I have been considering my ultimate sub and had narrowed it down to either IB or built in horn. The back wall of my listening room abuts the two car attached garage and has about 15 square feet of wall space that I can use for the system mouth. It boils down to spending a lot on drivers and power and very little on construction (IB) or a little on power and drivers and comparatively more on construction (horn).
Right now I am leaning toward a horn. A first pass on design is a 15" driver with straight mock hypex horn of about 10 square feet mouth opening. The actual implementation would be to approximate the taper using several conical sections. When playing with a 12" design it appeared that this approximation has very little negative consequence.
The horn response simulation done with a Dayton 15" Quatro sub is shown below. 1 Watt input gives about 105 dB but the plots shown are for 20W input. At this level we are still far from exceeding the 10mm Xmax of the driver. I would need to put in over 100 Watts (for 125+ dB at 16Hz to exceed Xmax.
I also did a simulation with an Eminence Beta 15 and it worked very well too (maybe even a little smoother and certainly much more efficient) but it has only about 4mm Xmax. It might however be an easier load for a tube amp.
Eventually I would like to drive it with a dedicated 6CA7 PP tube amp with a wee bit of negative feedback so the Pro driver might be a better bet in the long run.
Thoughts?
Right now I am leaning toward a horn. A first pass on design is a 15" driver with straight mock hypex horn of about 10 square feet mouth opening. The actual implementation would be to approximate the taper using several conical sections. When playing with a 12" design it appeared that this approximation has very little negative consequence.
The horn response simulation done with a Dayton 15" Quatro sub is shown below. 1 Watt input gives about 105 dB but the plots shown are for 20W input. At this level we are still far from exceeding the 10mm Xmax of the driver. I would need to put in over 100 Watts (for 125+ dB at 16Hz to exceed Xmax.
I also did a simulation with an Eminence Beta 15 and it worked very well too (maybe even a little smoother and certainly much more efficient) but it has only about 4mm Xmax. It might however be an easier load for a tube amp.
Eventually I would like to drive it with a dedicated 6CA7 PP tube amp with a wee bit of negative feedback so the Pro driver might be a better bet in the long run.
Thoughts?
Attachments
more info, please
A ten square foot mouth is too small. Even with corner loading, the response will be ragged. You didn't say how long the horn will be. Then there's the time delay to deal with. It is noticable.
I built a fifteen foot horn with a 10.8 square foot mouth, corner loaded. The bass fell off at 40hz. It ran at 105db 1w1m, but gave me problems with resonance peaks.
If you want to run a sub-bass horn, plan on much larger dimensions! If possible, keep it straight to eleminate resonance peaks.
The I.B. is a sweet proposition if you can afford the drivers. This is my next adventure. I'll use 8 Dayton Titanic Mkll drivers and load them into the garage below my media room.
No matter what you do, have fun😀
John Inlow
A ten square foot mouth is too small. Even with corner loading, the response will be ragged. You didn't say how long the horn will be. Then there's the time delay to deal with. It is noticable.
I built a fifteen foot horn with a 10.8 square foot mouth, corner loaded. The bass fell off at 40hz. It ran at 105db 1w1m, but gave me problems with resonance peaks.
If you want to run a sub-bass horn, plan on much larger dimensions! If possible, keep it straight to eleminate resonance peaks.
The I.B. is a sweet proposition if you can afford the drivers. This is my next adventure. I'll use 8 Dayton Titanic Mkll drivers and load them into the garage below my media room.
No matter what you do, have fun😀
John Inlow
Length is shown on the attatchment as 1227.79cm.
About 40.3 foot😱
wow thats a big horn😎 I think my labhorns are about 9 foot long.
The mouth is nearer 8 square foot btw.
Rob.
About 40.3 foot😱
wow thats a big horn😎 I think my labhorns are about 9 foot long.
The mouth is nearer 8 square foot btw.
Rob.
Good luck...
The mouth--where it enters at the corner of the room--should be considerably larger than what you've designed--36 sq.ft. seems like a minimum figure. 100 sq. ft. would be my choice. Otherwise, what you have is a horn with a section removed from the middle.
