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This thread got me thinking a bit about horns during lunch today. How do they achieve such large displacement and high sensitivity? Nothing is free, so we must be trading one thing to get something else. If I'm understanding the physics correctly, what we are essentially trying to do is take advantage of the force of the motor assembly and leverage it as much as possible. We are banking on the motor and cone being strong enough to move a much larger mass of air than just the cone would itself in free air. For a driver well suited to horn use, we are basically saying the motor assembly is capable of much more than just moving the attached cone, right? The mouth of the horn becomes a much larger radiating area than the cone, but they are coupled together. Any experts on horns can feel free to correct me here.

If that is correct, then could we not achieve a similar end by taking a motor assembly and using a much larger cone? Isn't that ultimately kind of what we are doing with horns? Kevin has made a 21" Maelstrom that uses the same motor assembly as the 18", but if he used a carbon fiber/honeycomb cone for maximum rigidity without getting too heavy, would he be able to get away with say a 36" diameter driver? If the weight didn't increase too much, wouldn't sensitivity go way up? Wouldn't max output capability go way up? Wouldn't harmonic distortion go way down?

Am I way off, spot on, or somewhere in between?
 

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This thread got me thinking a bit about horns during lunch today. How do they achieve such large displacement and high sensitivity? Nothing is free, so we must be trading one thing to get something else. If I'm understanding the physics correctly, what we are essentially trying to do is take advantage of the force of the motor assembly and leverage it as much as possible. We are banking on the motor and cone being strong enough to move a much larger mass of air than just the cone would itself in free air. For a driver well suited to horn use, we are basically saying the motor assembly is capable of much more than just moving the attached cone, right? The mouth of the horn becomes a much larger radiating area than the cone, but they are coupled together. Any experts on horns can feel free to correct me here.

If that is correct, then could we not achieve a similar end by taking a motor assembly and using a much larger cone? Isn't that ultimately kind of what we are doing with horns? Kevin has made a 21" Maelstrom that uses the same motor assembly as the 18", but if he used a carbon fiber/honeycomb cone for maximum rigidity without getting too heavy, would he be able to get away with say a 36" diameter driver? If the weight didn't increase too much, wouldn't sensitivity go way up? Wouldn't max output capability go way up? Wouldn't harmonic distortion go way down?

Am I way off, spot on, or somewhere in between?
all I can say is "ditto" or "I concur"
 

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Discussion Starter #85
Horns are an acoustical impedance transformer. They couple the driver to the air in a way that allows the driver to get a "grip on a much larger chunk than if it was just vibrating in the open as in a sealed box. Simply increasing cone size won't do the same thing. Steve your example would be a very efficient driver though.



http://www.scribd.com/doc/9778607/Loudspeaker-Horn-Theory-An-Introduction-Part-1
 

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I've heard the finished sub was supposed to have a 3rd option for mouth location...but I assume with the mouth dimensions vs the sub's depth, it can't be located at the end, only on 1 of the large faces?
If it helps, the mouth area can be wrapped around a corner, though of course you need to leave some of it intact to form an 'L' angle brace. This will lengthen the horn's acoustic path-length a minor amount, shifting both its low and high tuning frequencies a fraction of a Hz, so inaudible. Really, the mouth of a TH is so acoustically small for its BW that it could be spread out over both sides and end plates, though in such a scenario it couldn't be placed hard against a boundary.

GM

edit: I see Ivan responded too: http://www.avsforum.com/avs-vb/showpost.php?p=17555702&postcount=1282
 

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Simply increasing cone size won't do the same thing.
Hmm, a horn is a folded up flat baffle, so unfold it to find its effective radiating area and use this as the driver's Sd to make a comparison of both radiation efficiency and directivity.

GM
 

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Discussion Starter #91
Back on topic a bit...

I watched a few movies with the DTS-10 last night after I got it set-up and integrated as well as I could. It handled the bass from both HellboyII and Horton Hear's a Who quite well at -10db. It has a very clean and effortless sound to it and it does pack impressive extension and power. Tonight I'll be trying out music for a more critical listening evaluation.

