Hi Steve,
Bass tilt :off
Bass rolloff: off.
Pictures below L-corner R-corner 40-305hz
Thank you
Wall/slot
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knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
Yiannis, sorry for the delay (I only need 36 more hours a day and I might be able to keep up :=)
I'm thinking from your pix, etc, that the mic was sitting too close to all that absorption and not at the very peak of the room corner - that could place the mic in an anti-node, as well as cause more absorption of the highs, which would cause your graph to look like it does - the positioning I mentioned is normally used BEFORE any treatment, so you can get an idea of what the room needs; where you were forced to put mic and speaker is quite a ways away from the boundaries of the room so results won't be the same.
On the slat question - down around 150 hZ, a 1 meter wide helmholtz presents its ENTIRE FACE to about a HALF wave length; so nearly anything you do from one side of the slat to the other, will likely be AVERAGED as far as response goes. For higher frequencies, this tends to be LESS true but still enters into the results.
About the only way I know of to get much "averaging" out of varied slot width and depth, is to build "separators" into the device while assembling so that each slat (or pair of slats maybe) has its OWN SEPARATE cavity to work against - this makes the unit into several separate resonators each with its own characteristic frequency.
For your room, maybe try LOTS of measurements while moving the speaker away from the wall(s) about 2" at a time (50mm) - make note of where it is the most even, then place it there and start moving the mic around your potential recording position until the curve smooths out some more; this includes HEIGHT changes for each, as well.
It's very time consuming, but hard to do any other way with a room like yours because there are too many things getting in the way of calculations (plus, calculations are only a starting point anyway :=)
This type of measurement is where ETF software really helps; you can set it to "machine gun" mode, so it "fires" about once a second - then you just watch the screen and move things slowly til it gets better or worse... Steve
I'm thinking from your pix, etc, that the mic was sitting too close to all that absorption and not at the very peak of the room corner - that could place the mic in an anti-node, as well as cause more absorption of the highs, which would cause your graph to look like it does - the positioning I mentioned is normally used BEFORE any treatment, so you can get an idea of what the room needs; where you were forced to put mic and speaker is quite a ways away from the boundaries of the room so results won't be the same.
On the slat question - down around 150 hZ, a 1 meter wide helmholtz presents its ENTIRE FACE to about a HALF wave length; so nearly anything you do from one side of the slat to the other, will likely be AVERAGED as far as response goes. For higher frequencies, this tends to be LESS true but still enters into the results.
About the only way I know of to get much "averaging" out of varied slot width and depth, is to build "separators" into the device while assembling so that each slat (or pair of slats maybe) has its OWN SEPARATE cavity to work against - this makes the unit into several separate resonators each with its own characteristic frequency.
For your room, maybe try LOTS of measurements while moving the speaker away from the wall(s) about 2" at a time (50mm) - make note of where it is the most even, then place it there and start moving the mic around your potential recording position until the curve smooths out some more; this includes HEIGHT changes for each, as well.
It's very time consuming, but hard to do any other way with a room like yours because there are too many things getting in the way of calculations (plus, calculations are only a starting point anyway :=)
This type of measurement is where ETF software really helps; you can set it to "machine gun" mode, so it "fires" about once a second - then you just watch the screen and move things slowly til it gets better or worse... Steve
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...