We better ask Oliver, LineArray, the diyaudio Golomb ruler sparse line array specialist ! I got the idea for sparse on wall line array from him.
Beveridge was the inspiration of the placement.
The purpose of such an array, as I said, is to mimic the stereolithic side wall reflections with real sound sources.
- Elias
Hey, whatever makes it sound more real and more enjoyable sounding seems best for the home. Anything that effectively undoes the damage of interaural crosstalk, listening room acoustics, and microphone idiosyncracies relative to how the two ears hear, etc. makes sense enough to me. If you're talking recording studio and mixing room, then perhaps an anechoic chamber should be considered one of the places to mix for since every listening room will have a hard to predict and different set of problems (?).
Then I suggest you second time to DIY some dipole line arrays !To at least have a reference what you'll be missing with the flooder approach. I don't claim you will like them or that better, but to know more about what is possible.
I like the Analysis Audio speakers for their speed and directness, but concerning imaging they are far away from being a serious option. Maybe if one plastered the wall behind them with 100 mm Basotect, but not in an untreated room.
Hi Elias,
i proposed you to experiment with such a configuration
like (the 3 upper drivers) in dipol 08, because you were
complaining about being able to localize the tweeters
in most designs.
The "real" HF source in that design is pretty virtual.
When first designing it, creating HF diffusivity was not my
intention, i wanted something like an array adapting height
in relation to wavelength radiated.
I initially planned to reduce the array to a single driver in the
highs, but it turned out that it worked pretty well only reducing
it to the upper 3 drivers, which also simplified the crossover design.
Many asked "why didn't you make it focussed" as it is obvious
that phase is messed up above say 2Khz.
But as was pointed out here in some posts, that absolute phase
information is not important above 2Khz to get proper imageing.
Of course group delay has to stay within sane limits.
But even when phase is somewhat "random" at HF i would not
regard that "dipol 08" a diffuse radiator.
i proposed you to experiment with such a configuration
like (the 3 upper drivers) in dipol 08, because you were
complaining about being able to localize the tweeters
in most designs.
The "real" HF source in that design is pretty virtual.
When first designing it, creating HF diffusivity was not my
intention, i wanted something like an array adapting height
in relation to wavelength radiated.
I initially planned to reduce the array to a single driver in the
highs, but it turned out that it worked pretty well only reducing
it to the upper 3 drivers, which also simplified the crossover design.
Many asked "why didn't you make it focussed" as it is obvious
that phase is messed up above say 2Khz.
But as was pointed out here in some posts, that absolute phase
information is not important above 2Khz to get proper imageing.
Of course group delay has to stay within sane limits.
But even when phase is somewhat "random" at HF i would not
regard that "dipol 08" a diffuse radiator.
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Hi Oliver,
in my view the main problem in that AA design is the discontinuity
between the bass panel and the tweeter in radiation pattern.
Two very different radiators (in width !) are blended at about
600Hz with a fairly broad overlap due to 6dB/octave slope.
Additionally that means in whole crossover region phase will be very
dependent from horizontal listening angle. As we heard in this thread,
below say 800Hz phase is very important for imageing.
AA design allows little asymmetry in listening position and wants
the speakers to be toed in quite exactly.
Direct/reflected ratio is very dependent from frequency, room,
setup, listening position.
If aiming for "robust" imageing, i would regard different designs
as being "prudent" ...
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Did you try to listen with all the 6 drivers full range ? And why settle to low pass the 3 lower drivers? Everyone would suggest comb filtering as a reason, but was it really? Any issues with image height?
- Elias
Yes, it works quite well but se below ...
The impression in the Khz region was a bit "faint" or "smeared" and
image height over stretched. Piano attack e.g. was missing "impact".
The lower 3 drivers are not just low pass filtered, they are row circuited
to the 3 upper and bypassed at HF, so the speaker's impedance lowers
and more power is applied to the upper 3 drivers at HF.
This way the speaker does not suffer from the vastly falling power
response at/above brillance region nearly every fullrange (based) system
has. It is that which makes most FR systems easy to identify if you
enter the listening room. Dipol 08 is not itentifyable as FR based system
by listening.
In case all 6 full range, at what listening distance was this issue noticeable? How about at longer distances, like 4++ meters, still got the "smearing"?
- Elias
And again I have to ask how is this going to happen in a Beveridge setup???
An externally hosted image should be here but it was not working when we last tested it.
No ipsilateral reflection but strong contralateral reflection. Stereolith is the other way around. Completely different perception.
Place the Beveridge at the point of first ipsilateral reflection from a Stereolith. Of course it is not identical, but the pattern is the same, only that Stereolith creates wider stage than Beveridge.
- Elias
I've learned a bunch from this thread. I've also learned new reasons why what I believe is true. Reproducing music well is a complicated challenge. It's hard to give someone a simple answer to a complicated question.
Effectively putting the speakers farther apart than the standard 60°? That is a completely different situation when compared to a Stereolith. The reflection pattern is not similar, not even close.
Sounds a bit pricey?
It is not known yet, to me, what is the ideal vertical directivity pattern of a stereolithic projection. I could guess, that some second order ipsilateral reflections from ceiling and floor are beneficial, however this is not confirmed yet? Then if we assume this, vertical directivity should be wide. However, that kind of line source could work if arranged horisontally and aimed sideways towards the first ipsilateral reflection point to prevent direct sound from reaching the listener. Maybe better make a prototype with a cheaper unit first
- Elias
Markus, now you take pen and paper and draw some lines, maybe with the help of a ruler 
sorry guys but not really -
absolutely! this is most important conclusion from the study
correct!
here is my comment:
anatomic transfer function - post #545 in this thread
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