Kalman Rubinson wrote:

....snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

But there's more to it than cone area because Vd also depends on the Xmax
(excursion) of the drivers as well which is a function of both motor and
suspension stroke. Generally speaking, the geometry of a larger basket
typically comes with a bigger motor and more suspension excursion.

So depending on the particular application a pair of 6-inch drivers may
approximate the displacement of a single 10-inch but there's a fair amount of
units that fall somewhat short of that capability.

As mentioned better directivity control and thinner cabinets are the main
advantages. In the former case the possibility of staggering the operating
ranges of multiple drivers and having one positioned close to the floor help
control the 200-300 Hz "floor bounce" common to tower style speakers.

Kalman Rubinson wrote:

....snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

But there's more to it than cone area because Vd also depends on the Xmax
(excursion) of the drivers as well which is a function of both motor and
suspension stroke. Generally speaking, the geometry of a larger basket
typically comes with a bigger motor and more suspension excursion.

So depending on the particular application a pair of 6-inch drivers may
approximate the displacement of a single 10-inch but there's a fair amount of
units that fall somewhat short of that capability.

As mentioned better directivity control and thinner cabinets are the main
advantages. In the former case the possibility of staggering the operating
ranges of multiple drivers and having one positioned close to the floor help
control the 200-300 Hz "floor bounce" common to tower style speakers.

Kalman Rubinson wrote:

....snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

But there's more to it than cone area because Vd also depends on the Xmax
(excursion) of the drivers as well which is a function of both motor and
suspension stroke. Generally speaking, the geometry of a larger basket
typically comes with a bigger motor and more suspension excursion.

So depending on the particular application a pair of 6-inch drivers may
approximate the displacement of a single 10-inch but there's a fair amount of
units that fall somewhat short of that capability.

As mentioned better directivity control and thinner cabinets are the main
advantages. In the former case the possibility of staggering the operating
ranges of multiple drivers and having one positioned close to the floor help
control the 200-300 Hz "floor bounce" common to tower style speakers.

I remember Martin-Logan. Their electrostatics, along with Apogee's
ribbon speakers, were quite cool looking. However, I like to stick
with conventional designs and a conventional budget . Besides, I
think cones are still supposed to be the best when it comes to hard
rock.

If thats main choice buy either JBL's or Cerwin's both are most faithful to
a hard rock sound, check out

JBL E100 or E90's or Cerwin E-715 or E-712

The 4 x Cerwins with a big amp can generate rock venue level sounds at a
price point that is affordable, However your neighbors may never speak to
you again.

I remember Martin-Logan. Their electrostatics, along with Apogee's
ribbon speakers, were quite cool looking. However, I like to stick
with conventional designs and a conventional budget . Besides, I
think cones are still supposed to be the best when it comes to hard
rock.

If thats main choice buy either JBL's or Cerwin's both are most faithful to
a hard rock sound, check out

JBL E100 or E90's or Cerwin E-715 or E-712

The 4 x Cerwins with a big amp can generate rock venue level sounds at a
price point that is affordable, However your neighbors may never speak to
you again.

I remember Martin-Logan. Their electrostatics, along with Apogee's
ribbon speakers, were quite cool looking. However, I like to stick
with conventional designs and a conventional budget . Besides, I
think cones are still supposed to be the best when it comes to hard
rock.

If thats main choice buy either JBL's or Cerwin's both are most faithful to
a hard rock sound, check out

JBL E100 or E90's or Cerwin E-715 or E-712

The 4 x Cerwins with a big amp can generate rock venue level sounds at a
price point that is affordable, However your neighbors may never speak to
you again.

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

On Sun, 07 Dec 2003 21:45:33 GMT, Alan Peterman
wrote:

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches.

Ummm. Make that something like 6.25pi (square the radius, not the
diameter).

A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area,

16pi

and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

I suspect the reason has more to do with the limited bandwidth and the
lower Fs.

Kal

On Sun, 07 Dec 2003 21:45:33 GMT, Alan Peterman
wrote:

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches.

Ummm. Make that something like 6.25pi (square the radius, not the
diameter).

A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area,

16pi

and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

I suspect the reason has more to do with the limited bandwidth and the
lower Fs.

Kal

On Sun, 07 Dec 2003 21:45:33 GMT, Alan Peterman
wrote:

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches.

Ummm. Make that something like 6.25pi (square the radius, not the
diameter).

A 10" drive is around 8-8.5 inches in cone size thus
about 64-72pi area,

16pi

and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

I suspect the reason has more to do with the limited bandwidth and the
lower Fs.

Kal

(StuWelwood) wrote in message ...

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce frequencies BELOW
those which can be heard, i.e., they can only be felt. But I see these puny
little systems that couldn't do a decent job of cleanly reproducing 80 Hz at
any volume that I would call usable being called such.

And often mated with tiny 2" surround speakers that are somehow
supposed to reproduce the rest of the audio spectrum. The resulting
system sounds like something akin to a clock radio with booming bass
.

* Chexxon

(StuWelwood) wrote in message ...

