"JimH" wrote in message
...

"Jay" wrote in message ...
So I finally found a set of speakers that seemed like a good enough deal
and they came in last week. I'm wondering if anyone has any
input/experience installing speakers. They aren't flush mount which
needs I'll need to be cutting a few holes... some of my curiosity lies in
wondering if there's any certain saw blades one should use for cutting
fiberglass.... I was going to just drill a few holes to start a hand jig
saw... maybe tape up the area with duck tape to avoid scratching.. other
than that I didn't really know if there was anything one should take
precaution with.

Also, though they weigh a couple pounds each, should I worry much about
providing some of support to the backing... like a brace to dissipate
weight on the fiberglass walls?

TIA

-j


Always cover the face of the cut/drill area with duct tape...it reduces
the likelihood of the gelcoat chipping.

NEVER use duct tape for masking. When you remove it either the adhesive
will stay and is a bear to remove, or it will tear off any finish it was
applied
over. Use something like 3M blue tape.

You say these are not flushmount speakers so I assume they are already
installed in boxes and the brackets for the boxes are what you will be
attaching to the boat.

I would consider some sort of backing strap or plate the help support the
brackets. Large washers are another consideration.

"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...

"JimH" wrote in message
...

"Jay" wrote in message
...
So I finally found a set of speakers that seemed like a good enough deal
and they came in last week. I'm wondering if anyone has any
input/experience installing speakers. They aren't flush mount which
needs I'll need to be cutting a few holes... some of my curiosity lies
in wondering if there's any certain saw blades one should use for
cutting fiberglass.... I was going to just drill a few holes to start a
hand jig saw... maybe tape up the area with duck tape to avoid
scratching.. other than that I didn't really know if there was anything
one should take precaution with.

Also, though they weigh a couple pounds each, should I worry much about
providing some of support to the backing... like a brace to dissipate
weight on the fiberglass walls?

TIA

-j


Always cover the face of the cut/drill area with duct tape...it reduces
the likelihood of the gelcoat chipping.

NEVER use duct tape for masking.

You are correct. I should have said masking tape.

"Jay" wrote in message
...
Sorry, that was a bit uninformative..
They weigh about 2 or 3 pounds/piece. They didn't come with back braces,
and they would probably mount ok... my concern is the shock of slamming
over wakes over time, cracking the perimeter...

Get yourself a piece of 3/4" birch ply. Cut a square for each speaker, about
2" bigger than the speaker. Cut your holes in the fiberglass. Make them
perfect. Put the birch ply behind the holes you've made, trace the holes
onto the plywood, and cut holes in that, too. Actually, do that ***BEFORE***
you've cut it into squares. The big piece of ply will be easier to clamp to
a work surface than the smaller squares. Mount the speakers with the wooden
squares as bracing from behind.

One thing you didn't mention: What will be the enclosure BEHIND the
speakers? For any speaker, there's a very small range of correct enclosure
size. Get far from that range and the speaker becomes all but useless in
terms of bass response. Trying to get decent bass by dicking around with
tone controls will just overdrive your radio or amplifier, and blow up your
speakers in short order. Hint: In even the quietest cars, you need about 75
***CLEAN*** watts per channel to overcome road noise. If you intend to run
this stereo in a boat while the engine's running, you need about twice that
much power. Otherwise, you'd better be a big fan of distortion and blown
speakers.

Some folks recommend a minimum of 3 meters or ten feet
separation. Wouldn't hurt to conduct a test. Probably best
done with the boat out of the water so it can't move during
the test.

May not be a problem at all on a landlocked river, but other
readers might be more concerned about the effects of strong
onboard magnets on offshore navigation. Some modern speakers
have amazingly powerful magnets.







JimH wrote:
Those speakers are not magnetically shielded. That is not a problem as long
as you keep them away from the compass...e.g. 5 feet or so.


"Jay" wrote in message
...

They are, actually... though we're usually only on a landlocked river....

-j


"chuck" wrote in message
...

Before you cut into the boat, are the speakers magnetically shielded so
as not to interfere with your compass?

Jeff Morris wrote:

Jay wrote:

The birch idea sounds good..
Can't say I gave enclosures much though.. sounds like I need to though. .. .

-j


"Doug Kanter" wrote in message
...
"Jay" wrote in message
...
Sorry, that was a bit uninformative..
They weigh about 2 or 3 pounds/piece. They didn't come with back braces,
and they would probably mount ok... my concern is the shock of slamming
over wakes over time, cracking the perimeter...

Get yourself a piece of 3/4" birch ply. Cut a square for each speaker,
about 2" bigger than the speaker. Cut your holes in the fiberglass. Make
them perfect. Put the birch ply behind the holes you've made, trace the
holes onto the plywood, and cut holes in that, too. Actually, do that
***BEFORE*** you've cut it into squares. The big piece of ply will be
easier to clamp to a work surface than the smaller squares. Mount the
speakers with the wooden squares as bracing from behind.

