Suggest 8" Woofers, Please

[hank alrich]

What are the baddest ass mini wooferesque cone drivers of the 8"
persuasion?

(Yes, I realize size matters. But this is about 8" speakers.)

--
ha

[Jay-AtlDigi]

In article >,
(hank alrich) wrote:

> What are the baddest ass mini wooferesque cone drivers of the 8"
> persuasion?
>
> (Yes, I realize size matters. But this is about 8" speakers.)
>
> --
> ha

I like woofers from Volt.
--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com

[Jay-AtlDigi]

In article >,
(hank alrich) wrote:

> What are the baddest ass mini wooferesque cone drivers of the 8"
> persuasion?
>
> (Yes, I realize size matters. But this is about 8" speakers.)
>
> --
> ha

I like woofers from Volt.
--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com

[Arny Krueger]

hank alrich wrote:
> What are the baddest ass mini wooferesque cone drivers of the 8"
> persuasion?

> (Yes, I realize size matters. But this is about 8" speakers.)

Woofer performance is ultimately defined by linear cone motion and diaphragm
size. You've specified the diaphragm size, so the only thing left is to find
a woofer that can move that diaphragm over the maximum distance with low
distortion. The *magic number* is called Xmax.

Here is an interesting comparison:

JL Audio 8W7-3 Xmax 19 mm
http://www.jlaudio.com/subwoofers/pdfs/8W7_MAN.pdf

Volt B220.3 Xmax 5.5 mm
http://www.voltloudspeakers.co.uk/Loudspeakers/Studio_Range/B220_2/body_b220_2.html

[Arny Krueger]

hank alrich wrote:
> What are the baddest ass mini wooferesque cone drivers of the 8"
> persuasion?

> (Yes, I realize size matters. But this is about 8" speakers.)

Woofer performance is ultimately defined by linear cone motion and diaphragm
size. You've specified the diaphragm size, so the only thing left is to find
a woofer that can move that diaphragm over the maximum distance with low
distortion. The *magic number* is called Xmax.

Here is an interesting comparison:

JL Audio 8W7-3 Xmax 19 mm
http://www.jlaudio.com/subwoofers/pdfs/8W7_MAN.pdf

Volt B220.3 Xmax 5.5 mm
http://www.voltloudspeakers.co.uk/Loudspeakers/Studio_Range/B220_2/body_b220_2.html

[Scott Dorsey]

hank alrich > wrote:
>What are the baddest ass mini wooferesque cone drivers of the 8"
>persuasion?
>
>(Yes, I realize size matters. But this is about 8" speakers.)

I think Aura/Seismic makes an 8" driver, and if so I bet it has a longer
Xmax than anything else around. If badass means longest Xmax and not
lowest Fs, it's the way to go.

NHT makes a 10" driver with an outrageously low Fs, which isn't THAT much
larger, if low Fs is your notion of badass.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

hank alrich > wrote:
>What are the baddest ass mini wooferesque cone drivers of the 8"
>persuasion?
>
>(Yes, I realize size matters. But this is about 8" speakers.)

I think Aura/Seismic makes an 8" driver, and if so I bet it has a longer
Xmax than anything else around. If badass means longest Xmax and not
lowest Fs, it's the way to go.

NHT makes a 10" driver with an outrageously low Fs, which isn't THAT much
larger, if low Fs is your notion of badass.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Kuschel]

>
>What are the baddest ass mini wooferesque cone drivers of the 8"
>persuasion?
>
>(Yes, I realize size matters. But this is about 8" speakers.)
>
>--
>ha
>
>

I don't know about the baddest, but I have a Velodyne 8" in my home theatre
system.

600 Watts RMS amplifier and 28 Hz low frequency. Absolutely shakes the house.

Coming from the bigger is better philosophy of the '60's, I couldn't believe
it.

Richard H. Kuschel
"I canna change the law of physics."-----Scotty

[Richard Kuschel]

>
>What are the baddest ass mini wooferesque cone drivers of the 8"
>persuasion?
>
>(Yes, I realize size matters. But this is about 8" speakers.)
>
>--
>ha
>
>

I don't know about the baddest, but I have a Velodyne 8" in my home theatre
system.

600 Watts RMS amplifier and 28 Hz low frequency. Absolutely shakes the house.

Coming from the bigger is better philosophy of the '60's, I couldn't believe
it.

Richard H. Kuschel
"I canna change the law of physics."-----Scotty

[Arny Krueger]

Scott Dorsey wrote:

> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
> much larger, if low Fs is your notion of badass.

Making a woofer with an outrageously low FS is essentially a matter of
adding moving mass, and thus also sacrificing efficiency above the
mass-loaded range.

It seems like most designers of new systems have recognized that Xmax is the
true measure of ultimate woofer performance. The laws of physics tend to
support this approach.

Most of the newest designs feature a large-Xmax driver, often in an
outrageously small enclosure. This drives the fundamental system resonance
up to someplace in the 50-100 Hz range, which unassisted, results in pretty
lame-sounding acoustical performance. Equalization is then used to obtain
the desired bass response.

This methodology is based on the idea that amplifier power is cheap, good,
and plentiful. It's not for most people who want a vacuum-tube powered
subwoofer!

[Arny Krueger]

Scott Dorsey wrote:

> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
> much larger, if low Fs is your notion of badass.

Making a woofer with an outrageously low FS is essentially a matter of
adding moving mass, and thus also sacrificing efficiency above the
mass-loaded range.

It seems like most designers of new systems have recognized that Xmax is the
true measure of ultimate woofer performance. The laws of physics tend to
support this approach.

Most of the newest designs feature a large-Xmax driver, often in an
outrageously small enclosure. This drives the fundamental system resonance
up to someplace in the 50-100 Hz range, which unassisted, results in pretty
lame-sounding acoustical performance. Equalization is then used to obtain
the desired bass response.

This methodology is based on the idea that amplifier power is cheap, good,
and plentiful. It's not for most people who want a vacuum-tube powered
subwoofer!

[Scott Dorsey]

Arny Krueger > wrote:
>Scott Dorsey wrote:
>
>> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
>> much larger, if low Fs is your notion of badass.
>
>Making a woofer with an outrageously low FS is essentially a matter of
>adding moving mass, and thus also sacrificing efficiency above the
>mass-loaded range.

Pretty much. This is fine.

>It seems like most designers of new systems have recognized that Xmax is the
>true measure of ultimate woofer performance. The laws of physics tend to
>support this approach.

Well, what do you want? Do you want lots and lots of bass, or do you want
a little bit of very deep bass? It's true that to some extent you can trade
the two off but often at the expense of distortion.

