Horn question? - Home Theater Forum and Systems - HomeTheaterShack.com

Old 03-22-10, 01:34 AM Thread Starter
Elite Shackster

Dylan

Join Date: Apr 2009
Posts: 1,358
Horn question?

I've been looking for more bass for my music stuff. For music and/or movies, would a Shiva-X in a horn tuned to whatever ideal frequency be able to beat out a Mal-X in a 7.6 cu.ft box tuned to 14hz with 2,000w?
How big would a horn have to be for a Shiva if it was tuned around 26hz for music listening strictly?
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Old 03-23-10, 05:57 PM Thread Starter
Elite Shackster

Dylan

Join Date: Apr 2009
Posts: 1,358
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Old 03-24-10, 01:43 AM
Elite Shackster

Mike

Join Date: Apr 2007
Posts: 19,397
Re: Horn question?

I can't help you Dylan, I know nothing about modeling horns. Hopefully someone who does will join in.
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Old 03-24-10, 10:15 AM
stu

Join Date: Dec 2009
Location: Johannesburg, South Afric
Posts: 17
Re: Horn question?

Hi Dylan, I am new to this forum but have been building horns for years so I will try to help.
I am not sure if what I am about to say is what you want to hear. Firstly 14Hz is below the ability of the human ear, secondly you need a very big room to sustain a half wavelength at 14Hz regardless of the type of speaker and third, no musical instrument can produce it. A large pipe organ 32ft will go down to 16Hz, next is a full size piano at 27.5Hz.
To answer your question: The cut off frequency of a horn is not dependent on the make of the driver but on some quite complex maths. Important factors are throat impedance, coupling to the driver, horn length and rate of flare, and specially the mouth area. The theoretical mouth circumference must be at least the wavelength at the cut off frequency. For the 27.5 Hz of the piano that would be 40 ft. But fear not. Working in the corner of a closed room this can be reduced to ⅛ of that. And (you probably know ) horns are usually folded to fit the length into a practical room so will not follow the theory too closely and some approximations are in order.
The design process is complex but I have some practical corner designs that will accommodate a 12 or 15 inch driver. The choice of driver is also different from other cabinets, specially subs.
The real advantage of the horn is not in achieving the lowest base frequency but rather efficiency - much higher than any other type of cabinet, low distortion - much lower, and smooth response over the entire frequency range with no troughs, humps and no sharp cut off below resonance as with bass reflex (except a little colouration from folding the horn).
If you listen to a well built horn system you will see and hear the difference.
You mention 2000w (or thats what it looked like) This is enough to not only demolish your hearing but probably your house. I drive my horns quite adequately from a 20w/ch amp and cannot listen to more than about 4 watts in a fair size room. (I also have a 100 watt amp for better headroom and lower distortion but the point remains).
Stuart

Last edited by Stuart; 03-24-10 at 10:22 AM.
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Old 03-24-10, 11:05 AM
Senior Shackster
Jeremy

Join Date: Dec 2009
Posts: 332
Re: Horn question?

Quote:
sub_junkie wrote: View Post
How big would a horn have to be for a Shiva if it was tuned around 26hz for music listening strictly?
There's a Shiva X2 tapped horn build in progress in the Exodus forum you might be interested in.

Horns aren't the easiest thing to design... some woofers work well, some don't work at all. My suggestion would be to go download Hornresp and start playing with it. It has a very steep learning curve, but once you get the hang of it you'll probably find that it gets addictive. It's addictive to me anyway.

In general, the higher the corner frequency, the shorter the horn can be. It's far easier to design a decent 26Hz horn than it is to get one that goes into the teens. And it's completely impractical to get one that goes into single digits due to the size.

My current dual Tang Band 8x12" tapped horn project is some 650 liters in size with a corner frequency of 16Hz. That was the smallest I could get it. It will be 74" x 17" x 42." It will not outdo a Mal-X I think (especially below the corner), but it will get plenty loud enough.

For a 26Hz horn, the Shiva is probably not the right driver for the application. I haven't really modeled it, so I'll have to leave that for others to comment on.

