does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to make
a rectangular box with the subwoofer mounted in the front.

The shape doesn't matter, only the volume.


Paul Vina




"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

The shape doesn't matter, only the volume.


Paul Vina




"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

thanks paul

"Paul Vina" wrote in message
news:UzLZb.94185$jk2.443332@attbi_s53...
The shape doesn't matter, only the volume.


Paul Vina




"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

Round is the best shape, square is the worst. You do not want any parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

Round is the best shape, square is the worst. You do not want any parallel
walls in your box because of standing waves.

Huh?

You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

why you say I am nuts?


"Kevin McMurtrie" wrote in message
...
You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume
matters.

I want to make a box with a variable volume and the best way is then
to
make
a rectangular box with the subwoofer mounted in the front.

pil wrote:
does it matter what shape you use? I heard that only the volume matters.

Shape does not matter what-so-ever.

I want to make a box with a variable volume and the best way is then to make
a rectangular box with the subwoofer mounted in the front.

You could concievably build a tube, using cardboard casting tubes. These
are used by construction companies when casting concrete pylons on-site.

If you only need to make slight variations in volume (likely), then you
can accomplish this with any solid object - just toss a brick or a block
of wood in. Anything that displaces volume will lower the internal
volume of your box when you throw it in.


--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
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"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

I suggest you guys do some research.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what the
wedges are on all the walls for.


"Kevin McMurtrie" wrote in message
...
You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume
matters.

I want to make a box with a variable volume and the best way is then
to
make
a rectangular box with the subwoofer mounted in the front.

Shape is not that important. If you can build an egg shaped enclousur
that would be best, avoid perfect cubes. OTOH if you look at how man
high end speaker manufactures have paralell walls, I don't think tha
is huge deal if you build the enclosure properly.

As for adjustable volume what I've found that works great is I get
bunch of 1 liter water bottles, fill them 1/3 to 1/2 way wit
insulating expanding foam. After the foam cures I cut away the plasti
and have a bunch of .035cuft foam cylinders. I throw these in th
enclosure and then I can get an idea of the actual box volume fo
future reference
-
Jimi7
-----------------------------------------------------------------------
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"Jimi77" wrote in message
s.com...
Shape is not that important. If you can build an egg shaped enclousure
that would be best, avoid perfect cubes. OTOH if you look at how many
high end speaker manufactures have paralell walls, I don't think that
is huge deal if you build the enclosure properly.

They might LOOK parallel from the outside, but on the inside you'll notice
that there are mesures taken to insure that there are no parallel surfaces.
We normally split some PVC pipe in half lenghways and mount them on the
surfaces inside the box (like inverted half pipes). This takes up very
little volume and eliminates all standing waves. Just a little something I
picked up from Richard Clark.

Once again, there's no room for a standing wave between the walls of a
sub enclosure. Not unless the sub's VAS is in the tripple digits.


In article . net,
"Pug Fugley" wrote:

I suggest you guys do some research.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what the
wedges are on all the walls for.


"Kevin McMurtrie" wrote in message
...
You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume
matters.

I want to make a box with a variable volume and the best way is then
to
make
a rectangular box with the subwoofer mounted in the front.

"Kevin McMurtrie" wrote in message
...
Once again, there's no room for a standing wave between the walls of a
sub enclosure. Not unless the sub's VAS is in the tripple digits.

Okay. Every speaker manufacturer on the planet disagrees, but okay.

Kevin McMurtrie wrote:


Once again, there's no room for a standing wave between the walls of a
sub enclosure. Not unless the sub's VAS is in the tripple digits.

This is true but not because of Vas. Standing waves can form between any two
opposing walls as a function of the wavelength of the sound being produced. At
subwoofer frequencies the wavelengths are very long; much longer then the 1/4
wavelength required for a standing wave to form. For a cabinet with a 16-inch
longest dimension internal standing wave patterns will begin forming at about
400 Hz and upward.

At lower frequencies the enclosure becomes a pressue pot and speaker
displacement simply pressurizes the entire enclosure evenly.

The interior of your listening room (or car) works in the same way at low
frequencies and provides 12 dB of bass reinforcement as frequency falls. (low
frequency cabin gain.) This is why you can get so much more bass your car than
in your living room. The smaller the space the easier to pressurize it. This is
why you can actually hear bass with sealed back headphones.

Now it's also not well known that non-parallel walls do not eliminate standing
waves.... they only make it more difficult to predict their frequency in
advance.


