Tom,
I saw this line in your review of the Image Dynamics IDMAX 12
subwoofer:

"My modeling suggested that a 1.5-cubic-foot stuffed sealed box would
deliver optimal performance in my recently acquired 2001 Corvette
coupe."

Does your modeling software let you compensate for the
transfer function of various cars? Also, how did you incorporate the
effects of the stuffing in the box? Does the software do that as
well, or did you use a rule-of-thumb, like increasing the box volume
in your software by 10% to account for the stuffing?
I found your article very helpful. I'm only asking these
questions because not only did you use just about the largest sealed
box that Image Dynamics recommends, you stuffed it as well. What was
it that your software or other measurements taken from your Corvette
told you that led you to stuff the box?

Thanks,
Scott Gardner

(Scott Gardner) wrote:

Tom,
I saw this line in your review of the Image Dynamics IDMAX 12
subwoofer:

"My modeling suggested that a 1.5-cubic-foot stuffed sealed box would
deliver optimal performance in my recently acquired 2001 Corvette
coupe."

Does your modeling software let you compensate for the
transfer function of various cars?

I have several programs available but as a general rule I use Bassbox which has
a generic interior acoustics function that allow you to specify the frequency a
12-dB transfer function begins. While not the most sophisticated program
available it's relatively inexpensive and for lab and car interior/subwoofer
modeling it does a good job of describing what actually happens when a given
system is implemented and installed in the car.

Also, how did you incorporate the
effects of the stuffing in the box? Does the software do that as
well, or did you use a rule-of-thumb, like increasing the box volume
in your software by 10% to account for the stuffing?

BassBox has an internal function that predicts different stuffing densities
that also works reasonably well.

In other cases I find that with 0.5-2.0 ft3 boxes a stuffing density of 1 lb/
ft3 will yeild a roughly 25% increase in apparent internal box size. With many
modern woofers that work well with small sealed enclosures this is much less
important than it was 10 years ago.

All boxes I use are stuffed to at least 1/2 - lb/ft3 to help ensure that
higher frequency reflections off the rear wall of the woofer will be attenuated
before they are re-reflected back through the cone.

I found your article very helpful. I'm only asking these
questions because not only did you use just about the largest sealed
box that Image Dynamics recommends, you stuffed it as well. What was
it that your software or other measurements taken from your Corvette
told you that led you to stuff the box?

Thanks,
Scott Gardner

I always stuff my boxes. But nowadays it's more for the second reason than for
the apparent enclosure-size improvement.

By the way, as a general rule-of-thumb, all things equal, you can design for
higher SPL and low extension with a larger enclosure.

I have BassBox6 Pro and I agree with Tom it works great. I haven't gotten
aroung to mapping my transfer function but it's easy enough to do and BB6
will show you the predicted response. Very cool.



Paul Vina




"Nousaine" wrote in message
...
(Scott Gardner) wrote:

Tom,
I saw this line in your review of the Image Dynamics IDMAX 12
subwoofer:

"My modeling suggested that a 1.5-cubic-foot stuffed sealed box would
deliver optimal performance in my recently acquired 2001 Corvette
coupe."

Does your modeling software let you compensate for the
transfer function of various cars?

I have several programs available but as a general rule I use Bassbox
which has
a generic interior acoustics function that allow you to specify the
frequency a
12-dB transfer function begins. While not the most sophisticated program
available it's relatively inexpensive and for lab and car
interior/subwoofer
modeling it does a good job of describing what actually happens when a
given
system is implemented and installed in the car.

Also, how did you incorporate the
effects of the stuffing in the box? Does the software do that as
well, or did you use a rule-of-thumb, like increasing the box volume
in your software by 10% to account for the stuffing?

BassBox has an internal function that predicts different stuffing
densities
that also works reasonably well.

In other cases I find that with 0.5-2.0 ft3 boxes a stuffing density of 1
lb/
ft3 will yeild a roughly 25% increase in apparent internal box size. With
many
modern woofers that work well with small sealed enclosures this is much
less
important than it was 10 years ago.

All boxes I use are stuffed to at least 1/2 - lb/ft3 to help ensure that
higher frequency reflections off the rear wall of the woofer will be
attenuated
before they are re-reflected back through the cone.

I found your article very helpful. I'm only asking these
questions because not only did you use just about the largest sealed
box that Image Dynamics recommends, you stuffed it as well. What was
it that your software or other measurements taken from your Corvette
told you that led you to stuff the box?

Thanks,
Scott Gardner

I always stuff my boxes. But nowadays it's more for the second reason than
for
the apparent enclosure-size improvement.

By the way, as a general rule-of-thumb, all things equal, you can design
for
higher SPL and low extension with a larger enclosure.