[genericaudioperson]

Hello,

Sharp spikes are often put on the bottom of speakers to keep them from
moving when a loud bass note is hit. But then there are those
Auralex Mopads. Those would do the opposite I would think. Wouldn't
those pads make the speakers fly back and forth? These seem to be
contradictory solutions to "tighten up the bass"

[Don Pearce]

On Sun, 7 Dec 2008 08:35:16 -0800 (PST), genericaudioperson
wrote:

Hello,

Sharp spikes are often put on the bottom of speakers to keep them from
moving when a loud bass note is hit. But then there are those
Auralex Mopads. Those would do the opposite I would think. Wouldn't
those pads make the speakers fly back and forth? These seem to be
contradictory solutions to "tighten up the bass"

Neither makes any difference to the sound. The purpose of the spikes
is to allow the speaker to stand on carpet without wrecking it. The
purpose of the Monopads is to part the ignorant from his money.

d
--
Pearce Consulting
http://www.pearce.uk.com

[Laurence Payne[_2_]]

Sharp spikes are often put on the bottom of speakers to keep them from
moving when a loud bass note is hit. But then there are those
Auralex Mopads. Those would do the opposite I would think. Wouldn't
those pads make the speakers fly back and forth? These seem to be
contradictory solutions to "tighten up the bass"

Absolutely. The various "solutions" beloved of audiophools are often
self-contradictory.

[Mike Rivers]

genericaudioperson wrote:

Auralex Mopads. Those would do the opposite I would think. Wouldn't
those pads make the speakers fly back and forth? These seem to be
contradictory solutions to "tighten up the bass"

They keep the speaker cabinets from turning the shelf that you put them
on into a secondary radiator. Then there's the Primacoustic Recoil
Stabilizers, a heavy metal slab with a pad under it that you set your
speakers on. This is the one that perfectly sensible people say really
improves the sound. It works (simplistic explanation warning!) by adding
mass to the speaker cabinet so it won't act as a secondary radiator.
They demonstrate it by comparing a speaker on a Recoil Stabilizer with
one on a piece of foam like a MoPad.

When I was talking with a Primacoustic rep at a NAMM show and told him
that I had my monitors on a stack of concrete blocks, he said "Well, you
don't need these."

Spikes couple the energy from the floppy speaker cabinet to the floor,
which is exactly what you don't want to do.



--
If you e-mail me and it bounces, use your secret decoder ring and reach
me he
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Ty Ford]

On Sun, 7 Dec 2008 14:20:24 -0500, Mike Rivers wrote
(in article ):

genericaudioperson wrote:

Auralex Mopads. Those would do the opposite I would think. Wouldn't
those pads make the speakers fly back and forth? These seem to be
contradictory solutions to "tighten up the bass"

They keep the speaker cabinets from turning the shelf that you put them
on into a secondary radiator. Then there's the Primacoustic Recoil
Stabilizers, a heavy metal slab with a pad under it that you set your
speakers on. This is the one that perfectly sensible people say really
improves the sound. It works (simplistic explanation warning!) by adding
mass to the speaker cabinet so it won't act as a secondary radiator.
They demonstrate it by comparing a speaker on a Recoil Stabilizer with
one on a piece of foam like a MoPad.

When I was talking with a Primacoustic rep at a NAMM show and told him
that I had my monitors on a stack of concrete blocks, he said "Well, you
don't need these."

Spikes couple the energy from the floppy speaker cabinet to the floor,
which is exactly what you don't want to do.

In the old days, at radio stations, some of the turntable bases were filled
with a couple of cubic feet of sand.

They were a bitch to move..which was the point, as regards the cartridge and
stylus.

Regards,

Ty Ford



--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA

[William Sommerwerck]

I've never seen any systematic studies of the audible or measurable benefits
of speaker spikes.

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move. It
couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

[Scott Dorsey]

William Sommerwerck wrote:
I've never seen any systematic studies of the audible or measurable benefits
of speaker spikes.

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move. It
couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

Yes, but it would seem that there are many better ways to do it than to
use spikes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

"William Sommerwerck" wrote in
message

I've never seen any systematic studies of the audible or
measurable benefits of speaker spikes.

They are calculably and measurably so trivial that it is hard to get up much
enthusiasm for a listening test.

But they're not inherently stupid or useless. Unless the
drivers are thoroughly decoupled from the cabinet, they
make the cabinet move.

If you do the math, the motion is trivial. BTW, cones really work! ;-)

It couldn't hurt to couple the
cabinet to the floor, to provide a partial "sink" for
these vibrations.

When what you're coupling is trivial, whatever you do with that trivial
something, makes no significant difference.

[Richard Crowley]

"Scott Dorsey" wrote ...
William Sommerwerck wrote:
I've never seen any systematic studies of the audible or measurable
benefits
of speaker spikes.

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move. It
couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

Yes, but it would seem that there are many better ways to do it than to
use spikes.

Maybe their room has shag carpeting from the 1970s :-)

The depth of the shag (where it wasn't matted down) may
have made it acoustically effective maybe even down into
the upper-mid-range! :-))

[William Sommerwerck]

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move.
It couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

Yes, but it would seem that there are many better ways to do it
than to use spikes.

