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  • Diy 2 way 15 inch pa speakers

    Hello, i have build some sturdy high end 2 way boxes similar to jbl srx 715 cabinets. But my drivers are in need of an upgrade. I am looking at some high power eminence pro series la15850 drivers , crossover at 1.2khz/12db octave into a jbl 2445j mounted on an eminence h2ea horn. Would this setup work as i have found a good local deal on the jbl drivers. Mostly used for dj sets and occasional live music , these are also being accompanied by 2 dual 18 wharefdale pro 2400 watt subs to handle the lows.

  • #2
    What drivers are you upgrading from? Those drivers certainly are capable and that is the proper way to do a 15" 2-way, but when the crossover is that low I'd like to see a steeper slope to protect the compression driver, it would see significant signal levels down below horn loading frequencies when played at war volumes which can sound harsh at the very least or could cause damage worst case. Is biamping an option?
    Paul O

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    • #3
      The hf is an eminence asd 1001 or something like that just a little baby driver and the lf i have no clue as they have no data on them anywhere.. All i know is that they are 300 watt eminence drivers. And hiw steep of slope would you think would be best 18? And well i already have 3 ep4000's 1 per sub and 1 was for my tops , but would like to upgrade the 1 ep as its on the low side of power for this build, but would not be running full for the first bit anyway so im kinda trying to uss the bi amp as my last option if possible

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      • #4
        I like 4th order crossovers for this, I have B&C DE750s actively crossed at 1khz with a DCX and they sound great.. no sign of strain at all even at high SPLs. Those 2445s are a little bigger again so they may be fine but then they are also known for sounding aggressive and the crossover may have something to do with that.
        Paul O

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        • #5
          When you're using subs to handle the lows there's usually nothing to be gained in using fifteens in the mains, other than excess size and weight. I say usually, as you can design a top loaded with a fifteen that optimizes results above 80Hz. The SRX 715 doesn't do that, so your cabs are probably a lot larger than they need to be.. Also, while the LA15850 is a pretty good driver it's specs are best for a cab that does go well below 80Hz. I suggest you do some driver/cab modeling along the lines of maximizing results above 80Hz while minimizing the cab size and weight. Depending on how your present cabs are constructed you may be able to reduce their size considerably.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #6
            Originally posted by billfitzmaurice View Post
            When you're using subs to handle the lows there's usually nothing to be gained in using fifteens in the mains, other than excess size and weight. I say usually, as you can design a top loaded with a fifteen that optimizes results above 80Hz. The SRX 715 doesn't do that, so your cabs are probably a lot larger than they need to be.. Also, while the LA15850 is a pretty good driver it's specs are best for a cab that does go well below 80Hz. I suggest you do some driver/cab modeling along the lines of maximizing results above 80Hz while minimizing the cab size and weight. Depending on how your present cabs are constructed you may be able to reduce their size considerably.
            I 2nd this. We did a demo with some Community Sonus 3 way speakers and the 15s compared to the 12s didn't sound as good to my ears, but also when we were running the sub-woofers with them, there was nothing gained as Bill has already mentioned.
            "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

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            • #7
              I'm going to somewhat disagree with the "no need for 15s" notion, IMO it's relative to how much sub is being used and the type of program material. I agree with the idea when it comes to DJs, most of the rigs I setup are 12+1 tops over single 18 subs, I sometimes use 15 tops because that is what's available and I don't hear any difference so for this type of use the rule applies. But for live bands the rules change for me, with keys and guitar there is more energy in the low mids and 15s do a better job even when high passed at 80hz.
              Paul O

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              • #8
                Thanks for the responce, well im not quite looking at redoing my cabinets as its been a lot of work putting them together and the wood is not cheap and i have had custom grills made as well that were not cheap so that why i was just trying to figure out what would work good with the cabinet i have. If the la15850 isint the best suited driver , what would work good with thise same jbl 2445's thats in the same price range roughly , and roughly same power as the eminence , any thoughts.

                l

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                • #9
                  Originally posted by Paul O View Post
                  I'm going to somewhat disagree with the "no need for 15s" notion, IMO it's relative to how much sub is being used and the type of program material. I agree with the idea when it comes to DJs, most of the rigs I setup are 12+1 tops over single 18 subs, I sometimes use 15 tops because that is what's available and I don't hear any difference so for this type of use the rule applies. But for live bands the rules change for me, with keys and guitar there is more energy in the low mids and 15s do a better job even when high passed at 80hz.
                  Paul -- I suppose what i meant was that when running those particular speakers, I found that the 12s were much clearer. That was probably in just how they were voiced. All things being equal was Bill has pointed out before, speaker size doesn't determine tonal quality. Where I am coming from (with the Community speakers as the sole example) is that the sensitivity between the 12s and 15s were almost identical, but the 15s had a lower frequency response. I believe the mid-range x-over frequency was the same between the cabs, but if I crossed the 12" 3-way at 90-110Hz and crossed the 15" 3-way at 90-110Hz, "I" wasn't gaining anything.

