Shaddai,
The B&C 18DS100-4 TS parameters are fairly close to the 18SW115-4, but a bit less power and BL/Xvar. Should work OK, though I'd pay the extra money for the 18SW115's bigger voice coil and heavier magnet and proven results.
That said, if anyone has actually done the real comparison, would like to hear about it.
Art
The B&C 18DS100-4 TS parameters are fairly close to the 18SW115-4, but a bit less power and BL/Xvar. Should work OK, though I'd pay the extra money for the 18SW115's bigger voice coil and heavier magnet and proven results.
That said, if anyone has actually done the real comparison, would like to hear about it.
Art
Well, I'd be willing to take a crack at running some tests with that driver if I can get my mits on them early enough. I'm building 4 Keystones, but, they're due to go out on heir first job on 9/19. Unfortunately, the driver choice between the 4 B&C drivers that look like they'd work is partially dependent on which driver I can get here by 9/17 or 9/18 
If you (Art) give it a vote of confidence that I'm not going to build a fleet of 'can't get them rented' duds, then I'd be willing to pursue those 18DS100's & report back what I find out.
If you (Art) give it a vote of confidence that I'm not going to build a fleet of 'can't get them rented' duds, then I'd be willing to pursue those 18DS100's & report back what I find out.
The 18TBW100-4 has less BL than the 18DS100, and had good output, so I'm fairly confident the 18DS100 should be plenty "good enough for rental". The differences between cones of the quality you are considering is way less than the differences you will hear between track to track, performer to performer, or room to room.
Be careful, don't loose any fingers trying to finish too fast!
Art
Be careful, don't loose any fingers trying to finish too fast!
Art
Alright another beginner question. My keystones are now assembled and initial test is incredibly impressive, way more than what I was expecting. I remember reading, but cannot find, about the delay required for the tops. I also remember reading about the driverack having reverse polarity output from input, but again I can't seem to find in the thread (I'm using the pa2 if it matters). Basically I'm needing to know if I need to inverse the polarity in the driverack and also the delay I need to put on the tops. Thanks so much in advance.
It'll vary according to your mid-high speakers, desired crossover frequency & slopes, physical placement, etc.
If you'll always have your mains and subs co-located (ie, stacked), then you can dial something in once. Otherwise, you'll need to get things align on a per-deployment basis.
Chris
If you'll always have your mains and subs co-located (ie, stacked), then you can dial something in once. Otherwise, you'll need to get things align on a per-deployment basis.
Chris
The DBX DRPA has all outputs reversed in polarity from the input, no consequence if used by itself.
I can't recall for sure, but it seems someone found the mid outputs to be polarity reversed on the PA2 or +.
As Chris mentioned, delay will depend on your mid-high speakers, crossover frequency & slopes, physical placement, and also the type of processor you are using, there is a DSP "Tower of Babel"
DSP Tower of Babel
DSP Tower of Babel | Sound Forums
The path length of the Keystone adds just over 10ms of "time of flight". The DBX DRPA has 10ms delay, which was "just enough" for the tops I was using..
Art
Hi! I am currently in the process of building two Keystones loaded with BnC tbw100-4 drivers powered by a NX6000D. I have been trying to decipher exactly how i should be setting the limits on the amp to avoid any expensive mistakes when using the system at full tilt. It will primarily be used for playing EDM. Mostly House/Techno and a bit of Drum and Bass and Dubstep. My biggest concern would be with some of the dubstep songs having very long sustained basslines. From what i have read it seems important to set a HP filter around 30-35 hz and a low pass filter from 90-105hz. Should I also be setting a limiter to around 1200 watts on the amp or is that not necessary if the proper HP filter is set? I have only used powered speakers before for PA which have proven fairly "dummy" proof especially with the technology these days. They usually have limit lights for both amp clipping and thermal protection baked in to the subs so its pretty hard to mess them up.
FinkNewton,
The following is the same advice as in the original post, with the B&C18TBW100-4 specifications substituted.
Compressor/limiters will not protect a loudspeaker from excursion related mechanical damage.
Your Keystone sub should use a 30Hz 24 dB per octave Butterworth high pass filter to protect drivers from mechanical damage if amplification capable of exceeding the driver's Xmech rating are used. The B&C18TBW100-4 Xmech is 28.5mm (57mm peak-to-peak excursion before damage)
To set Compressor/limiters for protection against thermal damage:
A) Use the DCR of the loudspeaker to determine the voltage setting, the DCR of the B&C18TBW100-4 is 3.2 ohms, the minimum impedance of it loaded in the Keystone Sub approaches that value at Fb, where cone movement (and forced air cooling) is also at minimum.
B) The manufacturer's "Continuous Program" rating of 3000 watts is OK for peak limiting, using short time constants of a few wavelengths duration.
C) Long term "RMS" limiting with a time constant of longer than 500 ms (milliseconds) should be no more than half the rating of 1500 watts (750 watts), as AES ratings are conducted in free air (the actual power dissipated is less than 1/2 the nominal "wattage"), while driver's voice coils heat up far more when loaded in the Keystone "tapped horn" due to the far lower average impedance than the free air test. If you tend to get "heavy handed" on the volume fader playing compressed music over long time periods, use 375 watts.
If using other drivers, substitute their "Continuous Program" and 1/4 to 1/2 of the "Nominal" RMS rating for peak and average limiting settings, using the DC resistance, not the nominal speaker impedance for figuring the compressor/limiter threshold voltage settings.
Art
The following is the same advice as in the original post, with the B&C18TBW100-4 specifications substituted.
Compressor/limiters will not protect a loudspeaker from excursion related mechanical damage.
