Near field - mostly the whys and not much of the why nots and my system.

[Dr.W]

In this thread Greg and Neil made "fun" of my hearing boo hoo, AND said 95% of the sound from my panels were running smack dab into each other. NOT.

http://www.whatsbestforum.com/showthread.php?54-The-backwave-is-dead.Long-live-the-back-wave./page2

Don't worry I know some of the comments were made in jest. But......................

First to disparaging comments about my hearing, my spouse who is 10+ years my junior is beginning to have problems in that area. While, as a 63 year old male, my high frequency hearing has declined from my teenage bat hearing days, I still hear quite well up to about 14k. Above that I really have to crank the volume on the test tone to hear much. Beyond 16k it is pretty much gone. However, my overall hearing sensitivity is very good. I can hear very quiet events at home and at work that many much younger people seem to miss. So, no, not deaf, or going that way soon from my listening habits.

I do listen fairly loudly when I am enjoying my stereo, generally around 88 to 90 db. Most of my listening sessions are around an hour to an hour and a half. Some tables list two or more hours at 90db as having the potential for long term hear loss.
Just because one is sitting close to a speaker does not mean it is too loud. The gain control is a valuable item. Because the sound intensity falls off by 6db with each doubling of the distance, were I to sit 12 feet from the speakers I would need 12db more output from my amps to get the same sound intensity.

Of course we all know that for every additional 3db of output we need twice the power from the amp. If I am playing at 2 to 10 watts RMS, per channel (rough guestimate) for my current listening position to achieve 90db, then the amp would have to produce 32 to 160 watts at 12 feet. That is not a problem for amps that are rated at 550/channel into a four ohm load (nominal for Prodigy) and around 1,100 per amp bridged.

But what is going to happen to the musical peaks/transients that are 10 to sometimes 100 times the RMS power? They are going to clip!

Now one may not hear that clip as distortion, but one may very well hear it as “not as real” or “not as musical” or “not as sweet”. So this is one of the benefits of near field listening, considerably more headroom in the system.

Near field listening has some GREAT advantages and a some disadvantages.
More to come.........

 

[amirm]

I am fan too for my everyday listening in front of the computer. As you imply it is easy to go all out in near-field and get proper amplification due to low losses.

 

[Johnny Vinyl]

Hi Bruce,

I'm about to move into a larger apartment and am dedicating one room (about 9x10) for a somewhat vintage analogue setup. I'll be using a rather low-wattage (30wrms) Rotel power amp/preamp combo, and my speakers are unfortunately not the most effcient (Totem Sttaf's). Would it be good idea to implement a near-field setup under such conditions and restrictions?

John

 

[JackD201]

Hey there Bruce! When I hunted down your system pics I was shocked. I'd NEVER seen anybody even try such a configuration.

All I can say is that if it works for you, keep on chugging Doc!

 

[Gregadd]

All kidding aside Doc W. Well not all.

Let's make an analogy with tv. Can we agree that there is a point where the picture will looki ts best. the picture is composed of little color dots on a black background. The tv depends on our ablty to fill in certain gaps. For the most part it is part reality and part illusion. If done right, when a person throws a punch he need not actually strike the person. He need only swing very close. Your eyes will do the rest. It's like proofreading. I miss things because my mind filled in the missing word. Or my mind actually corrected the spelling. Get two close to tv and those gaps become exposed. You also lose depth of field and there has to be a certain eye strain.

At your position noise is highlighted. Most speakers have different frequencies eminating from different drivers or different areas of the panel. I think there is a point where the different waive launches blend together creating a cohesive stereo image. If I rise from my seat and put my head close to or against the speaker the image collapses and a certain frequencies are diminished or highlighted. A lost also occurs if you move to far away.

The good thing is Bruce. when I get the time I can duplicate your listening position. All I need then is a honest report on what I heard.

 

[amirm]

All kidding aside Doc W. Well not all.

Let's make an analogy with tv. Can we agree that there is a point where the picture will looki ts best. the picture is composed of little color dots on a black background. The tv depends on our ablty to fill in certain gaps.

I don't think that analogy works. I will write an article on this later but for now, the reason the eye fills in the details is simply due to low pass filtering and nothing magical or perceptual. The notion of hearing a 3-D effect though with two speakers, works on an entirely different principal. So if you meant to say this figuratively, it is fine but not literally .

 

[Gregadd]

I look forward to your article. But I've seen commercials on this principal. I've also taken a magnifying glass to the TV and seen the dots. Why it fills in may be some principal of which I am unaware. Just curious. Where is the low pass filter? In the TV, in your eye or, in your brain? The point is it works best at a certain distance, Albeit on different principals. The image and sound from the CLS shifts dramatically when I sit back or lean froward. Moreover my TV recommends an optimum seating distance for best picture.

 

[Dr.W]

Greg,

Have you noticed that the recommendations for distance to screen have decreased with higher resolution monitors?

Screens of the same size with 480i, or 540p, or 720p or 1080i and 1080p all have different recommended distance. The smaller the "pixels" the closer one can sit and enjoy the additional resolution of high def. Then one can truly get big screen results from a smaller one while using "near field" watching.

Greg come on over and listen.

Bruce

 

[amirm]

Where is the low pass filter? In the TV, in your eye or, in your brain?

In your eye. Its high frequency (resolution) rolls off just like any other optical recording system.

Moreover my TV recommends an optimum seating distance for best picture.

The rule of thumb recommended by them and many others on the Internet is an oversimplification. I will detail what is going on later in the article.

 

[nsgarch]

I do listen fairly loudly when I am enjoying my stereo, generally around 88 to 90 db. Most of my listening sessions are around an hour to an hour and a half. Some tables list two or more hours at 90db as having the potential for long term hear loss.

Bruce, If the small portion of the panel which, in your setup, your ear is actually "hearing", was producing an 88 to 90 dB SPL, your speaker would have blown up long ago. My guess is that when the whole panel is producing 90dB, the portion right in front of your ear(s) is producing a SPL of maybe 20dB, or even less.

Just because one is sitting close to a speaker does not mean it is too loud.

Well, that really depends on the kind of "speaker" we're talking about, doesn't it? Compared to your listening to maybe 2 sq.ft. of your 12+ sq.ft. Prodigy panel, if you were sitting a couple feet in front of say, a JBL 365 compression driver playing at 90dB SPL, you could just kiss your hearing goodbye!! With your setup, as I said above, I don't think you're subjecting your hearing to anywhere near the SPL you imagine.