So, long story short I have a very big workshop (~600m^2) to fill with sound. I realise that nothing I do will be 'hi-fi', however I am trying to do the best I can with a limited budget. The speakers can be mounted from ground level to 6m above the floor, either against a wall low or in open space high - I realise this is far, far from ideal and unfortunately both groups of speakers need to be on the same side of the workshop. I have roughly 400w RMS/channel to play with and an amplifier stable to 4 ohms. Listening distance will be roughly between 10-20m (~20-60') away from the speakers.
Originally I was going to get 4x12" PA drivers, however I'm yet to find anything half decent second hand. What I do have - lots of Seas P17RC/P drivers. I've used these in 2 way enclosures both ported and sealed, with sound quality being fairly decent but anything below 80Hz sucking in a sealed arrangement.
Originally the plan was just to bang a heap of these in a large sealed box and go nuts, however I then started looking into comb filtering and the effects of multiple drivers - clearly, my 2xMMTMM/side plan (idiots logic: 4x6.5" drivers having roughly the same size cone area as 1x12") wouldn't work as effectively as I had hoped. I then came across Bessel arrays (having read, but not properly understood) every paper and patent on them that I could find as well as the few threads on here. Despite that, I didn't find much information on people who had practically implemented it.
Now - would this work? I could run two 'channels' of Bessel arrays evenly divided down the workshop length. If I was to use 6 drivers and the middle space taken up by a tweeter, this would give me a listening distance of approximately 12-14m away, depending on how closely I mounted the drivers together.
Now, assuming this would work, is it possible to port the Bessel array? BBP6 (where I first came across the term) seems to suggest no, but it will let me model it anyway. I realise low frequency response is never going to be amazing in a place that big with smaller drivers.
Failing that, any suggestions? I don't mind doing crazy woodwork and I can put a heap of time into this - however as it's somebody elses money I don't have a huge budget to play with.
Thanks guys!
Originally I was going to get 4x12" PA drivers, however I'm yet to find anything half decent second hand. What I do have - lots of Seas P17RC/P drivers. I've used these in 2 way enclosures both ported and sealed, with sound quality being fairly decent but anything below 80Hz sucking in a sealed arrangement.
Originally the plan was just to bang a heap of these in a large sealed box and go nuts, however I then started looking into comb filtering and the effects of multiple drivers - clearly, my 2xMMTMM/side plan (idiots logic: 4x6.5" drivers having roughly the same size cone area as 1x12") wouldn't work as effectively as I had hoped. I then came across Bessel arrays (having read, but not properly understood) every paper and patent on them that I could find as well as the few threads on here. Despite that, I didn't find much information on people who had practically implemented it.
Now - would this work? I could run two 'channels' of Bessel arrays evenly divided down the workshop length. If I was to use 6 drivers and the middle space taken up by a tweeter, this would give me a listening distance of approximately 12-14m away, depending on how closely I mounted the drivers together.
Now, assuming this would work, is it possible to port the Bessel array? BBP6 (where I first came across the term) seems to suggest no, but it will let me model it anyway. I realise low frequency response is never going to be amazing in a place that big with smaller drivers.
Failing that, any suggestions? I don't mind doing crazy woodwork and I can put a heap of time into this - however as it's somebody elses money I don't have a huge budget to play with.
Thanks guys!
The ceilings are around 25m high - unfortunately we'd have to hire a crane to ceiling mount anything. The 6m height is a block of offices inside the building which I can easily get on top of
It's a gym, with low member numbers (only 10-15 people in there at a time). Just background to slightly above conversation levels would be good. The floor is mostly covered with equipment, however most is low to the ground (platforms 5cm heigh, to racks 2m high but mostly empty space)
Hi dreadnoughtstrength,
Yes it would work and you can Port the Drivers but you should also consider to add one or two Subs below the Array(s) if SPL below ~100 Hz turns out to be too weak.
See the Picture for Seas P17RC/P Ported Box calc:
Attachments
IIRC the thing with Bessel arrays is that they sound best at a distance... just like bagpipes 
12-14m might be about right; I'd definitely port them, but add some polyswitches to protect the speakers at those after-work parties....
(& perhaps a passive line level HPF just below the box tuning freq?)
12-14m might be about right; I'd definitely port them, but add some polyswitches to protect the speakers at those after-work parties....
(& perhaps a passive line level HPF just below the box tuning freq?)
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IIRC the thing with Bessel arrays is that they sound best at a distance... just like bagpipes
12-14m might be about right; I'd definitely port them, but add some polyswitches to protect the speakers at those after-work parties....
(& perhaps a passive line level HPF just below the box tuning freq?)
I've played around a bit with these speakers as a sub - I built a Decware Wicked One out of some scrap with two drivers and it actually sounds great down to 45Hz. Not massive output, but no audible distortion. Below that and you can start to hear the cones flapping around so I think we're exceeding xmax. I actually built a couple of active subsonic filters for another project set at 40Hz that I can put in this signal chain pretty easily - thanks for the input.
The issue I'm having now is working out how I'm going to wire it for any sort of decent load. With a 7 driver array (6 speakers), I'm looking at 1.8ohms in the 'standard' wiring guise. With 9 (7), this is down to 1.1 ohm - definitely too low. I could series run these for 36 or 44 ohms - not ideal. I noticed the amplifier can run bridged mono at 8 ohms, but I have no idea about what sort of power output I will get (there's next to no information about bridged mono output on my amplifier, Crown XLS402, aside from the fact it can do bridged mono at 4 ohms).
Suggestions?
My French isn't any good but the following link may be of use to you:
Bessel arrays
Hope you can use it...
Bessel arrays
Hope you can use it...
I went out and measured things yesterday - turns out there's a bit less area than I thought. Probably makes things easier.
The issue is for the 6 or 7 speaker array, 4 or 6 have to be given equal power and 2 need to receive half power. I've only seen 4 in parallel + 2 in series, or 4 in series + 2 in parallel.
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