>Most of the newest designs feature a large-Xmax driver, often in an
>outrageously small enclosure. This drives the fundamental system resonance
>up to someplace in the 50-100 Hz range, which unassisted, results in pretty
>lame-sounding acoustical performance. Equalization is then used to obtain
>the desired bass response.

Sadly in a lot of cases the linearity also suffers. Some folks (like Velodyne)
have compensated for this by using accelerometer or position feedback.

>This methodology is based on the idea that amplifier power is cheap, good,
>and plentiful. It's not for most people who want a vacuum-tube powered
>subwoofer!

Again, do you want deep bass, loud bass, or linear bass? For studio use,
I'll take deep and linear over loud. For theatre sound use, I'll take loud
over deep or linear.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Arny Krueger > wrote:
>Scott Dorsey wrote:
>
>> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
>> much larger, if low Fs is your notion of badass.
>
>Making a woofer with an outrageously low FS is essentially a matter of
>adding moving mass, and thus also sacrificing efficiency above the
>mass-loaded range.

Pretty much. This is fine.

>It seems like most designers of new systems have recognized that Xmax is the
>true measure of ultimate woofer performance. The laws of physics tend to
>support this approach.

Well, what do you want? Do you want lots and lots of bass, or do you want
a little bit of very deep bass? It's true that to some extent you can trade
the two off but often at the expense of distortion.

>Most of the newest designs feature a large-Xmax driver, often in an
>outrageously small enclosure. This drives the fundamental system resonance
>up to someplace in the 50-100 Hz range, which unassisted, results in pretty
>lame-sounding acoustical performance. Equalization is then used to obtain
>the desired bass response.

Sadly in a lot of cases the linearity also suffers. Some folks (like Velodyne)
have compensated for this by using accelerometer or position feedback.

>This methodology is based on the idea that amplifier power is cheap, good,
>and plentiful. It's not for most people who want a vacuum-tube powered
>subwoofer!

Again, do you want deep bass, loud bass, or linear bass? For studio use,
I'll take deep and linear over loud. For theatre sound use, I'll take loud
over deep or linear.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul Stamler]

First question: What is the intended application, at what volume level, with
what amplifier driving it?

Peace,
Paul

[Paul Stamler]

First question: What is the intended application, at what volume level, with
what amplifier driving it?

Peace,
Paul

[Arny Krueger]

Scott Dorsey wrote:
> Arny Krueger > wrote:
>> Scott Dorsey wrote:
>>
>>> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
>>> much larger, if low Fs is your notion of badass.
>>
>> Making a woofer with an outrageously low FS is essentially a matter
>> of adding moving mass, and thus also sacrificing efficiency above the
>> mass-loaded range.
>
> Pretty much. This is fine.

>> It seems like most designers of new systems have recognized that
>> Xmax is the true measure of ultimate woofer performance. The laws of
>> physics tend to support this approach.

> Well, what do you want? Do you want lots and lots of bass, or do you
> want a little bit of very deep bass?

It would appear that subject to the limitations of Xmax and cone area,
driver efficiency and amplifier power, you can have both.

> It's true that to some extent
> you can trade the two off but often at the expense of distortion.

Xmax is related to linear operation of the speaker driver.

>> Most of the newest designs feature a large-Xmax driver, often in an
>> outrageously small enclosure. This drives the fundamental system
>> resonance up to someplace in the 50-100 Hz range, which unassisted,
>> results in pretty lame-sounding acoustical performance. Equalization
>> is then used to obtain the desired bass response.

> Sadly in a lot of cases the linearity also suffers. Some folks (like
> Velodyne) have compensated for this by using accelerometer or
> position feedback.

It's possible to design a drivers that aresimply linear enough, without
adding feedback.

>> This methodology is based on the idea that amplifier power is cheap,
>> good, and plentiful. It's not for most people who want a vacuum-tube
>> powered subwoofer!

> Again, do you want deep bass, loud bass, or linear bass?

You can have both, but Xmax and cone area set the ultimate practical limit.

> For studio use, I'll take deep and linear over loud.

Small enclosure designs can provide this.

> For theatre sound use, I'll take loud over deep or linear.

If maximum loudness and deep bass are desired, then large enclosures and
drivers to match are indicated. However, Xmax and cone area still set the
ultimate limit to clean and deep.

[Arny Krueger]

Scott Dorsey wrote:
> Arny Krueger > wrote:
>> Scott Dorsey wrote:
>>
>>> NHT makes a 10" driver with an outrageously low Fs, which isn't THAT
>>> much larger, if low Fs is your notion of badass.
>>
>> Making a woofer with an outrageously low FS is essentially a matter
>> of adding moving mass, and thus also sacrificing efficiency above the
>> mass-loaded range.
>
> Pretty much. This is fine.

>> It seems like most designers of new systems have recognized that
>> Xmax is the true measure of ultimate woofer performance. The laws of
>> physics tend to support this approach.

> Well, what do you want? Do you want lots and lots of bass, or do you
> want a little bit of very deep bass?

It would appear that subject to the limitations of Xmax and cone area,
driver efficiency and amplifier power, you can have both.

> It's true that to some extent
> you can trade the two off but often at the expense of distortion.

Xmax is related to linear operation of the speaker driver.

>> Most of the newest designs feature a large-Xmax driver, often in an
>> outrageously small enclosure. This drives the fundamental system
>> resonance up to someplace in the 50-100 Hz range, which unassisted,
>> results in pretty lame-sounding acoustical performance. Equalization
>> is then used to obtain the desired bass response.

> Sadly in a lot of cases the linearity also suffers. Some folks (like
> Velodyne) have compensated for this by using accelerometer or
> position feedback.

It's possible to design a drivers that aresimply linear enough, without
adding feedback.

>> This methodology is based on the idea that amplifier power is cheap,
>> good, and plentiful. It's not for most people who want a vacuum-tube
>> powered subwoofer!

> Again, do you want deep bass, loud bass, or linear bass?

You can have both, but Xmax and cone area set the ultimate practical limit.

> For studio use, I'll take deep and linear over loud.

Small enclosure designs can provide this.

> For theatre sound use, I'll take loud over deep or linear.

If maximum loudness and deep bass are desired, then large enclosures and
drivers to match are indicated. However, Xmax and cone area still set the
ultimate limit to clean and deep.

[Scott Dorsey]

Arny Krueger > wrote:
>
>Xmax is related to linear operation of the speaker driver.

NO! Xmax is related to the total end-to-end operation. Very few drivers
will be linear across the entire throw, because it's difficult to make the
magnetic flux even enough that it's the same in the coil across the entire
throw. I can name some drivers that are acceptably linear only for a very
small fraction of the rated Xmax, and that's without even thinking about cone
breakup issues, just monotonicity.

Run a 20 Hz signal through typical systems and you will hear plenty of
harmonics.

