speaker box assignment

[[email protected]]

I'm studying industrial design at Wentworth Institute of Technology
in Boston. I have been given the following assignment: to design a
speaker enclosure to house a 4" woofer and a 2" diameter tweeter.
The tweeter is an Onkyo 3/8" (269-708) standard one-way driver.
The driver parameters are as follows:
Fs=4200 Hz
P-diameter = 0.375"
Sd=0.713sq.cm
Re=3.5 Ohms
Le-= 0.013Mh
Z=4 Ohms
Pe=20 watts
no=0.306%
1-W SPL=87dB
2.83-V SPL=90.59dB.

Woofer properties:
Goldwood, GS204/4S (290-370) standard one-way driver.
Driver parameters:
Fs = 138 Hz
Qms = 7.19
Vas= 0.991 Liters

Cms= 0.336 mm/N
Mms= 3.964 g
Rms= 0.478 kg/s
Xmax= 1.5mm
Xmech= 2.25mm
P-dia= 3in
Sd= 45.6 sq.cm
P-Vd= 0.00684 Liters
Qes= 2.2
Re= 3.333 Ohms
Le= 0.184 mH
Z= 4 ohms
BL= 2.282 N/A
Pe= 40 watts
Qts= 1.69
No= 0.114%
1-W SPL = 82.72 dB
2.83-V Spl = 86 dB

Box parameters:
Type" Closed Box
Vb= 4.248 Liters
QL=20
Fill = Heavy

My assignment is to design two bookshelf / desktop speakers that not
only produce quality sound but are visually appealing. Our professor
suggests we use ½" or ¾" MDF fiber board because it is dense and
good for sound applications. We are allowed to explore other materials
if we desire. This assignment is pretty open as far as materials and
box design. I'm not asking for someone to do all the work for me
with this assignment but rather provide me with some tips or possible
places I can find some information about speaker boxes. Anything you
can provide me would be most appreciated. Thanks!

Jesse Stein

If this is not the correct newsgroup to post this to if someone could
direct me to a more appropriate group I would really appreciate it.

 

[Fx]

http://home.earthlink.net/~etunstal/diy.htm






I'm studying industrial design at Wentworth Institute of Technology
in Boston. I have been given the following assignment: to design a
speaker enclosure to house a 4" woofer and a 2" diameter tweeter.
The tweeter is an Onkyo 3/8" (269-708) standard one-way driver.
The driver parameters are as follows:
Fs=4200 Hz
P-diameter = 0.375"
Sd=0.713sq.cm
Re=3.5 Ohms
Le-= 0.013Mh
Z=4 Ohms
Pe=20 watts
no=0.306%
1-W SPL=87dB
2.83-V SPL=90.59dB.

Woofer properties:
Goldwood, GS204/4S (290-370) standard one-way driver.
Driver parameters:
Fs = 138 Hz
Qms = 7.19
Vas= 0.991 Liters

Cms= 0.336 mm/N
Mms= 3.964 g
Rms= 0.478 kg/s
Xmax= 1.5mm
Xmech= 2.25mm
P-dia= 3in
Sd= 45.6 sq.cm
P-Vd= 0.00684 Liters
Qes= 2.2
Re= 3.333 Ohms
Le= 0.184 mH
Z= 4 ohms
BL= 2.282 N/A
Pe= 40 watts
Qts= 1.69
No= 0.114%
1-W SPL = 82.72 dB
2.83-V Spl = 86 dB

Box parameters:
Type" Closed Box
Vb= 4.248 Liters
QL=20
Fill = Heavy

My assignment is to design two bookshelf / desktop speakers that not
only produce quality sound but are visually appealing. Our professor
suggests we use ½" or ¾" MDF fiber board because it is dense and
good for sound applications. We are allowed to explore other materials
if we desire. This assignment is pretty open as far as materials and
box design. I'm not asking for someone to do all the work for me
with this assignment but rather provide me with some tips or possible
places I can find some information about speaker boxes. Anything you
can provide me would be most appreciated. Thanks!

Jesse Stein

If this is not the correct newsgroup to post this to if someone could
direct me to a more appropriate group I would really appreciate it.

 

[none]

I'm studying industrial design at Wentworth Institute of Technology
in Boston. I have been given the following assignment: to design a
speaker enclosure to house a 4" woofer and a 2" diameter tweeter.
The tweeter is an Onkyo 3/8" (269-708) standard one-way driver.
The driver parameters are as follows:
Fs=4200 Hz
P-diameter = 0.375"
Sd=0.713sq.cm
Re=3.5 Ohms
Le-= 0.013Mh
Z=4 Ohms
Pe=20 watts
no=0.306%
1-W SPL=87dB
2.83-V SPL=90.59dB.