Perhaps. Some people see spikes as a form of coupling, while others feel
they provide de-coupling. Confusing.

[William Sommerwerck]

It couldn't hurt to couple the cabinet to the floor, to provide
a partial "sink" for these vibrations.

When what you're coupling is trivial, whatever you do with
that trivial something, makes no significant difference.

Probably. However, the issue of directly damping the cabinet's surfaces is
something else. I'm not in the mood to discuss it right now.

[GregS[_3_]]

In article , "Richard Crowley" wrote:
"Scott Dorsey" wrote ...
William Sommerwerck wrote:
I've never seen any systematic studies of the audible or measurable
benefits
of speaker spikes.

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move. It
couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

If you decouple the drivers, the air still vibrates inside causing motions on all
surfaces. It would seem spikes would have the most effect
on vertical vibrations. Each cabinet will have different vibrations. The best
have little vibration. A cement floor would seem best. A flimsy woofen floor
is going to move or vibrate the most. To put a spike of a speaker
on a cenent floor, you want a spike that can give a little. Regardless
of spikes, the sound in the room is going to vibrate the floor
anyway.

I'm sure there have been recorded tests, and I know for sure tests
are done on cabinets alone to see what frequencies are resonating
in the cabinet. Spikes may transfer these resonances but will
have little effect on reducing them, unless they are canceled with
another vibration source 180 degrees out of phase.

greg

Yes, but it would seem that there are many better ways to do it than to
use spikes.

Maybe their room has shag carpeting from the 1970s :-)

The depth of the shag (where it wasn't matted down) may
have made it acoustically effective maybe even down into
the upper-mid-range! :-))

[Mike Rivers]

Ty Ford wrote:

In the old days, at radio stations, some of the turntable bases were filled
with a couple of cubic feet of sand.

So were the walls of speaker enclosures. It's still probably better than
3/4" MDF but a lot heavier (good) and messier (bad) if you have
termites. G



--
If you e-mail me and it bounces, use your secret decoder ring and reach
me he
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Ray Thomas[_2_]]

"GregS" wrote in message
...
In article , "Richard
Crowley" wrote:
"Scott Dorsey" wrote ...
William Sommerwerck wrote:
I've never seen any systematic studies of the audible or measurable
benefits
of speaker spikes.

But they're not inherently stupid or useless. Unless the drivers are
thoroughly decoupled from the cabinet, they make the cabinet move. It
couldn't hurt to couple the cabinet to the floor, to provide a partial
"sink" for these vibrations.

If you decouple the drivers, the air still vibrates inside causing motions
on all
surfaces. It would seem spikes would have the most effect
on vertical vibrations. Each cabinet will have different vibrations. The
best
have little vibration. A cement floor would seem best. A flimsy woofen
floor
is going to move or vibrate the most. To put a spike of a speaker
on a cenent floor, you want a spike that can give a little. Regardless
of spikes, the sound in the room is going to vibrate the floor
anyway.

I'm sure there have been recorded tests, and I know for sure tests
are done on cabinets alone to see what frequencies are resonating
in the cabinet. Spikes may transfer these resonances but will
have little effect on reducing them, unless they are canceled with
another vibration source 180 degrees out of phase.

greg

Yes, but it would seem that there are many better ways to do it than to
use spikes.

Maybe their room has shag carpeting from the 1970s :-)

The depth of the shag (where it wasn't matted down) may
have made it acoustically effective maybe even down into
the upper-mid-range! :-))


My understanding (of the sales pitch/marketing ?) of the function of cones
or spikes was that they were supposed to act as a 'physical diode'..in other
words to allow unwanted vibrations and micro-motion to transfer from the
speaker cabinet into the thick end of the cone and then down through its
point to a massy, inert body below it (floor, shelf, concrete slab etc)
which would then absorb the vibes and in theory refuse to allow them to be
reflected back up the spike/cone again ? I don't know how complete this
diode principle was meant to be, in terms of allowing one way transmission
of kinetic energy only ? Wouldn't that depend on a gradation of absorptive
materials on the downwards path so that 'reflections' of energy wouldn't
travel back up the cone again ...? So if the cone point terminated in a
full sandbox, for example, that would presumably act as an energy-sink.
Dunno, that's my shaky (ha !) understanding of the "theory" anyway.
RT

[David Grant]

My understanding (of the sales pitch/marketing ?) of the function of cones
or spikes was that they were supposed to act as a 'physical diode'..in
other words to allow unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and then down through
its point to a massy, inert body below it (floor, shelf, concrete slab
etc) which would then absorb the vibes and in theory refuse to allow them
to be reflected back up the spike/cone again ? I don't know how complete
this diode principle was meant to be, in terms of allowing one way
transmission of kinetic energy only ? Wouldn't that depend on a gradation
of absorptive materials on the downwards path so that 'reflections' of
energy wouldn't travel back up the cone again ...? So if the cone point
terminated in a full sandbox, for example, that would presumably act as an
energy-sink. Dunno, that's my shaky (ha !) understanding of the "theory"
anyway.
RT


I studied transmission lines from an electrical engineering standpoint a few
years ago and I expect this represents the mechanical equivalent. It should
be possible to minimize vibration reflections at the termination via
impedance matching (where impedance in this case is a complex value based on
mass, spring, damping).