In article . net,
"Pug Fugley" wrote:

I suggest you guys do some research.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what the
wedges are on all the walls for.

The wedges are to provide more absorption surface area. The dimensions of the
space itself dtermine the standing wave patterns. The wedges have nothing to do
with it.

"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.

Again internal standing waves are a middle-high frequency function. But what
shape do reverberation chambers have? You guessed it .....globe. Why because
that shape keeps the sound going longer because of the shape. Olsen suggested
than a sphere has the lowest external diffraction of any shape but that has
nothing to do with internal standing waves.

Never build a box out of wood. Use MDF (medium density fiberboard) or
countertop quality particle board (high density). Every sub made comes with
a document revealing the Thiel Small Parameters of that driver.Go to the
brand's web site and find enclosure plans. While the shape doesn't matter
for an ordinary sealed box as long as the interior volume is satisfied, more
complex enclosures like bandpass, or ported, require more consideration.
Some guys want to hear the bass accurately, insde their car. Since they
don't sit in the trunk, it's a waste to pump all that bass into that space.
A box designed with a partially external port exiting from the top of a box
could pass through an opening in the rear package shelf and deliver "tight"
bass INSIDE the car! P.







"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

Pug Fugley wrote:
* They might LOOK parallel from the outside, but on the inside
you'll notice that there are mesures taken to insure that there are
no parallel surfaces. We normally split some PVC pipe in half
lenghways and mount them on the surfaces inside the box (like
inverted half pipes). This takes up very little volume and eliminates
all standing waves. Just a little something I
picked up from Richard Clark. *

Huh? I repaired high end speakers for years, 90%+ of them had
perfectly paralell walls. They all however were well damped, which
does just fine killing any "standing waves" resonance, etc.
--
Jimi77
------------------------------------------------------------------------
CarAudioForum.com - Usenet Gateway w/over one million posts online!
View this thread: http://www.caraudioforum.com/showthr...hreadid=177551

"Jimi77" wrote in message
s.com...
Pug Fugley wrote:
* They might LOOK parallel from the outside, but on the inside
you'll notice that there are mesures taken to insure that there are
no parallel surfaces. We normally split some PVC pipe in half
lenghways and mount them on the surfaces inside the box (like
inverted half pipes). This takes up very little volume and eliminates
all standing waves. Just a little something I
picked up from Richard Clark. *

Huh? I repaired high end speakers for years, 90%+ of them had
perfectly paralell walls. They all however were well damped, which
does just fine killing any "standing waves" resonance, etc.

They must not have been THAT high end. Cerwin Vega does not count.

Actually those "wedges" are acoustic foam that absorb reflections. They
don't have anything to do with standing waves.


Paul Vina






"Pug Fugley" wrote in message
ink.net...
I suggest you guys do some research.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what
the
wedges are on all the walls for.


"Kevin McMurtrie" wrote in message
...
You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume
matters.

I want to make a box with a variable volume and the best way is then
to
make
a rectangular box with the subwoofer mounted in the front.

"Peter Klein" wrote:

Never build a box out of wood.

The problem with solid wood is that it changes dimension with temperature amd
humidity. This can cause warps, splitting or leaks

Use MDF (medium density fiberboard) or
countertop quality particle board (high density).

Plywood is also quite good but may require more bracing.

Every sub made comes with
a document revealing the Thiel Small Parameters of that driver.Go to the
brand's web site and find enclosure plans. While the shape doesn't matter
for an ordinary sealed box as long as the interior volume is satisfied, more
complex enclosures like bandpass, or ported, require more consideration.
Some guys want to hear the bass accurately, insde their car. Since they
don't sit in the trunk, it's a waste to pump all that bass into that space.
A box designed with a partially external port exiting from the top of a box
could pass through an opening in the rear package shelf and deliver "tight"
bass INSIDE the car! P.

The main issues with bass reflex enclosures in the car is that they do not load
the driver below the tuned frequency of the system and will normally require a
high pass filter.

Secondly, bass reflex systems roll-off at 24 dB per octave below the tuning
frequency compared to sealed systems which roll-off at 12-dB per octave. This
means that a sealed systems gets full benefit of cabin gain (12-dB
reinforcement below the lowest axial mode in the listening space (60 Hz in
smaller cars and sometimes as low as 40 Hz in vans)) and this advantage is
foregone with bass reflex systems.

