As everyone knows, the WE13a are 14ft long, curled horns that play down to about 100hz.
I plan to get these going in my music room. Now the question is what should I consider for a subwoofer(s) to complement the 13a horns below 100hz.
My room is about 550sq.ft. / 51 sq.m.
Open baffle and infinite baffle bass is out of question for me. My first thought would be a single 14 ft. long bass horn, for proper time alignment. What are your thoughts on this and particularly, what do you guys think I can get out of a 14' long bass horn?
thanks,
Herman
I plan to get these going in my music room. Now the question is what should I consider for a subwoofer(s) to complement the 13a horns below 100hz.
My room is about 550sq.ft. / 51 sq.m.
Open baffle and infinite baffle bass is out of question for me. My first thought would be a single 14 ft. long bass horn, for proper time alignment. What are your thoughts on this and particularly, what do you guys think I can get out of a 14' long bass horn?
thanks,
Herman
Horn sub
I would even be happy with 30-200hz!
If that is the case, I would seriously consider going with a horn sub. It may be a single unit, placed between the
Other than modeling the horn in HornResp, which I have not used before, what would be my next step in getting this project moving along? Driver selection?
I would even be happy with 30-200hz!
If that is the case, I would seriously consider going with a horn sub. It may be a single unit, placed between the
Other than modeling the horn in HornResp, which I have not used before, what would be my next step in getting this project moving along? Driver selection?
Herman,
There are quite a few design considerations in integrating a horn system. In room measurement of the pair of the WE13a would be a good start for the project. Once you determine what the levels to match (or exceed) are, you narrow down what is required to "keep up".
Although the thread below degenerated into some personal squabbles, it also presented a number of models and alternatives along the lines of what you may be looking for, other than the construction material the OP likes to work with ;^) :
Concrete Bass Horn Design Question
Art
There are quite a few design considerations in integrating a horn system. In room measurement of the pair of the WE13a would be a good start for the project. Once you determine what the levels to match (or exceed) are, you narrow down what is required to "keep up".
Although the thread below degenerated into some personal squabbles, it also presented a number of models and alternatives along the lines of what you may be looking for, other than the construction material the OP likes to work with ;^) :
Concrete Bass Horn Design Question
Art
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Art,
thanks for the tip. That's quite a read. Only when I have the 13a horns, will I be able to measure them in my room. This is a project that will take about 6 months to complete.
The 12pi basshorns is the closest off the shelf product that I have found:
Pi Speakers, Subwoofers, 12Pi basshorn subwoofer
However, the horn path length is 9.3 feet. This is not close enough to my target of 14 feet. I suppose 12-14 would be close enough to match the horn path lengths in my listening space.
Given that design "constant" I would like to get some help when designing this horn. Anyone around here qualified for this task?
thanks for the tip. That's quite a read. Only when I have the 13a horns, will I be able to measure them in my room. This is a project that will take about 6 months to complete.
The 12pi basshorns is the closest off the shelf product that I have found:
Pi Speakers, Subwoofers, 12Pi basshorn subwoofer
However, the horn path length is 9.3 feet. This is not close enough to my target of 14 feet. I suppose 12-14 would be close enough to match the horn path lengths in my listening space.
Given that design "constant" I would like to get some help when designing this horn. Anyone around here qualified for this task?
Might have a 'close enough' design, an early Lansing/Altec 30 Hz horn designed for the original 515, which its ~functional equivalent, the Altec/GPA 515-8G sims just fine in it, though at 16+ ft needs to be shortened a bit, winding up with a ~34.18 Hz flare frequency/30 Hz/F6 according to HR:
GM
GM
No, all I did was load the details of it from the Badmaieff, Davis book "How to build Speaker Enclosures".
Not really, it only has a 1.76:1 compression ratio plus the 515's cone is quite stiff, i.e. they were designed for bass horn loading in general and the original Lansing [Altec] 515 and 8G in particular. For sure, I've loaded 515Bs at 2:1 with no audible issues at > its 35 W [continuous] rating up to 100+W transients in the mid bass/lower mids. Factor in that Xmax will limit it to ~10 W down low where it's just 'loafing' along at ~115 dB/30 Hz/2pi and have a fair amount of overdrive capability before distortion becomes obvious, so 120 dB/32 Hz for those Jimmy Smith Hammond notes seems a reasonable expectation.