BTW I'm purposely not "seeing what she'll do" yet. That appears like it'll be quite a bit. I want to just listen for a few days to focus on the character of it's sound without worrying about how loud it'll go which seems to be what everyone is focused on right now. I'll check out that aspect later.
 

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If it helps, the mouth area can be wrapped around a corner, though of course you need to leave some of it intact to form an 'L' angle brace. This will lengthen the horn's acoustic path-length a minor amount, shifting both its low and high tuning frequencies a fraction of a Hz, so inaudible. Really, the mouth of a TH is so acoustically small for its BW that it could be spread out over both sides and end plates, though in such a scenario it couldn't be placed hard against a boundary.

GM

edit: I see Ivan responded too: http://www.avsforum.com/avs-vb/showpost.php?p=17555702&postcount=1282
:huh: :hissyfit: :foottap: :flex: :sneeky: :help: :ponder: :dontknow: :crying: :whistling: :R:boxer: :wave: :coocoo: :eek: :rant: :devil: :rofl2: :sarcastic: :yikes: :spend: :rubeyes: :unbelievable: :gulp: :doh: :D:scratch: :bigsmile: :T:dumbcrazy: :rolleyesno: :clap: :sad: :sn: :blink: :hsd: :paddle: :innocent: :rofl: :heehee: :nono: :sweat: :neener:

now i don't know what to do. make 4 of these squeeze into a van and modify the mouth, knowing it will SLAUGHTER 4 MX's ported.... BUT, I can't take some one eleses design, some one elses snap together, and put it in my setups. I can't. I have to design it myself. I have to build it myself.

Thanks for your find there, I'll have to make my way back over there later...ugh

Back on topic a bit...

I watched a few movies with the DTS-10 last night after I got it set-up and integrated as well as I could. It handled the bass from both HellboyII and Horton Hear's a Who quite well at -10db. It has a very clean and effortless sound to it and it does pack impressive extension and power. Tonight I'll be trying out music for a more critical listening evaluation.

BTW I'm purposely not "seeing what she'll do" yet. That appears like it'll be quite a bit. I want to just listen for a few days to focus on the character of it's sound without worrying about how loud it'll go which seems to be what everyone is focused on right now. I'll check out that aspect later.

Awesome Josh, you know what youre doin. I like your plan of attack.
 

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Back on topic a bit...

I watched a few movies with the DTS-10 last night after I got it set-up and integrated as well as I could. It handled the bass from both HellboyII and Horton Hear's a Who quite well at -10db. It has a very clean and effortless sound to it and it does pack impressive extension and power. Tonight I'll be trying out music for a more critical listening evaluation.

BTW I'm purposely not "seeing what she'll do" yet. That appears like it'll be quite a bit. I want to just listen for a few days to focus on the character of it's sound without worrying about how loud it'll go which seems to be what everyone is focused on right now. I'll check out that aspect later.
How does the DTS-10 compare to the two RE XXX 18's that you have in your HT?
 

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Awesome build.

Ill follow this one closely, looking forward to more opinions on the end result :)
 

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Discussion Starter #98
It compares quite well actually, but I haven't been comparing them head to head so to speak. Both are capable of more output than is really needed under all, but the most extreme circumstances. The crazy part is that it's just 2 $200 12" drivers that do what it does in my 4150cu ft room. It's all very good cabinet design and engineering.

I've had no problems out of the DTS-10 with any music or movie soundtrack yet. It hasn't even sounded bad on sine waves when I ran some loud sweeps. I'm not using a HPF other than the roll off in my amp and receivers response. It's got a lot of power and sounds very clean especially on the lows. It kicks hard in the upper bass where it's really efficient and watching Batman DK on BR at -5 had some really punchy hit you in the chest moments like the 50cal scene. It handled the whole movie at that level fine. I may try a movie or 2 this weekend at 0 and see what happens. The CE4000 has yet to clip either. Should be about 2000w available. It has very clean, solid output down to at-least 12hz in my room for ht effects and up above 30hz it will flat out wail on music.

The response that I have is not very good right now due to my room acoustics. I could use a second one and probably some EQ to even things out a bit.

I might see if I can get the finances together to get another one if that says anything. I think it's an absolute steal at under $1400 for the kit, an EP2500, accessories, etc.
 

