Hi all,
I'm itching to try a different design from my normal work, which could best be characterized as high quality PA builds.
The floor-the-ceiling line arrays, made to go into room corners, look particularly good to me.
From researching many line array threads, I've seen that the floor and ceiling are supposed to extend the line's length, perhaps theoretically infinitely...
I take this to be a very good thing...
But I also see more and more commercial column designs promoting beem steering such as one just announced by RCF.. Product Detail - RCF
I get that commercial designs are unlikely to be able to match ceiling height and thus take advantage of extending from floor-to-ceiling. So it seems vertical pattern control could be very beneficial then.
My question is: with a normal 8ft or so ceiling, do you see beem steering such as in the RCF being an advantage?
Or does the non-steered, reflection extended line from the floor and ceiling totally suffice? Would the extended line be harmed be steering?
I realize the need for discrete control of all the drivers in the line...I'm just trying to decide if it would be worth the effort to attempt building in steering capability.
(So far, looking at the usual 3 1/2" drivers... Yikes the channels !!)
Thx... mark
I'm itching to try a different design from my normal work, which could best be characterized as high quality PA builds.
The floor-the-ceiling line arrays, made to go into room corners, look particularly good to me.
From researching many line array threads, I've seen that the floor and ceiling are supposed to extend the line's length, perhaps theoretically infinitely...
I take this to be a very good thing...
But I also see more and more commercial column designs promoting beem steering such as one just announced by RCF.. Product Detail - RCF
I get that commercial designs are unlikely to be able to match ceiling height and thus take advantage of extending from floor-to-ceiling. So it seems vertical pattern control could be very beneficial then.
My question is: with a normal 8ft or so ceiling, do you see beem steering such as in the RCF being an advantage?
Or does the non-steered, reflection extended line from the floor and ceiling totally suffice? Would the extended line be harmed be steering?
I realize the need for discrete control of all the drivers in the line...I'm just trying to decide if it would be worth the effort to attempt building in steering capability.
(So far, looking at the usual 3 1/2" drivers... Yikes the channels !!)
Thx... mark
The Infinite Line Source: analysis thread goes into the theory behind the infinite array approach. The arrays used in PA are not able to use floor/ceiling "mirror images" to virtually lengthen the array.
The CBT from Keele uses the floor and the top end is shaded which could be seen as a steering mechanism. For a finite array this could be a viable option. Shading a floor to ceiling array in a similar way would definitely mess with the floor and ceiling "mirror images". No floor or ceiling is going to be a pure sonic mirror though, so in practice things might actually work out pretty good, I haven't tried it on a straight array.
Personally, I opted to get as close as possible to that infinite line source ideal. Even though my array isn't extending all the way up to the ceiling. About 70% (or more) coverage of the floor to ceiling distance is often considered to be enough to still 'see' the advantages as a general rule of thumb.
The CBT from Keele uses the floor and the top end is shaded which could be seen as a steering mechanism. For a finite array this could be a viable option. Shading a floor to ceiling array in a similar way would definitely mess with the floor and ceiling "mirror images". No floor or ceiling is going to be a pure sonic mirror though, so in practice things might actually work out pretty good, I haven't tried it on a straight array.
Personally, I opted to get as close as possible to that infinite line source ideal. Even though my array isn't extending all the way up to the ceiling. About 70% (or more) coverage of the floor to ceiling distance is often considered to be enough to still 'see' the advantages as a general rule of thumb.
Steering in the way RCF does requires many amplifier and DSP channels and modelling that is outside the scope of most DIY guys. It mostly seems to add flexibility, allowing for the vertical coverage pattern to be set to what is needed in a certain venue. I do not think this adds value to a one-off loudspeaker that you design specifically for your home, with prior knowledge about what your home looks like. It can also be used to get even pattern control from a line that otherwise would be too short, which does not apply if a full length floor to ceiling array is an option.
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Hi Wesayso, and thanks!
Yep, I've read that thread and others about the CBT.
