Folded horn speaker design – explanation and calculator
How does a folded horn speaker design work?
The folded horn speaker design is a particular case of a normal horn design. Horn’s main purpose is to increase the efficiency of a speaker. You might of done it as kid : fold
a piece of paper into a cone shape and shout through it, so it sounds louder. This is a rudimentary example of real life horn. Other, more sensible examples, are the trumpet or the trombone. These horns are easily made for high and mid frequencies, because the horns have acceptable sizes.
If you go down in frequency, the wavelength increases and so the dimensions of the horn. This is where the folded horn subwoofer comes into play. Folding the horn makes for an efficient use of space, and therefore makes the enclosure more acceptable size. A real life example would be the tuba, which is a brass instrument for the low notes. It is using a horn, but not a conventional one, like the trumpet. The tuba’s horn is not straight, it is a snail shape, to efficiently use space. A horn loudspeaker is designed to go from a small opening to a large opening. I can make it straight or folded, but the principle must remain the same.
Before we get into the folded horn speaker design, we first must understand the basic horn principles.
How does a horn loudspeaker amplify sound ?
The basic principle on which the horn relies on is impedance matching. The speaker is a mechanical system, which has a high impedance, versus the air, which has a low impedance. When a wave propagating in a tube, meets an abrupt change in acoustic impedance, part of its energy will be reflected back. Horns are not tubes. They have a certain taper. The duct or tube is progressively increasing in its cross section. Because of this taper or flare, the horns act like an impedance transformer (aka coupler). They make a smooth transition from the high impedance of the cone, to the low impedance of the air.
Now that we explained the principle on how the horn works, let’s enumerate the reasons why you would want to couple a horn to your speaker :
- Highly improved efficiency.
- Eliminating the resonance introduced by speaker boxes.
- Increased directivity. The sound doesn’t spread as much, like with normal radiating speakers. Depending on how the horn is designed, the sound is directed into certain areas. This can be a good or a bad thing, depending on the application.
- Reduction of speaker generated nonlinear distortion.
Parts of a horn speaker
The horn is composed of 3 main parts :
- The throat : which is the part that is connected to the speaker.
- The neck : which describes the length of the horn.
- The mouth or the bell : which describes the end part of the horn, “connected” to the air.
A horn will start expanding, starting from the throat and end at the mouth. The speaker will be connected at the throat of the horn, and radiate sound at the mouth of the horn. All of these parts influence how will the horn affect the overall sound. The flare and mouth design, the phase and direction of the particle velocity at the mouth, will all have an impact on the sound quality and directivity of the horn.
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One of the main characteristics of the horn is its shape. The horn has a certain taper, which is determined by the cross section expansion rate. The cross section area is determined by a function of distance, from the throat of the horn along its axis. This function will give the neck of the horn a certain shape. This means that the neck can have various shapes, but there a few shapes which are most common.
Horn profiles
Here are some common horn profiles :
- Parabolic : Easy to design and construct, but poor impedance conversion.
- Conical : Easy to design and construct, but poor impedance conversion.
- Exponential : Good wide band impedance conversion, but some nonlinearity.
- Hyperbolic : Very good and high impedance conversion, but relative nonlinearity.
- Stepped : High impedance conversion. Nonlinearity depends on step resolution. This shape is not like the others. The horn is not growing in a smooth fashion, but in abrupt square steps (imagine a cube, then a larger cube, and so on. The speaker plays through these cubes)
When you are designing a horn, you will look for 3 things : Transfer function, acoustic impedance at the throat and nonlinear distortion. There are other things to worry about, like directivity, phase distortion and resonance characteristics, but those are secondary. The latter properties can be determined by altering the length of the horn and the shape of the mouth. Because of this aspect, conical and parabolic shaped horns are not so popular.
On the other hand, exponential horn profiles are very popular, since they have good bandwidth, relatively low linear distortion and suitable throat impedance characteristics. Hyperbolic expansion gives a response down to a lower frequency value, compared to exponential, but the fall-off below that particular frequency is steeper. Also, because the expansion from the throat to the mouth is more gradual, pressure builds up inside and may cause distortion issues.