With a length exceeding forty feet, you'll most certainly want a time-delay unit in the signal path.
John
The mouth--where it enters at the corner of the room--should be considerably larger than what you've designed--36 sq.ft. seems like a minimum figure. 100 sq. ft. would be my choice. Otherwise, what you have is a horn with a section removed from the middle.
With a length exceeding forty feet, you'll most certainly want a time-delay unit in the signal path.
John
Great input guys. Yes at 40' length I would need one fold. I hadn't thought much about the delay. That could be a major factor. This "design" was just the raw output of the Hypex Designer of "Horn Response" with no adjustments at all. I was kind of surprised that it suggested such a small mouth size as well.
Would using two drivers (thus increasing the mouth area) shorten the length needed?
mike
Would using two drivers (thus increasing the mouth area) shorten the length needed?
mike
P.S. Delay
BTW what would you think is the maximum length where delay will not be a problem?
mike
BTW what would you think is the maximum length where delay will not be a problem?
mike
Re: P.S. Delay
you should easily be able to correct for delay using some active circuitry (i think behringer, amongst others, made something up to the task)
mashaffer said:
you should easily be able to correct for delay using some active circuitry (i think behringer, amongst others, made something up to the task)
You can correct the delay electronically, but it kills the sparkle on the top end. Maybe you can find an expensive DSP. My QSC DSP-30 is noticable when I insert it into the audio chain. It sounds like mid-fi, not hi-fi.
Two drivers will make the throat larger, thus shorten the horn.
I haven't finished my first cup of coffee, but let's play with some numbers: To be practical, what you want is a horn that is at least 1/4 wave length of the lowest frequency you wish to reproduce. 1100 (speed of sound) divided by 20 (low frequency cutoff) = 55 feet between pulses at 20hz. 55 divided by 4 (1/4 of the 20hz wavelength) = 13.75 feet minimum length of horn. When I design a 20hz horn, I start at the throat and create multiples of expansion every 36" thereafter. In the case of a hyperbolic design, you must go for more length between expansions points, hence the unusual length of your design. But, more length = more distortion.
So, using the more practical exponential, 20hz expansion: let's say your throat is 100 sq.in. (10" x 10")--thirty-six inches down the road it becomes 200 square inches--seventy two inches from the throat, it becomes 400 square inches. At 108" it has grown to 800 sq.in. At 144" it's 1600 sq.in. Then comes 180" with 3200 sq.in. mouth. Now, 180" divided by 12 = 15 feet of horn length. The sq.root of 3200 = 56.5" per side of mouth. This is rather truncated, but may work. I'd grow the horn another section or two to be safe. I.e., 216" at 6400 sq.in. mouth = 18 foot length with an 80 inch x 80 inch mouth. That's almost 7 feet by 7 feet. Now we're getting somewhere. place this in the corner of your room and let the natural wall expansion take over. The final mouth perimeter should add up to the length of the wavelength at cutoff. In your case, 20hz = 55 foot perimeter, or 7.4 feet per side.
This is pragmatic, will fit in your garage, and will sound so much better than a folded horn. I've learned from experience that a folded horn does not sound like hi-fi. It sounds like a P.A. system. P.A. is designed to run hard and is impressive sounding in that capacity. At home, no way. Build this horn and blow your mind!
John😀
Two drivers will make the throat larger, thus shorten the horn.
I haven't finished my first cup of coffee, but let's play with some numbers: To be practical, what you want is a horn that is at least 1/4 wave length of the lowest frequency you wish to reproduce. 1100 (speed of sound) divided by 20 (low frequency cutoff) = 55 feet between pulses at 20hz. 55 divided by 4 (1/4 of the 20hz wavelength) = 13.75 feet minimum length of horn. When I design a 20hz horn, I start at the throat and create multiples of expansion every 36" thereafter. In the case of a hyperbolic design, you must go for more length between expansions points, hence the unusual length of your design. But, more length = more distortion.
