Reading that drive units hardly move in a rear horn speaker- I guess this means much less distortion in the bass region- just wondering if this is the same for transmission line designs?
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Depends on the nature of the transmission lines... in the terms narrowest sense it is an aperiodic box which will have similar excursion as sealed, in its broadest sense a horn is a TL, and TLs include everything in between
dave
dave
Just from a sheer engineering level, I would imagine that at specific resonance points that when the line is vibrating at its fundamental (or multiples thereof), there would be very little excursion due to the backpressure within the box?
L
L
That is one of the concepts of a well tuning taditional TL... the primamry resonance reduces the driver's fundemental resonance.
dave
dave
software can examine - here's a ridiculously large BIB pipe-horn type simulation for a Nirvana 10" with ~50Hz resonance - note the excursion in-band is lowest where the impedance nulls occur and power handling at 45Hz is less than one watt for its specified 1mm xmax. For me it would make more sense to have the Nirvana in a 75 liter Karlson coupler (where it loads better and sounds better) - then if desired, augment the bottom with a reasonable size sealed box woofer.
An externally hosted image should be here but it was not working when we last tested it.
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I've heard alot of forum talk about the Karlson design lately. It must be quite good. Wish I could hear one.
Hi,
That was untrue for any rear-loaded horns I encountered, be they JBL Scoop type PA systems, Hedlund Horns with Lowthers or AER's, LBH's and Beauhorns.
It is true (or more true) for front loaded bass horns that operate the bass driver in a small sealed chamber (common for big PA Bass horns), however such systems often raise the in system resonance much so the resulting horn does not play as low when stacked as one would expect.
TL's and related structures will have resonances (just like a bass reflex box) where they will cause a reduction (often very substantial) of cone motion, at other frequencies no such action takes place.
Indeed I find that I get most mileage from analysing so-called TL's as atypical reflex box with a very low tuning via a large cross-section port and small actual box, plus the various parasitic resonances the long and often folded port causes.
Doing this in simulation seems to fit the actual measured results better than using classic TL Theory.
Ciao T
That was untrue for any rear-loaded horns I encountered, be they JBL Scoop type PA systems, Hedlund Horns with Lowthers or AER's, LBH's and Beauhorns.
It is true (or more true) for front loaded bass horns that operate the bass driver in a small sealed chamber (common for big PA Bass horns), however such systems often raise the in system resonance much so the resulting horn does not play as low when stacked as one would expect.
TL's and related structures will have resonances (just like a bass reflex box) where they will cause a reduction (often very substantial) of cone motion, at other frequencies no such action takes place.
Indeed I find that I get most mileage from analysing so-called TL's as atypical reflex box with a very low tuning via a large cross-section port and small actual box, plus the various parasitic resonances the long and often folded port causes.
Doing this in simulation seems to fit the actual measured results better than using classic TL Theory.
Ciao T
re:'analysing so-called TL's as atypical reflex box with a very low tuning via a large cross-section port and small actual box' - interesting, Thorsten. So, what roughly proportion of the TL volume would you use as the 'box', and what proportion as the 'port'? or is it an 'it depends' answer? 🙂
Hi,
It depends is inedded the answer. Usually the section to the first fold.
Note, this analysis is best applied to actual, practicalnd what I call "foreshortened lines" True transmission lines exist and can operate according to the formal theory, just very few people seem to build any.
I hit on that other model while trying to get sensible results from reverse engineering some commercial TL Speakers that had a by far to small size and short line to operate as transmission line at frequencies as low as they did.
While build like TL's, they basically fail to operate as such, they are simply reflex boxes with a very large amount of space dedicated to the port.
Ciao T
It depends is inedded the answer. Usually the section to the first fold.
Note, this analysis is best applied to actual, practicalnd what I call "foreshortened lines" True transmission lines exist and can operate according to the formal theory, just very few people seem to build any.
I hit on that other model while trying to get sensible results from reverse engineering some commercial TL Speakers that had a by far to small size and short line to operate as transmission line at frequencies as low as they did.
