#1897450 - 02/24/08 12:58 PM
"warbble" at 1K
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
Offline
|
|
Between 1K and 1.5K (roughly) I hear an odd artifact acoustically. I don't know what it is, except that the sound feels like it's different pressure on one ear as opposed to the other.
I am just a few inches off center in the room on the left/right axis. I am a little more then 38% back from the front wall. I am as close to it as I can be (give or take 6 inches, I could move forward about 6 more inches, but then the speakers would be right up against the back wall absorbers.
I have three 4" thick auralex mineral fiber panels on the front wall, four 6" panels on the two front corners (could not put them on the back corners because of the nature of the room, there is a work space behind me that precludes putting absorbers there), and two 4" thick absorbers on the first reflection points on the side and auralex 1" foam on the roof and in certain places around the room.
I don't know why the 1K range would be out of phase the room is 11.5 feet wide and slightly less than that long. with an 8'9" ceiling.
I know there is a slight boost between 80 and 100 Hz and a null at 105 Hz. but no other frequency range seems out of phase like the 1K range.
pic 1
http://i272.photobucket.com/albums/jj174/hey_mavis/GEDC0230.jpg
pic 2
http://i272.photobucket.com/albums/jj174/hey_mavis/GEDC0222.jpg
Edited by hey_mavis (02/24/08 02:43 PM)
|
|
Top
|
|
|
|
|
#1897708 - 02/24/08 11:29 PM
Re: "warbble" at 1K
[Re: hey_mavis]
|
ricotrex
Senior Member
Registered: 09/26/06
Posts: 32
Loc: Santa Clarita, California
|
|
Offline
|
|
"I have three 4" thick auralex mineral fiber panels on the front wall, four 6" panels on the two front corners (could not put them on the back corners because of the nature of the room, there is a work space behind me that precludes putting absorbers there), and two 4" thick absorbers on the first reflection points on the side"
Mavis,
It's hard to tell from your pictures, but are your front wall and side wall panels flush mounted or did you put an air gap between them and the wall? I had a similar problem in my room to what you are experiencing. I found that moving my panels away from the walls helped dramatically. That 1k, out of phase thing, seemed to clear up. My panels are hung from the walls using inexpensive, unobtrusive picture style wall hangers. To create my air gap, I used pieces of cardboard cut, folded, and taped into squares that act as spacers to lift them away from the walls. Just place them between the panel and the wall! It looks like your pannels are sitiing on shelves. Try to move them away from the wall by a minimum distance of the thickness of the panels. For example, your front wall and first reflection panels are 4" thick, so move them at least 4" away from the surface of the walls they're on. Try it! I think it will help a lot!
|
|
Top
|
|
|
|
|
#1897709 - 02/24/08 11:31 PM
Re: "warbble" at 1K
[Re: ricotrex]
|
ricotrex
Senior Member
Registered: 09/26/06
Posts: 32
Loc: Santa Clarita, California
|
|
Offline
|
|
NIce BM5A's, by the way! I have the same speakers!
|
|
Top
|
|
|
|
|
#1897728 - 02/25/08 02:48 AM
Re: "warbble" at 1K
[Re: ricotrex]
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
|
Offline
|
|
thanks for the reply (and I love the BM5a's too!), however I already have the panels mounted equal distance from the wall (as their thickness), so all the 4" panels are 4 inches away from the wall.
that is what has me baffled, could it be that the auralex mineral fiber is not absorbing 1K???
I simply could not find ridgid fiberglass in Trinidad and Tobago, I suspect it exists somewhere on this island, but I could not locate it. So i ordered auralex mineral fiber from the states, it is really made as an insulator, to place in walls in order to stop sound from passing thru.
Does anyone have any info on this? And if it IS that these panels (which seem to be absobing bass really well) dont work in the upper ranges, could I simply place acoustic foam on the already existing panels?
Also how can I tell what these panels are doing at 1K?
thanks!
|
|
Top
|
|
|
|
|
#1897921 - 02/25/08 09:28 AM
Re: "warbble" at 1K
[Re: hey_mavis]
|
Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5300
Loc: New Milford, CT, USA
|
|
Offline
|
|
Auralex mineral wool works fine and I'm sure it absorbs well at 1 KHz. Without being there to hear for myself I can only guess. Have you tried measuring your response? What happens if you play only one speaker at a time?
|
|
Top
|
|
|
|
|
#1898007 - 02/25/08 10:48 AM
Re: "warbble" at 1K
[Re: Ethan Winer]
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
|
Offline
|
|
when I play a tone on one speaker at a time it is a little better, but it still depends on how I move my head in the room, if I move it to the left or right the sound changes and I can hear harmonics in one ear more than another (all of a sudden I hear higher harmonics in one ear). If I stand up the problem seems to be less.