One thing you didn't mention: What will be the enclosure BEHIND the
speakers? For any speaker, there's a very small range of correct enclosure
size. Get far from that range and the speaker becomes all but useless in
terms of bass response. Trying to get decent bass by dicking around with
tone controls will just overdrive your radio or amplifier, and blow up
your speakers in short order. Hint: In even the quietest cars, you need
about 75 ***CLEAN*** watts per channel to overcome road noise. If you
intend to run this stereo in a boat while the engine's running, you need
about twice that much power. Otherwise, you'd better be a big fan of
distortion and blown speakers.

Don't put the holes through the hull below waterline.

Just a thought

jofra

"Jofra" wrote in message
...
Don't put the holes through the hull below waterline.

Just a thought

jofra


I hope he doesn't put hole through the hull anywhere on the boat for this
speaker installation. ;-)

Might be a good idea to determine what's behind the bulkhead before
drilling and cutting. If you cut the hole accurately, you can use SS
wood screws in correctly sized holes to attach them.
JR
Jay wrote:

So I finally found a set of speakers that seemed like a good enough deal and
they came in last week. I'm wondering if anyone has any input/experience
installing speakers. They aren't flush mount which needs I'll need to be
cutting a few holes... some of my curiosity lies in wondering if there's any
certain saw blades one should use for cutting fiberglass.... I was going to
just drill a few holes to start a hand jig saw... maybe tape up the area
with duck tape to avoid scratching.. other than that I didn't really know if
there was anything one should take precaution with.

Also, though they weigh a couple pounds each, should I worry much about
providing some of support to the backing... like a brace to dissipate weight
on the fiberglass walls?

TIA

-j




--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth

Basic physics: take note of the distance sound leaving the rear surface of
the speaker has to travel through the air to reach the front of the speaker.
Any sound with a wavelength longer that this distance will cancel itself out
as the sound from the front is perfectly out of phase with the sound from
the rear. No bass in other words. An enclosure effectively creates an
infinite distance from front to rear as the two out of phase sound waves
can't get to each other. they are blocked form meeting by the walls of the
enclosure. If the enclosure is too small the speaker ends up using up most
of its power trying to compress the air inside the enclosure resulting in
little low bass as well. So the enclosure has to be both well sealed and
big enough to be effective. It is possible to vent an enclosure with a
tuned port (often called bass reflex) allowing a smaller enclosure but that
isn't simple physics any more...
--
Ken Heaton
Cape Breton Island, Canada
kenheaton AT ess wye dee DOT eastlink DOT ca


"Jay" wrote in message
...
The birch idea sounds good..
Can't say I gave enclosures much though.. sounds like I need to though. ..
..

-j


"Doug Kanter" wrote in message
...
"Jay" wrote in message
...
Sorry, that was a bit uninformative..
They weigh about 2 or 3 pounds/piece. They didn't come with back
braces,
and they would probably mount ok... my concern is the shock of slamming
over wakes over time, cracking the perimeter...

Get yourself a piece of 3/4" birch ply. Cut a square for each speaker,
about 2" bigger than the speaker. Cut your holes in the fiberglass. Make
them perfect. Put the birch ply behind the holes you've made, trace the
holes onto the plywood, and cut holes in that, too. Actually, do that
***BEFORE*** you've cut it into squares. The big piece of ply will be
easier to clamp to a work surface than the smaller squares. Mount the
speakers with the wooden squares as bracing from behind.

One thing you didn't mention: What will be the enclosure BEHIND the
speakers? For any speaker, there's a very small range of correct
enclosure
size. Get far from that range and the speaker becomes all but useless in
terms of bass response. Trying to get decent bass by dicking around with
tone controls will just overdrive your radio or amplifier, and blow up
your speakers in short order. Hint: In even the quietest cars, you need
about 75 ***CLEAN*** watts per channel to overcome road noise. If you
intend to run this stereo in a boat while the engine's running, you need
about twice that much power. Otherwise, you'd better be a big fan of
distortion and blown speakers.

Ken Heaton wrote:
Basic physics: take note of the distance sound leaving the rear surface of
the speaker has to travel through the air to reach the front of the speaker.
Any sound with a wavelength longer that this distance will cancel itself out
as the sound from the front is perfectly out of phase with the sound from
the rear. No bass in other words. An enclosure effectively creates an
infinite distance from front to rear as the two out of phase sound waves
can't get to each other. they are blocked form meeting by the walls of the
enclosure. If the enclosure is too small the speaker ends up using up most
of its power trying to compress the air inside the enclosure resulting in
little low bass as well. So the enclosure has to be both well sealed and
big enough to be effective. It is possible to vent an enclosure with a
tuned port (often called bass reflex) allowing a smaller enclosure but that
isn't simple physics any more...

Good explanation. It also helps to know the wavelengths. Sound travels
about 1127 ft/second in air and wavelength = velocity/frequency so...

freq. wavelength
(Hz) (ft)

20 56
40 28
80 14