Your Keystone sub should use a 30Hz 24 dB per octave Butterworth high pass filter to protect drivers from mechanical damage if amplification capable of exceeding the driver's Xmech rating are used. The B&C18TBW100-4 Xmech is 28.5mm (57mm peak-to-peak excursion before damage)
To set Compressor/limiters for protection against thermal damage:
A) Use the DCR of the loudspeaker to determine the voltage setting, the DCR of the B&C18TBW100-4 is 3.2 ohms, the minimum impedance of it loaded in the Keystone Sub approaches that value at Fb, where cone movement (and forced air cooling) is also at minimum.
B) The manufacturer's "Continuous Program" rating of 3000 watts is OK for peak limiting, using short time constants of a few wavelengths duration.
C) Long term "RMS" limiting with a time constant of longer than 500 ms (milliseconds) should be no more than half the rating of 1500 watts (750 watts), as AES ratings are conducted in free air (the actual power dissipated is less than 1/2 the nominal "wattage"), while driver's voice coils heat up far more when loaded in the Keystone "tapped horn" due to the far lower average impedance than the free air test. If you tend to get "heavy handed" on the volume fader playing compressed music over long time periods, use 375 watts.
If using other drivers, substitute their "Continuous Program" and 1/4 to 1/2 of the "Nominal" RMS rating for peak and average limiting settings, using the DC resistance, not the nominal speaker impedance for figuring the compressor/limiter threshold voltage settings.
Art
Thanks Art! I really appreciate the quick and detailed response! Really excited to get these speakers fired up in the next week or so once the amplifier arrives. It has been really fun building these with a couple friends and we are really stoked to hear them in action! Ill be sure to post some pictures on here once we have them painted and finished.
Soooo, I built 4 of them with the 18DS100-4 drivers, and I finally plugged 2 of them to a PL4.0 last night. I set a 30hz HPF, randomly picked a crossover point (90 I think), and plugged a pair of SR4732's on a PL2.0 amp just to have some top end. I just wanted to hear them go, even without a dialed in setup. I stepped on the gas a bit & the first lesson I learned is that 20 amps of 120V doesn't like that
There's some DSP work to do, but my first impression is that these cabinets with this driver would happily out run the 4732's without trying very hard. Even with my power limitation, they sound solid, effortless & musical... there's just no 'sloppiness' in them. Without power struggles & probably some more amplifier, they'd be monsters. Anyone have a K3 or two floating around they want to send me?
Anyway, I couldn't quite get to knocking things over, but I did get to vibrate my shirt, blur my vision, rattle the plates in the kitchen & knock a bunch of dust out of the rafters if that counts.
Pretty happy with them so far. I'll plug the RTA mic in & play some today to see what happens.
Todd
There's some DSP work to do, but my first impression is that these cabinets with this driver would happily out run the 4732's without trying very hard. Even with my power limitation, they sound solid, effortless & musical... there's just no 'sloppiness' in them. Without power struggles & probably some more amplifier, they'd be monsters. Anyone have a K3 or two floating around they want to send me?
Anyway, I couldn't quite get to knocking things over, but I did get to vibrate my shirt, blur my vision, rattle the plates in the kitchen & knock a bunch of dust out of the rafters if that counts.
Pretty happy with them so far. I'll plug the RTA mic in & play some today to see what happens.
Todd
@Art - forgive me if this was in a previous post, but has this been tested with the B&C 21SW115? Or any other 21" driver? I'm curious if there's a benefit to the extra few inches and lower response of these vs the normal 18". I plan on building four Keystones before summer this year. I know the 18 will be fine for what I'm doing, but I'm always looking to push a little more than my competition in the area.
I don't recall anyone actually reporting using 21" drivers in the Keystone.
Using Hornresp simulations, the the B&C 21SW152 required 800 more watts to achieve another 1.5 dB output than the 18SW115, not much of a difference in output. The lighter B&C 21SW115 may not require as much power to reach a similar small increase in output.
Art
Using Hornresp simulations, the the B&C 21SW152 required 800 more watts to achieve another 1.5 dB output than the 18SW115, not much of a difference in output. The lighter B&C 21SW115 may not require as much power to reach a similar small increase in output.
Art
Art, what do you think about using an 18 sound 18nlw9000 in this box.
Used it for year's in a kind of xoc style tapped horn but they're tired now and looking to try something new.
Eighteen Sound 18NLW9000 - 18" Subwoofer
Used it for year's in a kind of xoc style tapped horn but they're tired now and looking to try something new.
Eighteen Sound 18NLW9000 - 18" Subwoofer
Billy,
The Mmd 18NLW9000 of 218g seems a bit light by comparison to the 18NLW9601 at 255g or the BC18SW115 at 275g, the lighter cone may sound distorted before reaching Xmax.
That said, if you were happy with the performance of the 18NLW9000 in the xoc style tapped horn, you probably would be happy with it in the Keystone.
PASC built a Keystone Sub TH ("tapped horn") and a xoc1 18" TH and reported his findings in posts #114, 115 & 118. "Comparing with TH18 Xoc1 style, cone control is impressive."
Art
The Mmd 18NLW9000 of 218g seems a bit light by comparison to the 18NLW9601 at 255g or the BC18SW115 at 275g, the lighter cone may sound distorted before reaching Xmax.
That said, if you were happy with the performance of the 18NLW9000 in the xoc style tapped horn, you probably would be happy with it in the Keystone.
PASC built a Keystone Sub TH ("tapped horn") and a xoc1 18" TH and reported his findings in posts #114, 115 & 118. "Comparing with TH18 Xoc1 style, cone control is impressive."
Art