How to design a horn
Because of the impedance difference of the speaker system and that of the air, that transfer from the speaker to the air is very inefficient. The efficiency is somewhere around 1% or less. The horn is like an interface from the cone to the air, to match the impedance difference, and prevent internal reflections. A folded horn speaker design can improve efficiency by up to 80%
The design of a horn is complex, but I’m going to give the basic guidelines to keep it simple and easy to understand. No one wants to see walls of text with math formulas.
Throat diameter
- When choosing the diameter of the throat, keep in mind that the shortest wavelength reproduced is twice the diameter of the throat. So for high frequency response, the throat needs to be as small as possible. Example :
- For 10 000 Hz -> the throat needs to be 17 mm maximum.
- For 15 000 Hz -> the throat needs to be 11.3 mm maximum.
- For 20 000 Hz -> the throat needs to be 8.5 mm maximum.
Mouth diameter
- The diameter of the mouth will dictate the low frequency response. For the horn to radiate a certain low frequency, the mouth needs to be half the size of the wavelength of that particular frequency. So for good bass response the mouth needs to be as big as possible. Also, the lowest frequency played by the horn sets the resonance frequency for that horn. Example :
- For 100 Hz -> the mouth needs to be 1.7 m minimum.
- For 50 Hz -> the mouth needs to be 3.4 m minimum.
- For 20 Hz -> the mouth needs to be 8.5 m minimum.
Length of the neck
- This length is given by the mouth of the horn. If you want the mouth to have a certain diameter, the horn’s neck will have a set length. Here is a formula, how to calculate the length of the neck, considering the growth of the cross section area is exponential :
-
- A = aria of the mouth (cm2).
- a = aria of the throat (cm2).
- f = lowest frequency.
- L = length of the neck.
Example : Let’s say I have an 8″ (20 cm) woofer and I want it to go down to 50 Hz
- Let’s say, for argument’s sake, that the throat is equal to the diameter of the woofer, so the area will be πR2 = 3.14 * 102 = 314 cm2.
- The diameter of the mouth needs to be 340 cm, so it can reach 50 Hz, so the area of the mouth will be 3.14 * 1702 = 3.14 * 28900 = 90746 cm2.
- f = 50 Hz.
- Length = (log(90746) – log(314)) *4000 / (0.4343 * 50) = (4.96 – 2.50) * 4000 / 21.72 = 453 cm.
Sometimes the area in front of the driver may be smaller than the actual size of the driver. This means that this area will start to narrow, to provide a small throat, for better high frequency response, and then it will start to progressively get bigger. Because of this, a region with high pressure is born. This pressure is equalized by the sealed chamber behind the cone, which reduces non-linear distortion.
Folded horn speaker design
We have determined that the size of the horn is in direct correlation with the frequencies we want to play. This means small and medium sized horns for the high and mid frequencies, and large horns for the low frequencies. It is impractical to build a horn with a mouth of 3.5 m in diameter, because it will probably fit nowhere. So for those horns, which we want to go low, below 100 Hz, a folded or coiled designed must be adopted.
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Low frequency horns have to be extremely large, so folding the length of the horn makes the enclosure fit into a more practical space. By folding the horn, you will compromise the high frequency of the system (mid-bass). However, this aspect shouldn’t be an issue for subwoofers, since they play only the low octaves anyway.
Common folded horn subwoofer designs
The folded horn speaker design has an endless amount of possible internal layouts. The main focus is to increase the area of the flare at an exponential rate. How you fold the horn is up to your imagination. However, the folded horn speaker design is not something new. There are a few types which are quite popular :
- The W-Bins – This type of folded horn has a few variations of it own. Like any other low frequency folded horn, it has a limited frequency range and a degraded smoothness of frequency response (published specs usually smooth out the ripples in the curves). Nevertheless, the “compact” size of the W configuration is worth this drawback.
- The Scoop – this type of folded horn is similar to a transmission line. The front waves are direct radiating and the back waves are coupled to fairly long folded horn. The mouth of the horn is firing in the same direction as the front waves. This has a very good low frequency response, because of the long horn, and an extended response few octaves above, because of the direct radiating front waves.
- Bent horn – this is another typical style horn but with a shorter length.
