Speaker box question

On Mon, 12 Jul 2004 12:43:13 -0400, Jay Pique <[email protected]>
wrote:
> On Mon, 12 Jul 2004 14:50:12 GMT, "U-CDK_CHARLES\\Charles" <"Charles
> Krug"@cdksystems.com> wrote:
>
>>On Sat, 10 Jul 2004 18:07:55 -0400, Jay Pique <[email protected]> wrote:
>>> On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:
>>>
>>>>
>>>>"Edwin Pawlowski" wrote in message
>>>>
>>>>> OK, now for the questions. The front I plan to make a straight vertical
>>>>> strip about 2" high and then set the face at about 15 degrees. Any reason
>>>>> not to? Speakers will be mounted side by side.
>>>>>
>>>>> I'm planning to use biscuits and glue it together.
>>>>
>>>>Personally, I would use rabbet joints, glue and screws on speaker boxes ...
>>>>most of the top end speakers are made this way.
>>>
>>> Would lock miters be as strong here? Any benefit? I'm just not sure
>>> of the usefulness of screws in MDF. If the glue joint fails it seems
>>> the screws would give loose too.
>>>
>>
>>I've an old "how to make your box" book from JBL--probably still on
>>their website, as they still make "E-Series" components.
>>
>>They specifically recommend lock mitres AND glue blocks.
>
> But screws or no screws?
>

Screws, both in the book and in my cabs.

CW apparently said,on my timestamp of 13/07/2004 1:22 PM:

> Glue and screw MDF together. If you drill proper pilot holes, screws hold
> great. Not that they real have to hold anything. Glue a couple pieces of MDF
> together with Titebond sometime then take a hammer to it. You will pulverize
> the MDF before that glue joint fails.

and do NOT forget to drill the pilot holes. MDF doesn't like
screws driven into it point blank. DAMHIKT...

--
Cheers
Nuno Souto
[email protected]

Edwin Pawlowski apparently said,on my timestamp of 13/07/2004 1:10 PM:

> "Elwood Dowd" <[email protected]> wrote in message
>
>>The book I eventually purchased is called "Speakers for your Home and
>>Automobile" by Gordon McComb, Alvis J. Evans, and Eric J. Evans.
>>
>>Don't forget air ports. Subwoofers need a lot of air, and they can be
>>damaged by the pressure difference between inside and outside at higher
>>volumes. (Don't ask me how I know)
>>
>>Also, rather than fiberfill inside, I have found that carpet scraps work
>>wonderfully and are almost free. And probably easier to use than the cat.
>
>
> I'll have to look it up if I make another. This has been interesting once I
> got into it a bit. Lots more to it than meets the eye first time out.
> Ed
>
>


"The Loudspeaker Design Cookbook". Vance Dickason.
Sixth Edition, Oct 2000.
ISBN: 1-882580-33-8

Warning: it's a slippery slope. You'll find yourself trying
this, then that, then the other, then one more bit, etcetcetc.......

--
Cheers
Nuno Souto
[email protected]

On Mon, 12 Jul 2004 18:02:37 GMT, "U-CDK_CHARLES\\Charles" <"Charles
Krug"@cdksystems.com> wrote:

>On Mon, 12 Jul 2004 12:43:13 -0400, Jay Pique <[email protected]>
>wrote:
>> On Mon, 12 Jul 2004 14:50:12 GMT, "U-CDK_CHARLES\\Charles" <"Charles
>> Krug"@cdksystems.com> wrote:
>>
>>>On Sat, 10 Jul 2004 18:07:55 -0400, Jay Pique <[email protected]> wrote:
>>>> On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:
>>>>
>>>>>
>>>>>"Edwin Pawlowski" wrote in message
>>>>>
>>>>>> OK, now for the questions. The front I plan to make a straight vertical
>>>>>> strip about 2" high and then set the face at about 15 degrees. Any reason
>>>>>> not to? Speakers will be mounted side by side.
>>>>>>
>>>>>> I'm planning to use biscuits and glue it together.
>>>>>
>>>>>Personally, I would use rabbet joints, glue and screws on speaker boxes ...
>>>>>most of the top end speakers are made this way.
>>>>
>>>> Would lock miters be as strong here? Any benefit? I'm just not sure
>>>> of the usefulness of screws in MDF. If the glue joint fails it seems
>>>> the screws would give loose too.
>>>>
>>>
>>>I've an old "how to make your box" book from JBL--probably still on
>>>their website, as they still make "E-Series" components.
>>>
>>>They specifically recommend lock mitres AND glue blocks.
>>
>> But screws or no screws?
>>
>
>Screws, both in the book and in my cabs.

