Sims are great, but the real measurement shows even better response:
And of course, in listening, it is no problem at all as you noted, Rob. The key is to listen at a sufficient distance away from the array. I said this before but it bears repeating: As we move away from the array, the interunit spacing becomes smaller as seen from the measurement point, and this pushes up the frequency where comb-filtering begins to appear. In my case, by 12 ft, the interunit spacing (about 3.5 in.) is negligible compared to the distance away from the array. At that distance, only the very high frequencies (with very small wavelengths) have appreciable phase shift from unit to unit to cause the peaks and dips. At lower frequencies, it is basically adding in phase.
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Not sure you saw these posts with real distance and height measurements:
http://www.diyaudio.com/forums/mult...line-array-using-vifa-tc9-13.html#post4584857
No, I'm just surprised to see such a distinct falling response from this driver. For years I've been told that combining a lot of small drivers into a line array will help their bass response. Well I didn't expect it to help so much!
No doubt you have it under control with EQ.
FWIW I love multi-cell horns (as you know). I keep being told how badly they comb. But I never heard it unless very close to them. No one else who heard mine has complained about it either.
Wow, excellent work ra7. Your measurements certainly shed some light on what's happening with floor to ceiling line arrays. I think my measurements would have similar results even though mine aren't corner arrays and the mids are open baffle.
I wanted to use the ceiling and floor to my advantage which is why I built floor to ceiling arrays. Using corner arrays like you did also makes use of the side walls rather than creating issues with reflections. I wish I had a room suitable for a design like yours.
Yeah, some of the time arrival differences are visible in the 3 ft impulse response. Like I said, as you move away from the array, the phase shifts from individual units are so random, that it ends up adding to the response.
Btw, I hooked up the EMU 0204 directly to the amp for this measurement and I had to measure at -50 db to keep the volume reasonable. These arrays are very efficient. I'll do an absolute measurement to see if I can determine their efficiency. Distortion is obviously low and low-level detail retrieval is excellent. In fact, even on very low volumes, everything is so crystal clear. It really is quite different from a point source at low volumes.
Because the vertical response of a planar is much different from that of a round 3.5" cone driver hence why ribbons and planars are the preferred HF device for arrays.
My corner line arrays might be 2-ways, multiple 4" cones and a single Fountek Neo 5i or 3.5H at ear height... Array enclosure divided in cells of 3-4 stacked woofers. Products_Fountek Electronics Co.,Ltd
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I wish I had measured the Neo8 planars when I had them, but I just sold them recently. I am not sure they behave too differently than a regular cone when it comes to HF dispersion. Besides, I have shown through measurements that comb filtering is simply not happening at normal listening distances with an array of 3.5 in. full range drivers. That combined with the listening experiences of at least three folks in this thread should be enough proof that comb filtering is not an audible problem. You can of course continue to challenge this claim, but at this point some measurements to show proof would be highly appreciated. I am genuinely interested in seeing the vertical response of planars, but I haven't seen such measurements before.
Juhazi, I see what you're doing, I get what you're planning on doing, but still I wouldn't (didn't actually) do it.
Your proposed array here has certainly been tried before many times. maybe not in a corner but in my humble view you would miss out on a large part that makes this floor to ceiling array work.
But if you do decide to do it, I know many viewing a thread like this, or my thread for that matter, might start thinking about building floor to ceiling arrays and I can't blame them. I'd even encourage that. Know this before you start: pick the right driver for the job.
Even though many wouldn't look twice at a budget driver like the Vifa's TC9, I picked that one because it was one of the best candidates for that job. It certainly wasn't a price consideration. I would pick it again in a heartbeat and haven't seen many alternatives beside very close relatives to that TC9.
Your proposed array here has certainly been tried before many times. maybe not in a corner but in my humble view you would miss out on a large part that makes this floor to ceiling array work.
But if you do decide to do it, I know many viewing a thread like this, or my thread for that matter, might start thinking about building floor to ceiling arrays and I can't blame them. I'd even encourage that. Know this before you start: pick the right driver for the job.
Even though many wouldn't look twice at a budget driver like the Vifa's TC9, I picked that one because it was one of the best candidates for that job. It certainly wasn't a price consideration. I would pick it again in a heartbeat and haven't seen many alternatives beside very close relatives to that TC9.
My corner line arrays might be 2-ways, multiple 4" cones and a single Fountek Neo 5i or 3.5H at ear height... Array enclosure divided in cells of 3-4 stacked woofers. Products_Fountek Electronics Co.,Ltd
That may work very well if the XO is 5k then all the comb stuff in the sims won't be there. However you will have sound integration issues with the different locations of the mids at the extremities vs where the tweeter is.
I wish Owen (member: OPC) would chime in with his personal experience. He was one of the first (might even be the first) with floor to ceiling arrays sporting the Vifa TC9. I stumbled over his posts when I was planning mine when his post came up in a search on my chosen driver and arrays. He later acquired the Bohlender-Graebener RD-75. If there's one person on here that could answer some questions it would be him.
I have asked him about it (obviously) a while ago trough PM so I already know the answers to my questions.
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My corner line arrays might be 2-ways, multiple 4" cones and a single Fountek Neo 5i or 3.5H at ear height... Array enclosure divided in cells of 3-4 stacked woofers. Products_Fountek Electronics Co.,Ltd
Juhazi, something like that has been tried before. I tried an expanding array myself:
http://www.diyaudio.com/forums/multi-way/258246-corner-expanding-line-array-kef-q100.html
Your problem will be C-to-C distance at the crossover. You could try to roll off each outer element progressively lower in frequency. That would be similar to the expanding array. In fact, that is exactly an expanding array. If you don't roll off the outer elements, the C-to-C distance between the outer elements and your tweeter will be too large at the crossover point. I tried to get around the C-to-C problem by using a coaxial driver.
