Why are closed cabinet speakers required to be away from the back wall?

Yes, and one thing I was asking is if AN generally has a minimum distance between the L and R speaker.

 

mids and high are not 360 riple waves. only LF frequencies are omnidirectional. mids and especially HF are highly directional.

it is not true that when a speaker is against the front wall, with very minimal toe in, that the front wall will reflects HF, this is physically impossible.
from about 1000hz and up, the front wall cannot reflect those frequencies.

the sides walls, ceiling, floor and back wall if not treated at the early reflection point are to blame here, not the front wall unless one use omni speakers.

I will repeat, only LF are omnidirectional and act as a 360 ripple. bass FR are emanated in a 360 ripple. mids and hf are directional. mids are a 180 ripple going forward to the listeing position and HF are very directional. the wall behind the speakers cannot affect the mids and hf, only LF.

Also, whats between the speakers, a TV for example, as long as its slightly behind the speaker line and the speakers do not have serious toe in, will not affect mids and hf at the listening position in a serious matter compared to the untreated room. a TV for example placed in between the speakers with the speakers slightly forward and minimal toe in, can only reflects LF, not mids and HF. its physically impossible. and a tv is so thin that its unlikely to have any or most certainly no serious measurable FR deviations in the LF.

 

there is a lot of BS when it comes to closed, ported, ect.

only issue is when you have rear ported speakers, if the port is 15 cm long, you must keep the distance between the port to the rear wall 15 cm long min.

all speakers, whether ported, closed, TL, all react the exact same way when it comes to LF. they are omnidirectional in the bass and brings all the same physical reaction in the room.

I believe that its marketing BS to say that a speaker work well close to a wall or not. fact is, every speaker, besides cardioid or omnidirectional speakers like MBL or panels, react the same way related to the back wall.

 

The Audio Note speakers are based on Snell designs from the 70s; the TL; DR version of their speaker placement web page is "wherever sounds best, or wherever you can put them". In an interview:

 

Audio Note believes that corner loading will allow the reflected wave to follow the direct sound closely enough so as not to be detected by the ear.

the "reflected wave"coming from the side walls, ceiling, wall behind the listening position and floor will affect the sound at the listening position. whether the speaker is corner loaded or not doesnt change the law of physics and how detrimental early reflections are.
corner loading certainly doesnt change at all the detrimental effects of early reflections.

such quote is what I call marketing BS. might convince people who dont understand room acoustic I guess

note: im not saying that corner loading or placing a speaker near the front wall do not have advantages, they do. they also have disadvantage though

but the effect of the front wall or corner loading is such a tiny part of the sound reaching the listening position that it is bs, misinformation and a lie to say that "corner loading will allow the reflected wave to follow the direct sound closely enough so as not to be detected by the ear."

 

Speaker cabins regardless of there design radiate energy, the cabinet the stand and anything thats near them will change the sound in a mostly negative way.

Just for fun, put them way our in the room temporarily, you should find them clearer, more detailed and less distorted. Less bass but more resolving bass.

 

This is really not the way it works except for in low frequencies, especially with conventional dynamic speaker. Mid and especially high frequencies are much more directional. They beam straight ahead, and they're either absorbed by whatever surface they encounter, or they bounce off whatever surface they're pointed directly at a bounce angle related to the angle of incidence.

So if your speakers are facing dead ahead with no toe in, some mids and highs might bounce directly off the wall behind you straight back towards the speakers and the wall behind them (which the highs in particular dissipating along the way), but if you have toe in the bounce angles of the specular reflections are going to occur at an angle and likely result in further bouncing off maybe multiple sidewalls before they reach that wall behind the speakers.

When it comes to mid and high frequency reflections, and especially highs, first reflection points of side and rear walls are going to have a big impact, in terms the time at which they arrive at your ears relative to direct sound, and in terms of comb filtering effects as they meet direct waves and other bouncing waves. but by the time they bounce past the speakers again and then off the rear wall and then back to your listening position again, they're extremely attenuated, especially the higher the frequencies.

