I'm preparing to build an enclosure for the Adire Tempest driver using
Adire's plans called the "Adire Alignment". This will be a 7.56 cu
ft box with two 3" diameter ports. The sub is downfiring.

I have all the plans and needed wood measurements, however, I have
concern about how to stuff the recommended 4 lbs of polyfill. By
filling the entire encolsure evenly with 4 lbs of polyfill, I'm
concerned that there is some risk that the polyfill will settle around
the back of the driver or into the port tubes.

Any suggestions about how to prevent this? Could I use some type of
screen material or perhaps an additional brace (with numberous holes)
placed above the subwoofer?

Thanks,

bsguidry

On 19 Dec 2003 08:56:18 -0800, (bsguidry) wrote:

I'm preparing to build an enclosure for the Adire Tempest driver using
Adire's plans called the "Adire Alignment". This will be a 7.56 cu
ft box with two 3" diameter ports. The sub is downfiring.

I have all the plans and needed wood measurements, however, I have
concern about how to stuff the recommended 4 lbs of polyfill. By
filling the entire encolsure evenly with 4 lbs of polyfill, I'm
concerned that there is some risk that the polyfill will settle around
the back of the driver or into the port tubes.

Any suggestions about how to prevent this? Could I use some type of
screen material or perhaps an additional brace (with numberous holes)
placed above the subwoofer?

Thanks,

bsguidry

Stretch cords across the inside of the cabinet and weave the polyfill
through them.

d

_____________________________

http://www.pearce.uk.com

In article , (bsguidry) wrote:
I'm preparing to build an enclosure for the Adire Tempest driver using
Adire's plans called the "Adire Alignment". This will be a 7.56 cu
ft box with two 3" diameter ports. The sub is downfiring.

I have all the plans and needed wood measurements, however, I have
concern about how to stuff the recommended 4 lbs of polyfill. By
filling the entire encolsure evenly with 4 lbs of polyfill, I'm
concerned that there is some risk that the polyfill will settle around
the back of the driver or into the port tubes.

Any suggestions about how to prevent this? Could I use some type of
screen material or perhaps an additional brace (with numberous holes)
placed above the subwoofer?

Allthough it will settle some, the stuff holds itself somewhat. You can keep it back
by simple stapling some strands to the sides. I often use black polypropylene
gutter guard, which comes in rolls. Cut it and it can be stapled or tacked to the sides,
holding back the stuffing. Its possible to also glue or tie it around the driver basket.
There are many other things and methods to do the trick. I would not generally
recommend even stuffing a cabnet with ports. I usually just use 2-3 inches of
foam tacked to the sides of the box. By all means, keep the stuffing
away from the ports and drivers unless you want its effects.

greg

bsguidry wrote:

I'm preparing to build an enclosure for the Adire Tempest driver using
Adire's plans called the "Adire Alignment". This will be a 7.56 cu
ft box with two 3" diameter ports. The sub is downfiring.

Redesign the box for vertical placement of the loudspeaker. You will
like having done this in 10 years. Just my opinion, ymmv.

I have all the plans and needed wood measurements, however, I have
concern about how to stuff the recommended 4 lbs of polyfill. By
filling the entire encolsure evenly with 4 lbs of polyfill, I'm
concerned that there is some risk that the polyfill will settle around
the back of the driver or into the port tubes.

Any suggestions about how to prevent this? Could I use some type of
screen material or perhaps an additional brace (with numberous holes)
placed above the subwoofer?

Gregs suggestion on how to keep the polyfill in place will still apply.

bsguidry


Kind regards

Peter Larsen

--
************************************************** ***********
* My site is at: http://www.muyiovatki.dk *
************************************************** ***********

Peter Larsen wrote in message ...
bsguidry wrote:

I'm preparing to build an enclosure for the Adire Tempest driver using
Adire's plans called the "Adire Alignment". This will be a 7.56 cu
ft box with two 3" diameter ports. The sub is downfiring.

Redesign the box for vertical placement of the loudspeaker. You will
like having done this in 10 years. Just my opinion, ymmv.

I have all the plans and needed wood measurements, however, I have
concern about how to stuff the recommended 4 lbs of polyfill. By
filling the entire encolsure evenly with 4 lbs of polyfill, I'm
concerned that there is some risk that the polyfill will settle around
the back of the driver or into the port tubes.

Any suggestions about how to prevent this? Could I use some type of
screen material or perhaps an additional brace (with numberous holes)
placed above the subwoofer?

Gregs suggestion on how to keep the polyfill in place will still apply.

bsguidry


Kind regards

Peter Larsen

Thanks to all who have responded. I believe I will use a combination
of sticking the polyfill to the sides and perhaps using cords or twine
as a net above the driver and ports.

As far as mounting the driver for a vertical alignment, I'd like to
know more why I'd appreciate this design in 10 years. Unfortunately,
I have two toddlers who haven't learned to keep out of my
electronics. Having the sub mounted underneath would offer a bit more
protection than if it were side mounted.

bsguidry

bsguidry wrote:

As far as mounting the driver for a vertical alignment,
I'd like to know more why I'd appreciate this design in
10 years.

Gravity will eventually cause the loudspeaker unit to leave its correct
rest position. This is not something that happens fast, but eventually
it will happen.

Unfortunately, I have two toddlers who haven't learned
to keep out of my electronics.

Aha ...

Having the sub mounted underneath would offer a bit more
protection than if it were side mounted.

Indeed. Design sure never is simple .... and even if a metal screen is
used, then the spilled beverage and icecream risk remains. I would try
to find a solution with a hidden loudspeaker unit, but then it becomes a
total redesign. One way of getting the loudspeaker unit hidden is to go
for a bandpass reflex box with a front chamber instead. But you already
appear to have a lock on the target ... or do you?

http://www.tachyon.co.jp may be an interesting passtime if you want to
look for possible solutions that may be somewhat beyond your initial
aim. The also have a subsite for WE555 Replacement Diaphragm ... just as
an a pro pos to a thread in this forum some weeks ago.

bsguidry


Kind regards

Peter Larsen

--
************************************************** ***********
* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** ***********

On 22 Dec 2003 11:34:29 -0800, (bsguidry) wrote:

As far as mounting the driver for a vertical alignment, I'd like to
know more why I'd appreciate this design in 10 years. Unfortunately,
I have two toddlers who haven't learned to keep out of my
electronics. Having the sub mounted underneath would offer a bit more
protection than if it were side mounted.

The Tempest, as with most sub drivers, is designed to be used
vertically. If you mount it horizontally, it will over time sag on its
suspension, introducing non-linearity. Even with vertical mounting,
it's advisable to rotate the driver by 180 degrees every few years, to
avoid the cone eventually rubbing in the gap.

As it happens, I'm about to build a 'killer' sub using a pair of
Tempests and a 500 watt amp in a 200 litre sealed cabinet. The drivers
will be vertically mounted, for the reason given. It should be X-Max
limited to less than 20Hz, and provide in-room levels of 120dB from
20Hz up with corner mounting, with a low-Q alignment using Linkwitz
Transform equalisation.

