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I am contemplating a very-high-sensitivity direct-radiator project, and am asking for suggestions for drivers. I am looking for one driver that covers frequencies from "as low as possible" to approximately 250 Hz, and another driver that covers frequencies from approximately 250 Hz to approximately 1500 Hz. I am considering ONLY closed-box enclosures with Qtc=0.707, because I like the associated sound quality. I am not interested in vented-box or other enclosure types.
For the "up to 250 Hz" driver, I have found that the classic tradeoff between F3, enclosure volume, and sensitivity is rather well represented. For example (all numbers from WinISD and/or Hornresp, as appropriate), a Ciare PW455 offers 99dB@2.83V (8 Ohm driver) in a 2Pi infinite baffle, and an enclosure volume of only 36 liters for Qtc=0.707, but F3 is a very high 113 Hz. By contrast, an Eminence Kilomax Pro 18A offers a nice low F3 of 50 Hz, but only 96dB@2.83V and it requires a huge 270 liter enclosure. I think that the best compromise that I have found is the Eminence Omega Pro-18A: 60 Hz / 133 liters / 97dB@2.83V (8 Ohm) or the Eminence Omega Pro-18C: 60 Hz / 126 liters / 97dB@2V (4 Ohm). I have examined most of the current B&C, Ciare, Eminence, EV, GPA, JBL, and RCF lines, but would appreciate suggestions for other candidates.
For the "250 Hz - 1500 Hz" driver, I have looked at 8", 10", and 12" drivers, and among those that I have considered four stand out;
B&C 12PE32: 206 Hz / 7.7 liters / 100dB@2.83V,
EV EVM-12L: 173 Hz / 10.8 liters / 99dB@2.83V,
B&C 12MH32: 204 Hz / 5.4 liters / 99dB@2.83V,
RCF L12P100K, 245 Hz / 3.9 liters / 99dB@2.83V.
Since I have four NOS EVM-12L sitting in boxes in my basement my decision has probably already been made, but still I would appreciate suggestions for other candidates.
Thank you,
Greg
Follow Ups:
Perhaps you should state your ultimate sonic goals and how the speaker system will be used ( home, PA ). What size room, budget etc. What drivers are you looking at to use above 1500hz ?
Home use, fairly large room -- 500 sq ft, music (no infrasonics, and low bass will be supplied by a separate subwoofer), no specific limits on the budget but not looking for anything exotic. The system will be triamplified.
For the HF I have a couple of Alnico Altec 288 that I think I'll mate to Faital LTH142.
Thanks.
That is a nice sized room !!! The Altec 288's are very good drivers for midrange duty. Since you already have 4 EV 12l's that is a good place to start. I would use 2 per side sealed to get 90hz-100hz and run them up to 500hz where the 288's take over.
You could use the Faital horn but I would go to DIY Soundgroup site and get a 300hz tractrix horn. They have thicker material and I think will sound better. For the tweeter I would use a Fostex 900 series horn tweeter unless your budget is big enough to get the T500Amk2's ( Madisound )which is one of the best tweeters on the planet. You could use a simple 6db crossover between midrange and tweeter and tri-amp the midrange on down.
Just for information, give John Inlows site a look. There is some good info on horns and subwoofers. Good luck.
The EVM12L will only go down to 173 Hz in a sealed box. And they have an anomaly in their frequency response right around 2500 Hz.
The 288 just don't seem happy going down to 500 Hz. They will go up to about 15 kHz, though, and since I can't hear above 14 kHz any more (getting old is no fun), the 288 should do just fine as my tweeters.
Thanks.
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