Hi Stuart;
Thanks for your reply, and I apologize for not getting on top of it sooner. Geez, you get to the end of holidays, and work hits you with both barrels blazing. Haha.
Anyways...
Yes, I do see that (with your very clear images - not from my own analysis of the data) big difference with and without absorption on the desk. Very interesting.
My sub has been shipped (finally), so should arrive any day now.
Now.... since the monitors weren't providing any reflection issues, I'm really thinking of going back to two monitors if I can swing it.
Given your suggestion of: "pull both speakers about 3" or so away from the front wall, towards you, then re-angle the speakers a bit more inwards so they are still pointing correctly (just past your ears, not AT your ears!), and also raise them about an inch or a bit less (put a book under each one for now, just for testing.) Do a REW test like that for both speakers, and post it here."
Should I do that with both monitors back in place, or just with the one where it is for now?
Should I do that with absorption on the desk, since that seems to help a lot, or do you want to see what happens without? Or both?
And if the sub arrives tomorrow, should I do it with or without the sub?
Thanks!
Chris
use of a sub in a small room
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axemanchris
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Re: use of a sub in a small room
I would keep the sub out of the picture for now, so we can validly compare what we already have. Adding the sub adds another variable to everything, so it would be impossible to tell if the changes were due to the sub, or to something else.
You should also find that the sound-stage is a bit wider with the monitors moved as above.
- Stuart -
First, do a test with the monitor exactly like it is now, WITH the absorption, then one WITHOUT the absorption, then replace the monitors and repeat: one test WITH absorption, one without.Should I do that with both monitors back in place, or just with the one where it is for now? Should I do that with absorption on the desk, since that seems to help a lot, or do you want to see what happens without? Or both?
You should also find that the sound-stage is a bit wider with the monitors moved as above.
- Stuart -
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axemanchris
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Re: use of a sub in a small room
Hey there!
Sorry it took me a few days. Busy weekend with back to work, my wife's birthday, etc.
Anyways... here is the file:
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I've labeled the "takes" for (hopefully) easy navigation, along with comments in the boxes.
O = original position from last time
L = Left Speaker
R = Right Speaker
B = both speakers
M = mat on desk
3 = moved speakers about 3 inches out from wall and added a 3/4" book underneath.
W = speakers widened to make way for addition of second computer screen.
Here's something I just thought of too....
I'm using a Behringer ECM8000 mic. It's very omnidirectional, and has a very flat frequency response. However.... I've been pointing the mic straight up to measure the room. Should I, instead, point the mic straight ahead between the speakers to measure the signal coming from the speakers? I'm not sure what the off-axis response is on that mic.
Thanks for whatever you can offer!
Chris
PS. Sub arrived.
Sorry it took me a few days. Busy weekend with back to work, my wife's birthday, etc.
Anyways... here is the file:
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I've labeled the "takes" for (hopefully) easy navigation, along with comments in the boxes.
O = original position from last time
L = Left Speaker
R = Right Speaker
B = both speakers
M = mat on desk
3 = moved speakers about 3 inches out from wall and added a 3/4" book underneath.
W = speakers widened to make way for addition of second computer screen.
Here's something I just thought of too....
I'm using a Behringer ECM8000 mic. It's very omnidirectional, and has a very flat frequency response. However.... I've been pointing the mic straight up to measure the room. Should I, instead, point the mic straight ahead between the speakers to measure the signal coming from the speakers? I'm not sure what the off-axis response is on that mic.
Thanks for whatever you can offer!
Chris
PS. Sub arrived.
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axemanchris
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Re: use of a sub in a small room
Interesting....
Just for my own curiosity, I tried measuring my current setup (both computer screens back in, requiring the speakers to be moved outwards a few inches on each side, with the speakers back in their original positions. (no mat on my desk to dampen reflections)
I ran a REW test with the mic (ECM8000) pointing basically straight up (as I have been doing), and one with the mic facing forward, basically toward the "seam" between the two computer monitors.
I'm not too sure what to make of the significance here. Sure, the big problems are still big problems. Those didn't go away. But some of the differences were surprising..... though didn't really seem to resemble either an improvement or a step backwards. Just.... surprising differences. Where there was a valley is now a spike, etc.
Here is the REW file if anyone is interested in digging deeper:
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I mean, sure... it's no mystery that *any* mic behaves differently comparing its on-axis to its off-axis response. But the ECM8000 is a very omni mic. The polar response graph is pretty impressive.
http://atozaudio.s3.amazonaws.com/prd/9 ... _Graph.jpg
Chris
Just for my own curiosity, I tried measuring my current setup (both computer screens back in, requiring the speakers to be moved outwards a few inches on each side, with the speakers back in their original positions. (no mat on my desk to dampen reflections)
I ran a REW test with the mic (ECM8000) pointing basically straight up (as I have been doing), and one with the mic facing forward, basically toward the "seam" between the two computer monitors.
