Speakers that sound great in terrible rooms

The fact that omnis sound good in many "terrible" rooms is imo proof that, in THOSE rooms anyway, the issue was not the room itself.

Duke,

Having a pro in the thread is like cheating. :)

Can we define good though? I mean, I agree with the on/off axis description, but! What about imaging and detail?

How would omnis compare to dispersion limited speakers like big ESL’s, line arrays or horns with narrow beam pattern?  Pro acousticians I've read say that the better the dispersion control is, the less room treatment is required.

The Omni story flies in the face of this, unless we don't care about detail. (Yes, this is devil's advocacy)

Best,

E

@erik_squires wrote: "Duke, Having a pro in the thread is like cheating. :)"

"If you’re not cheating, you’re not trying hard enough." - Gene LeBell (off topic, but he’s the old guy who choked out Steven Seagal. Twice. In the same day.)

Erik: "Can we define good though? I mean, I agree with the on/off axis description, but! What about imaging and detail?

"How would omnis compare to dispersion limited speakers like big ESL’s, line arrays or horns with narrow beam pattern? Pro acousticians I’ve read say that the better the dispersion control is, the less room treatment is required.

"The Omni story flies in the face of this, unless we don’t care about detail."

EXCELLENT points!

Literally EVERYTHING you have said here is why I don’t do omnis myself. (I use constant-directivity waveguide-style horns.)

Experiments with varying the level of spectrally-correct reverberant energy convinced me that there is a "sweet spot" above which the reverberant energy is arguably "too loud" and clarity starts to be degraded. The "sweet spot" level for the reverberant energy is lower than one would normally get from an omni or from a dipole.

The arrival time of our spectrally-correct reverberant energy matters as well, and imo a dipolar or bipolar radiation pattern is generally preferable to an omni pattern because of geometry: The path length for a bounce off the wall behind the speakers is usually longer than the path length for a bounce off the near-side wall. Imo we want to minimize the reflections arriving within the first 10 milliseconds or so (for the sake of clarity and imaging), but then after that spectrally-correct reverberant energy is generally beneficial (for the sake of timbre and envelopment). Credit to Earl Geddes for that 10 millisecond figure. Siegfried Linkwitz says something similar regarding reflection arrival times, though the figure he arrived at is 6 milliseconds.

The approach I use might be called a polydirectional (credit to the late great Richard Shahinian for that term). I use fairly directional main array and then a secondary, similarly directional array aimed up-and-back such that its energy bounces off the wall and then off the ceiling before reaching the listening area, to maximize the time delay without requiring as much distance from the wall as a dipole or bipole would. The level and spectral balance of this secondary array are user-adjustable, so that different room acoustic situation can be adapted to.

Duke

Note that Ohm Walsh are not full but rather pseudo omni (polydirectional?) to manage the reverberative field better in most rooms. The driver is physically attenuated with absorbing material inside the can in the wall facing directions.

@mapman wrote:

"Note that Ohm Walsh are not full but rather pseudo omni (polydirectional?) to manage the reverberative field better in most rooms. The driver is physically attenuated with absorbing material inside the can in the wall facing directions."

Now we are getting into the fine details of a highly evolved speaker design, the Ohm Walsh!

Imo there is at least one very good argument for their choice.

For the sake of brevity (which is NOT my strong suit!) I have been saying that the reverberant sound should have the same spectral balance as the direct sound, but actually it should have a little bit less top-end energy. This better approximates what we would hear in a large venue: Because of the long reflection path lengths in a large venue, the air itself somewhat attenuates the top-end energy in the reverberant sound, relative to the amount of top-end energy in the direct sound.

So I agree with Ohm, and do something similar when "voicing" my own designs.

For a more in-depth discussion, see Robert E. Greene’s article entitled "Records and Reality: How Music Sounds in Concert Halls":

http://www.regonaudio.com/Records%20and%20Reality.html

Duke