On the other hand, bass reflex systems often have a 6-10 dB boost in response
in the mid-upper bass that folks may find pleasing but it isn't quality sound.

Pug Fugley wrote:
I suggest you guys do some research.

Well thats a bold statement.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what the
wedges are on all the walls for.

There's a little difference between an acoustic chamber and a 1.5 ft^3 box.

You are clueless. You need to do some research yourself. Start on google
with the words "standing wave".


--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

Pug Fugley wrote:
Just a little something I
picked up from Richard Clark.

HA HA HA HA! THE BLIND LEADING THE CLUELESS!

Pug, you noob, Richard Clark never taught you this! Even he knows better
than to think a standing wave could form in a 1.5 ft^3 box!!!

http://www.teamrocs.com/crap/newbie.html -- For you.

--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

Pug Fugley wrote:

Okay. Every speaker manufacturer on the planet disagrees, but okay.

Show me a speaker manufacturer that advises you to avoid a square box. I
dare you.

Go ahead, I'll wait right here. Run along now.


--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

Peter Klein wrote:
Never build a box out of wood. Use MDF (medium density fiberboard) or
countertop quality particle board (high density).

Use MDF - so that the first time your box gets wet, it falls apart.
Better yet, use particle board, so that if you overtighten your screws
it rips the screw hole out.

MDF is used because a) it is cheap (62 cents per square board foot), and
b) the cellular nature of the particles of the wood fights resonances.
On the other hand, you could use 3/4" 7 ply russian birch, which also
fights resonance because the grain of the ply is set at 90 degree
angles. It's far stronger than MDF, so you don't need to double up or
brace large panels. It's also $1.56 per square board foot.

By the way, the Fiber in Medium Density Fiberboard is wood. It's finely
granulated sawdust which is bound with an epoxy under pressure.



A box designed with a partially external port exiting from the top of a box
could pass through an opening in the rear package shelf and deliver "tight"
bass INSIDE the car! P.

That's just stupid. The port delivers a narrow set of frequencies. The
driver itself (the woofer) delivers most of the frequencies. Running the
port inside the car delives a fraction of the overall output of the box,
further skewing the response of the subwoofer, and the listener also has
to hear that port turbulence.



--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
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"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

Pug Fugley wrote:

They must not have been THAT high end. Cerwin Vega does not count.

Then we'll try B&W, Mark Levinson, or other five figure priced speakers
- they all make square enclosures for their speakers too.

You're an idiot.

http://www.teamrocs.com/crap/newbie.html

--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
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"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

I like standing waves!!

Pug Fugley wrote:

Round is the best shape, square is the worst. You do not want any parallel
walls in your box because of standing waves.

"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

Shoulda wore a condom!!

Pug Fugley wrote:

. Just a little something I
picked up from Richard Clark.

a typicl sub box, crossed over like most of us do, will be too small to
have any significant standing waves in it at the subs frequencies....

I SUGGEST YOU DO SOME RESEARCH!!!

Smartypants..!! Tell me this if your such a Clarkie .. er, I mean EXPERT...

Tell me the minimum distance from a reflector for a sound to bounce back
and cause a first cancelation... (thats what standing waves do) Now the
minimum
distance for the first reinforcment to occur...???

You gonna run over to RICHARD CLARKS forum and ask...??
Or are you gonna figgure this one out by yourself..??

Eddie Runner

Pug Fugley wrote:

I suggest you guys do some research.

A perfect square is the WORST shape you can have for a speaker enclosure.
You ever seen an acoustic chamber with flat walls? Hell no. That's what the
wedges are on all the walls for.

"Kevin McMurtrie" wrote in message
...
You're nuts, of course. The resonance frequency of a sub is that of the
entire box acting as a whole. There's no room for standing waves.
Wide-range speakers could get standing waves (echoes) and that's why
they're stuffed with acoustic insulation to prevent it.

The only downside to flat surfaces is that they aren't as strong as
other shapes. It's easily solved by gluing on cross beams.


In article . net,
"Pug Fugley" wrote:

Round is the best shape, square is the worst. You do not want any
parallel
walls in your box because of standing waves.



"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume
matters.

I want to make a box with a variable volume and the best way is then
to
make
a rectangular box with the subwoofer mounted in the front.

standing waves ARE reflections Paul... ;-)

Paul Vina wrote:

Actually those "wedges" are acoustic foam that absorb reflections. They
don't have anything to do with standing waves.

Paul Vina

Liz,...

