I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim

On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

d

_____________________________

http://www.pearce.uk.com

On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

d

_____________________________

http://www.pearce.uk.com

On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

d

_____________________________

http://www.pearce.uk.com

"Don Pearce" wrote in message
...
On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In
the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of
the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length
of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the
whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma -
the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned
down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.


Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?

"Don Pearce" wrote in message
...
On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In
the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of
the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length
of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the
whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma -
the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned
down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.


Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?

"Don Pearce" wrote in message
...
On Sun, 21 Dec 2003 08:50:05 -0600, "Jim Ranieri"
wrote:

I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In
the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of
the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length
of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the
whole
'standing wave' thing go out the window at other frequencies?

If one uses a single full range driver - let's say a Fostex 6.5" Sigma -
the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned
down
to 30 Hz that our Fostex speaker is only good down to 51?

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

Thanks,
Jim


The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line - and it
will be in phase so helping out the main wave. As you go higher than
30Hz, the absorption of the filling improves, so less of the back wave
is available at the vent, and the whole thing looks a little more like
an infinite baffle.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.


Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?

On Sun, 21 Dec 2003 11:32:32 -0600, "Jim Ranieri"
wrote:

Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?


We don't discuss this particular company in polite society. And in
answer to your final question - no.

d

_____________________________

http://www.pearce.uk.com

On Sun, 21 Dec 2003 11:32:32 -0600, "Jim Ranieri"
wrote:

Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?


We don't discuss this particular company in polite society. And in
answer to your final question - no.

d

_____________________________

http://www.pearce.uk.com

On Sun, 21 Dec 2003 11:32:32 -0600, "Jim Ranieri"
wrote:

Thanks for the reply. Now, I read about an interesting (to me anyway) twist
on the whole t-line concept: a well known manufacturer of popular speakers
and clock radios patented a t-line configuration that is 1/4 wavelength on
the front of the cone, and a second tube on the back of the cone that is 1/3
the length of the front tube. The vent openings are spaced a set distance
apart and apparently reinforce each other at certain frequencies.
Interestingly, the tubes are hard surfaced and unfilled. Does the physics
behind this concept seem sound?


We don't discuss this particular company in polite society. And in
answer to your final question - no.

d

_____________________________

http://www.pearce.uk.com

Don Pearce wrote:

The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line

It is possible to build it closed, it will still have its main virtue of
being the only cabinet to lower Fs. I have heard such a pair - wall
integrated - with Altec 15" studio bass, remarkably capable.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And preferably sheeps wool according to the builders lore I am
acquainted with.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

http://www.pearce.uk.com


Kind regards

Peter Larsen

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

Don Pearce wrote:

The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line

It is possible to build it closed, it will still have its main virtue of
being the only cabinet to lower Fs. I have heard such a pair - wall
integrated - with Altec 15" studio bass, remarkably capable.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And preferably sheeps wool according to the builders lore I am
acquainted with.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

http://www.pearce.uk.com


Kind regards

Peter Larsen

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

Don Pearce wrote:

The idea of a transmission line speaker is that as far as possible all
the power from the back of the cone is absorbed along the length of
the line. In practice, what you try and do is gain just a little extra
bass by allowing some of that 30Hz to leak through the line

It is possible to build it closed, it will still have its main virtue of
being the only cabinet to lower Fs. I have heard such a pair - wall
integrated - with Altec 15" studio bass, remarkably capable.

So the big adjustable in a TL is the filling. You have to get that
dead right to optimise the bass response, too little and it will boom,
too much and the bass will be light.

And preferably sheeps wool according to the builders lore I am
acquainted with.

And of course the wavelength is reduced in the filled medium, so the
box doesn't need to be quite as long as you think.

http://www.pearce.uk.com


Kind regards

Peter Larsen

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

In article , "Jim Ranieri" wrote:
I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

There is a range where the bass control is usefull. Stuffing a line also changes the effective
length. You don't try to get a low end by length alone.

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

A line or any box, is made for the driver. Not the other way around.
You tune the line for the drivers fs.

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

There are guidelines and even formulas for transmission lines, but
it is still mystical as far as I'm concerned. If you use the guidelines,
you should end up with something usefull.

greg

In article , "Jim Ranieri" wrote:
I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

There is a range where the bass control is usefull. Stuffing a line also changes the effective
length. You don't try to get a low end by length alone.

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

A line or any box, is made for the driver. Not the other way around.
You tune the line for the drivers fs.

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

There are guidelines and even formulas for transmission lines, but
it is still mystical as far as I'm concerned. If you use the guidelines,
you should end up with something usefull.

greg

In article , "Jim Ranieri" wrote:
I'm considering building a transmission line speaker and will be ordering
The Loudspeaker Design Cookbook and Designing, Building... by Weems. In the
meantime, I have a couple elementary questions about the technology.

(preface all the following with "As I understand it...")

