Ah the confusion! Vaccy there is a diiference between the acoustic near field and what are called near field monitors.
In acoustics there is a concept called the reverberant field. When you are in a room of enough size that there is a classical concept of reverberation (basically enough sound bouncing around you don't here it as echoes) as at some distance from the sound source all you really hear is the bouncing sounds or just the reverberation.
If you take a sound level meter and walks round the field the level does not increase. In a true reverberant field the direct sound still being created is less than what is still bouncing around.
At some point if you watch the sound level meter as you approach the sound source the level will begin to rise. When the level rises by 3 dB that means that half the energy is from the reverberant field and the other half is from the sound source. That point is called the critical distance.
The critical distance can vary with frequency as reverb levels vary with frequency. Highs are absorb more than lows but lows also require more distance between walls to be able to bounce freely and become reverbetation rather than an echo. (Echo is usually a single or discrete bounce. Reverb is any more bounces. When ray tracing I look at the first seven bounces where possible.)
The area from the critical distance to the sound source is called the near field.
For adequate speech intelligibilty you can be as much as three times the critical distance in large or reasonable dead rooms. The exact distance and how to extend it is where I make my living.)
Now a near field monitor loudspeaker is meant to be used up close and only in the near field.
So the title is confusing. That kind of loudspraker does not extend the near field in a given room as does a more directional loudspeaker.
Today's project was a gymnasium at a church. The critical distance was under 10 feet. The distance from the loudspeakers to the back of the audience is 70 feet.
One solution would be to use multiple long throw loudspeakers and signal delays. More loudspeakers than expected would be required as multiple sources also add reverberation. The practical solution was to add sound absorption in critical locations. Done by church members under $1,000.00!
Or as the large scale acoustical wisdom says "First you treat the room..."
The M2 owner's manual at JBL's website shows a minimum suggested listening distance of 46", with the speakers toed in towards the listeners's ears. A common near-field listening distance may be around 36".
The idea with near-field listening is to have the monitors far enough away so that wave fronts from various drivers can combine into one insofar as perceived by the listener. Yet speakers need to be close enough to the listener so that room reflection effects are kept minimal, and so that HF attenuation with distance is not problematic.
If seems like a 46" distance from some speakers might be workable for near-field use depending on the room acoustics where they are located.
As to the particular speakers in question, it's seems easy to imagine that listening to a pair would be very interesting. Haven't had the opportunity myself.
Aside from questions about the speakers, maybe what seems to be pushing some buttons is RNM's take-or-leave-it-attitude about his posts. It seems like there may be some history to the forum in which posts are subject to being "called out" for justification when claims are disputed by others. Despite the appearance of some possible tradition in that regard, it doesn't seem to be something spelled out in the rules.
The idea with near-field listening is to have the monitors far enough away so that wave fronts from various drivers can combine into one insofar as perceived by the listener. Yet speakers need to be close enough to the listener so that room reflection effects are kept minimal, and so that HF attenuation with distance is not problematic.
If seems like a 46" distance from some speakers might be workable for near-field use depending on the room acoustics where they are located.
As to the particular speakers in question, it's seems easy to imagine that listening to a pair would be very interesting. Haven't had the opportunity myself.
Aside from questions about the speakers, maybe what seems to be pushing some buttons is RNM's take-or-leave-it-attitude about his posts. It seems like there may be some history to the forum in which posts are subject to being "called out" for justification when claims are disputed by others. Despite the appearance of some possible tradition in that regard, it doesn't seem to be something spelled out in the rules.
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Jan,
FYI in nursing homes and similar institutions old geezers who get mean and cranky are often tested for a low level infection that cause pain and the resulting bad attitude, pickin fights for no reason etc. Just saying...
Bill,
When you stop learning! Of course it could be Altzheimers!!!
FYI in nursing homes and similar institutions old geezers who get mean and cranky are often tested for a low level infection that cause pain and the resulting bad attitude, pickin fights for no reason etc. Just saying...
