psy Posted March 2, 2009 Share Posted March 2, 2009 as some of you will know im currently looking around for new gear and am basically looking for a set up that consists of 2 bins and 2 tops. I always thought the tops would be 12" speakers but most of the packages I find online or in my local music shop tend to have 15" tops. does it make a difference? also with regards to the bins is there a difference between 15" and 18" I would have imagined the 18 would have produced better low end but I have noticed from a few companies who make both that whilst their 18's are dearer they can actually be rated less in power consumption. which would be better between say a 15" 250wrms bin or an 18" 200wrms bin from the same manufacturer as the 18's do seem to be dearer. oh and I usually look at the rms value of a speaker but some only have program or peak whats the difference between rms and program? cheers in advance Link to comment Share on other sites More sharing options...
drsound Posted March 2, 2009 Share Posted March 2, 2009 Generally, a larger speaker will have a lower frequency "window" in which it operates effectively. A gross generalisation but basically true. A very simplistic view would be as follows (there are, as always, many examples that counter this explanation): 12" vs 15" tops - a 12" driver has a lower moving mass and is therefore more likely to give smooth detailed response on things like vocals and acoustic guitar. A 15" driver will be able to sustain acceptable sound pressure levels at lower frequencies and might well have a higher overall SPL but perhaps at the expense of fine detail. A 15" box will be better able to produce full-range music without a sub. 15" vs 18" subs - a 15" sub will be less able to produce ground shaking bass than an 18" unit but conversely it will be able to work higher up the frequency scale at the top end and take the LF load off your tops. Bear in mind that very few instruments produce natural sounds down in the 20 - 40 Hz region so if you're not heavy on synthesised music (or pipe organs and those giant alpine horn thingies) it's not essential to go this low. Power rating is not the whole story - there's no point in rehashing a topic I know has been covered before so have a search for "speaker sensitivity". If you're interested in making as much noise as possible then the maximum SPL is the figure to look at. This is complicated by different manufcaturers using different standards of course but it should be a directly comparable figure within the same product range. RMS (or more correctly "continuous" or "average") power is the theoretical maximum sine wave power that could be shoved into the driver for hours on end without it melting. Programme power is a measure of the maximum short term power that the driver will handle without expiring and is more reflective of real music than a sine wave. Again this has been covered in some detail before, ask uncle Google. As a broad rule you would select your amplifier size to be more than the RMS power to allow it to fully exploit the peak power handling of the driver. Link to comment Share on other sites More sharing options...
psy Posted March 2, 2009 Author Share Posted March 2, 2009 Generally, a larger speaker will have a lower frequency "window" in which it operates effectively. A gross generalisation but basically true. A very simplistic view would be as follows (there are, as always, many examples that counter this explanation): 12" vs 15" tops - a 12" driver has a lower moving mass and is therefore more likely to give smooth detailed response on things like vocals and acoustic guitar. A 15" driver will be able to sustain acceptable sound pressure levels at lower frequencies and might well have a higher overall SPL but perhaps at the expense of fine detail. A 15" box will be better able to produce full-range music without a sub. 15" vs 18" subs - a 15" sub will be less able to produce ground shaking bass than an 18" unit but conversely it will be able to work higher up the frequency scale at the top end and take the LF load off your tops. Bear in mind that very few instruments produce natural sounds down in the 20 - 40 Hz region so if you're not heavy on synthesised music (or pipe organs and those giant alpine horn thingies) it's not essential to go this low. Power rating is not the whole story - there's no point in rehashing a topic I know has been covered before so have a search for "speaker sensitivity". If you're interested in making as much noise as possible then the maximum SPL is the figure to look at. This is complicated by different manufcaturers using different standards of course but it should be a directly comparable figure within the same product range. RMS (or more correctly "continuous" or "average") power is the theoretical maximum sine wave power that could be shoved into the driver for hours on end without it melting. Programme power is a measure of the maximum short term power that the driver will handle without expiring and is more reflective of real music than a sine wave. Again this has been covered in some detail before, ask uncle Google. As a broad rule you would select your amplifier size to be more than the RMS power to allow it to fully exploit the peak power handling of the driver. thats a great help and detailed enough to get me on the right path to finding out more myself thanks m8 Link to comment Share on other sites More sharing options...
Killyp Posted March 2, 2009 Share Posted March 2, 2009 RE the subwoofers, anything with a 15" or 18" cone should really have a 4" voice coil. Power handling is all well and good, but if the coil has a limited number of turns and (as is usually the case with 3" voice coil designs) the magnet isn't particularly powerful, those 1000 watts will end up feeling quite a bit more feeble than you would expect. Link to comment Share on other sites More sharing options...
drsound Posted March 3, 2009 Share Posted March 3, 2009 Which will be reflected in the sensitivity. The efficiency of conversion from electrical to kinetic energy is a function of both the fixed magnetic field and the electrical field strength generated by the voice coil. The larger each of these values, in general the more acoustic output (ignoring back emf and saturation etc). Best method though? Buy what sounds right to you within your budget. Much easier than Thiele-Small. Link to comment Share on other sites More sharing options...
Doug Siddons Posted March 3, 2009 Share Posted March 3, 2009 I find that on this type of rig ie 2tops and 2 subs the best combination is 2 x12" for tops and 1x15" and 1x18" for the bottom end gives the best sound.The 15 giving the "kick" and 18" adding the warmth/body. These I would stack as a "point source" and would assume they are all from the same manufacturer and appropriate crossovers ect are used. Just my 2p worth Link to comment Share on other sites More sharing options...
Rob_Beech Posted March 6, 2009 Share Posted March 6, 2009 Add a 6.5 high mid driver and horn load the 15 and you have pretty much the best of everything. Link to comment Share on other sites More sharing options...
Jivemaster Posted March 6, 2009 Share Posted March 6, 2009 There is a trade-off between sound style, price, and no two people will entirely agree. I went to a DJ speaker meet a while ago and of all the names and systems demonstrated by FAR my favoured sound came from an odd rig! Full range sent out to a Mackie 1501 bin, hi-pass outs (at line level) sent back to the rack to a Bose processor and an amp then back out to a pair of Bose 802. Out of all the offerings from brand names that was the ONLY system that coped well with several styles of DJ likely music AND responded well to microphone announcements. However the sound you want and can sell regularly is the sound you need to find. Link to comment Share on other sites More sharing options...
Sound In Gloucestershire Posted March 6, 2009 Share Posted March 6, 2009 depends what you mean by brandnames? Skytec Warrior and Peavey are all brandnames, but doesnt mean you have made a whole of market comparison (or even broken the surface) Link to comment Share on other sites More sharing options...
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