No tweeter.. The driver is full-range and has a strongly elevated treble region (which should offset its use as a "walsh" driver). You might need a shelving network however to "flatten-out" the response, but it really depends on how the driver behaves when listened to inverted as a radial driver (..or "walsh" style).
The driver can handle 32 watts continuous, 64 peak. That amounts to 15db of gain from the 90 db average of the driver, or 105 at 1 meter (108 peak). This isn't it's *linear* range, but an increase in harmonic distortion shouldn't be a problem for your intended use. The amplifier could have 1000 watts at 8 ohms; the only real requirement is that it has 64 watts for the 5 to 6 ohms (nominal) of the driver.
The 12" Beyma has an EBP (Fs/Qe) of 70. In my simulations the 12" B&C fullrange and the 8 Ohm Ciare with an EBP of 160/150 were already a bit too weak. One could try a larger cross-section with these drivers, but then the size becomes unmanagable.
From the specs (if one can trust those at the Lowther website) the Lowther PM2C would be OK, but 1) ridiculously expensive an 2) maybe too low displacement to deliver enough bass.
From the specs (if one can trust those at the Lowther website) the Lowther PM2C would be OK, but 1) ridiculously expensive an 2) maybe too low displacement to deliver enough bass.
I had very natural results (even more natural than with the reflector cone) with a similar driver (Ciare HX201) facing the ceiling without any correction. The treble rise is compensated by the reflection loss. But from theory with a delay higher than 20 ms the ceiling reflection is perceived as an echo and the two frequency responses are no longer combined. The direct sound is perceived as lacking treble then. Could be a problem in large auditoriums. The HX201 is capable of delivering 8-9 dB more SPL than the Visaton. In theory it works in a reasonably sized BR enclosure, but people were not so happy with it (displacement?). It became popular in Germany as driver in a really large and heavy horn (facing the listener and corrected).
If you mount the driver inverted what you get is more a midwoofer than a fullrange driver.
To clarify, this was mounted in a standard fashion, in the enclosure, rather than with exposed sides (like a reverse Walsh)?
Thanks, everyone, for the further thoughts.
I wish I knew more, and I also wish I had more resources available so that I could experiment at will.
The main designs proffered appear to be:
1) Full-range pointed up, with or without diffuser
2) Full-range pointed down, like a Walsh driver
The main question is, given limited resources, which design has the greatest chance to succeed in this application?
To summarize and clarify:
I am seeking similar output capability as my current keyboard amp, which is rated at 2x50W, going into 2 Eminence Alpha 8s (125W RMS / 250W music) and 2 80W 3.5x3.5 horns.
I am considering using as an amplifier something like this: 41Hz Audio:AMP10-BASIC kit which is rated at 2x60W at 8 ohms.
This will be most often used it small to medium-sized rooms and performance spaces. For large spaces I would just use a house PA.
Omni-directionality, frequency response around 60-18000Hz, relatively low cost, ease of construction, and being lightweight are other primary concerns. Thanks again for all suggestions; I'm sorry I do not know more, and I appreciate as much detail as you can provide.
(As we now seem to be talking full-range, mods, please feel free to move this thread).
I wish I knew more, and I also wish I had more resources available so that I could experiment at will.
The main designs proffered appear to be:
1) Full-range pointed up, with or without diffuser
2) Full-range pointed down, like a Walsh driver
The main question is, given limited resources, which design has the greatest chance to succeed in this application?
To summarize and clarify:
I am seeking similar output capability as my current keyboard amp, which is rated at 2x50W, going into 2 Eminence Alpha 8s (125W RMS / 250W music) and 2 80W 3.5x3.5 horns.
I am considering using as an amplifier something like this: 41Hz Audio:AMP10-BASIC kit which is rated at 2x60W at 8 ohms.
This will be most often used it small to medium-sized rooms and performance spaces. For large spaces I would just use a house PA.
Omni-directionality, frequency response around 60-18000Hz, relatively low cost, ease of construction, and being lightweight are other primary concerns. Thanks again for all suggestions; I'm sorry I do not know more, and I appreciate as much detail as you can provide.
(As we now seem to be talking full-range, mods, please feel free to move this thread).
Maybe something like this? Solid Acoustics dodecahedron speakers Should solve the low spl problem of fullrangers, since you will use 12 
Standard mounting, driver on ear-height, facing the ceiling, no reflector, sealed enclosure, TQWT, later very large open back enclosure together with a 15" bass driver.
I just see the Tangband W8-1772 is much cheaper in the US than over here.
Parts-Express.com:Tang Band W8-1772B 8" Neodymium Full Range Driver | Tang Band W8-1772 8" Full Range Driver full range tb speakers neodymium driver line array point source midrange home theater computer speaker center channel set tube amplifier
It has a strongly rising frequency response, good for ceiling flooding. Displacement is more than usual for a fullrange driver, and with an enclosure size of merely 40 l a BR should do the 60 Hz. Port dimensions would be 4" diameter, 5" length. I took the measurement data of the K+T magazine, where the Qts is a bit higher than the value published by the manufacturer. Sensitivity is comparable with the Alpha-8 and two of these enclosures are still quite small. It has 60 W max, not RMS, but if your music has dynamics and you don't use the amps to fight loudness wars this should be OK.