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce frequencies BELOW
those which can be heard, i.e., they can only be felt. But I see these puny
little systems that couldn't do a decent job of cleanly reproducing 80 Hz at
any volume that I would call usable being called such.

And often mated with tiny 2" surround speakers that are somehow
supposed to reproduce the rest of the audio spectrum. The resulting
system sounds like something akin to a clock radio with booming bass
.

* Chexxon

(StuWelwood) wrote in message ...

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce frequencies BELOW
those which can be heard, i.e., they can only be felt. But I see these puny
little systems that couldn't do a decent job of cleanly reproducing 80 Hz at
any volume that I would call usable being called such.

And often mated with tiny 2" surround speakers that are somehow
supposed to reproduce the rest of the audio spectrum. The resulting
system sounds like something akin to a clock radio with booming bass
.

* Chexxon

"chexxon" wrote in message
om...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place?

**B&W were an early(ish) adopter, with the B&W 802, ca. 1983. KEF, with the
104/2, ca. 1984 was there as well. Infinity, with the RS4 and RS5 were
available at around the same time.

And what is the advantage of it,
other than thinner speaker cabinets?

**Narrow cabinets, higher crossover points (very handy, when dealing with
two way designs).

I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me .

**You would really want 2 X 200mm drivers, to equal 1 X 250mm driver.

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

**Not specifically. All things being equal (which they raerely are), the
following is approximately true (WRT cone area):

1 X 170mm driver = 2 X 130mm drivers
1 X 200mm driver = 2 X 170mm drivers.
1 X 250mm driver = 2 X 200mm drivers.
1 X 300mm driver = 2 X 250mm drivers
1 X 350mm driver = 2 X 300mm drivers.

So, you would really want 8 X 170mm (6.5 inch, in American-speak) drivers to
equal 1 X 300mm (12 inch, in American-speak) driver. All things being equal,
of course. The big advantage of using 8 X 170mm drivers, is that they could
be relatively easily crossed over to a dome tweeter. A 300mm driver could
not successfully acheive this.

Or was this
change driven totally by floor-space considerations?

**Partly. Tall enclosures obviate the need for stands to raise the tweeter
to ear height.


Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

**Well, the enclosures you speak of, were available long before 1994 and
even some US manufacturers were building them. The Infinity RS1 dates from
around 1980 (i seem to recall) and used an array OF 200mm drivers.


--
Trevor Wilson
www.rageaudio.com.au

"chexxon" wrote in message
om...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place?

**B&W were an early(ish) adopter, with the B&W 802, ca. 1983. KEF, with the
104/2, ca. 1984 was there as well. Infinity, with the RS4 and RS5 were
available at around the same time.

And what is the advantage of it,
other than thinner speaker cabinets?

**Narrow cabinets, higher crossover points (very handy, when dealing with
two way designs).

I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me .

**You would really want 2 X 200mm drivers, to equal 1 X 250mm driver.

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

**Not specifically. All things being equal (which they raerely are), the
following is approximately true (WRT cone area):

1 X 170mm driver = 2 X 130mm drivers
1 X 200mm driver = 2 X 170mm drivers.
1 X 250mm driver = 2 X 200mm drivers.
1 X 300mm driver = 2 X 250mm drivers
1 X 350mm driver = 2 X 300mm drivers.

So, you would really want 8 X 170mm (6.5 inch, in American-speak) drivers to
equal 1 X 300mm (12 inch, in American-speak) driver. All things being equal,
of course. The big advantage of using 8 X 170mm drivers, is that they could
be relatively easily crossed over to a dome tweeter. A 300mm driver could
not successfully acheive this.

Or was this
change driven totally by floor-space considerations?

**Partly. Tall enclosures obviate the need for stands to raise the tweeter
to ear height.


Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

**Well, the enclosures you speak of, were available long before 1994 and
even some US manufacturers were building them. The Infinity RS1 dates from
around 1980 (i seem to recall) and used an array OF 200mm drivers.


--
Trevor Wilson
www.rageaudio.com.au

"chexxon" wrote in message
om...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place?

**B&W were an early(ish) adopter, with the B&W 802, ca. 1983. KEF, with the
104/2, ca. 1984 was there as well. Infinity, with the RS4 and RS5 were
available at around the same time.

And what is the advantage of it,
other than thinner speaker cabinets?

**Narrow cabinets, higher crossover points (very handy, when dealing with
two way designs).

I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me .

**You would really want 2 X 200mm drivers, to equal 1 X 250mm driver.

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

**Not specifically. All things being equal (which they raerely are), the
following is approximately true (WRT cone area):

1 X 170mm driver = 2 X 130mm drivers
1 X 200mm driver = 2 X 170mm drivers.
1 X 250mm driver = 2 X 200mm drivers.
1 X 300mm driver = 2 X 250mm drivers
1 X 350mm driver = 2 X 300mm drivers.