>> Sadly in a lot of cases the linearity also suffers. Some folks (like
>> Velodyne) have compensated for this by using accelerometer or
>> position feedback.
>
>It's possible to design a drivers that aresimply linear enough, without
>adding feedback.

Servodrive has managed this, but I haven't seen anyone else do it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Arny Krueger > wrote:
>
>Xmax is related to linear operation of the speaker driver.

NO! Xmax is related to the total end-to-end operation. Very few drivers
will be linear across the entire throw, because it's difficult to make the
magnetic flux even enough that it's the same in the coil across the entire
throw. I can name some drivers that are acceptably linear only for a very
small fraction of the rated Xmax, and that's without even thinking about cone
breakup issues, just monotonicity.

Run a 20 Hz signal through typical systems and you will hear plenty of
harmonics.

>> Sadly in a lot of cases the linearity also suffers. Some folks (like
>> Velodyne) have compensated for this by using accelerometer or
>> position feedback.
>
>It's possible to design a drivers that aresimply linear enough, without
>adding feedback.

Servodrive has managed this, but I haven't seen anyone else do it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

Scott Dorsey wrote:
> Arny Krueger > wrote:
>>
>> Xmax is related to linear operation of the speaker driver.
>
> NO! Xmax is related to the total end-to-end operation.

Sorry man, but I didn't make the rules and neither did you. Xmax implies a
certain level of linearity.

Total end-to-end operation is known as Xsus.

> Very few
> drivers will be linear across the entire throw, because it's
> difficult to make the magnetic flux even enough that it's the same in
> the coil across the entire throw.

Speaker manufacturers pay people the big bucks to design equipment that does
this.

> I can name some drivers that are
> acceptably linear only for a very small fraction of the rated Xmax,

Then, the vendor who gave the Xmax spec is basically lying with his rating.

Here's an example of SOTA set of definitions for common woofer parameters:

http://www.diysubwoofers.org/misc/dumax/dumax.htm

Note the inclusion of the word "linear" in the definition of Xmax.

Now, check out this not too-recent AES standards committee document,
discussing a forthcoming formal definition for Xmax:

http://www.aes.org/standards/b_comments/comments-reaffirm-aes2.cfm

"Xmax is the voice-coil peak displacement at which the maximal value of
either the total harmonic distortion dt or the 2nd order modulation
distortion d2 or the 3rd-order modulation distortion d3 in the radiated
sound pressure is equal to a defined threshold d. The driver is excited by
the linear superposition of a first tone at the resonance frequency f1=fs
and a second tone f2=8.5 fs with an amplitude ratio of 4:1. The total
harmonic distortion dt assesses the harmonics of f1 and the modulation
distortion d2 and d3 are measured according to IEC 60268. It is recommended
to operate the driver in a baffle (half-space), to measure the sound
pressure in the near field and to use the threshold d=10 %. Manufacturer
shall state Xmax, the dominant type of distortion (dt, d2 or d3) and the
value of the threshold d used."

Bottom line, there's nothing wrong being a little less than
perfectly-informed, and thinking that Xmax doesn't include a notion of
linearity. This would be due to not being aware of these fairly recent
developments. Neverhteless, it seems quite clear that a modern understanding
of Xmax includes a strong notion of linearity. We are clearly on the brink
of a formal definition of Xmax that includes strong wording relating to
linearity.

I am informed that SOTA woofer driver suppliers such as JL Audio rate Xmax
using a criteria that includes linerity.

In the industry today, many well-iniformed people use the term Xmax to mean
linear stroke. The negotiations that remain, relate to exactly what is meant
by linear. There seems to be no remaining controversy among the more
informed segments of the industry, over the fact that Xmax relates to linear
stroke.

> and that's without even thinking about cone breakup issues, just
monotonicity.

Cone breakup is not relevant to this discussion because this is a discussion
of "baddest ass" woofers. A "baddest ass" system would not operate a woofer
in a range where its cone is breaking up.

Xmax is clearly relevent to this discussion. While AFAIK there is no
formalized international standard definition of Xmax, widely-used interim
and de-facto standards have included a strong notion of linearity. Early
proponents of the Xmax spec have been the Dumax and Kippel driver testing
groups. Both clearly rate woofers based on linear stroke. Google finds over
390 unique instances of the exact phrase "linear xmax" and 190 of "xmax
linear".


> Run a 20 Hz signal through typical systems and you will hear plenty of
> harmonics.

Who said anything about a typical system? If you'll recollect the OP, the
question was about "baddest ass" 8" drivers. "Baddest ass" clearly does not
mean the same as typical.

>>> Sadly in a lot of cases the linearity also suffers. Some folks
>>> (like Velodyne) have compensated for this by using accelerometer or
>>> position feedback.

>> It's possible to design a drivers that aresimply linear enough,
>> without adding feedback.

> Servodrive has managed this, but I haven't seen anyone else do it.

Apparently Scott, you need to take another look at some modern high
performance woofers.

[Arny Krueger]

Scott Dorsey wrote:
> Arny Krueger > wrote:
>>
>> Xmax is related to linear operation of the speaker driver.
>
> NO! Xmax is related to the total end-to-end operation.

Sorry man, but I didn't make the rules and neither did you. Xmax implies a
certain level of linearity.

Total end-to-end operation is known as Xsus.

> Very few
> drivers will be linear across the entire throw, because it's
> difficult to make the magnetic flux even enough that it's the same in
> the coil across the entire throw.

Speaker manufacturers pay people the big bucks to design equipment that does
this.

> I can name some drivers that are
> acceptably linear only for a very small fraction of the rated Xmax,

Then, the vendor who gave the Xmax spec is basically lying with his rating.

Here's an example of SOTA set of definitions for common woofer parameters:

http://www.diysubwoofers.org/misc/dumax/dumax.htm

Note the inclusion of the word "linear" in the definition of Xmax.

Now, check out this not too-recent AES standards committee document,
discussing a forthcoming formal definition for Xmax:

http://www.aes.org/standards/b_comments/comments-reaffirm-aes2.cfm

"Xmax is the voice-coil peak displacement at which the maximal value of
either the total harmonic distortion dt or the 2nd order modulation
distortion d2 or the 3rd-order modulation distortion d3 in the radiated
sound pressure is equal to a defined threshold d. The driver is excited by
the linear superposition of a first tone at the resonance frequency f1=fs
and a second tone f2=8.5 fs with an amplitude ratio of 4:1. The total
harmonic distortion dt assesses the harmonics of f1 and the modulation
distortion d2 and d3 are measured according to IEC 60268. It is recommended
to operate the driver in a baffle (half-space), to measure the sound
pressure in the near field and to use the threshold d=10 %. Manufacturer
shall state Xmax, the dominant type of distortion (dt, d2 or d3) and the
value of the threshold d used."