If this isn't enough, there's more modern drivers with similar specs and much higher power handling, but using a driver from the same 'family' is a nice 'touch' for the W.E. horns since the multiple 18"FC woofer OB system isn't an option.
AFAIK, Hornresp calculates all the pertinent dims to build it and let's you choose height/width ratio, though if the 14 ft includes the driver box, then somewhere near the throat you'll have to put a kink in it to angle it up enough to clear the wall/whatever.
Anyway, others more familiar with this tool can help with it.
GM
Not really, it only has a 1.76:1 compression ratio plus the 515's cone is quite stiff, i.e. they were designed for bass horn loading in general and the original Lansing [Altec] 515 and 8G in particular. For sure, I've loaded 515Bs at 2:1 with no audible issues at > its 35 W [continuous] rating up to 100+W transients in the mid bass/lower mids. Factor in that Xmax will limit it to ~10 W down low where it's just 'loafing' along at ~115 dB/30 Hz/2pi and have a fair amount of overdrive capability before distortion becomes obvious, so 120 dB/32 Hz for those Jimmy Smith Hammond notes seems a reasonable expectation.
If this isn't enough, there's more modern drivers with similar specs and much higher power handling, but using a driver from the same 'family' is a nice 'touch' for the W.E. horns since the multiple 18"FC woofer OB system isn't an option.
AFAIK, Hornresp calculates all the pertinent dims to build it and let's you choose height/width ratio, though if the 14 ft includes the driver box, then somewhere near the throat you'll have to put a kink in it to angle it up enough to clear the wall/whatever.
Anyway, others more familiar with this tool can help with it.
GM
Questions and comments:
1) This doesn't matter:
You can physically time align horns of different lengths - this is stated in the usage notes for the 12pi. Just place the devices so that the path length between the sources and your ears is equal.
e.g. if the WE13a horns are 14' long, and the mouths are 6' from your head, the sound will have to travel 20' in total to get to you ...so you'd simply position the 12pi bass horns with their mouths 10.7 feet from your head, so the sound from them will also have to travel 20' in total to get to you.
2) You have a DSP, and you like it:
If yes, then it doesn't matter at all whether your system is physically time aligned.
3) If you are considering a straight sub, you must have a lot of room. So why use folded horns for the range above?
Horn folding is usually a space-saving compromise.
4) More reading. The concrete bass horn linked above never got built (AFAIK), but it prompted me to hunt for info on the (real) 15' long "artichoke" horn, which in turn prompted my own build. Info here: Artichoke Horn
Note that, for indoor use, you can scale down the mouth size, compared to these outdoor builds. That is: the length of the artichoke horn + the mouth size of my horn (4'x4') would be about right.
5) Get Hornresp and play with it. It is very good.
1) This doesn't matter:
You can physically time align horns of different lengths - this is stated in the usage notes for the 12pi. Just place the devices so that the path length between the sources and your ears is equal.
e.g. if the WE13a horns are 14' long, and the mouths are 6' from your head, the sound will have to travel 20' in total to get to you ...so you'd simply position the 12pi bass horns with their mouths 10.7 feet from your head, so the sound from them will also have to travel 20' in total to get to you.
2) You have a DSP, and you like it:
Does the DSP-6 have delay?
If yes, then it doesn't matter at all whether your system is physically time aligned.
3) If you are considering a straight sub, you must have a lot of room. So why use folded horns for the range above?
Horn folding is usually a space-saving compromise.
4) More reading. The concrete bass horn linked above never got built (AFAIK), but it prompted me to hunt for info on the (real) 15' long "artichoke" horn, which in turn prompted my own build. Info here: Artichoke Horn
Note that, for indoor use, you can scale down the mouth size, compared to these outdoor builds. That is: the length of the artichoke horn + the mouth size of my horn (4'x4') would be about right.
5) Get Hornresp and play with it. It is very good.
Hmm, a 30 Hz flare, 14 ft axial length expo horn placed between the WE horns in 2pi space requires a ~41.43 ft perimeter mouth to be flat to nearly 30 Hz according to HR, so in retrospect might not fit in the room.
So, at this point, guess we need much more dimensional details to see what can realistically be done and/or what compromises he's willing to accept such as building it as a false [rear] wall in a bi-fold layout to load either a centrally located full height mouth to get a somewhat 0.5 pi loading or at both corners with much smaller full height slot mouths and use DSP to align them.