Sound is moving around in your room at around 1130 feet per second, so the sound is bouncing all around the room, but typical there are a lot of redirections and lots of dissipation before high frequencies and even mid frequencies bouncing off the front and sidewalls get around to bouncing off the rear all at some angle of incidence, and then off more sidewalls, etc, before getting back to your ears. That's why I never quite understood the common audiophile placement of diffusion behind monopole speakers. That's gonna be enormously more effective at the first reflection points behind the listener (provided you have enough distance between your ears and the diffusors).

Ripple waves might be a good metaphor for bass, but for mids and especially highs, billiard balls bouncing of bumpers might be a better metaphor.

 

True that they all radiate (in different ways) but there are several speakers designed to be near-wall.

 

Not exactly true about higher frequencies being a ripple wave- however the higher the frequency the smaller the wavelength and the volume level off axis is reduced significantly. A wall directly behind the speakers still reflects mids and highs and can cause destructive interference. The wall essentially becomes a larger baffle for the speaker and unless they are designed for wall or surface mount application (i.e. baffle step compensation circuitry in the crossover) they will not sound as good as they could.

 

This is not my esperience at all. I had both front and back ported speakers in the same room, and they sounded totally different in terms of bass reflection. One was really boomy and one not boomy at all.

 

"When it comes to mid and high frequency reflections, and especially highs, first reflection points of side and rear walls are going to have a big impact, in terms the time at which they arrive at your ears relative to direct sound, and in terms of comb filtering effects as they meet direct waves and other bouncing waves. but by the time they bounce past the speakers again and then off the rear wall and then back to your listening position again, they're extremely attenuated, especially the higher the frequencies."

Thank goodness someone brought this up. I find FRP the biggest win. Bass and traps, not so much. Great thread!

 

First reflection points matter for mids and highs...but the biggest problems and the biggest impact from rooms is on bass and I would suggest bass fixes for every room and before first reflection stuff even, but there aren't many bass trap products that really work to well into the real bass range. But I certainly didn't mean to suggest that treating a room's first reflection points is in any way a substitute for dealing with bass response. Below around 150 Hz in a room without significant treatment, you're basically listening to the room as much as anything.

 

But that may be related to other things than where the port sits that makes a speaker boomy or not. A speaker designed to be close to the wall has a compensated frequency response in the bass as measured anechoic to compensate for wall support. If the speaker is designed to be free standing you have to compensate for the entire baffle diffraction effect, e.g. +6 dB in bass region.

 

what I explained to you, Chevrikas right after my post explained the same exact thing but better. sorry for my bad english. look at the better Chevrikas explanation.
if we are talking about early reflections, the wall behind the speakers cannot reflect HF due to the nature of the dispersion of a tweeter on a speaker baffle.same with mids, mids are not omnidirectional but directional; therefore the wall behind the speakers have no effect on the mids and hf reproduction.

only bass frequencies are omnidirecitonal and act as "360 ripples"

cheers

 

what are the bass trapping used in your room?

 

Stand on the side of your speakers and notice that you hear much more than bass frequencies.

 

there exist two "types" of reflections
early reflection and secondary reflections.

early reflections are reflections that are not -10db within about 20 ms at the listening position. Those are only the reflections that have been shown to be detrimental and "smear with the signal"

secondary reflections are actually not problematic because they are not very loud, they will not smear the source (signal coming from the speakers). LEDE designs are actually acoustic rooms built to bring back secondary reflections at the listening position.

secondary reflections are not problematic and will not smear the signal.

when you are behind your speakers, and hear "more then bass", what you hear is the secondary reflections. what matters is how those reflection will arrive at your listening position. when you stand on the side of your speakers, the direct sound will be the bass and some low mids. if the speakers would be outdoor, 10 meter away from the ground, youd probably still be able to hear some HF, but the HF would be very very diminished compared to the bass and low mids. back in a domestic room, even if the monopole speakers will spread more then just bass and low mids directly, the hf that will be generated will become automatically secondary reflections because they are not loud enough in amplituvde, therefore not detrimental at all at your LP.

hope this is clear.

the front wall (behind the listening position) is the least problematic area with monopole speakers because if the speakers are facing forward with minimal amount of toe in= no mids and hf early reflections coming from the front wall at the listening position.

