rick57 said:
Greets!
While all box alignments are technically BP's (including OB, horn, etc.), the term BP is used to describe a compression loaded driver, ergo DBRs are not BPs, but two resonant chambers in tandem.
By careful design.
If designed/tweaked properly, there is no need for BSC. Indeed, it's what the BLH is for.
Hmm, I see I forgot to mention that all the dims are inside (i.d.).
Yes. It's a simple rectangular reflex cab, ergo no compression ratio per se. CSA = cross sectional area, i.e. width x depth.
Well, height (L) is specified as 31.375" and suggested width as 32.1875", so this would normally be the baffle size, but the vent is full width and 19.875" high, so the baffle would only be 12.3125", too short to mount a 15" driver (a point I obviously didn't check and my simple Excel SS isn't programmed to check), ergo it will need to be long enough to mount the driver and the sides of the cab will have to be cut out to make up the difference in lost vent area. If the baffle's 16" high, leaving a 15.375" high vent, then each side panel will need to be cut out ~4.75". That, or re-shape the cab:
L = 31.375"
W = 41.625"
D = 15.375"
or:
L = 31.375"
W x D = whatever 'floats yer boat', leave the bottom open and space it off the floor till it sounds best to you.
I haven't posted a BLH sim, only a DBR, which defines blue line = driver response, red = vent response. The C40 BLH link is an actual measurement.
There are, but I worked hard n' long to learn horn design and while I've parted with quite a bit of it answering folk's Qs on the various forums, I draw the line at publishing a 'horn design for dummies' tutorial as so many have asked me and others to do.
GM
Hi GM
Thanks for your clarifications, I like the tunability of “space it off the floor till it sounds best to you”
> it's what the BLH is for.
I thought the primary attraction was: a horn with ample slam that was a little simpler to make . .
> It's a simple rectangular reflex cab
(And no internal folds?) my understanding of a scoop was from
www.diyaudio.com/forums/showthread.php?s=&postid=357993&highlight=#post357993 which IIRC was identified as a Rane)
and with corner reflectors & more bracing, but (I don’t know why) a section near the driver without expansion www.speakerplans.com/index.php?id=18superscooper
. . ie the back curved to smooth the later sound path, which I thought from their name all scoops would. .
> I worked hard n' long to learn horn design and while I've parted with quite a bit of it answering folk's Qs on the various forums, I draw the line at publishing a 'horn design for dummies' tutorial as so many have asked me and others to do.
Have any of the suggestions included that you charge for it? So your experience is shared, and you are rewarded for your effort? I’d be a likely customer . .
Cheers
Thanks for your clarifications, I like the tunability of “space it off the floor till it sounds best to you”
> it's what the BLH is for.
I thought the primary attraction was: a horn with ample slam that was a little simpler to make . .
> It's a simple rectangular reflex cab
(And no internal folds?) my understanding of a scoop was from
www.diyaudio.com/forums/showthread.php?s=&postid=357993&highlight=#post357993 which IIRC was identified as a Rane)
and with corner reflectors & more bracing, but (I don’t know why) a section near the driver without expansion www.speakerplans.com/index.php?id=18superscooper
. . ie the back curved to smooth the later sound path, which I thought from their name all scoops would. .
> I worked hard n' long to learn horn design and while I've parted with quite a bit of it answering folk's Qs on the various forums, I draw the line at publishing a 'horn design for dummies' tutorial as so many have asked me and others to do.
Have any of the suggestions included that you charge for it? So your experience is shared, and you are rewarded for your effort? I’d be a likely customer . .
Cheers
Driver Choice
I just saw the Matterhorn video (http://www.danleysoundlabs.com/matterhorn.htm) and i wonder if the driver they use in it (and the TH-50) is this one...
http://www.mtx.com/caraudio/products/subwoofers/thunder9500.cfm
Judging by the looks it could be the driver, but what do i know ;D
Strange thing, to use a car sub. I thought the sound quality of these drivers is no good, since the TS parameter difference in comparison to a normal pro woofer couldnt be bigger.