My thoughts match what you say,.... that any steering would have to mess up the "mirror-lines" ....but also then again, who knows how well the floor and ceiling are making the sonic mirrors....
So I'm kinda thinking maybe to build in steering....on a build just under 8ft long for my normal sized room. Just to compare...
I have a room with a tall vaulted ceiling, that I'd also like to try the build in. Thinking steering might be valuable there...
But of course, there's the reality cost of all the necessary channels.......aargh..
Yep, I've read that thread and others about the CBT.
My thoughts match what you say,.... that any steering would have to mess up the "mirror-lines" ....but also then again, who knows how well the floor and ceiling are making the sonic mirrors....
So I'm kinda thinking maybe to build in steering....on a build just under 8ft long for my normal sized room. Just to compare...
I have a room with a tall vaulted ceiling, that I'd also like to try the build in. Thinking steering might be valuable there...
But of course, there's the reality cost of all the necessary channels.......aargh..
Yep, thx.
I get the amp/DSP implementation demands....I think I'm OK there.
If I was building solely for placement in one room, I don't think I'd even consider it.
But I REALLY like to move gear around, room to room, etc.
I find that is often the best thing I can do to make a system shine...horses for courses so to speak.
And the RCF steering just looks so dang interesting too!
Getting tempted Lol
I'd see more value in a very closed space WMTMW (basically what a synergy horn is) and extending that on both sides with a bass array (so on top and bottom), making it sort of an an expanding array that all seems to come from a virtual point source. The bass array would make use of the floor and ceiling and thus avoid the reflections in a vertical plane, the horn avoids the rest trough it's pattern control.
Or something like the paraline array from Danley which still mimics that point source ideal by bending the resulting wave shape with it's lenses.
Or something like the paraline array from Danley which still mimics that point source ideal by bending the resulting wave shape with it's lenses.
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Yeah, the synergies really do make sense.
But I kinda feel I have very close to a synergy already, with a build that has a coaxial CD mounted in between horn loaded mids (the Peter Morris boxes)
I don't have any desire to get bass above and below .... I honestly don't think there is any sense in trying to direct bass (100Hz sub xover).
I'm happy just keeping the floor sub within 100Hz 1/4 WL, of main speaker.
I sense a synergy project would be more lateral in nature to my existing speakers, and am thinking a line-array would be spankin new territory ...
Paraline is too much acoustic plumbing I think....
So studying drivers right now...ye ole TC9FD looks like a good benchmark
If you're planning to use sub support anyway, you could go for smaller drivers, like the SB Acoustics SB65WBAC25-4, just more of them as they would give you closer spacing in a straight line than the 3.5" drivers. They look cute in person! But they are also quite impressive drivers!
I'd still stick to keeping floor to ceiling a line array to behave as a line source, as opposed to using beem steering with it. I'd only use that principle with finite arrays.
I'd still stick to keeping floor to ceiling a line array to behave as a line source, as opposed to using beem steering with it. I'd only use that principle with finite arrays.
Looks like a very nice driver !
I'd like to keep driver cost down on building a "first try" experimental column.
So driver cost is a constraint, and fewer drivers are better.
The other constraint is, if I continue with the goal of beam steering, I currently have at most 24 channels of amp & dsp using the same platform. So ideally 24 drivers max (for one speaker)
But 24 drivers doesn't get me near 8ft tall with any drivers I've found, that are both affordable for an experiment, and have good VHF response.
I figure I can group drivers at the array center to overcome the 24 driver constraint and still beam steer, but still, more complication....
My gut says all arrays are finite, floor and ceiling mirrors or not,...hope my gut gets proven wrong !! Really hope...
Wouldn't mind beam steering to be totally worthless for floor-to-ceiling.
Without the perfect environment, how would one now? And what is that perfect environment?
At least floor reflections are real (as far as I've seen them), just carry your favourite 3 way into the room and measure. Straight arrays are overly sensitive to parallel planes/ridges etc. to the array. Even if you tuck it away in a corner, there's still the transition from baffle to the wall to deal with.
Be sure to do everything you can to fight diffraction in your design or that may lead you to wrong conclusions.