                  I can see your point though. I was just using a specific example. IMO I really don't prefer 2 way PA speakers that utilize a 15" woofer. I don't feel as though they can ever get the horn to cross low enough to get the balance correct in the x-over. The coloration is weird. the 12" seems to work better in that regard. Just my $0.02
                  "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

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                  • #10
                    Originally posted by Diycanada View Post
                    Thanks for the responce, well im not quite looking at redoing my cabinets as its been a lot of work putting them together and the wood is not cheap and i have had custom grills made as well that were not cheap so that why i was just trying to figure out what would work good with the cabinet i have. If the la15850 isint the best suited driver , what would work good with thise same jbl 2445's thats in the same price range roughly , and roughly same power as the eminence , any thoughts.

                    l
                    Can you tell me a little bit about your cabinet? Volume, dimensions, port style, etc? Right off the bat, my knee jerk reaction is that there could be a better 15" driver. Also what are you using for the crossover that is predetermined at 1.2KHz? The H2EA horn is a 2" throat correct? What is the min x-over frequency of the CD you have? My apologies for not looking it up.
                    "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

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                    • #11
                      The cabinets are basically pretty close to the srx 715 cabinets, there a little diferent on the one side as i made it so i can lay it down . so as for box volume i have no clue as to how to figure it out as it is an irregular shape so i was kinda just estimating something similar to the jbl's. Correct it is a 2 inch and the jbl2445's lowest xover freq is 500hz at 100watts aes vs xover at 1000hz+ is 150 watts aes.

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                      • #12
                        Lay it down as in a monitor is what i meant not that i would be using it for that purpose but just for the sake of having it i did.

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                        • #13
                          Originally posted by Diycanada View Post
                          The cabinets are basically pretty close to the srx 715 cabinets, there a little diferent on the one side as i made it so i can lay it down . so as for box volume i have no clue as to how to figure it out as it is an irregular shape so i was kinda just estimating something similar to the jbl's. Correct it is a 2 inch and the jbl2445's lowest xover freq is 500hz at 100watts aes vs xover at 1000hz+ is 150 watts aes.
                          If you give me the dimensions I can help you out. Without knowing the box volume or port tuning (is it tuned already?), its really difficult for 'me' to give you any solid advice.
                          "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

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                          • #14
                            Originally posted by STIchris722 View Post
                            Where I am coming from (with the Community speakers as the sole example) is that the sensitivity between the 12s and 15s were almost identical, but the 15s had a lower frequency response. I believe the mid-range x-over frequency was the same between the cabs, but if I crossed the 12" 3-way at 90-110Hz and crossed the 15" 3-way at 90-110Hz, "I" wasn't gaining anything.
                            Yes, I find the same thing with my 12+1 and 15+1 powered speakers, there really is no point to using the larger box when they are high passed over subs.

                            Originally posted by STIchris722 View Post
                            IMO I really don't prefer 2 way PA speakers that utilize a 15" woofer. I don't feel as though they can ever get the horn to cross low enough to get the balance correct in the x-over. The coloration is weird. the 12" seems to work better in that regard.
                            Agreed, most 15+1 speakers I have ever heard could be described this way but the Yamaha DRX15s would be an exception. The designers have done a remarkable job with the processing in these and they really are one of the best sounding PA speakers on the market today. I don't think it would be possible to replicate this performance with a passive box using the same drivers, which means of course that the advanced processing utilized here is the secret sauce that make this all possible.

                            But I do have passive speakers with 15" drivers that IMO sound even better than the Yamahas. The difference is they also have 2" exit compression drivers on waveguides (not compression throat horns which can add their own coloration/distortion) and the boxes are biamped and actively processed with DSP.
                            I had previously used these same 15" drivers in passive 3-way boxes and became very aware of how bad a 15 can behave at higher frequencies.. these things made all kinds of noises when allowed to operate up into cone breakup frequencies. It's common knowledge outside guitar amp uses that you never allow a 15 to run fullrange and with a full 3-way crossover I avoided that problem with those boxes.
                            But it is remarkable what can be accomplished when you can see response anomalies with a measurement system and correct it with DSP processing, I found some bumps and humps in the response of these drivers at lower frequencies and correcting that removed some of the flaws in their sound that I had always struggled with, the end result is this combination of drivers and processing produces exceptional performance.
                            So yeah it is possible to make a good sounding 15" 2-way PA speaker but it's not easy or cheap, in this case I have $1500 in drivers and another $1500 in the rack that powers and processes them.
                            Paul O

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