So, you would really want 8 X 170mm (6.5 inch, in American-speak) drivers to
equal 1 X 300mm (12 inch, in American-speak) driver. All things being equal,
of course. The big advantage of using 8 X 170mm drivers, is that they could
be relatively easily crossed over to a dome tweeter. A 300mm driver could
not successfully acheive this.

Or was this
change driven totally by floor-space considerations?

**Partly. Tall enclosures obviate the need for stands to raise the tweeter
to ear height.


Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

**Well, the enclosures you speak of, were available long before 1994 and
even some US manufacturers were building them. The Infinity RS1 dates from
around 1980 (i seem to recall) and used an array OF 200mm drivers.


--
Trevor Wilson
www.rageaudio.com.au

(Per Stromgren) wrote in message ...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

Then again, that problem must have been licked a long time ago, or we
wouldn't have 3-way speakers to begin with .

* Chexxon

(Per Stromgren) wrote in message ...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

Then again, that problem must have been licked a long time ago, or we
wouldn't have 3-way speakers to begin with .

* Chexxon

(Per Stromgren) wrote in message ...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

Then again, that problem must have been licked a long time ago, or we
wouldn't have 3-way speakers to begin with .

* Chexxon

On Sun, 07 Dec 2003 16:56:33 -0500, Kalman Rubinson wrote:


and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Well I did forget to divide by two for the radius, but it matters not a bit when
doing comparisons of relative cone size. And with "8 inch" drivers having an
effective cone size of 6 inches, that results in a cone area of 9pi so a "12
inch" driver has nearly 3 times the cone area of the 8 inch ones. As I said.

And unless you either use a LARGE corner horn loaded enclosure or a driver with
maximum cone excursion of over 1cm (which is pretty unusual and difficult to
control) there's really no way to get good bass without a driver larger than an
8" one. Which is why I augment the 12" drivers in my Infinity RS 2.5's (which
are driven by a Moscode 600 amp) with a Velodyne CT-150 with a 15" driver.

Oh - and to answer the original question, I remember the first large speaker
system I built, in 1965 was one using 2 8 inch drivers in a slot and tube loaded
enclosure. It was in a Popular Electronics construction article back then. So
the use of multiple smaller drivers dates back to at least the early 60's, if
not further.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

On Sun, 07 Dec 2003 16:56:33 -0500, Kalman Rubinson wrote:


and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Well I did forget to divide by two for the radius, but it matters not a bit when
doing comparisons of relative cone size. And with "8 inch" drivers having an
effective cone size of 6 inches, that results in a cone area of 9pi so a "12
inch" driver has nearly 3 times the cone area of the 8 inch ones. As I said.

And unless you either use a LARGE corner horn loaded enclosure or a driver with
maximum cone excursion of over 1cm (which is pretty unusual and difficult to
control) there's really no way to get good bass without a driver larger than an
8" one. Which is why I augment the 12" drivers in my Infinity RS 2.5's (which
are driven by a Moscode 600 amp) with a Velodyne CT-150 with a 15" driver.

Oh - and to answer the original question, I remember the first large speaker
system I built, in 1965 was one using 2 8 inch drivers in a slot and tube loaded
enclosure. It was in a Popular Electronics construction article back then. So
the use of multiple smaller drivers dates back to at least the early 60's, if
not further.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

On Sun, 07 Dec 2003 16:56:33 -0500, Kalman Rubinson wrote:


and a 12" driver has about a 10" cone, thus 100pi area -

25pi

about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Four 6.5s, mebbe, but more like two 8 inchers.

Well I did forget to divide by two for the radius, but it matters not a bit when
doing comparisons of relative cone size. And with "8 inch" drivers having an
effective cone size of 6 inches, that results in a cone area of 9pi so a "12
inch" driver has nearly 3 times the cone area of the 8 inch ones. As I said.

And unless you either use a LARGE corner horn loaded enclosure or a driver with
maximum cone excursion of over 1cm (which is pretty unusual and difficult to
control) there's really no way to get good bass without a driver larger than an
8" one. Which is why I augment the 12" drivers in my Infinity RS 2.5's (which
are driven by a Moscode 600 amp) with a Velodyne CT-150 with a 15" driver.

Oh - and to answer the original question, I remember the first large speaker
system I built, in 1965 was one using 2 8 inch drivers in a slot and tube loaded
enclosure. It was in a Popular Electronics construction article back then. So
the use of multiple smaller drivers dates back to at least the early 60's, if
not further.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.

Alan Peterman wrote:



On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch
drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single
10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size
thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.


Actually I WAS referencing the driven piston area of the drivers and NOT the
nominal basket size.

Most of the 'rules-of-thumb" for cone area use 1/3 the surround as 'piston' but
IME usually 1/4 may be a better estimate when compared to the actual SPL
generation of a give unit. Thus the ultra-wide surrounds often seen on woofers
(like the Sunfire, supposedly used to enable long stroke) tend to sacrifice
10-15% of true piston area meaning that they must make up even more in
excursion than one might think.

But, the general rule of thumb is 1.5 times the displacement for each basket
size. So a 10-inch has 150% more dispacement than a single 8 and a 12 has 50%
more displacement than a 10. So as a general rule of thumb is that you will in
many cases need 3 eights to make a 12 in real displacement.