I'm not too sure what to make of the significance here. Sure, the big problems are still big problems. Those didn't go away. But some of the differences were surprising..... though didn't really seem to resemble either an improvement or a step backwards. Just.... surprising differences. Where there was a valley is now a spike, etc.
Here is the REW file if anyone is interested in digging deeper:
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I mean, sure... it's no mystery that *any* mic behaves differently comparing its on-axis to its off-axis response. But the ECM8000 is a very omni mic. The polar response graph is pretty impressive.
http://atozaudio.s3.amazonaws.com/prd/9 ... _Graph.jpg
Chris
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Soundman2020
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Re: use of a sub in a small room
Thanks Chris! That's interesting, but before I comment: are you sure you had the TIP of the mic in the exact same place in the room? Or did you just tilt the mic down then measure? The reason I ask is because it is critical that all tests must be performed with the mic tip in the exact same location in the room, always the precise same distance from the walls, floor and ceiling. If you just tilted the clip down, then the mic is not only facing a different direction, but is now also several cm lower than it was, and several cm further forward...
Maybe you could do a set of three tests, carefully repositioning the mic tip as accurately as possible: one with the mic pointing up, one pointing forwards, and one pointing diagonally up at about 45° (if you REALLY want to get fancy, do two more tests, at 30° and 60° tilt).
- Stuart -
Maybe you could do a set of three tests, carefully repositioning the mic tip as accurately as possible: one with the mic pointing up, one pointing forwards, and one pointing diagonally up at about 45° (if you REALLY want to get fancy, do two more tests, at 30° and 60° tilt).
- Stuart -
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axemanchris
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Re: use of a sub in a small room
Okay.... here is what I got from that. I measured at 10 degrees (the clip doesn't allow the mic to point straight up exactly), 90 degrees (completely horizontal), 45 degrees and 60 degrees.
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
A couple interesting notes:
1) with the mic pointing almost straight up at 10 degrees, there is a big dip between roughly 9k and 15k that is not there at any of the other angles.
2) a lot of the deeper dips seem to be more moderate with the mic pointed 45 degrees, but as a rule, not as much at 90 degrees (using 10 deg as the point of comparison)
For my method, I taped a string to my cloud and marked the position of either end of the tape with two smaller pieces of tape. I taped a pencil to the string so it pointed downwards towards the tip of the mic and hung 1/4" above the capsule. I measured the height of the tip of the mic at 47".
In the interest of avoiding reflections off the pencil - especially being so close to the mic - I took the pencil down before measuring.
To replace the pencil for the next measurement, I taped it back up - exactly between the two smaller pieces of tape stuck to the cloud to mark the original position - and placed the tip of the mic 1/4" below the tip of the pencil, ensuring it was again 47" from the floor.
lather.... rinse.... repeat.
Chris
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
A couple interesting notes:
1) with the mic pointing almost straight up at 10 degrees, there is a big dip between roughly 9k and 15k that is not there at any of the other angles.
2) a lot of the deeper dips seem to be more moderate with the mic pointed 45 degrees, but as a rule, not as much at 90 degrees (using 10 deg as the point of comparison)
For my method, I taped a string to my cloud and marked the position of either end of the tape with two smaller pieces of tape. I taped a pencil to the string so it pointed downwards towards the tip of the mic and hung 1/4" above the capsule. I measured the height of the tip of the mic at 47".
In the interest of avoiding reflections off the pencil - especially being so close to the mic - I took the pencil down before measuring.
To replace the pencil for the next measurement, I taped it back up - exactly between the two smaller pieces of tape stuck to the cloud to mark the original position - and placed the tip of the mic 1/4" below the tip of the pencil, ensuring it was again 47" from the floor.
lather.... rinse.... repeat.
Chris
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Re: use of a sub in a small room
Hey there! I have a few hundred dollars saved up for treating my room a little further. I'm looking at bass trapping in some way, despite the limitations of both the size and layout of my space.
My front corners (I think that's right.... the corners that I see while I sit facing forward in the mix position), I'm gathering, are more important to treat than the back corners. Is that right?