Hopefully, this will be 'adequate', for somewhat less than the cost of
a REL Q201. :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

This is off topic but you might want to consider an infinite
baffle arrangement. It's inexpensive and easy to construct
arrangement that yields incredibly clean, low distortion, very
deep bass at unbelievable SPL. Certainly the cleanest and
loudest bass I've ever heard.

With multiple (hidden) drivers you can literally achieve house
damaging levels with a flat response from below 10Hz to well
above 100Hz...at a fraction of the cost of a comparable box sub.
All this without a monster amplifier and no big ugly box in the
corner (and no polyfill concerns). I usually recommend four high
excursion 15" drivers (Stryke AV15 is the current
performance/dollar leader but the older Adire Tempest and Dayton
15" drivers compete well). For $1k total (drivers, amp,
construction materials) you can blow windows out of their frames
without the drivers breaking a sweat (i.e. still within linear
Xmax).

IB maximizes Hoffman's Iron Law. Hoffman's Iron Law states that
the efficiency of a woofer system is directly proportional to its
cabinet volume and the cube of its cutoff frequency (the lowest
frequency it can usefully reproduce). With any box sub there is a
tradeoff between efficiency, volume, and low frequency response.
With IB the volume is 'infinite' which maximizes the efficiency
and cutoff to simply the properties of the bare driver. It
doesn't get any better. Power compression/distortion isn't an
issue like a box sub and you only need a relatively tiny amp.

FAQ:
https://home.comcast.net/~ttriff/

Gallery pictures pages 1 and 2 with construction links
https://home.comcast.net/~ttriff//page2IB-Gallery.html
https://home.comcast.net/~ttriff//page3IB-Gallery2.html

Forum
http://f20.parsimony.net/forum36475/

IB: no box, no box-like sound

"Rusty Boudreaux" wrote in message ...
This is off topic but you might want to consider an infinite
baffle arrangement. It's inexpensive and easy to construct
arrangement that yields incredibly clean, low distortion, very
deep bass at unbelievable SPL. Certainly the cleanest and
loudest bass I've ever heard.

With multiple (hidden) drivers you can literally achieve house
damaging levels with a flat response from below 10Hz to well
above 100Hz...at a fraction of the cost of a comparable box sub.
All this without a monster amplifier and no big ugly box in the
corner (and no polyfill concerns). I usually recommend four high
excursion 15" drivers (Stryke AV15 is the current
performance/dollar leader but the older Adire Tempest and Dayton
15" drivers compete well). For $1k total (drivers, amp,
construction materials) you can blow windows out of their frames
without the drivers breaking a sweat (i.e. still within linear
Xmax).

IB maximizes Hoffman's Iron Law. Hoffman's Iron Law states that
the efficiency of a woofer system is directly proportional to its
cabinet volume and the cube of its cutoff frequency (the lowest
frequency it can usefully reproduce). With any box sub there is a
tradeoff between efficiency, volume, and low frequency response.
With IB the volume is 'infinite' which maximizes the efficiency
and cutoff to simply the properties of the bare driver. It
doesn't get any better. Power compression/distortion isn't an
issue like a box sub and you only need a relatively tiny amp.

FAQ:
https://home.comcast.net/~ttriff/

Gallery pictures pages 1 and 2 with construction links
https://home.comcast.net/~ttriff//page2IB-Gallery.html
https://home.comcast.net/~ttriff//page3IB-Gallery2.html

Forum
http://f20.parsimony.net/forum36475/

IB: no box, no box-like sound

I wish I had investigated Infinite Baffles further prior to beginning.
I hadn't envisioned doing an infinite baffle in what appears to be
the standard approach on the websites above. It definitely would lead
to simpler carpentry and no huge boxes in the room. I may move to
this in the near future.

I've already begun work on the 214L box for the Tempest. The wood is
all cut and much of it assembled. I'll go from there.

One question about port tubes. When using flared port kits,
measurements are given for the center tube length. In the case of the
Tempest plans it indicates a center tube length of 11". I'm assuming
this is the actual length of the center tube piece before the flared
ends are attached. The flared ends slip over the center tube so
measuring it afterwards would be about 10.5".

bsguidry

On Tue, 23 Dec 2003 04:39:04 -0600, "Rusty Boudreaux"
wrote:

With any box sub there is a
tradeoff between efficiency, volume, and low frequency response.
With IB the volume is 'infinite' which maximizes the efficiency
and cutoff to simply the properties of the bare driver. It
doesn't get any better. Power compression/distortion isn't an
issue like a box sub and you only need a relatively tiny amp.

FAQ:
https://home.comcast.net/~ttriff/

Gallery pictures pages 1 and 2 with construction links
https://home.comcast.net/~ttriff//page2IB-Gallery.html
https://home.comcast.net/~ttriff//page3IB-Gallery2.html

Forum
http://f20.parsimony.net/forum36475/

IB: no box, no box-like sound

OTOH, your ceiling will rattle like crazy..........

BTW, if using an open baffle, watch out that you don't rip the
suspension loose at low frequencies, when you can easily drive *way*
beyond Xmax! Note that most of the ultra-long throw drivers are
intended for use in a relatively small sealed boxes, with heavy EQ and
big amps. Go to the Linkwitz Lab website, and run the numbers through
for large box volumes - you get Xmax limiting at low frequencies with
very low power.

BTW, I'm in a similar situation to you, I have a large loft space
above my listening room, but I'm going with a pair of Tempests in a
200 litre sealed box, driven by a 500 watt amp. This works pretty
well, Xmax limited from 30 Hz down so achieving maximum possible SPL,
but without much spare power to overload the driver. Should give a
clean 120 dB in-room from 20 Hz up.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Stewart Pinkerton" wrote in message
...
OTOH, your ceiling will rattle like crazy..........

If you use a manifold with opposing drivers it won't be any worse
than a box sub at the same SPL. Rattling, shaking, etc will be
solely from acoustic coupling.

BTW, if using an open baffle, watch out that you don't rip the
suspension loose at low frequencies, when you can easily drive
*way*
beyond Xmax! Note that most of the ultra-long throw drivers are

Sure but that's the beauty of an IB. Driving to Xmax yields the
maximum output regardless of alignment. For an IB you don't need
a monster amp to get to Xmax. Four AV15's will get you nearly
100dB at 5Hz within Xmax and around 120dB by 15Hz or so.

Ultra-long throw 15" drivers such as the Stryke AV15 handle
overdrive quite well. Xmax is 23mm but Xsus is over 30mm. The
suspension is designed to handle overdrive without damage up to
the power rating of the coil. That said, once you hit Xsus
you'll never want to do it again...the aluminum voice coil former
hitting the backplate sounds like a shotgun blast. With four
drivers we're talking over 20 liters of displacement at Xsus.
For another $700 you can make it 40 liters. An amp with an 8 Hz
double integrated 3rd-order Butterworth high-pass filter will
essentially eliminate hitting Xsus.

above my listening room, but I'm going with a pair of Tempests
in a
200 litre sealed box, driven by a 500 watt amp. This works
pretty

Four AV15's in an IB will give you 3x the output capability at
Xmax (15 liters vs 3 liters).

