Do you have any experience with line arrays and if so, what kind and what are you impressions and comparisons?
Have not tried a line array at home, no. I am thinking about it of course, but the costs are a bit frightening.
I've heard a few, one of them quite good actually. That one is not a true line array though, only in the midrange as the pic below shows:
In room standing wave study favors a dipole line
This was an interesting thread that didn't get the interest it deserved. He is using a unique test signal/ analysis to study room modes where he eventually found that a dipole line has measured advantages up into the midrange.
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http://www.diyaudio.com/forums/multi-way/145876-measured-monopole-dipole-room-responses.html
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Maybe 1 more W22 to change to a vertically symetrical array?
This was an interesting thread that didn't get the interest it deserved. He is using a unique test signal/ analysis to study room modes where he eventually found that a dipole line has measured advantages up into the midrange.
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http://www.diyaudio.com/forums/multi-way/145876-measured-monopole-dipole-room-responses.html
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Maybe 1 more W22 to change to a vertically symetrical array?
Room modes are dominant below 200 Hz or so, so ideally we should have a line array below 200 Hz. I'm almost there... my 21" H-frame subs will be XO'ed at 150 Hz, and I am concidering a full 2,5 meter tall line array with four drivers in it.
It may seem that there is less to gain in modal response using an array in the low mid range, 150 to 500 Hz.
It may seem that there is less to gain in modal response using an array in the low mid range, 150 to 500 Hz.
Overhang at 1k
That used to be the conventional wisdom but Elias has shown us that room overhang can still be quite pronounced beyond 1k and that a dipole is quite good at getting rid of it and a line of dipoles is even better.
StigErik, did you ever hear these norwegian TonArt Etera dipole line arrays? I heard them at a hifishow in Oslo many moons ago and they sounded fantastic driven by a pair of bridged Dynamic Precision DPA1. Not only do they sound good they look terrific too! 
A dipole line array must be pretty ideal if you want to minimize the room's impact to the sound.
A dipole line array must be pretty ideal if you want to minimize the room's impact to the sound.
An externally hosted image should be here but it was not working when we last tested it.
AFAIK there is a big difference between the arrangement of drivers below the Schroeder frequency and above. And I believe it is quite contrary to Stigs view.
While line arrays may be nice for increasing directivity at higher frequencies, they won't do that in the region of distinct room modes. Room modes produce their own directivity. Vertical bass lines for instance will do nothing to get rid of sagittal room modes - the most prominent. You need to distribute your bass drivers in all 3 directions - not one IMHO.
Rudolf
While line arrays may be nice for increasing directivity at higher frequencies, they won't do that in the region of distinct room modes. Room modes produce their own directivity. Vertical bass lines for instance will do nothing to get rid of sagittal room modes - the most prominent. You need to distribute your bass drivers in all 3 directions - not one IMHO.
Rudolf
Hi Rudolf
not sure we can get rid of room modes anyway (others than opening door and windows )?
If I understood right, the preference of the room to "align" any exaltation toward what fits the room is simply "built into".
Very good summary of room mode exaltation on Kreskovky's page - you sure are familiar with...
The longer I listen to dipole bass the more I tend to claim room pressurization is something of an "unnatural" thing. Room modes - not being in the curriculum of HiFi - on the other hand, sound "ok" to my big surprise.
I do not want to initiate a flame war or something - these are just my observations and impressions whenever I do a listen with the very simple 2-way OB Manzanita (simple compared to Stig Erik's design here or my own big one).
They provide an enormous enjoyable and deep bass in my room they simply haven't any right to.
To loose yourself in the bass lines is even easier if the whole thing is hung (cut out bigger than speaker). Its obvious that OB (nude or baffled) also locks to the room modes - but nevertheless I'm drawn in as if kinda "most natural thing"
Michael
not sure we can get rid of room modes anyway (others than opening door and windows )?
If I understood right, the preference of the room to "align" any exaltation toward what fits the room is simply "built into".
Very good summary of room mode exaltation on Kreskovky's page - you sure are familiar with...
The longer I listen to dipole bass the more I tend to claim room pressurization is something of an "unnatural" thing. Room modes - not being in the curriculum of HiFi - on the other hand, sound "ok" to my big surprise.
I do not want to initiate a flame war or something - these are just my observations and impressions whenever I do a listen with the very simple 2-way OB Manzanita (simple compared to Stig Erik's design here or my own big one).
They provide an enormous enjoyable and deep bass in my room they simply haven't any right to.
To loose yourself in the bass lines is even easier if the whole thing is hung (cut out bigger than speaker). Its obvious that OB (nude or baffled) also locks to the room modes - but nevertheless I'm drawn in as if kinda "most natural thing"
Michael
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1 better than 0
Yes, distributing the bass drivers in 3 planes (as long as the ctc spacing can stay within 1 wavelength or so unless in a line) should be better than 1 plane but his measurements show that even distributing in 1 plane is better than a single location and the vertical array allows the concept to be applied to drivers that are playing up much higher into the midrange without too much smearing of the left/right info.
I did a very precise MJK simulation of what the Beyma 21" Nd would be able to offer. It as I said it would fail on a plain baffle. In an H-baffle it would have a lot more performance to do, but would need great EQ. Now Stig-Erik has done double 21" Beymas H-baffle and they are performing. They should do ! But all in all I think that what is revealed is quite in line with my first simulations.