So, using the more practical exponential, 20hz expansion: let's say your throat is 100 sq.in. (10" x 10")--thirty-six inches down the road it becomes 200 square inches--seventy two inches from the throat, it becomes 400 square inches. At 108" it has grown to 800 sq.in. At 144" it's 1600 sq.in. Then comes 180" with 3200 sq.in. mouth. Now, 180" divided by 12 = 15 feet of horn length. The sq.root of 3200 = 56.5" per side of mouth. This is rather truncated, but may work. I'd grow the horn another section or two to be safe. I.e., 216" at 6400 sq.in. mouth = 18 foot length with an 80 inch x 80 inch mouth. That's almost 7 feet by 7 feet. Now we're getting somewhere. place this in the corner of your room and let the natural wall expansion take over. The final mouth perimeter should add up to the length of the wavelength at cutoff. In your case, 20hz = 55 foot perimeter, or 7.4 feet per side.
This is pragmatic, will fit in your garage, and will sound so much better than a folded horn. I've learned from experience that a folded horn does not sound like hi-fi. It sounds like a P.A. system. P.A. is designed to run hard and is impressive sounding in that capacity. At home, no way. Build this horn and blow your mind!
John😀
The comments I've heard from others is that folded bass horns are very hifi, but I can't yet comment from my own experience on that.
It's a good idea to play with numbers, and use hypex as a starting point. I believe the compression ratio is too high. The throat area should be no less than half the SD. A higher compression ratio than 2 means the driver must be very strong, or it will not ever be pushed.
Keep in mind that it may be bigger than you think, and you need to look at the foldings and geometry to see if you can actually fit it in!
Will this be built in?
It's a good idea to fire it into a corner and run it floor to ceiling. You might make two of them with a single 12" driver in each, stack them on top of each other. Get hornresp to calculate with two drivers, then make each box with the length specified, but half the mouth area each.
I've played around with a lot of designs, and what I found to work well was two horns with a 12" sub driver each (lab12 or similar) with 2 x 0.5m footprint running floor to ceiling. You can get it to 20 Hz and hit 120db easily at 20 Hz with 12.5w and not a lot of excursion is required for a sub driver.
When it comes to bass horns, I'm a bit of a beginner, but hope this helps.
It's a good idea to play with numbers, and use hypex as a starting point. I believe the compression ratio is too high. The throat area should be no less than half the SD. A higher compression ratio than 2 means the driver must be very strong, or it will not ever be pushed.
Keep in mind that it may be bigger than you think, and you need to look at the foldings and geometry to see if you can actually fit it in!
Will this be built in?
It's a good idea to fire it into a corner and run it floor to ceiling. You might make two of them with a single 12" driver in each, stack them on top of each other. Get hornresp to calculate with two drivers, then make each box with the length specified, but half the mouth area each.
I've played around with a lot of designs, and what I found to work well was two horns with a 12" sub driver each (lab12 or similar) with 2 x 0.5m footprint running floor to ceiling. You can get it to 20 Hz and hit 120db easily at 20 Hz with 12.5w and not a lot of excursion is required for a sub driver.
When it comes to bass horns, I'm a bit of a beginner, but hope this helps.
When it comes to hi-fi, everyone's entitled to their opinion, Paul. I think the sound wave at very low frequencies sound like pressure against my ears. Anything that can make them is fine. But when you go up into the second octave, my ears notice the lack of bass detail in a folded horn. That's why I'll never build another folded horn. Mind you, my gooseneck bass horn is very large and certainly efficient. It doesn't sound nearly as good as my higher frequency straight horns. The warmth/character is stripped away.
From what I read, most everyone who builds an enclosure says it sounds hifi, I'm no exception. But as time wears on, I allow my pride and memories of the effort exerted to move aside and truly examine what I've created. Straight always sounds better.
If I remember correctly, you submitted drawings to this forum, so I realize that when it comes to folded horns you've got a horse in this race...
John
From what I read, most everyone who builds an enclosure says it sounds hifi, I'm no exception. But as time wears on, I allow my pride and memories of the effort exerted to move aside and truly examine what I've created. Straight always sounds better.
If I remember correctly, you submitted drawings to this forum, so I realize that when it comes to folded horns you've got a horse in this race...
