Horn Length Questions

[bassmonster]

Reputation/marketing or opinion on people who supposedly know their stuff goes a long way it seems, explains why Dr Dre's Beats headphones still sell millions despite being made by Monster.

Dr. Dre sure knows how to make a beat, but Monster is a popular name brand that helps for marketing. I bet they were aiming for the young crowd on this one. I'm also betting that 95% of people buy them for their cool looks, because if sound quality were the main factor they would be spending that $600 on a quality set of Sennheiser instead of the style over substance thing. Unless of course, they bought Beats for the bass.

[Rich4349]

I've noticed that the throat to mouth ratio in the T39, T48, and T-60 all seem in the neighborhood of 20:1 or 5%. In the book

http://www.amazon.com/Hi-Fi-Loudspeaker ... 0810407213

he seems to operate off of a 2% or 50:1 ratio. Would it be correct to say that since those mouths are 250% bigger, their path lengths would have to be an equal % longer, therefore making a horn of a given extension and volume at that extension prohibitively large? So what element is sacrificed in order to use the smaller mouth and shorter path? Sound quality?

[Bill Fitzmaurice]

I've noticed that the throat to mouth ratio in the T39, T48, and T-60 all seem in the neighborhood of 20:1 or 5%. In the book

http://www.amazon.com/Hi-Fi-Loudspeaker ... 0810407213

he seems to operate off of a 2% or 50:1 ratio. Would it be correct to say that since those mouths are 250% bigger, their path lengths would have to be an equal % longer, therefore making a horn of a given extension and volume at that extension prohibitively large? So what element is sacrificed in order to use the smaller mouth and shorter path? Sound quality?

Horn length determines the low frequency limit, mouth area determines the sensitivity at that limit, it's as simple as that. A short horn with a large mouth will have high sensitivity but won't go low, and vis-versa.

[SeisTres]

download hornresp, and start playing with values on the "easy" input screen. As you move the sliders, you see the graph change in real time. Really simple to see how everything affects response. You can change just about anything from driver parameters to the shape/size of the horn.

[Rich4349]

Wow, Hornresp is some program. It would actually be usable, too, if it gave any indication as to what variable controlled what aspect. Because I was BORN knowing what "S1" is.

[Bill Fitzmaurice]

Wow, Hornresp is some program. It would actually be usable, too, if it gave any indication as to what variable controlled what aspect. Because I was BORN knowing what "S1" is.

That's why it comes with instructions.

[Rich4349]

Well without directions I give it a 1. With directions I give it a 1.5. Even reading 'hornresp for beginners', half of the variables don't even exist on the control panel, such as FLA / T. And about half of the parameters aren't in the included help file.

I'm reminded of my older brother (in our childhood):

Me: "What's (random whatever)?"
Him: "Look it up."

[Bill Fitzmaurice]

Well without directions I give it a 1.

Try muddling your way through AkAbak and you'll change that one to a ten. HornResp isn't for newbies, it assumes that you already have a good understanding of horn and driver theory. AkAbak assumes you already have a post-graduate degree.

[SeisTres]

Well without directions I give it a 1. With directions I give it a 1.5. Even reading 'hornresp for beginners', half of the variables don't even exist on the control panel, such as FLA / T. And about half of the parameters aren't in the included help file.

I'm reminded of my older brother (in our childhood):

Me: "What's (random whatever)?"
Him: "Look it up."

Once you start playing around with it you realize you reallly don't need to play around with all those variables, just the main ones. Which are the main ones you ask? pretty much the same ones you need from the driver if building direct radiating enclosures (Pe, xmax, bl, mass of cone, etc.) which are always the ones listed even on cheap drivers.

For horns all you really need the the length, mouth, throat, internal space and then if rear chamber ported and how big it is.

All the other stuff is really not needed if you're just playing around with it.

But yes, is it a HUGE learning curve with no real manual, just the help guide. If like me, you like theory more than the actual building, it's "fun" to learn.

[Jakob]

Hi to all, I have questions regarding a mid-bass horn for the B&C 12PE32 driver. A spherical wave horn with a S1 of 169 cm2 gets large ( 223 Liters), has a high SPL of 105 db and a usable frequency from 90 to 1200 Hz. Questions : will the 12PE32 be able to supply enough power to drive such a Glassfiber horn ? How should the throat chamber be configured to allow a maximum energy from the driver basket to the throat ? I don't know if a straight or exponential funnel would be better, or just a baffle with a central hole. And I am surprised that changing Vtc/Atc from 0 to high values does not modify the frequency response at all. Theory states that the size of Vtc acts as a low-pass filter. Am I wrong ? Thanks, Jake. PS could not upload the text file from HR - my fault ? sorry.
ID=28.00
Ang=2.0 x Pi
Eg=2.83
Rg=4.00
Fta=88.82
S1=169.00
S2=14649.08
Sph=94.49
F12=105.00
S2=0.00
S3=0.00
L23=0.00
AT=8.08
S3=0.00
S4=0.00
L34=0.00
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=522.00
Bl=19.10
Cms=4.00E-04
Rms=4.00
Mmd=17.49
Le=1.20
Re=5.80
Nd=1
Vrc=15.00
Lrc=10.00
Fr=0.00
Tal=0.00
Vtc=0.00
Atc=0.00
Pmax=100
Xmax=5.0
Comment=12PE230

[Tom Smit]

Jakob, first off, welcome to the forum. There is a lot of good, quick info here that is ready to help.
Second-this forum is generally for guidance on building Bill's cabs, and on sound theory.
Going on that, you may find the answer that you are looking for one another forum. The cabs here, are either subwoofers, full-range or top cabinets, although some have tried to shoe-horn a top cab into another location such as a midbasss. The general crossover frequency between the cabs is between 90 and 100hz...some use a little higher, some use a little lower cross freq .
I know that doesn't help you much with your question. Sorry.

[Jakob]

Thank You Tom, You Thread is called Horn Lenght Questions, nothing more or less. I saw no restrictions on what to ask. And Marc Coward is a crack for horns in general. Maybe someone has a useful answer. Have a nice day.

[SirNickity]

Sure, it's a general question... But this a support forum, not exactly the same motivation as, e.g., diyaudio. Threads that venture off into general theory serve to educate the users of Bill's products, so that they may better use them.

In short, you're not likely to get much assistance with a new design from this audience. No offense intended, of course..