I just saw the Matterhorn video (http://www.danleysoundlabs.com/matterhorn.htm) and i wonder if the driver they use in it (and the TH-50) is this one...
http://www.mtx.com/caraudio/products/subwoofers/thunder9500.cfm
Judging by the looks it could be the driver, but what do i know ;D
Strange thing, to use a car sub. I thought the sound quality of these drivers is no good, since the TS parameter difference in comparison to a normal pro woofer couldnt be bigger.
rick57 said:
Greets!
You're welcome!
Science only takes you so far.........
No folds, it's not a BLH, merely a simple cab for you to experiment with and possibly be satisfied with its performance at some level of damping. The referenced 'scoops' are the most common type of BLH (big vent reflexes (BVR)), ergo the 'box' behind the driver is its low pass filter with the horn being its vent.
Yes, but talk's cheap and most folks won't pay a fair price. Anyway, I hope to get back into speaker building in ~2-5 yrs if my health doesn't take another nose-dive.
GM
Re: Driver Choice
Greets!
I was told it was made by them, but not whether it was a stock unit less the MTX logo or custom. Anyway, TD has a history of using Leach's math to define the right driver for the job, so I imagine it's a custom just as the LABhorn, Unity, etc., drivers are, so SQ tends to be fine regardless of its T/S specs since the horn will dramatically alter them via horn loading.
GM
MaVo said:
Greets!
I was told it was made by them, but not whether it was a stock unit less the MTX logo or custom. Anyway, TD has a history of using Leach's math to define the right driver for the job, so I imagine it's a custom just as the LABhorn, Unity, etc., drivers are, so SQ tends to be fine regardless of its T/S specs since the horn will dramatically alter them via horn loading.
GM
Hi GM
re post 186
> Science only takes you so far.........
Yes, I’m probably too inclined to try to do it all by science
> No folds, it's not a BLH, merely a simple cab for you to experiment with and possibly be satisfied with its performance at some level of damping.
So it’s a very big reflex box (nearly 12 cubic feet), non-horn-loaded, with a giant vent.
If it’s at all accurate, modelling as a reflex box with that size vent suggests a peak c. 7! db peak centred at about 65 Hz, but ‘gone’ by 100 Hz. Might still need a BS circuit, but that’s ok with me.
Certainly slam there, and an alignment Dickason didn’t mention, and I wouldn’t have imagined anything like that!
A buddy with way more knowledge than me being a devil’s advocate, threw me a little by suggesting building a flat alignment, and playing with EQ – how does boost sound vs the EQ bump being “in” the alignment?
Having the vent at the floor theoretically allows tunability of the vent opening, but fwiw Unibox predicts that increasing the already large vents make little difference to the FR . .
> The referenced 'scoops' are the most common type of BLH (big vent reflexes (BVR)), ergo the 'box' behind the driver is its low pass filter with the horn being its vent.
Mm, maybe I could add a scoop and see what it does for response . .
> most folks won't pay a fair price.
I find that almost incomprehensible, but we’re all different . .
If you wrote a guide for dummies, personally I’d pay say $40?
$40 * even 50? = . .
Just a suggestion to earn something from all your time . .
Cheers and Thanks again
re post 186
> Science only takes you so far.........
Yes, I’m probably too inclined to try to do it all by science
> No folds, it's not a BLH, merely a simple cab for you to experiment with and possibly be satisfied with its performance at some level of damping.
So it’s a very big reflex box (nearly 12 cubic feet), non-horn-loaded, with a giant vent.
If it’s at all accurate, modelling as a reflex box with that size vent suggests a peak c. 7! db peak centred at about 65 Hz, but ‘gone’ by 100 Hz. Might still need a BS circuit, but that’s ok with me.
Certainly slam there, and an alignment Dickason didn’t mention,
and I wouldn’t have imagined anything like that!A buddy with way more knowledge than me being a devil’s advocate, threw me a little by suggesting building a flat alignment, and playing with EQ – how does boost sound vs the EQ bump being “in” the alignment?
Having the vent at the floor theoretically allows tunability of the vent opening, but fwiw Unibox predicts that increasing the already large vents make little difference to the FR . .
> The referenced 'scoops' are the most common type of BLH (big vent reflexes (BVR)), ergo the 'box' behind the driver is its low pass filter with the horn being its vent.