Alan Peterman wrote:



On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch
drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single
10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size
thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.


Actually I WAS referencing the driven piston area of the drivers and NOT the
nominal basket size.

Most of the 'rules-of-thumb" for cone area use 1/3 the surround as 'piston' but
IME usually 1/4 may be a better estimate when compared to the actual SPL
generation of a give unit. Thus the ultra-wide surrounds often seen on woofers
(like the Sunfire, supposedly used to enable long stroke) tend to sacrifice
10-15% of true piston area meaning that they must make up even more in
excursion than one might think.

But, the general rule of thumb is 1.5 times the displacement for each basket
size. So a 10-inch has 150% more dispacement than a single 8 and a 12 has 50%
more displacement than a 10. So as a general rule of thumb is that you will in
many cases need 3 eights to make a 12 in real displacement.

Alan Peterman wrote:



On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a 12-inch
drivers.
A pair of 6 or 6.5-inch drivers approximat the piston area of a single
10-inch.

That's a commonly held idea, but it's usually quite wrong because the nominal
speaker size is NOT the diameter of the actual moving cone. On a 6.5" driver
you will usually find the cone is about 5" in diameter, thus the cone area is
about 25pi square inches. A 10" drive is around 8-8.5 inches in cone size
thus
about 64-72pi area, and a 12" driver has about a 10" cone, thus 100pi area -
about the area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to multiple
smaller ones.

---------------------------------------------------------------
Alan Peterman al at scn.rain.com Tigard, OR
As I grow older, the days seem longer and the years seem shorter.


Actually I WAS referencing the driven piston area of the drivers and NOT the
nominal basket size.

Most of the 'rules-of-thumb" for cone area use 1/3 the surround as 'piston' but
IME usually 1/4 may be a better estimate when compared to the actual SPL
generation of a give unit. Thus the ultra-wide surrounds often seen on woofers
(like the Sunfire, supposedly used to enable long stroke) tend to sacrifice
10-15% of true piston area meaning that they must make up even more in
excursion than one might think.

But, the general rule of thumb is 1.5 times the displacement for each basket
size. So a 10-inch has 150% more dispacement than a single 8 and a 12 has 50%
more displacement than a 10. So as a general rule of thumb is that you will in
many cases need 3 eights to make a 12 in real displacement.

(chexxon) wrote in message . com...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place? And what is the advantage of it,
other than thinner speaker cabinets? I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me . Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy? Or was this
change driven totally by floor-space considerations?

Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

* Chexxon


Let me add to the confusion here,

For LOW-frequency reproduction the volume displacement must be
considered an important factor, which is the piston area and the
maximum cone excursion. A quick look at a speaker manufacturers
homepage (I randomly selected Peerless)
gave me these figures:
name Diameter Sd xmax Max vol disp.
WF 165 165 mm (6.5") 130 cm2 4 mm 52 cm3
WF 210 210 mm (8.26") 225 cm2 3.5 mm 78.75 cm3
260 SWR 260 mm (10.2") 310 cm2 9 mm 279 cm3
315 SWR 315 mm (12.4") 520 cm2 9 mm 578 cm3

So, for example we would need 279/52=5.4 WF 165's to acheive the same
volume displacement as one 260 SWR and so on.

Note: The efficiency of four speakers, when mounted close to
oneanother is quadrupled, or + 6dB, compared to a single speaker. But
that is a different thread... :-)

For higher frequencies two factors are important:
1: Above the frequency where the wavelength is on the same order of
magnitude as the driver(s), the sound will start to be directed. This
is true also for the multiple speakers, but the size that is important
is NOT that of the individual drivers, but the whole system. If the
speakers are stacked vertically, there will be more directicity in the
vertical plane than in the horizontal plane.
2: Cone break-up. The mechanical force is applied near the centre of
the cone, and from that point a mechanical wave will propagate out
towards the edges of the cone. If the wavelength of that wave is on
the same order of magnitude as the size of the cone, the cone will no
more move as a rigid piston. This is called "break-up" and will cause
the response curve to "wiggle" above a certain frequency. This
frequency is generally higher for smaller drivers, and is NOT affected
to any large extent of the number of drivers.

(chexxon) wrote in message . com...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place? And what is the advantage of it,
other than thinner speaker cabinets? I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me . Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy? Or was this
change driven totally by floor-space considerations?

Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

* Chexxon


Let me add to the confusion here,

For LOW-frequency reproduction the volume displacement must be
considered an important factor, which is the piston area and the
maximum cone excursion. A quick look at a speaker manufacturers
homepage (I randomly selected Peerless)
gave me these figures:
name Diameter Sd xmax Max vol disp.
WF 165 165 mm (6.5") 130 cm2 4 mm 52 cm3
WF 210 210 mm (8.26") 225 cm2 3.5 mm 78.75 cm3
260 SWR 260 mm (10.2") 310 cm2 9 mm 279 cm3
315 SWR 315 mm (12.4") 520 cm2 9 mm 578 cm3

So, for example we would need 279/52=5.4 WF 165's to acheive the same
volume displacement as one 260 SWR and so on.

