct in assuming 100 RMS watt amp would be sufficient, it pretty
much is an enclosed cabin, or is that quite an
overkill?

100 RMS Should be plenty IMHO, Im assuming the ambient noise on a boat
is pretty low. But then again it depends on your listening habbits and
how loud you like your music.

8. Am I correct in assuming I shouldn't need any equalizer, nor filter?

You will need a low pass filter, preferably a line level filter. Many
amps have built in low pass filters.

9. Any recommendation for a decent medium priced driver, amp? Problem is I
won't be able to hear my speaker, enclosure, amp until it's all built, which
may be too late.

Thats the fun part... You never know exactly how it will sound until you
install it.
Whats your budget?

Pyramid Hyper Pros are great budget subs made by Eminence and
re-badged. Dont believe all the neg hype about Pyramid, they have some
good gear and some crap just like everyone else. around $30 new on
ebay. Ive been pounding the snot out of my BOSS rip-12Cs and they so
far are durable. I think they make a 10" version. About $30 new ebay.

IMHO Alpine Type-Rs are also good as well as infinity kappas. around
$90 new ebay

Adire Brahma, Digital designs, Image dynamics ID MAX, and Licker L7s are
at the high end if you want to splurge.

US acoustics and Visonik are great amps for the $$$. Ive been using a
profile CA series and its been great/reliable.


Where could I get a white grill that's pretty strong, as someone may
accidently kick it? All I see are black ones, rest of cabin is white.


Parts express may have some, or you could spraypaint one.

Btw, my email actually ends in 101.
Thanks,

Norm