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What are the acoustic consequences of having a tall rack of equipment between two speakers?

krabapple

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As in, occupying the 'space' where the phantom center manifests itself.

One sees a lot of setups like this in photos of rooms: racks of gear that come up at least to the level of the woofers, if not the tweeters. Stuck smack in the middle of front left and right. The rack might be front-aligned with the speakers, or set back from their baffle plane. There might be vertical space between the components in the rack, or they could form a nearly solid tower.

Surely all this has some effect on the propagation of sound in the room to the MLP? Or is any effect mostly psychological?

Thoughts, best/worst practices?
 
As in, occupying the 'space' where the phantom center manifests itself.

One sees a lot of setups like this in photos of rooms: racks of gear that come up at least to the level of the woofers, if not the tweeters. Stuck smack in the middle of front left and right. The rack might be front-aligned with the speakers, or set back from their baffle plane. There might be vertical space between the components in the rack, or they could form a nearly solid tower.

Surely all this has some effect on the propagation of sound in the room to the MLP? Or is any effect mostly psychological?

Thoughts, best/worst practices?
I think there would be some impact on the sound, whether it is easy to hear, harder to say.

I think best case, the gear acts something like a diffuser and effectively scatters sound that would have otherwise reflected off the front wall.

Another possibly good outcome is the gear acts like a solid wall and effectively extends the baffle, so you get some bass reinforcement... not a great outcome because tower / bookshelf speakers are not voiced for that, so you'd need to EQ it back down.

Worst outcome is the gear diffracts a bunch of mids and highs and you end up with a messy / diffuse stereo image.

I am not sure to what extent the various effects would pertain.
 
My first thought is to wonder about the effect on phantom center.

Personally I employ magical thinking to conclude that it's better to have the gear low to the ground, if it must be in between the speakers.
 
My first thought is to wonder about the effect on phantom center.

Personally I employ magical thinking to conclude that it's better to have the gear low to the ground, if it must be in between the speakers.
I don't know if that's magical thinking or just conservative decoration.

Physical objects reflect sound, we don't need measurements to tell us that. So to that extent it makes sense to avoid extraneous objects near the speakers in the plane of tweeter / ear.

How much sound they reflect, at what frequencies, at what directions, what the cumulative effect of all the reflections is, and how audible that is are separate questions that might demand very complex measurements.
 
My first thought is to wonder about the effect on phantom center.
I have a 3rd full-size center speaker in between the L/R speakers and, when I play stereo, the phantom center is excellent. In fact, it seems even better than without the silent center because of its visual effect. :)
 
An increase in midrange glare? :D

This is a good question and I’ve thought about it myself. I started thinking about it once I started using a curved diffuser behind in between my loudspeakers, which seems to clearly affect the sound: they seem to be more density to the imaging especially the centre image. As well as some slight tonal changes. I like the effect.

And when I would go over to some of my friends house and they’ve got their big racks in between behind the speakers, roughly where my curved diffuser ends up, it’s made me wonder what effects their rack is having the sound. I’m sure it must have some effect.
And I wondered whether this is anything like the curved diffuser, altering the tone somewhat, and possibly adding some sense of density for centre images with the sound reflecting off those points between the speakers? Why would the entirely different geometry of equipment on a stand is going to be different or less predictable.

I’m happy to have virtually nothing between my loudspeakers (except a centre channel low to the ground), so that I can have some control over what I introduce into that space or not.
 
I have a 3rd full-size center speaker in between the L/R speakers and, when I play stereo, the phantom center is excellent. In fact, it seems even better than without the silent center because of its visual effect. :)
I love it! That would seem to be the ideal psych fake-out. :)

(FWIW, when I use a center channel, which I am not doing currently because I like my TV to be eye-level, my upmixer uses the center)
 
Surely all this has some effect on the propagation of sound in the room to the MLP? Or is any effect mostly psychological?
Yes, there is. But it depends on the directivity vs. frequency of your front stereo loudspeakers and their placement relative to the front and side walls. For instance: Corner Horn Imaging FAQ. For loudspeakers having full range directivity (like corner horns and polar dipoles) the effect of anything between the loudspeakers can affect the soundstage/imaging greatly.

What kind of loudspeakers do you have?

Chris
 
Behringer 2030P monitors, directivity reported by Amir as: Directivity control in the horizontal axis is very good, providing near constant response for much of audible spectrum.

I toe them in ,as well. (And the two surrounds are the same. )
 
Personally, I don't believe that I'd call those "controlled directivity" unless talking above 1 kHz. Most of the midrange is below that frequency.