Last edited by Oklahoma Wolf; 03-24-10 at 11:21 AM.
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Old 03-25-10, 01:34 AM Thread Starter
Elite Shackster

Dylan

Join Date: Apr 2009
Posts: 1,358
Re: Horn question?

Quote:
Stuart wrote: View Post
Hi Dylan, I am new to this forum but have been building horns for years so I will try to help.
I am not sure if what I am about to say is what you want to hear. Firstly 14Hz is below the ability of the human ear, secondly you need a very big room to sustain a half wavelength at 14Hz regardless of the type of speaker and third, no musical instrument can produce it. A large pipe organ 32ft will go down to 16Hz, next is a full size piano at 27.5Hz.
To answer your question: The cut off frequency of a horn is not dependent on the make of the driver but on some quite complex maths. Important factors are throat impedance, coupling to the driver, horn length and rate of flare, and specially the mouth area. The theoretical mouth circumference must be at least the wavelength at the cut off frequency. For the 27.5 Hz of the piano that would be 40 ft. But fear not. Working in the corner of a closed room this can be reduced to ⅛ of that. And (you probably know ) horns are usually folded to fit the length into a practical room so will not follow the theory too closely and some approximations are in order.
The design process is complex but I have some practical corner designs that will accommodate a 12 or 15 inch driver. The choice of driver is also different from other cabinets, specially subs.
The real advantage of the horn is not in achieving the lowest base frequency but rather efficiency - much higher than any other type of cabinet, low distortion - much lower, and smooth response over the entire frequency range with no troughs, humps and no sharp cut off below resonance as with bass reflex (except a little colouration from folding the horn).
If you listen to a well built horn system you will see and hear the difference.
You mention 2000w (or thats what it looked like) This is enough to not only demolish your hearing but probably your house. I drive my horns quite adequately from a 20w/ch amp and cannot listen to more than about 4 watts in a fair size room. (I also have a 100 watt amp for better headroom and lower distortion but the point remains).
Stuart
Thanks for the reply. I actually didn't know that a full sized piano goes down to 27.50hz, and I've been playing piano for 10 years now. Been playing college level stuff since I was 10 (now 16). First college level song was a Liszt Hungarian Rhapsody. I've played many Liszt songs, some including the Transcendental Etudes. Now those are tough to play.

Back to subwoofer stuff. I did state that I have 2,000w on hand if needed. That's what I'm powering my Mal-X with right now, and I'm just wanting more for my music listening. I have a spair 150w plate amp laying around somewhere, so I guess I could use it, but I would prefer to use the EP2500, and just take it easy with the power levels.

If I could build a horn tuned for something around 26hz, would the dimmensions be taller than say 48 or 50 inches? Basically, what I'm getting at is, what are the dimmensions that I could expect for a horn that is tuned at 26hz?

Thanks for the post. It built on my understanding of horns.

Last edited by sub_junkie; 03-25-10 at 01:48 AM.
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Old 03-25-10, 01:47 AM Thread Starter
Elite Shackster

Dylan

Join Date: Apr 2009
Posts: 1,358
Re: Horn question?

Quote:
Oklahoma Wolf wrote: View Post
There's a Shiva X2 tapped horn build in progress in the Exodus forum you might be interested in.

Horns aren't the easiest thing to design... some woofers work well, some don't work at all. My suggestion would be to go download Hornresp and start playing with it. It has a very steep learning curve, but once you get the hang of it you'll probably find that it gets addictive. It's addictive to me anyway.

In general, the higher the corner frequency, the shorter the horn can be. It's far easier to design a decent 26Hz horn than it is to get one that goes into the teens. And it's completely impractical to get one that goes into single digits due to the size.

My current dual Tang Band 8x12" tapped horn project is some 650 liters in size with a corner frequency of 16Hz. That was the smallest I could get it. It will be 74" x 17" x 42." It will not outdo a Mal-X I think (especially below the corner), but it will get plenty loud enough.

For a 26Hz horn, the Shiva is probably not the right driver for the application. I haven't really modeled it, so I'll have to leave that for others to comment on.
I'm following the Shiva horn build with great interest. That's what sparked my idea for using a horn for my music listening

I'm downloading Hornresp right now. I find that WinISD is also addicting. I'm constantly trying to find out new box sizes, tunings, and all other things...