Applications
The folded horn speaker design is a popular choice for outdoors or for very large rooms. The main reason is because they have very high efficiency and the designer can control the directivity of the sound. The size of the enclosure is not much of a problem, since they are for outside use. However, home audio is no stranger to folded horn speaker design. A rear loaded design, with a folded passage of increasing area formed behind the driver. Construct the passage using wooden panels in various configurations, to make the area exponentially larger.
Place the enclosure in a corner, and the room walls and floor serve as the final part of the flare, thus eliminating the need of making the box huge. The enclosure is not perfect, as the progression is roughly exponential and the length is short, so internal reflections can occur. Even so, efficiency of 40% is not unlikely with a folded horn speaker design. This is much more, compared to typical infinite baffle enclosure, which has around 0.5% efficiency.
Conclusion
Using a horn as coupler to a speaker, will bring several advantages, like : allowing good control of wave front properties, easy to manipulate the direction of sound, and high acoustic power over a wide frequency range. On the bad side of things, horns will present a resonant, dispersive, and nonlinear wave propagation. Because of these negative points, horns aren’t very popular in the present day. Their high efficiency is not so attractive either, since amplifier power is easy to come by these day (cheap watts). However, they are still popular on outdoor audio systems, where efficiency and directivity are important factors.
References
- Newnes Audio and Hi-Fi Engineer’s Pocket Book by Vivian Capelm (Elsevier, 2016). (Amazon affiliate link)
- Electroacoustic Devices: Microphones and Loudspeakers 1st Edition by Glen Ballou (Focal Press, 2009). (Amazon affiliate link)
- The Sound Reinforcement Handbook 2nd Edition by Gary Davis and Ralph Jones (Yamaha, 1988). (Amazon affiliate link)
- Image source : link.
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65 comments
?? For 100 Hz -> the mouth needs to be 1.7 m minimum. that’s almost 6 feet across??
Yes. That’s why you see horns mostly for tweeters.
thanks. I’m doing some front loaded 12 / horn cabinets for PA.
Salut Marius
Poti te rog sā-mi explici de ce, de exemplu Klipsh Jubilee, conform specificatiilor, redā pânā la 18 Hz? Dupā teoria expusā de tine un horn care sā coboare pânā acolo ar trebui sā aibe o dimensiune imposibil de încadrat într-o camerā. Multumesc mult
Mihai
Twenty years ago I was given a built-in tube Hi-Fi/ Stereo component system that was installed around 1960. The cabinet was custom-made with a blond finish and was set flush in a wall. It had a Voice of Music amp, am-fm tuner, Webcor turntable and Quam co-axial speakers (10.5″ woofer, 3″ mid-range, 9″ horn tweeter) that used a scoop horn. The horn mouth was 9″h x 8″w with the 9″ x 2.5″ tweeter horn set at the top. The system didn’t work at the time (needs a few tubes) but was told it had great sound quality and could be played loudly without distortion. The new homeowner told the carpenters to remove it in one piece but unfortunately they hired a wino to do the demolition work and he tore apart the cabinet to get it out. I retrieved the amp, tuner, turntable and speakers w/faceplate from the dumpster. The cabinet was assembled with glue and screws so was a total loss. I packed everything inside two large boxes and set those inside a closet to fiddle with later then forgot about them. Just discovered them recently and decided to build new scoop horn speaker cabinets using 3/4″ particleboard from an old entertainment center and bent 3/4″ plywood. The drawing of the scoop horn is practically identical to what I recall seeing a few decades ago so will copy it’s design. The paper woofer and midrange still sound pretty good without being inside a cabinet but will buy new horn tweeters since those are missing for some reason.
That my friend is an awsome old school tube system that toay, audiophiles would drool over. the power and sound of a tube amplification is unmatched by the newer electronics. Matching the scoop horn assembly that it previously had will make the most critical perfectionist listen for a long time. There is nothing like relaxing and listening to your favorite music threw a perfectly designed system that you brought back to life yourself, and knowing no body else has it.
Tube systems are nice sounding but will not outperform a mosfet amplifier on it’s best day the reason they are liked so much is they are class A amps as opposed to class AB solid state units !!