On Tue, 23 Dec 2003 22:21:52 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
OTOH, your ceiling will rattle like crazy..........

If you use a manifold with opposing drivers it won't be any worse
than a box sub at the same SPL. Rattling, shaking, etc will be
solely from acoustic coupling.

Well, unless you have the box on springs, it will also be due to
mechanical coupling. IME, ceilings are not so strongly built as
floors!

Ultra-long throw 15" drivers such as the Stryke AV15 handle
overdrive quite well. Xmax is 23mm but Xsus is over 30mm. The
suspension is designed to handle overdrive without damage up to
the power rating of the coil. That said, once you hit Xsus
you'll never want to do it again...the aluminum voice coil former
hitting the backplate sounds like a shotgun blast.

Yup - that was my point. You can certainly do this with an IB, and I
doubt that it does the components much good! :-)

With four
drivers we're talking over 20 liters of displacement at Xsus.
For another $700 you can make it 40 liters. An amp with an 8 Hz
double integrated 3rd-order Butterworth high-pass filter will
essentially eliminate hitting Xsus.

Or you can just use the correct size of sealed box and avoid the
problem altogether........

above my listening room, but I'm going with a pair of Tempests in a
200 litre sealed box, driven by a 500 watt amp. This works
pretty

Four AV15's in an IB will give you 3x the output capability at
Xmax (15 liters vs 3 liters).

Unfortunately, I have to use what's available in the UK, which doesn't
include the Stryke AV15 - and I can't afford a pair of Tumults!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Stewart Pinkerton" wrote in message
...
Well, unless you have the box on springs, it will also be due
to
mechanical coupling. IME, ceilings are not so strongly built as
floors!

Not so. With identical opposing drivers the mechanical forces
cancel. It's not like a box sub trying to walk it's way across
the floor.

Ultra-long throw 15" drivers such as the Stryke AV15 handle
overdrive quite well. Xmax is 23mm but Xsus is over 30mm.
The
suspension is designed to handle overdrive without damage up
to
the power rating of the coil. That said, once you hit Xsus
you'll never want to do it again...the aluminum voice coil
former
hitting the backplate sounds like a shotgun blast.

Yup - that was my point. You can certainly do this with an IB,
and I
doubt that it does the components much good! :-)

Stewart, I've always thought your comments were dead on but I
think you're blowing this way out of proportion. With a typical
IB setup you'll never hit Xsus. Even if you do it won't damage
the driver.

For example, I can play Telarc's DVD-A version of Tchaikovsky's
1812 Overture at such volume that I seriously worry my double
sash windows are going to come out the their frames. I'm talking
about pegging the radio shack SPL meter at 126dB before getting
scared and backing off the volume (even with earplugs). Not once
have those 7Hz digital cannons hit Xsus. Now I can hook up a
tone generator and hit Xsus with a 3Hz tone but how realistic is
that? The sub will play several times louder than my mains so
it's a moot point anyway. To get to the SPL numbers above I have
to turn off the main amplifers to keep from toasting the
speakers. Because of the IB's large headroom I can EQ the sub
for flat response from 10Hz up and hit reference levels without
running out of bass.

Tom Nousaine's IB has eight TC Sounds 15s (23.4mm Xmax) and he
has been unable to test maximum SPL at 10 Hz with a 5000 watt amp
due to his windows not being up to the task. To quote Tom,
"vinyl double windows twist in frame severely".

drivers we're talking over 20 liters of displacement at Xsus.
For another $700 you can make it 40 liters. An amp with an 8
Hz
double integrated 3rd-order Butterworth high-pass filter will
essentially eliminate hitting Xsus.

Or you can just use the correct size of sealed box and avoid
the
problem altogether........

Why? What problem? The poor sealed box has the problem due to
lack of displacement. If you're hitting Xsus with an IB then a
typical sealed box would have long since hit it's limit . A
sealed box of Tempests with equivalent displacement requires over
1000 liters for a Butterworth alignment. I'd rather have a small
discrete hole in my ceiling than a massive expensive box in the
room.

Four AV15's in an IB will give you 3x the output capability at
Xmax (15 liters vs 3 liters).

Unfortunately, I have to use what's available in the UK, which
doesn't
include the Stryke AV15 - and I can't afford a pair of Tumults!

Although the Tumult is the king of displacement I doubt anyone
would use on for IB due to cost. Since an IB lends itself to
multiple drivers it's more economical to use 'lesser' drivers.
Four Tempests will get you the same displacement as two Tumults.

Seriously, the Tempest is an excellent driver for an IB. Along
with the Dayton 15" drivers (available internationally through
partsexpress) the Tempest was the most popular IB driver until
the AV15 came along. The AV15 has about 50% more displacement
per driver than a Tempest or Dayton and costs slightly less per
liter. For the same output you just need a few more
Tempests...or fewer AV15s.

If you want an AV15 (or multiple ones) I'll order them from
acoustic-visions and ship them to you at my cost (no added fee).
You've been posting here long enough...I trust you

On Wed, 24 Dec 2003 17:28:39 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Well, unless you have the box on springs, it will also be due
to
mechanical coupling. IME, ceilings are not so strongly built as
floors!

Not so. With identical opposing drivers the mechanical forces
cancel. It's not like a box sub trying to walk it's way across
the floor.

That's certainly the logical way to minimise box rattle.

Ultra-long throw 15" drivers such as the Stryke AV15 handle
overdrive quite well. Xmax is 23mm but Xsus is over 30mm. The
suspension is designed to handle overdrive without damage up to
the power rating of the coil. That said, once you hit Xsus
you'll never want to do it again...the aluminum voice coil former
hitting the backplate sounds like a shotgun blast.

Yup - that was my point. You can certainly do this with an IB, and I
doubt that it does the components much good! :-)

Stewart, I've always thought your comments were dead on but I
think you're blowing this way out of proportion. With a typical
IB setup you'll never hit Xsus. Even if you do it won't damage
the driver.

OK, I'll take your word on that, but voice coils slamming into
backplates (as you yourself describe) doesn't sound like a recipe for
longevity!

For example, I can play Telarc's DVD-A version of Tchaikovsky's
1812 Overture at such volume that I seriously worry my double
sash windows are going to come out the their frames. I'm talking
about pegging the radio shack SPL meter at 126dB before getting
scared and backing off the volume (even with earplugs). Not once
have those 7Hz digital cannons hit Xsus. Now I can hook up a
tone generator and hit Xsus with a 3Hz tone but how realistic is
that? The sub will play several times louder than my mains so
it's a moot point anyway. To get to the SPL numbers above I have
to turn off the main amplifers to keep from toasting the
speakers. Because of the IB's large headroom I can EQ the sub
for flat response from 10Hz up and hit reference levels without
running out of bass.

OK, so long as you're happy with it. Since I need 500 watts into 4
ohms to drive a Tempest fully for my target 115dB at 30-100Hz, I see
no harm in cushioning the driver by using a box sized so that max
power just drops below Xmax from 20Hz down. I'm not wasting any power
'cos it's there anyway, and I protect the drivers from any wayward
infrabass accidents.

