Hi all,
i dont know if this topic has already been discussed in this forum🙄 . i was thinking
.... if the port of a bandpass (or any ported) box be such that the length is decided by the helmontz resonator eqn, and the area expoentially increases from throat to mouth (just like horns)(something like the "wicked one" in Decaware😀 ), will the efficiency increase? Will this really work😕 ? I read somewhere that the area in the helmontz equation is the minimum area of the port. Any thoughts on this?
Venki😀
Ps:Sorry for my grammar😉
i dont know if this topic has already been discussed in this forum🙄 . i was thinking
.... if the port of a bandpass (or any ported) box be such that the length is decided by the helmontz resonator eqn, and the area expoentially increases from throat to mouth (just like horns)(something like the "wicked one" in Decaware😀 ), will the efficiency increase? Will this really work😕 ? I read somewhere that the area in the helmontz equation is the minimum area of the port. Any thoughts on this?Venki😀
Ps:Sorry for my grammar😉
Hi Venki,
simple answer is no it won't work.
The "horn" is far too short to work at bass frequencies.
🙂 /sreten.
simple answer is no it won't work.
The "horn" is far too short to work at bass frequencies.
🙂 /sreten.
It's a fairly common concept. Of course it doesn't need to be exponential, other hornflares are possoble as well.
The Band Pass Horn ussually is a hybride of a 4th order BP and a hornshaped port. In concept any order BP is possible. But most BPH are 4th order, basically just horns that are to short to fully function as an horn. For example the HD15 from speakerplans:
http://www.speakerplans.com/index.php?id=hd15horn
An other concept is the hybride of a basreflex and a horn:
http://www.iven.nl/fotoarchief/fotoarchief3_bestanden/dap sm18b.jpg
A basreflex is based on a mass-spring principle, where the Helmholzresonator is the mass and the air inside the box works as an spring. So the area is just a part of the equation to form the mass and therefore in this case you can not aspect the smallest area to be the actual area of the port since the difference is quite large.
Eiter by looking at the basreflex or BP aspects you can predict the response, because they can act as both do. For instance lowering f3 by stacking multiples. The concept does however focus on 50 -60 Hz and up most of times to be effective.
Wkr Johan
The Band Pass Horn ussually is a hybride of a 4th order BP and a hornshaped port. In concept any order BP is possible. But most BPH are 4th order, basically just horns that are to short to fully function as an horn. For example the HD15 from speakerplans:
http://www.speakerplans.com/index.php?id=hd15horn
An other concept is the hybride of a basreflex and a horn:
http://www.iven.nl/fotoarchief/fotoarchief3_bestanden/dap sm18b.jpg
A basreflex is based on a mass-spring principle, where the Helmholzresonator is the mass and the air inside the box works as an spring. So the area is just a part of the equation to form the mass and therefore in this case you can not aspect the smallest area to be the actual area of the port since the difference is quite large.
Eiter by looking at the basreflex or BP aspects you can predict the response, because they can act as both do. For instance lowering f3 by stacking multiples. The concept does however focus on 50 -60 Hz and up most of times to be effective.
Wkr Johan
sreten and Rademakers Thanx for the Quick replys..
Hey Rademakers, you mean this should work😀 ..neways are there any advantages of using the configuration over the conventional bass reflex boxes😕 ? Are there any rules (eqns for eg) for designing such boxes?
Thanks in Advance,
Venki.😀
Hey Rademakers, you mean this should work😀 ..neways are there any advantages of using the configuration over the conventional bass reflex boxes😕 ? Are there any rules (eqns for eg) for designing such boxes?
Thanks in Advance,
Venki.😀
So, Rade, could you describe a little more in depth how the Wicked one by decware should/does work?
Wherever I ahev asked this question I have usually gottent the whole "the horn isn't long enough to produce bass" yet I have builat several and all blow my mind.
Wherever I ahev asked this question I have usually gottent the whole "the horn isn't long enough to produce bass" yet I have builat several and all blow my mind.
Depends on the design parameters. The horn length needs to be close to 1/4 wavelength of the frequency it's going to support. The low cut off can be pushed down by using a larger rear chamber and/or front chamber at the cost of powerhandling. By putting it in 1/4 th or 1/8 th space the f3 is lowered.
Benefit would be the high efficiency compared to basreflex. Downside is that it doesn't go really low, 4th order BPH make excellent kickbins.