It seems to me that there is a null at 1K - 1.5K where I am sitting, but I can't move too much, I moved forward by 6 inches and it helped slightly.
I find the mixes sound good and mixing as improved incredibly, the only issue really is that because everything (from instruments to voice) have 1K components, the room just sounds funny, even talking or hearing the phone ring sounds funny, and it makes working in the studio a lil odd.
Is there a solution beyond removing my back wall and moving it backward?
Perhaps more absorption above my head?
http://i272.photobucket.com/albums/jj174/hey_mavis/GEDC0225.jpg
(above) shot of auralex 1" foam absorption above my head in a 2' by 8 rectangle, this pic also shows the tops of the red 4" panels on the front wall.
Also that ceiling is 8'9" above my head, but it's a thin false wood ceiling and about 2 feet above it is a solid concrete ceiling parallel to the floor (which serves as the floor for the next story of the house).
thanks!
link to all my studio photos:
http://s272.photobucket.com/albums/jj174/hey_mavis/
PS. are my panels too high on the walls? my corner panels are floor to ceiling, the side ones start at 3 feet off the floor which is the hight of my desk, should they be lower?
Edited by hey_mavis (02/25/08 01:27 PM)
|
|
Top
|
|
|
|
|
#1898720 - 02/26/08 07:46 AM
Re: "warbble" at 1K
[Re: hey_mavis]
|
Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5300
Loc: New Milford, CT, USA
|
|
Offline
|
|
It all looks fine. Maybe one of your speakers is miswired out of phase? What happens if you physically swap the speakers?
|
|
Top
|
|
|
|
|
#1898748 - 02/26/08 08:11 AM
Re: "warbble" at 1K
[Re: Ethan Winer]
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
|
Offline
|
|
I will try that, swapping the speakers, but how can I test if the tweeters or the woofers are wired out of phase? is there a way to test that?
I tried sending a test tone of 1K to each speaker at the same volume panned hard right and hard left, and I flipped the phase of on speaker at a time, when they were out of phase the tone disappeared from my right ear, I only heard it on my left side. this occured no whether it was the left or right channel I flipped the phase on.
I changed the speakers around it does not seem to make a huge difference to the peak/null effect when I move my head around and have a 1K tone playing, when i walk around the room I can hear the tone going up and down in volume and I can move my head side to side or forward in and out of nulls, there is a point where the 1K tone almost disappears!
Is this normal?
Edited by hey_mavis (02/26/08 04:38 PM)
|
|
Top
|
|
|
|
|
#1899144 - 02/26/08 04:43 PM
Re: "warbble" at 1K
[Re: hey_mavis]
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
|
Offline
|
|
also I played tones and flipped phase on one channel in and out and above 2K I can't hear a different, except that at times the tone seems louder when it is out of phase.
my monitors (Dynaudio BM5A's) cross over at 1.5K so I suppose the tweeters could be wired out of phase, but then when I flip the phase I should hear it no?
I tried setting up a mix and rolling off everything below 1700Hz and flipping each channel, and then rolling off everything above 1700Hz, even on a full song I could hear the difference with the lower frequencies but not the higher ones.
Anyone have any ideas as to what is going one here?
|
|
Top
|
|
|
|
|
#1899680 - 02/27/08 10:29 AM
Re: "warbble" at 1K
[Re: hey_mavis]
|
Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5300
Loc: New Milford, CT, USA
|
|
Offline
|
|
First, I really doubt there's anything wrong with your speakers. And if there is, hopefully it's only one and not both. So physically exchanging them might will tell you if one is possibly wired wrong.
--Ethan
|
|
Top
|
|
|
|
|
#1899905 - 02/27/08 03:19 PM
Re: "warbble" at 1K
[Re: Ethan Winer]
|
hey_mavis
Member
Registered: 12/16/07
Posts: 29
Loc: Trinidad and Tobago
|
|
Offline
|
|
so I've noticed that it (peaks and nulls) occur at 250 500 1K 2K 4K etc etc
so it must be the room.
I don't suppose there is anything I can do about it?
|
|
Top
|
|
|
|
Moderator: Ethan Winer
|
|
|