Mm, maybe I could add a scoop and see what it does for response . .
> most folks won't pay a fair price.
I find that almost incomprehensible, but we’re all different . .
If you wrote a guide for dummies, personally I’d pay say $40?
$40 * even 50? = . .
Just a suggestion to earn something from all your time . .
Cheers and Thanks again
Hi Gregory, All
Well in this case, it is essentially a stock driver, having to design something around stock parts and all for a low volume product. I don’t expect there will be lots of Matterhorns built. It is a particularly rugged driver with parameters I could deal with for something as big as the Matterhorn thing, worked well in the TH-50 too.
If you guys are playing with Tapped horns, some one should pop for a program which will model them, like AKABAK.
I can maybe give you guys another clue or two which will help understanding how it works. As one approaches the low corner on a conventional bass horn, the horn acts more and more like a slug of air, it has mass which appears to increase as the frequency falls. In a normal horn, that reactance is adjusted by changing the “t” and ideally exactly off set by the compliance of the driver in a sealed box. With the Tapped horn, one has no rear volume so to get the lowest low corner, one needs the driver’s Fs to be somewhat above the low cutoff. For example, it wouldn’t be unusual to have an Fs of 45 or 50Hz with a low corner of 30Hz.
The other thing which you will find is that for a fixed low corner and driver, increasing the length of the portion past the front driver Tap moves the “wiggles” higher in frequency AND makes the driver appear to be a heavier, stronger driver.
In some cases, the best arrangement with a given driver may well be with the driver well inside while in another situation, the best spot for a given driver may be near the mouth like a TH-115 or Matterhorn (front Tap set back 5 feet from the mouth).
The whole point of the Tap is to provide additional acoustic loading in the region where a normal “too small” bass horn has low corner consisting of two peaks and a deep dip.
In the region where one had a deep saddle, one now has both sides of the radiation adding in phase. At the low corner (quarter wave resonance), only the “end” position feels any significant loading so it is sort of like having T&S parameters (SD?) which change with F, so far as the horn is concerned.
Best,
Tom
Well in this case, it is essentially a stock driver, having to design something around stock parts and all for a low volume product. I don’t expect there will be lots of Matterhorns built. It is a particularly rugged driver with parameters I could deal with for something as big as the Matterhorn thing, worked well in the TH-50 too.
If you guys are playing with Tapped horns, some one should pop for a program which will model them, like AKABAK.
I can maybe give you guys another clue or two which will help understanding how it works. As one approaches the low corner on a conventional bass horn, the horn acts more and more like a slug of air, it has mass which appears to increase as the frequency falls. In a normal horn, that reactance is adjusted by changing the “t” and ideally exactly off set by the compliance of the driver in a sealed box. With the Tapped horn, one has no rear volume so to get the lowest low corner, one needs the driver’s Fs to be somewhat above the low cutoff. For example, it wouldn’t be unusual to have an Fs of 45 or 50Hz with a low corner of 30Hz.
The other thing which you will find is that for a fixed low corner and driver, increasing the length of the portion past the front driver Tap moves the “wiggles” higher in frequency AND makes the driver appear to be a heavier, stronger driver.
In some cases, the best arrangement with a given driver may well be with the driver well inside while in another situation, the best spot for a given driver may be near the mouth like a TH-115 or Matterhorn (front Tap set back 5 feet from the mouth).
The whole point of the Tap is to provide additional acoustic loading in the region where a normal “too small” bass horn has low corner consisting of two peaks and a deep dip.
In the region where one had a deep saddle, one now has both sides of the radiation adding in phase. At the low corner (quarter wave resonance), only the “end” position feels any significant loading so it is sort of like having T&S parameters (SD?) which change with F, so far as the horn is concerned.
