I have been trying a number of things recently looking for a good match for my TAD 4002/ Stereolab horn system. Tired of the somewhat hooty upper bass presentation offered by my big 15 inch TL system, I decided to build the 100hz midbass horn designed by John Inlow, which looked very promising.
I took the annotated drawings posted on his site and proceeded to fill in the missing bits of information by drawing the system out full size to get my panel widths/etc., and put the whole thing together with 1/2 inch baltic birch, which apparently is not enough for the task. The resulting horns are extremely stiff, and relatively dead thanks to some 3/4 inch red oak bracing placed every 6 inches or so, added after John offered that the horns needed stiffening to perform as designed. I also cut back the 5 inches of extra width I had added to the last panels in an effort to extend the range of the horn.
Problem is: At the moment, this midbass horn has no midbass response to speak of. No slam, no punch, no… bass, really. Sounds great when the harpsichord is rocking, but the kick drums need not apply, nor the lower 2 strings of the bass guitar, either.
The woofer being used is the B&C 12PE32. The driver has an fs of 51 hz, a recommended sealed box volume of 1.1 cu ft, which will give a tuning of 85 hz. The chamber in this horn is 380 cu in, which becomes 190 cu in once the driver is installed. My best guestimate of the resulting chamber resonance is something on the order of 400 hz or so… Is this too high for a midbass horn? I can fabricate a simple baffle and measure the chamber resonance sans horn, but where should it be tuned on a 100 hz horn flare?
I took the annotated drawings posted on his site and proceeded to fill in the missing bits of information by drawing the system out full size to get my panel widths/etc., and put the whole thing together with 1/2 inch baltic birch, which apparently is not enough for the task. The resulting horns are extremely stiff, and relatively dead thanks to some 3/4 inch red oak bracing placed every 6 inches or so, added after John offered that the horns needed stiffening to perform as designed. I also cut back the 5 inches of extra width I had added to the last panels in an effort to extend the range of the horn.
Problem is: At the moment, this midbass horn has no midbass response to speak of. No slam, no punch, no… bass, really. Sounds great when the harpsichord is rocking, but the kick drums need not apply, nor the lower 2 strings of the bass guitar, either.
The woofer being used is the B&C 12PE32. The driver has an fs of 51 hz, a recommended sealed box volume of 1.1 cu ft, which will give a tuning of 85 hz. The chamber in this horn is 380 cu in, which becomes 190 cu in once the driver is installed. My best guestimate of the resulting chamber resonance is something on the order of 400 hz or so… Is this too high for a midbass horn? I can fabricate a simple baffle and measure the chamber resonance sans horn, but where should it be tuned on a 100 hz horn flare?
hmm............
I'd been told a few things on bass horns.
That driver should work fine.
But to me the bass horn seems a little small and a little shallow, even if the simulation says otherwise. 21" x 21" doesn't seem big enough.
Do I know better than horn response ? no, but there are a few rules out there that should not be forgotten. You can find formulas to find out the area of a mouth needed.
A 100hz horn (that I'd like to try someday), for enough mouth (sitting on concrete ideally), you'd need around 5ft2, or I think 27"x27". And ideally the horn length is 1/4 wavelength of 1/2 an octave lower than the mouth cutoff. So 100hz mouth would like 1/4 wavelength of 75hz, or 3.76' long (42").
And I imagine the knee is sharp, so there may seem like nothing below 100hz (no bass support). -3db @100hz with 18db rolloff would seem like no bass to my ears too. That'd be like crossing to a subwoofer but without a subwoofer connected.
And the rear chamber, that I can't help you with, but small is usually good, we arn't making a woofer box.
His 80hz horn looks better to me (26.5" x 26.5") but still a little short horn length to me at 34" deep.
I noticed that his simulation for the 80hz horn is 1pi, that would be on a concrete floor AND up against a concrete wall.
Maybe his simulation of the 100hz horn is in 1pi also................
diyAudio.com Wiki - projects by fanatics, for fanatics
Take a klipsch Lascala.
a 24" x 24" mouth, with what, under 36" of length ?
It peaks at 250 and 140hz (meaning the mouth is too small causing ripples).
http://www.audioasylum.com/forums/hug/messages/16/164241.html
It has 120hz mouth and 100hz taper rate.
Below 120hz, it is acting like a woofer in a box (horn loading not helping).
It's -10db in klipsch's concrete perfect golden ratio room with an unknown amount of room gain to make that number.
http://www.diyaudio.com/forums/subwoofers/176729-klipsch-horn-woofer-designs-2.html
Norman
I'd been told a few things on bass horns.