My dad had a friend whose hobby was hi fi, and in the 60’s this friend built a horn speaker cabinet. As I remember it, it was abut 1500mm on a side, pretty much cubical and with a 3-D development of the horn. The horn was of tinplate with little tags soldered on and the rest of the cube outside the horn was filled with concrete. So there could be no extra vibrations, but it was too large and too heavy for his living room, so it stayed in his workshop. Then I heard tell of another enthusiast who when he built a house had a cell built at the top of his driveway to house the speakers and the horn was then developed under the driveway to exit in his auditorium under the house. One wall was the mouth of the horn.
I came across this post looking for a design for a traditional hearing trumpet, and this helps. Thanks for posting it
Mid 70’s my brother huilt two scoop horns with a 32cm woofer and 2x a classic sqaker and 2x a Dome tweeter. 2x 35 Watt was largely sufficient to drive thé speakers outdoor for hifi parties. Speaker heights 2.50 meter. Cabinets could be horizontally split in two halves.
Hi.
I want to mention about back(rear) loaded exponential horns.Do you think designing these can be easier than designing TL??When I looked at Martin j.king documents,if we can choose tuning frequency and coupler chamber volume(he shows a Formula that coupler Volume should be bigger than some Value depending of tuning frequency) it is kind of more possible than TL??
A rear load horn would be much more difficult to design and build. TLs are rather easy to design and to build. The problem with TL’s is that you cannot predict the result. You will definitely have some problems with upper frequencies, which you will have to minimize using dampening material. You will have to play with different materials of different quantities/densities. Trial and error until you get it right.
Very good site you have here but I was curious if you knew of any forums that cover the same
topics talked about in this article? I’d really like to
be a part of community where I can get advice from other knowledgeable people that share
the same interest. If you have any suggestions, please let me know.
Thanks a lot!
you can try diyaudio.com forums
Pete- I’d try Klipsch community site and Altec community which I believe is part of Great Plains Audio site. These sites are populated by very informed folded horn fanatics that know as much as the above vintage horn manufacturers.
Yes.
thanks for the great article. Would you be interested to help building the ultimate outdoor bass horn with 16 x 18″ woofer (per channel) made by concrete?
No, sorry.
Hi Wolfgang, I have designed a few horn speakers and subwoofers in the last year, maybe i can help you. Just add me on facebook: https://web.facebook.com/mou88
Are you from germany as your name implicates?
I wanted to write years, my first horn i calculated in 2011
hello Wolfgang,
I have designed and built a similar horn… concrete… 10 m length… mouth 7m x 2.5m… I am always happy to talk about large horns… :^)
peace,
jeffrey
Great article. And your website seems full of useful information.
I’m a Product Designer looking to develop some high spec. hi-fi speakers. I want to create something that Audiophiles such as yourselves would pleased with.
I have no experience in this field, but that’s typical of most new projects I take on, and I expect the development to take much time.
I have noticed that horn speakers seem to have made a bit of a comeback amongst audiophiles. Do you think this is a good place to start?
I may get to the point where I get some funding for this development project; in which case I would be looking for a paid consultant. Is that something you would be interested in?
Thanks
Thanks Matt
Horns were popular in the past because they gave a lot of extra efficiency. Since amplifiers were weak back then, it was a must to have an efficient speaker. Nowadays, watts are easy to come by, and this is not an issue anymore. However, horns are also popular for their directivity. They are used in open baffle setups, where a lot of cancellation occurs and room response is minimized as much as possible. The horns are used to direct the high frequency sound to the listener. Basically creating a listening sweet spot, regardless the room you place them in. On the downside, you have to sit exactly in the sweet spot for best results.
Regarding your project, I’m pretty much in the learning phase myself. I progressed a lot in the past couple of years, but I still have the feeling I barely scratched the surface. If you start your project, you can shoot me an e-mail with what you have in mind, maybe I can help.
There is a little more to it than that. Horns offer higher sensitivity, as well horn are usually made with high efficiency drivers, which means less demands on the speaker and amplifier which can lead to extremely clean and accurate reproduction.
Most good horns can get very loud with less than 5 watts and be very clean at the same time. With just about any amplification in a home setting proper horns should be loud enough for anyone and still have plenty of headroom. Solid state equipment may tend to have a “harshness” to the highs especially after long listening sessions unless the amp has some what rolled off treble. I would recommend at least a tube amp on the highs/mids and your choice on the bass.