Tom Nousaine's IB has eight TC Sounds 15s (23.4mm Xmax) and he
has been unable to test maximum SPL at 10 Hz with a 5000 watt amp
due to his windows not being up to the task. To quote Tom,
"vinyl double windows twist in frame severely".

Yup, I'm familiar with his weapon of house destruction!

drivers we're talking over 20 liters of displacement at Xsus.
For another $700 you can make it 40 liters. An amp with an 8 Hz
double integrated 3rd-order Butterworth high-pass filter will
essentially eliminate hitting Xsus.

Or you can just use the correct size of sealed box and avoid the
problem altogether........

Why? What problem? The poor sealed box has the problem due to
lack of displacement. If you're hitting Xsus with an IB then a
typical sealed box would have long since hit it's limit . A
sealed box of Tempests with equivalent displacement requires over
1000 liters for a Butterworth alignment. I'd rather have a small
discrete hole in my ceiling than a massive expensive box in the
room.

You can still have the box in the loft space, and a Linkwitz transform
equaliser will give you any alignment you want. A small box doesn't
have to mean a high Qts in 2003/4. I guess I'm just hedging my bets.
Besides, SWMBO doesn't want a hole in the ceiling!

You do raise an interesting point, however, as I'm having trouble
running the numbers as tpo how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

Four AV15's in an IB will give you 3x the output capability at
Xmax (15 liters vs 3 liters).

Unfortunately, I have to use what's available in the UK, which doesn't
include the Stryke AV15 - and I can't afford a pair of Tumults!

Although the Tumult is the king of displacement I doubt anyone
would use on for IB due to cost. Since an IB lends itself to
multiple drivers it's more economical to use 'lesser' drivers.
Four Tempests will get you the same displacement as two Tumults.

In your particular type of IB, this is true, although for 'in-room'
IBs the Tumult and DPL12 are sonically superior due to their rear
basket aerodynamics.

Seriously, the Tempest is an excellent driver for an IB. Along
with the Dayton 15" drivers (available internationally through
partsexpress) the Tempest was the most popular IB driver until
the AV15 came along. The AV15 has about 50% more displacement
per driver than a Tempest or Dayton and costs slightly less per
liter. For the same output you just need a few more
Tempests...or fewer AV15s.

If you want an AV15 (or multiple ones) I'll order them from
acoustic-visions and ship them to you at my cost (no added fee).
You've been posting here long enough...I trust you

Do you have Thiele Small numbers for the AV15? I might take you up on
that if I can't source them any other way. As you say, displacement is
everything at LF.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:

You do raise an interesting point, however, as I'm having trouble
running the numbers as tpo how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

Nobody seem to worry about air distortion in spite of using 4:1 or
higher (guesstimated) compression in loading the room, including
distortion due to the asymmetric airload experienced by the drivers (box
with 5 (?) ceiling mounted drivers and small room entry seen on some
site linked to).

Stewart Pinkerton | Music is Art - Audio is Engineering

Seasons greetings, but not to the spammers celebrating with 50% extra
spam to my mailbox :-(


Kind regards, spammers excluded

Peter Larsen

--
************************************************** *************
* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** *******

"Stewart Pinkerton" wrote in message


On Wed, 24 Dec 2003 17:28:39 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Well, unless you have the box on springs, it will also be due to
mechanical coupling. IME, ceilings are not so strongly built as
floors!

Not so. With identical opposing drivers the mechanical forces
cancel. It's not like a box sub trying to walk it's way across
the floor.

That's certainly the logical way to minimise box rattle.

IME it's a working plan. You may see both Nousaine and I referring to a
pair of subwoofers engineered and built by our friend Dave Clark. He went
this route and it just works.

Ultra-long throw 15" drivers such as the Stryke AV15 handle
overdrive quite well. Xmax is 23mm but Xsus is over 30mm. The
suspension is designed to handle overdrive without damage up to
the power rating of the coil. That said, once you hit Xsus
you'll never want to do it again...the aluminum voice coil former
hitting the backplate sounds like a shotgun blast.

Yup - that was my point. You can certainly do this with an IB, and I
doubt that it does the components much good! :-)

Stewart, I've always thought your comments were dead on but I
think you're blowing this way out of proportion. With a typical
IB setup you'll never hit Xsus. Even if you do it won't damage
the driver.

OK, I'll take your word on that, but voice coils slamming into
backplates (as you yourself describe) doesn't sound like a recipe for
longevity!

Agreed.

For example, I can play Telarc's DVD-A version of Tchaikovsky's
1812 Overture at such volume that I seriously worry my double
sash windows are going to come out the their frames. I'm talking
about pegging the radio shack SPL meter at 126dB before getting
scared and backing off the volume (even with earplugs). Not once
have those 7Hz digital cannons hit Xsus. Now I can hook up a
tone generator and hit Xsus with a 3Hz tone but how realistic is
that? The sub will play several times louder than my mains so
it's a moot point anyway. To get to the SPL numbers above I have
to turn off the main amplifers to keep from toasting the
speakers. Because of the IB's large headroom I can EQ the sub
for flat response from 10Hz up and hit reference levels without
running out of bass.

OK, so long as you're happy with it. Since I need 500 watts into 4
ohms to drive a Tempest fully for my target 115dB at 30-100Hz, I see
no harm in cushioning the driver by using a box sized so that max
power just drops below Xmax from 20Hz down. I'm not wasting any power
'cos it's there anyway, and I protect the drivers from any wayward
infrabass accidents.

The approach that Clark used was along similar lines. The boxes are minimal,
but large enough for the maximum rated driver motor force to stimulate
enough cone motion to meet design goals for low bass.

Tom Nousaine's IB has eight TC Sounds 15s (23.4mm Xmax) and he
has been unable to test maximum SPL at 10 Hz with a 5000 watt amp
due to his windows not being up to the task. To quote Tom,
"vinyl double windows twist in frame severely".

Yup, I'm familiar with his weapon of house destruction!

Last time I was there the house was still standing and seemed to be
suffering minimal damage. It seems to be a fairly ordinary modern box with
normal to-code wood frame structure and drywall. A tad flimsy compared to
mine, but if I had my druthers...

drivers we're talking over 20 liters of displacement at Xsus.
For another $700 you can make it 40 liters. An amp with an 8 Hz
double integrated 3rd-order Butterworth high-pass filter will
essentially eliminate hitting Xsus.

Agreed.

Or you can just use the correct size of sealed box and avoid the
problem altogether........

Why? What problem?

Agreed. I've suffered with a subwoofer box the size of a nice freezer chest
in my living room for something like 25 years. In the days when it was
built, 400 wpc was a BIIIIIG amp. Good equalizers were not the everyday
items they are today. Thiel-Small was still fairly new. When I do it all
over again it's gonna be a minimal-sized box. The basement solution is a
non-starter the reinforced-concrete and steel box I live in.

The poor sealed box has the problem due to
lack of displacement. If you're hitting Xsus with an IB then a
typical sealed box would have long since hit it's limit . A
sealed box of Tempests with equivalent displacement requires over
1000 liters for a Butterworth alignment. I'd rather have a small
discrete hole in my ceiling than a massive expensive box in the
room.