Behringer_B2030p_Speaker_Pro_Monitor_Beam_Width_measurements[1].png


Vertical is typical for this sort of loudspeaker (no directivity plot but a polar sonogram instead):

Behringer_20B2030p_20Speaker_20Pro_20Monitor_20Vertical_20directivity_20measurements.png


Could you describe the placement of them with respect to the front and side walls, the distances? And the width, length, height of your room? How far away are the loudspeakers from your center rack?

Chris
 
As in, occupying the 'space' where the phantom center manifests itself.

One sees a lot of setups like this in photos of rooms: racks of gear that come up at least to the level of the woofers, if not the tweeters. Stuck smack in the middle of front left and right. The rack might be front-aligned with the speakers, or set back from their baffle plane. There might be vertical space between the components in the rack, or they could form a nearly solid tower.

Surely all this has some effect on the propagation of sound in the room to the MLP? Or is any effect mostly psychological?

Thoughts, best/worst practices?

I don't think it's an issue, but you can make sure by doing measurement sweeps with REW and comparing the ETC plots with the rack and with it moved out of the way.

 
Just what an audiophile needs: something else to be paranoid about…:)
 
As in, occupying the 'space' where the phantom center manifests itself.

One sees a lot of setups like this in photos of rooms: racks of gear that come up at least to the level of the woofers, if not the tweeters. Stuck smack in the middle of front left and right. The rack might be front-aligned with the speakers, or set back from their baffle plane. There might be vertical space between the components in the rack, or they could form a nearly solid tower.

Surely all this has some effect on the propagation of sound in the room to the MLP? Or is any effect mostly psychological?

Thoughts, best/worst practices?
It's about the speaker positioning. And it can be measured and compensated for. Surely there's no universal rule anyone will answer with. But at least position the speakers so that their front is aligned with the front of the equipment tower, I haven't had an equipment tower in many years.
 
Personally, I don't believe that I'd call those "controlled directivity" unless talking above 1 kHz. Most of the midrange is below that frequency.

View attachment 409808

Vertical is typical for this sort of loudspeaker (no directivity plot but a polar sonogram instead):

View attachment 409809

Could you describe the placement of them with respect to the front and side walls, the distances? And the width, length, height of your room? How far away are the loudspeakers from your center rack?

Chris
I didnt start this thread for advice on my own setup ( where there is no rack nor need for one) . I think you've misunderstood.
 
It's about the speaker positioning. And it can be measured and compensated for. Surely there's no universal rule anyone will answer with. But at least position the speakers so that their front is aligned with the front of the equipment tower, I haven't had an equipment tower in many years.
No rule but surely general principles that can enlighten the readership ?

Why is alignment important, for example?
 
I don't think it's an issue, but you can make sure by doing measurement sweeps with REW and comparing the ETC plots with the rack and with it moved out of the way.

Im wondering if anyone has investigated this already.
 
No rule but surely general principles that can enlighten the readership ?

Why is alignment important, for example?

I'd say that most speakers perform closer to their intended spec in environments where acoustic waves/signals encounter the least rebound opportunities to muddle up things. Why add something close to their front?

Even when I had a rack at speaker height between them (Mid 90s, never since), I'd position the speakers' front several inches in front of the rack tower. Simply makes sense intuitively (to me).
 
I'd say that most speakers perform closer to their intended spec in environments where acoustic waves/signals encounter the least rebound opportunities to muddle up things. Why add something close to their front?

Even when I had a rack at speaker height between them (Mid 90s, never since), I'd position the speakers' front several inches in front of the rack tower. Simply makes sense intuitively (to me).
The speakers themselves as far as these encounters or what about the rooms ?
 
I didnt start this thread for advice on my own setup ( where there is no rack nor need for one) . I think you've misunderstood.
There is no "generic" advice on this particular subject, only specific instances that need to be considered.

What I was going to show is that you can estimate whether or not you're going to have issues based on loudspeaker directivity (yours), and placement relative to the walls. All of these distances can be used to estimate the 1/4 and 1/2 wavelength distances vs. frequency reflections as a function of the distance to center racks and room walls.

The distance to your listening position can also affect whether or not you're at the so-called critical distance from your loudspeakers. If you're outside that listening distance, the direct/reflected energy level will be less than 0.5, and you will likely not hear any effects of a center rack, but only if the loudspeakers are outside 1/2 to 1 wavelength reflectors, but above the so-called Schroeder frequency of your room and are still controlling their polars. (In your case, they're not controlling their polars in that band--so you probably will not hear the center rack reflection issues.

But I guess you didn't really want a real answer.

BTW: these sort of soundstage effects are difficult to see on a filtered IR plot, because the human hearing system is quite sensitive to nearfield reflections, but only if the direct/reflected ratio is still pretty high. If you're using Bose 901s in-room boundary effect, basically all you're hearing is reflected energy, so they're equally bad--wherever you put them in room (except bass response in boundary effect).

Chris
 
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