John
John, my horse is a bit of a theoretical horse at this stage. My theory tells me that folds should not be a problem, although parallel walls are a compromise which I'd be more concerned about. I have had a future dream project in my mind for some time - a 15 Hz unfolded exponential architectural horn where the mouth opens into a dedicated HT - a detached theatre with room within a room construction.
I wonder if this comparison is an apples to oranges comparison - different drivers and designs? Perhaps there are other factors accounting for the perceived difference ...
I wonder if this comparison is an apples to oranges comparison - different drivers and designs? Perhaps there are other factors accounting for the perceived difference ...
15hz huh... wow. I'd love to hear a horn like that.
I'm from the old school, where bass horns are huge and straight. Anything else is a compromise. I hate to compromise. I've always longed to tear off the sheetrock and sheathing from one side of my media room and plant a bass horn with a 10 foot by 20 foot mouth. I've got at least forty feet of room for horn length before the hillside gets in the way... oh, it fun to dream.
But, it is just a dream. This is why I'll be employing an Infinite Baffle design. This is a good bass system, from what I've read, and can do almost everything a bass horn can. It's just not as efficient. Heck, I've got four thousand watts of power just setting around waiting for a cool project. This will be it. I also have a Behringer Ultracurve DSP 24/96 on order. I ought to be able to create a decent bottom end slope.
Good luck with your horn. Have you ever considered using a triangular flair? No parallel walls there...
John
I'm from the old school, where bass horns are huge and straight. Anything else is a compromise. I hate to compromise. I've always longed to tear off the sheetrock and sheathing from one side of my media room and plant a bass horn with a 10 foot by 20 foot mouth. I've got at least forty feet of room for horn length before the hillside gets in the way... oh, it fun to dream.
But, it is just a dream. This is why I'll be employing an Infinite Baffle design. This is a good bass system, from what I've read, and can do almost everything a bass horn can. It's just not as efficient. Heck, I've got four thousand watts of power just setting around waiting for a cool project. This will be it. I also have a Behringer Ultracurve DSP 24/96 on order. I ought to be able to create a decent bottom end slope.
Good luck with your horn. Have you ever considered using a triangular flair? No parallel walls there...
John
Heck! Why stop there, make it 10 Hz!
I suppose you could say IB is a (much) more expensive way to get a similar result. With one option you are using a lot of drivers and power to move a whole lot of air directly, with the other you are coupling a small SD to a whole lot of air at the mouth.
It is interesting that both have one significant difference to conventional subs - they both seek to equalise the pressure on either side of the cone. A sealed or vented box will have higher pressure inside the box, but with IB it will be the same, and with a horn the sealed chamber will be sized to equalise the pressure on the other side of the cone caused by the mass of air in the horn.
Well then, while we are dreaming I'll have a dedicated HT room with 5 way active horns for the mains and a dedicated music 2 channel room with OB mains ...
Now that's getting a bit tricky! The current design is already quite tricky, and requires a large 150kg box to be jacked up 1.3m in the air! I should probably try out a simple 40 Hz bass horn to see how I like it first! ......... anyone in melbourne have a bass horn to show off?
I wish we were neighbors. My right channel is fully horn loaded down to 35hz; my left use twin JBL 2240s in a 12 cubic foot, sealed enclosure for the lower octaves. The JBLs can almost match the horns performance with EQ. They can never match it's efficiency, or full SPL. They are pretty to listen to, sweet. The horn isn't sweet; it just hammers away, clobbering anything in its path. For the first octave, I have a pair of very large TLs 4 feet behind my listening area loaded with 4) 12" LAB-12s.
Last night I was watching War of the Worlds. My wife had gone to bed, she had also given my permission to play this movie. Right after the first martian machine made its enterance she was running down to the media room asking if we had just had an earthquake. She was trembling. Just prior to her arrival, and acting on pure survival instinct, I had immediately turned down the volume--perhaps this is why I wasn't in the line of fire...
I apologized, thanked her for the compliment, then turned down the bass amps another notch. Our house is 4500 sq.ft.; we sleep on the third floor. She said all the windows and doors were rattling, everything was shaking. Hummm, isn't it an interesting time to be alive.