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Discussion Starter #100
I ran 2 sampled kick drums and a bass drop like effect through the DTS10 strapped to a bridged CE4000 providing probably 2000w, 2 sealed 18" xxx's powered by a PL9.0 providing probably 3000w to each drive and also a Velodyne CT150 (ported 15", 300w rated) to stand in as a decent strength commercial sub. I increased the level of the Klipsch CF4 mains to about as loud as I thought feasible and left it there for all of the subs. Then using the SW level control I increased the output of the subs until each was either showing signs of distress or amp clipping was indicated with each sample and recorded the output of the sub with my ecm8000 into Spectrum Lab. I also used a Galaxy CM140 set to C weighting, fast response, 80-130db range, set at the listening position to record the max SPL with each sub on each sample. I figured that this would give me a sense of how dynamic each sub system could be when called upon in short bursts. I ran the subs both with and without the mains and recorded the results.

First thing of note is that the set-ups aren't exactly the same, as the subs are in as close to the same but still slightly different positions and subject to the room acoustics, so just take this as a sort of rough estimate of the dynamic capabilities of each influenced by the room. An 80hz xover was used. Also I don't think that the SPL meter is capturing the peak levels of these short events accurately. It seems to be really low compared to what I experienced. Tom commented about this a couple of times before, about instantaneous clipping going unnoticed and the inability of measurements to pick up the event fully. Makes one wonder.

The second sample in each waterfall is with the level reduced 5db.



Here's the first kick drum electrical.



Velodyne CT150 plus mains max output kick 1 112.2db. Clean but not as thick sounding as the other subs. Compressed.




Dual XXX plus mains max output kick 1 113.8db. Clean, seemed louder than registered on the meter, good attack. Ran out of amp.



DTS10 plus mains max output kick 1 116.8db. Clean, loud, huge attack, seemed much louder than the meter registered.


Velodyne CT150 alone max output kick 1 100.7db. Much weaker without the mains, compressed and not as deep or clean sounding.


Dual XXX alone max output kick 1 110.5db. Very clean, loud, ran out of amp. Seemed louder than indicated.



DTS10 alone max output kick 1 113db. Clean, very loud. Seemed louder than indicated.



Kick drum #2 electrical.


Velodyne CT150 with mains kick #2 max output 108.9db. Fairly clean, not as deep, seems compressed.



Dual XXX with mains kick #2 max output 113.8db. Loud, clean, good attack, seemed louder than measured, ran out of amp.


DTS10 with mains kick #2 max output 117.4db. Very loud, seemed fairly clean still, massive attack.



Velodyne CT150 alone kick #2 max output 104.4db. Weaker without the mains, less extended sounding, compressed.



Dual XXX alone kick #2 max output 110db. Clean, ran out of amp, louder subjectively than the meter indicates.



DTS10 alone kick #2 max output 113.8db. Very loud, seems clean and much louder than indicated by the meter.



Bass drop electrical


Velodyne CT150 bass drop with mains max output 109.1db. Very compressed lows, overdriven sounding.



Dual XXX bass drop with mains max output 113.2db. Very clean, loud, big room shake, ran out of amp, seemed louder.



DTS10 bass drop with mains max output 115db. Very loud, seemed louder, nice room shake. Thought I detected a hint of an over driven quality to the bass.



Velodyne CT150 bass drop alone max output 100.8db. Again much weaker without the mains. Squashed low end, sounded over driven, limited. Not much room shake. Mains outgun this sub.



Dual XXX bass drop alone max output 110.2db. Clean sounding output. Big room shake. Amp limited. Seemed louder.



DTS10 bass drop alone max output 110.7db. Loud, seemed louder than measured, good room shake, I think that the drivers were beginning to reach their excursion limits on this test. Sounded like there was some doubling going on without any masking content from other speakers. Right below amp clipping. Turning it down a few notches removed this aspect. Output did not seem to be compressing however.




As you can see the DTS-10 has a massive amount of bass output particularily above 40hz. It is very efficient. Seems to be about 8 or 9db more efficient than this particular pair of sealed 18's, which are admittedly innefficient above 30hz. Allowing it to produce higher levels on regular old rock music than the pair of 18's with 4.5db more power available to them.
 
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