A brief discussion on resolving systems with a gentleman who makes
single driver speakers in what appears to be a folded Voigt Pipe
design turned briefly to resonances. My general contention was that
since he was using alder as opposed to MDF, that it would result in
additional resonances which would color the sound. Some mild umbrage
was taken. The conversation went like this. Am I somehow missing
something here or is this a combination of spin coupled with some
factual errors regarding wood?

Him: Sure, it will resonate. So will wood, steel, micarta, MDF, and
ANYTHING ELSE that has any mechanical stiffness. How it resonates and
whether it's important depends upon its stiffness, it's internal
mechanical losses, how it's mounted and secured and how it's
mechanically loaded and acoustically excited.

Me: This should not be interpreted as the intentional use of materials
to impart resonances as opposed to MDF which has a more predictable
nature? In ways, it reminds me of the various woods that can be used
in the construction of guitars where I think MDF, apart from being
heavy, might not make for the most pleasing of sounds.

Him: No, you have interpreted incorrectly. A common misconception
though. But yes woods do flavor sound, for guitars and speakers. Part
of woods amazing quality is that it can be made to resonate more, as
in the case of a guitar or piano, but that same piano usues wood to
isolate the vibration (the case) so the most energy can be released to
the room (more music)
What solid wood does in the case of my speaker is resonate LESS. I use
solid wood for it's weight vs ridgidity, it is far more ridgid than
mdf. And contributes actually less in the form of self -resonance. In
addition we have have made this speaker from teak, oak, mdf, plywood,
pine, alder, maple and cherry. All have distinct sonic "flavors". The
solid wood particularly the maple extends bass and allows the very
absolute maximum energy transfer from driver cone to port to room
without imparting audible resonance of it's own. The mdf example
sounded muffled and lifeless. My designs pursue maximum energy
transfer from electrical to the room both from the front of the driver
and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.
One really has to integrate decisions about grain orientation,
thicknesses of wood as well as joint strength to carry this discussion
comparing materials to any logical extent as it relates to
speakerbuilding.

Me: If it's your position that cabinet augmentation is desireable,
then we stand on opposite sides. If you feel that it gives your
speaker a characteristic sound that is pleasing, I can live with that.

Him: The concept that you propose I subscribe to is incorrect, you
mis-nterpret my intention of reducing resonance through the use of
solid wood. MDf does not eliminate resonance. It reduces it
drastically, such that it also reduces musical content via energy
absorption.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced
with machinery. The square box (usually sealed or ported0 became the
de-facto method of augmenting the bass drivers own free-air resonance
(fs) or limiting it in the case of sealed enclosures. I submit this
has every thing to do with the advent of high powered solid state
amplifiers as equally as declining skills in our labor pool. MDF was
not created for eliminating resonance in speaker boxes but rather to
utilize vast stretches of inadequate lumber stocks. From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

Chu Gai wrote:

snip From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

These statements by "Him" seem silly. Ideally, the speaker cabinet
should add nothing to the sound coming from the speaker cones. "Him"
seems to be claiming that MD fiberboard absorbs so much of the speaker
output that the efficiency of the speaker system is compromised. That
sounds like BS to me.

Chu Gai wrote:

snip From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

These statements by "Him" seem silly. Ideally, the speaker cabinet
should add nothing to the sound coming from the speaker cones. "Him"
seems to be claiming that MD fiberboard absorbs so much of the speaker
output that the efficiency of the speaker system is compromised. That
sounds like BS to me.

Chu Gai wrote:

snip From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

These statements by "Him" seem silly. Ideally, the speaker cabinet
should add nothing to the sound coming from the speaker cones. "Him"
seems to be claiming that MD fiberboard absorbs so much of the speaker
output that the efficiency of the speaker system is compromised. That
sounds like BS to me.

Chu Gai wrote:

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room.

It seems like you are missing the fact that relatively efficient home
speakers are about 1% efficient. IOW, if you want to worry about the
inefficiency of your speakers, you would do well to look elsewhere than the
sound absorbed by the damping of the wood in the boxes.

Chu Gai wrote:

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room.