Bottom line, there's nothing wrong being a little less than
perfectly-informed, and thinking that Xmax doesn't include a notion of
linearity. This would be due to not being aware of these fairly recent
developments. Neverhteless, it seems quite clear that a modern understanding
of Xmax includes a strong notion of linearity. We are clearly on the brink
of a formal definition of Xmax that includes strong wording relating to
linearity.

I am informed that SOTA woofer driver suppliers such as JL Audio rate Xmax
using a criteria that includes linerity.

In the industry today, many well-iniformed people use the term Xmax to mean
linear stroke. The negotiations that remain, relate to exactly what is meant
by linear. There seems to be no remaining controversy among the more
informed segments of the industry, over the fact that Xmax relates to linear
stroke.

> and that's without even thinking about cone breakup issues, just
monotonicity.

Cone breakup is not relevant to this discussion because this is a discussion
of "baddest ass" woofers. A "baddest ass" system would not operate a woofer
in a range where its cone is breaking up.

Xmax is clearly relevent to this discussion. While AFAIK there is no
formalized international standard definition of Xmax, widely-used interim
and de-facto standards have included a strong notion of linearity. Early
proponents of the Xmax spec have been the Dumax and Kippel driver testing
groups. Both clearly rate woofers based on linear stroke. Google finds over
390 unique instances of the exact phrase "linear xmax" and 190 of "xmax
linear".


> Run a 20 Hz signal through typical systems and you will hear plenty of
> harmonics.

Who said anything about a typical system? If you'll recollect the OP, the
question was about "baddest ass" 8" drivers. "Baddest ass" clearly does not
mean the same as typical.

>>> Sadly in a lot of cases the linearity also suffers. Some folks
>>> (like Velodyne) have compensated for this by using accelerometer or
>>> position feedback.

>> It's possible to design a drivers that aresimply linear enough,
>> without adding feedback.

> Servodrive has managed this, but I haven't seen anyone else do it.

Apparently Scott, you need to take another look at some modern high
performance woofers.

[Bob Cain]

Arny Krueger wrote:

> hank alrich wrote:
>
>>What are the baddest ass mini wooferesque cone drivers of the 8"
>>persuasion?
>
>
>>(Yes, I realize size matters. But this is about 8" speakers.)
>
>
> Woofer performance is ultimately defined by linear cone motion and diaphragm
> size. You've specified the diaphragm size, so the only thing left is to find
> a woofer that can move that diaphragm over the maximum distance with low
> distortion. The *magic number* is called Xmax.

Arny, can't you somewhat ameliorate the need for large
linear Xmax with a passive port/radiator type enclosure. I
notice that the excursion of the LF driver on my HR824's
seems a lot lower than one would expect when it gets down
there.

The electronics hides the passive radiator but I'll bet
that's where the excursion is and all you need worry about
then is a linear compliance which should be much easier than
a long throw linear magnetic circuit.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Arny Krueger wrote:

> hank alrich wrote:
>
>>What are the baddest ass mini wooferesque cone drivers of the 8"
>>persuasion?
>
>
>>(Yes, I realize size matters. But this is about 8" speakers.)
>
>
> Woofer performance is ultimately defined by linear cone motion and diaphragm
> size. You've specified the diaphragm size, so the only thing left is to find
> a woofer that can move that diaphragm over the maximum distance with low
> distortion. The *magic number* is called Xmax.

Arny, can't you somewhat ameliorate the need for large
linear Xmax with a passive port/radiator type enclosure. I
notice that the excursion of the LF driver on my HR824's
seems a lot lower than one would expect when it gets down
there.

The electronics hides the passive radiator but I'll bet
that's where the excursion is and all you need worry about
then is a linear compliance which should be much easier than
a long throw linear magnetic circuit.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Arny Krueger]

Bob Cain wrote:
> Arny Krueger wrote:
>
>> hank alrich wrote:
>>
>>> What are the baddest ass mini wooferesque cone drivers of the 8"
>>> persuasion?
>>
>>
>>> (Yes, I realize size matters. But this is about 8" speakers.)

>> Woofer performance is ultimately defined by linear cone motion and
>> diaphragm size. You've specified the diaphragm size, so the only
>> thing left is to find a woofer that can move that diaphragm over the
>> maximum distance with low distortion. The *magic number* is called
>> Xmax.

> Arny, can't you somewhat ameliorate the need for large
> linear Xmax with a passive port/radiator type enclosure.

All other things being equal, the large Xmax driver still outperforms the
one with less Xmax. Comparing Xmax requirements for vented and sealed boxes
gives me headaches because of the vastly different trade-offs. For example,
the driver Xmax requirements become extreme for the vented box when you go
much below the port tuning frequency. OTOH at the port frequency, the Xmax
requirements for the driver are about zero.

> I notice that the excursion of the LF driver on my HR824's
> seems a lot lower than one would expect when it gets down
> there.

The HR824 is driven by a carefully filtered signal, which tends to keep
displacement within reason at low frequencies.

> The electronics hides the passive radiator but I'll bet
> that's where the excursion is and all you need worry about
> then is a linear compliance which should be much easier than
> a long throw linear magnetic circuit.

At the vent tuning frequency the driver hardly moves and air flow in the
vent or motion of the passive radiator are way up there. However, as you go
down from there, the situation changes pretty rapidly.

[Arny Krueger]

Bob Cain wrote:
> Arny Krueger wrote:
>
>> hank alrich wrote:
>>
>>> What are the baddest ass mini wooferesque cone drivers of the 8"
>>> persuasion?
>>
>>
>>> (Yes, I realize size matters. But this is about 8" speakers.)

>> Woofer performance is ultimately defined by linear cone motion and
>> diaphragm size. You've specified the diaphragm size, so the only
>> thing left is to find a woofer that can move that diaphragm over the
>> maximum distance with low distortion. The *magic number* is called
>> Xmax.

> Arny, can't you somewhat ameliorate the need for large
> linear Xmax with a passive port/radiator type enclosure.

All other things being equal, the large Xmax driver still outperforms the
one with less Xmax. Comparing Xmax requirements for vented and sealed boxes
gives me headaches because of the vastly different trade-offs. For example,
the driver Xmax requirements become extreme for the vented box when you go
much below the port tuning frequency. OTOH at the port frequency, the Xmax
requirements for the driver are about zero.

> I notice that the excursion of the LF driver on my HR824's
> seems a lot lower than one would expect when it gets down
> there.

The HR824 is driven by a carefully filtered signal, which tends to keep
displacement within reason at low frequencies.

> The electronics hides the passive radiator but I'll bet
> that's where the excursion is and all you need worry about
> then is a linear compliance which should be much easier than
> a long throw linear magnetic circuit.

