I'm looking for feedback on the best approach to take out of the
following options.
Option #1: Purchase one SVS 16-46 @ $479 or one SVS 2-39 @ $429
Option #2: Build homemade system consisting of (2) Dayton 15" Quatro
Series. This speaker shares similar characteristics of the Dayton
Titanic speakers. I plotted it response using WinISD and found its
response to be -5db @ 30hz and -10db @20 hz with a sealed enclosure of
3.3 cu ft.

Option #3: Same as Option #2 but using vented design which according
to WinISD would be flat down to about 24hz and -3db @ 20hz with a box
size of 7 cu ft. tuned to 20.65hz using a port with 14 cm in diameter
and 43.7cm long. How crucial is it to use a flared port and how
difficult is it to find flared ports for such projects.

The parameters of the Dayton 15" Quatro are as follows:
QTS: 0.41 Vas: 186.9 liters Fs: 21hz
Xmax: 10mm (not sure if one way or two way)
Qms: 14 QES: 0.42 SPL: 91.8db 300 watts rms 4ohms Cost: $75.00

Thanks to all,

bsguidry

"bsguidry" wrote in message
om...
I'm looking for feedback on the best approach to take out of the
following options.
Option #1: Purchase one SVS 16-46 @ $479 or one SVS 2-39 @ $429
Option #2: Build homemade system consisting of (2) Dayton 15" Quatro
Series. This speaker shares similar characteristics of the Dayton
Titanic speakers. I plotted it response using WinISD and found its
response to be -5db @ 30hz and -10db @20 hz with a sealed enclosure of
3.3 cu ft.

Option #3: Same as Option #2 but using vented design which according
to WinISD would be flat down to about 24hz and -3db @ 20hz with a box
size of 7 cu ft. tuned to 20.65hz using a port with 14 cm in diameter
and 43.7cm long. How crucial is it to use a flared port and how
difficult is it to find flared ports for such projects.

The parameters of the Dayton 15" Quatro are as follows:
QTS: 0.41 Vas: 186.9 liters Fs: 21hz
Xmax: 10mm (not sure if one way or two way)
Qms: 14 QES: 0.42 SPL: 91.8db 300 watts rms 4ohms Cost: $75.00

Thanks to all,

bsguidry

My suggestion would be to build your own sub. It's teh easiest of all DIY
projects and provides the most bang for the buck.

I would suggest that rather than the Dayton's you go to www.adireaudio.com
and look at their 12' and 15" woofers. I think they offer the cleanest,
deepest bass you can get for the money and the Shiva 12' is one of the best
bargains in subwoofers available.

Adire also provides finished units as well as DIY kits.

Good luck.

"bsguidry" wrote in message
om

I'm looking for feedback on the best approach to take out of the
following options.
Option #1: Purchase one SVS 16-46 @ $479 or one SVS 2-39 @ $429

Have you looked at Hsu's offerings?

Option #2: Build homemade system consisting of (2) Dayton 15" Quatro
Series. This speaker shares similar characteristics of the Dayton
Titanic speakers. I plotted it response using WinISD and found its
response to be -5db @ 30hz and -10db @20 hz with a sealed enclosure of
3.3 cu ft.

Option #3: Same as Option #2 but using vented design which according
to WinISD would be flat down to about 24hz and -3db @ 20hz with a box
size of 7 cu ft. tuned to 20.65hz using a port with 14 cm in diameter
and 43.7cm long.

Have you looked at Adire's woofer drivers?

You can judge subwoofer drivers on paper by looking at the product of cone
area and Xmax.

A big part of the economics of subwoofers relates to how you are going to
provide power and handle the crossover and equalization issues.

How crucial is it to use a flared port and how
difficult is it to find flared ports for such projects.

The purpose of flaring the port is to avoid "chuffing" noise due to
turbulence at the port caused by excessive air velocity. The alternative to
flaring is to use a larger port which means a larger enclosure.

Remember, the room is extremely important in bass response also.

If your going to go through that much trouble, make sure you aren't making a
subwoofer that goes too far down for the room response.

or, get an eq.

