I have two P.Audio BM12CX38 coaxial speakers. View attachment P.Audio Coaxial Speakers - P.Audio BM12CX38 coaxial 12_ speaker - P.Audio BM12CX38 500 watt 12_ .pdf Actually I have 4, with two of them installed OB with subwoofers. A very nice speaker - and since I've lost some of my hearing in the upper ranges over my 60 years, the 18khz top end is not an issue really. I am pretty good with the wood working skills - not so much with the speaker and cross-over design software. I'd like to build a set of cabinets for them. What are my best bets?
Thx
Tris
Thx
Tris
Starting point for the crossovers to find the manufacturer's spec sheet with impedance and frequency plots, or measure them yourself.... It appears P Audio no longer has these on their web site.
You can model the cabinet with the specs you provided in a program such as Unibox or Winisd.
One website has this: " We recommend running the woofer fullrange and using a single capacitor for the tweeter", which makes it easy, IF you know the impedance of the tweeter at your chosen crossover frequency...
You can model the cabinet with the specs you provided in a program such as Unibox or Winisd.
One website has this: " We recommend running the woofer fullrange and using a single capacitor for the tweeter", which makes it easy, IF you know the impedance of the tweeter at your chosen crossover frequency...
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Not sure I understand.
PA can be very high-fidelity. My PA system measures as flat as my HiFi system, but the PA system has less harmonic distortion on account of the massive output capability.
Chris
I guess he meant either the factory crossovers or the factory curves in the data sheet. It can be quite tricky to design a proper crossover for some coaxials.
Regards
Charles
Regards
Charles
Get hold of Danny Richie at GR Research he has a load of experience with that driver. I know he has a x over for it!
I've seen his videos on YouTube, and it looks like he knows what he's doing. That would definitely be the person to ask.
It looks like he makes a nice improvement to the Klipsch RP-600M - Upgrade your Klipsch RP-600M! pt.1 - YouTube
The other two drivers I refer to are from Danny's Super V speaker system that I have. I have the cross overs for that but they're designed to run this driver OB. I could certainly ask him to design me a cross over and a cabinet but he's a busy man running a small niche market business and I'm sure he doesn't have time to poke around with this.
I'm aware that their are a lot of hobbyists out there who play around with the different software available who might enjoy helping me along here and that's what I'm looking for. Tech Talk at PA is a good suggestion. I'm trying other forums as well.
Thx for all the replies.
Tris
Have worked extensively with the BM18CX38 in OB and enclosures applications. Still have a pair. Yes, you can do a cheap and easy single cap (with pad resistor) on the H.F. crossover and get so - so results. But to really sing, you need a proper crossover. You HAVE TO measure your drivers before you do anything. The BM coax's can very quite a bit and rarely meet published specifications. Building a crossover & enclosures with out knowing exactly what you have is a crap shoot. Do you have any way to measure them? The Parts Express DATS tool would tell you what you need to know. J
Hello John
I have REW and most of the requisite gear. I was going to actually haul one of my OB "cabinets" outside to the backyard and give them a measure as I've been messing with a 4x10 miniDSP and thought this would be much better than trying to use gated measurements. Unfortunately it's been lousy weather for a while and winter is sneaking up on us here already...
Are you suggesting I should be measuring both drivers regardless then? What is the best way to measure a raw driver?
PS: Lost interest in things so-so when I hit 50.
Thx
Tris
I have REW and most of the requisite gear. I was going to actually haul one of my OB "cabinets" outside to the backyard and give them a measure as I've been messing with a 4x10 miniDSP and thought this would be much better than trying to use gated measurements. Unfortunately it's been lousy weather for a while and winter is sneaking up on us here already...
Are you suggesting I should be measuring both drivers regardless then? What is the best way to measure a raw driver?
PS: Lost interest in things so-so when I hit 50.
Thx
Tris
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Well if he already has this available, then asking shouldn't be too much of a bother. I will try that avenue as well. Much appreciated.
Still would like to know about measuring the raw driver.
Tris
Still would like to know about measuring the raw driver.
Tris
Had a play with these in Unibox; that main thing is that with a low Qts of 0.19 they're really only suitable for an EBS alignment, they start to drop off below 180 Hz. Don't need too large a box, I got 55 litres tuned to 40Hz, with 40- 100 Hz down ~ 6 dB. If you like bass, perhaps the second pair could be crossed over at ~ 180hz as a .5 way woofer??? Would require a large inductor though.
Danny was nice to suggest a network for my 12CXA coax - but the lowpass (3mH coil) which apparently worked well for open baffle, was wrong for the speaker sitting back in a Karlson as BSC isn't needed. In my case I figure a 2nd order lowpass set to "boost" (by lower Z in its upper region) will work. A 3.3uF cap made a good highpass for 12CXA's BM 450 compression driver - dunno about your large format CD. Danny could help there.
Sometimes a tall MLTL can help fill in a dip which can occur with low qts and more cubical bass reflex - - something like a 12 inch version of Zu's old "Druid".
Sometimes a tall MLTL can help fill in a dip which can occur with low qts and more cubical bass reflex - - something like a 12 inch version of Zu's old "Druid".
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Thx PeteMcK
The second pair are in an OB set up and I don't have plans on using them for this. These 2 drivers will have to stand on their own but I can't see why they wouldn't. If I need subs I can deal with that separately but a ported cabinet should get me down there pretty decently regardless.
A quick google of EBS does not make me much smarter.
Tris.
The second pair are in an OB set up and I don't have plans on using them for this. These 2 drivers will have to stand on their own but I can't see why they wouldn't. If I need subs I can deal with that separately but a ported cabinet should get me down there pretty decently regardless.
A quick google of EBS does not make me much smarter.
Tris.
It's where the low frequencies shelve down.
Top line is obviously a flat response, next one down is -3db EBS (Extended Bass Shelf), bottom is -6db EBS.
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