I’m using this info for a silly project make a horn for a small battery speaker system I use juggling in the park. Its extremely illuminating, thank you so much.
I wonder if anyone here can help me understand how my options (limited by materials and portability), would affect sound quality.
My main problem is not being able to go long enough to match my potential (and desired) mouth/throat.
1) If I understand correctly, I could truncate the throat end and lose mid-high amplification because of the larger throat?
2) But what if I just keep the mouth and throat sizes I want and just made the length half what it should be according to the length calculator provided? Distortion? Weak volume amplification?
Thanks in advance
The horn is actually an impedance coupler. Let me try to explain this. The speaker has a high mechanical impedance and the air doesn’t. When it transfers the energy to the air it suffers this sudden impedance change, and the transfer is inefficient. To make the transition more smoothly / progressive, you try to increase the impedance of the air (at first). This is my making the speaker radiate into a small space (the throat). It will have a hard time doing that. Bass will have some difficulty (high impedance) passing through the throat, but high frequencies will not. So you have to make the throat smaller and smaller if you want it to work for high frequencies. Then, the horn gets bigger and bigger, therefore the impedance is lower and lower until it matches the impedance of the air. This smooth transition makes the speaker more efficient. So yeah, if you make the horn shorter and throat smaller you won’t have the full benefit.
Marius, great article, thank you! I was curious where the proportions came from and the equation for calculating the length of the throat. Thank you again
At the end of the article the are some references. If I remember correctly, it’s the first book listed there.
It’s a productive learning experience
Thirty years ago, I was very young and was ignorant of folded horns, but I developed an acute ear for good sounds (without elaborating, it got me scholarships to Tanglewood and BU). For fun I was building cabinets for reclaimed speakers from an old console. 2-12″woofers,2-5″mids,2-1.5″paper cone tweets. I was in the mood to do something different so, by chance, chose a pyramid for the cabinets. Limited materials dictated the size. The pyramids we’re 24″at the bottom on any side, and 48″ long on the height. All the speakers were on the same side and I reused the passive x-overs that were in the console. I left the bottoms open for lack of wood knowing they would be placed on carpet with padding. I wasn’t expecting anything special, but the results were mind boggling. The highs and mids were a given because the frames we’re sealed. The lows we’re astounding,dynamic, accurate and had a roll off that sounded bottomless. I had to get rid of them or get evicted. I tried different scale speakers and cabs with bad results and didn’t know why. Now I know why although with that knowledge I opened a can of worms.
I’m gonna try to calculate, fold, and reproduce that simple four foot horn, this time with the speaker at the Apex of the horn.
This is fun and rewarding, thanks for the formulas and education.
i have built a dual 12 w bin specs are 15.5″x35.5″x18″. it goes down to 59 hz . resonates in 124hz and upper cutoff is 1123hz. sorry i cant post picture here. mail id: sant.demo@rediffmail.com
First of all: very clearly explained. Easy to follow but a lot of useful information. I tried to calculate the length of a horn with the following numbers but the answer looks kind of weird:
Throat 17mm (226.98mm2)
Mouth 425mm (141862.54mm2)
Frequentie 400Hz
((log(141862,54)-log(226,98))x4000)/(400×0,4343)=64,38
When I use these numbers the answer is 64,38mm. That sounds quite small for me. No need to fold 6cm ;).
Does someone know what I am doing wrong? (impossible dimensions, wrong formula)
Hello
The formula uses cm, so :
((log(1418.6)-log(2.27))x4000)/(400×0,4343)=64.37 cm
Hello,
Thanks for your reply! I had another question. For low notes, you need a very big horn. Why doesn’t a low brass instrument have a horn of a meter? And is there some kind of hack to make it smaller and still be able to bundle the low frequencies?
The same for a subwoofer. Most of them don’t have a horn of meters in diameter. Is that because the very low frequencies on an electric way already are boosted, or is there something else in the horn design?
Some instruments use very long horns as well. Like the tuba. But it’s all coiled up to save space (folded horn). Despite this, it’s still small compared to the numbers from calculations, when you try to hit the very low notes. This means that the instrument inherently doesn’t go very low in frequency, or that the horn is effective only for the upper frequencies.
