Downwards soffit angle

Hello everyone, I’m having a bit of a problem with the soffit angle (downwards). After Avare mentioned a 7 degree maximum angle here:http://www.johnlsayers.com/phpBB2/viewtopic.php?f=1&t=11122&start=45 I started more or less designing the soffits all over. (not even close to building yet, so that’s no problem;) As you can see in the attached diagrams, both the 7 and 10 degree angle, are not the best option as far blocking the direct sound by the computer monitor is concerned. And, even worst, the 7 degree option leaves the monitors almost exactly in the middle (height) of the room! So before I fully dive into designing again, I´d like to know the exact ins and outs of the maximum angle downwards. And what are the consequences to be expected, if the angle exceeds the adviced maximum. I´m asking this, not to question Avare´s knowledge or input, which is truly appreciated, but to get as many expert opinions as possible before I make a decision. Thanks in advance, Phybeau

Hi Phybeau! Looks like you and I have the same problem! That's my thread you are referencing, and I'm still trying to to get everything to line up properly... Did you actually measure the height of your own head while seated normally in the exact chair you are planning to use? 110 cm seems a bit low. The usual reference height is 120 cm. Maybe you could raise the chair a bit? Perhaps think about a footrest if that would put your feet off the floor? Just some ideas... You could try dropping the height of your desk a bit, too, or using shorter monitors, or taking the stands off the monitors and mounting them a bit lower down, directly on the wall. These are all things I'm considering in optimizing my design. The only reason I've seen mentioned regarding the 10 degree angle is that the human ear has some kind of issue with accurately identifying the direction and source of a sound (ie, "stereo imaging") if the sound comes from more than 10 degrees above horizontal, but that was just a comment on another thread here, with no references. However, it does sound plausible. I'm still looking for verification.

Phybeau wrote:

As you can see in the attached diagrams, both the 7 and 10 degree angle, are not the best option as far blocking the direct sound by the computer monitor is concerned

You are not thinking it through. The speakers are beside the monitor in plan view. :)

Sondman2020 wrote:

The only reason I've seen mentioned regarding the 10 degree angle is that the human ear has some kind of issue with accurately identifying the direction and source of a sound (ie, "stereo imaging") if the sound comes from more than 10 degrees above horizontal, but that was just a comment on another thread here, with no references. However, it does sound plausible. I'm still looking for verification.

Really? I wrote

avare wrote:

The reason for the spec is that the ears frequency response dips in the 5-8 kHz range as sound sources are elevated.

Nothing to do with localization of image. IIRC The effects of the pinnae on response are detailed in Everest's microphone book. Andre

Avare wrote

You are not thinking it through. The speakers are beside the monitor in plan view. :)

Touché :) If I were using only one monitor, I would not have this issue! Maybe one wide screen would be a practical solution indeed. At the moment I'm using two, with a small desktop speaker for mono listening in between. I kinda like that and would like to continue this....if possible. Stuart, you're right about the height of the ears...it's more 120 cm than 110 cm. So back to the drawing board! :oops: Still leaves me wondering though, which is worse: interferance of the direct sound by lcd monitors, or angling down too much and thus perceiving too little 5-8kHz...?? Just for argument sake, I somewhere (I tried to find it again but no results I'm sorry) read that placing the monitors too high, has the opposite effect on perception... High frequencies are perceived louder. It had something to do with evolution: the stoneage man being warned for danger, from dinosaurs etc. that were bigger than 6 feet. This is of course HIGHLY unscientific from my part, especially because I cannot back it up with the article. ......You may disgard this remark completely..... :D Thanks again, Phybeau

Really? I wrote

avare wrote: The reason for the spec is that the ears frequency response dips in the 5-8 kHz range as sound sources are elevated.

Nothing to do with localization of image.

OK. I guess I should have said "the only other comment BESIDES André's". I'm still trying to find that "other comment" but no luck so far...

The effects of the pinnae on response are detailed in Everest's microphone book.

I didn't know he had a microphone book! I have his Master Handbook of Acoustics, and his Critical Listening Skills, but I wasn't aware of the mic book. Sounds like something I should buy! Do you know the full title? - Stuart -

Something nutty just occurred to me: I guess you could just tilt your chair back 30 degrees, lock it in place, and always lie back while mixing, then you could angle your soffits at 40 degrees if you want! :) (Just kidding. Must be something in the water today . . .)