However now there is some questioning of the reults. I suggest you all go to Stig-Erik's place and all demontrate your own significantly better solutions.
/Erling
However now there is some questioning of the reults. I suggest you all go to Stig-Erik's place and all demontrate your own significantly better solutions.
/Erling
Hi,
What's that mean by "it would fail on a plain baffle"? Any size? Why?
Or, is there a clear boundary between "fail" and "perform"?
By the Sd and Xmax of that Beyma 21", I believe I can use it 'naked' with much satisfaction. (Ok, that's for me)
And I feel it's an awful pity that under all the passions on OB among us, few has tried amps with high output impedance, or T-bass circuit, to get a better amp-speaker coupling.
My findings regarding the 21" Beyma is that it cant play below 40 Hz "naked" without severe distortion and noise. The fundamental tone will be lost, all you hear is upper harmonics and wind noise.
In an H-baffle however, things change a lot. In my current H-baffles, 25 Hz is reproduced cleanly up to at least 100 dB SPL, which is very good.
I measured the sensitivity of my H-baffles.... at 100 Hz its a stunning 119 dB / 1 meter / 2.83 V. There is of course some cheating involved, since both 21" drivers are 4 ohm, and driven in parallell (from separate amps). If I was using two 8 ohm drivers, it would still be 116 dB / 1 meter / 2.83 V. That quite amazing I think! The dipole peak is the main explanation for this sky-high sensitivity. The peak is very wide, causing an almost perfect 12 dB/oct roll-off below 100 Hz all the way down to 20 Hz, making EQ very easy.
I have +26 dB of EQ @ 20 Hz, meaning that the sensitivity @ 20 Hz is 93 dB. Not bad!
In an H-baffle however, things change a lot. In my current H-baffles, 25 Hz is reproduced cleanly up to at least 100 dB SPL, which is very good.
I measured the sensitivity of my H-baffles.... at 100 Hz its a stunning 119 dB / 1 meter / 2.83 V.
There is of course some cheating involved, since both 21" drivers are 4 ohm, and driven in parallell (from separate amps). If I was using two 8 ohm drivers, it would still be 116 dB / 1 meter / 2.83 V. That quite amazing I think! The dipole peak is the main explanation for this sky-high sensitivity. The peak is very wide, causing an almost perfect 12 dB/oct roll-off below 100 Hz all the way down to 20 Hz, making EQ very easy.I have +26 dB of EQ @ 20 Hz, meaning that the sensitivity @ 20 Hz is 93 dB. Not bad!
I think Stig-Erik answered very precise.
As parameters are not very optimal for dipole usage, a bit regardless of baffle size. H-loading is a good way of providing air load and helping with low bass performance and really doubling units I think was both necessary and instrumental in achieving desired results. What one can be asking to is if for instance low drum beats are absolutly optimal compared to lower cone weight units. But I think Stig-Erik will be able to answer this.
/Erling
As parameters are not very optimal for dipole usage, a bit regardless of baffle size. H-loading is a good way of providing air load and helping with low bass performance and really doubling units I think was both necessary and instrumental in achieving desired results. What one can be asking to is if for instance low drum beats are absolutly optimal compared to lower cone weight units. But I think Stig-Erik will be able to answer this.
/Erling
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I've never heard orchestral bassdrum, kettle drums and similar instruments reproduced with the same "lightness", attack and lack of what I call "rumble" (you should get the idea..) like those H-baffles I have now. I've never heard the difference between different bass guitars and players like this before either. The same goes for organ 16-foot pedals. They sound like music, not like loud rumble like my old closed box woofers did. In short: its the best bass I've heard from speakers so far.
I want to go a little bit further, so this is what I have in mind right now. Four 21" per side, 2.2 meter tall.
I want to go a little bit further, so this is what I have in mind right now. Four 21" per side, 2.2 meter tall.
An externally hosted image should be here but it was not working when we last tested it.
I'd like to comment a bit on this. I know my room's behaviour very well, all the modes and so on, and I've done a lot of measurements over the years using bass reflex and closed box speakers. All the major modes in all three planes were always visible on measurements.
Now the dipoles came up, and changed everything. The only modes I see on measurements now are the first and second on the length axis of the room, but they are less problematic than before, a lot less. The width and height modes I can not see on frequency response measurents in listeing position. I think that the off-axis nulls of the dipoles have something to do with this. Its also much less bass boom in the rear part of the room, and much less bass in the rest of our house.
Based on this, I'd like to think that dipoles do set off the room modes a lot less than monopolar speakers, even if they are line arrays or not.
Good question indeed.
I dont get the reflected back-wave, as I have a damped front-end in my room. I've listened to dipoles with a live front wall, and I dont like it all too much.
The giant subs are placed almost a meter from the main dipole. I've done measurements to see if there were any major interferance from the subs, but there isnt. I cant hear any negative sideeffects either.
In a room with a reflective front-end it might have been different for all I know.
I dont get the reflected back-wave, as I have a damped front-end in my room. I've listened to dipoles with a live front wall, and I dont like it all too much.
The giant subs are placed almost a meter from the main dipole. I've done measurements to see if there were any major interferance from the subs, but there isnt. I cant hear any negative sideeffects either.
In a room with a reflective front-end it might have been different for all I know.