Shootout between JBL M2 and Revel Salon 2

[DonH56]

The more directive a speaker's driver(s) the less energy is radiated to the sides (and floor/ceiling) to be reflected.

 

[RayDunzl]

what is the mechanism here that is creating more physical, indirect sparse/specular reflections?

Consider a spotlight vs a floodlight.

 

[QMuse]

Consider a spotlight vs a floodlight.

Or consider your MLs vs JBLs.

 

[Bjorn]

It's really more "lower level" of the reflections (lateral in this case) in a certain frequency range rather then avoiding it. Even with a horn that has a 90° horizontal directivity, audible side wall reflections isn't avoided in most small rooms. And at certain point, depending on the dimension of the horn/driver, the directivity is lost and the level of side wall reflections will go up in that frequency area.

 

[localhost127]

The more directive a speaker's driver(s) the less energy is radiated to the sides (and floor/ceiling) to be reflected.

but that still doesn't satisfy the claim that "more reflections" are created. you could state (as my original reply eluded to) that a loudspeaker with wider dispersion would have more mid/HF energy present off-axis which would change the spectral content of the first-order, sidewall reflection (even to the extent it could be perceived) - but a wider dispersion simply modifies the frequency content of that individual reflection. how exactly are "more reflections" created?

 

[localhost127]

It's really more "lower level" of the reflections (lateral in this case) in a certain frequency range rather then avoiding it. Even with a horn that has a 90° horizontal directivity, audible side wall reflections isn't avoided in most small rooms. And at certain point, depending on the dimension of the horn/driver, the directivity is lost and the level of side wall reflections will go up in that frequency area.

sure, but this is simply modifying the spectral content of that reflection, not "creating more reflections". creating more reflections would imply some modification to the bounded acoustical space such as the placement of a phase grating diffuser, or multiple "flat/planar" surfaces at the sidewall angled to introduce numerous, spaced specular reflections to the listening position.

what is the mechanism by which a loudspeaker with wider polar dispersion than another is somehow "creating more physical reflections"?

 

[Bjorn]

That's semantics IMO. The fact is that you have more specular reflections with higher gain in the listening position with speakers with a wide dispersion. In that way, it's "creating" more reflections" compared to a speaker with very narrow directivity.

 

[napilopez]

sure, but this is simply modifying the spectral content of that reflection, not "creating more reflections". creating more reflections would imply some modification to the bounded acoustical space such as the placement of a phase grating diffuser, or multiple "flat/planar" surfaces at the sidewall angled to introduce numerous, spaced specular reflections to the listening position.

what is the mechanism by which a loudspeaker with wider polar dispersion than another is somehow "creating more physical reflections"?

You seem to be caught up on the semantics. I read "more reflections" and I what I really think "louder reflections." This is readily apparent if you look at the off axis SPL chart of speakers with different directivity patterns. The more directive speaker will have lower SPL levels off axis relative to the direct sound. For example, a very directive horn may be down by 20B at 8kHZ at 75 degrees off axis, while a very wide speaker may only be down by 8dB.

Edit:
Example. Revel Salon2 (Soundstage Network)

Klipsch R820F:

Note how the Revel is down about 8dB at 8kHz from 0 to 75 degrees off axis, while the klipch is down about 19dB by the same metric. The revel is radiating way more energy towards your side walls than the Klipsch, hence "more reflections" relative to the direct sound.

 

[DonH56]

but that still doesn't satisfy the claim that "more reflections" are created. you could state (as my original reply eluded to) that a loudspeaker with wider dispersion would have more mid/HF energy present off-axis which would change the spectral content of the first-order, sidewall reflection (even to the extent it could be perceived) - but a wider dispersion simply modifies the frequency content of that individual reflection. how exactly are "more reflections" created?

I'm not sure exactly your argument and I have not read back through the thread. My interpretation of "more reflections" is that a speaker that emits more energy to the sides will "create" more reflections than a speaker that directs all of its energy straight ahead. Seems like you are disputing the term "more"? Anyway, the picture below is my interpretation of the claim of "more reflections". I assume "more reflected energy at the MLP".

 

[RayDunzl]

Seems like you are disputing the term "more"?

Seems to be hung up on "create".

I'd exchange "create" with "excite".

 

[localhost127]

i did find here where toole agrees: https://www.avsforum.com/forum/89-s...evel-home-theater-thread-82.html#post57088076

i think it's an important distinction that wider dispersion doesn't necessarily "create more reflections" - instead it unmasks or energies existing reflections by adding to their bandwidth (particular in mid-HF) where the inherent reflections can be better perceived (for positive/negative subjectivity. but i disagree (as with toole) that wider dispersion somehow "creates more reflections".

to "create more physical reflections" requires a modification to the bounded acoustical space - or deployment of (for example) a reflection phase diffuser that would convert a single, sparse specular reflection into many reflections delayed temporally and dispersed spatially (and thus of lower gain).

or one could create an array of many flat/planar panels at different points on the sidewall to thus "create" additional sidewall specular reflections to the listening position. for those that seem to subjectively like first-order sidewall reflections, i'm curious why experimentation with this setup isn't discussed more.