The Infinite Baffle I want to build will have 8) 15" or 18" drivers. The enclosure volume will be the garage. It will probably eat the T/Ls for breakfast.
Triangular horn walls are tricky, but easier than fabricating round walls. You can begin at one corner of the room and expand the subhorn to the other corner. It fits where the floor meets the wall. This way, if you have a large enough room, you can have 25 foot horns with one 135 degree bend at the mouth. It wouldn't be a bend, but rather, a reflector.
John
btw, you have a beautiful web site. Very cool.
Dr. Bruce Edgar folds his bass horns, so that's good enough for me to believe that folded bass horns can be hi-fi. Also Carpenter, what's this talk about top end sparkle in a bass horn?
johninCR: reread my post--the sparkle is removed from the top-end by the insertion of the DSP unit. When used as a delay, the DSP unit impacts the high frequency drivers when placed in their signal path.
If you like Dr. Edgar's approach, then good for you. Have a ball. I don't like the sound of a folded horn--now matter how you slice it, it's a compromise to a straight horn. I have a very large, 35hz bass horn with a slow bending gooseneck. It's not nearly as pretty sounding as my other high frequency, straight horns. As an aside, large horns tend to have large panels; large panels like to vibrate. Removing vibration requires more stiffening and/or added mass. Pretty soon you have a beast that dominates your room. Even on casters, my bass horn is a bear to move. When I install hardwood flooring I'll be concerned about the casters denting the wood floor. It's always something, isn't it?
BTW, my posts are just my opinions. Gosh, if you like the punch and immediacy of a folded horn, and can tolerate the coloration, then a horn should be in your listening room.
John
If you like Dr. Edgar's approach, then good for you. Have a ball. I don't like the sound of a folded horn--now matter how you slice it, it's a compromise to a straight horn. I have a very large, 35hz bass horn with a slow bending gooseneck. It's not nearly as pretty sounding as my other high frequency, straight horns. As an aside, large horns tend to have large panels; large panels like to vibrate. Removing vibration requires more stiffening and/or added mass. Pretty soon you have a beast that dominates your room. Even on casters, my bass horn is a bear to move. When I install hardwood flooring I'll be concerned about the casters denting the wood floor. It's always something, isn't it?
BTW, my posts are just my opinions. Gosh, if you like the punch and immediacy of a folded horn, and can tolerate the coloration, then a horn should be in your listening room.
John
Hi Carpenter,
I'm having trouble seeing how you can compare 2 horns that are designed to operate in different frequency bands. Was the midbass eq'd to give the same response as the basshorn ?
Rob.
I'm having trouble seeing how you can compare 2 horns that are designed to operate in different frequency bands. Was the midbass eq'd to give the same response as the basshorn ?
Rob.
Have you ever listened to a fully horn loaded system. If you have, then you can understand what I'm saying with regards to the sonic qualities of a straight horn vs. a folded horn. I.e., straight, high frequency horns vs. larger folded bass horns. Another approach is this: listen to a folded horn next to a nice sealed or bass reflex enclosure. The warmth and detail from the latter is noticable.
If you listen to amplifiers designed by Nelson Pass, you begin to appreciate that immediacy and intimacy is much more profound than being clobbered by a horn. Subtilities are just as important as power.
When I first began constructing bass horns some 25 years ago, I noticed that driver manufacturers would make statements similar to the ones I'm making here. I thought they were plain stupid. Nothing could sound better than a horn, especiall a BASS horn. Right? Several years after becoming the owner of a horn loaded stereo system, I've come to understand that they were not stupid. I was. I suppose that the proper word is "ignorant".
Robwells: it's very easy to listen to horns from different frequencies in the sound spectrum and appreciate their similarities and dissimilarities. Folded bass horns can easily color the bass. At certain frequencies, they can make lots, and lots of mud. I keep my bass horn under 190hz. But the walls are not concrete and the do resonate...mud, mud, mud. I've been adding plaster, slate, even more plaster. It all helps, but when is enough, enough? The more it becomes a black hole, the more I want to rid myself of it altogether!
Once I approach the extreme, I begin to appreciate moderation...