Note: The efficiency of four speakers, when mounted close to
oneanother is quadrupled, or + 6dB, compared to a single speaker. But
that is a different thread... :-)

For higher frequencies two factors are important:
1: Above the frequency where the wavelength is on the same order of
magnitude as the driver(s), the sound will start to be directed. This
is true also for the multiple speakers, but the size that is important
is NOT that of the individual drivers, but the whole system. If the
speakers are stacked vertically, there will be more directicity in the
vertical plane than in the horizontal plane.
2: Cone break-up. The mechanical force is applied near the centre of
the cone, and from that point a mechanical wave will propagate out
towards the edges of the cone. If the wavelength of that wave is on
the same order of magnitude as the size of the cone, the cone will no
more move as a rigid piston. This is called "break-up" and will cause
the response curve to "wiggle" above a certain frequency. This
frequency is generally higher for smaller drivers, and is NOT affected
to any large extent of the number of drivers.

(chexxon) wrote in message . com...
It used to be that virtually every floor-standing speaker had a 10" or
12" woofer. Now they all seem to have dual-6's! Out of curiosity,
when did this changeover take place? And what is the advantage of it,
other than thinner speaker cabinets? I'd personally rather have a
3-foot speaker with a 10" than a 4-foot one with a dual-6", but that's
just me . Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy? Or was this
change driven totally by floor-space considerations?

Forgive me if the above questions are stupid, but I haven't been in
the speaker market since 1994, and it seems like a LOT has changed.
And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh well,
can't stop progress !

* Chexxon


Let me add to the confusion here,

For LOW-frequency reproduction the volume displacement must be
considered an important factor, which is the piston area and the
maximum cone excursion. A quick look at a speaker manufacturers
homepage (I randomly selected Peerless)
gave me these figures:
name Diameter Sd xmax Max vol disp.
WF 165 165 mm (6.5") 130 cm2 4 mm 52 cm3
WF 210 210 mm (8.26") 225 cm2 3.5 mm 78.75 cm3
260 SWR 260 mm (10.2") 310 cm2 9 mm 279 cm3
315 SWR 315 mm (12.4") 520 cm2 9 mm 578 cm3

So, for example we would need 279/52=5.4 WF 165's to acheive the same
volume displacement as one 260 SWR and so on.

Note: The efficiency of four speakers, when mounted close to
oneanother is quadrupled, or + 6dB, compared to a single speaker. But
that is a different thread... :-)

For higher frequencies two factors are important:
1: Above the frequency where the wavelength is on the same order of
magnitude as the driver(s), the sound will start to be directed. This
is true also for the multiple speakers, but the size that is important
is NOT that of the individual drivers, but the whole system. If the
speakers are stacked vertically, there will be more directicity in the
vertical plane than in the horizontal plane.
2: Cone break-up. The mechanical force is applied near the centre of
the cone, and from that point a mechanical wave will propagate out
towards the edges of the cone. If the wavelength of that wave is on
the same order of magnitude as the size of the cone, the cone will no
more move as a rigid piston. This is called "break-up" and will cause
the response curve to "wiggle" above a certain frequency. This
frequency is generally higher for smaller drivers, and is NOT affected
to any large extent of the number of drivers.

"StuWelwood" wrote in message


From: "Arny Krueger"
Date: 12/6/2003 4:59 PM Mountain Standard Time
Message-id:

And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh
well, can't stop progress !

The big woofer is still around, but its in a box labeled "subwoofer".

Man, that's the true that nobody seems to want to admit to. My big
system's speaker systems go down to about 25 hz, much like Kal's (and
I can easily distinguish what direction the sound is coming from at
30 Hz).

Regrettably, that suggests that your woofer has audible nonlinear
distortion, or that something in the room is creating spurious responses.
What you report can also be due to a crossover that has a relatively low
slope that lets a lot of higher frequency stuff skate through, like 6 or 12
dB/octave.

Just to be sure that I wasn't hearing some harmonics and
being fooled into thinking they were the fundamental, I measured
their amplitude with a calibration microphone and found them to be
entirely negligible at low volumes.

So what happens when the speakers are operated at high levels?

We also have this myth of "lack of directionality" of low frequencies.

It traces back to listening tests that many people such as myself have done
with low-distortion woofers. I use a Rane MX-22 24dB/octave crossover which
has a variable frequency control on it. Single knob handles both channels,
high and low pass. I also have a subwoofer that is located quite a bit
closer to my listening chair, and way off to the left. At 100 Hz, and 80 Hz
it's easy to locate the subwoofer by ear. At 50 Hz its exceedingly hard to
locate the subwoofer by ear.

The confusion seems to come from the idea that lower frequencies have
more "spread" and less "beaming," which is entirely true. But we must
realize that this omnidirectionality exists only as seem from the
source. Away from the source, the wave fronts still approach the
listener from the direction of the source. They do not appear to come
from all directions at once, reflections aside.