Best,
Tom
some questions Tom...
can you elaborate on your comment on the "front driver tap"? This sounds like you are suggesting that there are tap positions on both sides of the driver that can be manipulated. In other words one could extend the mouth past the driver position to impact loading (closer or farther away) with a given throat position as well as moving the position of the throat of the horn relative to the driver again closer or farther away. If the horn So was made to equal driver Sd could one then manipulate the length of horn between the driver and the throat? Is this in line with what you were referring to? As to AKABAK well I can't fly paint so that will be left to the guys that can dance with such programs. Thanks for posting and helping to bring the TAP horn into the DIY world.
can you elaborate on your comment on the "front driver tap"? This sounds like you are suggesting that there are tap positions on both sides of the driver that can be manipulated. In other words one could extend the mouth past the driver position to impact loading (closer or farther away) with a given throat position as well as moving the position of the throat of the horn relative to the driver again closer or farther away. If the horn So was made to equal driver Sd could one then manipulate the length of horn between the driver and the throat? Is this in line with what you were referring to? As to AKABAK well I can't fly paint so that will be left to the guys that can dance with such programs. Thanks for posting and helping to bring the TAP horn into the DIY world.
GM said:
I'm not sure what you bass that statement on, I have done extensive modeling on many drivers.
I have found 12" drivers that are marginally more capable the Lab 12 bellow ~35Hz, and the only drivers that are possibly better sub 35Hz subwoofers cost twice as much or more.
I haven't totally digested what Tom has said about the Tapped Horn Drivers FS Higer than the Horns Low Cut. But perhaps the rules are different in a TH.
I have 4 lab 12's in a 12cu' vented cab tunned to 21Hz. It does about as good as a conventional reflex cab of that size can in that frequency range. I have not found any compelling reason to switch to some of the drivers that cost 2-4 times more and only give a dB or 2 more output.
Maybe I'm missing something but it seems that most woofers with a really high BL have a huge midbass output, but as you drop into the sub bass regions that extra motor strength doesn't actually help the driver displace any more air than a driver with a much weaker motor.
The statement that the driver doesn't have enough mass doesn't make sense to me either. It has enough mass that its Fs is around 21Hz. The More mass you add to the driver the Weaker the BL, or motor strength. So your caught chasing your tail. Think about it.
I don't think correctumundo is an accurate response to the posters assertion.
I still belive the Lab12 is one of the best subwoofers you can buy for the price weather or not its the best choice for a TH I can't say, but from what I understand the Driver in the DTS-20 is a slightly modified Lab 12 driver. But only Tom and a DSL representitive can verify that.
S-Master
I,too, am curious as to what that statement was based on.I have been using 2 LABhorns for some time, and the results so far with the tapped horns I built would indicate that the LAB12 driver is an excellent choice for a tapped horn.
I have been so busy (work) that I haven't even had time to listen to the folded tapped horn I built Mon,and have to go back to work in a few hours.:-(
I will have the next few days off,so I should be able to get some measurements and the plans for the folded horn drawn up and posted.
I have been so busy (work) that I haven't even had time to listen to the folded tapped horn I built Mon,and have to go back to work in a few hours.:-(
I will have the next few days off,so I should be able to get some measurements and the plans for the folded horn drawn up and posted.
Don Bunce said:
Don,
Am I correct in assuming that this folded TH you talk about is multi-fold, unlike the single fold monoliths you posted about earlier?
Are they good for music too?
What's the bass like subjectively (I know you said it doesn't have the punch of the labs but I'm hoping that doesn't mean "one note" or "compressed")?
Thanks
Sorry to keep you guys in suspense,but I had to work Sun,a double shift on Mon,just haven't had time...
The folded tapped horn is 45"x28"x18".I cut the 14" wide horn I made the other day in half,cut notches in the sides and glued and screwed them together side by side.
I have been comparing the folded horn to the straight 15.5"wide horn,so far the winner by far is the folded version.goes deeper,tighter,less resonant. Excellent for music,this is no one notey boom box.
I never really got a chance to compare the 14"straight horn to the 15.5" horn,plus they are in opposite corners of the room.Tomorrow I will switch them around to see what difference room placement has on them,and take some measurements.
If the folded horn still wins,I will cut the 15.5" horn down to 14" to compare against the folded horn.
Here's a photo of the folded version.
http://img47.imageshack.us/img47/8573/foldedtappedhorn0050sq9.jpg
The folded tapped horn is 45"x28"x18".I cut the 14" wide horn I made the other day in half,cut notches in the sides and glued and screwed them together side by side.