The diode analogy sounds iffy. The direction of elecron flow can be
controlled using charges but a vibration carries no polarity. I don't
believe an atom of matter has any means with which to determine whether a
vibration came from direction x or direction -x. It would have to
communicate with adjacent members to determine the direction of propogation,
and then somehow it would have to absorb that energy or transmit it
depending on the case. That doesn't sound like a natural property of matter.

[GregS[_3_]]

In article , "David Grant" wrote:

My understanding (of the sales pitch/marketing ?) of the function of cones
or spikes was that they were supposed to act as a 'physical diode'..in
other words to allow unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and then down through
its point to a massy, inert body below it (floor, shelf, concrete slab
etc) which would then absorb the vibes and in theory refuse to allow them
to be reflected back up the spike/cone again ? I don't know how complete
this diode principle was meant to be, in terms of allowing one way
transmission of kinetic energy only ? Wouldn't that depend on a gradation
of absorptive materials on the downwards path so that 'reflections' of
energy wouldn't travel back up the cone again ...? So if the cone point
terminated in a full sandbox, for example, that would presumably act as an
energy-sink. Dunno, that's my shaky (ha !) understanding of the "theory"
anyway.
RT


I studied transmission lines from an electrical engineering standpoint a few
years ago and I expect this represents the mechanical equivalent. It should
be possible to minimize vibration reflections at the termination via
impedance matching (where impedance in this case is a complex value based on
mass, spring, damping).

The diode analogy sounds iffy. The direction of elecron flow can be
controlled using charges but a vibration carries no polarity. I don't
believe an atom of matter has any means with which to determine whether a
vibration came from direction x or direction -x. It would have to
communicate with adjacent members to determine the direction of propogation,
and then somehow it would have to absorb that energy or transmit it
depending on the case. That doesn't sound like a natural property of matter.

I suspect someone looked at the spikes one day and made a conclusion
for no good reason. The spikes does go through carpeting and touch the floor, which
for no other reason keep the speaker from rocking back and forth on the rug.
I think I have also seen spikes which look more like nails. I would rather
have the speaker on the rug, but the spikes look pretty both on the rug and
on a wooden floor, except when you try to slide them.

greg

[Arny Krueger]

"Ray Thomas" wrote in message


My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from the
speaker cabinet into the thick end of the cone and then
down through its point to a massy, inert body below it
(floor, shelf, concrete slab etc) which would then absorb
the vibes and in theory refuse to allow them to be
reflected back up the spike/cone again ?

That crashing sound you hear in the background is several laws of physics
breaking. ;-)

It is possible to make the mechanical equivalent of a diode, but it won't be
a simple cone of metal.

If you actually had one, a mechanical diode won't do what was described
above.

However the biggest fallacy is the idea that there will be significant
vibrations of the speaker cabinet.

Speaker cones really work! Everything else works not so well.

[thepaulthomas]

On Dec 9, 10:11*am, "Arny Krueger" wrote:
"Ray Thomas" wrote in message



My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from the
speaker cabinet into the thick end of the cone and then
down through its point to a massy, inert body below it
(floor, shelf, concrete slab etc) which would then absorb
the vibes and in theory refuse to allow them to be
reflected back up the spike/cone again ?

However the biggest fallacy is the idea that there will be significant
vibrations of the speaker cabinet.

Does that mean building speaker cabinets of heavier materials is
pointless?

[GregS[_3_]]

In article , thepaulthomas wrote:
On Dec 9, 10:11=A0am, "Arny Krueger" wrote:
"Ray Thomas" wrote in message



My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from the
speaker cabinet into the thick end of the cone and then
down through its point to a massy, inert body below it
(floor, shelf, concrete slab etc) which would then absorb
the vibes and in theory refuse to allow them to be
reflected back up the spike/cone again ?

However the biggest fallacy is the idea that there will be significant
vibrations of the speaker cabinet.

Does that mean building speaker cabinets of heavier materials is
pointless?

Not at all. Thats why they don't vibrate much. Even if you meagerly
try to build something that you think might work, you still have to be carefull.
By using proper damping and bracing, you can get away with poorer materials.

I once built a small bass box for the truck. For some strange reason it
vibrated like hell. I also has a power amp mounted on the side. Several
components broke loose and I had to solder them back onto the board.
It was a lesson learned.

greg

[Arny Krueger]

"thepaulthomas"
wrote in message

On Dec 9, 10:11 am, "Arny Krueger"
wrote:

"Ray Thomas" wrote in message



My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and
then down through its point to a massy, inert body
below it (floor, shelf, concrete slab etc) which would
then absorb the vibes and in theory refuse to allow
them to be reflected back up the spike/cone again ?

However the biggest fallacy is the idea that there will
be significant vibrations of the speaker cabinet.

Does that mean building speaker cabinets of heavier
materials is pointless?

No, but its all a matter of diminishing returns.

