Simon Lewis Posted January 17, 2014 Share Posted January 17, 2014 The maths is useful, but bear in mind that depending upon the room's critical distance, drop off due to the inverse square law gets swamped by the level of the reverberant sound field. In fact, loudspeaker directivity and the room's critical distance will play a significant part in determining intelligibility, If all that's needed is a bit of music and youtube playback, it may not matter too much. If speech intelligibility is important, then speaker location, aiming, directivity, level and (tailored) frequency response are important. Furthermore, the acoustic environment will have a significant effect. Whereas multiple Control 1s can do the job, they tend to spray sound everywhere, so work best when placed close to the listener and aren't turned up so much that all can hear each speaker. A more directional speaker used in a distributed format may perform better, Link to comment Share on other sites More sharing options...
paulears Posted January 17, 2014 Share Posted January 17, 2014 Who mentioned d&b? Nice idea but perhaps a mismatched brand and location. The German link gives no idea of the price, neither does Google, so while nice to look at, they don't seem to have any dealers, and therefore how can we tell? Link to comment Share on other sites More sharing options...
Electrolytic Posted January 17, 2014 Share Posted January 17, 2014 With a pair of speakers several meters in the air and a pair down below, I don't think mismatched speakers is going to be critical factor.He mentions replacing his 'crappy disco speakers', a suggestion was put forward.You have to ring them for a quote. Link to comment Share on other sites More sharing options...
paulears Posted January 17, 2014 Share Posted January 17, 2014 Don't you know how much they are then? You recommended them, so are we talking £300 a box or what? Seems a bit odd to suggest an unknown make and not know the details. Have you got some? Don't be shy - you don't seem to have any link with the company, so what made you suggest them as an alternative to d&b? Link to comment Share on other sites More sharing options...
azlan Posted January 17, 2014 Share Posted January 17, 2014 The maths is useful, but bear in mind that depending upon the room's critical distance, drop off due to the inverse square law gets swamped by the level of the reverberant sound field. In fact, loudspeaker directivity and the room's critical distance will play a significant part in determining intelligibility, If all that's needed is a bit of music and youtube playback, it may not matter too much. If speech intelligibility is important, then speaker location, aiming, directivity, level and (tailored) frequency response are important. Furthermore, the acoustic environment will have a significant effect. I completely agree, the reason I focused on that bit of maths was two-fold, firstly, it was because the OP mentioned that he was worried about the difference in levels between the front and back of the room with a single pair of speakers, and secondly, I had it all fresh in my mind, as I had basically given that presentation to one of my colleagues a couple of days ago, whilst explaining why we deployed a system the way we did (6 speakers flown from a truss instead of on stands dotted around the room as per usual) and why it meant we didn't have or need the usual pair at the back of the room. assuming that the school hall is a fairly typical, reverberant nightmare of a room, the key to getting intelligibility will most likely be simply trying to keep as much sound off the walls as is practical, and if possible, some strategic acoustic treatment (even a few small panels of foam roughly where the sound from the speakers first hits the walls would potentially cause a marked improvement) with regards to dispersion, if the op is looking at flying speakers, he could use trigonometry to fairly easily calculate the required vertical dispersion, or both the vertical and horizontal could be approximated by using a scale plan and a protractor, with the aim being to find the best compromise between covering the required seating area, whilst not excessively interacting with the walls (the floor should not pose too many problems once the seats are occupied) we should ask as well, does the OP have suitable flying points/existing scaff or truss that he can fly off (and indeed has a competent person to perform the installation), and is the budget likely to be sufficient to purchase flyware as well as loudspeakers (it could be as simple as forged shoulder eyebolts and SWR, or it could be a dedicated steel structure depending on the chosen speakers), and indeed get to know a little bit more about the existing signal chain (and EQ's, system controllers etc.. that may be in use) and what the budget for the upgrade is Link to comment Share on other sites More sharing options...
Electrolytic Posted January 18, 2014 Share Posted January 18, 2014 so what made you suggest them as an alternative to d&b? a man on a get out throughly recommended them the other night that is all... he wan't even a sound man... ... ... Link to comment Share on other sites More sharing options...