On the contrary,
most books on speaker design do suggest a rectangular box
is better than a square box and a strange sized box is even better
than that.. And like the guy said early on, a round box would even be
better than that in this respect..

Actually, come to think of it, I think the round box was better not less
internal reflections but for less fron baffle f\reflections into the listening
area... Nix that bout the round box... I dont agree with what he said..

But, these box design texts are generally talking about a HOME box that
might have more of a full range in em... NOT a car sub box which just
plays low frequencies... So his reasoning is invalid...

But if he took a mind to, he could product dozens of speaker texts that
say dont build a square box...

Just be carefull you dont confuse yourself...!!

ha ha ha

Eddie Runner

thelizman wrote:

Shape does not matter what-so-ever.

I LIKE WOOD!!
There are plenty of woods you can use... MDF isnt best!

Peter Klein wrote:

Never build a box out of wood. Use MDF (medium density fiberboard) or
countertop quality particle board (high density). Every sub made comes with
a document revealing the Thiel Small Parameters of that driver.Go to the
brand's web site and find enclosure plans. While the shape doesn't matter
for an ordinary sealed box as long as the interior volume is satisfied, more
complex enclosures like bandpass, or ported, require more consideration.
Some guys want to hear the bass accurately, insde their car. Since they
don't sit in the trunk, it's a waste to pump all that bass into that space.
A box designed with a partially external port exiting from the top of a box
could pass through an opening in the rear package shelf and deliver "tight"
bass INSIDE the car! P.

"pil" wrote in message
...
does it matter what shape you use? I heard that only the volume matters.

I want to make a box with a variable volume and the best way is then to
make
a rectangular box with the subwoofer mounted in the front.

SHAPE: Square and Round are bad, as far as standing waves go. Odd
proportions are best. i.e. L=X, W=1.3X, H=1.7X Yes, egg-shapped is
IDEAL for many reasons. Also, you can fill the bottom with sand and
it just keeps coming back for more!

FOR SUBS ONLY: It is true that if greatest dimension is 16" , then
no chance of standing waves below 200 Hz (not 400 Hz as was previously
stated here, because a full wavelenth of sound at 200 Hz is 68 inches,
and 1/4 of that is about 16".) Also, standing waves can, if fact,
occur at very low frequencies. i.e. As proof, some pipe organs go
down to 20 Hz, or even lower.

CAR DOOR CAVITY STANDING WAVES: Any "rectangular" cavity/enclosure
will have 3 fundamental resonant (aka standing wave) frequencies, each
corresponding to L, W, H dimensions. A typical car door cavity
approximates a rectangular box shape with dimensions approximately:
36" x 24" x 6". The corresponding fundamental frequencies are,
rspectively: 188Hz, 283Hz, and 1130Hz. (These values correspond to a
node at each opposing door cavity surface. i.e. one half of a
wavelength, aka "one full jumprope".) One quarter wavelength values
are also possible to occur, as the speaker cone itself would act as
the "open end" at the midpoint of the "jumprope".

I still think that lining the inide of the door cabity with bubble
wrap would be beneficial.

Check this out!

http://www.mcsquared.com/wavelength.htm

The menu on the left side leads to some very interesting sound bits!

Eddie Runner wrote:

I LIKE WOOD!!

we'll just put that in the archive...
--
sancho
bout time ed 'came out'

Yes an egg or whatever oddball shape you can come up with works best.
But obviously the gains are minimal enough that very few high en
manufactures pursue the benefits of non-rectangular enclosure
-
Jimi7
-----------------------------------------------------------------------
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Jimi77 wrote:
Yes an egg or whatever oddball shape you can come up with works best.
But obviously the gains are minimal enough that very few high end
manufactures pursue the benefits of non-rectangular enclosure.

Quote. QUOTE QUOTE QUOTE QUOTE! Do you fuggers need me to draw a picture?


--
thelizman "I didn't steal the FAQ either"

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
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"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

no no no...

MY WOOD!!
not your wood you HOMO!

sancho wrote:

Eddie Runner wrote:

I LIKE WOOD!!

we'll just put that in the archive...
--
sancho
bout time ed 'came out'

Eddie Runner wrote:

no no no...

MY WOOD!!
not your wood you HOMO!

you should have specified...
--
sancho
this post was intended for usenet, if you are reading this post on a
webforum it is because someone has STOLEN it to use as content to draw
traffic to his site... please acquire a proper newsreader if you want to
access rec.audio.car and rethink your patronage of said site...