Also, if you want a stiff cabinet, after a certain point, additional wood is
better allocated to internal bracing.

[thepaulthomas]

On Dec 9, 1:35*pm, "Arny Krueger" wrote:
"thepaulthomas"
wrote in



On Dec 9, 10:11 am, "Arny Krueger"
wrote:
"Ray Thomas" wrote in message

My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and
then down through its point to a massy, inert body
below it (floor, shelf, concrete slab etc) which would
then absorb the vibes and in theory refuse to allow
them to be reflected back up the spike/cone again ?
However the biggest fallacy is the idea that there will
be significant vibrations of the speaker cabinet.
Does that mean building speaker cabinets of heavier
materials is pointless?

No, but its all a matter of diminishing returns.

Also, if you want a stiff cabinet, after a certain point, additional wood is
better allocated to internal bracing.

OK, gotcha. Thanks, Arny. Now what about things like concrete
cabinets? I have a small pair of Rauna speakers that I like and they
are made of concrete. Even though they are "bookshelf" size speakers
they weigh about 45 pounds each. Would you consider that type of
construction to be way beyond the point of diminishing returns or
would the significantly heavier concrete walls just be similar in
effect to the extra bracing you mentioned?

[Scott Dorsey]

thepaulthomas wrote:

OK, gotcha. Thanks, Arny. Now what about things like concrete
cabinets? I have a small pair of Rauna speakers that I like and they
are made of concrete. Even though they are "bookshelf" size speakers
they weigh about 45 pounds each. Would you consider that type of
construction to be way beyond the point of diminishing returns or
would the significantly heavier concrete walls just be similar in
effect to the extra bracing you mentioned?

That depends if you have to pay the shipping cost on them, and if you
have to carry them around a lot.

The holy grail, of course, is a lightweight cabinet that is nonresonant
and can stand being dropped repeatedly. We don't have this, but the
carbon composites get better every year.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[thepaulthomas]

On Dec 9, 1:50*pm, (Scott Dorsey) wrote:
thepaulthomas wrote:

OK, gotcha. Thanks, Arny. Now what about things like concrete
cabinets? I have a small pair of Rauna speakers that I like and they
are made of concrete. Even though they are "bookshelf" size speakers
they weigh about 45 pounds each. Would you consider that type of
construction to be way beyond the point of diminishing returns or
would the significantly heavier concrete walls just be similar in
effect to the extra bracing you mentioned?

That depends if you have to pay the shipping cost on them, and if you
have to carry them around a lot.

The holy grail, of course, is a lightweight cabinet that is nonresonant
and can stand being dropped repeatedly. *We don't have this, but the
carbon composites get better every year.
--scott
--
"C'est un Nagra. *C'est suisse, et tres, tres precis."

I bought the Rauna's used for $50 on eBay and paid another $50 for
shipping so I really can't complain. However, the original owner that
had them shipped from Sweden must have had one hell of a freight
bill. ;-)

[Ray Thomas[_2_]]

"GregS" wrote in message
...
In article , "David Grant"
wrote:

My understanding (of the sales pitch/marketing ?) of the function of
cones
or spikes was that they were supposed to act as a 'physical diode'..in
other words to allow unwanted vibrations and micro-motion to transfer
from
the speaker cabinet into the thick end of the cone and then down through
its point to a massy, inert body below it (floor, shelf, concrete slab
etc) which would then absorb the vibes and in theory refuse to allow
them
to be reflected back up the spike/cone again ? I don't know how
complete
this diode principle was meant to be, in terms of allowing one way
transmission of kinetic energy only ? Wouldn't that depend on a
gradation
of absorptive materials on the downwards path so that 'reflections' of
energy wouldn't travel back up the cone again ...? So if the cone point
terminated in a full sandbox, for example, that would presumably act as
an
energy-sink. Dunno, that's my shaky (ha !) understanding of the "theory"
anyway.
RT


I studied transmission lines from an electrical engineering standpoint a
few
years ago and I expect this represents the mechanical equivalent. It
should
be possible to minimize vibration reflections at the termination via
impedance matching (where impedance in this case is a complex value based
on
mass, spring, damping).

The diode analogy sounds iffy. The direction of elecron flow can be
controlled using charges but a vibration carries no polarity. I don't
believe an atom of matter has any means with which to determine whether a
vibration came from direction x or direction -x. It would have to
communicate with adjacent members to determine the direction of
propogation,
and then somehow it would have to absorb that energy or transmit it
depending on the case. That doesn't sound like a natural property of
matter.

I suspect someone looked at the spikes one day and made a conclusion
for no good reason. The spikes does go through carpeting and touch the
floor, which
for no other reason keep the speaker from rocking back and forth on the
rug.
I think I have also seen spikes which look more like nails. I would rather
have the speaker on the rug, but the spikes look pretty both on the rug
and
on a wooden floor, except when you try to slide them.

greg

You are obviously far too pragmatic and sensible about resonance physics, so
let me provoke a little controversy by introducing you to the black arts of
Shun Mook, which have been around for many years now. Now let's see...these
should stir the pot sufficiently, at least for the entree course ;-)

http://www.shunmook.com/text1.htm

http://www.shunmook.com/text2.htm and for comprehensive overview
http://www.stereophile.com/features/69/ (10+ pages of followup and
reader's replies too !)