That driver should work fine.
But to me the bass horn seems a little small and a little shallow, even if the simulation says otherwise. 21" x 21" doesn't seem big enough.
Do I know better than horn response ? no, but there are a few rules out there that should not be forgotten. You can find formulas to find out the area of a mouth needed.
A 100hz horn (that I'd like to try someday), for enough mouth (sitting on concrete ideally), you'd need around 5ft2, or I think 27"x27". And ideally the horn length is 1/4 wavelength of 1/2 an octave lower than the mouth cutoff. So 100hz mouth would like 1/4 wavelength of 75hz, or 3.76' long (42").
And I imagine the knee is sharp, so there may seem like nothing below 100hz (no bass support). -3db @100hz with 18db rolloff would seem like no bass to my ears too. That'd be like crossing to a subwoofer but without a subwoofer connected.
And the rear chamber, that I can't help you with, but small is usually good, we arn't making a woofer box.
His 80hz horn looks better to me (26.5" x 26.5") but still a little short horn length to me at 34" deep.
I noticed that his simulation for the 80hz horn is 1pi, that would be on a concrete floor AND up against a concrete wall.
Maybe his simulation of the 100hz horn is in 1pi also................
diyAudio.com Wiki - projects by fanatics, for fanatics
Take a klipsch Lascala.
a 24" x 24" mouth, with what, under 36" of length ?
It peaks at 250 and 140hz (meaning the mouth is too small causing ripples).
http://www.audioasylum.com/forums/hug/messages/16/164241.html
It has 120hz mouth and 100hz taper rate.
Below 120hz, it is acting like a woofer in a box (horn loading not helping).
It's -10db in klipsch's concrete perfect golden ratio room with an unknown amount of room gain to make that number.
http://www.diyaudio.com/forums/subwoofers/176729-klipsch-horn-woofer-designs-2.html
Norman
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With such a extremly low Q driver the horn will drop of well above 100 Hz, try an "inferior" driver something lika a plain vanilla Emnience driver with a Q of 0.5 or so.
Or try putting a 10-20 Ohm resistor in series with your driver to increase the Qes, and try if you like this better.
The Beyma I used (Doctor Boar; DIY loudspeakers and HiFi) is similar to your driver with regard to Q and Mms.
Or try putting a 10-20 Ohm resistor in series with your driver to increase the Qes, and try if you like this better.
The Beyma I used (Doctor Boar; DIY loudspeakers and HiFi) is similar to your driver with regard to Q and Mms.
Are you running subs??? Slam comes from the combination of a strong mid AND sub signals. Here are the HR and real plots for that horn. I can see how you would think there is no slam or punch.
I had the same disappointment when I first got my Edgar 80hz horns. I could hear the low-mid music, but it had no slam. I put in a couple subs and BINGO!!!
I had the same disappointment when I first got my Edgar 80hz horns. I could hear the low-mid music, but it had no slam. I put in a couple subs and BINGO!!!
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I went ahed and dusted off the old Totem lightning sub (tiny, but reasonably capable in my small listening room), and the system has picked up quite a bit in the enjoyment department. I had originally built these horns longer, with an expanded mouth, but it was suggested that I shorten the horn back to the original profile, and the original mouth size- it was 24X24, but is now 20X20. It sounds a little more controlled now, but I guess the fast rolloff is what was getting me.
Running the numbers using the formulas published by Edgar in his show horn article gave me completely different results with regards to mouth size, throat size, and length. I think perhaps, John was looking to optimize the impulse response of the system, which he mentions specifically several times on his site. THe main thing I was looking for with this component of my system was a good match to my Stereo Lab 250 hz horns, and I think this horn does just that on the top end- I can run the midbass without crossover and get a good level match with the main horn- the sensitivities seem to line up- on paper, anyway…
If it mates well with the mid horn, that is great....half the battle really. The other half is the bottom end. Below is a pic of those horns in John's house. Notice the HUGE Tapped Horn sub behind his horns.
That is an interesting choice for driver. Normally a horn driver has a Qts of .6 or so. The B&C is .18 I wonder what John was thinking about when he chose that driver.
What crossover are you using? The MiniDSP might be a very good choice.
This is all very interesting to me as I was all set and ready to build John's 80hz horn when a pair of cabs fell in my lap. I like John's work.
That is an interesting choice for driver. Normally a horn driver has a Qts of .6 or so. The B&C is .18 I wonder what John was thinking about when he chose that driver.