Well whattaya know. Thanks for the info.

JP
**************
Screwed.

Edwin Pawlowski wrote:

> "Leon" <[email protected]> wrote in message
>
>>Normally a car with these type speakers can be heard half a block away
>>because of all the ratteling sheet metal.
>>
>>Well maybe my suggestions would take all the fun out of having a car that
>>shakes, rattles, and rolls when the radio is on. :~) Savor the time you
>>spend with your grandson. I hope to have one in about 10 to 15 years.
>
>
> I'm sure the neighbors will appreciate your suggestions.
>


Actually yes, they will.

That obscene noise you hear isn't from inside the car , it's from the frigging
vibrating body panels. Keeping the panels from shaking keeps the 'Hood from waking.

--

Mark

N.E. Ohio

In theory there is no difference between theory and practice, but in practice
there is.

Never argue with a fool, a bystander can't tell you apart. (S. Clemens, A.K.A.
Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the suspense.
(Gaz, r.moto)

On Tue, 13 Jul 2004 23:45:21 GMT, Old Nick <[email protected]> wrote:
> On Tue, 13 Jul 2004 11:01:52 GMT, B a r r y
><[email protected]> vaguely proposed a theory
> ......and in reply I say!:
>
> remove ns from my header address to reply via email
>
>
>>Depends on the speaker. Some are designed for sealed boxes, some for
>>ported. Check the specs.
>
> OK. Thought it over. I had always assumed that the reccommended box
> was to do with sound characteristics, not the ddanger of blowing
> cones. This has always been born out for me by the fact that some
> speakers just sound like shit in a vented/closed etc enclosure.
>>
>>I've also seen speakers blown the way you describe, but it had nothing
>>to do with the box. A subsonic noise component drove them right out
>>of the baskets. <G>
>
> Popping the cone...no that has another meaning altogether, IIRC.
>
> It would have _something to do with the box, surely. The back-pressure
> in a sealed enclosure _may_ have saved that one time.
>
> I do remember that stage speakers have a completely different
> magnet/coil setup, so that the coil moves out of the magnetic field
> before the coil pops out of the basket.

Stage speaker drivers are, as a rule are a good bit less efficient than
home speakers. Recorded music is massaged and compressed, and never has
things like 120dB accidental feedback, not to mention live uncompressed
drums.

If you connect your 1200W stage stack to your home receiver, you'll be
impressed by how little volume you get, and how muddy it sounds (to be
pedantic, you'd usually need a passive crossover to do this).

OTOH, if you connect your "100W Peak Power" home stereo speakers to an
inexpensive 50W guitar amp, you'll be impressed at the bright colors and
the smell of the smoke.

DAMHIKT

On Tue, 13 Jul 2004 11:01:52 GMT, B a r r y
<[email protected]> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

Third time the bass drum hit. Honky Tonk Woman...

phph phph-phph phph phph phph phph phph-phph phph....

>I've also seen speakers blown the way you describe, but it had nothing
>to do with the box. A subsonic noise component drove them right out
>of the baskets. <G>
>
>Barry

"U-CDK_CHARLES\Charles" <"Charles Krug"@cdksystems.com> wrote in message
> >
>
> I've an old "how to make your box" book from JBL--probably still on
> their website, as they still make "E-Series" components.
>
> They specifically recommend lock mitres AND glue blocks.

Too late for that. Already cut the rabbets.