Regards,


Erik


"bsguidry" wrote in message
om...
I'm looking for feedback on the best approach to take out of the
following options.
Option #1: Purchase one SVS 16-46 @ $479 or one SVS 2-39 @ $429
Option #2: Build homemade system consisting of (2) Dayton 15" Quatro
Series. This speaker shares similar characteristics of the Dayton
Titanic speakers. I plotted it response using WinISD and found its
response to be -5db @ 30hz and -10db @20 hz with a sealed enclosure of
3.3 cu ft.

Option #3: Same as Option #2 but using vented design which according
to WinISD would be flat down to about 24hz and -3db @ 20hz with a box
size of 7 cu ft. tuned to 20.65hz using a port with 14 cm in diameter
and 43.7cm long. How crucial is it to use a flared port and how
difficult is it to find flared ports for such projects.

The parameters of the Dayton 15" Quatro are as follows:
QTS: 0.41 Vas: 186.9 liters Fs: 21hz
Xmax: 10mm (not sure if one way or two way)
Qms: 14 QES: 0.42 SPL: 91.8db 300 watts rms 4ohms Cost: $75.00

Thanks to all,

bsguidry

"Erik Squires" wrote in message
vers.com

Remember, the room is extremely important in bass response also.

Point well taken.

If your going to go through that much trouble, make sure you aren't
making a subwoofer that goes too far down for the room response.

Tain't no such thing! However, very small rooms can add bass boost at the
lowest frequencies, leading to a sort of woofy, thuddy sound. This means you
need less bass response at low frequencies, not no bass response.

or, get an eq.

Probably a good idea, regardless.

Since you brought up eq Erik, there is a trend in subwoofer design that I
don't see covered very often, but is quite valid and involves heavy use of
equalization. The basic idea is to put the subwoofer driver in a
minimally-sized cabinet which of course produces an elevated bass cutoff
frequency. Then you just add bass boost to restore the desired low frequency
response.

This approach usually requires far more amplifier power than the large box
approach. Therefore, it also requires subwoofer drivers with voice coils
that can take far more power. The best modern subwoofer drivers are up to
it. You might call this approach the "Sunfire" approach, although they
really don't really do it *right*.

You might think that this approach causes increased distortion at the lowest
frequencies, but as long as you don't have problems with amplifier
distortion, it doesn't have to be a problem. The distortion produced by most
subwoofers at low frequencies is primarily due to Xmax, and this approach
doesn't cause any more cone motion than occurs in larger boxes. Due to the
small box and small volume of trapped air, much more force is required to
obtain the cone motion, but that's generally not a problem as long as the
amp and the voice coil are up to handling the increased power levels.

Simply put, this approach trades clean amplifier power which now exists in
abundance for relatively low prices, for enclosure size. BTW, Sunfire is not
the only manufacturer capitalizing on this approach, and it has been long
described in the technical literature.

I did consider using Adire's Shiva and Tempest, however, WinICD
plotted out more impressive LFE and SPL graphs using any of the Dayton
drivers. How accurately does WinICD and similar programs predict real
world response?

Is it the concensus here that the Adire drivers would outperform the
Daytons?

Also, any thoughts about using any of these drivers in sealed vs.
ported enclosures. Would the LFE dropoff of the sealed be noticeable
in most cases? Would a -6db drop at 20hz be significant in the
majority of the audio visual media out there?

Thanks,

bsguidry

"bsguidry" wrote in message
m

I did consider using Adire's Shiva and Tempest, however, WinICD
plotted out more impressive LFE and SPL graphs using any of the Dayton
drivers. How accurately does WinICD and similar programs predict real
world response?

I tried to find something on the web about Winicd and goggle was very
uninformative. However, the basic means of calculation, if it's based on
driver Xmax, is pretty cut-and-dried at this point.

Is it the consensus here that the Adire drivers would outperform the
Daytons?

I can only speak for myself, and I have to admit that I have no personal
practical experience with any of the above. I think you're using a good
procedure here, plugging the available detailed specs into a model and
looking at projected results.

Also, any thoughts about using any of these drivers in sealed vs.
ported enclosures. Would the LFE dropoff of the sealed be noticeable
in most cases?

Well that's just it. The vented box gives you flatter response down to a
point, and response drops like a rock below that. You probably didn't need
me to say this, as it's well-known. My own subwoofer is vented, but F3 is
about 20 Hz so I'm not too worried about it. In its next incarnation it will
likely be sealed, far smaller and heavily equalized.