While build like TL's, they basically fail to operate as such, they are simply reflex boxes with a very large amount of space dedicated to the port.
Ciao T
Classic TL theory was toast 10+ years ago when King & Augspurger introed their TL modeling software.
dave
Hi,
Sure. I used Mark's software in the process (among others).
I guess now we need to work on:
"Are foreshortened TL's BR Boxes with a huge multiresonant port (I can certainly get a really good Impedance and acceptable SPL fit using just unibox!) or are they compromised TL's?"
My point is:
"They are BR's, as the operation is essentially that of a Helmholz resonator, if one of uncommon physical structure!"
I have used to that to design a fairly compact monitor with uncommonly low LF extension. It's acoustic system is maybe the ultimate "foreshortened TL".
The key problem is that it most "reflex" boxes compromise on both vent length and cross-section (just try to tune a 30 Liter Box fitted with a serious 10" Driver to 25Hz and keep the airspeed low enough to cause chuffing at 600W peak input...), so they usually do not have the "TL Bass" (in the positive sense of the word).
BTW, here one to boil your noodles.
Is the attached a TL or a Reflex Box? Driver is 10" and the width is around 10" as well, so the exit is around 21cm X 5cm.
"I guess I'll leave that question to the experts,
assuming that there are some out there.
they're probably alone, solitaire."
(From P.M. Dawn - Set Adrift On Memory Bliss)
Ciao T
from the Album:
Of the Heart, of the Soul and of the Cross: The Utopian Experience
P.M. Dawn - Set Adrift On Memory Bliss
check link for songfacts,
[extra points to anoyone who used to have (or still has) the hots for Christina Applegate]
The camera pans the cocktail glass,
behind a blind of plastic plants;
I found the lady with the fat diamond ring.
then you know I can't remember a damn thing.
I think it's one of those de ja vu things,
or a dream that's tryin' to tell me something.
Or will I ever stop thinkin' about it.
I don't know, I doubt it.
Subterranean by design,
I wonder what I would find if I met you,
let my eyes caress you,
until I meet the thought of Missess Princess Who?
Often wonder what makes her work.
I guess I'll leave that question to the experts,
assuming that there are some out there.
they're probably alone, solitaire.
I can remember when I caught up
with a pastime intimate friend.
She said, "Bet you're probably gonna say I look lovely,
but you probably don't think nothin' of me."
She was right, though, I can't lie.
She's just one of those corners in my mind,
and I just put her right back with the rest.
That's the way it goes, I guess.
Baby you send me
Set adrift on memory bliss of you
Careless whisper from a careless man,
a neutron dance for a neutron fan;
marionette strings are dangerous things,
I thought of all the trouble they bring.
An eye for an eye, a spy for a spy,
rubber bands expand in a frustrating sigh.
Tell me that she's not dreaming.
She's got an ace in the hole,
it doesn't have meaning.
Reality used to be a friend of mine,
'cause complete control, I don't take too kind.
Christina Applegate, you gotta put me on.
Guess who's piece of the cake is Jack gone?
She broke her wishbone and wished for a sign.
I told her whispers in my heart were fine.
what did she think she could do?
I feel for her, I really do.
The next day I had the ring finger on her hand,
I wanted her to be a big PM Dawn fan,
but I had to put her right back with the rest.
That's the way it goes, I guess.
Baby you send me...
Set adrift on memory bliss of you
Sure. I used Mark's software in the process (among others).
I guess now we need to work on:
"Are foreshortened TL's BR Boxes with a huge multiresonant port (I can certainly get a really good Impedance and acceptable SPL fit using just unibox!) or are they compromised TL's?"
My point is:
"They are BR's, as the operation is essentially that of a Helmholz resonator, if one of uncommon physical structure!"
I have used to that to design a fairly compact monitor with uncommonly low LF extension. It's acoustic system is maybe the ultimate "foreshortened TL".
The key problem is that it most "reflex" boxes compromise on both vent length and cross-section (just try to tune a 30 Liter Box fitted with a serious 10" Driver to 25Hz and keep the airspeed low enough to cause chuffing at 600W peak input...), so they usually do not have the "TL Bass" (in the positive sense of the word).
