I originally posted this idea in the DBLH thread here (http://www.diyaudio.com/forums/full-range/236335-dblh-2.html#post3506867)which was for a Double Back Loaded Horn wall-mount speaker. This is clearly a different animal as it is not wall mounted and has many more pipes. Below is a repeat of original post to kick things off.
The speaker is sort of a conventional 'Scoop Bucket' type BLH in appearance. However, the cabinet is divided (top to bottom) into 5 separate horns, each tuned to a different frequency, and each fed by a common "throat" plenum connected to a driver chamber. The speaker is designed from scratch by individually optimizing the lengths, throats, mouths, and chamber volume to produce a relatively flat response that has deep bass extension, with each horn resonance peak offset from its neighboring horn resonance peaks.
Here is the simulation using AkAbak of a 5 horn BLH with the horns front facing and stacked next to each other at the bottom of the cabinet. I have not worked out the full physical dimensions of the cabinet and what it would take to fold and route the passages yet. I am assuming the cabinet will be 25 in wide to accommodate qnty 5 x 5 in wide horns. The longest horn is 144 inches and each successive one is multiplied by 0.9, 0.8, 0.7, and 0.6 factors. Horns mouth 1 (longest) will be 12 in tall x 5 in wide, the rest are all 8 in high x 5 in wide. The throats for each horn were optimized and ended up as 2 in, 0.7 in, 0.7 in, 1.0 in, 0.7 in (times width of channel of 5 in). A common throat leading from driver chamber to plenum manifold of multiple throats is 4.0 in to 5.0 in x 5.0 in long (times width of channel of 5 in). The driver chamber is 18 liters. The driver is the W5-1611, and all calcs were for 1 watt input measured at 1 meter away. The first plot shows the horn output for 1, 2, and 3. The second plot is for horn output 3, 4, and 5. The third plot shows the total output of all horns combined with driver direct radiation (black, red is longest horn, green is shortest horn). As you can see, there are lots of resonance peaks for each horn but the spacing is evenly spread out as expected and the amplitudes are pretty well balanced. I imagine that with damping added to the driver chamber, and maybe a little in the common plenum section these peaks will all be blended into one smooth output. The fourth plot is the impedance, fifth plot is the driver cone displacement, and sixth is impulse response.
Any feedback on this design from folks would be appreciated. Is this just too much trouble to get a smooth horn output? I think the advantage will be that the sound from this speaker will have all the benefits of immediacy in deep bass response (the impulse response is relatively quick compared to a bass reflex or MLTL that will have significant delay). So the sound should be more natural. The 30 Hz bass extension is quite impressive with controlled cone motion just at the limit of the driver's range.
This is response from horns 1(longest) to 3:
This is response from horns 3 to 5 (shortest):
This is the combined response including driver direct radiation (black) and longest (red) and shortest (green) horns:
This is the impedance:
This is the driver cone displacement:
And if you are interested in building this and don't want to yet spend $50 in a TB W5-1611 driver, very good results can also be obtained with a budget Monacor SP50X driver ($20 at MCM http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-SP-50X-/55-4636) as shown below (thanks to @Ryani for pointing me in this direction). I will provide detailed build plans shortly. Foam core seems to be the way to go for test build and if you like it - go with wood.
Let me know if you are interested in a build and I will try to draw up plans soon.
Here is the freq response with the SP50X (no changes to cabinet):
The speaker is sort of a conventional 'Scoop Bucket' type BLH in appearance. However, the cabinet is divided (top to bottom) into 5 separate horns, each tuned to a different frequency, and each fed by a common "throat" plenum connected to a driver chamber. The speaker is designed from scratch by individually optimizing the lengths, throats, mouths, and chamber volume to produce a relatively flat response that has deep bass extension, with each horn resonance peak offset from its neighboring horn resonance peaks.