It seems like you are missing the fact that relatively efficient home
speakers are about 1% efficient. IOW, if you want to worry about the
inefficiency of your speakers, you would do well to look elsewhere than the
sound absorbed by the damping of the wood in the boxes.

Chu Gai wrote:

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room.

It seems like you are missing the fact that relatively efficient home
speakers are about 1% efficient. IOW, if you want to worry about the
inefficiency of your speakers, you would do well to look elsewhere than the
sound absorbed by the damping of the wood in the boxes.

(Chu Gai) wrote in message . com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced

Ah, the anthropological view. Of course.

Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

(Richard Kuschel) wrote in message ...
Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

Dang, you got me. I was thinking of a vibraphone.

Amusingly enough, my bass amplifier is in a cabinet made from 1/8 inch
steel panels. You can hear the resonance when you knock on it, but it
still sounds just fine.

For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

(Sam Byrams) wrote in message . com...
For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

Well, I can say one thing. MDF is a disaster waiting to happen with
portable speakers -- it swells up when it gets rained on. I always got
satisfactory results with homemade cabs when I used the regular 3/4
birch plywood from Home Depot, though I felt compelled to steer around
the voids.

(Sam Byrams) wrote in message . com...
For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

Well, I can say one thing. MDF is a disaster waiting to happen with
portable speakers -- it swells up when it gets rained on. I always got
satisfactory results with homemade cabs when I used the regular 3/4
birch plywood from Home Depot, though I felt compelled to steer around
the voids.

(Sam Byrams) wrote in message . com...
For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

Well, I can say one thing. MDF is a disaster waiting to happen with
portable speakers -- it swells up when it gets rained on. I always got
satisfactory results with homemade cabs when I used the regular 3/4
birch plywood from Home Depot, though I felt compelled to steer around
the voids.

For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

For whatever reason, MDF is actually not a good sounding speaker
material and cabs from multi-ply laminated wood, such as piano pin
block stock, offer many of the theoretical benefits of MDF while
providing better mechanical ruggedness, repairability, appearance and
they "seem to sound better"-no A/B/X proof, just seems to. Maybe it's
my imagination.

duPont Corian is a cool and underutilized material as well. The
Japanese use it in some of their nifty, but too heavy to
cost-effectively import, cabs for classic coax drivers such as the
Altec 604, which I consider to be the "Marilyn Monroe of speakers".

(Richard Kuschel) wrote in message ...
Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

Dang, you got me. I was thinking of a vibraphone.

Amusingly enough, my bass amplifier is in a cabinet made from 1/8 inch
steel panels. You can hear the resonance when you knock on it, but it
still sounds just fine.

(Richard Kuschel) wrote in message ...
Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

Dang, you got me. I was thinking of a vibraphone.

Amusingly enough, my bass amplifier is in a cabinet made from 1/8 inch
steel panels. You can hear the resonance when you knock on it, but it
still sounds just fine.

Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

Subject: Question on the Type of Wood Used in Speaker Construction and
Effect on Sound
From: (Detector195)
Date: 5/26/04 9:12 PM Mountain Daylight Time
Message-id:

(Chu Gai) wrote in message
.com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.




Nope, a Xylophone is by built with wood bars.

It is in a different pitch range than a Marimba.

Back to speakers, You do not want the box to resonate and 1-1/2 " particle
board will work very well for a speaker box.

If you want it to look nice, just apply wood veneer.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

(Chu Gai) wrote in message . com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced

Ah, the anthropological view. Of course.

(Chu Gai) wrote in message . com...

and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.

I looked up the properties of different woods in the CRC Handbook of
Chemistry and Physics. There is a fair amount of variation in density
and Young's modulus, but not enough to account for 5 octaves. And if
the keys are made out of wood, it's called a marimba.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced

Ah, the anthropological view. Of course.

[[email protected]]

On Tuesday, May 25, 2004 8:45:45 PM UTC-7, Chu Gai wrote:
A brief discussion on resolving systems with a gentleman who makes
single driver speakers in what appears to be a folded Voigt Pipe
design turned briefly to resonances. My general contention was that
since he was using alder as opposed to MDF, that it would result in
additional resonances which would color the sound. Some mild umbrage
was taken. The conversation went like this. Am I somehow missing
something here or is this a combination of spin coupled with some
factual errors regarding wood?

