Moral of story: this is further evidence of the fact that specialized room treatment is often not needed to optimize your speaker and room interaction. Carpeting, drapery, art, furniture (Toole says bookcases make great diffusers) and placement will often do the trick without turning your listening room into something that looks like a speaker testing lab or recording studio.
Yet another diagonal devotee! Thanks for the confirmation Rip. The last two living room/A/V rooms I've done have been in the diagonal configuration. My home set-up was shown as a practical example in CEDIA Seminar 3 article found here:
http://www.audioholics.com/techtips/roomacoustics/roomacoustictreatments2.php
In looking at the pictures the first huge difference one can note (though it doesn't look huge at all) is that my speakers are
aimed inward and downward toward the listening position. Automatically, no left or right first order reflections. And a good proportion of damaging reflections from the ceiling are moved back behind the listening position as explained in the text.
I have today been tinkering with the idea of laying out a tiny 5.1 TV mix studio in my back basement -- on the diagonal. Armed with an excellent report put out by the Recording Arts and Sciences Engineers and Producers Wing on all things having to do with surround mixing and studio design,
In our EMX show report which covered the initial presentation of the report "Recommendations for Surround Sound Production" by The Recording Academy's Producers and Engineers Wing, we said this:
Session: The Recording Academy: Everything You Need to Know About 5.1 Audio Production
Day 2 of Surround 2004 started off with this session. George Massenburg is head of the Producer and Engineering wing of the Recording Academy. For the past three years his group has struggled in putting together "Recommendations for Surround Sound Production". This comprehensive document (found here) is the most extensive document ever published regarding how the recording engineers, producers and the artists themselves have created 5.1 material.
Many points within this document are admittedly not fully agreed upon by all parties. That’s part of the creative process. George and his group focused on getting out this
template of recommendations to serve as a guide to those just entering the recording end of surround sound.
The Recording Academy recommendations differ from THX in that the recording engineers recommend 5 full range speakers set at equal distance from the listening position. Most of the recording engineers agree with the original ITU spacing for the surround speakers which is ±110° from the center channel speaker though a couple very well known guys like Elliot Scheiner (Eagles) and Phil Ramone (Rod Stewart, Elton John, Bob Dylan) prefer 150°.
The listening position would be roughly in the center of a 14 x 15.5 space (7.5' ceiling) with speakers surrounding it (no pun) in an imaginarry 13' circle, with the LF and RF speakers 30 degrees on either side on the center speaker, and the surrounds at 135 degrees left and right, everything at ear level and everything equidistant from the listener (equidistant is a new wrinkle to me, and apparently very important). When considered in a vacuum, this arrangement would work well, but as walls are moved into place -- very close and at odd angles to the speakers (Mackie HR 824's -- which in fact have rear-firing passive radiators) I just wonder... Any sage wisdom -- beyond cleaning out the back basement and dragging some gear in and doing some listening?
For our readers, some of what the The Recording academy's report states on the summary page
-" No two room dimensions should be equal. The ceiling height ideally should be greater than 11 feet."
-"The optimum speaker distance from the mix position is between 6.5 and 7.5 feet"
One of the acoustic reasons for recommending an 11 foot ceiling is that it will put a seated engineer at about the optimal 1/3 the distance from floor to ceiling. A 7.5" ceiling on the other hand will locate your head almost in the center of the 7.5" height. Beware of potential nulls at 150Hz and 300Hz. Could really mess with your vocals.
Next 14', 15.5' and 7.5' are all really close harmonically so you're likely to experience several other areas of cancellations. You might want to model your room with any of the freely available room mode calculators as found on sites like
www.harman.com. Bear in mind though that all these calculators are for an ideal sealed retangular box. Put a door into the equation and the results, especially in a room so small, can very substantially.
Lastly, your 13' circle will now put your Mackie's right next to room boundaries. And since all speakers will go down well below 100Hz (a lot of piston area in different locations) your room will have standing waves generated by 5 speakers at the same time! This last point is the reason leading acousticians in the home audio playback community with whom I've spoken disagree (quietly, up to this point) with the five full range speaker set-up proposed in the Recording Academy's recommendations.
I have only worked in one mixing control room that was setup on the diaginal, and it in fact sounded wonderful -- but there must be a reason studio designers tend to avoid this sort of layout...
My only guess as to why mixers haven't used the diagonal set-up would be that most have always worked with a straight-on rectangular layout which is usually laid out with a front window so the musicians can be seen in their own soundproofed environment.