What crossover are you using? The MiniDSP might be a very good choice.
This is all very interesting to me as I was all set and ready to build John's 80hz horn when a pair of cabs fell in my lap. I like John's work.
I'm a bit perplexed by this statement. The formula 2*fs/Qes is often cited as a figure of merit for a horn driver's high end. In this case, Qes (which is close to Qt, should be as low as possible to extend the high frequency response an adequate range to get up to, say 500Hz. See Edgar's show horn article. Wondering if you are confusing a horn driver with a sealed box driver. Two different animals.
OK Pooge, you got me thinking. I have two 12" drivers I got some time ago and the fs is 18.84hz, the Qes is .4642 so using your formula of 2*fs/Qes I get 81.17 What does that represent? Is it 81hz or I don't know. Here is a screen shot of the woofers from WT3. Would these work well in a horn?
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They wouldn't be good mid-bass horn drivers.
That formula is basically a figure of merit formula to get an idea how high in frequency it is usable.
So low fs is not that desirable. You want a highish fs, up to but under the lower crossover frequency, a low Qes, e.g., <.3, and a high BL factor above 20 or preferably higher, i.e., 23-30, which together indicate a whopping magnet and light cone able to work against the high acoustic load of the horn, i.e., against pressure.
Those drivers specs would indicate a sealed box use.
That formula is basically a figure of merit formula to get an idea how high in frequency it is usable.
So low fs is not that desirable. You want a highish fs, up to but under the lower crossover frequency, a low Qes, e.g., <.3, and a high BL factor above 20 or preferably higher, i.e., 23-30, which together indicate a whopping magnet and light cone able to work against the high acoustic load of the horn, i.e., against pressure.
Those drivers specs would indicate a sealed box use.
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I am not currently using any kind of crossover, save the very simple passive one I have on the midrange horn, which is just a single capacitor, and a couple resistors to provide the small amount of attenuation needed. I have really top notch electronics, and I have no real desire to run everything through a processor, so I'm purely old school.
My sub (when I build it) will run on a separate amplifier, with an electronic tubed crossover- passive filters. I'm going horn loaded there, too- probably a straight exponential monster of some sort with these little Faital 15 inchers I've been using in my TLs.
I want to go all horn with this system, because one of my speaker building engineer friends calls the idea of horns ridiculous. He refers to them as "acoustic amplifiers", which in itself shows his complete lack of understanding as to how they actually work. He also owned and modded a pair of VOTs in the 70s, so he's "been there, done that" with horns- since they all sound like the VOT, of course…
So I'm doing this because I love horns, and because it'll **** that guy off righteously.
-And my system can play things that would bring his lil' sealed box babies to their KNEES.
What was the outcome?
Having just battled a Hyperbolic profile mid bass horn over the weekend - I wondered what happened to this project?
I have a ~30lt - diver rear chamber, this is with a Kappa 15A. 30lt is very close to 1.1 cuft
I have to fiddle with the volume I think. Easy to extend the chamber if needed.
Having just battled a Hyperbolic profile mid bass horn over the weekend - I wondered what happened to this project?
I have a ~30lt - diver rear chamber, this is with a Kappa 15A. 30lt is very close to 1.1 cuft
I have to fiddle with the volume I think. Easy to extend the chamber if needed.
I am not currently using any kind of crossover, save the very simple passive one I have on the midrange horn, which is just a single capacitor, and a couple resistors to provide the small amount of attenuation needed. I have really top notch electronics, and I have no real desire to run everything through a processor, so I'm purely old school.
My sub (when I build it) will run on a separate amplifier, with an electronic tubed crossover- passive filters. I'm going horn loaded there, too- probably a straight exponential monster of some sort with these little Faital 15 inchers I've been using in my TLs.
I want to go all horn with this system, because one of my speaker building engineer friends calls the idea of horns ridiculous. He refers to them as "acoustic amplifiers", which in itself shows his complete lack of understanding as to how they actually work. He also owned and modded a pair of VOTs in the 70s, so he's "been there, done that" with horns- since they all sound like the VOT, of course…
So I'm doing this because I love horns, and because it'll **** that guy off righteously.
-And my system can play things that would bring his lil' sealed box babies to their KNEES.
I am also shopping for DIY midbass horns.
Silly of you not to use a sub from the start. But I did the same mistake. You can't listen properly without something extra below 80 or 100 Hz.