Woofer properties:
Goldwood, GS204/4S (290-370) standard one-way driver.
Driver parameters:
Fs = 138 Hz
Qms = 7.19
Vas= 0.991 Liters

Cms= 0.336 mm/N
Mms= 3.964 g
Rms= 0.478 kg/s
Xmax= 1.5mm
Xmech= 2.25mm
P-dia= 3in
Sd= 45.6 sq.cm
P-Vd= 0.00684 Liters
Qes= 2.2
Re= 3.333 Ohms
Le= 0.184 mH
Z= 4 ohms
BL= 2.282 N/A
Pe= 40 watts
Qts= 1.69
No= 0.114%
1-W SPL = 82.72 dB
2.83-V Spl = 86 dB

Box parameters:
Type" Closed Box
Vb= 4.248 Liters
QL=20
Fill = Heavy

My assignment is to design two bookshelf / desktop speakers that not
only produce quality sound but are visually appealing. Our professor
suggests we use ½" or ¾" MDF fiber board because it is dense and
good for sound applications. We are allowed to explore other materials
if we desire. This assignment is pretty open as far as materials and
box design. I'm not asking for someone to do all the work for me
with this assignment but rather provide me with some tips or possible
places I can find some information about speaker boxes. Anything you
can provide me would be most appreciated. Thanks!

Jesse Stein

If this is not the correct newsgroup to post this to if someone could
direct me to a more appropriate group I would really appreciate it.

Try the following links.

http://www.speakermania.com/
http://www.madisound.com/cgi-bin/discuss.cgi?
http://www.diysubwoofers.org/talkshop/
http://f16.parsimony.net/forum27133/index.htm
http://www.pesupport.com/cgi-bin/config.pl
http://www.spiceisle.com/audiodiy/
http://www.diyaudio.com/
http://www.speakerbuilding.com/
http://www.us-epanorama.net/audiospeakers.html
http://www.hi-fi.com/speaker/
http://www.sound.au.com/tsp.htm
http://www.geocities.com/SiliconValley/Park/1187/speakernet.html
http://www.melhuish.org/audio/links.htm
http://www.scrounge.org/speak/speak.htm
http://www.globalnode.com/users/stevenr/xover3.htm
http://www.audioasylum.com/audio/speakers/bbs.html
http://members.tripod.com/XSSpl/Audio/Sound.htm
http://www.speakerworks.net/
http://www.madisound.com/
http://www.speakercity.com/
http://www.epanorama.net/measuring.html
http://www.epanorama.net/measuring.html#audio
http://www.trueaudio.com/linksp1.htm
http://www.audioholics.com/Message_Forums.htm
http://www.i-depth.com:80/P/k/kj05019.frm.speakmess.html
http://www.AudioAsylum.com/audio/speakers/bbs.html


Some of these links are old but their should be something there
that'll get you started.

I've used a program called win ISD to calculate box volumes and dimns
that is fairly accurate and is free to be had at their site.

www.linearteam.org/winisd.html

There are better programs but this one gets the job done.

If your going with a woofer as small as 4 inchs 1/2 inch mdf will do
though I always use 3/4 or thicker for my projects.
The key thing for getting good sound out of such a small driver is to
be sure to limit the low pass frequencies to keep response tight.( I
wouldn't try and drive anything below 40hz into it, it would most
likely cause distortion and will certainly rob it of most of it's
efficiency.)
Keep the design simple, go with a sealed box, you really won't see
much benefit from porting with such a small driver.( You might
consider a dual woofer setup wired out of phase if you can get two
more of those Goldwood's.(It's called an isobarik or push/pull design
and works wonders when used with smaller drivers. Most designs use a
simple tube configuration which can be designed for an esthetically
pleasing appearance.)


Here are a couple of up-to-date links for software.

http://melhuish.org/audio/software.html

http://www.audiogrid.com/audio/

 

[GregS]

I'm studying industrial design at Wentworth Institute of Technology
in Boston. I have been given the following assignment: to design a
speaker enclosure to house a 4" woofer and a 2" diameter tweeter.
The tweeter is an Onkyo 3/8" (269-708) standard one-way driver.
The driver parameters are as follows:
Fs=3D4200 Hz
P-diameter =3D 0.375"
Sd=3D0.713sq.cm
Re=3D3.5 Ohms
Le-=3D 0.013Mh
Z=3D4 Ohms
Pe=3D20 watts
no=3D0.306%
1-W SPL=3D87dB
2=2E83-V SPL=3D90.59dB.