>
> I've had good results just using glue block reinforced joints, and
> running a bead of caulk along all the seams.
>
>
OK, I can do glue blocks.
Ed

"Swingman" <[email protected]> wrote in message
>
> Personally, I would use rabbet joints, glue and screws on speaker boxes
...
> most of the top end speakers are made this way.
>

Yeah, I start some of these projects with the idea of a quick and simple box
to keep the kid happy, but end up trying to make the perfect piece of
furniture/equipment, etc. Pays to do a class job from the beginning.
Ed

On Sat, 10 Jul 2004 18:07:55 -0400, Jay Pique <[email protected]> wrote:
> On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:
>
>>
>>"Edwin Pawlowski" wrote in message
>>
>>> OK, now for the questions. The front I plan to make a straight vertical
>>> strip about 2" high and then set the face at about 15 degrees. Any reason
>>> not to? Speakers will be mounted side by side.
>>>
>>> I'm planning to use biscuits and glue it together.
>>
>>Personally, I would use rabbet joints, glue and screws on speaker boxes ...
>>most of the top end speakers are made this way.
>
> Would lock miters be as strong here? Any benefit? I'm just not sure
> of the usefulness of screws in MDF. If the glue joint fails it seems
> the screws would give loose too.
>

I've an old "how to make your box" book from JBL--probably still on
their website, as they still make "E-Series" components.

They specifically recommend lock mitres AND glue blocks.

I've had good results just using glue block reinforced joints, and
running a bead of caulk along all the seams.

Lock mitres require a shaper, (I've seen router bits, but it seems a bit
hefty a job for a router table) which I don't have.

On Sat, 10 Jul 2004 19:53:13 GMT, Edwin Pawlowski <[email protected]> wrote:
> I'm building a speaker box at the request of my grandson. With information
> from a thread long ago and excellent information supplied by Dean Reece, I'm
> somewhat prepared to start. I'm not prepared to listen to them once
> installed, but that is a whole 'nuther story.
>
> Speakers are Infinity 12.1 12" woofers. Box will be 3/4" MDF lined with
> fiberfill. I have a sketch from Nathan that shows an angled front, about
> 16" high, 16" deep at the base, 12" deep at the top. It is 36" long. It will
> be a sealed box with no port.
>

DAGS for "winISD." Download and install the "beta" version.

Get the "Theile/Small" parameters from the manufacturers website if it's
not already in the database.

That program has TONS of information about how to make the box.

For materials, High Density Fibreboard is often recommended by
driver manufacturers, but of course it can't get wet. Void-free birch
ply is probably Good Enough.

You need to line the box with at least an inch of something fluffy. A
roll of 3-1/2" fibreglass is, again, probably Good Enough.

"U-CDK_CHARLES\Charles" <"Charles Krug"@cdksystems.com> wrote in message
>
> DAGS for "winISD." Download and install the "beta" version.
>
> Get the "Theile/Small" parameters from the manufacturers website if it's
> not already in the database.
>
> That program has TONS of information about how to make the box.
>

Got it. I don't yet fully understand it, but I can figure it out. I have
to get more information as to the actual equipment.
Thanks,
Ed

"Leon" <[email protected]> wrote in message
>
> Normally a car with these type speakers can be heard half a block away
> because of all the ratteling sheet metal.
>
> Well maybe my suggestions would take all the fun out of having a car that
> shakes, rattles, and rolls when the radio is on. :~) Savor the time you
> spend with your grandson. I hope to have one in about 10 to 15 years.

I'm sure the neighbors will appreciate your suggestions.

On Mon, 12 Jul 2004 14:50:12 GMT, "U-CDK_CHARLES\\Charles" <"Charles
Krug"@cdksystems.com> wrote:

>On Sat, 10 Jul 2004 18:07:55 -0400, Jay Pique <[email protected]> wrote:
>> On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:
>>
>>>
>>>"Edwin Pawlowski" wrote in message
>>>
>>>> OK, now for the questions. The front I plan to make a straight vertical
>>>> strip about 2" high and then set the face at about 15 degrees. Any reason
>>>> not to? Speakers will be mounted side by side.
>>>>
>>>> I'm planning to use biscuits and glue it together.
>>>
>>>Personally, I would use rabbet joints, glue and screws on speaker boxes ...
>>>most of the top end speakers are made this way.
>>
>> Would lock miters be as strong here? Any benefit? I'm just not sure
>> of the usefulness of screws in MDF. If the glue joint fails it seems
>> the screws would give loose too.
>>
>
>I've an old "how to make your box" book from JBL--probably still on
>their website, as they still make "E-Series" components.
>
>They specifically recommend lock mitres AND glue blocks.

But screws or no screws?

>I've had good results just using glue block reinforced joints, and
>running a bead of caulk along all the seams.

>Lock mitres require a shaper, (I've seen router bits, but it seems a bit
>hefty a job for a router table) which I don't have.