Thanks for the quick reply. So what does the length of the horn do? When you should calculate the length of the horn of a tuba with the formula, is the answer close to the real length?
In my calculation, the horn length is just a bit more than the horn diameter.
What I mean is, if you have a specific measure for the mouth and the throat. Is it always one specific length what is perfect for bundling the sound or does it also depends on the application? (tuba or speaker for example)
Sound acts in the same fashion regardless of application. The horn needs a specific length for the wave to progressively build up. It’s like starting your car in 5th gear versus going 1-2-3-4-5.
Hi There,
The calculations are obviously for circular horn. Can I trade diameter for width and use these calc’s on a square mouthed horn, with the height defined by myself?
Many Thanks!
You could do that, yeah. If you want to be more rigorous, you can check that the area of the circle matches the area of the rectangle.
I am interested in making a horn for a special non-acoustical application related to fluid flow. Is there a way I can find out the radius of curvature needed for a 2.5 cm throat and 5 cm mouth. The application is related to flowing a mixture of a gas and solid from a round throat to a rectangular mouth. the neck length should be between 25 to 30 cm. This curvature is needed for the machine shop. I can discuss the need in private emails. Thank you
From what you are explaining, this is now a basic geometry problem. The curvature doesn’t have a radius because it doesn’t follow the specs of a circle. It’s simply a function (exponential, hyperbolical etc), depending on the type of the horn.
Quick question. I recently purchased a B-52 v3 subwoofer and it sounds great. Just wondering if I can lay it on its side to fit in a small church venue due to size restraints? I understand its a folded sub but did not know if that affected turning it on its side?
Shouldn’t matter that much. I mean, some horns are thought out to be placed conveniently near a couple of walls, to “continue” the horn using the walls. But you are just placing it on the floor and relying only on the horn of the enclosure itself. So it shouldn’t matter that much how you place it. It will sound mostly the same. Even if it doesn’t sound as good, there are size restraints, and you have to accept that compromise.
I do not know whether it’s just me or if perhaps everyone else encountering issues with your website.
It looks like some of the text in your posts are running off the screen.
Can somebody else please provide feedback and
let me know if this is happening to them as well?
This might be a problem with my web browser because I’ve had this happen before.
Thanks
I checked on both mobile and desktop and it works fine.
Many thanks for your informative article. In 1973 I worked for a company in Bromley called Lowther, building the cabinets and fitting the loudspeakers to them then testing prior to despatch for a clean and linear frequency response from each assembled unit.
We used a sweep signal generator connected to the loudspeaker unit and swept the output from inaudible low to inaudible high, making sure that no distortion occured, by ear.
We made just the one type of cabinet, if I remember rightly they were designated LS6 and were rated at 6 watts rms input. A co-worker there owned a pair of these on his hi-fi system and they sounded superb. I’m now working on a small version of the same idea using re-claimed/re-cycled ex-computer Harmon-Kardon drivers with a car stere DAB radio and cd player. Limitations of practical size mean the unit will not be otimum but your information here will help me in getting the best possible results.
Thanks again.
Optimum, not ‘otimum’. Sorry. Typo error.
I am considering to build a 8 inch hornloaded low mid cabinet with wide dimentions of 50cm to match the bass cabinet.
I am using inside the mouth a conical 1 inch compression driver.
Start frequency will be around 120 Hz
Any suggestion about dimentions of the horn from driver opening to mouth?
Thanks in advance!
Pascal
if your horn is 1″ at the throat and 50 cm at the mouth it will be good for 350 – 7000 Hz. Something like 25-30 cm in length should be adequate.
If you want it to for 120 Hz it needs to have a mouth of 1.4 m in diameter.
Hi Marcus! Great article! Completed all of your courses on Skillshare aswell, great material! I’ve got one question, do you know how to sim a stepped horn? I’ve tried with hornresp, but there doesn’t seem to have a stepped horn option there. I want to try designing a mini scoop but avoiding weird angles when folding the horn, just to keep it simple (there seems to be an agreement on that mini scoops are just bass reflex designs, so I thought going for a bass reflex with kind of a laberynth port with different vent withs / stepped horn should’t make a big difference on low end and SPL vs. going for a normal horn)
I haven’t really studied transmission lines and horns that much and therefore I have no idea how to use hornresp. I have to start to learn how to use it. I’m sure there is a way to model it, so maybe try on the diyaudio forum to ask for help.