Woofer properties:
Goldwood, GS204/4S (290-370) standard one-way driver.
Driver parameters:
Fs =3D 138 Hz
Qms =3D 7.19
Vas=3D 0.991 Liters

Cms=3D 0.336 mm/N
Mms=3D 3.964 g
Rms=3D 0.478 kg/s
Xmax=3D 1.5mm
Xmech=3D 2.25mm
P-dia=3D 3in
Sd=3D 45.6 sq.cm
P-Vd=3D 0.00684 Liters
Qes=3D 2.2
Re=3D 3.333 Ohms
Le=3D 0.184 mH
Z=3D 4 ohms
BL=3D 2.282 N/A
Pe=3D 40 watts
Qts=3D 1.69
No=3D 0.114%
1-W SPL =3D 82.72 dB
2=2E83-V Spl =3D 86 dB

Box parameters:
Type" Closed Box
Vb=3D 4.248 Liters
QL=3D20
Fill =3D Heavy

My assignment is to design two bookshelf / desktop speakers that not
only produce quality sound but are visually appealing. Our professor
suggests we use =BD" or =BE" MDF fiber board because it is dense and
good for sound applications. We are allowed to explore other materials
if we desire. This assignment is pretty open as far as materials and
box design. I'm not asking for someone to do all the work for me
with this assignment but rather provide me with some tips or possible
places I can find some information about speaker boxes. Anything you
can provide me would be most appreciated. Thanks!

Jesse Stein

If this is not the correct newsgroup to post this to if someone could
direct me to a more appropriate group I would really appreciate it.

The so called woofer is a bit strange. It high resonance is higher than typical full
range drivers, and it sensitivity is very low. Both strange. Your going to be using
a high crossover frequency, so stuffing requirments are not only for bass response,
but also high frequency attenuation. I would use foam and or fiberglass since
they have the best attenuation.

greg

 

[JW]

We are allowed to explore other materials
if we desire. This assignment is pretty open as far as materials and
box design.

I'd always figured that granite enclosures would rule audio-wise - they'd
look nice too. All other things being equal, I suspect that the higher the
density of the enclosure material, the better the sound quality.

 

[jakdedert]

I'd always figured that granite enclosures would rule audio-wise - they'd
look nice too. All other things being equal, I suspect that the higher the
density of the enclosure material, the better the sound quality.

I just salvaged almost 3000 solid bricks from a house scheduled for
demolition. I wonder what kind of enclosure 'those' would make.....?

jak

 

[Kalman Rubinson]

I'd always figured that granite enclosures would rule audio-wise - they'd
look nice too. All other things being equal, I suspect that the higher the
density of the enclosure material, the better the sound quality.

Mebbe but it's not so much the density as the damping. Some of the
best enclosures were made of Aerolam damped with bituminous felt.
Many modern enclosures are made of synthetic laminates with internal
damping layers.

One might check the archives of speaker reviews at www.stereophile.com
(shameless plug) to see the bench tests of speaker enclosure
resonances. Fewer and shorter is better.

Kal

 

[JW]

Mebbe but it's not so much the density as the damping.

Correct me if I'm wrong, but wouldn't a higher density material cause the
damping to improve? (Lead speakers anyone?)

 

[Kalman Rubinson]

Correct me if I'm wrong, but wouldn't a higher density material cause the
damping to improve? (Lead speakers anyone?)

Lead is dense and soft, both of which contribute to its damping
properties. The problem with simply saying that a dense material is
sufficient is that it leaves out the thickness. A dense but thin wall
is harder to damp than a light but thin wall. Same for thick walls.
It really depends on the sizes of the walls and where you want to move
the resonances.

As a general rule, you can get away with dense, thick, braced panels
but that might not be practical (or moveable).

Kal

 

[Mike W.]

4+ liters sounds big for a 4" woofer to me. Particle board or plywood (high
grade, very fer voids) are good choices.

 

[Michael Kennedy]

Correct me if I'm wrong, but wouldn't a higher density material cause the
damping to improve? (Lead speakers anyone?)

or depleted uranium : )

 

[JW]

or depleted uranium : )

Two birds with one stone! Who could ask for anything more?

 

[none]

or depleted uranium : )

I'm not sure exactly what you mean by dampening but will have a go at
explaining why dampening materials are of benefit in box building.
In regards to dampening in box material itself( mdf, plywood, concrete
etc...) Yes the more rigid and dense the material the better as it
acts to reflect the back waves better resulting is less energy loss
and of course lower resonance which only adds coloration/noise.
In box stuffing the idea is to add a material such as polyfill which
acts as an "acoustic maze" or baffle which has the effect of
increasing box volume. There are special materials such as
acoustastuff which has the optimum characteristics, they can be had at
parts express or any good speaker parts dealer.
In the old days we used a material called kimsul, a kind of wool-like
material which has been rendered obsolete by better materials