I've never heard it matter, especially at 30 Hz.

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce
frequencies BELOW those which can be heard, i.e., they can only be
felt. But I see these puny little systems that couldn't do a decent
job of cleanly reproducing 80 Hz at any volume that I would call
usable being called such.

Right, I'm with you there. Lots of gear like this is seen in the vicinity of
computers. I think I even own some of it, but I don't take it too seriously.

The consumer has been fooled into thinking
that they have a better system . (After all, "its new.")

Well, they have something that might be better than it would be with no
subwoofer at all!

;-)

In reality, they lost their two woofers and got a single little woofer to
hide
behide the sofa. Do we even want to mention what happens at the
crossover region when you start moving this poorly designed woofer
indiscriminately around the room?

See my former comments.

I suggest that we start to uncover the "subwoofer" myth by calling it
what it really is - a woofer.

Well, it is what it is and what it is can vary a lot.

My main speakers are NHT 2.5i 3-ways, and are IME pretty clean down to 45
Hz. They are claimed to be effective down to 30 Hz. It's amazing the range
of crossover frequencies over which they sound pretty much the same. But,
above 70 Hz or so, its pretty easy to hear where this subwoofer is, and it
isn't in the preferred location for good imaging. But with a crossover at 65
Hz or so, no audible problems.

"StuWelwood" wrote in message


From: "Arny Krueger"
Date: 12/6/2003 4:59 PM Mountain Standard Time
Message-id:

And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh
well, can't stop progress !

The big woofer is still around, but its in a box labeled "subwoofer".

Man, that's the true that nobody seems to want to admit to. My big
system's speaker systems go down to about 25 hz, much like Kal's (and
I can easily distinguish what direction the sound is coming from at
30 Hz).

Regrettably, that suggests that your woofer has audible nonlinear
distortion, or that something in the room is creating spurious responses.
What you report can also be due to a crossover that has a relatively low
slope that lets a lot of higher frequency stuff skate through, like 6 or 12
dB/octave.

Just to be sure that I wasn't hearing some harmonics and
being fooled into thinking they were the fundamental, I measured
their amplitude with a calibration microphone and found them to be
entirely negligible at low volumes.

So what happens when the speakers are operated at high levels?

We also have this myth of "lack of directionality" of low frequencies.

It traces back to listening tests that many people such as myself have done
with low-distortion woofers. I use a Rane MX-22 24dB/octave crossover which
has a variable frequency control on it. Single knob handles both channels,
high and low pass. I also have a subwoofer that is located quite a bit
closer to my listening chair, and way off to the left. At 100 Hz, and 80 Hz
it's easy to locate the subwoofer by ear. At 50 Hz its exceedingly hard to
locate the subwoofer by ear.

The confusion seems to come from the idea that lower frequencies have
more "spread" and less "beaming," which is entirely true. But we must
realize that this omnidirectionality exists only as seem from the
source. Away from the source, the wave fronts still approach the
listener from the direction of the source. They do not appear to come
from all directions at once, reflections aside.

I've never heard it matter, especially at 30 Hz.

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce
frequencies BELOW those which can be heard, i.e., they can only be
felt. But I see these puny little systems that couldn't do a decent
job of cleanly reproducing 80 Hz at any volume that I would call
usable being called such.

Right, I'm with you there. Lots of gear like this is seen in the vicinity of
computers. I think I even own some of it, but I don't take it too seriously.

The consumer has been fooled into thinking
that they have a better system . (After all, "its new.")

Well, they have something that might be better than it would be with no
subwoofer at all!

;-)

In reality, they lost their two woofers and got a single little woofer to
hide
behide the sofa. Do we even want to mention what happens at the
crossover region when you start moving this poorly designed woofer
indiscriminately around the room?

See my former comments.

I suggest that we start to uncover the "subwoofer" myth by calling it
what it really is - a woofer.

Well, it is what it is and what it is can vary a lot.

My main speakers are NHT 2.5i 3-ways, and are IME pretty clean down to 45
Hz. They are claimed to be effective down to 30 Hz. It's amazing the range
of crossover frequencies over which they sound pretty much the same. But,
above 70 Hz or so, its pretty easy to hear where this subwoofer is, and it
isn't in the preferred location for good imaging. But with a crossover at 65
Hz or so, no audible problems.

"StuWelwood" wrote in message


From: "Arny Krueger"
Date: 12/6/2003 4:59 PM Mountain Standard Time
Message-id:

And this particular change really surprises me, since a single big
woofer has a particular sex appeal that two small ones lack. Oh
well, can't stop progress !

The big woofer is still around, but its in a box labeled "subwoofer".

Man, that's the true that nobody seems to want to admit to. My big
system's speaker systems go down to about 25 hz, much like Kal's (and
I can easily distinguish what direction the sound is coming from at
30 Hz).

Regrettably, that suggests that your woofer has audible nonlinear
distortion, or that something in the room is creating spurious responses.
What you report can also be due to a crossover that has a relatively low
slope that lets a lot of higher frequency stuff skate through, like 6 or 12
dB/octave.