I see lock miter bits sold for the router from almost every
manufacturer. Anyone else have bad experiences in router tables?

JP

Old Nick wrote:


>
> Can you describe that? Serious. I have seen speakers blown by too
> _little_ back pressure (over excursion) caused by ducts.
>
> What happened?


Too much power for too small of a magnet.?


--
{neatly edited}
--

Mark

N.E. Ohio

In theory there is no difference between theory and practice, but in practice
there is.

Never argue with a fool, a bystander can't tell you apart. (S. Clemens, A.K.A.
Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the suspense.
(Gaz, r.moto)

On Mon, 12 Jul 2004 13:19:41 -0500, Elwood Dowd <[email protected]> vaguely
proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>Don't forget air ports. Subwoofers need a lot of air, and they can be
>damaged by the pressure difference between inside and outside at higher
>volumes. (Don't ask me how I know)

Can you describe that? Serious. I have seen speakers blown by too
_little_ back pressure (over excursion) caused by ducts.

What happened?

On Wed, 14 Jul 2004 14:27:15 GMT, "U-CDK_CHARLES\\Charles" <"Charles
Krug"@cdksystems.com> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

I once tried (and gave up) to fix a 5watt per channel home stereo into
which the guy had plugged the speaker output from his guitar amp to
get a better sound....

>OTOH, if you connect your "100W Peak Power" home stereo speakers to an
>inexpensive 50W guitar amp, you'll be impressed at the bright colors and
>the smell of the smoke.
>
>DAMHIKT
>
>

"Edwin Pawlowski" wrote in message

> OK, now for the questions. The front I plan to make a straight vertical
> strip about 2" high and then set the face at about 15 degrees. Any reason
> not to? Speakers will be mounted side by side.
>
> I'm planning to use biscuits and glue it together.

Personally, I would use rabbet joints, glue and screws on speaker boxes ...
most of the top end speakers are made this way.

Should I make one of the
> panels in two pieces, leaving a section unglued for access to wires? I'd
> just screw it in place and use some sort of gasket material.

Probably not necessary. You can generally access the wires and mounting
plate, crossovers, etc through the opening for the speaker itself.

--
www.e-woodshop.net
Last update: 5/15/04

On Tue, 13 Jul 2004 03:46:26 GMT, Old Nick <[email protected]>
wrote:

>On Mon, 12 Jul 2004 13:19:41 -0500, Elwood Dowd <[email protected]> vaguely
>proposed a theory
>......and in reply I say!:
>
> remove ns from my header address to reply via email
>
>>Don't forget air ports. Subwoofers need a lot of air, and they can be
>>damaged by the pressure difference between inside and outside at higher
>>volumes. (Don't ask me how I know)
>
>Can you describe that? Serious. I have seen speakers blown by too
>_little_ back pressure (over excursion) caused by ducts.
>
>What happened?


Depends on the speaker. Some are designed for sealed boxes, some for
ported. Check the specs.

I've also seen speakers blown the way you describe, but it had nothing
to do with the box. A subsonic noise component drove them right out
of the baskets. <G>

Barry

On Tue, 13 Jul 2004 06:18:29 -0500, "Swingman" <[email protected]>
vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

>Driver design ... some drivers are designed to be ported, others not. There
>is a good deal of magic/art in correct porting of a specific driver for a
>certain sound and the size of the box, despite the physics involved and the
>manufacturer's recommendations.

Yep. everything to spec, and it still sounds not right.

>I used to build my bass cabinets based on
>the old Dietz design, which was a favorite for bass players in the "old
>days" and I experimented with many different porting sizes and designs on
>most of them ... AAMOF, I still play through an old Altec 15" bass speaker
>in an original Dietz box that I customized the porting on..

I once designed and built some horn-loaded, vented bass speakers for a
PA, using some JBL 15" drivers. It was as efficient as all hell, and
actually sounded good.

I do reckon that a lot of problems with home-built systems are cheap
drivers, trying to get good bass. Doesn't matter what you do.

Glue and screw MDF together. If you drill proper pilot holes, screws hold
great. Not that they real have to hold anything. Glue a couple pieces of MDF
together with Titebond sometime then take a hammer to it. You will pulverize
the MDF before that glue joint fails.