There are some 4th order BPH mainly used in PA that can go pretty low, they're also pretty big as well. The low end extension in those cases mostly depends on the principle of the 4th order BP which has increased efficiency in trade of bandwidth.
"The Wicked One" would behave in a similar way. The length of the horn is long enough to support hornloading down to an estimated 70 Hz (upper bass frequencies). The horn mouth however is way to small to support full hornloaded efficiency down to 70 Hz (each driver takes half).
Anything under that frequency is mostly going on the 4th order BP principle.
@Relax: "It's not a horn". So what, you're still impressed 🙂
The sound of a 4th order BP can be very impressive. Same goes for TL, basreflex, 6th order BP, etc etc..
It doesn't have to be hornloaded to be impressive.
@Venki:
4th order BPH's can be simulated with Hornresp (see diy Wiki), same goes for the basreflex-horn-hybrid (that last one should be seen as an short back loaded horn (aka rear loaded).
Wkr Johan
Benefit would be the high efficiency compared to basreflex. Downside is that it doesn't go really low, 4th order BPH make excellent kickbins.
There are some 4th order BPH mainly used in PA that can go pretty low, they're also pretty big as well. The low end extension in those cases mostly depends on the principle of the 4th order BP which has increased efficiency in trade of bandwidth.
"The Wicked One" would behave in a similar way. The length of the horn is long enough to support hornloading down to an estimated 70 Hz (upper bass frequencies). The horn mouth however is way to small to support full hornloaded efficiency down to 70 Hz (each driver takes half).
Anything under that frequency is mostly going on the 4th order BP principle.
@Relax: "It's not a horn". So what, you're still impressed 🙂
The sound of a 4th order BP can be very impressive. Same goes for TL, basreflex, 6th order BP, etc etc..
It doesn't have to be hornloaded to be impressive.
@Venki:
4th order BPH's can be simulated with Hornresp (see diy Wiki), same goes for the basreflex-horn-hybrid (that last one should be seen as an short back loaded horn (aka rear loaded).
Wkr Johan
Thanks for the info
Rademakers,
Hey by the way will i be able to simulate the 4th order BP box with exponential ports using the Hornresp program???
I read somewhere (in some website) that we can make a horn shorter for the same frequency by:-
finding the mouth area of the horn and dividing it by 5(rule of thumb i think) and reducing the length of the horn to flare till this area.
If this works (i have not tried),this should work more or less like the flared reflex box.
am I correct. Any thoughts on this?
The above method would compromise for the efficiency.
Venki.😀
Rademakers,
Hey by the way will i be able to simulate the 4th order BP box with exponential ports using the Hornresp program???
I read somewhere (in some website) that we can make a horn shorter for the same frequency by:-
finding the mouth area of the horn and dividing it by 5(rule of thumb i think) and reducing the length of the horn to flare till this area.
If this works (i have not tried),this should work more or less like the flared reflex box.
am I correct. Any thoughts on this?The above method would compromise for the efficiency.
Venki.😀
venki said:Thanks for the info
Rademakers,
Hey by the way will i be able to simulate the 4th order BP box with exponential ports using the Hornresp program???
I read somewhere (in some website) that we can make a horn shorter for the same frequency by:-
finding the mouth area of the horn and dividing it by 5(rule of thumb i think) and reducing the length of the horn to flare till this area.
If this works (i have not tried),this should work more or less like the flared reflex box.
The above method would compromise for the efficiency.
Venki.😀
Nope, hornresp wont simulate this.
"finding the mouth area of the horn and dividing it by 5(rule of thumb i think) and reducing the length of the horn to flare till this area."
This sound more like (if you can) get the mouth placed in a corner you can do this because the walls will extend the rest of the horn.
You would still have the effeciency though.
Hi Coolin,
I dont think the 1/5 rule is restricted to coner horns...but not sure...
let me try and find the link...
Thanx,
Venki.😀
I dont think the 1/5 rule is restricted to coner horns...but not sure...
let me try and find the link...
Thanx,
Venki.😀
Yes, you can, but:
Look at it as a (4th order) BPH rather then a 4th order BP with exponential ports. So it's now designed like a horn, meaning you're not going to choose chamber volumes and tune it to a specific frequency.
The design characteristics would be a large rearchamber, a large frontchamber and a short horn (instead of port). The horn doesn't need to be exponential tho. Other horn flares like conical, hyperbolic, catenoidal and about anything in between is possible. Exponential is a good start.
