Members agedhorse Posted January 8, 2007 Members Share Posted January 8, 2007 The "below the normalized frequency of the array" is an important factor which I take as to the effect of actively increasing the baffle loading on the device. The sensitivity increase is not across the entire band, but the portion of the driver's low freq. response that is rolling off. Then there is also the change off the dispersion pattern due to the dipole effect at some frequencies. Boseengineer is on top of this stuff better than anyone here... comments??? The EAW numbers do not include the effects of power compression, they are purely simulation or theoretically extrapolated numbers. Typoical power compression between 1 watt (small signal model) and full power are in the range of 4-6 dB... not insignificant and if you must meed a maximum SPL performance specification must be included in the calculations. Link to comment Share on other sites More sharing options...
Members cheebs Posted January 8, 2007 Author Members Share Posted January 8, 2007 i am a studio and live sound tech. and am very good with my hands. i've build some very good sub box for cars both wood and fiberglass. much better than what i could have paid for. now i wanted to build some small tops to be used with some subs for dj and small sound gig use. see my thinking in starting this was what i could build for 200 or 300 dollars had to be better than what i could buy for the same. i felt better wood drivers and crossover. had to be that much better than pyle gem sound gemeni and just a little better than behringer, samson and low end yamaha. was i wrong in thinking that? you guys have put me on to some really good info. some forums were to snobish to give me any info. kind if you don't know this or that we can't help you. some just had no clue. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 8, 2007 Members Share Posted January 8, 2007 As somebody who designs commercial speaker products, I think you may find it hard to build something that's as good and as cheap as some very respectable products out there. You might give a look at Peavey, Cerwin Vega (ProStax line), Yorkville, Yamaha, and JBL 500 series as something that you can also listen to and determine before you build their suitability for your needs. Doesn't mean you can't build a good speaker for a competative cost but it's not as easy as one would imagine. Link to comment Share on other sites More sharing options...
Members cheebs Posted January 8, 2007 Author Members Share Posted January 8, 2007 Originally posted by agedhorse As somebody who designs commercial speaker products, I think you may find it hard to build something that's as good and as cheap as some very respectable products out there. You might give a look at Peavey, Cerwin Vega (ProStax line), Yorkville, Yamaha, and JBL 500 series as something that you can also listen to and determine before you build their suitability for your needs.Doesn't mean you can't build a good speaker for a competative cost but it's not as easy as one would imagine. easy is not part of this conversation or it would have lasted two posts. the problem i have is almost all the speakers you are talking about push pass the price point i was talking about. of course i don't think am up to the task of building a speaker to equal those you brought up. and if i had 350 to 500$ per cabinet to spend we wouldn't be talking. the prostax 12 is 341$ at that cost for two i could just buy a matrix 1000. it has an amp two tops and sub 750$. it is a good system but it' s all and one. i feel it can be outgrown too quickly. and from what i have picked here and over the last few weeks their specs are not as good as stated. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted January 9, 2007 Members Share Posted January 9, 2007 Originally posted by bazza54 The actual theory describes two identical devices radiating side by side. In practice, if you connect a loudspeaker to an amplifier and turn it up until it dissipates 1W then plug another loudspeaker into the same amp with the volume at the same setting, each loudspeaker dissipates 1W. 1W + 1W = 2W. Most PA amplifiers are rated for 4ohm loads so using 2 drive units (most of which are 8ohm) whether in one or two cabinets means more power. Of course there is nothing stopping you adding the extra loudspeaker and then turning the level down so there is still 1W total or so it is no louder than with one loudspeaker.Some bright engineering type will probably chime in and tell us how the extra load of the second loudspeaker causes a voltage drop so you don Link to comment Share on other sites More sharing options...
Members bazza54 Posted January 9, 2007 Members Share Posted January 9, 2007 What I was arguing was that if you are trying to compare efficiency ratings, you have to be consistent. It doesn't matter if one cab is lower impedance than the other(whicjh would probably allow your power amp to put out more power at the lower impedance) What matters is that if you want an accurate efficiency comparison, you put 1 watt into each unit and measure it at 1 meter. (you could use other variables buth they both need to be the same. I Link to comment Share on other sites More sharing options...
