Hi,
I'm looking at building a 2 way, it's my first time (only have experience building subwoofers and using rew/minidisp) and I'm going off some very rudimentary 'rules' I found online to find the drivers. I want to build it using 'PA' style woofers and a CD+horn, going for the 'cinema' experience.
As it's my first 'try', will be used in my home gym, I'm looking at some cheap drivers to see if I like it, if I do, I want to build all my speakers (5.1) for my home theatre.
I already bought my compression drivers, 1" BMS 4550 with RCH H100 horns. They have a nice extension and are quite cheap (200 euro for the pair incl horns)
I'm looking for the woofer, but I'm confused on the crossover.
BMS 4550: minimum crossover is 800Hz (seems very low for a 1")
JBL 2240h: maximum crosover is 800Hz (seems high for a 18"). I can get a pair for 250 euro which seems like a steal (I can probably still sell them afterwards if not used or recone to 2245h)
Would put the JBL in 400L tuned to 30Hz 'monster' cabinets, it extends nicely to 30Hz, and even with only 200Watts it gets plenty loud (116db according to winisd)
(one confusing thing on the 2240h, they mention in the documentation the vented version has less extension up high, but why? I always thought a vented cabinet acts like a sealed above the tuning frequency)
Beaming = 13740 / 18 = 763Hz, and I read it's only audible 1 octave about so about 1.5 Khz. So a 24db crossover at 800Hz should work in theory?
in 'theory' this should be fine, though, I read through a lot of threads saying a 18" should never be crossed over higher than 400Hz, preferably below 200Hz, as they start sounding 'muddy'. Also read the lower the Le, the better it is suited for a high crossover. It's a bit confusing, why would JBL put it's maximum crossover so high if it's no good? Also, how much can be resolved using REW and minidsp?
Alternative to the JBL would be a SB Audience 12MW200, it goes down to 50Hz so will need a subwoofer for the lowest notes, but has much less beaming, starts at 1145Hz for a 12".
Thanks!
I'm looking at building a 2 way, it's my first time (only have experience building subwoofers and using rew/minidisp) and I'm going off some very rudimentary 'rules' I found online to find the drivers. I want to build it using 'PA' style woofers and a CD+horn, going for the 'cinema' experience.
As it's my first 'try', will be used in my home gym, I'm looking at some cheap drivers to see if I like it, if I do, I want to build all my speakers (5.1) for my home theatre.
I already bought my compression drivers, 1" BMS 4550 with RCH H100 horns. They have a nice extension and are quite cheap (200 euro for the pair incl horns)
I'm looking for the woofer, but I'm confused on the crossover.
BMS 4550: minimum crossover is 800Hz (seems very low for a 1")
JBL 2240h: maximum crosover is 800Hz (seems high for a 18"). I can get a pair for 250 euro which seems like a steal (I can probably still sell them afterwards if not used or recone to 2245h)
Would put the JBL in 400L tuned to 30Hz 'monster' cabinets, it extends nicely to 30Hz, and even with only 200Watts it gets plenty loud (116db according to winisd)
(one confusing thing on the 2240h, they mention in the documentation the vented version has less extension up high, but why? I always thought a vented cabinet acts like a sealed above the tuning frequency)
Beaming = 13740 / 18 = 763Hz, and I read it's only audible 1 octave about so about 1.5 Khz. So a 24db crossover at 800Hz should work in theory?
in 'theory' this should be fine, though, I read through a lot of threads saying a 18" should never be crossed over higher than 400Hz, preferably below 200Hz, as they start sounding 'muddy'. Also read the lower the Le, the better it is suited for a high crossover. It's a bit confusing, why would JBL put it's maximum crossover so high if it's no good? Also, how much can be resolved using REW and minidsp?
Alternative to the JBL would be a SB Audience 12MW200, it goes down to 50Hz so will need a subwoofer for the lowest notes, but has much less beaming, starts at 1145Hz for a 12".
Thanks!
As far as crossing the compression tweeters low, it's usually fine in a domestic situation to go lower than resonance. 800Hz is not uncommon.
As far as crossing the woofers high, you have to catch them when they're beaming to cross them properly to the waveguides. This will be higher than other kinds of cross.. You don't get much choice here so the frequency depends on the size of the woofer.
As far as crossing the woofers high, you have to catch them when they're beaming to cross them properly to the waveguides. This will be higher than other kinds of cross.. You don't get much choice here so the frequency depends on the size of the woofer.
Ok, thanks! Regarding the CD, I'm indeed feeling quite 'ok' there as the sensitivity is crazy high so I won't exceed the xmax easily in a normal home situation.
The second, still sounds like Alien speak to me 🙂 how do I need to 'catch' them beaming? Also regarding the beaming, if for an 18" beaming starts around 800Hz, is is then fine to cross at 800Hz?
I can always just try it, the only downside of the JBL 2240H is the huge box they need
The second, still sounds like Alien speak to me 🙂 how do I need to 'catch' them beaming? Also regarding the beaming, if for an 18" beaming starts around 800Hz, is is then fine to cross at 800Hz?
I can always just try it, the only downside of the JBL 2240H is the huge box they need
Let me rephrase that.. they only beam by the right amount over a not so large frequency band. However yes, there is room for experimenting. Both woofer and waveguide may happen to vary a little to suit.
It looks like the vented response may include an ~800Hz second order crossover.
A vent has output well above Fb (box tuning) and would also have a pipe resonance peak and dip, but the response >800 should not change as in the frequency response depiction.
Although the BMS 4550 has a 44.4mm voice coil, the annular ring diaphragm has less displacement than a dome diaphragm of that diameter, at 800 Hz it will be displacement rather than power limited.
Sometimes a little visual explanation can help.
Try 'speaker directivity simulator' or 'speaker polar chart display' with value of your prefered driver and see if it match with your RCF waveguide's directivity @ 800hz. Try different size of drivers to see ... i would try a 12" first. 😉
Of course it's theorical and reality can vary, accomodate a bit of stretch, etc,etc,etc,...
https://www.tonestack.net/software/speaker-directivity-simulators.html
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