confirming design before construction - ceiling slope?

Hi folks, continuing from the design recommended by John (http://www.johnlsayers.com/phpBB2/viewt ... haped+room), I'd like to confirm that my room design is ok before I proceed to construction matters. The main problem I see is that both my head (ears at 1.27m sitting down) and the LF drivers are very close to the vertical half way. My fix is to put in a sloping ceiling starting on the soffit face such that the LF driver is at 3/5 soffit height and going up towards the back of the room. This also puts my ears at about 3/5 (of a bigger dimension though) in the listening positioning. Is that ok or do I need to alter the ceiling slope to mix that up a little? (I've seen 3/5 and 46% recommeded). One thing I considered was putting the speakers upside down - then the woofers ar kinda high....does that matter? but it doesn't solve the listening position problem. thanks in advance, Mike

refer to your speaker manuals about proper listening position for isntance, the behringer truth monitor manual says that for optimum listening position, the listener must have the tweeters at ear level also, i've heard that ceilings are supposed to slope back, the lowest end being at the speaker side of the control room (the front), and the highest being towards the back end but i am no expert, and could be incorrect.

Ceilings do indeed want to slope UP to the REAR, but speakers don't have to be so their tweeters are exactly at ear height - within reason, you can elevate speakers and then tilt them so the tweets still aim at your ears when at the desk. Some reasons NOT to go very far afield with this - if you have others listening at the rear of the room, too much tilt may cause a loss of high frequencies back there. Too much tilt can cause the direct sound to bounce off the desk, mixer, etc, and into your ears causing early reflections. And a third reason - if speakers are more than about a foot higher than the ears, especially in a small room, the angle becomes steep enough that your ears don't hear high frequencies the same as if they arrive in a level plane - this is due to the shape of the Pinnae, or the outer, visible part of the ear. Its shape is meant to give directional ability so you know where the danger is coming from (presumably so you can run the OTHER way :wink: ) - So, as a result you will likely mix too bright if your speakers are too far off axis vertically. In the Acoustics forum there is a topic, "are my speakers in a null", that should help you - go here http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2441 download the harmon spreadsheet I linked to, and set one of the dimensions to 100 feet 0" - that will show you peaks and nulls in percent of total dimension, which you can convert to your room height - read the rest of that link and it will help you figure out dimensions that will work for your situation. Your sloping ceiling plan is a good one, BTW - and not just for keeping your speakers/head out of modal problems... Steve

ok, thanks, am getting the hang of how to use the modes spreadsheet. I'll use it to finalise the ceiling height at the speaker and listening position. It would be good visualised in 3d! Thats interesting stuff about the ears, I considered tilting the soffit, but it seemed like a lot of extra work for relatively little benefit. I think the sloping ceiling gives more benefit for the work put in, more bang for the buck so to speak. thx again.

Since that ceiling appears to be fairly low (less than 11 feet) and the volume of the room so small, my inclination (pun intended) would be simply to put as much mineral wool or 703 up there at an angle as fits. In other words, make it look like an angled ceiling, but instead of sheetrock you'd see acoustical cloth. Wouldn't enough mineral wool make the ceiling acoustically disappear for practical purposes? Whaddya think, Steve? Lee

That would sure make my construction life easier :-) I was attempting to get the fundamentals right (pun intended!) ie get the dimensions and angles right. The calculations always (I think) refer to the actual wall boundary, not the edge of acoustic treatment, and my guess is that this is particularly so at LF. So I wonder whether - although you idea absorbs LF - if it isn't better to not have them there in the first place, if you get what I mean. On the other hand I might be being too cautious for my own good and in this environment what you suggest would work fine. :?:

nudge nudge :wink: any other takers? To build a proper ceiling or to use heaps of absorbtion that also slopes up and back? Both? Remembering my goal is a good listening environment, not soundproofing - tho I'm happy to achieve both! - Mike

Insideout: I agree with Jazzman. Absorptive ceiling, with a faux surface. Andre