Just to be sure that I wasn't hearing some harmonics and
being fooled into thinking they were the fundamental, I measured
their amplitude with a calibration microphone and found them to be
entirely negligible at low volumes.

So what happens when the speakers are operated at high levels?

We also have this myth of "lack of directionality" of low frequencies.

It traces back to listening tests that many people such as myself have done
with low-distortion woofers. I use a Rane MX-22 24dB/octave crossover which
has a variable frequency control on it. Single knob handles both channels,
high and low pass. I also have a subwoofer that is located quite a bit
closer to my listening chair, and way off to the left. At 100 Hz, and 80 Hz
it's easy to locate the subwoofer by ear. At 50 Hz its exceedingly hard to
locate the subwoofer by ear.

The confusion seems to come from the idea that lower frequencies have
more "spread" and less "beaming," which is entirely true. But we must
realize that this omnidirectionality exists only as seem from the
source. Away from the source, the wave fronts still approach the
listener from the direction of the source. They do not appear to come
from all directions at once, reflections aside.

I've never heard it matter, especially at 30 Hz.

Now, as for terminology, my understanding is that the term "subwoofer"
originally meant that the speaker was intended to reproduce
frequencies BELOW those which can be heard, i.e., they can only be
felt. But I see these puny little systems that couldn't do a decent
job of cleanly reproducing 80 Hz at any volume that I would call
usable being called such.

Right, I'm with you there. Lots of gear like this is seen in the vicinity of
computers. I think I even own some of it, but I don't take it too seriously.

The consumer has been fooled into thinking
that they have a better system . (After all, "its new.")

Well, they have something that might be better than it would be with no
subwoofer at all!

;-)

In reality, they lost their two woofers and got a single little woofer to
hide
behide the sofa. Do we even want to mention what happens at the
crossover region when you start moving this poorly designed woofer
indiscriminately around the room?

See my former comments.

I suggest that we start to uncover the "subwoofer" myth by calling it
what it really is - a woofer.

Well, it is what it is and what it is can vary a lot.

My main speakers are NHT 2.5i 3-ways, and are IME pretty clean down to 45
Hz. They are claimed to be effective down to 30 Hz. It's amazing the range
of crossover frequencies over which they sound pretty much the same. But,
above 70 Hz or so, its pretty easy to hear where this subwoofer is, and it
isn't in the preferred location for good imaging. But with a crossover at 65
Hz or so, no audible problems.

"chexxon" wrote in message
om
(Per Stromgren) wrote in message
...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

With small speakers, you loose bass power-handling two ways. First, we all
understand how the cone area goes down with the square of the diameter.
Secondly Xmax has a nasty tendency to decrease with the diameter.

So, all other things being more-or-less equal, bass power-handling goes down
roughly with the cube of the diameter. IOW it takes 8 each 6 inch speakers
to have the power-handling capacity of an otherwise comparable 12 inch
speaker.

XMax tends to go down proportional with the diameter because in the final
analysis, when all other limiting factors are dealt with, it tends to be
limited by angular displacements. IOW you can build a small driver with a
long voice coil, but then the spider and the outer surround become the
limiting factors.

"chexxon" wrote in message
om
(Per Stromgren) wrote in message
...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

With small speakers, you loose bass power-handling two ways. First, we all
understand how the cone area goes down with the square of the diameter.
Secondly Xmax has a nasty tendency to decrease with the diameter.

So, all other things being more-or-less equal, bass power-handling goes down
roughly with the cube of the diameter. IOW it takes 8 each 6 inch speakers
to have the power-handling capacity of an otherwise comparable 12 inch
speaker.

XMax tends to go down proportional with the diameter because in the final
analysis, when all other limiting factors are dealt with, it tends to be
limited by angular displacements. IOW you can build a small driver with a
long voice coil, but then the spider and the outer surround become the
limiting factors.

"chexxon" wrote in message
om
(Per Stromgren) wrote in message
...

Low maximum volume, due to low displacement of the cones. For a given
(set of) driver and frequency, larger displacement means higher sound
volume.

So, all else being equal, I guess that two 6's are still a bit less
than a single 10 . Especially when one considers that the
additional driver adds a layer of complexity to the design. Suppose
that woofer A is a split second behind woofer B? Wouldn't it create
an echo effect?

With small speakers, you loose bass power-handling two ways. First, we all
understand how the cone area goes down with the square of the diameter.
Secondly Xmax has a nasty tendency to decrease with the diameter.

So, all other things being more-or-less equal, bass power-handling goes down
roughly with the cube of the diameter. IOW it takes 8 each 6 inch speakers
to have the power-handling capacity of an otherwise comparable 12 inch
speaker.

XMax tends to go down proportional with the diameter because in the final
analysis, when all other limiting factors are dealt with, it tends to be
limited by angular displacements. IOW you can build a small driver with a
long voice coil, but then the spider and the outer surround become the
limiting factors.