 

[Trouble Maker]

But if a tree falls in the woods and no one is there, does it make any noise?

 

[Alice of Old Vincennes]

i did find here where toole agrees: https://www.avsforum.com/forum/89-s...evel-home-theater-thread-82.html#post57088076

i think it's an important distinction that wider dispersion doesn't necessarily "create more reflections" - instead it unmasks or energies existing reflections by adding to their bandwidth (particular in mid-HF) where the inherent reflections can be better perceived (for positive/negative subjectivity. but i disagree (as with toole) that wider dispersion somehow "creates more reflections".

to "create more physical reflections" requires a modification to the bounded acoustical space - or deployment of (for example) a reflection phase diffuser that would convert a single, sparse specular reflection into many reflections delayed temporally and dispersed spatially (and thus of lower gain).

or one could create an array of many flat/planar panels at different points on the sidewall to thus "create" additional sidewall specular reflections to the listening position. for those that seem to subjectively like first-order sidewall reflections, i'm curious why experimentation with this setup isn't discussed more.

Because it won't work.

 

[Alice of Old Vincennes]

But if a tree falls in the woods and no one is there, does it make any noise?

But if a tree falls in the woods and no one is there, does it make any noise?

I have been hearing a lot of noise lately, even though I try not be there. I refer to our reaction to lock down. Opened my eyes.

 

[Wombat]

But if a tree falls in the woods and no one is there, does it make any noise?

Leave an activated recording device there and take bets.

 

[localhost127]

Because it won't work.

what do you mean by "won't work", exactly? i'm referring to the modification of a room to introduce numerous "first-order sidewall reflections" vs the single sparse reflection that a bare wall would provide. has anyone actually tested this for subjective preferences or what data are you referring to to imply that it "won't work"?

 

[QMuse]

.. or deployment of (for example) a reflection phase diffuser that would convert a single, sparse specular reflection into many reflections delayed temporally and dispersed spatially (and thus of lower gain).

Such things are suitable for recordign/mastering studios, not for in-room listening.

 

[QMuse]

has anyone actually tested this for subjective preferences or what data are you referring to to imply that it "won't work"?

Yes, and most people stated such room treatment results in a "dead" sound when applied in listening rooms. Generally what you want in listening room is linearly behaving Topt with values betweeen 0.3 and 0.5 sec north of 100Hz.

 

[localhost127]

Such things are suitable for recordign/mastering studios, not for in-room listening.

that doesn't make any sense at all and is objectionably false statement. you have no authority nor data to insinuate that diffusion is only "suitable" for professional recording studios and mastering studios - of which "critical accuracy" perception of the direct signal is paramount and a design requirement (for properly designed/built spaces). a user may have requirements to build their home listening room to mimic that of an accurate control/mix/mastering room - and even go so far as to use the same studio monitor loudspeakers used in studios (such as JBL M2 Master Reference Monitor) in their home! what an absurd statement.

diffusion such as Reflection Phase Gratings convert slap-back echo, flutter echo, or sparse indirect specular reflection (ie, forms of acoustical distortion) into many reflections delayed in time and spatially dispersed (of lower gain). this in effect "hacks" the indirect sound-field in small acoustical space (home, residential-sized room) into that of what happens naturally in a large acoustical space reverberant sound-field.

diffusion gives a larger increase in perceived size of the space, envelopment, and spaciousness (IACC). it also provides a more even frequency response across a given area in 3space (less magnitude variations in the comb-filter interference pattern viewed from the 2d freq plot) because the superposed diffuse reflections are of lower magnitude, delayed (time, thus phase) vs a single, sparse indirect reflection. diffusers actually create MORE comb-filters, a positive trait as they are more closely-spaced and dense (vs the sparse comb-filtering that can impart negative trait).

"diffusion" is a way to modify indirect specular energy and is very useful in home listening setups (and even more-so in surround-sound/multi-channel home theaters that have a lot of active sources and thus a lot of "reflection points" for a wide range of listening positions). diffusion allows indirect energy to be maintained albiet at a lower level (where it is not cued on by the ear-brain for localization, imaging, intelligibility) being below the threshold - all the while not creating the "suck-out" feeling as when too much broadband absorption is utilized.

diffusers are a tool to modify a bounded acoustical space's indirect sound-field as presented to the listening position. also very useful for interior design (i myself have more reflection phase gratings in my home than most people's professional studios - it complements living perception just as diffuse lighting does).

 

[localhost127]

Yes, and most people stated such room treatment results in a "dead" sound when applied in listening rooms. Generally what you want in listening room is linearly behaving Topt with values betweeen 0.3 and 0.5 sec north of 100Hz.

your commentary leads me to believe you don't actually have any experience with reflection phase gratings or modifying a room if you think adding specular reflectors at side walls (to create many sparse reflections) or reflection phase gratings (to convert sparse reflection into many reflections of lower gain) somehow automatically result in a "dead" sound.