Bill,
When you stop learning! Of course it could be Altzheimers!!!
Right now, and most always, I am listening though the same $300 speakers that Scott is listening to so happily. I am happy with these speakers too, for most listening. Of course, he got them wholesale from the manufacturer, just like I did. They might have retailed for $600 or more. However, these speakers are compromised overall, and there are better speakers (but of course they cost more)! Like autos, a mid priced Korean manufactured car is about all that anybody really needs to get to work, school, or the store, but some people still invest in sports cars and fast sedans. Why is because, if you can afford it, sports cars, etc are more fun to drive, if you like just to drive, without necessarily it being a necessary evil to get where you want to go.
Now, not everyone, either here or in the audio world has a lot of extra money to throw into hi fi. That is why DIY is so useful, and buying used equipment is another good and cost effective approach. That is what I do, besides designing my own amps and preamps.
I could not afford the speakers in my reference system, but they ARE BETTER than the MET7's that cost me $300 or so. Only when I want to listen to real music, do I turn them on. For TV and talk radio, the MET7's are just fine, and I can control them with a TV remote, very convenient.
Now, not everyone, either here or in the audio world has a lot of extra money to throw into hi fi. That is why DIY is so useful, and buying used equipment is another good and cost effective approach. That is what I do, besides designing my own amps and preamps.
I could not afford the speakers in my reference system, but they ARE BETTER than the MET7's that cost me $300 or so. Only when I want to listen to real music, do I turn them on. For TV and talk radio, the MET7's are just fine, and I can control them with a TV remote, very convenient.
Jackob: Thank you, I couldn't find any picures of the rear so was confused over how they managed the pattern control
Ed: I hope never to stop learning. Remembering is my problem at the moment, but not yet Alzheimers just lack of sleep. Gimmie a year and I might be back to whatever normal was (can't remember
)
Scott: I call foul as you have a phono stage designed by a world renowned expert that would have a retail price of about $2000
Ed: I hope never to stop learning. Remembering is my problem at the moment, but not yet Alzheimers just lack of sleep. Gimmie a year and I might be back to whatever normal was (can't remember
)Scott: I call foul as you have a phono stage designed by a world renowned expert that would have a retail price of about $2000
Sure Ed, I know that and you know that I know that. Always good to hear about your projects in detail. I envy the size of the toys you play with and would love to spend some time on your job with you..
1. Not at all . I had learned and applied critical distance and near field listening 50 years ago. The M2 is my latest speaker system which does same. 50 years ago I also used JBL and the LE175DLH with 90 degree conical horn. And rear loaded horn for 15 inch D130 and a tweeter.
In the past I have owned Magnapan and ESL speakers and tri amped ESL system with stereo 18 inch Hartley's in rear loaded transmission line. All of these have low distortion, wide freq range and non wide angle coverage. I sit close to the speakers and not beyond the critical distance.
2. The M2 is the best and 4 feet is within the critical distance in my room. The preferred listening height is right between the two drivers -- where they placed the JBL badge. 3-4 feet is about the distance from the front to the back of large mixing console. And these ARE made for studio and home size environments.
THx-RNMarsh
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All good info... the details, I am not going beyond introducing the concept. Others can do their own home work. No sense in me writing a lot which is already in many books . The M2 was just perfectly designed for homes and studio room sizes (not church volumes etal) and allows me to listen in the near field and hear only (mostly) the recorded source as intended to be heard.
Thx -RNMarsh
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Ed's info is very good. It points out that textbook critical listening distance is invalid for the average size home!
Early reflections are of course a big problem, which is addressed by the M2, the Geddes speakers, dipoles, the kii as well as many others. Close listening can help there as well of course, but Earl's approach where the first reflection is off the back wall is to me a big step in the right direction.
