Greets!
Even early on, it was known from real world use that unless the driver's specs were very close, then they would need to be acoustically isolated if used at high power to down near/at Fs, box tuning since the most current 'hungry' one would 'hog' most of the power, potentially 'letting its smoke out' [self destructing].
Coupling drivers with diverse specs then was presumed to be an 'accident waiting to happen', so anyone that proposed it was normally 'shot down', but one man persevered, proving that a good performing hybrid was a viable alignment, ergo unless the driver's specs are far off enough to warrant 'doing the math' to a compromise alignment, no need to 'sweat' the small stuff', just brace them well [as in mechanically ty them together, so they can self damp each other].
Note that this is another way to implement a lower peak power handling 'FAST' alignment: http://community.fortunecity.ws/rivendell/xentar/1179/theory/dddllqd/dddllqd.html
GM
Even early on, it was known from real world use that unless the driver's specs were very close, then they would need to be acoustically isolated if used at high power to down near/at Fs, box tuning since the most current 'hungry' one would 'hog' most of the power, potentially 'letting its smoke out' [self destructing].
Coupling drivers with diverse specs then was presumed to be an 'accident waiting to happen', so anyone that proposed it was normally 'shot down', but one man persevered, proving that a good performing hybrid was a viable alignment, ergo unless the driver's specs are far off enough to warrant 'doing the math' to a compromise alignment, no need to 'sweat' the small stuff', just brace them well [as in mechanically ty them together, so they can self damp each other].
Note that this is another way to implement a lower peak power handling 'FAST' alignment: http://community.fortunecity.ws/rivendell/xentar/1179/theory/dddllqd/dddllqd.html
GM
Greg - of course this is another case of "it goes without saying" - actually, no Chris it doesn't 
, but yes in any of the cases of full range bipoles mentioned above that shared common volumes, the drivers were closely matched.
As the OP didn't indicate their specific reasoning / objective goals behind this project - other than possibly increasing effective amplifier power / total output level? - now might be a good time for that - there might be other approaches.
, but yes in any of the cases of full range bipoles mentioned above that shared common volumes, the drivers were closely matched. As the OP didn't indicate their specific reasoning / objective goals behind this project - other than possibly increasing effective amplifier power / total output level? - now might be a good time for that - there might be other approaches.
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Greg - of course this is another case of "it goes without saying" - actually, no Chris it doesn't
As the OP didn't indicate their specific reasoning / objective goals behind this project - other than possibly increasing effective amplifier power / total output level? - now might be a good time for that - there might be other approaches.
The 3 drivers are identical: Creative Sound - Product Details
Think Bose 901 but with each rear driver angled inward (as opposed to 901's rear drivers angled outward) to reflect off the rear then side walls.
The dispersion path of the fullrange drivers in the rear will criss-cross each other.
I only need to go down to 150HZ as I will be using a subwoofer so no filtering or crossover other than the sub crossover.
Any comments (good or bad) on this setup are more than welcome
Chris,
Hmm, I'm often a bit slow in posting these days, so was actually addressing just the OP............
As I alluded to though, and in retrospect probably should have been more succinct; as yours [and many others] experience has proven, it's highly doubtful he will have any problems with even a box full of like brand/model drivers in a common space, otherwise the line array folks would have spoken up long ago unless he band passes [XOs] them, which then will require the front driver to ideally be isolated [preferably sealed or at least ~aperiodic] lest the rears audibly modulate it on low [mid] bass notes.
Indeed, had I not wanted to periodically keep Thorsten's findings in the 'limelight' whenever it was a viable alternative, I would have passed on posting except maybe to
whoever posted what you did.
GM
Hmm, I'm often a bit slow in posting these days, so was actually addressing just the OP............
As I alluded to though, and in retrospect probably should have been more succinct; as yours [and many others] experience has proven, it's highly doubtful he will have any problems with even a box full of like brand/model drivers in a common space, otherwise the line array folks would have spoken up long ago
unless he band passes [XOs] them, which then will require the front driver to ideally be isolated [preferably sealed or at least ~aperiodic] lest the rears audibly modulate it on low [mid] bass notes.Indeed, had I not wanted to periodically keep Thorsten's findings in the 'limelight' whenever it was a viable alternative, I would have passed on posting except maybe to
whoever posted what you did.GM
'Sounds' like a plan, though ideally you'll need a 901 type controller to make it work well if no electronic filtering is used, unless.......
FWIW, I follow the old philosophy of acoustic solutions to acoustic problems, so when I've done similar, I damp any side/rear drivers with some form of phase plug or at least damping material, layering it on until I get the desired response at the listening position [LP].
GM
gee, codasm, you had to go and spoil it by alluding to Bose 901 - and before anyone flames me on that one, I have nothing personal against that venerated design - I've heard them and used them for small PA systems in the past - they're just not my cuppa java
actually, the CSS WR125 is in fact one of the drivers that were used in some of our bipoles "back in the day" - There were also an FR and /or 8 ohm versions with round frames.
