Dr. Floyd Toole' system - with pictures

[speedy]

Regarding near wall, pointed out many times:

http://arqen.com/acoustics-101/speaker-placement-boundary-interference/
https://www.genelec.com/sites/default/files/media/Studio monitors/Catalogues/monitor_setup_guide_2017.pdf
https://www.genelec.com/documents/publications/PlacementandRoomAcousticsInteraction.pdf
#38

etc

I read those articles just now and the math makes sense about putting the speakers as flush as possible against the front wall, but why do so many speaker manufacturers and internet "experts" state that speakers should have sufficient "breathing room" from the front wall (specifically with regard to imaging).

For example, the manual for my speakers states:

The speakers should be approximately 0.5m away from the back wall

 

[DonH56]

Are your speakers rear-ported?

Near-boundary placement also provides a bass boost and some manufacturers specify some distance to provide flatter bass response.

And some probably just get it wrong, e.g. manual written by marketing or some person who decided how he likes them when he heard them...

SBIR messes up imaging through comb filtering etc. and, since you cannot flush mount stand-alone speakers, they probably try to get them far enough away that the first null is low enough in frequency to not be obvious.

 

[Sal1950]

Does anyone have any ideas what the reasoning is for this configuration? (maybe it's just purely aesthetic and Dr. Toole lives in a real home like the rest of us)

As I remember Dr Toole has posted they are that way simply to put the tweeters at ear level, they would be way too high and off axis if mounted conventionaly on that cabinet.

 

[speedy]

Are your speakers rear-ported?

Near-boundary placement also provides a bass boost and some manufacturers specify some distance to provide flatter bass response.

And some probably just get it wrong, e.g. manual written by marketing or some person who decided how he likes them when he heard them...

SBIR messes up imaging through comb filtering etc. and, since you cannot flush mount stand-alone speakers, they probably try to get them far enough away that the first null is low enough in frequency to not be obvious.

They're front ported speakers. I wonder if the manufacturer assumes customers won't place the speakers directly up against the wall for aesthetic reasons so they instead recommend pulling them out far enough to move the SBIR below typical home theater crossover frequencies.

With my current placement, it seems like my SBIR null is at ~94Hz (~36" from front wall) so I crossover my mains at 100Hz to avoid the SBIR. If I push my speakers closer to the wall then the SBIR moves up above a reasonable crossover for my main speakers (I don't want a 120Hz or 150Hz crossover).

If I understand correctly, I'd need to pull the speakers even further out into the room for the SBIR null to go lower, correct?

The thing I don't understand is... the Salon2 is a big speaker... 23" deep... shouldn't that cause it to have 147Hz SBIR null when wall mounted (SBIR = (1125 * 12) / (4 * 23))? If so, then isn't 147Hz a bad frequency to have the SBIR null at if your subs are crossed over at 80Hz?

I'm probably missing something about the way SBIR nulls work once the frequency is as high as 147Hz or my math/understanding is wrong.

 

[DonH56]

Speakers aren't my day job; ask Dr. Toole. But, boundary effects get a little squirrely in the very near-field region, the speakers become more directive, and the woofers are up high in his installation leading to greater path length to the listener, so there may not be much of a null at the MLP. But again this is outside my field so I'll defer to the experts.

 

[Thomas_A]

I read those articles just now and the math makes sense about putting the speakers as flush as possible against the front wall, but why do so many speaker manufacturers and internet "experts" state that speakers should have sufficient "breathing room" from the front wall (specifically with regard to imaging).

For example, the manual for my speakers states:

I don’t know what the typical wording ”breathing” means in terms of speakers other that you should not block any ports etc. Another reason could be to allow reflection outside the 2ms window not get problems with the summing location and diffuse imaging. But if you have eg a waveguide tweeter you have the omnidirectional pattern increasing with the baffle step function below 1000 Hz or so. Below this region you will have boundary effects and comb filtering. IMO the direct sound will be affected by this filtering since both sounds come from the same direction. Damping panels behind the speakers will improve details significantly. Lateral reflections are much less destructive as long as they are sufficiently delayed and/or damped in level since they arise from another angle compared to the direct sound. We are used to have those images/reflections.

I don’t know if Floyd Toole ever have commented on the front wall effects in his setup with respect to SIBR.

 

[Beershaun]

Posting the blog post with pictures since the OP linked pictures seem to be gone.

https://www.thescreeningroomav.com/...te-real-world-home-theater-and-listening-room