At the vent tuning frequency the driver hardly moves and air flow in the
vent or motion of the passive radiator are way up there. However, as you go
down from there, the situation changes pretty rapidly.

[Scott Dorsey]

Arny Krueger > wrote:
>
>Bottom line, there's nothing wrong being a little less than
>perfectly-informed, and thinking that Xmax doesn't include a notion of
>linearity. This would be due to not being aware of these fairly recent
>developments. Neverhteless, it seems quite clear that a modern understanding
>of Xmax includes a strong notion of linearity. We are clearly on the brink
>of a formal definition of Xmax that includes strong wording relating to
>linearity.

I'll buy that, and I'll be delighted to see the AES standard actually get
finalized on the subject.

But if you are gonna believe the manufacturer's numbers, you should be very
wary about linearity across the range.

>Cone breakup is not relevant to this discussion because this is a discussion
>of "baddest ass" woofers. A "baddest ass" system would not operate a woofer
>in a range where its cone is breaking up.

Again, I'm still looking for a definition of badass, and whether low end
corner, low end distortion, or low end level is most important.

>Who said anything about a typical system? If you'll recollect the OP, the
>question was about "baddest ass" 8" drivers. "Baddest ass" clearly does not
>mean the same as typical.

Baddest ass could mean extremely high levels with plenty of distortion.
Certainly in car audio circles it seems to.

>>>> Sadly in a lot of cases the linearity also suffers. Some folks
>>>> (like Velodyne) have compensated for this by using accelerometer or
>>>> position feedback.
>
>>> It's possible to design a drivers that aresimply linear enough,
>>> without adding feedback.
>
>> Servodrive has managed this, but I haven't seen anyone else do it.
>
>Apparently Scott, you need to take another look at some modern high
>performance woofers.

Well, I've got one of the Auras on the bench right now. And it's okay,
but it still has way more driver distortion at 20 Hz than my midrange
system has at 1 KHz. And that's not linear enough for a lot of things
(although it's great for portable film systems which is what I am
probably using it for).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Arny Krueger > wrote:
>
>Bottom line, there's nothing wrong being a little less than
>perfectly-informed, and thinking that Xmax doesn't include a notion of
>linearity. This would be due to not being aware of these fairly recent
>developments. Neverhteless, it seems quite clear that a modern understanding
>of Xmax includes a strong notion of linearity. We are clearly on the brink
>of a formal definition of Xmax that includes strong wording relating to
>linearity.

I'll buy that, and I'll be delighted to see the AES standard actually get
finalized on the subject.

But if you are gonna believe the manufacturer's numbers, you should be very
wary about linearity across the range.

>Cone breakup is not relevant to this discussion because this is a discussion
>of "baddest ass" woofers. A "baddest ass" system would not operate a woofer
>in a range where its cone is breaking up.

Again, I'm still looking for a definition of badass, and whether low end
corner, low end distortion, or low end level is most important.

>Who said anything about a typical system? If you'll recollect the OP, the
>question was about "baddest ass" 8" drivers. "Baddest ass" clearly does not
>mean the same as typical.

Baddest ass could mean extremely high levels with plenty of distortion.
Certainly in car audio circles it seems to.

>>>> Sadly in a lot of cases the linearity also suffers. Some folks
>>>> (like Velodyne) have compensated for this by using accelerometer or
>>>> position feedback.
>
>>> It's possible to design a drivers that aresimply linear enough,
>>> without adding feedback.
>
>> Servodrive has managed this, but I haven't seen anyone else do it.
>
>Apparently Scott, you need to take another look at some modern high
>performance woofers.

Well, I've got one of the Auras on the bench right now. And it's okay,
but it still has way more driver distortion at 20 Hz than my midrange
system has at 1 KHz. And that's not linear enough for a lot of things
(although it's great for portable film systems which is what I am
probably using it for).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

Scott Dorsey wrote:

> Well, I've got one of the Auras on the bench right now. And it's
> okay, but it still has way more driver distortion at 20 Hz than my
> midrange system has at 1 KHz.

A good midrange system can have less that 0.1% THD at 1 KHz, which is a
tough number to match at 20 Hz and substantial levels.

> And that's not linear enough for a lot
> of things (although it's great for portable film systems which is
> what I am probably using it for).

@20Hz, not even the original sources are all that clean. Most of them have
more harmonics than fundamentals.

[Arny Krueger]

Scott Dorsey wrote:

> Well, I've got one of the Auras on the bench right now. And it's
> okay, but it still has way more driver distortion at 20 Hz than my
> midrange system has at 1 KHz.

A good midrange system can have less that 0.1% THD at 1 KHz, which is a
tough number to match at 20 Hz and substantial levels.

> And that's not linear enough for a lot
> of things (although it's great for portable film systems which is
> what I am probably using it for).

@20Hz, not even the original sources are all that clean. Most of them have
more harmonics than fundamentals.

[hank alrich]

Paul Stamler wrote:

> First question: What is the intended application, at what volume level, with
> what amplifier driving it?

I have a pair of boxes built as a curiousity in the mid-'70's. They're
sealed and we put 3 full-range JBL 8's in them, separate chambers for
each driver. Of course, they sound like **** because of the smearing
from the identical drivers. The plot from the White anachoic chamber was
an entertaining nightmare. It was an educational process and I learned
enough to avoid using them.

But the boxes are very well built from voidless marine plywood and I
have them sitting around doing nothing more than hold up a bench top.
I'd like to stuff them with little woofers. I'd like a useful range of
40 - 120 Hz, and reasonably clean. I have various amps here, and for
some situations I could point a pair of Crest PL400's at 'em. I know I
won't get to 4 ohms with three drivers, but these particular Crests
don't want to driver lower than 4 (nominal) ohms, into which they would
each deliver 900 watts RMS if run bridged.

I could use them in certain acoustic music situations where tremendous
volume isn't paramount, but obviously, with widdle woofers like that
they'd still have to be fairly stout to hang with the Bag End TA2000's
or sometimes the UPA1A's, thought those would be running far below their
full output.

I measured the faces of them today and might even be able to get 10"
speakers into them, depending on a given driver's mounting requirements.

This is a further exercise in curiousity, as I grub through stuff I have
here that isn't seeing service. I'm looking for a way to use these
boxes. If I succeed, I'll have to build something to hold up the bench.

--
ha

[hank alrich]

Paul Stamler wrote:

> First question: What is the intended application, at what volume level, with
> what amplifier driving it?

I have a pair of boxes built as a curiousity in the mid-'70's. They're
sealed and we put 3 full-range JBL 8's in them, separate chambers for
each driver. Of course, they sound like **** because of the smearing
from the identical drivers. The plot from the White anachoic chamber was
an entertaining nightmare. It was an educational process and I learned
enough to avoid using them.