"Jay Pique" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 12 Jul 2004 14:50:12 GMT, "U-CDK_CHARLES\\Charles" <"Charles
> Krug"@cdksystems.com> wrote:
>
> >On Sat, 10 Jul 2004 18:07:55 -0400, Jay Pique <[email protected]>
wrote:
> >> On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:
> >>
> >>>
> >>>"Edwin Pawlowski" wrote in message
> >>>
> >>>> OK, now for the questions. The front I plan to make a straight
vertical
> >>>> strip about 2" high and then set the face at about 15 degrees. Any
reason
> >>>> not to? Speakers will be mounted side by side.
> >>>>
> >>>> I'm planning to use biscuits and glue it together.
> >>>
> >>>Personally, I would use rabbet joints, glue and screws on speaker boxes
...
> >>>most of the top end speakers are made this way.
> >>
> >> Would lock miters be as strong here? Any benefit? I'm just not sure
> >> of the usefulness of screws in MDF. If the glue joint fails it seems
> >> the screws would give loose too.
> >>
> >
> >I've an old "how to make your box" book from JBL--probably still on
> >their website, as they still make "E-Series" components.
> >
> >They specifically recommend lock mitres AND glue blocks.
>
> But screws or no screws?
>
> >I've had good results just using glue block reinforced joints, and
> >running a bead of caulk along all the seams.
>
> >Lock mitres require a shaper, (I've seen router bits, but it seems a bit
> >hefty a job for a router table) which I don't have.
>
> I see lock miter bits sold for the router from almost every
> manufacturer. Anyone else have bad experiences in router tables?
>
> JP

On Tue, 13 Jul 2004 11:01:52 GMT, B a r r y
<[email protected]> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

hmm..ok. Thanks.

>Depends on the speaker. Some are designed for sealed boxes, some for
>ported. Check the specs.
>
>I've also seen speakers blown the way you describe, but it had nothing
>to do with the box. A subsonic noise component drove them right out
>of the baskets. <G>
>
>Barry

On Sat, 10 Jul 2004 21:49:25 GMT, "U-CDK_CHARLES\\Charles" <"Charles
Krug"@cdksystems.com> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

Another use for the shop cat?

>You need to line the box with at least an inch of something fluffy. A
>roll of 3-1/2" fibreglass is, again, probably Good Enough.

On Sun, 11 Jul 2004 08:02:45 +0800, Old Nick <[email protected]>
wrote:
> On Sat, 10 Jul 2004 21:49:25 GMT, "U-CDK_CHARLES\\Charles" <"Charles
> Krug"@cdksystems.com> vaguely proposed a theory
> ......and in reply I say!:
>
> remove ns from my header address to reply via email
>
> Another use for the shop cat?
>
>>You need to line the box with at least an inch of something fluffy. A
>>roll of 3-1/2" fibreglass is, again, probably Good Enough.
>

Too dense to kill the reflections. Keep the cat though. Mice just LOVE
the glue on certain brands of cone surrounds. Cat food is cheaper than
speaker reconing.

On Tue, 13 Jul 2004 11:01:52 GMT, B a r r y
<[email protected]> vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email


>Depends on the speaker. Some are designed for sealed boxes, some for
>ported. Check the specs.

OK. Thought it over. I had always assumed that the reccommended box
was to do with sound characteristics, not the ddanger of blowing
cones. This has always been born out for me by the fact that some
speakers just sound like shit in a vented/closed etc enclosure.
>
>I've also seen speakers blown the way you describe, but it had nothing
>to do with the box. A subsonic noise component drove them right out
>of the baskets. <G>

Popping the cone...no that has another meaning altogether, IIRC.

It would have _something to do with the box, surely. The back-pressure
in a sealed enclosure _may_ have saved that one time.

I do remember that stage speakers have a completely different
magnet/coil setup, so that the coil moves out of the magnetic field
before the coil pops out of the basket.