It's not going to be easy... A CBT would be less sensitive to these parallel planes, as the driver distances vary in two planes. But I wouldn't do one extended all the way to the ceiling. Bend it the other way and it will give you a focussed array with it's own set of drawbacks, except in it's sweet spot.
I'd give up the cost for 22 of the 24 channels of amplification and go for the smaller drivers.
From all my experiments so far, getting the speaker to work together with the room is the way to more pleasing sound.
At least floor reflections are real (as far as I've seen them), just carry your favourite 3 way into the room and measure. Straight arrays are overly sensitive to parallel planes/ridges etc. to the array. Even if you tuck it away in a corner, there's still the transition from baffle to the wall to deal with.
Be sure to do everything you can to fight diffraction in your design or that may lead you to wrong conclusions.
It's not going to be easy... A CBT would be less sensitive to these parallel planes, as the driver distances vary in two planes. But I wouldn't do one extended all the way to the ceiling. Bend it the other way and it will give you a focussed array with it's own set of drawbacks, except in it's sweet spot.
I'd give up the cost for 22 of the 24 channels of amplification and go for the smaller drivers.
From all my experiments so far, getting the speaker to work together with the room is the way to more pleasing sound.
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Our experience is that every type of arrays got it's own strengts and drawbacks. We have built vertikal unshaded arrays, vertikal shaded arrays, CBT and focussed arrays. Differences are easily detected. Best image, pinpoint and dynamics goes to the focussed array, in the sweet spot of course. CBT give mostly rich and even sound all over the room, but with less pinpointing. Vertikal unshaded array offer good dynamics and vertical dispersion with pinpointing helped by HAAS-effect, but with somewhat bigger than life image. Vertikal shaded array is a good compromise IMHO when it comes to vocal and acoustic jazz etc. as the sound do not swell that much (less delays from ceilings etc). We did our observations in a normal living room without any acoustical treatments.
This is my "cheap" build. Maybe 350USD for the pair. I love them and I will seriously consider a more elaborate build once my living location for the future is settled. Prepare for EQ and quite some power at hand. Also, prepare for a bass "null" in the place where you would like to sit - I don't know if this is mandatory but I have a hunch it might be considering the involved geometry.
My FR10HM corner-ceiling-floor-array
- I don't know if this is mandatory but I have a hunch it might be considering the involved geometry.My FR10HM corner-ceiling-floor-array
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Well, this is exactly the reason I mentioned the room and it's influence to Mark in my reply. I have straight unshaded arrays but no larger than life image. As I've said on my thread: the FIR filtering alone "shrunk" or "tamed" my arrays. And that was a few days in on starting with FIR filtering. I continued to test and observe frequency dependent shading schemes and cooked up a recipe that worked for me in my room.
And I bet one could do the same/something similar with the CBT too! I don't have an untreated room as even before getting into this project I had the plans to get rid of all early reflections without turning my living room into a studio
.So I don't much like the generalisations even when based on actual builds, without looking what caused this. Get the data at the listening spot, analyse that data and act upon it. Instead of building lord knows how many speakers I have decided to stick to one concept and optimise it (and it's environment).
You could do that with almost any sort of speaker. But there are many variables at play here and one cannot ignore any one of those and draw conclusions from it.
Look at the graphs, listen to it, change one thing and do it again. Over and over again
.Yes, you can achieve your favourite soundscape by those measurements. My point is that each basic design got its own identity (in nude).
Non-diy'ers buying their line array without the necessary knowledge, room or equipment should be aware of this.
I will even build more speakers, but different ;-)
Non-diy'ers buying their line array without the necessary knowledge, room or equipment should be aware of this.
I will even build more speakers, but different ;-)
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Thanks guys,I totally get the role of the room, and resonate strongly with all comments regarding its overarching role.
Maybe a little background will help explain my line array design goals, and why I'm not trying to build to a particular room.
I've been fortunate to have been able to optimize several rooms acoustically over the years ...rooms where audio was the first priority...no WAF allowed Lol..