Him: Sure, it will resonate. So will wood, steel, micarta, MDF, and
ANYTHING ELSE that has any mechanical stiffness. How it resonates and
whether it's important depends upon its stiffness, it's internal
mechanical losses, how it's mounted and secured and how it's
mechanically loaded and acoustically excited.

Me: This should not be interpreted as the intentional use of materials
to impart resonances as opposed to MDF which has a more predictable
nature? In ways, it reminds me of the various woods that can be used
in the construction of guitars where I think MDF, apart from being
heavy, might not make for the most pleasing of sounds.

Him: No, you have interpreted incorrectly. A common misconception
though. But yes woods do flavor sound, for guitars and speakers. Part
of woods amazing quality is that it can be made to resonate more, as
in the case of a guitar or piano, but that same piano usues wood to
isolate the vibration (the case) so the most energy can be released to
the room (more music)
What solid wood does in the case of my speaker is resonate LESS. I use
solid wood for it's weight vs ridgidity, it is far more ridgid than
mdf. And contributes actually less in the form of self -resonance. In
addition we have have made this speaker from teak, oak, mdf, plywood,
pine, alder, maple and cherry. All have distinct sonic "flavors". The
solid wood particularly the maple extends bass and allows the very
absolute maximum energy transfer from driver cone to port to room
without imparting audible resonance of it's own. The mdf example
sounded muffled and lifeless. My designs pursue maximum energy
transfer from electrical to the room both from the front of the driver
and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.
One really has to integrate decisions about grain orientation,
thicknesses of wood as well as joint strength to carry this discussion
comparing materials to any logical extent as it relates to
speakerbuilding.

Me: If it's your position that cabinet augmentation is desireable,
then we stand on opposite sides. If you feel that it gives your
speaker a characteristic sound that is pleasing, I can live with that.

Him: The concept that you propose I subscribe to is incorrect, you
mis-nterpret my intention of reducing resonance through the use of
solid wood. MDf does not eliminate resonance. It reduces it
drastically, such that it also reduces musical content via energy
absorption.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced
with machinery. The square box (usually sealed or ported0 became the
de-facto method of augmenting the bass drivers own free-air resonance
(fs) or limiting it in the case of sealed enclosures. I submit this
has every thing to do with the advent of high powered solid state
amplifiers as equally as declining skills in our labor pool. MDF was
not created for eliminating resonance in speaker boxes but rather to
utilize vast stretches of inadequate lumber stocks. From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

MDF is the best for creating acoustical energy in any room

[Trevor]

MDF is the best for creating acoustical energy in any room

What a stupid statement. VERY few musical instruments use MDF, (when was
the last time you saw a Piano made from MDF?) and even many good speaker
boxes use plywood rather than MDF.
In any case the sound from a speaker should come from the cone, not the
box, and apart from it's obvious drawbacks, concrete is far better than
MDF for speakers, so MDF can hardly be "best" for anything.
Acceptable, perhaps.

Trevor.

[Peter Larsen[_3_]]

"Trevor" skrev i en meddelelse
...


MDF is the best for creating acoustical energy in any room

What a stupid statement. VERY few musical instruments use MDF, (when was
the last time you saw a Piano made from MDF?) and even many good speaker
boxes use plywood rather than MDF.
In any case the sound from a speaker should come from the cone, not the
box, and apart from it's obvious drawbacks, concrete is far better than
MDF for speakers, so MDF can hardly be "best" for anything.

Acceptable, perhaps.

No, it can not be said like that. It is not a rigid material, so it becomes
very much a matter of how the box is braced. The "best material" is quite
likely to be a composite structure.

Example: Briggs "Loudspeakers" has as an example of a good construction
concept a corner bass reflex box built of bricks and mortar with a 12"
loudspeaker mounted on a plywood panel for ease of fitting. It is many ears
ago I borrowed the book from Duelund and read it, but I tend to think that
Briggs expressed preference for bricks and mortar over concrete.

