Greetings.
I've been reading lots of threats here, and started designing a small control room, but when it comes to placing "my head" I know that i have to be around the 38 % of the room length, And did this, Then I was desiding if using 30 degree soffits or 90 degree. But then I came across this image John bosted time ago:
I noticed that the place where the head is regarding the intersection between the "direct" radiation of the speakers, is different in each case, I tryed to emulate this in my design and came with this design (I'm using 30 degree soffits)
Please Ignore The back side of the room and other designing issues for the moment, I'm JUST talking about the "speaker coverage angle" and if My head and ears are placed correctly.
also ignore the desk if you think it's in front of the speakers or something.
Thanks
you can see in the 30 (60) degree one, there is more space on either side of the head (because the focus point is behind the head) so the "sweet spot" is somewhat more forgiving. however in the right situation, the 45 (90) degree angles could be correct (like a very wide and shallow control room). in some cases, the 30 or 45 degrees might not be correct. sometimes 15 degrees is right, or 22.5 degrees etc.
in your room, maybe 34 degrees is right. some of it is decided by your monitors, some by your working habits. if you have two people sitting at your console, the 30 degrees might be best to widen the sweet spot and keep the couch in play somewhat. maybe you need the sharper focus by having the speaker @ 37.5 degrees on-axis because they have a narrow dispersion or that's how you like to hear it. 30 degrees, like 38%, is a starting point, not the necessarily the end point...
quick question about the 38% rule of thumb, Is is preferable to be more towards 37% or 39%? I remember seeing some graphics of this but can't find them.
It doesn't really matter. I wouldn't be worrying about single percentage points. The 38% "rule" is only a guideline anyway. If you think about it, 1% is less than 3cm in your room: you easily move your head that much just to scratch your nose, or pick up your pencil! It really isn't a big deal: 38% is the theoretical best compromise, taking into account all axial modes for the lowest frequencies, so if you move back 3cm then you will place your ears in a slightly different set of modal nulls and peaks, while moving your head forwards 3 cm will place your ears in yet another set of modal peaks and nulls. But wherever you put your ears, they will ALWAYS be in one set of peaks/nulls. 38% is just a reasonably good compromise, but it isn't written in stone, either! If you have to be at 41% or 35% in order to make your room geometry work out comfortably, then so be it. As long as you are not getting close to 50% or 25%, then you are doing fine. Don't forget that your head is already on the center-line, left-to-right, and probably really close to the center-line, up-and-down, yet you can still hear quite well, despite that. Nobody ever seems to mention those facts when sweating about how to hit the 38% spot exactly.
In any event, most engineers lean forwards and backwards by many cm while they are working, getting their ears way off the 38% point, so even if you bolt your chair to the floor and chain the engineer to the chair, his ears will STILL not be in the exact 38% location all the time.
It's just a guideline, a starting point.
- Stuart -
haha thanks for the detailed explanation, I wasn't referring to that 1% specifically. Just wanted to know if it would be worse to be more to the front or more to the back, but you already mentioned it with trying not to be in the 25% or 50% area.
I Know That nothing of this is written in stone, It is probably my not that good English that make it seem as i would think it is written in stone.
Thanks for the answer, with every line I read I learn something new.
haha thanks for the detailed explanation, I wasn't referring to that 1% specifically. Just wanted to know if it would be worse to be more to the front or more to the back, but you already mentioned it with trying not to be in the 25% or 50% area.
Think of the 38 as 3/8 rounded off. 3/7 and 4/7 have also recommended. It is to avoid the trouble spots, as you wrote.
Thanks for the answer, with every line I read I learn something new.