Would a -6db drop at 20hz be significant in the majority of the audio
visual media out there?

There's actually some data on the web that you can use to evaluate questions
like these, the chart at: http://www.pcavtech.com/techtalk/FR/index.htm .

If you rephrase this question to say: "Would a 6 dB half-octave wide
difference at 20 Hz be audible?", the chart says "marginally yes". IOW, it
would be somewhat audible with the occasional recording that has strong
sounds at 20 Hz, but it wouldn't be earth-shattering. It comes down to how
much of a perfectionist you are.

Wouldn't BagEnd (or something like that) be a better example of the EQ
boosted system you described?

How does Sunfire do it wrong, btw?

Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the permanent
magnet circuit of the motor under high current drive levels (as would
likely be encountered with a system that implements high EQ boosts in
the lowest frequency range). Naturally, this effect can be mostly
compensated with specific augmentations to the motor system, but your
garden variety subwoofer motor just won't keep a stable motor strength
when the current swings become substantial.

That's my 2 cts!

"dangling entity" wrote in message
om

Wouldn't BagEnd (or something like that) be a better example of the EQ
boosted system you described?

Why do you say that?

How does Sunfire do it wrong, btw?

Presumably driver parameters have a lot to do with it. In short, not enough
Xmax. The passive radiator needs to have *enough* Xmax, as well.

Once upon a time I saw Dumax test results for a larger Sunfire woofer
driver. I can't remember too many details except that at the time, they were
considered to be suboptimal for a product that would be loud and linear down
to 20 Hz.

Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the permanent
magnet circuit of the motor under high current drive levels (as would
likely be encountered with a system that implements high EQ boosts in
the lowest frequency range).

This doesn't seem to be a problem, at least with the Clark implementation.

Naturally, this effect can be mostly
compensated with specific augmentations to the motor system, but your
garden variety subwoofer motor just won't keep a stable motor strength
when the current swings become substantial.

I don't think that a high performance system would be based on drivers that
could reasonably be called "garden variety".

;-)

That's my 2 cts!

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

Wouldn't BagEnd (or something like that) be a better example of the EQ
boosted system you described?

Why do you say that?

Does this name not ring a bell, or are you saying it doesn't fit the
description at all? I was to understand that the product (if I got
the name right, that is) is basically a woofer put into a
smaller-than-usual sealed box, and a complementary bass boost is
applied in the built-in amplification to give the rated frequency
response.

The Sunfire drive is basically designed to "live" in a small box (in
conjunction with a similarly aspiring passive radiator), inherently.
Whether or not there is EQing involved, I'm not exactly sure. It's
really just an extreme take on a conventional vented design, AFAIK.


How does Sunfire do it wrong, btw?

Presumably driver parameters have a lot to do with it. In short, not enough
Xmax. The passive radiator needs to have *enough* Xmax, as well.

Once upon a time I saw Dumax test results for a larger Sunfire woofer
driver. I can't remember too many details except that at the time, they were
considered to be suboptimal for a product that would be loud and linear down
to 20 Hz.


Well, I wouldn't say Sunfire drivers are exactly lacking in the Xmax
category. When considering 20 Hz output however, just about anything
short of a large diameter driver is going to stress the Xmax
capability at even moderate SPL's. I think the Sunfire subwoofer
products present a sort of odd paradigm between compact form and low
frequency capability. The compact form naturally leads to smaller
driver sizes, but those drivers tend to do well in the low frequency
range where other drivers of similar size would not. The particular
driver parameters in combination with the extreme box loading in a
Sunfire enable a capability that not just any 10" driver (for
instance) could do if slapped into a box of that size. That's one
source of the "mystique", I imagine.

That said, a lot of people confuse that capability as a means for
"unlimited sub-bass output", regardless of room conditions. What the
Sunfire does, it does fairly well in a *smaller sized room* (which
would unsurprisingly benefit the most from a very compact subwoofer
design). Naturally, if you put it in a medium or larger sized room,
you will need more units to make that 20 Hz-ish range accessible.
That's just plain physics (not that I'm preaching to you), and there's
no way around that- not even for a Sunfire. I imagine a lot of people
had unreasonable expectations for the product when they put just one
in their medium sized room and expected to be palpitated with air
pressure waves. Naturally, just *one* Sunfire unit would find itself
overextended in such a situation, but people were evidently expecting
it to create miracles. That's my take on it, FWIW.


Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the permanent
magnet circuit of the motor under high current drive levels (as would
likely be encountered with a system that implements high EQ boosts in
the lowest frequency range).

This doesn't seem to be a problem, at least with the Clark implementation.


It's a phenomenon that effects virtually all VC style speakers. Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that care
to expose that sort of information about their product (if they have
even bothered to discern it). I don't believe Clark's Duomax
measurements would necessarily reveal its effects, either, unless
studies are expanded to study (very) large signal inputs, rather than
just standard small signal inputs to determine motor strength.

"dangling entity" wrote in message
om

"Arny Krueger" wrote in message
...

"dangling entity" wrote in message
om

Wouldn't BagEnd (or something like that) be a better example of the
EQ boosted system you described?

Why do you say that?

Does this name not ring a bell, or are you saying it doesn't fit the
description at all? I was to understand that the product (if I got
the name right, that is) is basically a woofer put into a
smaller-than-usual sealed box, and a complementary bass boost is
applied in the built-in amplification to give the rated frequency
response.

I guess my confusion relates to the fact that you mustn't have seen
Nousaine's post to this thread that discussed this specific product at
length. Further investigation shows that Nousaine's "bag end" post is only
posted in RAO, which means that you're posting from one of the other groups
that this thread is generally cross-posted to.

Here's a link to Nousaine's "bag end" post:

http://www.google.com/groups?selm=20...6%40mb-m23.aol
..com

I think you'll find it interesting.


The Sunfire drive is basically designed to "live" in a small box (in
conjunction with a similarly aspiring passive radiator), inherently.

I don't think so. The box is so small that the system resonance is closer to
50 Hz than 20.

Whether or not there is EQing involved, I'm not exactly sure. It's
really just an extreme take on a conventional vented design, AFAIK.

AFAIK it needs lots of eq.

How does Sunfire do it wrong, btw?

Presumably driver parameters have a lot to do with it. In short, not
enough Xmax. The passive radiator needs to have *enough* Xmax, as
well.

Once upon a time I saw Dumax test results for a larger Sunfire woofer
driver. I can't remember too many details except that at the time,
they were considered to be suboptimal for a product that would be
loud and linear down to 20 Hz.

Well, I wouldn't say Sunfire drivers are exactly lacking in the Xmax
category. When considering 20 Hz output however, just about anything
short of a large diameter driver is going to stress the Xmax
capability at even moderate SPL's.

Not quite. There are some drivers in the ca. 12" category that have soooooo
much Xmax that they can move more air than just about *any* 15 or 18 inch
driver. Here's an example:

http://www.jlaudio.com/subwoofers/pdfs/13W7_MAN.pdf

It's got 1.25 inches of linear Xmax in each direction. 2.5 inches or 64 mm
p-p two-way Xmax. Yup, the cone strokes 2.5 inches with low distortion!

I think the Sunfire subwoofer
products present a sort of odd paradigm between compact form and low
frequency capability. The compact form naturally leads to smaller
driver sizes, but those drivers tend to do well in the low frequency
range where other drivers of similar size would not. The particular
driver parameters in combination with the extreme box loading in a
Sunfire enable a capability that not just any 10" driver (for
instance) could do if slapped into a box of that size. That's one
source of the "mystique", I imagine.

The mystique comes from the advertising.

Here's a fairly detailed review of the sunfire. It says that the drivers are
9 inches in diameter and have 30 mm p-p two-way xmax.

http://www.hometheaterhifi.com/volume_4_1/sunsubre.html.

That said, a lot of people confuse that capability as a means for
"unlimited sub-bass output", regardless of room conditions. What the
Sunfire does, it does fairly well in a *smaller sized room* (which
would unsurprisingly benefit the most from a very compact subwoofer
design). Naturally, if you put it in a medium or larger sized room,
you will need more units to make that 20 Hz-ish range accessible.
That's just plain physics (not that I'm preaching to you), and there's
no way around that- not even for a Sunfire. I imagine a lot of people
had unreasonable expectations for the product when they put just one
in their medium sized room and expected to be palpitated with air
pressure waves. Naturally, just *one* Sunfire unit would find itself
overextended in such a situation, but people were evidently expecting
it to create miracles. That's my take on it, FWIW.

Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the
permanent magnet circuit of the motor under high current drive
levels (as would likely be encountered with a system that
implements high EQ boosts in the lowest frequency range).

This doesn't seem to be a problem, at least with the Clark
implementation.

It's a phenomenon that effects virtually all VC style speakers.

See item 7 on page 2 of the JL Audio PDF.

Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that care
to expose that sort of information about their product (if they have
even bothered to discern it). I don't believe Clark's Duomax
measurements would necessarily reveal its effects, either, unless
studies are expanded to study (very) large signal inputs, rather than
just standard small signal inputs to determine motor strength.

The Dumax can fully stroke large woofers such as the JL Audio unit above,
which means that it can and does apply relatively large currents to the
UUTs.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

"Arny Krueger" wrote in message
...


Here's a link to Nousaine's "bag end" post:

http://www.google.com/groups?selm=20...6%40mb-m23.aol
.com

I think you'll find it interesting.



OK, thanks. I'll check it out.

The Sunfire drive is basically designed to "live" in a small box (in
conjunction with a similarly aspiring passive radiator), inherently.

I don't think so. The box is so small that the system resonance is closer to
50 Hz than 20.


Everything is relative. True 50 Hz is not that low, but consider that
it is relatively low compared to where other typical 10" woofers would
end up if put in that same box. For all its worth, it does "live" in
an unusually small box for a 10" woofer.

Whether or not there is EQing involved, I'm not exactly sure. It's
really just an extreme take on a conventional vented design, AFAIK.

AFAIK it needs lots of eq.


OK, fair enough.



Well, I wouldn't say Sunfire drivers are exactly lacking in the Xmax
category. When considering 20 Hz output however, just about anything
short of a large diameter driver is going to stress the Xmax
capability at even moderate SPL's.

Not quite. There are some drivers in the ca. 12" category that have soooooo
much Xmax that they can move more air than just about *any* 15 or 18 inch
driver. Here's an example:

http://www.jlaudio.com/subwoofers/pdfs/13W7_MAN.pdf


Yes, you are correct. I did not mean to say that there were
absolutely no instances where the contrary exists. The W7 design
represents far beyond the regime of a typical woofer, you must agree.
It is more the exception than the norm, no? Of course, the 13W7 you
link to *is* essentially a 15" woofer as far as physical measurements
of the actual active regions of the driver. (The typical 15" woofer
often includes a good 2" total of space dedicated to gasket and
mounting region) That was a primary influence behind the nonstandard
size of the design.


It's got 1.25 inches of linear Xmax in each direction. 2.5 inches or 64 mm
p-p two-way Xmax. Yup, the cone strokes 2.5 inches with low distortion!


....low distortion not only from the generous motor and suspension
accomodations, but also from the FEA-based optimizations that address
aforementioned motor modulation issues under high current loads. Hey,
I wasn't intending to make a shameless JL Audio plug, but you did it
for me by bringing them up!

I think the Sunfire subwoofer
products present a sort of odd paradigm between compact form and low
frequency capability. The compact form naturally leads to smaller
driver sizes, but those drivers tend to do well in the low frequency
range where other drivers of similar size would not. The particular
driver parameters in combination with the extreme box loading in a
Sunfire enable a capability that not just any 10" driver (for
instance) could do if slapped into a box of that size. That's one
source of the "mystique", I imagine.

The mystique comes from the advertising.


....as it is for a great many products on the market. This is not to
confirm that there aren't also solid engineering features in the
product.

Here's a fairly detailed review of the sunfire. It says that the drivers are
9 inches in diameter and have 30 mm p-p two-way xmax.

http://www.hometheaterhifi.com/volume_4_1/sunsubre.html.


They are 10" drivers in every sense as far as what "industry
standards" considers a 10" driver. The 9" determination was simply to
describe the actual active region of the driver (as would be typical
of most other industry-standard 10" drivers). If that sounded
confusing, all I'm trying to say is that them saying it is 9" in
diameter does *not* mean it is 1" smaller (or .5" on one side) than
any other typical 10" driver. 30 mm p-p isn't too shabby, either.
Maybe not impressive any more now that we are in the "W7 age", but
still decent. I guess it would be comparable to a W6 design, and that
design (though quite old these days) ended up being quite venerable
amongst its competitors for a *long*, *long* time- arguably even to
this day.