A t-line or other quarter wave speaker requires a tube 1/4 the length of the
lowest frequency you are trying to get. So, if we want 30 Hz, that
correlates to a wavelngth of about 11m - so we should have a tube length of
about 2.75m. Fine. We're good at 30Hz, now what about 50Hz? Does the whole
'standing wave' thing go out the window at other frequencies?

There is a range where the bass control is usefull. Stuffing a line also changes the effective
length. You don't try to get a low end by length alone.

If one uses a single full range driver - let's say a Fostex 6.5" Sigma - the
FS (?) is listed at 51Hz. Does that mean that even with our pipe tuned down
to 30 Hz that our Fostex speaker is only good down to 51?

A line or any box, is made for the driver. Not the other way around.
You tune the line for the drivers fs.

The speaker is listed as having a Vas(?) of 23.7 liters. How should this
number relate to the volume of the t-line tube (if at all)?

There are guidelines and even formulas for transmission lines, but
it is still mystical as far as I'm concerned. If you use the guidelines,
you should end up with something usefull.

greg

Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com

Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com

Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com

"MJKing57" wrote in message
...
Hi Jim,

If you would like to read a little bit more on TL design, you might want
to
take a look at my website. I have put together some theory on TL design
that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your
choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and
should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing.
Fiber
stuffing does damp the higher resonances but does not change the speed of
sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same
frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only
valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com


That's an excellent resource - I've bookmarked it.

Thanks,
Jim

"MJKing57" wrote in message
...
Hi Jim,

If you would like to read a little bit more on TL design, you might want
to
take a look at my website. I have put together some theory on TL design
that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your
choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and
should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing.
Fiber
stuffing does damp the higher resonances but does not change the speed of
sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same
frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only
valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com


That's an excellent resource - I've bookmarked it.

Thanks,
Jim

"MJKing57" wrote in message
...
Hi Jim,

If you would like to read a little bit more on TL design, you might want
to
take a look at my website. I have put together some theory on TL design
that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your
choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and
should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing.
Fiber
stuffing does damp the higher resonances but does not change the speed of
sound
by 40 to 50% as I have seen claimed by some builders. If they removed the
stuffing and remeasured, I think that they would find almost the same
frequency
for the line's resonance.

Second, the standard equation for the line's frequency f = c/4L is only
valid
for straight uniform cross-sections. If you taper the line is needs to be
shorter. My alignment tables show this very well.

A few more old wives tales are also corrected.

Hope that helps,

Martin J. King

Quarter Wavelength Loudspeaker Design
www.quarter-wave.com


That's an excellent resource - I've bookmarked it.

Thanks,
Jim

In article , (MJKing57) wrote:
Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the

I had said that stuffing changes the line length requirment. Well it does do that. Many
years ago I started making some tests to find delays by direct measurment of the wavefront.
I got delays up to 35%, but that was extreme stuffing, no where near the suggested typical
stuffing rates. Something like 2.6 lbs per cu ft. vs .5 lb typical. I also was looking for a change
in speed vs frequency. I couldnot find any evidence of this as suggested by an earlier paper on the
subject. There was also something about a delay of change in speed with an applied burst, I found
none of this also. I'll have to examine that website when I get a chance.

greg

In article , (MJKing57) wrote:
Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the

I had said that stuffing changes the line length requirment. Well it does do that. Many
years ago I started making some tests to find delays by direct measurment of the wavefront.
I got delays up to 35%, but that was extreme stuffing, no where near the suggested typical
stuffing rates. Something like 2.6 lbs per cu ft. vs .5 lb typical. I also was looking for a change
in speed vs frequency. I couldnot find any evidence of this as suggested by an earlier paper on the
subject. There was also something about a delay of change in speed with an applied burst, I found
none of this also. I'll have to examine that website when I get a chance.

greg

In article , (MJKing57) wrote:
Hi Jim,

If you would like to read a little bit more on TL design, you might want to
take a look at my website. I have put together some theory on TL design that
includes computer simulations and correlating measurements. There is free
software and alignment tables to help design a TL enclosure for your choice of
driver.

Several of the traditional rules of thumb are shown to be inaccurate and should
not be used.

First, the speed of sound is not significantly reduced by fiber stuffing. Fiber
stuffing does damp the higher resonances but does not change the speed of sound
by 40 to 50% as I have seen claimed by some builders. If they removed the

I had said that stuffing changes the line length requirment. Well it does do that. Many
years ago I started making some tests to find delays by direct measurment of the wavefront.
I got delays up to 35%, but that was extreme stuffing, no where near the suggested typical
stuffing rates. Something like 2.6 lbs per cu ft. vs .5 lb typical. I also was looking for a change
in speed vs frequency. I couldnot find any evidence of this as suggested by an earlier paper on the
subject. There was also something about a delay of change in speed with an applied burst, I found
none of this also. I'll have to examine that website when I get a chance.

greg