GM
So, at this point, guess we need much more dimensional details to see what can realistically be done and/or what compromises he's willing to accept such as building it as a false [rear] wall in a bi-fold layout to load either a centrally located full height mouth to get a somewhat 0.5 pi loading or at both corners with much smaller full height slot mouths and use DSP to align them.
GM
Gees...... my memory's getting so bad, totally forgot it had a drawing.
Indeed, a lot of really good speaker 'system' design info packed in a [mostly] easy to understand format 'buried' in it and a great update to Cohen's 'HiFi Loudspeakers and Enclosures' with of course the Davis's 'Sound System Engineering' being a veritable reference 'bible' for the advanced DIYer, pro designer.
GM
Indeed, a lot of really good speaker 'system' design info packed in a [mostly] easy to understand format 'buried' in it and a great update to Cohen's 'HiFi Loudspeakers and Enclosures' with of course the Davis's 'Sound System Engineering' being a veritable reference 'bible' for the advanced DIYer, pro designer.
GM
That pic / description seems to be:
a) a light hearted bit of engineering japery
b) a 100% theoretical free space horn (with no ground plane)
The "Artichoke" horn I linked in post 9 seems a bit more sensible (a relative term!), because it uses the ground plane, so has 1/2 the mouth area of the horn in the book.
Indoors, with good placement, you could shrink the mouth down much further.
Eso (who used to post on the High Efficiency Speaker Asylum) took it to the logical limit, by building his bass horns into the room. He had stereo 30Hz bass horns that were only 9' long, because "My subs each use the room essentially as a conical mouth extention".
I can't find / remember the mouth size of Eso's horns, and the pic links are now dead ...but from memory, they were roughly chest high - much smaller than 11' by 11'
Corner placement
This 14 ft long horn will be a folded or curled type. Also, I plan to have it by at least two surfaces of the room:
wall+floor or maybe even two walls+floor. In other words, it can be close to a corner.
It may actually face the corner or face the room and be within 2ft of the corner.
So that hopefully clarifies the horns location in the listening room. Will I still need ~41.43 ft perimeter mouth?
Herman
Hmm, a 30 Hz flare, 14 ft axial length expo horn placed between the WE horns in 2pi space requires a ~41.43 ft perimeter mouth to be flat to nearly 30 Hz according to HR, so in retrospect might not fit in the room.
So, at this point, guess we need much more dimensional details to see what can realistically be done and/or what compromises he's willing to accept such as building it as a false [rear] wall in a bi-fold layout to load either a centrally located full height mouth to get a somewhat 0.5 pi loading or at both corners with much smaller full height slot mouths and use DSP to align them.
GM
This 14 ft long horn will be a folded or curled type. Also, I plan to have it by at least two surfaces of the room:
wall+floor or maybe even two walls+floor. In other words, it can be close to a corner.
It may actually face the corner or face the room and be within 2ft of the corner.
So that hopefully clarifies the horns location in the listening room. Will I still need ~41.43 ft perimeter mouth?
Herman
If folded + corners is OK, it sounds like you could just chuck a pair of 12pi (or whatever) into the corners, and be done.
For the DIY route, this is me quoting Steve Schell:
I encourage you to pursue horn loading to 20Hz. or below. The sound (and feel) you will get is closer to reality in my experience than any other type of subwoofer.
I designed the "Big Bottom" sub several years ago in an attempt to see how a long, slow flare horn would sound. The length inside the box is 20 feet, the flare rate is 15Hz. A 15" woofer drives the horn through a 67 square inch throat, about a 2:1 compression ratio. I don't know if this is close to optimal, all I know is that it works.
To conceptualize the relationship between a horn and its boundaries, I like to draw them out on graph paper as equivalent square cross sections. It is easy to plot out the horn shape by calculating the square root of the area every foot or two. Plotted this way, a plane wave expansion out of a trihedral corner is equivalent to a conical flare whose walls depart at an angle of 73 degrees, if memory serves. You can combine the proposed horn flare with the room flare and see how close the room serves as a continuation of the horn. In every case I have measured, a trihedral corner expands much too fast to maintain the expansion of the typical 30 or 35Hz. flare exponential horn. It will still help, of course.
The BB sub is built as a roughly 8' by 8' by 2' box which exhausts out one side. It sits along a wall, the mouth ideally aimed at a corner 4' away. The plane wave expansion out of a 90 degree, floor to ceiling corner (8' ceiling) actually plots out as a parabola, but nicely meshes with the 15Hz, flare, coming quite close to maintaining the horn shape out to a total length of 35' or so.