Ray

[Eric B]

On Dec 7, 11:35*am, genericaudioperson
wrote:
Hello,

Sharp spikes are often put on the bottom of speakers to keep them from
moving when a loud bass note is hit. * But then there are those
Auralex Mopads. *Those would do the opposite I would think. *Wouldn't
those pads make the speakers fly back and forth? *These seem to be
contradictory solutions to "tighten up the bass"

Dear Generic...
The spikes are from Hifi. The science is iffy. Perhaps they
stabilize the loading of the speaker stand. The only advantage I can
think of is to connect the bass to the floor in a point loaded
fashion.
The advantage of de-coupling speakers from a work station is real.
OTOH, the foam isolation units don't work as well as a free standing,
massive stand like cinder blocks.
I used to believe as several have stated here that there could be no
significant advantage to stand mounting over shelf mounting. I was
wrong! The issue was irrefutably demonstrated to me while showing a
high end NY jazz producer the Earthworks speakers. On stands the bass
image was beautiful. As soon as the speakers were put on a table or
shelf the bass image went away completely. The best explanation
(rationalization)II could come up with was that A) the entire
workstation becomes a bass radiator and B) that the bass information
from the two speakers 'talks' to each other through the hard physical
medium of the wood like substance and the differences are hidden.
I understand that many people believe bass imaging is stupid or
perhaps ill-conceived. I have heard all sorts of explanations why bass
image can not possibly be perceived.
Anyone want to argue that subject?
Best regards,
Eric Blackmer

[Scott Dorsey]

Eric B wrote:
Dear Generic...
The spikes are from Hifi. The science is iffy. Perhaps they
stabilize the loading of the speaker stand. The only advantage I can
think of is to connect the bass to the floor in a point loaded
fashion.

I think this is true. I think also that they don't do anything that
isn't better done by adding mass. And they tear up your floors.

The advantage of de-coupling speakers from a work station is real.
OTOH, the foam isolation units don't work as well as a free standing,
massive stand like cinder blocks.

Mass is always your friend.

I used to believe as several have stated here that there could be no
significant advantage to stand mounting over shelf mounting. I was
wrong! The issue was irrefutably demonstrated to me while showing a
high end NY jazz producer the Earthworks speakers. On stands the bass
image was beautiful. As soon as the speakers were put on a table or
shelf the bass image went away completely. The best explanation
(rationalization)II could come up with was that A) the entire
workstation becomes a bass radiator and B) that the bass information
from the two speakers 'talks' to each other through the hard physical
medium of the wood like substance and the differences are hidden.

The low end really adds a lot to the perception of the stereo image and
a lot of things that people notice as changing the image often are
really the result in changes in bass tonality.

But, if you want a really bad example, take those same speakers and hang
them from the ceiling with ropes of chains, as is STILL commonly done
in broadcast studios. The low end is totally screwed up, even more than
on the table.

I understand that many people believe bass imaging is stupid or
perhaps ill-conceived. I have heard all sorts of explanations why bass
image can not possibly be perceived.

The problem is that people misinterpret the science. If you look at the
studies, there is good proof that actual imaging does not exist for anything
below about 20 Hz. This means that a second order crossover into a mono
subwoofer has to be located at 10 Hz to make sure there isn't substantial
energy above 20 Hz being made mono... which kind of defeats most subwoofers
completely. People handwave this and say "there's no bass imaging" when
they are talking about stuff in the 100 Hz range several octaves up.

Bass imaging comes from arrival time differences at the ear, and if you
think about the mechanism, you can see that at 20 Hz there is a pretty
small fraction of a wavelength between the two ears. But yet, there's
still some audible difference possible.

All of this is confounded by my earlier point that tonal changes in the
low end change perceived imaging.

Anyone want to argue that subject?

There's too much stuff going on to argue either way without knowing the
real circumstances of the playback system. That's why instead I am going
to go listen to another Jaco Pastorius record.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

Mass is always your friend.

Tell Oprah that.

[Arny Krueger]

"Eric B" wrote in message

On Dec 7, 11:35 am, genericaudioperson
wrote:
Hello,

Sharp spikes are often put on the bottom of speakers to
keep them from moving when a loud bass note is hit.

Never had much problem with my speakers moving when I put them on
rubber-tipped feet.

But then there are those Auralex Mopads.

Well, they reposition and reorient your speakers, if the PR is any guide.


Those would do the opposite I would
think. Wouldn't those pads make the speakers fly back
and forth? These seem to be contradictory solutions to
"tighten up the bass"

If you want to tighten up the bass, check out this web site:

http://www.realtraps.com/

The spikes are from Hifi. The science is iffy. Perhaps
they stabilize the loading of the speaker stand. The only
advantage I can think of is to connect the bass to the
floor in a point loaded fashion.

Why would point loading be advantageous?

The advantage of de-coupling speakers from a work
station is real.

Really?

OTOH, the foam isolation units don't
work as well as a free standing, massive stand like
cinder blocks.