Anyway, I could go into the lengths i took, but for brevity just let me say I absolutely understand the value of optimizing room acoustics. Often more important than a whole lot of speaker work we do imho.
But the best room I ever hear....is no room...outdoors. I simply love a good powerful rig set up outdoors. It makes whatever I do indoors sound so poor in comparison, I refuse to tune to a room any longer.
Plus I don't like a 'listening spot' anymore...I move around and dance...with the ladies
i like to listen from adjacent rooms etc...
Too many years sitting with my head in a vise in front of electrostats i guess..
So bottom line...I want a flexible line....array that is
Hence the desire to play with steering...
Ron, I hear you preferring the smaller drivers in lieu of dsp/amps.
But the thing is, I already have the dsp/amps...the driver cost really comes down to the marginal cost to try this...and I'm looking more to experiment than trying to build a new main system.
The TC9FD and PS-95-8 are my current front runners unless advised elsewhere...
I say i already have amps, but that's not entirely true. I have 16 identical channels of 1150W, and another 8 channels of 600W or greater from a kludge of different amps. And they are used elsewhere.
If the line steering pans out as desirable, I'll want to replace all of them with some low wattage, inexpensive stuff. Recommendations will be needed..
TNT, looks nicely done on budget! What do you mean by bass null where you sit?
Wilbur-x, thx again, exactly the kind of info hoping for.
What do you mean by focused array? Or rather, how does focused differ from shaded? If shaded means amplitude varies, and focused means time varies, I think I get it. Otherwise, I'm not understanding...
Mark, I think steering could make sense if you don't want to adjust the space to the speakers. A focused array would have all drivers equal distance to one listening position.
Think of an arc shape with the center point at your ear as a passive example. With steering you could mimic that with delay and possibly SPL manipulation although it wouldn't be exactly the same.
The straight array could also mimic the CBT with shading and delay as those JBL CBT line arrays do.
Possibly the truly arched CBT arrays would be most independent from the room they are in.
Think of an arc shape with the center point at your ear as a passive example. With steering you could mimic that with delay and possibly SPL manipulation although it wouldn't be exactly the same.
The straight array could also mimic the CBT with shading and delay as those JBL CBT line arrays do.
Possibly the truly arched CBT arrays would be most independent from the room they are in.
Let me add a few thoughts on my listening to the Modified CBT24s that I completed in early 2018. After building and listening to straight line near field arrays for years, the CBTs yield a sound in my room that is more uniform and consistent throughout the room. My living room is 23 feet wide by 32 feet long with a ceiling height that extends to an apex of 18 feet across the center of the room. Thus we are talking a large/tall room that would be an echo chamber for a point source loudspeaker.
My arrays are just over 5 feet high and they benefit from the mirror image from the floor (ground plane). The SB Acoustics SB65WBAC25-4 drivers (about 2.5" square) is the driver used in my build.
CBT Godfather Don Keele's comments about the coverage of a CBT : "Constant beamwidth, constant directivity, constant coverage, constant radiated power."
I'm hearing the same sound in my listening room with my CBTs. Your CBT creates a 'sweet room' effect versus just a 'sweet spot'.
My project is detailed in this thread:
My New Line Array--It's a Modified CBT24
If the original poster wishes to have great sound all over his room, then a CBT is superior. His steered array idea sounds like a complex local science fair project.
Jim
My arrays are just over 5 feet high and they benefit from the mirror image from the floor (ground plane). The SB Acoustics SB65WBAC25-4 drivers (about 2.5" square) is the driver used in my build.
CBT Godfather Don Keele's comments about the coverage of a CBT : "Constant beamwidth, constant directivity, constant coverage, constant radiated power."
I'm hearing the same sound in my listening room with my CBTs. Your CBT creates a 'sweet room' effect versus just a 'sweet spot'.
My project is detailed in this thread:
My New Line Array--It's a Modified CBT24
If the original poster wishes to have great sound all over his room, then a CBT is superior. His steered array idea sounds like a complex local science fair project.
Jim
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