Trevor

Kind regards

Peter Larsen

[David Platt]

MDF is the best for creating acoustical energy in any room

*sigh*

Yet another person posting a reply to a query that was ten years old!
(The original request was posted back in 2004).


What a stupid statement. VERY few musical instruments use MDF, (when was
the last time you saw a Piano made from MDF?) and even many good speaker
boxes use plywood rather than MDF.
In any case the sound from a speaker should come from the cone, not the
box, and apart from it's obvious drawbacks, concrete is far better than
MDF for speakers, so MDF can hardly be "best" for anything.

Acceptable, perhaps.

No, it can not be said like that. It is not a rigid material, so it becomes
very much a matter of how the box is braced. The "best material" is quite
likely to be a composite structure.

Example: Briggs "Loudspeakers" has as an example of a good construction
concept a corner bass reflex box built of bricks and mortar with a 12"
loudspeaker mounted on a plywood panel for ease of fitting. It is many ears
ago I borrowed the book from Duelund and read it, but I tend to think that
Briggs expressed preference for bricks and mortar over concrete.

I'd put it this way: MDF is one of the better compromise materials
that's easily available to the speaker home-builder. It's got good
dimensional stability, it's not difficult to work with homeowner-grade
tools, it glues and screws together easily, it's easy to paint or
veneer, it's strong enough to be routed for a speaker-flange recess,
and (unlike some common plywood) it won't have hidden voids or
loosely-glued sublayers which could buzz at embarrassing moments.
It's available in convenient-sized sheets from your local homebuilding
store... easier to find and afford than void-free Baltic birch
marine-grade plywood (another favorite).

On the down side: it wears out tool-steel saw blades quickly (use
carbide!), it's heavy, it's not all that rigid (you're right, good
bracing is very important), and it can crumble at the corners if
struck. And, of course, Stradivarius didn't ever mill any of his
better violins out of it :-)

I put together a big floor-standing system a couple of decades ago,
made mostly out of MDF - still very happy with the results. I did do
a bunch of internal bracing, made the front baffle out of two sheets
glued together (with some damping between the layers), and damped the
whole interior of the box with an elastomer paste. The resulting box
is quite acoustically "dead"... but man, is it ever *heavy*!

I was tempted to try a more exotic composite design... thin walls of
something stiff, with an interposing layer of a gridded plastic
stiffener (e.g. fluorescent-light diffuser) filled with fine sand for
damping. I decided that discretion was the better part of valor,
though... putting something like that together for a fairly complex
cabinet shape was beyond my skill-and-equipment set.

I do remember seeing a picture of Ray Dolby's listening room years
ago. Five huge exponential horn systems (three in front, and two in
back) built into the building structure, composed of masonry of some
sort (I can't recall whether it was brick-and-mortar, or cinderblock
filled with sand). I think he used a whole rack full of Flame Linear
400 amps to power the drivers.

I'm sure that was a system that you didn't *need* to turn up to 11!

[geoff]

On 25/09/2014 6:46 a.m., David Platt wrote:

On the down side: it wears out tool-steel saw blades quickly (use
carbide!), it's heavy, it's not all that rigid (you're right, good
bracing is very important), and it can crumble at the corners if
struck. And, of course, Stradivarius didn't ever mill any of his
better violins out of it :-)


That's what makes MDF *great* for speakers. You DON'T WANT your cabinet
resonating and radiating sound - you want it as insert as possible,
exactly the opposite of the case with violins, guitars, pianos, drums, etc.

Except for Danelectro of course....

geoff

[Shaun]

wrote in message
...

On Tuesday, May 25, 2004 8:45:45 PM UTC-7, Chu Gai wrote:
A brief discussion on resolving systems with a gentleman who makes
single driver speakers in what appears to be a folded Voigt Pipe
design turned briefly to resonances. My general contention was that
since he was using alder as opposed to MDF, that it would result in
additional resonances which would color the sound. Some mild umbrage
was taken. The conversation went like this. Am I somehow missing
something here or is this a combination of spin coupled with some
factual errors regarding wood?

Him: Sure, it will resonate. So will wood, steel, micarta, MDF, and
ANYTHING ELSE that has any mechanical stiffness. How it resonates and
whether it's important depends upon its stiffness, it's internal
mechanical losses, how it's mounted and secured and how it's
mechanically loaded and acoustically excited.

