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Post by hulkss on Dec 5, 2023 20:35:27 GMT -5
A forum member asked for information about my main front loudspeakers in the photo below. Yes, they are a uniquely designed pro-audio line array.  The PreSonus CDL12P can operate over a ground plane without suffering from destructive floor-bounce effects that plague normal speakers. The curved line array of 16 tweeters (2 cabinets) extends all the way down to the floor to take advantage of the ground-plane acoustic reflection. The floor provides a reflective surface boundary that acoustically extends the array below floor level, creating a virtual four cabinet array that is six feet tall. This controls vertical coverage and directivity to well below the 420 Hz crossover point. Ceiling reflections are greatly reduced as compared to a typical box style system. The system can be played extremely loud and remains very clean and effortless at all levels. The large number of drivers minimizes distortion. Driven with two internal 500 watt amplifiers per cabinet, the system can generate very-high peak levels. I've attached two documents with more technical information. There is a ton of info on Don Keele's site (see download link at top of linked page). Here is a photo with a mirror that helps visualize how the floor doubles the size of the array. Light and sound both reflect from the floor in similar fashion.  This photo has the grill cut away on one side revealing the drivers.  |
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Post by PaulBe on Dec 6, 2023 10:55:07 GMT -5
A forum member asked for information about my main front loudspeakers in the photo below. Yes, they are a uniquely designed pro-audio line array. The PreSonus CDL12P can operate over a ground plane without suffering from destructive floor-bounce effects that plague normal speakers. The curved line array of 16 tweeters (2 cabinets) extends all the way down to the floor to take advantage of the ground-plane acoustic reflection. The floor provides a reflective surface boundary that acoustically extends the array below floor level, creating a virtual four cabinet array that is six feet tall. This controls vertical coverage and directivity to well below the 420 Hz crossover point. Ceiling reflections are greatly reduced as compared to a typical box style system. The system can be played extremely loud and remains very clean and effortless at all levels. The large number of drivers minimizes distortion. Driven with two internal 500 watt amplifiers per cabinet, the system can generate very-high peak levels. I've attached two documents with more technical information. There is a ton of info on Don Keele's site (see download link at top of linked page). Here is a photo with a mirror that helps visualize how the floor doubles the size of the array. Light and sound both reflect from the floor in similar fashion. This photo has the grill cut away on one side revealing the drivers. This is a unique application of line array modules. I was wondering how you got such flat phase in the treble range. The system appears to be cardioid. Is the 2" driver line open back? Your implementation is CBT- like with the floor reflection. How do you carry through CBT behavior with the linear array modules? Do you modify the driver connections or lower the level on the upper module? It's been a while since I looked at Don Keele's site. I like what JBL has done with CBT: jblpro.com/product_families/cbt-series-passive-controlled-coverage-columnsI recall seeing one HT with the JBL CBT series. It was a YouTube video. |
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Post by 405x5 on Dec 6, 2023 12:12:26 GMT -5
A forum member asked for information about my main front loudspeakers in the photo below. Yes, they are a uniquely designed pro-audio line array. The PreSonus CDL12P can operate over a ground plane without suffering from destructive floor-bounce effects that plague normal speakers. The curved line array of 16 tweeters (2 cabinets) extends all the way down to the floor to take advantage of the ground-plane acoustic reflection. The floor provides a reflective surface boundary that acoustically extends the array below floor level, creating a virtual four cabinet array that is six feet tall. This controls vertical coverage and directivity to well below the 420 Hz crossover point. Ceiling reflections are greatly reduced as compared to a typical box style system. The system can be played extremely loud and remains very clean and effortless at all levels. The large number of drivers minimizes distortion. Driven with two internal 500 watt amplifiers per cabinet, the system can generate very-high peak levels. I've attached two documents with more technical information. There is a ton of info on Don Keele's site (see download link at top of linked page). Here is a photo with a mirror that helps visualize how the floor doubles the size of the array. Light and sound both reflect from the floor in similar fashion. This photo has the grill cut away on one side revealing the drivers. I want to take some time and study those PDFs you put out there sounds interesting. All of this reminds me of the dearly departed Roy, Allison, and his papers and studies on room, boundaries and their effect on loudspeaker designs. Many different cabinets shapes, and driver placements uniquely came out of all of that work. |
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Post by hulkss on Dec 6, 2023 13:45:47 GMT -5
The central 2" driver line is closed back. The 12" mid-bass drivers have vented cabinets, however, I crossover to the subwoofer before the vents come into play. I run the top box at -3 dB relative to the bottom box. When I ordered these speakers without hearing them, I was expecting that I would have to modify them in some way. I was really surprised at how great they sound. They are totally stock except for some peel & stick felt pads on the bottoms. My home theater is known as "the concert simulator". A 152" acoustically transparent video screen lowers in between the Right and Left speakers. The image starts at the floor. It gives the impression that you can walk right onto the show stage. An even better experience than I was hoping for! Here's a pic of the developers and a tech paper (attached) about the prototype of this loudspeaker.  Attachments:17-10-18 Design.pdf (1.58 MB)
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Post by PaulBe on Dec 6, 2023 14:43:17 GMT -5
The central 2" driver line is closed back. The 12" mid-bass drivers have vented cabinets, however, I crossover to the subwoofer before the vents come into play. I run the top box at -3 dB relative to the bottom box. When I ordered these speakers without hearing them, I was expecting that I would have to modify them in some way. I was really surprised at how great they sound. They are totally stock except for some peel & stick felt pads on the bottoms. My home theater is known as "the concert simulator". A 152" acoustically transparent video screen lowers in between the Right and Left speakers. The image starts at the floor. It gives the impression that you can walk right onto the show stage. An even better experience than I was hoping for! Here's a pic of the developers and a tech paper (attached) about the prototype of this loudspeaker. Ha! Don Keele strikes again. In a surprisingly affordable package. Great use of his speaker. Your HT setup is one of the most fun looking and intelligent setups I've seen. Thanks for the Paper. Thanks so much for sharing your HT. |
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Post by hulkss on Dec 6, 2023 15:04:04 GMT -5
Thanks for the compliment. I hope that seeing this system can inspire some others (using an Emotiva Processor of course!). |
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Post by webmst007 on Feb 19, 2024 0:50:14 GMT -5
I love the CBT gear and continue a long-standing correspondence with Don we started some years ago - he is just such a pleasure to know. His son is active in a CBT Facebook Group if anyone is interested. www.facebook.com/groups/149436383798694/?mibextid=uJjRxrThey have all of Don's papers online there. Now if I could just get up off my lazy **** and get on with it I could actually build the CBT array we've spoken about :-) |
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