Personally I'm interested in trying one of the 'synergy like' designs some people on here have done. Good directivity and point source down to around 100Hz
Early reflections are of course a big problem, which is addressed by the M2, the Geddes speakers, dipoles, the kii as well as many others. Close listening can help there as well of course, but Earl's approach where the first reflection is off the back wall is to me a big step in the right direction.
Personally I'm interested in trying one of the 'synergy like' designs some people on here have done. Good directivity and point source down to around 100Hz
For a one day event in Grace Cathedral in the late 70's, bucket brigade delays were still fairly uncommon and the best we could do for driving some toed-in Altec 604's staggered along the walls. For permanent installations such as a long arena room treatment was generally better. Some things don't change, although speakers sure have gotten a lot better.
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It would be interesting if there were a listening room somewhere to hear and compare some high performance home or studio speakers. For me at least, it's very hard to decide what to do in terms of looking at prospective speakers if it's only possible to read reviews and look at specs, many of which are lacking a lot of details.
Another thing that is somewhere between room treatment and speakers, and which does't seem to get much attention is speaker support. Some people go to great lengths to isolate speakers from floors, for example. For studio use, these things can be very helpful: Recoil Stabilizers | Primacoustic Yet, I haven't seen much discussion of the topic here. Maybe there was a thread at some point I missed?
EDIT: Bill, when is the next Burning Amp?
EDIT: Bill, when is the next Burning Amp?
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well most of us don't listen to speakers on a meter bridge, but mass+blutak is often used . Of course there are varying views and i have a pair of speakers with cones screwed in the bottom to decouple them from the stand. Funny old world
Good old Max Townsend of course has a solution www.townshendaudio.com Seismic Isolation Bars for speakers / sub-woofer - Townshend
Good old Max Townsend of course has a solution www.townshendaudio.com Seismic Isolation Bars for speakers / sub-woofer - Townshend
My NS-10s are sitting on some Recoil Stabilizers, which in turn are on some fairly sturdy speaker stands. The Stabilizers do help considerably as all the testimonials from famous recording engineers claim, but there is a lack of measured data to quantify whatever changes. However, providing measurements that would apply to different use cases in a meaningful way might be difficult. Part of the problem is that whatever speakers are sitting on can, by vibrating in reaction to the speakers, act as additional frequency dependent sound sources of unknown directivity and resonance characteristics.
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In all honesty, directivity and point source falls apart nearer to 1000 Hz than 100 Hz on all but the most enormous of horns. For the biggies, you're realistically looking more at ~800 Hz directivity.
No! There are clever designs that maintain good uniform directivity down to 150 Hz or so in rather compact boxes. (3') Not saying how as they have been on the market for a while and their direct competitors haven't noticed. But the pros have noted the increase in sound quality.
I just gave them an order in the low seven figures.
let me qualify that overly generalized statement.... I don't know which average size home we are talking about... American or European/Asian? Most speakers system used for home are wide dispersion designs. This reduces the critical listening distance and that distance is often not acceptable for most people --= who don't want their sofa only a few feet from the speakers. narrow dispersion can put that crit distance further away from the speakers. But how many home systems do you see which have narrow dispersion? Not many for sure. The panel type speakers can help. Other wise you have to use extensive room treatment and still not be as uncolored as near field. My living/listening room is large.... and I choose narrow dispersion speakers.... this places the crit distance further away. Together, I get a flat response at the listening position/near field even 10-12 feet away. Not messed up by room resonance/reflections, modes etc.
A flat freq response speaker - measured 1-3 feet away in echo free chamber is all messed up by the room..... unless you listen in near field and with narrow dispersion speakers. of course you can use typically wide dispersion speakers and spend a lot on room treatments.
With narrow dispersion -- minimum room influence results in same flat freq response at the listening position. No EQ was needed to get flat extended response. No extensive room treatment needed.
Freq Res at listening position using JBL M2; NO EQ used. Measured at 12 feet to sofa. :
THx-RNMarsh
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