John
If you listen to amplifiers designed by Nelson Pass, you begin to appreciate that immediacy and intimacy is much more profound than being clobbered by a horn. Subtilities are just as important as power.
When I first began constructing bass horns some 25 years ago, I noticed that driver manufacturers would make statements similar to the ones I'm making here. I thought they were plain stupid. Nothing could sound better than a horn, especiall a BASS horn. Right? Several years after becoming the owner of a horn loaded stereo system, I've come to understand that they were not stupid. I was. I suppose that the proper word is "ignorant".
Robwells: it's very easy to listen to horns from different frequencies in the sound spectrum and appreciate their similarities and dissimilarities. Folded bass horns can easily color the bass. At certain frequencies, they can make lots, and lots of mud. I keep my bass horn under 190hz. But the walls are not concrete and the do resonate...mud, mud, mud. I've been adding plaster, slate, even more plaster. It all helps, but when is enough, enough? The more it becomes a black hole, the more I want to rid myself of it altogether!
Once I approach the extreme, I begin to appreciate moderation...
John
You haven't really answered my question - If you compared 2 systems with different frequency responses then of course they will sound different. The one with the most bass will sound 'slower'.
wrt sealed systems - My last system had stereo bass 2 x scanspeak 8565-01 10" per side, crossed to mono subs 3 x 15" tempests. All sealed. Crossed at 40Hz. The labhorns equal the tightness of the scanspeaks imo. No mud..
The tempests weren't great if used above 40Hz. If used up to 80Hz they did sound muddy / boomy etc.
Thats what worries me about IB's - if you use a heavy old driver then do you get its sound qualities at 80Hz ? ie if I put my tempests in an IB will they sound the same as in their 220L cabs. If so then no thankyou to the IB philosophy.
Rob.
wrt sealed systems - My last system had stereo bass 2 x scanspeak 8565-01 10" per side, crossed to mono subs 3 x 15" tempests. All sealed. Crossed at 40Hz. The labhorns equal the tightness of the scanspeaks imo. No mud..
The tempests weren't great if used above 40Hz. If used up to 80Hz they did sound muddy / boomy etc.
Thats what worries me about IB's - if you use a heavy old driver then do you get its sound qualities at 80Hz ? ie if I put my tempests in an IB will they sound the same as in their 220L cabs. If so then no thankyou to the IB philosophy.
Rob.
Rob, we aren't comparing the same drivers. My sealed cab is using a pair of JBL 2240s. They have lighter cones, are well dampened, and basically are very powerful 18" pro-audio drivers. They sound fantastic!
I just finished doing an A/B on the JBLs vs. the Lab-12 driven 35hz goose-neck horn. Both have advantages. But when push comes to shove, I can see myself living without the horn and being very happy with another pair of JBLs in its place. The horn has earned a place in my heart, but it's just too dam_ big and ugly. If I were to do it over again, I'd construct a dog-house outside the living environment and keep the monster locked up out of sight.
Heavy cones in an I.B. do seem advantageous in the first octave only. I'll explore with the electronic x-over. It's easy to twist a knob. If the I.B. can't perform clean at 80hz, then it's cutoff will be lowered. Power and woofers are cheap these days. Living space isn't.
John
btw, Rob, the bass is EQ'd to match one channel to another. The JBLs sound pretty. The horn sounds articulate. At this point in time, I prefer pretty.
I just finished doing an A/B on the JBLs vs. the Lab-12 driven 35hz goose-neck horn. Both have advantages. But when push comes to shove, I can see myself living without the horn and being very happy with another pair of JBLs in its place. The horn has earned a place in my heart, but it's just too dam_ big and ugly. If I were to do it over again, I'd construct a dog-house outside the living environment and keep the monster locked up out of sight.
Heavy cones in an I.B. do seem advantageous in the first octave only. I'll explore with the electronic x-over. It's easy to twist a knob. If the I.B. can't perform clean at 80hz, then it's cutoff will be lowered. Power and woofers are cheap these days. Living space isn't.
John
btw, Rob, the bass is EQ'd to match one channel to another. The JBLs sound pretty. The horn sounds articulate. At this point in time, I prefer pretty.
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