That said, a lot of people confuse that capability as a means for
"unlimited sub-bass output", regardless of room conditions. What the
Sunfire does, it does fairly well in a *smaller sized room* (which
would unsurprisingly benefit the most from a very compact subwoofer
design). Naturally, if you put it in a medium or larger sized room,
you will need more units to make that 20 Hz-ish range accessible.
That's just plain physics (not that I'm preaching to you), and there's
no way around that- not even for a Sunfire. I imagine a lot of people
had unreasonable expectations for the product when they put just one
in their medium sized room and expected to be palpitated with air
pressure waves. Naturally, just *one* Sunfire unit would find itself
overextended in such a situation, but people were evidently expecting
it to create miracles. That's my take on it, FWIW.

Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the
permanent magnet circuit of the motor under high current drive
levels (as would likely be encountered with a system that
implements high EQ boosts in the lowest frequency range).

This doesn't seem to be a problem, at least with the Clark
implementation.

It's a phenomenon that effects virtually all VC style speakers.

See item 7 on page 2 of the JL Audio PDF.


From an insider's perspective, it has only been *minimized* to a
particular tolerance, not eliminated. I stand by my earlier
statement. VC's will have current flow, current flow will generate a
magnetic field, and that magnetic field will have an impact on the
static operation point of the motor circuit. You can do things in the
motor design to make it more or less sympathetic to the phenomenon
from there...

Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that care
to expose that sort of information about their product (if they have
even bothered to discern it). I don't believe Clark's Duomax
measurements would necessarily reveal its effects, either, unless
studies are expanded to study (very) large signal inputs, rather than
just standard small signal inputs to determine motor strength.

The Dumax can fully stroke large woofers such as the JL Audio unit above,
which means that it can and does apply relatively large currents to the
UUTs.

It does so [the cone displacement] by air pressure (applied by another
woofer), no? Hence, there is no requirement to use large input
currents to get a motor reading. More likely, a very small signal is
used to get motor readings at the various displacements so as to give
the most stable results, unperturbed from unnecessary ohmic heating of
the VC. They *could* do high signal tests (with additional
limitations), but this is not a requirement, nor a default step in the
standard test, AFAIK.

"Arny Krueger" wrote in message ...
"dangling entity" wrote in message
om

"Arny Krueger" wrote in message
...


Here's a link to Nousaine's "bag end" post:

http://www.google.com/groups?selm=20...6%40mb-m23.aol
.com

I think you'll find it interesting.



OK, thanks. I'll check it out.

The Sunfire drive is basically designed to "live" in a small box (in
conjunction with a similarly aspiring passive radiator), inherently.

I don't think so. The box is so small that the system resonance is closer to
50 Hz than 20.


Everything is relative. True 50 Hz is not that low, but consider that
it is relatively low compared to where other typical 10" woofers would
end up if put in that same box. For all its worth, it does "live" in
an unusually small box for a 10" woofer.

Whether or not there is EQing involved, I'm not exactly sure. It's
really just an extreme take on a conventional vented design, AFAIK.

AFAIK it needs lots of eq.


OK, fair enough.



Well, I wouldn't say Sunfire drivers are exactly lacking in the Xmax
category. When considering 20 Hz output however, just about anything
short of a large diameter driver is going to stress the Xmax
capability at even moderate SPL's.

Not quite. There are some drivers in the ca. 12" category that have soooooo
much Xmax that they can move more air than just about *any* 15 or 18 inch
driver. Here's an example:

http://www.jlaudio.com/subwoofers/pdfs/13W7_MAN.pdf


Yes, you are correct. I did not mean to say that there were
absolutely no instances where the contrary exists. The W7 design
represents far beyond the regime of a typical woofer, you must agree.
It is more the exception than the norm, no? Of course, the 13W7 you
link to *is* essentially a 15" woofer as far as physical measurements
of the actual active regions of the driver. (The typical 15" woofer
often includes a good 2" total of space dedicated to gasket and
mounting region) That was a primary influence behind the nonstandard
size of the design.


