speaker soffit placement question

So, I'm spending the time in sketchup to start from scratch and redraw everything to scale and with construction details, etc... One thing I've noticed, based on the original design that John did for me is that to get the mix position anywhere under halfway in the room, it seem that I need to set the soffits at 90 instead of 60 - and I also need to move them in toward the middle of the room from the edge by about two feet. (See drawing below) I can't really move them further into the room (toward the mix position) - because there is a door over on the right (from the POV of the picture). How does this affect acoustics if at all?

What are those? John

Sorry, those are the soffits in question (the bottom of the picture is the front of the room). The dotted lines show where the optimal mix position is. In John's original design (find that in this thread viewtopic.php?f=1&t=11551) - the soffits were all the way out in the corners of the front of the room, but to get a proper mix position, I would have to angle the speakers WAY in (>45o each) which is a bad idea. So, I tried going from having the speakers at 30o to 45o - and I still had to push the actual speaker soffit in closer to the middle of the room. This just seems to be a factor of having a wider room to work with - any better ideas than what I drew up?

I would have to angle the speakers WAY in (>45o each) which is a bad idea.

If your listening position is 38% from your front wall, you CAN position your soffits at 90 degrees, it just makes the sweet spot smaller. I am positioning mine at 90, but remember to get it right, it's taken me 10,000 measures to make this triangle within an 8th inch perfect. I'm have no professional experience in this whatsoever, so do a bit more research. It also helped me to chalk line the listening position with the soffit angles in order to determine the angles and length of the two corner walls they will a join to, but check this out - viewtopic.php?f=1&t=66&start=15 Ian

biggator wrote:

Sorry, those are the soffits in question (the bottom of the picture is the front of the room).

Uhm... no, it's not, John's design has the soffits on the north wall as you look at the picture. THAT's your front wall and your window is there to have visual contact with the live room. Still on John's design, the angled frames on the back wall, the one you are refering to are actually corner bass traps or slot resonators.

biggator wrote:

I still had to push the actual speaker soffit in closer to the middle of the room

Well, you shouldn't push the soffits around, they should be placed by themselves according to your room's and speakers' dimensions. My method to determine the position of the soffits for any room is this: 1. Draw a line that crosses the middle of your room lengthwise. 2. Multiply the room's length by 0,38 3. Mark the spot from the front wall across the line up to the number you just calculated. That's your listening position. 4. Mark the spot about 20cm (8") from the listening position across the line to the front wall. That's where you gonna sit. 5. From the listening position, draw a line 30-45 degrees in respect to the original line, that's where the speakers axis should meet. 6. Measure your speakers length and divide it by 2. 7. Draw two parallel lines left and right of and in respect to the "speaker lines", further apart by the number you calculated. That's your speaker cabinets walls. 7. Measure your speakers width. 8. Draw a line 90 degrees away from the point of the speaker wall lines that meet your front wall. 9. Draw a parallel line to that line you just drew, 10cm (4") away from the front wall to compensate for the soffit frame space. That's your speaker cabinet's back wall. 10. Draw a line parallel to the last one, further apart by your speakers width measurement. That's your speaker cabinet's front wall. All you have to do now is draw a symmetrical outer frame of your soffits to include the speaker boxes you just made. See? Placed by themselves alright! :wink: John

Or you always could flip your listening position and make the front of the room on the shorter end, it should be easier getting those degrees down on a smaller wall.

Mark the spot about 20cm (8") from the listening position across the line to the front wall. That's where you gonna sit.

John, how come the sitting position is 8" from the listening? I haven't read this yet, please inform me :D :D ???

Uhm... no, it's not, John's design has the soffits on the north wall as you look at the picture. THAT's your front wall and your window is there to have visual contact with the live room. Still on John's design, the angled frames on the back wall, the one you are refering to are actually corner bass traps or slot resonators.

Here's the thread with John's original design viewtopic.php?f=1&t=7057 That is most definitely the front of the room (maybe John will see this and chime in here) - and while it doesn't HAVE to be, it makes more sense for one reason.. I have some ductwork along that wall that will force me do to an angled ceiling at that end of the room. The ceiling will start at a low point of about 6', rising up to the full height of almost 9' right over the listening position. From an acoustics standpoint, I would think that this would be better at the front of the room rather than the rear. If there's no real issue with having that at the back of the control room, then I could flip it - but in that original thread, John knew about the constraints and drew the room as shown.

NativeLuv17 wrote:

John, how come the sitting position is 8" from the listening? I haven't read this yet, please inform me :D :D ???

Well, the listening position is behind your head, the lines that end on that spot have to cross your ears. It's approximately 20cm (8") behind your head's center, more or less, it depends on how big your head is and how wide your ears are... :P

biggator wrote:

That is most definitely the front of the room

The picture attached is the one JohnS gave you. When you see the "coffin" design of a control room, the front wall is ALWAYS the less wider. The "coffin" design has the advantage of directing first reflexions to the back of the room, where the wider wall is used for absorbtion or diffusion. Trust me on this one. Besides, when you sit on your console, you need to have visual contact with your live room, which in your case is the room on the front right. John gave you a nice design idea to get you started, John

Well, the listening position is behind your head, the lines that end on that spot have to cross your ears. It's approximately 20cm (8") behind your head's center, more or less, it depends on how big your head is and how wide your ears are... :P

So the sitting position isn't extremely important as long as the apex of the listening point matches up with your ears, correct?

Thanks, jlemon - I guess I had it backward.. though, in my case - the direction really doesn't matter.. I can set up the room either way (I haven't started construction yet anyway!).