All these problems just go away with an array composed of identical elements radiating the entire frequency range. You don't want these elements to be too big. If your element was 7 inches instead of 3.5 inches, I'd guess that comb filtering would start one octave lower. Also, you'd get tremendous beaming. If you keep the element size relatively small, it all works out. That is where the TC9 driver really shines. It has a smooth response to begin with, a well-designed motor, uniform off-axis response (see Art's measurement earlier) and is cheap to boot. What else can you ask for?
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I am puzzled why everyone is so worried about ...WWWWWTWWWWWW.... lobing but not FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF... lobing!
I´d like to see some real world measurements of the first like ra7 showed of his CLA.
And here is his line at 6ft unsmoothed 7ms IRgate (like we look at 2/3ways integration/lobing) I am puzzled about that 1,3kHz dip, that should be pretty audible and it lies at a very sensitive range...
I´d like to see some real world measurements of the first like ra7 showed of his CLA.
And here is his line at 6ft unsmoothed 7ms IRgate (like we look at 2/3ways integration/lobing) I am puzzled about that 1,3kHz dip, that should be pretty audible and it lies at a very sensitive range...
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Well I'm not worried. But I wouldn't call your proposal a floor to ceiling array either in the same sense ours is. Obviously you're free to try. I did warn you about missing out on the advantages of that floor to ceiling line array though. But You'll never know what you'd be missing anyway unless you tried them. Many people told me I was a fool to try and build my arrays. I surely didn't listen to them.
Now why would you look at plots of a raw measurement of an array at 6 feet if the proposed listening distance is double that and EQ is part of what makes them work?
You'd miss all the integration that the line array has to offer at the right listening distance and to judge it I wouldn't run it without the needed EQ.
This isn't a 2/3 way in any sense and generally speaking you don't measure them up close. Forget about that multi way view for a moment. This is an entirely different animal. With that difference there also comes in a different set of rules on how you should deal with that animal. You can't compare it to that 2 or 3 way and measure up close to decide on certain things. That's heading for a disaster.
Just to be save I just viewed an unsmoothed but corrected frequency response IRgated 7 ms at the proposed listening distance and this shows me no such dips at all.
Now if I were building a 2 or 3 way with the experience I have building the arrays I'd do it a bit different than what you propose as standard practice. But that's an entirely different discussion that I won't start here.
I looked at my left and right speakers and neither of them show any such dips. I'm sure by the time ra7 finishes his processing we could come back to this point and prove it. But for obvious reasons at the listening distance.
Many people told me I was a fool to try and build my arrays. I surely didn't listen to them.Now why would you look at plots of a raw measurement of an array at 6 feet if the proposed listening distance is double that and EQ is part of what makes them work?
You'd miss all the integration that the line array has to offer at the right listening distance and to judge it I wouldn't run it without the needed EQ.
This isn't a 2/3 way in any sense and generally speaking you don't measure them up close. Forget about that multi way view for a moment. This is an entirely different animal. With that difference there also comes in a different set of rules on how you should deal with that animal. You can't compare it to that 2 or 3 way and measure up close to decide on certain things. That's heading for a disaster.
Just to be save I just viewed an unsmoothed but corrected frequency response IRgated 7 ms at the proposed listening distance and this shows me no such dips at all.
Now if I were building a 2 or 3 way with the experience I have building the arrays I'd do it a bit different than what you propose as standard practice. But that's an entirely different discussion that I won't start here.
I looked at my left and right speakers and neither of them show any such dips. I'm sure by the time ra7 finishes his processing we could come back to this point and prove it. But for obvious reasons at the listening distance.
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No, I wouldn't trust my ears. I do trust my plots, many of them. But like I said, different discussion. Now why do you think you should be away from the array at certain distance to fully enjoy what they do well? I bet you could answer that question yourself.
I invite you to read my thread (preferably all of it), no need to agree with me or my points of view: http://www.diyaudio.com/forums/full-range/242171-making-two-towers-25-driver-full-range-line-array.html
But viewing that tread you will learn that I did measure, and measure some more. And published everything for all to see. Except for the measurement files. You've just shown why I decided to do it that way.
One of the latest plots in my thread was done with APL_TDA, demo version. Just to see a high res wavelet, here it is:
I do want to tell you even though this result was at the listening distance with floor to ceiling arrays using the TC9, they weren't technically corner arrays. I have high hopes for ra7's arrays, as I'll be helping him get the processing right. You're looking into the measurements trying to show something they weren't made for. That's reason enough for me not to publicly post my REW measurements. But I do post plots, many of them. I might even win the competition of posting the most plots ever in one thread, should there be such a competition.
While floor and ceiling reflections are absent, other reflecting surfaces still count. There are all sorts of reflecting surfaces in my room. At 12 ft, I'm reasonably close to the opposite side wall, so that could be a reflection from the sidewall. The point of the measurements was not to look at gated HF frequency response, but to understand the vertical performance and the change in response with distance. The measurements should be looked at in that context. I can show you the corrected absolute response at the listening position. It is quite smooth. But I'll also tell you that I am trying to find sources of certain reflections and eliminate them with Wesayso's help.