Some guides to REW and acoustic measurement

DxTrEm3Fx

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Jun 23, 2019
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My AV System  
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Yamaha Aventage RX-A3070BL
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Emotiva XPA-9
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Klipsch RP-280FA
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thalro

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Jan 7, 2020
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Hello,

I am new to REW and would like some advice about measuring a recording room. I have searched extensively but all the information seems to be about listening and mixing rooms. My understanding is that the same analyses should also make sense for recording rooms, but how would I set up the speaker and mic? If I for example want to find a good spot in the room for recording guitar, would I place my monitor-speaker at the spot where the guitar would be and the mic in front of it? does that make sense? Or does the position of the speaker not matter so much for this kind of measurement?

thanks in advance!

thomas
 

DanDan

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Mar 10, 2018
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Different purposes, goals. In a listening room we hope to achieve an optimum response in a small area. At ultimate pro level, a bigger area, but practically speaking, even in such expensive surroundings, only a small sweet spot lies within the field of the monitor speakers. On the other hand, a recording room will typically be optimised for enhancing particular sounds. Ideally one might have a large room capable of being divided by giant gobos to accommodate full band or orchestra. Abbey Road. More practically and commonly, drums will have a room, piano, vocalist, all separate rooms. A drum room or indeed zone within a larger room, will have a different, opposite requirement, to a vocal spot or booth. Drums need reflections, vocal recordings are clearer with none. So by all means use a speaker and mic throughout the room to test responses. I would also encourage playing isolated multitrack sounds on the speaker and recording. Note though that resonant sources will react to room feedback but of course playback cannot. Also do a full modal map of the room by placing speaker in a tri corner, and mic in the opposing tricorner. It is extremely useful to know where the strongest peaks and dips and ringing are.
 
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thalro

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Jan 7, 2020
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Hey DanDan,

thanks for the quick reply. I'm talking strictly abourt home recording. I mainly record vocals and guitar and find it difficult to tell the difference between locations and various absorber-placements etc. But the speaker-and-mic-moving method makes sense? I will also try to do a modal map. Do you happen to have any hints where I can read up on this?

Thanks,

T.
 

DanDan

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You are welcome. The speaker and mic thing is absolutely fine. It should show up trouble. But a knowledge of the likely and actually present modes and their strength will deliver certain no fly zones with minimal effort. e.g. Let's say we have an 8' ceiling, minimal or no treatment.
At 4' there will be a massive null around 73Hz, and a strong peak around 150Hz. A seated male vocalist will have his manhood removed and be turned into a Honky. Simply standing will radically improve his chances of finding a mate......
Eigenmodes, room modes can be nicely graphically predicted here https://www.hunecke.de/en/calculators/room-eigenmodes.html
But I would encourage an actual modal map. Place your speaker in a corner on the floor, mic opposite, ideally at the ceiling tricorner. REW sweeps, maybe try another corner while you are at it. Restrict the Waterfall plot to say 500Hz or whatever to highlight the long ridges ringing modes. Use the Signal Generator, Sine, Frequency follows cursor. Slide the cursor over the lowest, then walk the room. You will be stunned by the absolute null mid room and the chest massaging levels at the two walls supporting this mode. etc. Masking tape on the floor, or a full map. You will now know where the booms and dry spots are. Don't forget height.
 

thalro

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Jan 7, 2020
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Wow, thanks for the detailed explanation. This is really helpful, DanDan!
 
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