I have been comparing the folded horn to the straight 15.5"wide horn,so far the winner by far is the folded version.goes deeper,tighter,less resonant. Excellent for music,this is no one notey boom box.
I never really got a chance to compare the 14"straight horn to the 15.5" horn,plus they are in opposite corners of the room.Tomorrow I will switch them around to see what difference room placement has on them,and take some measurements.
If the folded horn still wins,I will cut the 15.5" horn down to 14" to compare against the folded horn.
Here's a photo of the folded version.
http://img47.imageshack.us/img47/8573/foldedtappedhorn0050sq9.jpg
AkAbak
I just downloaded AkAbak.
Thanks for mentioning this program. It seems one can have serious fun modelling all kinds of loudspeakers, its like an acoustical playground. And its very complex. I am still reading the manual ;D
If someone besides me has looked into it, do you have a idea how to simulate a TH in it? Perhaps one could connect two horn structures to the same driver, one for the 1/2 wave and one for the 1/4 wave, since the sound travels both ways in the horn? Will the interaction of both be present in this simulation?
I just downloaded AkAbak.
Thanks for mentioning this program. It seems one can have serious fun modelling all kinds of loudspeakers, its like an acoustical playground. And its very complex. I am still reading the manual ;D
If someone besides me has looked into it, do you have a idea how to simulate a TH in it? Perhaps one could connect two horn structures to the same driver, one for the 1/2 wave and one for the 1/4 wave, since the sound travels both ways in the horn? Will the interaction of both be present in this simulation?
Hello Freddi,Mavo,Tom and others,
Like Tom mentioned Akabak is a real wonderfull program (it is even much more).
I used it al the times for some modeling work; horns vented or direct radiator systems. These are just some type`s that could be modeled with the standard build in lumped elements. It`s even possible to investigate the acoustic elements itselfs. For someone who wants to go a little deeper, with a relative simpel program, this is definitely the way to go.
But if you want to model something like a Karlson or a Tapped horn this could not simply be done with the standard build in lumped elements, because the value of a element is varying in relation with the wavelenghts/pathlenght.
Regarding to the subject of the tapped horn it`s possible to shortcut (grounding) the back of the radiatorarea. When this is done, the system should be representable for everytime it hits a deep notch due to the reflection, occuring every 2F.
When the front and back are in phase maybe the pressure in the horn at the Tap should be converted to a acoustic compliance. The value (not it`s impedance) of this compliance is freq. dependent. The way how it`s couple to the back of the radiator should be a function on his own (something like a parabool, see link)
http://users.pandora.be/chris.cambre/chris.cambre/tweedegraadsfuncties.htm
Something like these functions could easily be integrated in Akabak.
Does someboady know what part in the horn let a driver seems to be a heavier/stronger motor than required for that horn when the driver is shifted away from his throat? Like you see at William Cowan`s side.
Cheers,
Marcel
Like Tom mentioned Akabak is a real wonderfull program (it is even much more).
I used it al the times for some modeling work; horns vented or direct radiator systems. These are just some type`s that could be modeled with the standard build in lumped elements. It`s even possible to investigate the acoustic elements itselfs. For someone who wants to go a little deeper, with a relative simpel program, this is definitely the way to go.
But if you want to model something like a Karlson or a Tapped horn this could not simply be done with the standard build in lumped elements, because the value of a element is varying in relation with the wavelenghts/pathlenght.
Regarding to the subject of the tapped horn it`s possible to shortcut (grounding) the back of the radiatorarea. When this is done, the system should be representable for everytime it hits a deep notch due to the reflection, occuring every 2F.
When the front and back are in phase maybe the pressure in the horn at the Tap should be converted to a acoustic compliance. The value (not it`s impedance) of this compliance is freq. dependent. The way how it`s couple to the back of the radiator should be a function on his own (something like a parabool, see link)
http://users.pandora.be/chris.cambre/chris.cambre/tweedegraadsfuncties.htm
Something like these functions could easily be integrated in Akabak.
Does someboady know what part in the horn let a driver seems to be a heavier/stronger motor than required for that horn when the driver is shifted away from his throat? Like you see at William Cowan`s side.