Practically speaking, the room boudaries' contribution to the horn flare is dependent on the building's construction. In my single story wood frame house, the wavelengths below 40Hz. all but ignore the structure and go where they please. My neighbors have no doubt noticed this. I would say it is best to make the horn as long as you can, use 3/4" plywood for the enclosure, and use as low a flare rate as you can manage. Even at 20', my design is only about one third of a wavelength at 20Hz., and about one wavelength at the upper limit of 80Hz.
I designed the "Big Bottom" sub several years ago in an attempt to see how a long, slow flare horn would sound. The length inside the box is 20 feet, the flare rate is 15Hz. A 15" woofer drives the horn through a 67 square inch throat, about a 2:1 compression ratio. I don't know if this is close to optimal, all I know is that it works.
To conceptualize the relationship between a horn and its boundaries, I like to draw them out on graph paper as equivalent square cross sections. It is easy to plot out the horn shape by calculating the square root of the area every foot or two. Plotted this way, a plane wave expansion out of a trihedral corner is equivalent to a conical flare whose walls depart at an angle of 73 degrees, if memory serves. You can combine the proposed horn flare with the room flare and see how close the room serves as a continuation of the horn. In every case I have measured, a trihedral corner expands much too fast to maintain the expansion of the typical 30 or 35Hz. flare exponential horn. It will still help, of course.
The BB sub is built as a roughly 8' by 8' by 2' box which exhausts out one side. It sits along a wall, the mouth ideally aimed at a corner 4' away. The plane wave expansion out of a 90 degree, floor to ceiling corner (8' ceiling) actually plots out as a parabola, but nicely meshes with the 15Hz, flare, coming quite close to maintaining the horn shape out to a total length of 35' or so.
Practically speaking, the room boudaries' contribution to the horn flare is dependent on the building's construction. In my single story wood frame house, the wavelengths below 40Hz. all but ignore the structure and go where they please. My neighbors have no doubt noticed this. I would say it is best to make the horn as long as you can, use 3/4" plywood for the enclosure, and use as low a flare rate as you can manage. Even at 20', my design is only about one third of a wavelength at 20Hz., and about one wavelength at the upper limit of 80Hz.
Not really AFAIK, I've been led to believe it was a real WE/Lansing horn, but Don Davis is still around and probably knows for sure, so anybody here on speaking terms with him? Art?
Regardless, you imply the pioneers didn't make big 'free' space horns, but they did and propped them up like this ~20 Hz, 1" throat Magnavox horn and there were other smaller ones too, but my Google link no longer displays what I originally found long ago, so for now this is all I've got: File:Large horn loudspeaker.jpg - Wikimedia Commons
Note that I posted this 'no compromise' horn as a proper period correct bass horn with the kind of comparable 'no compromise' performance as the WE13A, i.e. max efficiency/BW, but of course it can be shrunk to a much smaller size with increasing number of boundaries, just each added boundary reduces the quality of its performance in relation to the WE13A.
Frankly, without being able to compare the full size to one heavily truncated in room, I doubt anyone would notice due to how bad the room modifies a speaker's [mid] bass response. Still, if one has the space, budget, etc., to drive a full size, wide range horn system to ear splitting levels at low distortion with a single 300B tube, why compromise?
Anyway, I see he's given us more details, so will address the'shrinking' of it or some other alignment as time permits if he chooses to pursue it.
GM
Yeah, it would be a costly sucker for sure, though wouldn't surprise me if it was less than a pair of pristine WE13As.
Well, the pioneers were happy with truncated 70 Hz horns bass tuned to 35 Hz, so figure 2 octaves for the sub = 17.5 Hz works for all but some special effects recordings and movie soundtracks, which require 40 Hz horns bass tuned to 20 Hz.
That said, DSL's DTS15 comes close to the 'magic' <10 Hz goal and many have XO'd them at 80 Hz/4th, so a bit bigger version theoretically could do it with a 60 Hz horn.
GM
Well, the pioneers were happy with truncated 70 Hz horns bass tuned to 35 Hz, so figure 2 octaves for the sub = 17.5 Hz works for all but some special effects recordings and movie soundtracks, which require 40 Hz horns bass tuned to 20 Hz.
That said, DSL's DTS15 comes close to the 'magic' <10 Hz goal and many have XO'd them at 80 Hz/4th, so a bit bigger version theoretically could do it with a 60 Hz horn.
GM
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