Folded Horn Speaker Design Software
Some time back, on one of the speaker / DIY internet forums, someone described their method of folding bass horns as 'drawing the straight profile of the horn on a piece of paper,cutting it out and cutting it into a number of segments, and gluing a piece of string along the centre line'. The string keeps the centre of each segment aligned whilst folding the horn around. I cannot remember who suggested this, nor what forum it was, so if it was you then with details and I can credit you with the idea. This method makes sense, although in reality is not entirely accurate as the accoustic centre of a bend is towards the outside of the bend.
I want to design a large basshorn. It will be a folded horn to go into the back of a car, rear seats are going and the car is a large estate (I think.
However, using the physical centre line results in only a slightly longer accoustic horn length, causing no degradation in performance. The following describes the way in which I implemented the above idea using the power of AutoCAD. Undoubtedly, other Cad software may be used provided it can run a command script file. Whilst manipulating 3D segments in AutoCAD is straightforward, generating the initial profile is a difficult task made easier with the use of a Microsoft Excel spreadsheet downloadable. Please note that this spreadsheet only calculates single hypex type flares in metric millimetres. The first page of this spreadsheet contains instructions on its use. As noted in the spreadsheet instructions, AutoCAD should be set up for millimetres before running the script.
After the spreadsheet output has been pasted to file horn.scr and saved, the script can be run from within AutoCAD by selecting Tools - Run Script and selecting horn.scr as shown below. Here it can be seen that although there is a extra bend, the folding is still quite mild and still plenty of room.
Also shown here is another handy feature of AutoCAD. The green area is a closed polyline representing the rear chamber area of the speaker. The properties of this polyline gives us the actual area, and from that we can estimate the rear chamber volume. In this case, the volume is pretty much exactly what is required. However, the area below the baffle, either side of the throat section, is still wasted space. By not allowing the baffle plate to seal off this area, it can be included in the rear chamber volume. Again, using the undo, I will reduce the cabinet depth a fraction more at the front, resulting in the fold below.
Here the total of green areas is the desired rear chamber volume, meaning the only wasted space in the whole cabinet is the three corners (although these can be utilised for electronics such as internal power amplifiers, processors etc). In the case of this example, the speaker is a 10' model, cabinet height is 900mm, depth is 770mm and width is 400mm. This will form the basis for a future compact pro sound sub capable of extension to 40Hz.
All that is left to do now is to surround this path with pieces of wood, using standard AutoCAD techniques, and then removing the path (sounds simple, but is still quite involved - but highly accurate).
This is my new folded horn design. I needed feed back to see if I need to change anything. I am about half way on 2 of the cabinets. I got two eminence 18's on the way now. To put in them.
Each one will stand about 4 feet high. I got the dimensions out in the shop. I can get them to someone if they need them.
Right now I have 2 Peavey black widows in single peavey cabinets and I am looking for more bass. The two fifthteen do ok on kick drum and mids but just enough for tonal bass. Hopefully this works great. I had priced some new cabinets but they just cost to much compared to what it would cost to build them for.
I can build and load 3 of these with 18's for the price of one of those cerwin vegas. So do you all think it is a good design? I used google sketchup to make the blue print designs the best I could. At the top where the access panel for the woofer it will be double ply of 3/4' MDF. Every thing glued and screwed and I'll coat the whole cabinet with armor plate. Originally Posted by Brad Horstkotte Did you use hornresp or similar to model the horn?
The horn path length appears far too short to work well as a subwoofer, maybe half what it should be. Where folded horns are concerned the best results come from using as small a driver as has sufficient Vd for the application in as large a horn as packspace will allow, not as large a driver as will fit into as small a cabinet as possible. The Cerwin Vega folded horns are fine examples of how a folded horn sub should not be built.
And assuming that these are intended for portable pro-sound use you do not want to build them from MDF; well braced 1/2' BB plywood is far stronger but much lighter. If you shrink the driver, the horn effectively becomes larger. When you re-design, consider that fact and that a quality 12' is a better driver size for something like this. At 12' you will get more performance for your money, a good 18' costs much more. I hate to say it but the Eminence 18's are going to sound muddy in your application. I owned one of these: which use Eminence 18's. It never lived up to it's specs, for the exact same reason your design is likely to be compromised.
Shrink the driver, or be prepared to build a horn that takes up half a room. Originally Posted by Tom Bley On Bills THT builds I could clearly see and follow the horn path and see it getting larger toward the mouth of the horn but, I can't tell hide nor hair from your sketch or model of what's going on, sorry. I guess I have the same question as Brad. Maybe I should go grab another cup of coffee. I'm just here to observe & learn. Do you have a link for bills design.
I'm new here. I have bulit alot of subwoofer cabinets for cars, but loud speaker design is a art.
Front Loaded Folded Horn Speaker Design
I would love to build a awesome cabinet, I could make some money where stay dealing with loud speakers. Everyone down here wants folded horns. Originally Posted by imagic If you go to Guitar Center you can see the so-called folded horns that serve as inspiration. They are not good designs, to say the least - Not so much a horn as a cheap hybrid of T-line, bandpass and pseudo-waveguide.
The real goal is to create as loud a mid-bass boom as possible for the least $$$. The confusion comes from the fact that they are marketed as folded horns. T That is the horn that my friend has that made me want one. He has a QSC 2450 pushing bought of them.
His love gogo music for parties and it does the kick drum from the music great from two of them. This will be mostly for smooth jazz, new rap(which has the bass drop), gogo like chuck brown, pure pleasure, new diemsions,etc ( alot of kick drum). I have heard the EV folded horns and the older carvin ones before they came out with the dual 18 T cabinets. With the genre of music I listen two the cerwin vegas did the best over all, for the size of the cabinet. Right now I am using some black widow 15's but they just don't do it anymore.
When I stepped up from my Nikko 130 amp(real good amp for being older) to the two crown powerbase 2's. Have you checked this out? Edit - from the description: The LA400 defies conventional wisdom, which states that an 18' woofer is required to drive a bass horn. 18' woofers simply do not have the rigidity required to drive the high acoustic impedance present in a horn throat.
As a result, traditional 18' bass bins get loud, but only produce one note very well. The LA400 in contrast uses a proprietary heavy duty 12' woofer. The woofer has the motor structure of a traditional 18' device, and its cone is reinforced to be a better engine for compact horn-loading. This woofer is then loaded onto a properly designed bass horn which matches path length to cone area and maximizes driver efficiency.
The result is tight, punchy sub bass response that not only will shake your foundation, but is articulate and musical as well. That's what we're talking about here, they are actually selling it. Copy that design.
Back Loaded Folded Horn Speaker Design
Originally Posted by mtyler7807 This will be mostly for smooth jazz, new rap(which has the bass drop), gogo like chuck brown, pure pleasure, new diemsions,etc ( alot of kick drum). I have heard the EV folded horns and the older carvin ones before they came out with the dual 18 T cabinets.
With the genre of music I listen two the cerwin vegas did the best over all, for the size of the cabinet. Right now I am using some black widow 15's but they just don't do it anymore. When I stepped up from my Nikko 130 amp(real good amp for being older) to the two crown powerbase 2's.