Members tlbonehead Posted January 9, 2007 Members Share Posted January 9, 2007 Originally posted by bazza54 I Link to comment Share on other sites More sharing options...
Members cheebs Posted January 9, 2007 Author Members Share Posted January 9, 2007 Originally posted by tlbonehead The only reason UI am bothered with it is because that was evidently the poster's initial reason for going with dual small woofer. And they didn't seem to understand what it was. That's all. yes and no while i don't really understand the technical behind what we are talking about. i do understand the idea. but thats why i didn't understand how two speakers could be no different than one. again i'm not tring to reinvent a eaw or jbl just a better plye, gemeni or samson. Link to comment Share on other sites More sharing options...
Members bazza54 Posted January 9, 2007 Members Share Posted January 9, 2007 The only reason UI am bothered with it is because that was evidently the poster's initial reason for going with dual small woofer. And they didn't seem to understand what it was. That's all. Efficiency wasn Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 9, 2007 Members Share Posted January 9, 2007 (With respect to the LF driver) Your argument about "coupling" is primarily noticed at lower frequencies because the driver piston couples with a better match to the air. This results in a slightly extended LF -3dB point. As the frequency increases, this coupling effect diminishes but another effect, a modification of the dispersion pattern) occurs causing localized increases in SPL, and this effect also diminishes as the frequency continues to rise but then another effect (beaming) starts to occur. So the polar pattern is governed by a lot of variables. Comparing efficiency to directional sensitivity, there are a lot of possible gains available due to pattern control... this is why a 16 box Vertec hang is (or seems) so "effficient". The sensitivity is increased due to the significant inprovement in forward directionality, but the actual efficiency does not really increase as the sound is just being better and more useably concentrated. Something to ponder... if doubling the # of speakers for the same nominal input power would always result in a 3dB increase, why would this not continue to increase for each doubling of drivers? (Hint... it doesn't) This is why your "argument" (in a philosophical sense, not attitude) does not hold up in generality. The reason for using a larger HF driver is to allow better (for some designs) sharing of power bandwidth, and to improve directionality at lower transition frequencies. This may not really be important for lower level speaker systems but as you start looking at real performance gains, it does become a valuable design tool. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted January 9, 2007 Members Share Posted January 9, 2007 Originally posted by bazza54 Efficiency wasn Link to comment Share on other sites More sharing options...
Members cheebs Posted January 9, 2007 Author Members Share Posted January 9, 2007 Originally posted by tlbonehead Efficiency was the wrong term or idea for what the OP was getting at. whats "op"? Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 9, 2007 Members Share Posted January 9, 2007 Originally posted by cheebs whats "op"? original poster Link to comment Share on other sites More sharing options...
Members bazza54 Posted January 10, 2007 Members Share Posted January 10, 2007 (With respect to the LF driver) Your argument about "coupling" is primarily noticed at lower frequencies because the driver piston couples with a better match to the air. This results in a slightly extended LF -3dB point. As the frequency increases, this coupling effect diminishes but another effect, a modification of the dispersion pattern) occurs causing localized increases in SPL, and this effect also diminishes as the frequency continues to rise but then another effect (beaming) starts to occur. So the polar pattern is governed by a lot of variables. Adding extra drivers will extend the low frequency response and change the polar pattern, so will changing the cone size, the magnet strength and the stiffness of the suspension. None of that means that what I have stated is incorrect. There seems little point in discussing this further, and while you may be determined to ridicule my comments, I fail to see why you dispute the references I gave to back up what I said. Are you saying that both Meyer and Panasonic are employing people who do not understand what they are doing and that their published work is incorrect? Providing references to work which has been previously published, has been peer reviewed and considered accepted knowledge is standard practice in academic papers. It may be beneficial to your argument to provide references which back up your claim that doubling the number of drive units does not give a theoretical 6dB increase in level. Comparing efficiency to directional sensitivity, there are a lot of possible gains available due to pattern control... this is why a 16 box Vertec hang is (or seems) so "effficient". The sensitivity is increased due to the significant inprovement in forward directionality, but the actual efficiency does not really increase as the sound is just being better and more useably concentrated. May be you should re-read what I wrote. In the horn example I gave I stated that increasing directionality of a speaker/horn/array doesn Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 10, 2007 Members Share Posted January 10, 2007 bazza54 First of all I am NOT ridiculing any of your comments. I don't see where you are getting this from. You were initially generalizing from some papers that doubling the number of drivers will increase the SPL by 3dB without accepting (or looking to create an argument for argument's sake) overall information without considering the details within the topic of the paper. I don't understand your approach here? Doubling the number of drivers with the same total power doesn't add 3dB to the efficiency across the speaker's entire bandwidth. In fact it affects primarily the lowest octave, the same as increasing the cone area would. It may also affect the polar sensitivity some but this may be good or bad depending on the approach and the goals. You initially suggested that doubling the power to the speakers added 3dB and doubling the power added 3dB. I just pointed out that there are many ways to add power without doubling the number of drivers. JBL drivers are ava9ilable in a G version which is 4 ohm nominal and used for this very purpose. As far as the 2" driver example, there are many ways to impliment a stupid design. I was pointing out why 2" drivers have their place and some of the criteria used in selecting a large format device. There are negative trade-offs as well. If you are looking for a fight, forget it. There are folks here who want to learn about this stuff and providing accurate info is important to them, sans the attitude. Link to comment Share on other sites More sharing options...