Me: This should not be interpreted as the intentional use of materials
to impart resonances as opposed to MDF which has a more predictable
nature? In ways, it reminds me of the various woods that can be used
in the construction of guitars where I think MDF, apart from being
heavy, might not make for the most pleasing of sounds.

Him: No, you have interpreted incorrectly. A common misconception
though. But yes woods do flavor sound, for guitars and speakers. Part
of woods amazing quality is that it can be made to resonate more, as
in the case of a guitar or piano, but that same piano usues wood to
isolate the vibration (the case) so the most energy can be released to
the room (more music)
What solid wood does in the case of my speaker is resonate LESS. I use
solid wood for it's weight vs ridgidity, it is far more ridgid than
mdf. And contributes actually less in the form of self -resonance. In
addition we have have made this speaker from teak, oak, mdf, plywood,
pine, alder, maple and cherry. All have distinct sonic "flavors". The
solid wood particularly the maple extends bass and allows the very
absolute maximum energy transfer from driver cone to port to room
without imparting audible resonance of it's own. The mdf example
sounded muffled and lifeless. My designs pursue maximum energy
transfer from electrical to the room both from the front of the driver
and the rear.. I once made a xylephone from different species of wood,
the keys all the same size as an experiment. 5 octaves were covered
just from locally growing trees.
One really has to integrate decisions about grain orientation,
thicknesses of wood as well as joint strength to carry this discussion
comparing materials to any logical extent as it relates to
speakerbuilding.

Me: If it's your position that cabinet augmentation is desireable,
then we stand on opposite sides. If you feel that it gives your
speaker a characteristic sound that is pleasing, I can live with that.

Him: The concept that you propose I subscribe to is incorrect, you
mis-nterpret my intention of reducing resonance through the use of
solid wood. MDf does not eliminate resonance. It reduces it
drastically, such that it also reduces musical content via energy
absorption.

If you look at speakerbuilding from another angle, the anthropological
veiw, we see that as forests shrank and skilled labor was replaced
with machinery. The square box (usually sealed or ported0 became the
de-facto method of augmenting the bass drivers own free-air resonance
(fs) or limiting it in the case of sealed enclosures. I submit this
has every thing to do with the advent of high powered solid state
amplifiers as equally as declining skills in our labor pool. MDF was
not created for eliminating resonance in speaker boxes but rather to
utilize vast stretches of inadequate lumber stocks. From an acoustical
standpoint MDF is dampening. It absorbs sound due to it's mass and
weight.

I am trying to allow the energy that would be absorbed by MDF to be
better utilized re-creating acoustical energy in the room. Of course
you do not want your speakerbox to vibrate, but using a "dead" panel
is the easy way out and not neccesarily the best method. ANd I think
Franco Serbelin agrees.

MDF is the best for creating acoustical energy in any room



Try using morning wood. It might be interesting.

Shaun

[Trevor]

On 7/10/2014 1:54 PM, Shaun wrote:

MDF is the best for creating acoustical energy in any room


Not this again, if it was the "best for creating acoustical energy in
any room" all wooden acoustical musical instruments would be made from
it instead of none.

Trevor.

[Shaun]

"Trevor" wrote in message ...

On 7/10/2014 1:54 PM, Shaun wrote:

MDF is the best for creating acoustical energy in any room


Not this again, if it was the "best for creating acoustical energy in
any room" all wooden acoustical musical instruments would be made from
it instead of none.

Trevor.

Hey Trevor;

Do a google search for Morning wood; I don't think you know what it is.

Shaun

[Trevor]

On 8/10/2014 3:15 AM, Shaun wrote:
"Trevor" wrote in message ...
On 7/10/2014 1:54 PM, Shaun wrote:

MDF is the best for creating acoustical energy in any room


Not this again, if it was the "best for creating acoustical energy in
any room" all wooden acoustical musical instruments would be made from
it instead of none.


Hey Trevor;

Do a google search for Morning wood; I don't think you know what it is.

Sure I do, but what has it got to do with this thread?

Trevor.