Ok! I’ll try asking the guys on diyaudio! And sorry for misspelling your name Marius!
I have a nagging issue with the JBL C34 (scoop) folded horn. As a kid, I spent endless hours at my friend’s home listening to these systems. The bass was astounding. Perfect reproduction of turntable rumble and a solid “thump” when the stylus entered the lead-in groove. Now, 60 years later, I purchased a very presentable pair of C34’s and was completely disappointed at the lack of solid low bass. So I opened the cabinets and looked at the 130a’s. 60 years old but didn’t look bad. Then I noticed that the bass speaker chamber was padded not only on the back, but the sides and top. The C34 instruction/construction page says ” Fasten 1 inch of padding to the back panel”– ONLY, not top or sides. Which is right? Padding on just the back panel or also the back, top and sides? It seems as though the factory put in the extra padding.
I don’t know which variation of padding is correct, however, I doubt that some extra padding will influence the bass response in such a drastic manner.
Many thanks for your reply. It begs the question, all other factors aside, do old woofers lose their “woof”? The only answer left is the deterioration of the speakers. (I replaced all caps in the crossover with precision parts and the iron core choke with a precision air core one.) The cabinet is fine–The reduction in bass is unmistakable–not enough oomph out of the horn. Maybe softening the edges of the stiff paper cone or replacing them with cloth would lower the resonance point. I’m unsure what to do next. Thank You again.
The surround is usually the first one to degrade. Furthermore, there might be air leakage through the cone itself. It’s 60 years old. It would have been a miracle if it would still work perfectly.
I just joined this website. I think it is very , very instructive. I have enjoyed every comment and every answer and learnt a lot. Many thanks for having this very formative site.
1.Using 8″ woofer how will a hybrid system Bass reflex with tube followed by a horn of say 8″x4″ and about 8″ length response ?
2. Can one mount a midrange and tweeter on a horned speaker ?
Can anyone give me a link or Diagram for a Scoop for 12 or 15inch to play down to 30 hz.
How is it the Cerwin Vega claims their L-36 earth quake bass folded horn can do 35hz in half space placement? The diameter of the mouth is nowhere the 1/4 wavelength needed to launch the frequency.
Well, there are several reasons. First of all, the 35 Hz spec is at -10 dB, so it basically doesn’t play that low. Secondly, the speaker might play low without the horn. So, even if the horn might not be designed for very low bass, the speaker might play low regardless. Environment also plays a role, as clever use of surrounding walls might “extend” the horn flare.
Hi, help me please with an 8″ mid range, i want to use that driver between 500hz-3500hz, can yoou calculate the horn for me please, i m a little confused.
Hello
Which software can use for horn loaded subwoofer enclosure designing or measure dimensions
You can use Hornresp. A word of warning: it’s not user friendly 🙂
Hi thanks for these informationa
I’m trying to make a folded horn. We want to use it for a 36 mm 2 w speaker. And I’m not sure like how much a 36 mm speaker can be louder by using a folded horn and should I choose another speaker? Because I want to use a small one which doesn’t lots of energy. Also if I want to build one for this speaker what are the sizes of folded horn ahould be?
I’ve always been curious about something, what is the natural cutoff frequency, Fc, of a normal corner of a room, as if the corner were viewed as a horn formed by the walls? A corner formed by 3 right triangles at its apex, so 1/8th space loading, forming a trirectangular tetrahedron pyramid, thus making the corner a horn, as one moves away from the apex in the corner? Application, say one wanted to design a sealed, bass reflex, or horn loaded low frequency cabinet to go into that corner so that it’s Fc, matched that of the corner’s intrinsic Fc, thus allowing the walls leading away from the cabinet to be a well-matched horn extension of the cabinet placed there. What is that Fc? With a flare rate so quickly opening it must be something like around 100-300Hz, but do you know how to calculate a corner’s natural Fc precisely? I realize it won’t be ideally exponential, probably closer to conical, thanks for your time and response!