You're comparing apples and radishes. Yes both are red on the outside and
white on the inside, but... ;-)

Speakers are like houses and businesses, its all about location,, and
location. Well, location and orientation.

If you want to compare foam isolation units and free-standing stands, hold
location and orientation constant while you add and remove the foam blocks.
Otherwise, all you're doing is proving me right about the importance of
location and orientation.

I used to believe as several have stated
here that there could be no significant advantage to
stand mounting over shelf mounting.

Ever compare a stand and a shelf while holding location and orientation the
same? But that doesn't hold location constant because the shelf places the
speaker on a long plane, or even between two long planes that may be very
significant acoustically.

I was wrong!

Hold that thought! ;-)

The
issue was irrefutably demonstrated to me while showing a
high end NY jazz producer the Earthworks speakers. On
stands the bass image was beautiful. As soon as the
speakers were put on a table or shelf the bass image went
away completely.

Yes, but location and orientation were different.

Furthermore, if you put a speaker on a table, you're putting it on top of a
planar surface that is large enough to change the acoustics around the
speaker. But I doubt that you did this while holding location and
orientation constant. So, all you did is prove me right about the importance
of location and orientation.

This is yet another example of Occam's razor. People move speaker from
standing on spikes on the floor to a position on a shelf about ear height.
Then they attribute the obvious difference in sound quality to the spikes?

The best explanation (rationalization)II
could come up with was that A) the entire workstation becomes a bass
radiator and B) that the bass information
from the two speakers 'talks' to each other through the
hard physical medium of the wood like substance and the
differences are hidden.

Or, the difference is location, orientation, and acoustical (not mechanical)
environment.

I understand that many people
believe bass imaging is stupid or perhaps
ill-conceived.

It's real, especially with small speakers.

I have heard all sorts of explanations why
bass image can not possibly be perceived.

Well, part of that depends on what you call bass. I call bass anything below
80 Hz. If you arrange your speakers correctly, then there will be minimum
perceptible directionality, but there may indeed be some. If you do what
most people do, and that is arrange the speakers where there is some space
available without changing the layout of the room, then the results are
anything from soup to nuts.

Anyone want to argue that subject?

At this point, I think I been there and done that! ;-)

[Arny Krueger]

"William Sommerwerck" wrote in
message

Mass is always your friend.

Tell Oprah that.

Baby got back! ;-)

[William Sommerwerck]

Almost 30 years ago, Jon Dahlquist accidentally discovered that painting a
speaker cabinet with 3M "fuzzy" paint (I forget the trade name)
significantly improved the sound, apparently because it dampened the
surface, preventing it from becoming a secondary radiator.

I heard a demo of this, and was surprised.

[GregS[_3_]]

In article , "Arny Krueger" wrote:
"Eric B" wrote in message

On Dec 7, 11:35 am, genericaudioperson
wrote:
Hello,

Sharp spikes are often put on the bottom of speakers to
keep them from moving when a loud bass note is hit.

Never had much problem with my speakers moving when I put them on
rubber-tipped feet.

I would imagine speakers could move on spikes. I have moved speakers before bare
wood against floor. I think rubber is a perfectly good material. Sorbothane is
probably better.

greg

[GregS[_3_]]

In article , "William Sommerwerck" wrote:
Almost 30 years ago, Jon Dahlquist accidentally discovered that painting a
speaker cabinet with 3M "fuzzy" paint (I forget the trade name)
significantly improved the sound, apparently because it dampened the
surface, preventing it from becoming a secondary radiator.

I heard a demo of this, and was surprised.

Defraction or anti-defraction rings will change the sound as well as doing the entire surface. I
have treated a number of speakers with felt like materials. It might not be a good
thing on all speakers as they are voiced as they are, but when building speakers
or modifying its a very nice thing to do. It can lift some of the cabinet edge smearing.

greg

[GregS[_3_]]

In article , (GregS) wrote:
In article , "William Sommerwerck"
wrote:
Almost 30 years ago, Jon Dahlquist accidentally discovered that painting a
speaker cabinet with 3M "fuzzy" paint (I forget the trade name)
significantly improved the sound, apparently because it dampened the
surface, preventing it from becoming a secondary radiator.

I heard a demo of this, and was surprised.

Defraction or anti-defraction rings will change the sound as well as doing the
entire surface. I
have treated a number of speakers with felt like materials. It might not be a
good
thing on all speakers as they are voiced as they are, but when building
speakers
or modifying its a very nice thing to do. It can lift some of the cabinet edge
smearing.

On the extreme end, Ken Kantor used large foam blocks on one AR speaker
design. It really limits defraction and also blocks HF sound from going too
wide.

greg

[Eric B]

On Dec 10, 11:29*am, "William Sommerwerck"
wrote:
Almost 30 years ago, Jon Dahlquist accidentally discovered that painting a
speaker cabinet with 3M "fuzzy" paint (I forget the trade name)
significantly improved the sound, apparently because it dampened the
surface, preventing it from becoming a secondary radiator.

I heard a demo of this, and was surprised.