Besides, when you sit on your console, you need to have visual contact with your live room, which in your case is the room on the front right.

I'm not even going to bother with a window at all - that other room is strictly for drums and guitar amps (while tracking from the control room) and almost entirely for me and some friends.. if I feel like I need visual contact - I'll put in a video monitor/camera on each wall so we can see each other. The window is a lot less important to me than isolation. So - since I had the room backwards.. lets change the question a bit. How much of an issue will it be (if at all) for the control room to be a roughly 8'10" ceiling up until about the midpoint of the room - then sloping down to about a 6' low-point at the BACK of the room? I'll re-draw in sketchup and see if turning the room 180o makes more sense for soffits and seating position. "-)

biggator wrote:

Thanks, jlemon - I guess I had it backward.. though, in my case - the direction really doesn't matter.. I can set up the room either way (I haven't started construction yet anyway!).

Good for you! :thu:

biggator wrote:

I'm not even going to bother with a window at all.

Well, if you build a commercial studio for clients, then a window is a must I'm afraid. It's impressive for the eye and they need to see that you're there for them. If you're building your personal studio, then you don't need to cut another big hole on your wall...

biggator wrote:

How much of an issue will it be (if at all) for the control room to be a roughly 8'10" ceiling up until about the midpoint of the room - then sloping down to about a 6' low-point at the BACK of the room?

You got it backwards again! :) You need to start from 6' low point from the front wall (after the soffits) and gradually rise to 8'10" to the back wall. And don't get me started on why you want to do that... :P

biggator wrote:

I'll re-draw in sketchup and see if turning the room 180o makes more sense for soffits and seating position.

It will... :wink: John

NativeLuv17 wrote:

So the sitting position isn't extremely important as long as the apex of the listening point matches up with your ears, correct?

Look, I'm a practical man. When I imagine sitting on my leather chair in my newly build studio (with my hair still on my head and not grey :roll: ) , I don't see myself chained to that chair so that my head is a bit forward from a red cross on the floor (x marks the spot). I'm gonna lean forward and rest backwards and stand up, whatever. How wide your RFZ is, that makes the difference, not a few inches here and there. So, my answer is, correct... :wink: John

biggator wrote:

How much of an issue will it be (if at all) for the control room to be a roughly 8'10" ceiling up until about the midpoint of the room - then sloping down to about a 6' low-point at the BACK of the room?

You got it backwards again! :) You need to start from 6' low point from the front wall (after the soffits) and gradually rise to 8'10" to the back wall. And don't get me started on why you want to do that... :P [/quote] see.. this is how the whole thing got started with me wanting the front at the other end. Check out this picture from the earlier 'getting down to details' thread. download/file.php?id=26300&mode=view what you're looking at is the 'bottom' of the picture we're discussing - see all that ductwork? That's why that part of the room has to have the sloping ceiling down to about 6'.. that ductwork can't really be moved. Am I making any sense? "-)

jlemon wrote:

NativeLuv17 wrote:

So the sitting position isn't extremely important as long as the apex of the listening point matches up with your ears, correct?

Look, I'm a practical man. When I imagine sitting on my leather chair in my newly build studio (with my hair still on my head and not grey :roll: ) , I don't see myself chained to that chair so that my head is a bit forward from a red cross on the floor (x marks the spot). I'm gonna lean forward and rest backwards and stand up, whatever. How wide your RFZ is, that makes the difference, not a few inches here and there. So, my answer is, correct... :wink: John

Gotcha ! :wink:

biggator wrote:

see all that ductwork? That's why that part of the room has to have the sloping ceiling down to about 6'.. that ductwork can't really be moved.

If you really need to splay your ceiling, your front wall should be the one with all that ductwork, in order for you to cover them and then start rising. If that wall is not the front wall, try to rotate your control room 180 degrees on your design. John

That's what I'm thinking, actually.. maybe changing the whole layout to accommodate the rising ceiling around the ductwork. Hmm... looks like it's back to sketchup for a while...

jlemon wrote:

biggator wrote:

see all that ductwork? That's why that part of the room has to have the sloping ceiling down to about 6'.. that ductwork can't really be moved.

If you really need to splay your ceiling, your front wall should be the one with all that ductwork, in order for you to cover them and then start rising. If that wall is not the front wall, try to rotate your control room 180 degrees on your design. John

What about a soffit trap at the ceiling to enclose the his ductwork, and double it as a corner (ceiling) trap

Like Bassman's ...

Take a look at the picture of the duct work - it would be a HUGE soffit (like 3.5' deep by 2' high), and it would be really hard to build walls around those ducts then re-run them through the soffit. If I get some time today, going to go into sketchup and re-draw the whole thing.. flipped. Anyone know a good trick in sketchup to select a whole room's worth of objects and essentially do a 'mirror'? Rotating it 180o around center won't work - I need to flip it all.

OK - I spent a bunch of time and completely re-drew the entire thing from scratch.. I tried to make sure that it's pretty much exactly to scale (close enough that I should be able to build right from the drawing), flipped the room the right way, included a bit more detail (all leaves of all walls).. But.. I need a hand - I can't get the file under 500k to upload it here.. it's JUST over (about 530k). I've already deleted anything that wasn't critical, not using much for materials, purged all unused entities... any other ideas? There's a lot of polygons because I actually included all the wall-frame construction. Thanks!!

try compressing it with a program like winrar

NativeLuv17 wrote:

try compressing it with a program like winrar

aah, I thought that they wanted them posted uncompressed... ok - it'll zip down tiny.

ok... redrawn design is in a new thread viewtopic.php?f=1&t=11741