Cheers,
Marcel
G'day Marcel
I was involved in a project that developed a Mathcad model for the tapped horn. The easiest approach to modelling one of these horns is actually to model them as four horns loading one driver. There are four paths of interest in a tapped horn, the direct paths from the front and rear of the driver to the mouth and the two reflected paths from the thoat end of the horn. This model allows changes in geometry including the position of the driver along the path to be done very easily. You don't need to model a driver with varying Sd, the complex sum of the four paths will take care of that.
Cheers
William Cowan
I was involved in a project that developed a Mathcad model for the tapped horn. The easiest approach to modelling one of these horns is actually to model them as four horns loading one driver. There are four paths of interest in a tapped horn, the direct paths from the front and rear of the driver to the mouth and the two reflected paths from the thoat end of the horn. This model allows changes in geometry including the position of the driver along the path to be done very easily. You don't need to model a driver with varying Sd, the complex sum of the four paths will take care of that.
Cheers
William Cowan
Hi Marcel - Karlson are not taken seriously although it seems (??) dynamic output is good for low cone deflection at high spl. I think they can be fun for a 1951 "nonsense/joke" device. Sidebands seem reduced and I get loud levels at 1/16" p-p excursion.
k18 - cone does not move much for good output
http://img483.imageshack.us/img483/2388/nowayce7.jpg
Hi William - that model will offer great mobility and perhaps help with TH and tall transflex Karslson - if latter make sense.
Best,
Freddy
ps - forgot to add - Tom is awfully good in providing new elegant solutions - great to see TH
k18 - cone does not move much for good output
http://img483.imageshack.us/img483/2388/nowayce7.jpg
Hi William - that model will offer great mobility and perhaps help with TH and tall transflex Karslson - if latter make sense.
Best,
Freddy
ps - forgot to add - Tom is awfully good in providing new elegant solutions - great to see TH
K couplers
For some reason I think you would get more problematic reflected high frequency energy behind the exponential slot in the K coupler, than any improved driver loading in those ranges. I'm sure one would have lots of cancelations in the upper ranges.
I think the guy who is thinking of incorporating a K coupler into a Tapped horn design is missing the point of what a K is coupler is supposed to acomplish (Not that I really understand, but I think its a bunch of esoteric sillyness). A subwoofer doesn't need extra HF loading, and its not going to do anything for LF extension.
To me a Karlson coupler is like slicing an exponential horn down the center and taking that sliced plane and sticking it in front of a speaker. Perhaps arbitrarilly?
I think the best way evaluate the K-couplers performance would be to do some TEF, SMAART or Praxis (etc.) measurements of Frequency, Phase, Impedance, MLS, Impulse and Polar response. Then take the Exponential slot off, and do all the same meaurements. That should tell you a lot about what it really does.
As for modeling the thing I think that would be difficult, it would have to be able to do 3 dimensional vector predictions, and theres probably a lot of complex interaction going on between that driver and the cavity behind the coupler slot mostly in the upper ranges.
S~
For some reason I think you would get more problematic reflected high frequency energy behind the exponential slot in the K coupler, than any improved driver loading in those ranges. I'm sure one would have lots of cancelations in the upper ranges.
I think the guy who is thinking of incorporating a K coupler into a Tapped horn design is missing the point of what a K is coupler is supposed to acomplish (Not that I really understand, but I think its a bunch of esoteric sillyness). A subwoofer doesn't need extra HF loading, and its not going to do anything for LF extension.
To me a Karlson coupler is like slicing an exponential horn down the center and taking that sliced plane and sticking it in front of a speaker. Perhaps arbitrarilly?
I think the best way evaluate the K-couplers performance would be to do some TEF, SMAART or Praxis (etc.) measurements of Frequency, Phase, Impedance, MLS, Impulse and Polar response. Then take the Exponential slot off, and do all the same meaurements. That should tell you a lot about what it really does.
As for modeling the thing I think that would be difficult, it would have to be able to do 3 dimensional vector predictions, and theres probably a lot of complex interaction going on between that driver and the cavity behind the coupler slot mostly in the upper ranges.
S~