It's got 1.25 inches of linear Xmax in each direction. 2.5 inches or 64 mm
p-p two-way Xmax. Yup, the cone strokes 2.5 inches with low distortion!


....low distortion not only from the generous motor and suspension
accomodations, but also from the FEA-based optimizations that address
aforementioned motor modulation issues under high current loads. Hey,
I wasn't intending to make a shameless JL Audio plug, but you did it
for me by bringing them up!

I think the Sunfire subwoofer
products present a sort of odd paradigm between compact form and low
frequency capability. The compact form naturally leads to smaller
driver sizes, but those drivers tend to do well in the low frequency
range where other drivers of similar size would not. The particular
driver parameters in combination with the extreme box loading in a
Sunfire enable a capability that not just any 10" driver (for
instance) could do if slapped into a box of that size. That's one
source of the "mystique", I imagine.

The mystique comes from the advertising.


....as it is for a great many products on the market. This is not to
confirm that there aren't also solid engineering features in the
product.

Here's a fairly detailed review of the sunfire. It says that the drivers are
9 inches in diameter and have 30 mm p-p two-way xmax.

http://www.hometheaterhifi.com/volume_4_1/sunsubre.html.


They are 10" drivers in every sense as far as what "industry
standards" considers a 10" driver. The 9" determination was simply to
describe the actual active region of the driver (as would be typical
of most other industry-standard 10" drivers). If that sounded
confusing, all I'm trying to say is that them saying it is 9" in
diameter does *not* mean it is 1" smaller (or .5" on one side) than
any other typical 10" driver. 30 mm p-p isn't too shabby, either.
Maybe not impressive any more now that we are in the "W7 age", but
still decent. I guess it would be comparable to a W6 design, and that
design (though quite old these days) ended up being quite venerable
amongst its competitors for a *long*, *long* time- arguably even to
this day.

That said, a lot of people confuse that capability as a means for
"unlimited sub-bass output", regardless of room conditions. What the
Sunfire does, it does fairly well in a *smaller sized room* (which
would unsurprisingly benefit the most from a very compact subwoofer
design). Naturally, if you put it in a medium or larger sized room,
you will need more units to make that 20 Hz-ish range accessible.
That's just plain physics (not that I'm preaching to you), and there's
no way around that- not even for a Sunfire. I imagine a lot of people
had unreasonable expectations for the product when they put just one
in their medium sized room and expected to be palpitated with air
pressure waves. Naturally, just *one* Sunfire unit would find itself
overextended in such a situation, but people were evidently expecting
it to create miracles. That's my take on it, FWIW.

Finally, I think the one primary compromise to such systems is
increased modulation distortion due to the VC modulating the
permanent magnet circuit of the motor under high current drive
levels (as would likely be encountered with a system that
implements high EQ boosts in the lowest frequency range).

This doesn't seem to be a problem, at least with the Clark
implementation.

It's a phenomenon that effects virtually all VC style speakers.

See item 7 on page 2 of the JL Audio PDF.


From an insider's perspective, it has only been *minimized* to a
particular tolerance, not eliminated. I stand by my earlier
statement. VC's will have current flow, current flow will generate a
magnetic field, and that magnetic field will have an impact on the
static operation point of the motor circuit. You can do things in the
motor design to make it more or less sympathetic to the phenomenon
from there...

Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that care
to expose that sort of information about their product (if they have
even bothered to discern it). I don't believe Clark's Duomax
measurements would necessarily reveal its effects, either, unless
studies are expanded to study (very) large signal inputs, rather than
just standard small signal inputs to determine motor strength.

The Dumax can fully stroke large woofers such as the JL Audio unit above,
which means that it can and does apply relatively large currents to the
UUTs.

It does so [the cone displacement] by air pressure (applied by another
woofer), no? Hence, there is no requirement to use large input
currents to get a motor reading. More likely, a very small signal is
used to get motor readings at the various displacements so as to give
the most stable results, unperturbed from unnecessary ohmic heating of
the VC. They *could* do high signal tests (with additional
limitations), but this is not a requirement, nor a default step in the
standard test, AFAIK. Since this high input signal phenomenon is a
dynamic effect, not a static effect, additional demands on the
measuring technique would be called for to capture the effect.