But the boxes are very well built from voidless marine plywood and I
have them sitting around doing nothing more than hold up a bench top.
I'd like to stuff them with little woofers. I'd like a useful range of
40 - 120 Hz, and reasonably clean. I have various amps here, and for
some situations I could point a pair of Crest PL400's at 'em. I know I
won't get to 4 ohms with three drivers, but these particular Crests
don't want to driver lower than 4 (nominal) ohms, into which they would
each deliver 900 watts RMS if run bridged.

I could use them in certain acoustic music situations where tremendous
volume isn't paramount, but obviously, with widdle woofers like that
they'd still have to be fairly stout to hang with the Bag End TA2000's
or sometimes the UPA1A's, thought those would be running far below their
full output.

I measured the faces of them today and might even be able to get 10"
speakers into them, depending on a given driver's mounting requirements.

This is a further exercise in curiousity, as I grub through stuff I have
here that isn't seeing service. I'm looking for a way to use these
boxes. If I succeed, I'll have to build something to hold up the bench.

--
ha

[Scott Dorsey]

Arny Krueger > wrote:
>Scott Dorsey wrote:
>
>> Well, I've got one of the Auras on the bench right now. And it's
>> okay, but it still has way more driver distortion at 20 Hz than my
>> midrange system has at 1 KHz.
>
>A good midrange system can have less that 0.1% THD at 1 KHz, which is a
>tough number to match at 20 Hz and substantial levels.

Yes, this is sort of the point I was making. The current bass technology
is very far behind compared with what we can get at higher frequencies.

>> And that's not linear enough for a lot
>> of things (although it's great for portable film systems which is
>> what I am probably using it for).
>
>@20Hz, not even the original sources are all that clean. Most of them have
>more harmonics than fundamentals.

Sadly this is true, but it doesn't have to be. It's really sad to see what
typical optical soundtracks look like, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Arny Krueger > wrote:
>Scott Dorsey wrote:
>
>> Well, I've got one of the Auras on the bench right now. And it's
>> okay, but it still has way more driver distortion at 20 Hz than my
>> midrange system has at 1 KHz.
>
>A good midrange system can have less that 0.1% THD at 1 KHz, which is a
>tough number to match at 20 Hz and substantial levels.

Yes, this is sort of the point I was making. The current bass technology
is very far behind compared with what we can get at higher frequencies.

>> And that's not linear enough for a lot
>> of things (although it's great for portable film systems which is
>> what I am probably using it for).
>
>@20Hz, not even the original sources are all that clean. Most of them have
>more harmonics than fundamentals.

Sadly this is true, but it doesn't have to be. It's really sad to see what
typical optical soundtracks look like, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

hank alrich > wrote:
>
>But the boxes are very well built from voidless marine plywood and I
>have them sitting around doing nothing more than hold up a bench top.
>I'd like to stuff them with little woofers. I'd like a useful range of
>40 - 120 Hz, and reasonably clean. I have various amps here, and for
>some situations I could point a pair of Crest PL400's at 'em. I know I
>won't get to 4 ohms with three drivers, but these particular Crests
>don't want to driver lower than 4 (nominal) ohms, into which they would
>each deliver 900 watts RMS if run bridged.

Ahh! You got existing cabinets!

What volume, what venting, and how much money do you want to spend?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

hank alrich > wrote:
>
>But the boxes are very well built from voidless marine plywood and I
>have them sitting around doing nothing more than hold up a bench top.
>I'd like to stuff them with little woofers. I'd like a useful range of
>40 - 120 Hz, and reasonably clean. I have various amps here, and for
>some situations I could point a pair of Crest PL400's at 'em. I know I
>won't get to 4 ohms with three drivers, but these particular Crests
>don't want to driver lower than 4 (nominal) ohms, into which they would
>each deliver 900 watts RMS if run bridged.

Ahh! You got existing cabinets!

What volume, what venting, and how much money do you want to spend?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Scott Dorsey wrote:

> Ahh! You got existing cabinets!

Yes.

> What volume,

2 ft. cu., each cell, three cells per box. And as I said, if I recut the
faces I could get a 10" in there, too.

> what venting,

None. Cabs are sealed.

> and how much money do you want to spend?

Sssssshhh... I'm trying to find out what I might have to spend before I
talk about this out loud 'round here...

Haven't put a figure to it yet, as I've not had a clue yet what's
possible. But not the kind of money it took to buy the Meyers. <g>

--
ha

[hank alrich]

Scott Dorsey wrote:

> Ahh! You got existing cabinets!

Yes.

> What volume,

2 ft. cu., each cell, three cells per box. And as I said, if I recut the
faces I could get a 10" in there, too.

> what venting,

None. Cabs are sealed.

> and how much money do you want to spend?

Sssssshhh... I'm trying to find out what I might have to spend before I
talk about this out loud 'round here...

Haven't put a figure to it yet, as I've not had a clue yet what's
possible. But not the kind of money it took to buy the Meyers. <g>

--
ha

[Scott Dorsey]

hank alrich > wrote:
>Scott Dorsey wrote:
>
>> What volume,
>
>2 ft. cu., each cell, three cells per box. And as I said, if I recut the
>faces I could get a 10" in there, too.
>
>> what venting,
>
>None. Cabs are sealed.

You mean you have three spaces, each with two cubic feet per box?
That's 56 liters per cell, total of 168 liters. That's a good size for
an acoustic suspension box with a larger driver. I think the Vas for
most 8" woofers is going to be be too high, and so the cone will just
be flapping around without enough springiness to hold it in position.

Give Madisound a call. If anybody has anything intended for an acoustic
suspension box that size, it'll be them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

hank alrich > wrote:
>Scott Dorsey wrote:
>
>> What volume,
>
>2 ft. cu., each cell, three cells per box. And as I said, if I recut the
>faces I could get a 10" in there, too.
>
>> what venting,
>
>None. Cabs are sealed.

You mean you have three spaces, each with two cubic feet per box?
That's 56 liters per cell, total of 168 liters. That's a good size for
an acoustic suspension box with a larger driver. I think the Vas for
most 8" woofers is going to be be too high, and so the cone will just
be flapping around without enough springiness to hold it in position.

Give Madisound a call. If anybody has anything intended for an acoustic
suspension box that size, it'll be them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Scott Dorsey wrote:

> You mean you have three spaces, each with two cubic feet per box?

That is correct. Each box has three sealed 2 ft cu chambers.

> That's 56 liters per cell, total of 168 liters. That's a good size for
> an acoustic suspension box with a larger driver. I think the Vas for
> most 8" woofers is going to be be too high, and so the cone will just
> be flapping around without enough springiness to hold it in position.

So I should perhaps aim for 10" drivers, eh?

