Reverse subwoofer measurement

[Digital_Thor]

Hi all happy hifi people

I've been fiddling with an idea.
Is acoustic measurements reversible?
Meaning, could you place a small linear subwoofer in your listening position and measure around the room and hereby better reveal where optimal positions might be?

 

[mags65]

My guess would be «no», as boundary distances, reflections etc. would differ radically between the MLP and potential SW positions.

 

[Holmz]

Hi all happy hifi people

I've been fiddling with an idea.
Is acoustic measurements reversible?
Meaning, could you place a small linear subwoofer in your listening position and measure around the room and hereby better reveal where optimal positions might be?

Yeah - it’s called reciprosity.

 

[TimVG]

Aka the sub crawl.

 

[Digital_Thor]

Aka the sub crawl.

Yep, I know that one.
But would it give meaningful data to measure it, maybe even show wether a given placement is in no way good.
Earl Geddes have some rule of thumb, which roughly say, one in a corner, one in the back and one somewhere in the middle. The rest should be up to simple gain, phase and EQ.

 

[TimVG]

Yep, I know that one.
But would it give meaningful data to measure it, maybe even show wether a given placement is in no way good.
Earl Geddes have some rule of thumb, which roughly say, one in a corner, one in the back and one somewhere in the middle. The rest should be up to simple gain, phase and EQ.

You'd need to get your sub at the MLP at head height, but sure - it would work.

 

[No. 5]

Hi all happy hifi people

I've been fiddling with an idea.
Is acoustic measurements reversible?
Meaning, could you place a small linear subwoofer in your listening position and measure around the room and hereby better reveal where optimal positions might be?

Yes, I've done that. Play pink noise and move an RTA's microphone around the room to potential subwoofer locations. It works very good, in my opinion it's a better method than crawling for bass provided that you have the microphone and whatnot.

Added technical note: I recommend using a signal like REW's Pink PN since it'll make the RTA readout will be a lot more readable.

 

[Holmz]

I find it easier to move a microphone around the room, than to move a big speaker.
Ideally one might also try microphone locations above the floor, but that assumes that the sub could sit somewhere elevated, and doesn’t attract WAF-ire.

 

[Digital_Thor]

I'm merely brainstorming here, and by that, it sometimes help to throw out ideas that then get tumbled around until the original approach get solidified more.
Thanks guys
I pretty much use the Geddes approach and then add a few compromises to make it work with my system, and I'm very happy with the result, even without FIR or any automated system like Dirac and the like.