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Make sense to start from REW room simulations ?

jmf11

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Hello,

I'm starting to setup a 2.1 KH80+SVS SB-1000 system in my room. Unfortunatly, it's not a dedicated room, and so there are a lot of positionning constraints: MLP fixed by couch location, Subwoofer location fixed by WAF. But for more serious listening sessions, I can move the speakers (small and light) inside the room. I can EQ the speakers and the subwoofer, I have an UMIK microphone. So the idea is to find acceptable best (in contraint space) speakers location to reduce issues and then DSP.

I have read the Genelec and Neumann instructions for installation. Basically they say that in case of usage of a subwoofer, the main speakers should be away from the back wall of more than 1/4 the crossover frequency corresponding wavelength.

Today I played with REW room simulator, and discovered that in my room, the 100-300Hz range is quite sensitive to the position of the speakers. Very small changes in location create big dips. The left sepaker position also seem to be very sensitive.

Does it makes sense to work-out best/worse theoritical positions of the speakers based on REW room simulator? Other tools to identify good candidate positions or positions to really avoid ? Or are those simulators not accurate enough to process like that?

Advices welcomed to reduce trials and errors ;-)

Attached a screen shot. in red a crude representation of the ceiling slope (not possible to simulate in REW).

JMF
 

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NTK

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Those densely packed dips and peaks that are very sensitive to small shifts in listening or speaker positions are usually not be a problem. As explained by Dr Toole, our two ears and a brain tend to ignore/adapt to them as the "room sound".

Taking the non-minimum phase story to the next level, the underlying issue is that the mic and analyzer are showing what looks like a problem - the acoustical interference of the direct sound and a reflection. However, because the direct and reflected sounds arrive from different directions, which the mic cannot recognize, it is ignoring the reality that two ears and a brain can recognize the difference. What looks like possible audible coloration is interpreted by humans as simple, innocuous spaciousness - a.k.a. a room. Humans have considerable abilities to separate the timbral identities of a sound source from those added by a room. It happens in all live, unamplified, music performances and all conversations.

We have no measurement apparatus that performs as a living binaural hearing system,
 
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jmf11

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Those densely packed dips and peaks that are very sensitive to small shifts in listening or speaker positions are usually not be a problem. As explained by Dr Toole, our two ears and a brain tend to ignore/adapt to them as the "room sound".
Thanks for sharing. Looks like no need to overdo it with simulation => place the speakers, measure, smooth a bit and look if there remain some big dips.
 

ozzy9832001

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Feb 19, 2023
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Hello,

I'm starting to setup a 2.1 KH80+SVS SB-1000 system in my room. Unfortunatly, it's not a dedicated room, and so there are a lot of positionning constraints: MLP fixed by couch location, Subwoofer location fixed by WAF. But for more serious listening sessions, I can move the speakers (small and light) inside the room. I can EQ the speakers and the subwoofer, I have an UMIK microphone. So the idea is to find acceptable best (in contraint space) speakers location to reduce issues and then DSP.

I have read the Genelec and Neumann instructions for installation. Basically they say that in case of usage of a subwoofer, the main speakers should be away from the back wall of more than 1/4 the crossover frequency corresponding wavelength.

Today I played with REW room simulator, and discovered that in my room, the 100-300Hz range is quite sensitive to the position of the speakers. Very small changes in location create big dips. The left sepaker position also seem to be very sensitive.

Does it makes sense to work-out best/worse theoritical positions of the speakers based on REW room simulator? Other tools to identify good candidate positions or positions to really avoid ? Or are those simulators not accurate enough to process like that?

Advices welcomed to reduce trials and errors ;-)

Attached a screen shot. in red a crude representation of the ceiling slope (not possible to simulate in REW).

JMF
Almost all rooms unless they are gigantic start to have tangential and oblique modes stack up in the upper bass. It's normal and not much you can do about it. Treatment would certainly help, but those modes are created by 4 and 6 boundaries so they can get tricky. Their impact is typical fairly minimal.

Keep in mind that the room simulator is just designed for ideal scenarios and doesn't take into consideration building materials, windows, doors, closets, carpet, etc.

Typically, we want to avoid the corners of rooms, though smaller speakers can benefit from the bass increases by placing them there. Half way into the room is another bad place either for your listening position or the speakers.

However, as with all things, experimentation is the key. I'd honestly recommend a calibrated microphone and use REQ to measure the rooms response. This will give you a better indication with how it actually handles the sound.
 

abdo123

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You should use the simulations only if it’s too much of a hastle to move things.

Because actual measurements will always be more accurate.
 

Andysu

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REW sim just a rough guide - line which is close but can't draw the actual shape of the room into the simulator
 
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