William,
There is a bizarre effect that most people are unaware of. High
frequencies travel along a surface or boundary differently than they
move through the air. In effect the sound travels along the surface of
the box and where ever a corner, screw or surface deformity exists the
sound re-radiates making a more complex sound field. Since the ideal
speaker is a singular point source anything you can do to reduce this
re-radiation will help clarify the imaging. Rounded edges on a speaker
box also helps.
The notion of a single point source being ideal may also help
explain the importance of decoupling your speakers from the
workstation.

Someone pointed out on this thread the location, location, location
'truism' This may be true, but primarily it is due to the fact that
most speakers are awful and interact with the room poorly. In other
words, with most speakers as you move the speaker in relation to the
walls the room's acoustical issues are stimulated variously by the
problems of the speaker. If the rooms and the speakers weren't so
awful the location, location, location axiom wouldn't be true. Take
it all the way out of the room... think of it in free space. location
only matters as it relates to the relationship between you and the
speakers. And you can move. The degree to which the location model is
true relates entirely to the flaws of listening through boxes inside
of boxes. And those can to some extent be fixed. Do you need an
acoustician? http://www.blackmersound.com.
Sorry,
Eric Blackmer

[William Sommerwerck]

"Eric B" wrote in message
...
On Dec 10, 11:29 am, "William Sommerwerck"
wrote:
Almost 30 years ago, Jon Dahlquist accidentally discovered that painting a
speaker cabinet with 3M "fuzzy" paint (I forget the trade name)
significantly improved the sound, apparently because it dampened the
surface, preventing it from becoming a secondary radiator.
I heard a demo of this, and was surprised.

William,
There is a bizarre effect that most people are unaware of. High
frequencies travel along a surface or boundary differently than they
move through the air. In effect the sound travels along the surface of
the box and whereever a corner, screw or surface deformity exists the
sound re-radiates making a more complex sound field. Since the ideal
speaker is a singular point source

or a true line source ahem

anything you can do to reduce this re-radiation will help clarify the
imaging. Rounded edges on a speaker box also helps.

The biggest part of the improvement was in imaging. The effect was of a
magnitude and nature that, if I try to describe it, Arny will be doubled up
on the floor in derisive laughter. So I won't.


Someone pointed out on this thread the location, location, location
'truism' This may be true, but primarily it is due to the fact that
most speakers are awful...

QUADs, M-Ls, Apogees, etc?


and interact with the room poorly. In other
words, with most speakers as you move the speaker in relation to the
walls the room's acoustical issues are stimulated variously by the
problems of the speaker.

Even if you had a perfect point source, or a perfect line source, the room's
acoustics would still be stimulated, and likely in "bad" ways.


If the rooms and the speakers weren't so
awful the location, location, location axiom wouldn't be true.

Not so. A good speaker will be degraded by a bad room, while a bad speaker
in a good room won't be worsened.


Take it all the way out of the room... think of it in free space. location
only matters as it relates to the relationship between you and the
speakers. And you can move. The degree to which the location model is
true relates entirely to the flaws of listening through boxes inside
of boxes. And those can to some extent be fixed.

Do you need an acoustician? http://www.blackmersound.com.

Yes, but I don't have the money.

Sorry,
Eric Blackmer

[Powell]

"Arny Krueger" wrote

However the biggest fallacy is the idea that there will be significant
vibrations of the speaker cabinet.

How would you know, mr. No Experience?

Oct, 2000 , TAS - What's Wrong With Speakers
by R.E. Greene

"But as soon as a speaker gets an input signal, it
starts doing things it shouldn't and starts making
noise, not just the music it should be making. Cones
and surrounds flexing, mechanical structures
vibrating, cabinets flexing in unpredicted and
unpredictable ways, air flowing turbulently,
electrostatic diaphragms vibrating chaotically
on the scale of small areas even if they are moving
regularly on a large scale, such sources of noise
are everywhere."

"How much noise are we talking about here?
A lot, a whole lot by the standards of noise
levels in electronics and recording systems.
Speaker noise appears only 20 to 30 dB down
from signal in some cases, and even the
cleanest speakers I know do not get the noise
down much more than 55 dB or so."

[Powell]

"Don Pearce" wrote

Sharp spikes are often put on the bottom of speakers to keep
them from moving when a loud bass note is hit.

The purpose of the spikes is to allow the speaker to stand
on carpet without wrecking it.

Perpetuating USEnet myth, I see, go do your own
homework.

For maximum effectiveness spikes should not be run
through any type of carpet interface (carpet/foam).
If you have high quality carpet, spikes just won't
penetrate the carpet/pad substrate. The tightly
woven jute backing and under pad are the problem.
The conical shape of spikes simply will not couple
to the sub-floor... and I mean tightly. While it might
appear (feel) to you that your spikes are firmly in
they are still supported by the carper/pad. Sound
pressure measurements and auditioning indicate
only a poor improvement in fidelity if used in this way.

[Don Pearce[_2_]]

On Fri, 12 Dec 2008 15:41:51 -0500, "Powell"
wrote:


"Don Pearce" wrote

Sharp spikes are often put on the bottom of speakers to keep
them from moving when a loud bass note is hit.

The purpose of the spikes is to allow the speaker to stand
on carpet without wrecking it.