As for box materials, I've seen them made with just about every kind
of high density material.
I've always favored acoustic plywood.( 10 ply birch or white oak,
usually 1-1/4 inch thick. It has the advantage of being a bit denser
than regular plywood as it's pressed under greater pressure and with a
glue that has stronger adhesion qualities than the water based stuff
used in ordinary ply.)
The best box I've seen in regards to it's dampening properties was
formed out of concrete. Hard to build, heavy as hell and not too
attactive in the home setting though.
Years back a friend of mine had me help him wire up an isobarik that
he'd made using 8 inch concrete drain pipe. About 4 feet tall as I
recall using two woofers wired out of phase for push/pull effect.
The bass was fairly clean and it had decent efficiency specs but were
they heavy! Not too pretty either.(though he did improve their looks
with some concrete paint and a bit of gloss laquer.)

I've had occasion to use the mdf especially designed for audio
boxes.(can be gotten at most automotive sound shops)
It's of a finer construct material and is sealed on the outer surfaces
rather than the more coarse, open grain stuff you get at home building
supply stores. It's also thicker( 7/8 for what we used) and is easier
to apply paints or finishing coats to.

I talked to a fellow online that was attempting to use wonderboard to
build a set of boxes, though I never heard how it worked out.

 

[Asimov]

"none" bravely wrote to "All" (05 Nov 05 04:49:02)
--- on the heady topic of "Re: speaker box assignment"

no> From: none <[email protected]>
no> Xref: core-easynews sci.electronics.repair:347606

no> On Thu, 3 Nov 2005 01:58:39 -0500, "Michael Kennedy"

or depleted uranium : )

no> I'm not sure exactly what you mean by dampening but will have a go at
no> explaining why dampening materials are of benefit in box building.
no> In regards to dampening in box material itself( mdf, plywood, concrete
no> etc...) Yes the more rigid and dense the material the better as it
no> acts to reflect the back waves better resulting is less energy loss
no> and of course lower resonance which only adds coloration/noise.
no> In box stuffing the idea is to add a material such as polyfill which
no> acts as an "acoustic maze" or baffle which has the effect of
no> increasing box volume. There are special materials such as
no> acoustastuff which has the optimum characteristics, they can be had at
no> parts express or any good speaker parts dealer.
no> In the old days we used a material called kimsul, a kind of wool-like
no> material which has been rendered obsolete by better materials

no> As for box materials, I've seen them made with just about every kind
no> of high density material.
no> I've always favored acoustic plywood.( 10 ply birch or white oak,
no> usually 1-1/4 inch thick. It has the advantage of being a bit denser
no> than regular plywood as it's pressed under greater pressure and with a
no> glue that has stronger adhesion qualities than the water based stuff
no> used in ordinary ply.)
no> The best box I've seen in regards to it's dampening properties was
no> formed out of concrete. Hard to build, heavy as hell and not too
no> attactive in the home setting though.
no> Years back a friend of mine had me help him wire up an isobarik that
no> he'd made using 8 inch concrete drain pipe. About 4 feet tall as I
no> recall using two woofers wired out of phase for push/pull effect.
no> The bass was fairly clean and it had decent efficiency specs but were
no> they heavy! Not too pretty either.(though he did improve their looks
no> with some concrete paint and a bit of gloss laquer.)

no> I've had occasion to use the mdf especially designed for audio
no> boxes.(can be gotten at most automotive sound shops)
no> It's of a finer construct material and is sealed on the outer surfaces
no> rather than the more coarse, open grain stuff you get at home building
no> supply stores. It's also thicker( 7/8 for what we used) and is easier
no> to apply paints or finishing coats to.

no> I talked to a fellow online that was attempting to use wonderboard to
no> build a set of boxes, though I never heard how it worked out.


Speaking of experimenting, how about making an enclosure out of a
semi-rigid shell perhaps 1/4" thick (aluminium alloy?) but lined on
the inside with sonopan glued to its inner surface? It would lose some
efficiency but it could then be much lighter weight. I've seen a
similar sandwich construction used in quieting ventilation baffles for
mainframe computers so it isn't a new idea.

A*s*i*m*o*v

.... A stereo system is the altar to the god of music.

 

[Kalman Rubinson]

Speaking of experimenting, how about making an enclosure out of a
semi-rigid shell perhaps 1/4" thick (aluminium alloy?) but lined on
the inside with sonopan glued to its inner surface? It would lose some
efficiency but it could then be much lighter weight. I've seen a
similar sandwich construction used in quieting ventilation baffles for
mainframe computers so it isn't a new idea.

That's similar to Aerolam/bitumen idea except that the Aerolam is
lighter but stiffer for any given thickness and its lightness makes
the damping layer work more effectively.

Kal