Here is the simulation using AkAbak of a 5 horn BLH with the horns front facing and stacked next to each other at the bottom of the cabinet. I have not worked out the full physical dimensions of the cabinet and what it would take to fold and route the passages yet. I am assuming the cabinet will be 25 in wide to accommodate qnty 5 x 5 in wide horns. The longest horn is 144 inches and each successive one is multiplied by 0.9, 0.8, 0.7, and 0.6 factors. Horns mouth 1 (longest) will be 12 in tall x 5 in wide, the rest are all 8 in high x 5 in wide. The throats for each horn were optimized and ended up as 2 in, 0.7 in, 0.7 in, 1.0 in, 0.7 in (times width of channel of 5 in). A common throat leading from driver chamber to plenum manifold of multiple throats is 4.0 in to 5.0 in x 5.0 in long (times width of channel of 5 in). The driver chamber is 18 liters. The driver is the W5-1611, and all calcs were for 1 watt input measured at 1 meter away. The first plot shows the horn output for 1, 2, and 3. The second plot is for horn output 3, 4, and 5. The third plot shows the total output of all horns combined with driver direct radiation (black, red is longest horn, green is shortest horn). As you can see, there are lots of resonance peaks for each horn but the spacing is evenly spread out as expected and the amplitudes are pretty well balanced. I imagine that with damping added to the driver chamber, and maybe a little in the common plenum section these peaks will all be blended into one smooth output. The fourth plot is the impedance, fifth plot is the driver cone displacement, and sixth is impulse response.
Any feedback on this design from folks would be appreciated. Is this just too much trouble to get a smooth horn output? I think the advantage will be that the sound from this speaker will have all the benefits of immediacy in deep bass response (the impulse response is relatively quick compared to a bass reflex or MLTL that will have significant delay). So the sound should be more natural. The 30 Hz bass extension is quite impressive with controlled cone motion just at the limit of the driver's range.
This is response from horns 1(longest) to 3:
This is response from horns 3 to 5 (shortest):
This is the combined response including driver direct radiation (black) and longest (red) and shortest (green) horns:
This is the impedance:
This is the driver cone displacement:
And if you are interested in building this and don't want to yet spend $50 in a TB W5-1611 driver, very good results can also be obtained with a budget Monacor SP50X driver ($20 at MCM http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-SP-50X-/55-4636) as shown below (thanks to @Ryani for pointing me in this direction). I will provide detailed build plans shortly. Foam core seems to be the way to go for test build and if you like it - go with wood.
Let me know if you are interested in a build and I will try to draw up plans soon.
Here is the freq response with the SP50X (no changes to cabinet):
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Oh gosh, I will have to look that up when I get home. I'm leaving the office soon. They are still playing in the livingroom but they don't sound as good as the spirals I don't think. Loud? OMG yes but I think that's mostly due to the drivers not the cab.
As far as the name goes, I will stick with the original if that's ok. I like the name Penthorn.
Pentahorn on the other hand is almost as good. You keep that one.
I don't want to crowd this thread I just wanted to poke my nose in and say hi.
As far as the name goes, I will stick with the original if that's ok. I like the name Penthorn.
Pentahorn on the other hand is almost as good. You keep that one.
I don't want to crowd this thread I just wanted to poke my nose in and say hi.
Cal,
Penthorn, Penthouse, what's the difference... Not crowding at all - you are welcome to poke around and add all you want. I think Panpipe may be closer to what this is because of how the horns are all next to each other in a stack like a Peruvian panpipe. I guess it would look more like it if the mouths went out the top. I need some time to draw this up.
Penthorn, Penthouse, what's the difference... Not crowding at all - you are welcome to poke around and add all you want.
I think Panpipe may be closer to what this is because of how the horns are all next to each other in a stack like a Peruvian panpipe. I guess it would look more like it if the mouths went out the top. I need some time to draw this up.