"Alan Peterman" wrote in message

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a
12-inch drivers. A pair of 6 or 6.5-inch drivers approximat the
piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the
nominal speaker size is NOT the diameter of the actual moving cone.
On a 6.5" driver you will usually find the cone is about 5" in
diameter, thus the cone area is about 25pi square inches. A 10"
drive is around 8-8.5 inches in cone size thus about 64-72pi area,
and a 12" driver has about a 10" cone, thus 100pi area - about the
area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to
multiple smaller ones.

Agreed as far as it goes, and BTW Tom knows that, too. He was just using the
word approximate in an extreme way.

Once the voice coil length issues are settled, Xmax tends to be limited by a
narrow surround. A 12" driver with a 1" wide surround loses 1/6 of its
diameter or about 1/3 of its cone area to the surround. However a 6: driver
with a 1" surround loses 1/3 of its diameter or well over 1/2 of its cone
area to the surround. This hurts!

Collections of small drivers also drive up the parts count.

At the other extreme, drivers seem to be less economical to build when they
are larger than 12". This probably relates to tooling costs, among other
things.

At any rate the economic advantages of reduced parts count tend to reverse
themselves, and most REALLY high-capacity subwoofers are built using more
than one driver per speaker whether they are 12s, 15s or 18s.

"Alan Peterman" wrote in message

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a
12-inch drivers. A pair of 6 or 6.5-inch drivers approximat the
piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the
nominal speaker size is NOT the diameter of the actual moving cone.
On a 6.5" driver you will usually find the cone is about 5" in
diameter, thus the cone area is about 25pi square inches. A 10"
drive is around 8-8.5 inches in cone size thus about 64-72pi area,
and a 12" driver has about a 10" cone, thus 100pi area - about the
area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to
multiple smaller ones.

Agreed as far as it goes, and BTW Tom knows that, too. He was just using the
word approximate in an extreme way.

Once the voice coil length issues are settled, Xmax tends to be limited by a
narrow surround. A 12" driver with a 1" wide surround loses 1/6 of its
diameter or about 1/3 of its cone area to the surround. However a 6: driver
with a 1" surround loses 1/3 of its diameter or well over 1/2 of its cone
area to the surround. This hurts!

Collections of small drivers also drive up the parts count.

At the other extreme, drivers seem to be less economical to build when they
are larger than 12". This probably relates to tooling costs, among other
things.

At any rate the economic advantages of reduced parts count tend to reverse
themselves, and most REALLY high-capacity subwoofers are built using more
than one driver per speaker whether they are 12s, 15s or 18s.

"Alan Peterman" wrote in message

On 07 Dec 2003 20:26:28 GMT, (Nousaine) wrote:

Kalman Rubinson wrote:

...snip to content ......

Do two 6" drivers have the same bass output as a single
12", but with greater control, and thus more accuracy?

Its a question of the total cone area assuming adequate driving
motors.

Two 8-inch drivers generally approximate the piston area of a
12-inch drivers. A pair of 6 or 6.5-inch drivers approximat the
piston area of a single 10-inch.

That's a commonly held idea, but it's usually quite wrong because the
nominal speaker size is NOT the diameter of the actual moving cone.
On a 6.5" driver you will usually find the cone is about 5" in
diameter, thus the cone area is about 25pi square inches. A 10"
drive is around 8-8.5 inches in cone size thus about 64-72pi area,
and a 12" driver has about a 10" cone, thus 100pi area - about the
area of FOUR 6.5 inch drivers! Or about 3 "8 inch" drivers.

Which is why most subwoofers have ONE large driver as opposed to
multiple smaller ones.

Agreed as far as it goes, and BTW Tom knows that, too. He was just using the
word approximate in an extreme way.

Once the voice coil length issues are settled, Xmax tends to be limited by a
narrow surround. A 12" driver with a 1" wide surround loses 1/6 of its
diameter or about 1/3 of its cone area to the surround. However a 6: driver
with a 1" surround loses 1/3 of its diameter or well over 1/2 of its cone
area to the surround. This hurts!

Collections of small drivers also drive up the parts count.

At the other extreme, drivers seem to be less economical to build when they
are larger than 12". This probably relates to tooling costs, among other
things.

At any rate the economic advantages of reduced parts count tend to reverse
themselves, and most REALLY high-capacity subwoofers are built using more
than one driver per speaker whether they are 12s, 15s or 18s.

Alan Peterman wrote in message . ..

And unless you either use a LARGE corner horn loaded enclosure or a driver with
maximum cone excursion of over 1cm (which is pretty unusual and difficult to
control) there's really no way to get good bass without a driver larger than an

In other words, for good bass one needs either A) a good subwoofer, B)
a full-range speaker with a 8" woofer or greater, or C) a speaker with
small woofers coupled with an exotic design.

So
the use of multiple smaller drivers dates back to at least the early 60's, if
not further.

I know that the idea isn't new since they had dual-woofers in the
early 90's as well. I was just wondering when they became dominant.
You see, I've just woken up from an audio slumber that began in 1995,
so I've missed a lot .

* Chexxon