Bobbsy Posted January 18, 2014 Share Posted January 18, 2014 The maths is useful, but bear in mind that depending upon the room's critical distance, drop off due to the inverse square law gets swamped by the level of the reverberant sound field. In fact, loudspeaker directivity and the room's critical distance will play a significant part in determining intelligibility, If all that's needed is a bit of music and youtube playback, it may not matter too much. If speech intelligibility is important, then speaker location, aiming, directivity, level and (tailored) frequency response are important. Furthermore, the acoustic environment will have a significant effect. Whereas multiple Control 1s can do the job, they tend to spray sound everywhere, so work best when placed close to the listener and aren't turned up so much that all can hear each speaker. A more directional speaker used in a distributed format may perform better, You're totally right, of course... ...but, given the choice I'd still go with one speaker each side, as high as possible, and angled down and inwards to point at the audience to use the human bodies as a form of acoustic treatment to keep as much sound as possible off the walls. Obviously I'd also prefer speakers with a known (and suitable) dispersion pattern for the same reason. Multiple Control 1s, even with delays, just add to the potential problems. Frankly, even with all the known problems and limitations, a bit of thought will make it better than 90% of the school halls I've had the misfortune of being in. Link to comment Share on other sites More sharing options...
haymere Posted January 18, 2014 Share Posted January 18, 2014 Having worked as a school installer, I would suggest a manufacturer like Brooke make good boxes with good mounting options at reasonable cost. Brooke INH10 I work for a company called VME based in knutsford if you need a supplier or fitting, just ask for Mark Polden. VME Link to comment Share on other sites More sharing options...
Brian Posted January 18, 2014 Share Posted January 18, 2014 ... a manufacturer like Brooke make good boxes with good mounting options at reasonable cost. And yet, like many manufacturers, they completely fail to mention what the dispersion pattern of their cabinets is. Link to comment Share on other sites More sharing options...
Bobbsy Posted January 18, 2014 Share Posted January 18, 2014 ... a manufacturer like Brooke make good boxes with good mounting options at reasonable cost. And yet, like many manufacturers, they completely fail to mention what the dispersion pattern of their cabinets is. ...and the spec is somewhat deficient in other areas too. For example a "+1dB/-3dB (or whatever) spec after the frequency response, half space or full space, that sort of thing. Link to comment Share on other sites More sharing options...
sleah Posted January 18, 2014 Author Share Posted January 18, 2014 I really seemed to have started something! Reverberation isn't a big problem in this hall. Curtains floor to ceiling down one side and curtains at the top third with notice boards below along the other side.Modern false ceiling with tiles coming almost half-way down the back wall with notice boards below.The only mass of exposed concreate is the stage end :) Sound quality wise, I've already said the existing kit is OK for our needs. They are 12" Skytec plastic cabs, which are only just up the food chain from SkyLab!! I'm now looking at a pair of 12" Behringer Eurolive passives in White. Power handling slighty more than the current cabs, mounting brakets are cheap and in white too.Cheap as chips, just over £120 inc VAT each! And let's face it, YouTube clips will sound no better through a D&B rig than the above mentioned Behringers. (If you compare like for like cabs). Why would I spend more on 'better' known kit, bespoke or customised etc when even I probably won't notice any difference let alone the average teacher?When it matters, for musicals or concerts I'll be bringing in better kit anyway. Link to comment Share on other sites More sharing options...
the kid Posted January 18, 2014 Share Posted January 18, 2014 What is the hight ? We installed a system much like in shops with zoning in our cafe for student radio and staff training days, If I remember right about 15x25x4m distributed with 15 speakers in the roof. It worked very well for speaking and we could take out zones as required. Link to comment Share on other sites More sharing options...
timsabre Posted January 18, 2014 Share Posted January 18, 2014 Another issue with any sort of distributed speaker system, when used for speech, is that it takes away the focus from the guy up at the front who is speaking as the sound no longer seems to be coming from them. Obviously this is not relevant for background music or announcements... Depends what you're doing with it. Link to comment Share on other sites More sharing options...
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