BTW, here one to boil your noodles.
Is the attached a TL or a Reflex Box? Driver is 10" and the width is around 10" as well, so the exit is around 21cm X 5cm.
"I guess I'll leave that question to the experts,
assuming that there are some out there.
they're probably alone, solitaire."
(From P.M. Dawn - Set Adrift On Memory Bliss)
Ciao T
from the Album:
Of the Heart, of the Soul and of the Cross: The Utopian Experience
P.M. Dawn - Set Adrift On Memory Bliss
check link for songfacts,
[extra points to anoyone who used to have (or still has) the hots for Christina Applegate]
The camera pans the cocktail glass,
behind a blind of plastic plants;
I found the lady with the fat diamond ring.
then you know I can't remember a damn thing.
I think it's one of those de ja vu things,
or a dream that's tryin' to tell me something.
Or will I ever stop thinkin' about it.
I don't know, I doubt it.
Subterranean by design,
I wonder what I would find if I met you,
let my eyes caress you,
until I meet the thought of Missess Princess Who?
Often wonder what makes her work.
I guess I'll leave that question to the experts,
assuming that there are some out there.
they're probably alone, solitaire.
I can remember when I caught up
with a pastime intimate friend.
She said, "Bet you're probably gonna say I look lovely,
but you probably don't think nothin' of me."
She was right, though, I can't lie.
She's just one of those corners in my mind,
and I just put her right back with the rest.
That's the way it goes, I guess.
Baby you send me
Set adrift on memory bliss of you
Careless whisper from a careless man,
a neutron dance for a neutron fan;
marionette strings are dangerous things,
I thought of all the trouble they bring.
An eye for an eye, a spy for a spy,
rubber bands expand in a frustrating sigh.
Tell me that she's not dreaming.
She's got an ace in the hole,
it doesn't have meaning.
Reality used to be a friend of mine,
'cause complete control, I don't take too kind.
Christina Applegate, you gotta put me on.
Guess who's piece of the cake is Jack gone?
She broke her wishbone and wished for a sign.
I told her whispers in my heart were fine.
what did she think she could do?
I feel for her, I really do.
The next day I had the ring finger on her hand,
I wanted her to be a big PM Dawn fan,
but I had to put her right back with the rest.
That's the way it goes, I guess.
Baby you send me...
Set adrift on memory bliss of you
Attachments
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Just reading up on aperoidic enclosures and compact TL's/ horns. Thinking to make a tiny AP or TL enclosure using a couple of small full rangers per box and its v interesting reading all the posts.
Thorsten,
The ANSYS plots in Martin's ML-TQWT paper clearly shows a difference between BR & MLTL once sufficient length is introduced. In the transition region things are much more nebulous. Fortunately when using the MJK software one doesn't have to worry about what one should call the box, you just need to observe the results. It is equally capable of modeling a BR (including the detail of where the port is), to an MLTL or a horn. It has really opened up the (multidimensional) space of possible loudspeaker enclosures to exploration. One area where it could be extended thou, is what happens when you have very high densities of damping (ie aperiodic porting)
dave
The ANSYS plots in Martin's ML-TQWT paper clearly shows a difference between BR & MLTL once sufficient length is introduced. In the transition region things are much more nebulous. Fortunately when using the MJK software one doesn't have to worry about what one should call the box, you just need to observe the results. It is equally capable of modeling a BR (including the detail of where the port is), to an MLTL or a horn. It has really opened up the (multidimensional) space of possible loudspeaker enclosures to exploration. One area where it could be extended thou, is what happens when you have very high densities of damping (ie aperiodic porting)
dave
Thorsten, what's a ' multiresonant port'? - does this refer to 'the various parasitic resonances the long and often folded port causes' or something else? (I see it's a quote, but not sure where it's from..??)
Hi,
Exactly that:
'the various parasitic resonances the long and often folded port causes'
Ciao T
Exactly that:
'the various parasitic resonances the long and often folded port causes'
Ciao T
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