The corner to my left goes floor to ceiling - about 6'8". I have 22" along the side wall before anything would interfere with the fruit cellar door (which is decidedly inaccessible anyways, but.... ). Along the front wall, I only have 9.5" before it would interfere with the absorber behind my monitor. That could be pushed inwards about 8" or so towards the center panel (all of this visible in the very first picture in the very first post of this thread). So, I could get a maximum of about 18" in that corner by moving that one panel.
The corner to my right is much more complicated. I've only got 9" before anything would interfere with the closet door on the side wall. I can't fudge it by making the closet narrower as it is already only 24" wide. Along the back wall, I also have about 9" between the corner and the right absorber behind the other monitor. Again, in the interest of symmetry, it might be advisable to move that inwards anyways to match the other one if if moves. The other complication is that I only have 58" from the floor until the window interferes with things. I'd rather not cover the window if I can avoid it.
Does a bass trap have to be an isosceles triangle with angles 45, 90, 45? Would a bass trap that was, say, 9" x 18" with a hypotenuse of about 20.25" be helpful?
Along that same front wall, if I placed bass traps horizontally (The room is 8' wide), it looks like this:
Floor:
See diagram. If I broke the bass trap up into three pieces - one under the desk, and one on each side of the desk - I again am stuck with only 10" I could squeeze a little more, but that gets us into territory of moving the speakers outwards. I'm not sure if that's a good idea or not. Even then... I don't want to push my mix position back too much farther, than it is, because it's not far from where I am to the dead center of the room. (currently, my ears are about 30" away from each speaker and about 38-40" from the wall... or 33-35% mark. The dead center of the room would be the 57" mark.) I could go much further UP the wall... just not out.
Ceiling:
The window is the real obstacle here. See diagram. Here is the corner:
http://www.johnlsayers.com/phpBB2/downl ... p?id=41908
The closet goes almost to the ceiling. It is only about 7" shy of it.
The other horizontal corners along the ceiling are just as difficult - useful space of only 4", 6", 7" pretty well all around. The wall behind me is pretty much as unforgiving too for corners.
Pic before treatment: http://www.johnlsayers.com/phpBB2/downl ... p?id=41309
with absorbers: http://www.johnlsayers.com/phpBB2/downl ... p?id=41910
Any thoughts?
Thanks!
Chris
My front corners (I think that's right.... the corners that I see while I sit facing forward in the mix position), I'm gathering, are more important to treat than the back corners. Is that right?
The corner to my left goes floor to ceiling - about 6'8". I have 22" along the side wall before anything would interfere with the fruit cellar door (which is decidedly inaccessible anyways, but.... ). Along the front wall, I only have 9.5" before it would interfere with the absorber behind my monitor. That could be pushed inwards about 8" or so towards the center panel (all of this visible in the very first picture in the very first post of this thread). So, I could get a maximum of about 18" in that corner by moving that one panel.
The corner to my right is much more complicated. I've only got 9" before anything would interfere with the closet door on the side wall. I can't fudge it by making the closet narrower as it is already only 24" wide. Along the back wall, I also have about 9" between the corner and the right absorber behind the other monitor. Again, in the interest of symmetry, it might be advisable to move that inwards anyways to match the other one if if moves. The other complication is that I only have 58" from the floor until the window interferes with things. I'd rather not cover the window if I can avoid it.
Does a bass trap have to be an isosceles triangle with angles 45, 90, 45? Would a bass trap that was, say, 9" x 18" with a hypotenuse of about 20.25" be helpful?
Along that same front wall, if I placed bass traps horizontally (The room is 8' wide), it looks like this:
Floor:
See diagram. If I broke the bass trap up into three pieces - one under the desk, and one on each side of the desk - I again am stuck with only 10" I could squeeze a little more, but that gets us into territory of moving the speakers outwards. I'm not sure if that's a good idea or not. Even then... I don't want to push my mix position back too much farther, than it is, because it's not far from where I am to the dead center of the room. (currently, my ears are about 30" away from each speaker and about 38-40" from the wall... or 33-35% mark. The dead center of the room would be the 57" mark.) I could go much further UP the wall... just not out.
Ceiling:
The window is the real obstacle here. See diagram. Here is the corner:
http://www.johnlsayers.com/phpBB2/downl ... p?id=41908
The closet goes almost to the ceiling. It is only about 7" shy of it.
The other horizontal corners along the ceiling are just as difficult - useful space of only 4", 6", 7" pretty well all around. The wall behind me is pretty much as unforgiving too for corners.
Pic before treatment: http://www.johnlsayers.com/phpBB2/downl ... p?id=41309
with absorbers: http://www.johnlsayers.com/phpBB2/downl ... p?id=41910
Any thoughts?