"U-CDK_CHARLES\Charles" <"Charles Krug"@cdksystems.com> wrote in message
news:[email protected]...
> On Sat, 10 Jul 2004 19:53:13 GMT, Edwin Pawlowski <[email protected]> wrote:
> > I'm building a speaker box at the request of my grandson. With
information
> > from a thread long ago and excellent information supplied by Dean Reece,
I'm
> > somewhat prepared to start. I'm not prepared to listen to them once
> > installed, but that is a whole 'nuther story.
> >
> > Speakers are Infinity 12.1 12" woofers. Box will be 3/4" MDF lined
with
> > fiberfill. I have a sketch from Nathan that shows an angled front,
about
> > 16" high, 16" deep at the base, 12" deep at the top. It is 36" long. It
will
> > be a sealed box with no port.
> >
>
> DAGS for "winISD." Download and install the "beta" version.
>
> Get the "Theile/Small" parameters from the manufacturers website if it's
> not already in the database.
>
> That program has TONS of information about how to make the box.
>
> For materials, High Density Fibreboard is often recommended by
> driver manufacturers, but of course it can't get wet. Void-free birch
> ply is probably Good Enough.
>
> You need to line the box with at least an inch of something fluffy. A
> roll of 3-1/2" fibreglass is, again, probably Good Enough.
>

There are some really good books out there that cover speaker
enclosures, the library is bound (no pun intended) to have one.

The book I eventually purchased is called "Speakers for your Home and
Automobile" by Gordon McComb, Alvis J. Evans, and Eric J. Evans.

Don't forget air ports. Subwoofers need a lot of air, and they can be
damaged by the pressure difference between inside and outside at higher
volumes. (Don't ask me how I know)

Also, rather than fiberfill inside, I have found that carpet scraps work
wonderfully and are almost free. And probably easier to use than the cat.

On Sat, 10 Jul 2004 15:15:08 -0500, "Swingman" <[email protected]> wrote:

>
>"Edwin Pawlowski" wrote in message
>
>> OK, now for the questions. The front I plan to make a straight vertical
>> strip about 2" high and then set the face at about 15 degrees. Any reason
>> not to? Speakers will be mounted side by side.
>>
>> I'm planning to use biscuits and glue it together.
>
>Personally, I would use rabbet joints, glue and screws on speaker boxes ...
>most of the top end speakers are made this way.

Would lock miters be as strong here? Any benefit? I'm just not sure
of the usefulness of screws in MDF. If the glue joint fails it seems
the screws would give loose too.

JP

> Should I make one of the
>> panels in two pieces, leaving a section unglued for access to wires? I'd
>> just screw it in place and use some sort of gasket material.

I am not going to answer your question because I don't know. But I suggest
you advise your grand son to insulation behind the rear license plate,
between the deck lid and its reinforcement bars, under the package shelf,
between any metal surfaces that are within 1/4" of each other, and attached
insulation to any panel that can be flexed by 100 pounds of force.

Normally a car with these type speakers can be heard half a block away
because of all the ratteling sheet metal.

Well maybe my suggestions would take all the fun out of having a car that
shakes, rattles, and rolls when the radio is on. :~) Savor the time you
spend with your grandson. I hope to have one in about 10 to 15 years.

"Old Nick" wrote in message

> >Don't forget air ports. Subwoofers need a lot of air, and they can be
> >damaged by the pressure difference between inside and outside at higher
> >volumes. (Don't ask me how I know)
>
> Can you describe that? Serious. I have seen speakers blown by too
> _little_ back pressure (over excursion) caused by ducts.
>
> What happened?

Driver design ... some drivers are designed to be ported, others not. There
is a good deal of magic/art in correct porting of a specific driver for a
certain sound and the size of the box, despite the physics involved and the
manufacturer's recommendations. I used to build my bass cabinets based on
the old Dietz design, which was a favorite for bass players in the "old
days" and I experimented with many different porting sizes and designs on
most of them ... AAMOF, I still play through an old Altec 15" bass speaker
in an original Dietz box that I customized the porting on..

--
www.e-woodshop.net
Last update: 7/10/04

"Elwood Dowd" <[email protected]> wrote in message
>
> The book I eventually purchased is called "Speakers for your Home and
> Automobile" by Gordon McComb, Alvis J. Evans, and Eric J. Evans.
>
> Don't forget air ports. Subwoofers need a lot of air, and they can be
> damaged by the pressure difference between inside and outside at higher
> volumes. (Don't ask me how I know)
>
> Also, rather than fiberfill inside, I have found that carpet scraps work
> wonderfully and are almost free. And probably easier to use than the cat.

I'll have to look it up if I make another. This has been interesting once I
got into it a bit. Lots more to it than meets the eye first time out.
Ed