You can still have the box in the loft space, and a Linkwitz transform
equaliser will give you any alignment you want. A small box doesn't
have to mean a high Qts in 2003/4. I guess I'm just hedging my bets.
Besides, SWMBO doesn't want a hole in the ceiling!

Slits work and are pretty inconspicious. It's all a matter of hydraulics.

You do raise an interesting point, however, as I'm having trouble
running the numbers as to how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

I see several approaches:

Crib details from a working design.

Forget the port and equalize

Build a scale model and then multiply by a suitable integer

Arny Krueger wrote:

You do raise an interesting point, however, as I'm having trouble
running the numbers as to how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

I see several approaches:

Crib details from a working design.

Forget the port and equalize

Build a scale model and then multiply by a suitable integer

Horn it.

--
************************************************** *************
* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** *******

"Stewart Pinkerton" wrote in message
...
Besides, SWMBO doesn't want a hole in the ceiling!

You do raise an interesting point, however, as I'm having
trouble
running the numbers as tpo how small the hole in the ceiling
can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from
your
own experience?

There are two things to consider. Manifold cross sectional area
and opening size.

In a nutshell, if the manifold's cross sectional area and opening
is less than the driver's summed Sd, then it becomes a bandpass
design with a fairly low tuned low pass filter. Once the Sd/area
rises above about 3:1 you can start getting harmonic distortion.
The opening L:W ratio should be less than about 1.3:1 to keep
slit diffraction from nonlinear loading of the drivers and to
average out internal standing waves.

However, my opening is 16"x16" or only 1/2 the total Sd. It's a
huge hole but my ceiling is 12 feet up and painted black (front
projection theater) so the hole is essentially invisible even
with the lights on. Even at obscene levels I hear no port noise
and it doesn't seem to affect the frequency response or add
harmonics (ECM8000 measurement mic).

One IB forum member is using two 4"x10" HVAC floor vents with two
Dayton 15" drivers due to wife factors. Even without considering
the grill obstruction this is less than 1/3 Sd so would seem bad.
However, he won't stop gushing about how great it is. He has
some pictures of his manifold/vents he
http://users.rcn.com/mjrjunk/

Do you have Thiele Small numbers for the AV15? I might take you
up on
that if I can't source them any other way. As you say,
displacement is
everything at LF.

The AV15s were going for $165 USD during preorder but that's over
and they're now $205. Still a great bargain for IB but a little
more pricey.

http://www.stryke.com/AVseries.html
Fs: 22.39 Hz
Qms: 5.293
Qes: .517
Qts: .471
Vas: 140.1L
2.95 ohm
Z: 4 ohm
(dual 2ohm)
BL: 16.84 Tm
Cms: .143 mm/N
Mms: 353g
Rms: 9.391kg/s
Le: 3.5mH
Pe: 500W cont.
2.83V: 91.15dB
Xmax: 23 mm
Xsus: 30 mm
Sd: 830 sq cm
Vd: 3.8 L

Arny Krueger wrote:

You do raise an interesting point, however, as I'm having trouble
running the numbers as to how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

I see several approaches:

Crib details from a working design.

I'd like to, but I don't know where to look!

Forget the port and equalize

That's the most likely scenario - sealed box built into a room corner
and disguised. Mind you, if I can source Stryke AV15s in the UK, I'm
tempted to leave the alloy cones on show!

Build a scale model and then multiply by a suitable integer

Doesn't work - different Reynold's number.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Thu, 25 Dec 2003 13:32:47 +0100, Peter Larsen
wrote:

Stewart Pinkerton wrote:

You do raise an interesting point, however, as I'm having trouble
running the numbers as tpo how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

Nobody seem to worry about air distortion in spite of using 4:1 or
higher (guesstimated) compression in loading the room, including
distortion due to the asymmetric airload experienced by the drivers (box
with 5 (?) ceiling mounted drivers and small room entry seen on some
site linked to).

Could you give me a pointer to such a site? It's the idea of a *big*
hole in the ceiling that is caused WAF problems.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Thu, 25 Dec 2003 09:31:58 -0500, "Arny Krueger"
wrote:

"Stewart Pinkerton" wrote in message


On Wed, 24 Dec 2003 17:28:39 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Well, unless you have the box on springs, it will also be due to
mechanical coupling. IME, ceilings are not so strongly built as
floors!

Not so. With identical opposing drivers the mechanical forces
cancel. It's not like a box sub trying to walk it's way across
the floor.

That's certainly the logical way to minimise box rattle.

IME it's a working plan. You may see both Nousaine and I referring to a
pair of subwoofers engineered and built by our friend Dave Clark. He went
this route and it just works.

It certainly should work, if you carefully align the driver
centrelines and have the drivers perfectly parallel. I canna' change
the laws o' physics (Newton's 2nd in this case), cap'n! :-)

Tom Nousaine's IB has eight TC Sounds 15s (23.4mm Xmax) and he
has been unable to test maximum SPL at 10 Hz with a 5000 watt amp
due to his windows not being up to the task. To quote Tom,
"vinyl double windows twist in frame severely".

Yup, I'm familiar with his weapon of house destruction!

Last time I was there the house was still standing and seemed to be
suffering minimal damage. It seems to be a fairly ordinary modern box with
normal to-code wood frame structure and drywall. A tad flimsy compared to
mine, but if I had my druthers...

Yes, I'm expecting very good bass drive, as my room has a concrete
slab floor and 13" brick and block walls. Even the ceiling is heavily
joisted, so it shouldn't absorb *too* much bass, according to LspCAD.

The poor sealed box has the problem due to
lack of displacement. If you're hitting Xsus with an IB then a
typical sealed box would have long since hit it's limit . A
sealed box of Tempests with equivalent displacement requires over
1000 liters for a Butterworth alignment. I'd rather have a small
discrete hole in my ceiling than a massive expensive box in the
room.

You can still have the box in the loft space, and a Linkwitz transform
equaliser will give you any alignment you want. A small box doesn't
have to mean a high Qts in 2003/4. I guess I'm just hedging my bets.
Besides, SWMBO doesn't want a hole in the ceiling!

Slits work and are pretty inconspicious. It's all a matter of hydraulics.

Well, pneumatics and aerodynamics, but I know what you mean! :-)

My main concern is to keep the hole close to the room corner, to
maximise 1/8 space gain. OTOH, I can see how a long slit might be
useful in smoothing the response across the room. Decisions,
decisions........................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 26 Dec 2003 02:47:23 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Besides, SWMBO doesn't want a hole in the ceiling!

You do raise an interesting point, however, as I'm having trouble
running the numbers as tpo how small the hole in the ceiling can be
before it causes problems with either port noise or turning the
manifold into a reflex cabinet. Any advice on that mattter from your
own experience?

There are two things to consider. Manifold cross sectional area
and opening size.

In a nutshell, if the manifold's cross sectional area and opening
is less than the driver's summed Sd, then it becomes a bandpass
design with a fairly low tuned low pass filter.

Aah! Of course. I'd completely forgotten bandpass principles! Doh!