> Give Madisound a call. If anybody has anything intended for an acoustic
> suspension box that size, it'll be them.

Cool. I'll contact them, and as always, Scott, thanks.

--
ha

[hank alrich]

Scott Dorsey wrote:

> You mean you have three spaces, each with two cubic feet per box?

That is correct. Each box has three sealed 2 ft cu chambers.

> That's 56 liters per cell, total of 168 liters. That's a good size for
> an acoustic suspension box with a larger driver. I think the Vas for
> most 8" woofers is going to be be too high, and so the cone will just
> be flapping around without enough springiness to hold it in position.

So I should perhaps aim for 10" drivers, eh?

> Give Madisound a call. If anybody has anything intended for an acoustic
> suspension box that size, it'll be them.

Cool. I'll contact them, and as always, Scott, thanks.

--
ha

[Jay-AtlDigi]

In article >,
(Scott Dorsey) wrote:


> Give Madisound a call. If anybody has anything intended for an acoustic
> suspension box that size, it'll be them.
> --scott

Madisound is great. They'll also help you figure out which driver is
best for your box, and if they aren't busy, will even make you aware of
some of the other variables to think about. Most manufacturers have
several drivers in each size optimized for different criteria, so you'll
have to do some figuring no matter which brand you choose, or just beg
the Madisound folks to start you in the right direction. Another company
in Canada called Solen (http://www.solen.ca/) also sells drivers and has
those Volt woofers I mentioned. They're not quite as helpful as the
Madisound folks, but if you get the right person, they'll still give you
some guidance. Volt woofers are used in products like Quested and PMC
monitors and REL subwoofers among others. I have a Quested/REL setup at
my studio and when I found out that Volt made woofers for both, a little
light went on in my head...
--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com

[Jay-AtlDigi]

In article >,
(Scott Dorsey) wrote:


> Give Madisound a call. If anybody has anything intended for an acoustic
> suspension box that size, it'll be them.
> --scott

Madisound is great. They'll also help you figure out which driver is
best for your box, and if they aren't busy, will even make you aware of
some of the other variables to think about. Most manufacturers have
several drivers in each size optimized for different criteria, so you'll
have to do some figuring no matter which brand you choose, or just beg
the Madisound folks to start you in the right direction. Another company
in Canada called Solen (http://www.solen.ca/) also sells drivers and has
those Volt woofers I mentioned. They're not quite as helpful as the
Madisound folks, but if you get the right person, they'll still give you
some guidance. Volt woofers are used in products like Quested and PMC
monitors and REL subwoofers among others. I have a Quested/REL setup at
my studio and when I found out that Volt made woofers for both, a little
light went on in my head...
--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com

[Arny Krueger]

Scott Dorsey wrote:
> hank alrich > wrote:
>> Scott Dorsey wrote:
>>
>>> What volume,
>>
>> 2 ft. cu., each cell, three cells per box. And as I said, if I recut
>> the faces I could get a 10" in there, too.
>>
>>> what venting,
>>
>> None. Cabs are sealed.

> You mean you have three spaces, each with two cubic feet per box?
> That's 56 liters per cell, total of 168 liters. That's a good size
> for an acoustic suspension box with a larger driver. I think the Vas
> for most 8" woofers is going to be be too high, and so the cone will
> just be flapping around without enough springiness to hold it in
> position.

It may seem intuitively clear, but "flopping around" ain't what usually
happens. Not every speaker driver works only by means of acoustic
suspension, in fact very few do. Virtually all drivers have enough restoring
force in their suspensions so that the cones don't in fact "flap around". In
fact, a large percentage of all speaker drivers work without "flopping
around" even if placed in very large enclosures such as a room or the
basement of a house. If flopping around were a real problem, this real-world
result would not be observed.

If you put a driver in a "too large" enclosure, the undesirable outcome is
that the bass is kinda thin sounding. Looking at the system as
mass-spring-damper type system, it will turn out to be overdamped, not the
underdamped situation suggested by the phrase "flopping around". The
resonance of a smaller, more optimally-sized enclosure provides some needed
bass lift. If you add some equalization to get the desired bass response
with a driver in a too-large enclosure, things work out pretty well
sonically, but in some sense the system is not optimally designed.

The usual rule of thumb is that you want a driver with Vas about three times
the size of the box. IOW the volume of the box should be about 1/3 the Vas
of the driver. You're looking for a driver with a Vas of about 170 liters
to go with enclosures that are about 56 liters.

Here's a large online database of driver parameters:
http://www.thielesmall.com . If you search around with google, and read the
articles about box design, you can come up with a number of them.

Plugging in just a 10" nominal size, I find that the largest Vas 10" driver
in the database has a Vas of 229 liters. This is good news because it shows
that we aren't on mission impossible. There are even drivers with Vas that
is too high!

Vas versus box size is not a critical match. The box size = 1/3 Vas idea is
just a loose guideline. I suspect that a driver with a Vas of 120 liters or
more would perform fairly acceptably. You would have nearly total freedom in
matching drivers to this box if you would be willing to equalize the
resulting system. However, you would probably want to get a fairly efficient
system, so you want to avoid drivers with really low Vas. If you get a
driver with Vas that is too high, there is likely to be some natural lift in
the bass response at low frequencies. This is the usual result of a slightly
too-small enclosure for a given driver - somewhat undamped response.

By picking drivers with appropriate Vas, you can end up in the ballpark of
system with a good combination of efficiency and good bass response.

Once you have picked some candidate drivers, use any of the zillions of
online or downloadable Thiel-Small calculators to model the proposed system
and compare alternative drivers. Most of them will provide a chart of
expected frequency response quite quickly.

> Give Madisound a call. If anybody has anything intended for an
> acoustic suspension box that size, it'll be them.

The idea that every sealed box is "acoustic suspension" or should be
"acoustic suspension" is just plain false. IME limiting one's driver options
to just what Madisound stocks is a big mistake.

The other item in this design agenda is the fact that you seem to be
designing a speaker array. There is going to be some coupling that will
affect the final response of the system. Hopefully the drivers will be lined
up edge-to-edge. This will minimize lobing to some degree.

[Arny Krueger]

Scott Dorsey wrote:
> hank alrich > wrote:
>> Scott Dorsey wrote:
>>
>>> What volume,
>>
>> 2 ft. cu., each cell, three cells per box. And as I said, if I recut
>> the faces I could get a 10" in there, too.
>>
>>> what venting,
>>
>> None. Cabs are sealed.

> You mean you have three spaces, each with two cubic feet per box?
> That's 56 liters per cell, total of 168 liters. That's a good size
> for an acoustic suspension box with a larger driver. I think the Vas
> for most 8" woofers is going to be be too high, and so the cone will
> just be flapping around without enough springiness to hold it in
> position.