Note that the combination of powerful XBL motors and high compliance suspension on these little guys made for alarming bass irregularities if enclosure doesn't provide sufficient loading, and/or if used with very low damping factor amps. In our case it was EL84 SE, I think, and not sufficiently loaded MLTL that made for disarming "flatulance" when the voice bottomed out on rear magnet plate. Best to try sealed, or very highly resistive aperiodic, along the lines of some of the designs here:
Frugal-phile | Box Library / CSS
Final thought is that if bass support is to be employed, there could be lots to gain from high-passing the wide band drivers - if a mono sub, perhaps lower than 150Hz to avoid potential discontinuity of lower mid bass imaging location - I usually never go above 100Hz myself.
- and before anyone flames me on that one, I have nothing personal against that venerated design - I've heard them and used them for small PA systems in the past - they're just not my cuppa javaactually, the CSS WR125 is in fact one of the drivers that were used in some of our bipoles "back in the day" - There were also an FR and /or 8 ohm versions with round frames.
Note that the combination of powerful XBL motors and high compliance suspension on these little guys made for alarming bass irregularities if enclosure doesn't provide sufficient loading, and/or if used with very low damping factor amps. In our case it was EL84 SE, I think, and not sufficiently loaded MLTL that made for disarming "flatulance" when the voice bottomed out on rear magnet plate. Best to try sealed, or very highly resistive aperiodic, along the lines of some of the designs here:
Frugal-phile | Box Library / CSS
Final thought is that if bass support is to be employed, there could be lots to gain from high-passing the wide band drivers - if a mono sub, perhaps lower than 150Hz to avoid potential discontinuity of lower mid bass imaging location - I usually never go above 100Hz myself.
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gee, codasm, you had to go and spoil it by alluding to Bose 901
actually, the CSS WR125 is in fact one of the drivers that were used in some of our bipoles "back in the day" - There were also an FR and /or 8 ohm versions with round frames.
Note that the combination of powerful XBL motors and high compliance suspension on these little guys made for alarming bass irregularities if enclosure doesn't provide sufficient loading, and/or if used with very low damping factor amps. In our case it was EL84 SE, I think, and not sufficiently loaded MLTL that made for disarming "flatulance" when the voice bottomed out on rear magnet plate. Best to try sealed, or very highly resistive aperiodic, along the lines of some of the designs here:
Frugal-phile | Box Library / CSS
I only need the fullrangers down to 150HZ - would this still be an issue as described above?
So its the angling of the rear drivers that would cause cavity issues as opposed to the way 901's rear drivers are angled?
The active equalizer in the bose 901 was implemented to boost the highs and the lows of the 901 drivers, drivers that by themselves are not able to reproduce a satisfying low or high end?
I'm using a sub for the low end and I feel the fullrangers I am using produce a sufficient enough high end.
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Ooh, forgot about that, my FR125S pair got bounced off the back plate several times while fine tuning the cab. Really frustrating that there's no audible onset of impending disaster, at least to older, well abuse ears anyway. Fortunately, they are well built as they're still doing fine all these years later.
Yeah, my early times with PC board XO'd subs only allowed a 120 Hz/2nd order, which with multiple large subs under the mains and with ~ two octave overlapping BW it was OK, but much prefer THX's reference 80 Hz/4th; though its cinema reference XO is 120 Hz/4th and sounds fine, so apparently a theater's acoustics combined with the subs close to the mains somehow makes it work.
GM
Going from a really dim memory since my experience with the 901 was back when it first came out, without the controller [it seemed to be much more than a simple high/low EQ, but a true programmed frequency shaping filter], they were completely un-listenable, with all sorts of tonal balance, comb filtering issues akin to a mob's unruly, incoherent cacophony.
As they cheapened the 901 up in later versions, it wouldn't surprise me if the controller was just an adjustable EQ. I remember auditioning a V4? at Best Buy and it was really sad sounding, but then around that same time, I helped install some prosound variants at local trade shows that were right impressive except for the outrageous pricing.
Properly set up as defined by B0s3 though, they did a better job overall on symphonies than the large cinema Altec VoTT horn system I had at the time, but that was pretty much it, though the owner was pleased since that's what he mainly wanted it for and kept his tube driven AR3 system for everything else.
Regardless, when using bi or di-poles, room acoustics gets complicated and unless the drivers are designed specifically for the app, then they usually require considerable tweaking to get the most out of them.
GM
thank-you so much everyone for all the feedback.
The reason for angling the rear drivers inward was to create more of a delay and isolate the rear drivers from the front driver somewhat - The front firing driver was to be mounted on a curved baffle to avoid diffraction as I wanted as clean a first arrival sound as possible.
but hearing things like 'cavity' have changed my mind about this build altogether.
Thanks again for the input and quite frankly am surprised how civil everyone remained at the mention of 901's
The reason for angling the rear drivers inward was to create more of a delay and isolate the rear drivers from the front driver somewhat - The front firing driver was to be mounted on a curved baffle to avoid diffraction as I wanted as clean a first arrival sound as possible.
but hearing things like 'cavity' have changed my mind about this build altogether.
Thanks again for the input and quite frankly am surprised how civil everyone remained at the mention of 901's
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