Parts-Express.com:Tang Band W8-1772B 8" Neodymium Full Range Driver | Tang Band W8-1772 8" Full Range Driver full range tb speakers neodymium driver line array point source midrange home theater computer speaker center channel set tube amplifier
It has a strongly rising frequency response, good for ceiling flooding. Displacement is more than usual for a fullrange driver, and with an enclosure size of merely 40 l a BR should do the 60 Hz. Port dimensions would be 4" diameter, 5" length. I took the measurement data of the K+T magazine, where the Qts is a bit higher than the value published by the manufacturer. Sensitivity is comparable with the Alpha-8 and two of these enclosures are still quite small. It has 60 W max, not RMS, but if your music has dynamics and you don't use the amps to fight loudness wars this should be OK.
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Interestingly (if I'm understanding you correctly), that's actually along the same lines but more extreme than the keyboard amp I'm using (Motion Sound)
Though in the amp it's a pseudo-stereo effect the efficacy of which is partially dependent upon one's position in relation to the amp.
This is similar in concept to the hemispherical speaker unit I posted earlier. At this point perhaps I should mention that I have one of those hemispherical speakers buried in a closet.Maybe something like this? Solid Acoustics dodecahedron speakers Should solve the low spl problem of fullrangers, since you will use 12
Maybe I should give it another try. As I recall it uses 6 Polk 5-1/4" car audio coaxial speakers in a serial/parallel configuration.The neodymium magnet should help keep the weight down, and an enclosure of that size in Baltic birch should be around 10 lbs. Add in a pound or two for the amp and it's a lightweight and portable solution. And you think it would work well without a diffuser? Thanks again.
From the frequency response I am quite sure it works without a diffusor, given that you stay below the 20 ms for the ceiling reflection. Also sounds strange in the absolute near field (distance to the listener < half the distance to the ceiling. If you try with a diffuser you need a partially absorptive one to get the treble down. For the HX201 I tried a 90° paper cone filled with mounting foam and it worked.
Why not do something like the classic Leslie organ speakers, maybe without the rotating effect though? Leslies may well be the worst sounding speakers you'll ever hear, but they do distribute the sound all over the room. They have a large woofer pointing downwards into a smaller cabinet that have vents on all sides. Below 1 kHz they are more or less omni because of this. On the top there is single driver with a double horn, pointing in opposite directions. You could use two horn tweeters and achieve kind of the same thing.
I've got a Leslie sitting in my living room and I have to say that firstly the woofer does point downwards but into a short rotating scoop with a 90deg bend in it and secondly one half of the 'double horn' is a dummy (ie it is blocked off), it is merely there to balance the rotating mass.
Btw Leslies are beautiful sounding speakers if used with an organ or electric guitar. They are an effect, not a speaker for accurate reproduction by any stretch of the imagination and have virtually no output above 6kHz. Mine does however has got a very nice sounding 45w mono valve amp in it.
Btw Leslies are beautiful sounding speakers if used with an organ or electric guitar. They are an effect, not a speaker for accurate reproduction by any stretch of the imagination and have virtually no output above 6kHz. Mine does however has got a very nice sounding 45w mono valve amp in it.
True, there is only one "active" tweeter horn on the Leslie (my mistake..), but when the horn rotates it spreads the sound all over the room, and thats the point. Without any rotation the speaker will not do that, so two (or more) horns should be better I think. When the Leslie bass rotor is off, the woofer is more of less omni.
Leslies sounds great with an organ of course, my favourite is the Hammond A100.... simply beautilful.
Leslies sounds great with an organ of course, my favourite is the Hammond A100.... simply beautilful.
on the cheap at Ebay there's a wideband Sammi 8" with whizzer 390109337367 - - its reference efficiency is about 2.2%, it has a 2" coil and is ~$20 sans shipping - there's not a lot of high frequencies above 5KHz but might be sufficient. I would think smaller voice coil fullrange could fry fast and compress - I burnt a WBAL with 25 watts by going out of a room and the cd changer moved from a wide dynamic cd.
here's the Sammi in a klam - it had another 6-8db to go http://www.youtube.com/watch?v=znfE7hjQ40o
here's the Sammi in a klam - it had another 6-8db to go http://www.youtube.com/watch?v=znfE7hjQ40o
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Just reread this thread in a search for info on the Beyma 12GA50>In addition to all this driver talk, the OP wants a lightweight solution; perhaps this diy composite cabinet type is a nice option to meet that requirement.
Foam core/plexiglass+carbon shell. For those with stiffness/resonance doubts about this method, it's the same composite method with which an airplane can be built.
I think it's a stunning cabinet construction option.
An externally hosted image should be here but it was not working when we last tested it.
Foam core/plexiglass+carbon shell. For those with stiffness/resonance doubts about this method, it's the same composite method with which an airplane can be built.
I think it's a stunning cabinet construction option.
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