Perpetuating USEnet myth, I see, go do your own
homework.

For maximum effectiveness spikes should not be run
through any type of carpet interface (carpet/foam).
If you have high quality carpet, spikes just won't
penetrate the carpet/pad substrate. The tightly
woven jute backing and under pad are the problem.
The conical shape of spikes simply will not couple
to the sub-floor... and I mean tightly. While it might
appear (feel) to you that your spikes are firmly in
they are still supported by the carper/pad. Sound
pressure measurements and auditioning indicate
only a poor improvement in fidelity if used in this way.


Nonsense - you clearly have no experience in this area. The spikes do
not penetrate initially, but within an hour or so they have worked
their way through the jute backing and are making perfect contact with
the floor beneath. Meanwhile the valuable pile remains intact.

As for your gibbering about sound pressure measurements - please don't
insult this group with such tripe. Everyone else on here clearly knows
a great deal more than you.

d

[Misifus[_2_]]

Ray Thomas wrote:
"GregS" wrote in message
...
In article , "David Grant"
wrote:
My understanding (of the sales pitch/marketing ?) of the function of
cones
or spikes was that they were supposed to act as a 'physical diode'..in
other words to allow unwanted vibrations and micro-motion to transfer
from
the speaker cabinet into the thick end of the cone and then down through
its point to a massy, inert body below it (floor, shelf, concrete slab
etc) which would then absorb the vibes and in theory refuse to allow
them
to be reflected back up the spike/cone again ? I don't know how
complete
this diode principle was meant to be, in terms of allowing one way
transmission of kinetic energy only ? Wouldn't that depend on a
gradation
of absorptive materials on the downwards path so that 'reflections' of
energy wouldn't travel back up the cone again ...? So if the cone point
terminated in a full sandbox, for example, that would presumably act as
an
energy-sink. Dunno, that's my shaky (ha !) understanding of the "theory"
anyway.
RT

I studied transmission lines from an electrical engineering standpoint a
few
years ago and I expect this represents the mechanical equivalent. It
should
be possible to minimize vibration reflections at the termination via
impedance matching (where impedance in this case is a complex value based
on
mass, spring, damping).

The diode analogy sounds iffy. The direction of elecron flow can be
controlled using charges but a vibration carries no polarity. I don't
believe an atom of matter has any means with which to determine whether a
vibration came from direction x or direction -x. It would have to
communicate with adjacent members to determine the direction of
propogation,
and then somehow it would have to absorb that energy or transmit it
depending on the case. That doesn't sound like a natural property of
matter.
I suspect someone looked at the spikes one day and made a conclusion
for no good reason. The spikes does go through carpeting and touch the
floor, which
for no other reason keep the speaker from rocking back and forth on the
rug.
I think I have also seen spikes which look more like nails. I would rather
have the speaker on the rug, but the spikes look pretty both on the rug
and
on a wooden floor, except when you try to slide them.

greg

You are obviously far too pragmatic and sensible about resonance physics, so
let me provoke a little controversy by introducing you to the black arts of
Shun Mook, which have been around for many years now. Now let's see...these
should stir the pot sufficiently, at least for the entree course ;-)

http://www.shunmook.com/text1.htm

http://www.shunmook.com/text2.htm and for comprehensive overview
http://www.stereophile.com/features/69/ (10+ pages of followup and
reader's replies too !)

Ray




The sort of thing one tries to avoid stepping on in the pasture.

-Raf

--
Misifus-
Rafael Seibert

Photos: http://www.flickr.com/photos/rafiii
home: http://www.rafandsioux.com

[Misifus[_2_]]

thepaulthomas wrote:
On Dec 9, 1:35 pm, "Arny Krueger" wrote:
"thepaulthomas"
wrote in



On Dec 9, 10:11 am, "Arny Krueger"
wrote:
"Ray Thomas" wrote in message

My understanding (of the sales pitch/marketing ?) of the
function of cones or spikes was that they were supposed
to act as a 'physical diode'..in other words to allow
unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and
then down through its point to a massy, inert body
below it (floor, shelf, concrete slab etc) which would
then absorb the vibes and in theory refuse to allow
them to be reflected back up the spike/cone again ?
However the biggest fallacy is the idea that there will
be significant vibrations of the speaker cabinet.
Does that mean building speaker cabinets of heavier
materials is pointless?
No, but its all a matter of diminishing returns.

Also, if you want a stiff cabinet, after a certain point, additional wood is
better allocated to internal bracing.

OK, gotcha. Thanks, Arny. Now what about things like concrete
cabinets? I have a small pair of Rauna speakers that I like and they
are made of concrete. Even though they are "bookshelf" size speakers
they weigh about 45 pounds each. Would you consider that type of
construction to be way beyond the point of diminishing returns or
would the significantly heavier concrete walls just be similar in
effect to the extra bracing you mentioned?


Seems to me that while the concrete cabinets may be beyond the point of
diminishing returns with regard to cabinet weight, they may well
represent a significant savings in the cost of production.

-Raf

--
Misifus-
Rafael Seibert

Photos: http://www.flickr.com/photos/rafiii
home: http://www.rafandsioux.com