"dangling entity" wrote in message
om
"Arny Krueger" wrote in message
...
"dangling entity" wrote in message
om

Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that
care to expose that sort of information about their product (if
they have even bothered to discern it). I don't believe Clark's
Duomax measurements would necessarily reveal its effects, either,
unless studies are expanded to study (very) large signal inputs,
rather than just standard small signal inputs to determine motor
strength.

The Dumax can fully stroke large woofers such as the JL Audio unit
above, which means that it can and does apply relatively large
currents to the UUTs.

It does so [the cone displacement] by air pressure (applied by another
woofer), no? Hence, there is no requirement to use large input
currents to get a motor reading. More likely, a very small signal is
used to get motor readings at the various displacements so as to give
the most stable results, unperturbed from unnecessary ohmic heating of
the VC. They *could* do high signal tests (with additional
limitations), but this is not a requirement, nor a default step in the
standard test, AFAIK.

Dumax uses two vastly different means, both air pressure and current through
the voice coil, to displace the cone. BTW, the air pressure does not come
from another woofer. It comes from an air pump.

http://www.dlcdesignaudio.com/dumax.htm shows the Dumax machine. The air
pressure source is connected to the test chamber via the black hose running
behind the left vertical test chamber support. The current source is inside
the interface unit which has two meters, and is sitting on the right half of
the table under the test chamber.

After many helpful comments here and with further reading on Adire vs.
Dayton subwoofers, I'm now tending towards the Adire Tempest in a
vented enclosure using Adire's plans for the Adire Alignment. This
enclosure offers a good compromise for HT and music listening.
Luckily the enclosure plans are highly detailed, therefore I should be
able to create an optimal enclosure.

I found a subwoofer comparison chart on Adire's website that compared
the Shiva's SPL at 20hz (I think it was at 20hz) to other quality subs
including the Dayton Titanic and the NHT 1259. The Shiva outperformed
all of the subs on the chart which contradicts the results I obtained
using WinISD, however, I'm willing to accept the real world results as
more realistic than those plotted in theory.

Now comes deciding on the amp. Unfortunately, the Tempest has two
8ohm voice coils. My Carver amp is not rated for 4 ohm bridged loads
and running it stereo into 8 ohms would reduce its overall power.
I'm looking into the Rythmic 350 which on paper delivers fairly clean
and well-damped power up to about 370 watts rms. It also has a rumble
filter, frequency crossover settings, and damping settings.

bsguidry

"bsguidry" wrote in message
om
After many helpful comments here and with further reading on Adire vs.
Dayton subwoofers, I'm now tending towards the Adire Tempest in a
vented enclosure using Adire's plans for the Adire Alignment. This
enclosure offers a good compromise for HT and music listening.
Luckily the enclosure plans are highly detailed, therefore I should be
able to create an optimal enclosure.

I found a subwoofer comparison chart on Adire's website that compared
the Shiva's SPL at 20hz (I think it was at 20hz) to other quality subs
including the Dayton Titanic and the NHT 1259. The Shiva outperformed
all of the subs on the chart which contradicts the results I obtained
using WinISD, however, I'm willing to accept the real world results as
more realistic than those plotted in theory.

I did the math and found that the difference you mention from
http://www.adireaudio.com/diy_audio/...dire/shiva.htm
is almost exactly projected by the difference in actual Xmax.

Now comes deciding on the amp. Unfortunately, the Tempest has two
8ohm voice coils. My Carver amp is not rated for 4 ohm bridged loads
and running it stereo into 8 ohms would reduce its overall power.

I was faced with a similar challenge when I was looking for power to drive
my ACI DV-12 with one of my modified Dyna ST-400s. I hooked one voice coil
to each side of the power amp and had plenty of bass.


I'm looking into the Rythmic 350 which on paper delivers fairly clean
and well-damped power up to about 370 watts rms. It also has a rumble
filter, frequency crossover settings, and damping settings.

I am unfamiliar with that amplifier and I can't find any online references
to is under the given name.

Were I buying a new subwoofer amp, I'd give serious consideration to the
Behringer EP2500 Power Amplifier

http://www.behringer.com/02_products...P2500&lang=eng