I am using a 12" JBL 2202H, that someone else tried in a midhorn and said they were not all that crisp as this. So I changed the dustcap to an aluminum one last night, and it sounds a little better actually. I will go ahead and build a smallish back chamber, and possibly also a phase plug, and see how that goes. What I want to do is to finish a build of a larger horn, because I believe these type of 12" drivers have more to bring to the table. Maybe I will go 15" or 18", but I fear I will lose an edge. To me, those big drivers (15"-18") seem to be a excuse for making a too small midbasshorn that will still have signal at 80Hz. The signal will probably not be hornloaded closer to 80Hz, or even 100hz, just above 200Hz. But I am just guessing, until I finish my larger builds.
I found this in a another forum where a guy called Andy was comparing the JBL 2202H and the B&C 12PE32. I do get the sense that the JBL 2202H really has a too heavy cone, which is also clear reading the parameters.
"Hi nutters
I'm currently using B&C 12PE32 as midbass with front horn and bassreflex rear. Midrange is quick and enuff clear, midbass not muddy. x/o points 120 & 1230Hz, both 24LR.
Could be using 2*12 per cab to get more kick (and dead weight, choose wisely?...). I haven't heard the 18sounds 12ND710, but by the parameters they could serve well (in horn). I'm anyway satisfied with B&Cs performance. Good bang for the buck.
Previous mids in same cabs were the JBL 2202H, they needed lower LP (800Hz) and still not so clear sounding, maybe the larger Mms was the culprit, despite the angrier BxL.
Andy"
Silly of you not to use a sub from the start. But I did the same mistake.
You can't listen properly without something extra below 80 or 100 Hz. I am using a 12" JBL 2202H, that someone else tried in a midhorn and said they were not all that crisp as this. So I changed the dustcap to an aluminum one last night, and it sounds a little better actually. I will go ahead and build a smallish back chamber, and possibly also a phase plug, and see how that goes. What I want to do is to finish a build of a larger horn, because I believe these type of 12" drivers have more to bring to the table. Maybe I will go 15" or 18", but I fear I will lose an edge. To me, those big drivers (15"-18") seem to be a excuse for making a too small midbasshorn that will still have signal at 80Hz. The signal will probably not be hornloaded closer to 80Hz, or even 100hz, just above 200Hz. But I am just guessing, until I finish my larger builds.
I found this in a another forum where a guy called Andy was comparing the JBL 2202H and the B&C 12PE32. I do get the sense that the JBL 2202H really has a too heavy cone, which is also clear reading the parameters.
"Hi nutters
I'm currently using B&C 12PE32 as midbass with front horn and bassreflex rear. Midrange is quick and enuff clear, midbass not muddy. x/o points 120 & 1230Hz, both 24LR.
Could be using 2*12 per cab to get more kick (and dead weight, choose wisely?...). I haven't heard the 18sounds 12ND710, but by the parameters they could serve well (in horn). I'm anyway satisfied with B&Cs performance. Good bang for the buck.
Previous mids in same cabs were the JBL 2202H, they needed lower LP (800Hz) and still not so clear sounding, maybe the larger Mms was the culprit, despite the angrier BxL.
Andy"
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Corvus corax:
I am no expert but IMHO you need a mid bass horn that goes down 80hz at least. That extra 20hz lower cut off means a great deal. Bigger is better for sure. I am sure you know that DR. Bruces' favored driver for his mid bass horn is the EV 15b.
If you are getting a good match to your mid horn that is a major plus !
The best mid bass driver ever made IMHO is the Altec 515b. Great plains Audio makes an "identical" copy of the original. One or 2 of these drivers per side in a large box will knock you off your chair on good drum hits. These drivers can easily go up to 400+ hz with high efficiency and the best low midrange. Some people would try to push these drivers into subwoofer territory and that is NOT what they were designed for. For mid bass duty they are "king".
Hope this helps,
Joe
Good luck
Joe
I am no expert but IMHO you need a mid bass horn that goes down 80hz at least. That extra 20hz lower cut off means a great deal. Bigger is better for sure. I am sure you know that DR. Bruces' favored driver for his mid bass horn is the EV 15b.
If you are getting a good match to your mid horn that is a major plus !
The best mid bass driver ever made IMHO is the Altec 515b. Great plains Audio makes an "identical" copy of the original. One or 2 of these drivers per side in a large box will knock you off your chair on good drum hits. These drivers can easily go up to 400+ hz with high efficiency and the best low midrange. Some people would try to push these drivers into subwoofer territory and that is NOT what they were designed for. For mid bass duty they are "king".
Hope this helps,
Joe
Good luck
Joe
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