Why should I remove furniture before taking room correction measurements?

[jcarys]

NBA players?

PS: I measure my room as it is.

It's not just depth distance, it's also height. Sitting upright on my couch, my ears are 10" away from the nearest rear cushion. If you have a more modern style (low back), it could definitely be a full foot. It's Dirac's instructions, not mine!

 

[tvrgeek]

The entire point of room correction is to equalize the room as it will be used. Otherwise we would build flat speakers and not need any eq.

I do slow sweeps to look for resonances. I once found a window balance spring would buzz, and the back of a cabinet worked as a resonator. Both fixed, better sound. Take care of resonances like that before you do eq.

I suppose some big stuffed furniture could act like a bass trap if positioned in just the wrong ( or right) place so it could effect LF, but I doubt it would be significant.

 

[Hipper]

We're not really equalising the room though are we but the effect of the room on the sounds coming from the speaker as it's heard at the listening position. It doesn't matter what the sound is like at other places in the room - indeed it can be very different.

 

[andreasmaaan]

How much impact does typical furniture - sofas, hi-fi gear, shelving, books etc. - have on frequencies below the Schroeder frequency?

Sofas can have effects as absorbers/reflectors. Shelves, too, if they are full of solid objects like books, are effective reflectors (they are unlikely to be diffusers at sub-Schroeder frequencies).

Basically, the more massive the piece of furniture, the more likely it is to have some effect on sub-Schroeder response.

However, I don't think anyone is suggesting completely emptying the room of furniture before measuring, but rather just moving anything that's within a couple of feet of the microphone out of its way, because reflections from very near objects will have a serious impact on what the mic measures, while being unlikely to have as great a subjective impact on what a listener perceives (for example, because they are used to sitting on a couch and the reflections off the cushion behind them form a normal part of the soundfield, which should therefore not be compensated for).

 

[detlev24]

Sofas can have effects as absorbers/reflectors. Shelves, too, if they are full of solid objects like books, are effective reflectors (they are unlikely to be diffusers at sub-Schroeder frequencies).

Basically, the more massive the piece of furniture, the more likely it is to have some effect on sub-Schroeder response.

However, I don't think anyone is suggesting completely emptying the room of furniture before measuring, but rather just moving anything that's within a couple of feet of the microphone out of its way, because reflections from very near objects will have a serious impact on what the mic measures, while being unlikely to have as great a subjective impact on what a listener perceives (for example, because they are used to sitting on a couch and the reflections off the cushion behind them form a normal part of the soundfield, which should therefore not be compensated for).

I can only second this explanation.

There's a nice experimentation by Ethan Winer, the part on COUCH AND CHAIR REFLECTIONS, revealing an increase in comb filtering (not good^^).