It may seem intuitively clear, but "flopping around" ain't what usually
happens. Not every speaker driver works only by means of acoustic
suspension, in fact very few do. Virtually all drivers have enough restoring
force in their suspensions so that the cones don't in fact "flap around". In
fact, a large percentage of all speaker drivers work without "flopping
around" even if placed in very large enclosures such as a room or the
basement of a house. If flopping around were a real problem, this real-world
result would not be observed.

If you put a driver in a "too large" enclosure, the undesirable outcome is
that the bass is kinda thin sounding. Looking at the system as
mass-spring-damper type system, it will turn out to be overdamped, not the
underdamped situation suggested by the phrase "flopping around". The
resonance of a smaller, more optimally-sized enclosure provides some needed
bass lift. If you add some equalization to get the desired bass response
with a driver in a too-large enclosure, things work out pretty well
sonically, but in some sense the system is not optimally designed.

The usual rule of thumb is that you want a driver with Vas about three times
the size of the box. IOW the volume of the box should be about 1/3 the Vas
of the driver. You're looking for a driver with a Vas of about 170 liters
to go with enclosures that are about 56 liters.

Here's a large online database of driver parameters:
http://www.thielesmall.com . If you search around with google, and read the
articles about box design, you can come up with a number of them.

Plugging in just a 10" nominal size, I find that the largest Vas 10" driver
in the database has a Vas of 229 liters. This is good news because it shows
that we aren't on mission impossible. There are even drivers with Vas that
is too high!

Vas versus box size is not a critical match. The box size = 1/3 Vas idea is
just a loose guideline. I suspect that a driver with a Vas of 120 liters or
more would perform fairly acceptably. You would have nearly total freedom in
matching drivers to this box if you would be willing to equalize the
resulting system. However, you would probably want to get a fairly efficient
system, so you want to avoid drivers with really low Vas. If you get a
driver with Vas that is too high, there is likely to be some natural lift in
the bass response at low frequencies. This is the usual result of a slightly
too-small enclosure for a given driver - somewhat undamped response.

By picking drivers with appropriate Vas, you can end up in the ballpark of
system with a good combination of efficiency and good bass response.

Once you have picked some candidate drivers, use any of the zillions of
online or downloadable Thiel-Small calculators to model the proposed system
and compare alternative drivers. Most of them will provide a chart of
expected frequency response quite quickly.

> Give Madisound a call. If anybody has anything intended for an
> acoustic suspension box that size, it'll be them.

The idea that every sealed box is "acoustic suspension" or should be
"acoustic suspension" is just plain false. IME limiting one's driver options
to just what Madisound stocks is a big mistake.

The other item in this design agenda is the fact that you seem to be
designing a speaker array. There is going to be some coupling that will
affect the final response of the system. Hopefully the drivers will be lined
up edge-to-edge. This will minimize lobing to some degree.

[Arny Krueger]

Richard Kuschel wrote:
>> What are the baddest ass mini wooferesque cone drivers of the 8"
>> persuasion?
>>
>> (Yes, I realize size matters. But this is about 8" speakers.)
>>
>> --
>> ha
>>
>>
>
> I don't know about the baddest, but I have a Velodyne 8" in my home
> theatre system.
>
> 600 Watts RMS amplifier and 28 Hz low frequency. Absolutely shakes
> the house.
>
> Coming from the bigger is better philosophy of the '60's, I couldn't
> believe it.

On the one hand, driver technology has come a long way since the 60s. In the
60s we did not yet had one of the most important discoveries related to
loudspeaker design particularly at low frequencies - Thiel-Small parameters.

OTOH, there is a problem with smaller drivers. Small drivers strongly tend
to have smaller Xmax, all other things being equal. Right now the largest
Xmax drivers around tend to be in the 12-15" range. If there were some
smaller drivers with larger Xmax, then the larger Xmax would offset the
smaller size of the driver. But, the geometry of conventional driver design
mitigates against this.

Nevertheless, we now have some speakers with smaller drivers that on balance
can be impressive performers.

[Arny Krueger]

Richard Kuschel wrote:
>> What are the baddest ass mini wooferesque cone drivers of the 8"
>> persuasion?
>>
>> (Yes, I realize size matters. But this is about 8" speakers.)
>>
>> --
>> ha
>>
>>
>
> I don't know about the baddest, but I have a Velodyne 8" in my home
> theatre system.
>
> 600 Watts RMS amplifier and 28 Hz low frequency. Absolutely shakes
> the house.
>
> Coming from the bigger is better philosophy of the '60's, I couldn't
> believe it.

On the one hand, driver technology has come a long way since the 60s. In the
60s we did not yet had one of the most important discoveries related to
loudspeaker design particularly at low frequencies - Thiel-Small parameters.

OTOH, there is a problem with smaller drivers. Small drivers strongly tend
to have smaller Xmax, all other things being equal. Right now the largest
Xmax drivers around tend to be in the 12-15" range. If there were some
smaller drivers with larger Xmax, then the larger Xmax would offset the
smaller size of the driver. But, the geometry of conventional driver design
mitigates against this.

Nevertheless, we now have some speakers with smaller drivers that on balance
can be impressive performers.

[hank alrich]

Arny Krueger wrote:

> The other item in this design agenda is the fact that you seem to be
> designing a speaker array. There is going to be some coupling that will
> affect the final response of the system. Hopefully the drivers will be lined
> up edge-to-edge. This will minimize lobing to some degree.

I predict this technical consideration will be a non-problem at the
frequencies involved with a subwoofer. Now, if the boxes were ten feet
tall...

--
ha

[hank alrich]

Arny Krueger wrote:

> The other item in this design agenda is the fact that you seem to be
> designing a speaker array. There is going to be some coupling that will
> affect the final response of the system. Hopefully the drivers will be lined
> up edge-to-edge. This will minimize lobing to some degree.

I predict this technical consideration will be a non-problem at the
frequencies involved with a subwoofer. Now, if the boxes were ten feet
tall...

--
ha

[Chris Hornbeck]

On Wed, 02 Jun 2004 13:54:27 GMT, (hank alrich)
wrote:

>I predict this technical consideration will be a non-problem at the
>frequencies involved with a subwoofer. Now, if the boxes were ten feet
>tall...

Sure. A half wavelength at 120 Hz is 4.7 feet, and within a half
wavelength things are still very omni.

Chris Hornbeck

[Chris Hornbeck]

On Wed, 02 Jun 2004 13:54:27 GMT, (hank alrich)
wrote:

>I predict this technical consideration will be a non-problem at the
>frequencies involved with a subwoofer. Now, if the boxes were ten feet
>tall...

Sure. A half wavelength at 120 Hz is 4.7 feet, and within a half
wavelength things are still very omni.

Chris Hornbeck