Hope this is clear

 

I have some commerical tri corner type traps ij part if two cornwrs and I have some really low rent giant cotton laundry bags stuffed with 18 inches or so of loose packed pink fluffy in ceiling room corners with about a 15" air gap behind em.. those are big and deep.....though in one odd ball place in the room there's no room for an air gap but I have 3" of rockwool in front of the diy bass trap. I also find that I can open some doors to adjoning rooms and flatten a circa 45 Hz peak somewhat.

 

There's no doubt that sound of all frequencies is ping-ponging around the room as it bounces off surfaces, also the radiation patterns of of midrange woofer and tweeter, while forward firing, aren't necessarily laser-narrow, as I said, and with sound traveling at 1130 feet/sec, it's happening nearly instantaenously. But for high frequency sound to bounce off the wall behind the speakers, it has to bounce off the walls the driver is pointing at -- which are probably behind you, and then bounce past your ears and past your speakers again, and maybe a bunch of sidewalls, first, then hit that back wall and then bounce back past the speaker again to get to your ears, and it's losing energy along the way. There's a ton of comb filtering and cancellation and wave interaction between the direct radiating sound and the sound bouncing around between the speakers and whatever's behind and around the listening position, long before and at much greater energy that what's traveling back to the wall behind the speakers and bouncing back from there to your ears, obviously also more especially the greater the distances between the speaker and listener and room boundaries. If you're in a small room and the speaker are right against the wall behind them and the listening position has a wall right behind it, sound ping ponging back and forth may be much more obviously destructive.

 

Yes there are,but they are very few and far between.Only ones i heard were awful.

 

Have you heard Guru QM10 or Junior?

Guru Junior review

 

Haven't even heard of it,are they available on this side of the pond?

 

I don't think today but if I recall correctly they were available in the North Americas previously.

SonicFlare - Hi-Fi reviews, audio events, show coverage, photos and more Guru QM10 Speakers Review by Robert Learner

 

This is an interesting theory as all the BBC-inspired speakers I've owned/ auditioned sound better with plenty of boundary distance. In fact, all speakers I've owned sound better away from the walls. While it does usually limit some bass extension, it almost always results in higher quality bass, and always results in better imaging and cleaner highs. This applied to all my speakers, whether rear, front ported, TL, or sealed.

Acoustic Sounds, who sells Harbeth, ATC, Spendor, Stirling Broadcast, and Epos (and used to sell ProAc) also places their speakers away from the walls for best performace. This is why I have to disagree that most British speakers are designed for smaller rooms. Until recently, Spendor only quoted anechoic response limits in their literature. This still leads many to incorrectly assume a lesser bass response than their competitors -- by as much as 20Hz. This would be a very odd practice for a brand of speakers intended to have boundary reinforcement.

I currently have Spendors in a rather large room, especially by European standards, and best performance still results from >3' distances from all walls. However, the walls are backed by concrete on 3.5 sides, so that is somewhat similar to European construction.

I have yet to try AN speakers in my room, but the couple of pairs I've heard were using the corner reinforcement and I couldn't help but think their soundstage would improve if moved away from the walls. They reminded me of Heresys in that regard, in that they imaged well despite being close to walls, but the soundstage was on the shallow side.

As bass heavy American speakers are concerned, I suspect it's more attributable to culture than home construction. We were the first to start stuffing 15" woofers into the hatch of a CR-X, and adopt boomy home theater systems. Half the concerts I've been to were ruined by excessive bass, but it seemed I was the only one bothered by it. The pop songs that top our charts are often those with deep (and excessive) bass synths. It seems to me that many Americans simply prefer bass volume to bass quality. That even goes for some of our loudspeaker design engineers.

 

And to that end many speakers are made to cross over from audio to A/V,hence the use of big boomy baskets.Not a good thing for us audiophile bums.imo