Once the Sd/area
rises above about 3:1 you can start getting harmonic distortion.
The opening L:W ratio should be less than about 1.3:1 to keep
slit diffraction from nonlinear loading of the drivers and to
average out internal standing waves.

Hmmmm. Not so sure about this one, as there won't be any standing
waves in the 150Hz passband, but I take your point about possible
distortion from pressure loading - that was my main concern.

However, my opening is 16"x16" or only 1/2 the total Sd. It's a
huge hole but my ceiling is 12 feet up and painted black (front
projection theater) so the hole is essentially invisible even
with the lights on. Even at obscene levels I hear no port noise
and it doesn't seem to affect the frequency response or add
harmonics (ECM8000 measurement mic).

Ah, OK. I'd be using a an 11" x 11" hole for that ratio, but it's a
white ceiling 9 feet up, so rather more visible!

One IB forum member is using two 4"x10" HVAC floor vents with two
Dayton 15" drivers due to wife factors. Even without considering
the grill obstruction this is less than 1/3 Sd so would seem bad.
However, he won't stop gushing about how great it is. He has
some pictures of his manifold/vents he
http://users.rcn.com/mjrjunk/

Thanks, that's exactly the kind of thing I was looking for. I'll start
running the numbers again for a 'semi-bandpass' design, but like you
say, that looks like an effective ratio of around 4:1 with the grilles
on. I probably could get away with a couple of large ventilation
grilles, Anne could claim that we've installed air-con! :-)

It does strike me that I'd need to be careful about turbulence noise,
but that's a problem for another day......

Do you have Thiele Small numbers for the AV15? I might take you up on
that if I can't source them any other way. As you say, displacement is
everything at LF.

The AV15s were going for $165 USD during preorder but that's over
and they're now $205. Still a great bargain for IB but a little
more pricey.

http://www.stryke.com/AVseries.html
Fs: 22.39 Hz
Qms: 5.293
Qes: .517
Qts: .471
Vas: 140.1L
2.95 ohm
Z: 4 ohm
(dual 2ohm)
BL: 16.84 Tm
Cms: .143 mm/N
Mms: 353g
Rms: 9.391kg/s
Le: 3.5mH
Pe: 500W cont.
2.83V: 91.15dB
Xmax: 23 mm
Xsus: 30 mm
Sd: 830 sq cm
Vd: 3.8 L

Thanks Rusty, I did find them after trawling the Stryke site. I've
e-mailed them for a quote, as their on-line store implies world-wide
shipping, so we'll see what transpires. I must say that they are the
coolest *looking* drivers around, with those big alloy cones!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:

Nobody seem to worry about air distortion ...

Could you give me a pointer to such a site? It's the idea of a *big*
hole in the ceiling that is caused WAF problems.

http://t-3.cc/users/audioworx/page13-12Shiva1.html

- a subpage of http://www.klone-audio.com/ - 12 large bass units firing
into a box with an estimated 12 by 12 inch opening into the listening
room.

For a more practical implementation of using multiple loudspeakers one
should in my opinion think differently. I would arrange a row of
loudspeakers on the loft in each side of the room and let the sound
enter the room via a long slit near the ceiling/wall junction. It would
still be possible to mount the loudspeakers vertically for longevity
(playing "downwards-sideways" into the slit) and it could be implemented
very discreetly. It will also provide a superiour coupling to the room.

|\
\
speaker(s) here \
playing - \
\
______________| \
- notice the consequence
ceiling ^ w | of too loud music ...
a | the roof must be securely
l | fastened to the building
l | to prevent this .... O;-)


Stewart Pinkerton | Music is Art - Audio is Engineering

Peerless has a 10" sub-bass that looks about right if used in multiples.


Kind regards

Peter Larsen

--
************************************************** *************
* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** *******

"Stewart Pinkerton" wrote in message
...
Thanks Rusty, I did find them after trawling the Stryke site.
I've
e-mailed them for a quote, as their on-line store implies
world-wide
shipping, so we'll see what transpires. I must say that they
are the
coolest *looking* drivers around, with those big alloy cones!

I think the Tumults are more impressive but the AV15s are
certainly awe inspiring! During the first preorder (over a year
ago) the drivers came with a logo on the cone by default. You
may have to specify no logo. Stryke is essentially a one man
shop (John E. Janowitz). I think his wife just had a baby so he
may be somewhat tied up. His phone is 920-469-9198 if all else
fails. There's also a Stryke web forum.
http://forum.stryke.com/

"Stewart Pinkerton" wrote in message
...
I'd like to, but I don't know where to look!

Two pages of gallery pictures here with links for construction
info, frequency response measurements, etc.
https://home.comcast.net/~ttriff//page2IB-Gallery.html
https://home.comcast.net/~ttriff//page3IB-Gallery2.html

IB faq
https://home.comcast.net/~ttriff/

IB forum with ~22 pages of archives
http://f20.parsimony.net/forum36475/

On Fri, 26 Dec 2003 16:37:33 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
I'd like to, but I don't know where to look!

Two pages of gallery pictures here with links for construction
info, frequency response measurements, etc.
https://home.comcast.net/~ttriff//page2IB-Gallery.html
https://home.comcast.net/~ttriff//page3IB-Gallery2.html

IB faq
https://home.comcast.net/~ttriff/

IB forum with ~22 pages of archives
http://f20.parsimony.net/forum36475/

Thanks for the links Rusty, they have given me lots to think about!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 26 Dec 2003 16:35:18 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Thanks Rusty, I did find them after trawling the Stryke site.
I've
e-mailed them for a quote, as their on-line store implies
world-wide
shipping, so we'll see what transpires. I must say that they
are the
coolest *looking* drivers around, with those big alloy cones!

I think the Tumults are more impressive but the AV15s are
certainly awe inspiring! During the first preorder (over a year
ago) the drivers came with a logo on the cone by default. You
may have to specify no logo. Stryke is essentially a one man
shop (John E. Janowitz). I think his wife just had a baby so he
may be somewhat tied up. His phone is 920-469-9198 if all else
fails. There's also a Stryke web forum.
http://forum.stryke.com/

Thanks for that, Rusty. I must say, the recent discussions on the
Stryke forum are *not* encouraging to a potential purchaser!

I appreciate the problems if he's a 'one man band' and a new dad, but
at the end of the day I'll need products, not promises............
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 26 Dec 2003 15:17:13 +0100, Peter Larsen
wrote:

Stewart Pinkerton wrote:

Nobody seem to worry about air distortion ...

Could you give me a pointer to such a site? It's the idea of a *big*
hole in the ceiling that is caused WAF problems.

http://t-3.cc/users/audioworx/page13-12Shiva1.html

- a subpage of http://www.klone-audio.com/ - 12 large bass units firing
into a box with an estimated 12 by 12 inch opening into the listening
room.

Very impressive! Especially considering the ratio of driver area to
throat area.

For a more practical implementation of using multiple loudspeakers one
should in my opinion think differently. I would arrange a row of
loudspeakers on the loft in each side of the room and let the sound
enter the room via a long slit near the ceiling/wall junction. It would
still be possible to mount the loudspeakers vertically for longevity
(playing "downwards-sideways" into the slit) and it could be implemented
very discreetly. It will also provide a superiour coupling to the room.

