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Floor reflections - hide or not?

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AndreasN:
Is it benefital to hide the first reflections from the floor?


Recently built a tiny little desk/console for my wee mastering room. It holds the bare minumum of stuff needed to do most of the work in the sweet spot. The goal was to get rid of the annoying first reflections from the desk itself. It sounds nearly as nice as not having anything at all between listening spot and speakers. So far, so good! To the point:

Was playing around with a mirror on the floor to find the first reflection points there, when the idea came that the reflections from the floor itself could be hidden too. (me thinks, hope this train of thought is not totally erroneous!) If the desk where to be extended with some wood pieces (or acoustic foam?) on the sides, they could be made to block the direct path from the floor to the ears. Something like the pic below shows. It's a mock up done in an hour and not a final desk design. Picture is not to scale or geometrically correct, but it hopefully gives the right impression of the idea:




It's like moving stand mounted speakers further and further rearwards from a desk until the mirror reflections disappear behind the desk. Except that I now have the choice to block or not block these first reflections from the floor. Is blocking these reflections a typically good thing to do? Would two small rugs in the reflection spots on the floor serve the purpose better? Would acoustic foam be better than a rug? Or leave the reflections alone..?

My ears doesn't tell me that much as I can't A/B these designs with a switch and my audio memory only lasts milliseconds. Good test equipment is unfortunately unavailable. Haven't seen any mention of this subject as I've searched the net. Hope someone may shed some light on it!


Cheers,

Andreas Nordenstam

PS: the floor is cheap wood panel look alike vinyl covering on concrete.

franman:
Yes floor reflections count!! I would suggest some 4" acoustic foam at the reflection spots.. We can hear it in our office very easily!!

L_Tofastrud:
You could "hide it" like you're talking about.  One thing to think about is the wavelenght of the frequencies you're trying to stop.  If the table top is small in comparison to the wavelenght it's no use.

If the drawing is representative of your situation I would try with some 4" or more damping material (foam) on the floor where you had the mirror.

Regards
Lars Tofastrud

AndreasN:
L_Tofastrud wrote on Wed, 23 August 2006 22:04
One thing to think about is the wavelenght of the frequencies you're trying to stop.  If the table top is small in comparison to the wavelenght it's no use.


Ahh.. Diffraction! Didn't think about that.

With the intended size, it would probably only be good for about a kiloHertz or two and upwards.

Will try some 4" mineral wool or foam on the floor instead. Thanks for the help!


Cheers,

Andreas N

franman:
Thanks Lars!! As always.. he's right on top of it!! (my Man!!)

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