Members cheebs Posted January 10, 2007 Author Members Share Posted January 10, 2007 nobodies fighting this is GROWN FOLK TALK! hey guys i'm sorry my questions started this i was only tring to understand some things. i have learned from both of you. the reason for this is mine so you guys shouldn't debate so hard. the way i asked my questions were not clear enough. i don't know if you get it or not you guys are saying close to the same thing. agedhorse you are telling that the 8s are cool but a 10 or 12 would be easier to do. i still think i can do it just not first. sometimes when we lissen to someone talk about something and it doesn't sound like they know what their talking about it makes it hard to figure out how to explain a subjet to them. the reason i kept asking was it was sounding like you don't understand so you can't do. try this i'll be easier for you. but i do get you guys. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 10, 2007 Members Share Posted January 10, 2007 One of the primary reasons why a "2 small driver" pro speaker is desireable is for low profile applications where you need the additional piston area but also need the low profile for under balcony and stage lip front fills. This is the thrust of (pretty much) all of the pro 2 driver speaker offerings, and most use 6" or 6.5" drivers to keep the package as slim as possible. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted January 11, 2007 Members Share Posted January 11, 2007 nobodies fighting this is GROWN FOLK TALK! hey guys i'm sorry my questions started this i was only tring to understand some things. i have learned from both of you. the reason for this is mine so you guys shouldn't debate so hard. the way i asked my questions were not clear enough. i don't know if you get it or not you guys are saying close to the same thing. agedhorse you are telling that the 8s are cool but a 10 or 12 would be easier to do. i still think i can do it just not first. sometimes when we lissen to someone talk about something and it doesn't sound like they know what their talking about it makes it hard to figure out how to explain a subjet to them. the reason i kept asking was it was sounding like you don't understand so you can't do. try this i'll be easier for you. but i do get you guys.Well, I certainly wasn't trying to keep you from doing it. I was just trying to get you to understand that some of your reasoning for wanting to do so was flawed. Link to comment Share on other sites More sharing options...
Members cheebs Posted January 11, 2007 Author Members Share Posted January 11, 2007 Well, I certainly wasn't trying to keep you from doing it. I was just trying to get you to understand that some of your reasoning for wanting to do so was flawed. see how things can get mixed up. my reasons for doing it were not mixed up they are clear. a small lightweight pa box better than those cheap dj boxes. but my reasoning of how it should work was. my comment was more to agedhorse. and im not saying that was the intent just how it came across. Link to comment Share on other sites More sharing options...
Members bazza54 Posted January 11, 2007 Members Share Posted January 11, 2007 If you are looking for a fight, forget it. There are folks here who want to learn about this stuff and providing accurate info is important to them, sans the attitude. If not taking your word on faith as absolute gospel is picking a fight then I guess that is what I am doing. While it may be a rarity for your views to be questioned here, it is hardly an uncommon practice elsewhere to ask for further evidence over and above Link to comment Share on other sites More sharing options...
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