Wkr Johan
Venki,
I haven't read all of this site (http://www.haliaetus.com/va/haliaetus.html), but I'd think you'd be looking for a jet shape,rather than a horn shape. And I'm not sure if efficiency is increased. But you can play louder through the same sized port due to decreased turbulence.
I haven't read all of this site (http://www.haliaetus.com/va/haliaetus.html), but I'd think you'd be looking for a jet shape,rather than a horn shape. And I'm not sure if efficiency is increased. But you can play louder through the same sized port due to decreased turbulence.
Decware WO
So what woudl this enclosure theoretically do with a single JBL GTI.
http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W15GTi_rev_f.pdf
if I scaled it up to this:
The lines represent the shortest and longest lengths of the horn? or port in inches.
and the numbers in the boxes are the area in inches square of each chamber.
Heighth can be anywhere between 17-19 inches, if that helps get a big SPL.
Then the question comes on how to port the sealed sections. I want pure SPL so I was thinking it needs to be ported at the frequency when the front and back waves add totally. But I don't know how to figure that out...
Can anyone tell us how to model the exponetial port in winISD, or does it require hornresp or soemthing?
So what woudl this enclosure theoretically do with a single JBL GTI.
http://manuals.harman.com/JBL/CAR/Boxes and Parameters/W15GTi_rev_f.pdf
if I scaled it up to this:
The lines represent the shortest and longest lengths of the horn? or port in inches.
and the numbers in the boxes are the area in inches square of each chamber.
Heighth can be anywhere between 17-19 inches, if that helps get a big SPL.
Then the question comes on how to port the sealed sections. I want pure SPL so I was thinking it needs to be ported at the frequency when the front and back waves add totally. But I don't know how to figure that out...
Can anyone tell us how to model the exponetial port in winISD, or does it require hornresp or soemthing?
The people who told you that the horns are too short are right, what you end up with is closer to a bandpass enclosure than a horn, that doesn't stop it producing bass, but it does stop the acoustic gain that you would get from a properly sized horn.
If you want spl and have the space build a big bandpass enclosure, I took the liberty of modeling you an example; (see attachment)
I could use hornresp and model that design but I can gurantee it won't match this bandpass design for pure spl.
[edit] don't forget to add ~15db to that model to account for cabin gain
If you want spl and have the space build a big bandpass enclosure, I took the liberty of modeling you an example; (see attachment)
I could use hornresp and model that design but I can gurantee it won't match this bandpass design for pure spl.
[edit] don't forget to add ~15db to that model to account for cabin gain
Attachments
WHats killing me is that this enclosure does killer bass for my ten inchers. I have 2 infinity 10s that just pound, hitting over 126 db with 230w a piece. I just don't know how to scale it or even model it.
I am gonna try hornresp.
I am gonna try hornresp.
Got the link is it the "Big Fun Horn"
http://kosat.consultit.no/~ketil/lowther/bigfunht.html#HD_NM_6
{Edit]
another one
http://kosat.consultit.no/~ketil/lowther/ALLFUN/Size.html (look for compromise😉 )
Venki.😀
http://kosat.consultit.no/~ketil/lowther/bigfunht.html#HD_NM_6
{Edit]
another one
http://kosat.consultit.no/~ketil/lowther/ALLFUN/Size.html (look for compromise😉 )
Venki.😀
The link seems (to me) to provide you with the theory to calculate a free space (4 pi) horn. The section under compromise tells you how to calculate those numbers to a typical domestic environment (smaller than 2 pi).
The author also states not to care about a flat frequency response because the room interactions will cause interference anyway (this is true). For both ways (flat response or not) things can be said, I would see this as a personal choice rather than to be absolutely true or false.
The interface/layout of Hornresp is often thought to be slightly difficult (the DIY Wiki should overcome this). However it seems to be easier as the (hardcore) method used by the designer of the BIG FUNnel 😉
Wkr Johan
The author also states not to care about a flat frequency response because the room interactions will cause interference anyway (this is true). For both ways (flat response or not) things can be said, I would see this as a personal choice rather than to be absolutely true or false.
The interface/layout of Hornresp is often thought to be slightly difficult (the DIY Wiki should overcome this). However it seems to be easier as the (hardcore) method used by the designer of the BIG FUNnel 😉
Wkr Johan
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