A slit is certainly an option in my room, although I might have to
write my own modelling program! :-(

Peerless has a 10" sub-bass that looks about right if used in multiples.

At the moment, a pair of Adire Tempests looks to be the most likely
solution.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Stewart Pinkerton" wrote in message
...
On Fri, 26 Dec 2003 16:35:18 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
Thanks Rusty, I did find them after trawling the Stryke site.
I've
e-mailed them for a quote, as their on-line store implies
world-wide
shipping, so we'll see what transpires. I must say that they
are the
coolest *looking* drivers around, with those big alloy cones!

I think the Tumults are more impressive but the AV15s are
certainly awe inspiring! During the first preorder (over a year
ago) the drivers came with a logo on the cone by default. You
may have to specify no logo. Stryke is essentially a one man
shop (John E. Janowitz). I think his wife just had a baby so he
may be somewhat tied up. His phone is 920-469-9198 if all else
fails. There's also a Stryke web forum.
http://forum.stryke.com/

Thanks for that, Rusty. I must say, the recent discussions on the
Stryke forum are *not* encouraging to a potential purchaser!

I appreciate the problems if he's a 'one man band' and a new dad, but
at the end of the day I'll need products, not promises............
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Keep us informed on the project and it's results.

I'm planning a project with a single Shiva in a ported box of either 3.6 or
4.8 cu ft. f3 predictions are 25 and 21 Hz, respectively.

Leaning towards the smaller box for WAF nad with room gain it should get to
at least 20 Hz in the room it will be used in.

"Stewart Pinkerton" wrote in message
...
I appreciate the problems if he's a 'one man band' and a new
dad, but
at the end of the day I'll need products, not
promises............

I've been absent from the forum for awhile. It does seem like
John's backed up right now but trying to work out the backlog.
Apparently Stryke will be changing it's name Jan 1st due to
trademark issues. Looks like Acoustic Elegance is the leading
candidate.

FYI, I ordered my AV15s during the first preorder back in Oct
'02. I believe John ordered 500 AV15s from TC Sounds with the
intent to have several hundred left over to keep in stock. TC
Sounds messed up the voice coils (single 4 ohm instead of dual 2
ohm) which delayed shipments until Jan '03. By the time they
shipped John had sold out of all the drivers! Since then Kyle at
www.acoustic-visions.com has been keeping drivers in stock but
they're currently out due to waiting on the new design (dual
spider) but Kyle won't ship outside USA.

If you can handle the wait and get the UK shipping worked out the
AV15 are certainly worth it. If not, go for the Tempest. A 3x2
array of Tempests will be as good as four AV15s or three Tumults


I previously had a Velodyne F1800R and thought it was king. The
IB wipes the floor with it in every way...including cost. I had
planned on performing a level matched DBT but there was no need.
The F1800 now sits behind the computer.

Stewart Pinkerton wrote:

A slit is certainly an option in my room, although I might have to
write my own modelling program! :-(

Model, why? - ah well, one item of horn modelling software does exist
"out there", I have it somewhere on some harddisk.

Peerless has a 10" sub-bass that looks about right if used in multiples.

If I wanted to feed an elongated opening, then doing it with a line of
units comes to mind.

At the moment, a pair of Adire Tempests looks to be the most likely
solution.

Freehand a manifold, i. e. a conical horn (x), as the adapter between
the unit and the slit. Conical horns are wonderfully simple: the faster
they expand the higher their range. They also have the advantage of low
distortion due to the fast initial expansion. Remember however to also
load the other side of the membrane, at a wild guess and without
checking anything a 5 cubic feet box comes to mind, possibly 7, this to
minimize equal order distortion and to provide some driver protection.

No warranty of any kind, suggested only for those who can freehand the
amount of garlic and curry .....

Stewart Pinkerton | Music is Art - Audio is Engineering

(x) From the unit you make a transition to the slit width, 3" comes to
mind, and then you let the horn expand in one plane only horisontally on
the floor of the loft and then make a 90 degree down turn into the slit.
It is very easy to brace such a flat structure with dividers to ensure
that it is suitably rigid. The slit area should not be smaller than the
cone area, for a "seat of the pants" design guide I'd aim for two to
three times the cone area and use a fairly rapid expansion of the
conical "hornifold".

Kind regards

Peter Larsen

--
************************************************** *************
* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** *******

On Sat, 27 Dec 2003 11:23:09 +0100, Peter Larsen
wrote:

Stewart Pinkerton wrote:

A slit is certainly an option in my room, although I might have to
write my own modelling program! :-(

Model, why? - ah well, one item of horn modelling software does exist
"out there", I have it somewhere on some harddisk.

Peerless has a 10" sub-bass that looks about right if used in multiples.

If I wanted to feed an elongated opening, then doing it with a line of
units comes to mind.

I'm looking at the subwoofer bottom line of Euros per litre! :-)

A dozen Peerless units doesn't cost out so well as a couple of
Tempests, or especially Stryke AV15s.

At the moment, a pair of Adire Tempests looks to be the most likely
solution.

Freehand a manifold, i. e. a conical horn (x), as the adapter between
the unit and the slit. Conical horns are wonderfully simple: the faster
they expand the higher their range. They also have the advantage of low
distortion due to the fast initial expansion.

This doesn't make sense to me, as there is no horn expansion if the
slit is the same area as the driver Sd, as you suggest below.

Remember however to also
load the other side of the membrane, at a wild guess and without
checking anything a 5 cubic feet box comes to mind, possibly 7, this to
minimize equal order distortion and to provide some driver protection.

Yes, this is one of my concerns.

No warranty of any kind, suggested only for those who can freehand the
amount of garlic and curry .....

Always!

Tonight of course, it'll be turkey curry........... :-)

(x) From the unit you make a transition to the slit width, 3" comes to
mind, and then you let the horn expand in one plane only horisontally on
the floor of the loft and then make a 90 degree down turn into the slit.
It is very easy to brace such a flat structure with dividers to ensure
that it is suitably rigid. The slit area should not be smaller than the
cone area, for a "seat of the pants" design guide I'd aim for two to
three times the cone area and use a fairly rapid expansion of the
conical "hornifold".

I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two
drivers (for improved WAF....) , expanding into the 1/8 space of the
room corner. As you say, there may need to be a back box to equalise
cone loading.

OTOH, since I'm staying well below Xmax for normal operation, perhaps
this is all a little paranoid! OTGH, design time costs me nothing, so
why not do it right first time..................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:

Freehand a manifold, i. e. a conical horn (x), as the adapter between
the unit and the slit. Conical horns are wonderfully simple: the faster
they expand the higher their range. They also have the advantage of low
distortion due to the fast initial expansion.

This doesn't make sense to me, as there is no horn expansion if the
slit is the same area as the driver Sd, as you suggest below.

Expansion prevents too many parallel walls. If you go for the suggested
model with 3" as the smallest dimension of manifold and slit then you
have to make some kind of a transition from the 13" membrane. This is
not about midrange, so doing it the crude way comes to mind, i. e.
starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10
inches initial area. Even to simply enter the room with the membrane
area will then require expansion.