What drivers would you guys recommend for a 26hz horn?
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Old 03-25-10, 06:12 AM
stu

Join Date: Dec 2009
Location: Johannesburg, South Afric
Posts: 17
Re: Horn question?

Thanks for the reply, and well done playing those etudes at 16. I am 66, don't play any instrument but love good music, specially classical and jazz (Brubeck, also a great pianist). My wife and I love piano, Liszt and Chopin. I listen to live symphony concerts as much as possible. We are blessed with plenty of world class talent here in SA, and JPO is very good and head-quartered quite close to my home. My radio stays tuned to our excellent ClassicFM .
Been dabbling in audio since about 16, in total ignorance at first, built my first horns in 1968 and became an addict. I began work as a trainee electronics techy after school. I built my own amp and pre-amp and improved horns. A musician friend (violin) was so impressed he asked me to build similar for him. Then another mutual friend (Mmus Wits, musicologist & Piano and choir master) asked me to do the same for him. He said that it was the most natural sound he had heard. This chap loved to play Chopin etudes for us and taught me about their significance in testing skills. I bought the then state of the art turn table - Transcriptor Fluid- hydraulically damped and ultra modern styling in 1970.
The horns were based on a Klipsch derivative published in Wireless World with a 15" driver for the base. The mid and tweeter have their own horns mounted on top. Fortunately my woodworking skills were up to it, but they are not easy to build.
I built a scaled down version with 12" drivers for those who have space / budget constraints . The sound is superb from both, and the lower cut off is about the same, depending on the room size. This clever corner design (bifurcated and folded symmetrically) utilises the walls of the room as the final stage, and so the mouth is determined by the diagonal of the room, and the listener is sitting in the mouth of the horn!
The size of the box (base horn for 15" driver) is: Height 40.5", W across front 24.2, across the narrow back 10.1, Depth diagonally out of the corner 24.4, with about 5" from the corner apex to the back plate, so altogether occupies a triangle about 30" diagonally from the corner and about 58" wide diagonally between adjacent walls. The sound emerges at the back along the walls and around the box. If this is difficult to visualise make a sketch. I will post one when I get to learn how to do that.
I will put together a summary of design principals with a sketch of the construction and post it when I have time.
Your comment on the lower range of the piano prompts me to offer a list of the main instruments with their frequency ranges. I should probably post it in a different thread as it is not about horns but relevant to all systems and listening rooms. Perhaps this info is already on the forum somewhere, but seems quite difficult to obtain these days. I am just beginning to explore the shack and enjoying it greatly.
Stuart is offline
Old 03-25-10, 10:22 AM Thread Starter
Elite Shackster

Dylan

Join Date: Apr 2009
Posts: 1,358
Re: Horn question?

Speaking of Chopin, I'm playing a Waltz and a prelude in G minor by him also.

Are there specific specs for a driver that makes it suited to horn duties? If I can know these specs, I could scout out some drivers and come back here and ask you all about them. Because I have absolutely no idea what drivers would be ideal to use in a horn.

In Hornresp when I input the parameters given in LittleMike's Shiva taped horn build, I see that the SPL graph is showing about 90dB at 20hz (If I remember correctly. I modeled it last night and am working from my memory lol). Would that be max SPL, or just something else?
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Old 03-25-10, 02:50 PM
Senior Shackster
Jeremy

Join Date: Dec 2009
Posts: 332
Re: Horn question?

There isn't any one spec that determines a good horn woofer, really. Just have to keep plugging them into Hornresp until you see one that looks good.

I haven't done a lot with traditional folded horns (or any kind other than tapped, really), but I will say that more often than not a good tapped horn woofer has a high-ish Fs and low Vas along with a stiff suspension. I've found a few car audio SPL type woofers that model pretty good. Working on a design right now for a dual HiFonics B10D4 horn that should do what my Tang Band horn plan does for extension only in less space with a bit more SPL and flatter response. If the TB horn doesn't please me, that may be the next thing I try. Or not. I can't stop playing with Hornresp.
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