# beginner - how to identifíy a specific 'dip'



## Balazs Rozgonyi (Jun 3, 2017)

Hi

We are constructing an editing room that may need to do some audio premixing etc. Its not a very high end audio setup - that may come later - but its fairly good electronically. However I'm pretty beginner when it comes to acoustics, even though I learned a bit in my University.

Room is about 6x3 meters (little less because of the insulation, 2,4m high. Installed are 5x Tannoy System 600 studio speakers and a 5-channel power amp. This mainly a video editing room, there is a 55" OLED on the wall, and currently a desk and a sofa. There will be 3 more 25" screens, two for the computer, one a broadacast SDI screen.

For sound insulation, we built a metal frame inside the room, with a 30cm air gap, covered it with OSB panels, and that was covered with absorbing materials and fabrics on 3 sides. Carpet on the floor. On the ceiling originally it was the basic 600x600mm drop in ceiling, but some we replaced with foam and absorbers. Behind the main speakers and screens is a similar material you use on drop-in ceiling, painted 18% gray. On every second absorber, we attached a wodden design of triangular shapes as reflectors. I added two photos of the room.

For REW, I bought a DBX RTA-M measurement mic, and connected it to a Focusrite Scarlet 2i2. REW runs on my macbook.

By listening I'd say the room is faily silent, sounds ok, but there is a metallic like quick reflection which I wanted to hunt down with REW. But I wasnt expecting opening a can of worms.

I attached a pic of the FR, which is not terrible, but there is a HUGE dip at 100Hz, another at 138 and 246. And the high end has serious comb filtering. I have spent the day moving absorbers around, covering the diffusers, the TV, behind the monitors, etc, and almost none of them made any change to the low end dips. I also attached filtered IR and waterfall, which looks OK to me, but I'm a beginner.

What do you think? what can cause those dips and combing? Do I need more treatment? or is it something I cannot really correct?

Thanks in advance
Balazs


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## fschris (Oct 31, 2009)

what size is your room?

also a micro fiber and cloth couch is a better option. leather causes reflections


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## Balazs Rozgonyi (Jun 3, 2017)

4,28 x 2,8 x 2,23 meters. 26,7 m3 
about 14 x 9 x 7 in feet. 944 ft3

We had a very similar pattern measured before the couch was brought in..so I suspect thats not the problem, but thanks, maybe we cover it with something.


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