I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two
drivers (for improved WAF....) , expanding into the 1/8 space of the
room corner. As you say, there may need to be a back box to equalise
cone loading.

Ah, going to the room corner is a mitigating factor because it allows
you to use the corner as an extension of the conical horn in the
manifold. And with an "L" shaped slit in the ceiling in the corner it
ought to be possible to make it a lot more compact than I had first
thougth.

OTOH, since I'm staying well below Xmax for normal operation, perhaps
this is all a little paranoid! OTGH, design time costs me nothing, so
why not do it right first time..................

Minimizing distortion and getting an optimum coupling to the room are
worthwhile aims and probably pre-requites for a system that is supposed
to be able to play well in trippel forte as well as in the way more
difficult trippel piano.

Try searching for hornresp ... it may be possible to express this as a
conical horn it can understand, in which case it could be helpful to try
modelling in it.

Stewart Pinkerton | Music is Art - Audio is Engineering


Kind regards

Peter Larsen

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"Stewart Pinkerton" wrote in message
...
OTOH, since I'm staying well below Xmax for normal operation,
perhaps
this is all a little paranoid! OTGH, design time costs me
nothing, so
why not do it right first time..................

If your house is drywall/sheetrock just go for it. Cheap and
easy to patch

Also, if you didn't see there's a set a photos on the first
gallery page of the IB site where someone built a cloth covered
grill for a white ceiling. I would have made it flush with the
ceiling...maybe something else to think about for wife
acceptance.

Rusty Boudreaux wrote:

If your house is drywall/sheetrock just go for it. Cheap and
easy to patch

The nice thing about the slit is that one can install lights in it and a
bit of screen in front of it and pretend that it is mood lights for the
room.


--
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* \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// *
* \\\\\\\ My site is at: http://www.muyiovatki.dk /////// *
************************************************** *******

On Sat, 27 Dec 2003 22:18:15 -0600, "Rusty Boudreaux"
wrote:

"Stewart Pinkerton" wrote in message
...
OTOH, since I'm staying well below Xmax for normal operation,
perhaps
this is all a little paranoid! OTGH, design time costs me
nothing, so
why not do it right first time..................

If your house is drywall/sheetrock just go for it. Cheap and
easy to patch

Nope, it has 13" thick brick/block walls, only the ceiling is
conventional wooden joists and plasterboard (sheetrock to you).

Also, if you didn't see there's a set a photos on the first
gallery page of the IB site where someone built a cloth covered
grill for a white ceiling. I would have made it flush with the
ceiling...maybe something else to think about for wife
acceptance.

Yes, I've seen that shot, and I might get away with something similar
to that, or two or three of the HVAC vents someone else used. My
concern with the cloth approach is that a Vd of 5 litres at 20-50Hz is
likely to cause some pretty visible flapping!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Sat, 27 Dec 2003 19:03:59 +0100, Peter Larsen
wrote:

Stewart Pinkerton wrote:

Freehand a manifold, i. e. a conical horn (x), as the adapter between
the unit and the slit. Conical horns are wonderfully simple: the faster
they expand the higher their range. They also have the advantage of low
distortion due to the fast initial expansion.

This doesn't make sense to me, as there is no horn expansion if the
slit is the same area as the driver Sd, as you suggest below.

Expansion prevents too many parallel walls.

Which are completely irrelevant in a sub. In fact, a cube is the
*best* enclosure shape for a sealed-box sub, as it has maxium wall
rigidity for any given volume and material.

If you go for the suggested
model with 3" as the smallest dimension of manifold and slit then you
have to make some kind of a transition from the 13" membrane. This is
not about midrange, so doing it the crude way comes to mind, i. e.
starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10
inches initial area. Even to simply enter the room with the membrane
area will then require expansion.

You can however transit directly from a 13" circle to a 3" x 44" slit
(to maintain equal areas) without any expansion whatever, simply by
making a double-tapered box, so why bother with an intermediate
constriction? BTW, such a manifold box will have minimal resonance
problems due to the heavy taper of the box sides, so it's also a
mechanically sound design not requiring heroic wall thickness.

I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two
drivers (for improved WAF....) , expanding into the 1/8 space of the
room corner. As you say, there may need to be a back box to equalise
cone loading.

Ah, going to the room corner is a mitigating factor because it allows
you to use the corner as an extension of the conical horn in the
manifold. And with an "L" shaped slit in the ceiling in the corner it
ought to be possible to make it a lot more compact than I had first
thougth.

I currently favour a 10" square aperture, which is reasonably discreet
and gives a 3:1 area compression from a pair of 15" drivers. Might
have to be a foot square to allow for grille solidity.

OTOH, since I'm staying well below Xmax for normal operation, perhaps
this is all a little paranoid! OTGH, design time costs me nothing, so
why not do it right first time..................

Minimizing distortion and getting an optimum coupling to the room are
worthwhile aims and probably pre-requites for a system that is supposed
to be able to play well in trippel forte as well as in the way more
difficult trippel piano.

Indeed so, hence lots of thinking before firing up the jigsaw!

Try searching for hornresp ... it may be possible to express this as a
conical horn it can understand, in which case it could be helpful to try
modelling in it.

Aside from the basic expansion into 1/8 space given by corner
mounting, I have no intention of getting into the multitudinous
problems of horns!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Sorry guys - I missed the start of this thread, and I've been watching ever
since to find out just what is an "IB"?

Tony (remove the "_" to reply by email)

(Stewart Pinkerton)
wrote:

I'll just give a few details about exhaust opening area. My entrance to the
listening room is a simple hole int he floor of 14.5 and 33-inches; in other
words joist width and not quite 3-feet long.

There are 2 basic artifacts (maybe advantages dependibg on your outlook). First
the air trapped in the plenum (containing 8 23mm 15-inch woofers in a floor to
ceiling basement enclosure) gets added to the mass of the system giving a set
of drivers with a 30 Hz Free air resonance at system resonance of 21 Hz when
deployed like this. Accordingly I then need 18 dB of EQ at 12 Hz to makle the
system flat to 12 Hz at 90 dB SPL.

The other effect is a 70 Hz resonance notch apparently caused by the distance
between the top and bottom woofer centers. But the system is rolling off
naturally at 70 Hz anyway so this just sharpens the low pass function.

As for driver piston area and opening area it doesn't seem to be an issue.with
a 2:1 piston area to chute opening ratio. I know of a few other systems where
fairly small chute openings didn't seem to impair in-room response.

I think of such a system as more of a slot-load than a bandpass; but it could
be modeled as a bandpass with a huge rear chamber and a small front with a
short port. Perhaps slot-load is just a special case of bandpass.

On Mon, 29 Dec 2003 01:40:54 +1000, Tony Roe
wrote:

Sorry guys - I missed the start of this thread, and I've been watching ever
since to find out just what is an "IB"?

Infinite Baffle. Eithee a *very* large plate to which the drivers are
attached, or more reasonably, fitting the drivers in the wall between
two rooms.
--

Stewart Pinkerton | Music is Art - Audio is Engineering