?? even if you had 2 19in monitors, total width 80cm (sorry for the imperial metric jump) I would think your speakers would still be wider than that? How wide is your room? Have you thought of sinking the base and leg of the monitors into the desk and then angle them up a bit. I little like a video editing suite. lil

lilith_envy wrote:

?? even if you had 2 19in monitors, total width 80cm (sorry for the imperial metric jump) I would think your speakers would still be wider than that? How wide is your room? Have you thought of sinking the base and leg of the monitors into the desk and then angle them up a bit. I little like a video editing suite. lil

Great points! I hope they help. Andre

Lil and Andre, You're right, of course, and thanks for the tip :!: Lowering the monitors into the desk a bit, is probably a decent, practical solution. My room is going to be small, or better: not wide. In the front: 235cm.(~7,71 ft?) (The back wall is 391cm. The room is 401cm deep.) So the speaker centers are going to be approx. 135-140cm apart. Phybeau

Sorry Phybeau - Gotta just quickly chime in with........................ Hey Lil - You Da Babe, and, yes I knew you were not of the Male gender! :wink: :wink: Some people just don't take the clues. :wink: X Lou. 8)

Thanks Lou, Always knew you were more sophisticated than the other boys around here :wink:

Yeah, rub it in why doncha! :) :oops: Like some of us don't feel bad enough already... :!:

sorry soundman I've been holding my tounge for I while ...your just the one that copt it! Here's my desk that I'm converting.

Hi everyone, Just thought I'd share. As a clarification of the previous mentioned room dimensions, and to give an idea of what I'm trying to achieve :jammin: In the drawings the speakers are tilted 10 degrees, and 145 cm above the floor. (height of the room is only 244cm (8 ft)) The centre of the speakers are 135cm (~4,4 ft) apart. If I sink the monitors a little into the desk, it should become quite a workable space. :mrgreen: Thanks for looking, regards, Phybeau

You have another option that you might want to try: Move the speakers further apart, and angle them in more, to get a 90 degree intersection angle, instead of 60 degree. That should also improve your stereo imaging, and get the speakers further away from your video monitors. - Stuart -

Thanks Stuart! I quickly drew your suggestion of a 90 degree angle, just to get an impression. There's no interferance by the screens anymore. In the drawing below, the centre of the speakers are 181 cm apart, the distance between the ears and the speakers is 112cm. Of cours I'm losing my equilateral triangle, which is not neccesarely a bad thing. The thing that worries me, are the direct reflections. I've already built the walls with 12 degree angles, and the place where the doors are going to be. If I'm going for the 90 degree option, the speakers are pointing right at both doors...(hard surface, glass involveld) In the previous 'design' both speakers are directed at the bass traps in the back wall. Furthermore, I got used to the idea of sinking the monitors by now. Especially if I'm going to attach them to 'moveable' arms, this could just work allright. (thanks again Lil) :lol: All in all, I don't know,...yet...gonna to sleep on it.... I read you kinda solved the tilt-angle-mystery :wink: ....at least found some more info...congrats! I more or less decided to stay with the 10 degree angle, unless something extremely alarming comes along Thanks, all the best, Phybeau

Stuart, is there a drawing anywhere that shows the 90o listening point angle? Or for that matter, the entire triangle? W

Nevermind, Phybeau posted one while I was posting. W

What about moving the video monitors back? They do not have located on the work desk. The centre speaker is off the listening circle for the LR speakers. You wrote that you use it for mono checking mostly. If you mount it similar to the LR pair then you can use it for an LCR setup etc. Andre

here's a 90 degrees, angled speakers setup - from memory the speakers were angled at 12 degrees http://johnlsayers.com/Pages/Hello_Testing.htm If you have sketchup and you have speakers in your model draw a small circle (1") on the front face of the speaker and pull it out till it reaches the listener like this: all speakers must be a component.

Thanks John, that was really helpful. Appreciate it. W

Thanks for the link, John. Two questions: In the captions you mention a "compression ceiling" a couple of times. What's that, and what does it do? Do I need one in my room?