Thanks!
Chris
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axemanchris
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Re: use of a sub in a small room
^ Not sure why that post above allowed me to post as guest, but it is me.
??
The diagram referred to is here:
https://docs.google.com/drawings/d/1O1B ... sp=sharing
CT
??
The diagram referred to is here:
https://docs.google.com/drawings/d/1O1B ... sp=sharing
CT
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Soundman2020
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Re: use of a sub in a small room
Correct!My front corners (I think that's right.... the corners that I see while I sit facing forward in the mix position),
All corners are good for bass trapping. There are 2 corners in a normal rectangular room, and the are all good candidates for bass trapping. Since front corners are often used for soffited speakers, it's normally the rear corners that get the first bass treatment.My front corners ... I'm gathering, are more important to treat than the back corners. Is that right?
Nope! It can be any shape you want. The deeper the better, and the bigger the better, but shape isn't that important.Does a bass trap have to be an isosceles triangle with angles 45, 90, 45?
Yes, it would be reasonably effective. A really good bass trap is 36" on the hypotenuse, a decently good one is 24", and you are not too far from that.Would a bass trap that was, say, 9" x 18" with a hypotenuse of about 20.25" be helpful?
Yeah, there was a configuration error in the forum software that took me a while to track down, and it allowed members to post as guests when it shouldn't have. But it seems to be fixed now.Not sure why that post above allowed me to post as guest, but it is me.
- Stuart -
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axemanchris
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Re: use of a sub in a small room
Hey there!
Well, I know I shouldn't be surprised, but it more or less seems like I have made more trade-offs than actual improvements.
Here is the mdat file. The data is basic, but represents source from both speakers:
a) before adding the sub, and before adding any bass trapping
b) after the sub and after the bass trapping.
Both represent a little bit of moving speakers forward and back, in and out, to find the best balance of trade-offs.
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I built two bass traps on the front wall behind my speakers. One, from floor to ceiling, about 80". The other from floor to window, about 56".
They were made by filling the corners with 90-degree triangles 8" deep by 24" wide of Roxul Safe and Sound, and then covering them with vapour barrier (6 mil) and speaker cloth.
Here is a photo album that shows what I did, should that be relevant: https://plus.google.com/photos/10515147 ... 8aqgrZKZDQ
I moved some of my acoustic panels around. I now have a 24"x24" and an 18"x24" panel at the front between the two bass traps.
Behind me, I now have one panel 24"x24", one 12"x12", one 18"x24" and one 12"x24". I moved another panel onto the floor to fill up a horizontal corner behind me and to my left. It is 24"x12". All told, I've not removed any panels - just moved some around a bit and added two fairly large (for a room my size) traps representing about 2/3 of a bale of Safe and Sound. I've moved my speakers a little farther back (closer to the traps) and about 6" outwards on either side. This gave me better results (though very slightly, more like just some trade-offs that were a little easier to live with) than leaving them where they were.
I'd figure that the difference would be more significant.
Any thoughts?
Thanks!
Chris
Well, I know I shouldn't be surprised, but it more or less seems like I have made more trade-offs than actual improvements.
Here is the mdat file. The data is basic, but represents source from both speakers:
a) before adding the sub, and before adding any bass trapping
b) after the sub and after the bass trapping.
Both represent a little bit of moving speakers forward and back, in and out, to find the best balance of trade-offs.
https://drive.google.com/file/d/0BwMDmd ... sp=sharing
I built two bass traps on the front wall behind my speakers. One, from floor to ceiling, about 80". The other from floor to window, about 56".
They were made by filling the corners with 90-degree triangles 8" deep by 24" wide of Roxul Safe and Sound, and then covering them with vapour barrier (6 mil) and speaker cloth.
Here is a photo album that shows what I did, should that be relevant: https://plus.google.com/photos/10515147 ... 8aqgrZKZDQ
I moved some of my acoustic panels around. I now have a 24"x24" and an 18"x24" panel at the front between the two bass traps.
Behind me, I now have one panel 24"x24", one 12"x12", one 18"x24" and one 12"x24". I moved another panel onto the floor to fill up a horizontal corner behind me and to my left. It is 24"x12". All told, I've not removed any panels - just moved some around a bit and added two fairly large (for a room my size) traps representing about 2/3 of a bale of Safe and Sound. I've moved my speakers a little farther back (closer to the traps) and about 6" outwards on either side. This gave me better results (though very slightly, more like just some trade-offs that were a little easier to live with) than leaving them where they were.
I'd figure that the difference would be more significant.
Any thoughts?
Thanks!
Chris