I am working on to-scale rough sketches. The drawings will be sufficient for someone suitably enthusiastic about building it if they were up to estimating dimensions of some internal parts and pieces from the drawings using the scale grid. CAD drawings will take time that I don't have right now. Are you guys interested in the simple scale drawing?
Sketch of Panpipe BLH for W5-1611
Here is a scale drawing that should get you guys started. The design is not "sexy" or cool because it was meant for easy construction and transfer to wood construction. A fancy curved version with exposed manifolds and tubes like a V8 dragster header pipes will look cool but hard to make. Maybe in strict FC it can be done...
Anyhow, here is the design drawing. Each square on plan is 2x2 inches. The perspective drawing is not to scale but to give a sense of how things fit together. I made all the horn mouths 12 in to make it look better and easier to build. The performance is still good and excessive bass can always be reduced by adding stuffing to the offending pipe. This design shows the basic plan for all 5 horns laid on a common drawing. Each successive shorter pipe length is reduced at first by contracting the folded path right out of the plenum. Three different lengths for horns (1), (2), and (3) are accomplished by moving the turn corner up. For horns (4) and (5), the up-pipe connects directly to the plenum at the top. Simultaneously, the turn right before the final 90 deg turn out to the world has to be moved down as the horn gets shorter. The numbering of the associated movements of the divider corner above the mouth and the fold below the plenum are numbered to match. As you construct this, it will be helpful to use a piece of string measured out to the distances indicated to do a final check of the paths lengths before gluing in the final corner fold pieces. It is not a big deal to be off by an inch or two so there is slack in the construction when it comes to lengths.
I would build the 5 horns separately by laying the channel walls on each separate divider panel. Then glue the 5 panels together with PVA and a clamp or weight. Then glue the plenum box on top of the 5 horn sections.
Put stuffing in the main driver chamber (adjustable through driver cutout) and add loose stuffing in the plenum chamber (~3 ozs teased out to be fill box). You may want to tie a string to the wad of stuffing in the plenum to enable easy extraction through driver chamber if needed.
Good luck and have fun!
Oh, forgot to mention... all dimensions in inches.
Here is a scale drawing that should get you guys started. The design is not "sexy" or cool because it was meant for easy construction and transfer to wood construction. A fancy curved version with exposed manifolds and tubes like a V8 dragster header pipes will look cool but hard to make. Maybe in strict FC it can be done...
Anyhow, here is the design drawing. Each square on plan is 2x2 inches. The perspective drawing is not to scale but to give a sense of how things fit together. I made all the horn mouths 12 in to make it look better and easier to build. The performance is still good and excessive bass can always be reduced by adding stuffing to the offending pipe. This design shows the basic plan for all 5 horns laid on a common drawing. Each successive shorter pipe length is reduced at first by contracting the folded path right out of the plenum. Three different lengths for horns (1), (2), and (3) are accomplished by moving the turn corner up. For horns (4) and (5), the up-pipe connects directly to the plenum at the top. Simultaneously, the turn right before the final 90 deg turn out to the world has to be moved down as the horn gets shorter. The numbering of the associated movements of the divider corner above the mouth and the fold below the plenum are numbered to match. As you construct this, it will be helpful to use a piece of string measured out to the distances indicated to do a final check of the paths lengths before gluing in the final corner fold pieces. It is not a big deal to be off by an inch or two so there is slack in the construction when it comes to lengths.
I would build the 5 horns separately by laying the channel walls on each separate divider panel. Then glue the 5 panels together with PVA and a clamp or weight. Then glue the plenum box on top of the 5 horn sections.
Put stuffing in the main driver chamber (adjustable through driver cutout) and add loose stuffing in the plenum chamber (~3 ozs teased out to be fill box). You may want to tie a string to the wad of stuffing in the plenum to enable easy extraction through driver chamber if needed.
Good luck and have fun!
Oh, forgot to mention... all dimensions in inches.
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My head hurt more from writing code for this from the top of my head without putting it on paper first.
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