Near field vs. far field, or why AR's don't "rock"

[Guest postjob62]

First, a word of thanks- I'm new here, and I'm constantly astonished at the body of knowledge and the willingness to help, not to mention the general lack of acrimony. Thanks to all.

Forgive me if I'm wrong and am combining two unrelated topics in one post, but I thought these things might be related.

Can anyone outline for me what is "near-field" listening as opposed to "far-field" and how it relates to AR speakers, especially the early single-digit ones?

Secondly, and hopefully related, why is it that AR's (again, especially single-digit) are reputed to not be well-suited to rock 'n roll? That's about all I listen to, and I couldn't imagine it sounding much better than on my 4x's or my 2ax's. Of course, I guess it's what your'e used to...

Thanks,

Ed

[Steve F]

The near field vs. far field debate is really the on-axis vs. energy response issue. This has been addressed at length by myself, Tom Tyson and others. Here is the link info from an earlier post of mine:

>>There are several excellent posts in a thread entitled "EV vs. HK Design Philosophy." EV of course was Ed Villchur, and HK was Henry Kloss, of AR and Advent respectively. The thread is dated from December 11, 2002, and Tom Tyson and myself have several long entries (#’s 1540, 1541, 1542, 1546, and 1552), as well as several other excellent entries from Forum contributors. This thread will give you a very comprehensive and accurate picture of the different ways that AR and Advent designed and marketed their products.

http://www.classicspeakerpages.net/dc/dcbo...&mode=full#1541

>>>>>>

As to the rock music issue, this has much to with recording and mastering techniques and practices and the use of studio monitors with response irregularities. There were several excellent exchanges on that topic as well, which I'll try to locate for you.

Steve F.

[ninohernes]

I listen to all kinds of music, including rock, and my AR-2's, AR-3a's and AR-4x's all do great with rock! Actually, I enjoy listning to rock on AR speakers more than any other. They can really pound out the low end at high volume levels with very little distortion.

[Guest Bret]

>Secondly, and hopefully related, why is it that AR's (again, especially single-digit) are reputed to not be well-suited to rock 'n roll?<

Because you can actually hear what it sounds like?

But seriously folks. . .

I suppose if you are going to listen for three minutes and twenty seconds you could get away with a much peakier speaker that just goes "whump whump whump" and screams real loudly.

Like a Cerwin-Vega.

Oh sure, Ted Nugent playing "Freeforall" sounds good on a pair of 3a's, but on a pair of big Cerwin-Vegas with the same sized amplifier, you can demolish derelict buildings, alienate bothersome neighbors, frighten women, children, and small furry woodland creatures for hundreds of yards in any direction.

I have no quarrel with the way Black Label Society sounds on any of my ARs and I DO have a quarrel with the way Crosby Stills and Nash sound on a pair of Cerwin Vegas.

Bret

[soundminded]

Steve, thank you for referencing this fascinating thread. The way different people approached the same problems and what the results were in retrospect made for great reading. I'm sure those issues will be discussed here again and again.

[kkantor]

To be really technical, here is the "proper" definition of near- and far-field:

Imagine a speaker in room. Very close to the speaker, what you hear is dominated by sound waves that eminate directly from the speaker. Far from the speaker, what you hear is dominated by reverberant sound, that has bounced around the room a bit.

At a certain distance called the "critical distance," the sound power balance between direct and reverberant energy is exactly equal. This can be measured, but it is more often calculated, based on the reflective characteristics of the room and the directivity of the speakers. Since these factors change at different frequencies, in a strict sense, the critical distance varies over the sound spectrum. Anywhere closer than the critical distance, at a given frequency, is "near-field," and vica versa.

In recent years, the terms near- and far-field have come to mean not only where you are listening, but also where the speak designer expects you to listen. In other words, a "near-field monitor" is one that is designed to be listened to up close.

The rock and roll issue is so complex it is isn't funny. A good part of it relates to marketing hype. Efficiency. Directivity. Early reflections. Power spectrum. Driver reliability. Studio reference monitors. Suffice it to say that the subject defies reductionism, but that there are many classic AR's that can rock with the best of them.

[Guest bocoogto]

Vintage AR speakers such as the AR-3 are not very efficient. Sound levels associated with rock music cannot be duplicated with these speakers, even though they are very accurate compared to nearly all the more efficient speakers of their day.

Klipsch had an ad showing a stack of AR's needed to match ONE of their corner horn systems. The ad stated it would take 89 AR speakers to match the output level of one Klipschhorn system. Based on the efficiency--AR's at about 89 db for one watt input versus the Klipsch's at over 100 db for one watt--this was a true statement by Klipsch.

In my home, I'll take the lower efficiency gladly as a trade-off for accurate sound. I once had a stack of two AR-3's and one AR-2a on each stereo channel. Each speaker was driven by its own tube amp--Four McIntosh MC60's and two Dynaco Stereo 70's in mono mode. The furnace didn't run very often when the system was on!!

[Guest postjob62]

Bonestock,

I'm in agreement about the accuracy trade-off.

What puzzles me is the volume and perceived loudness issue you mention referencing the Klipsch ad. I like my classic rock, well, loud! And I find that my 4x's and 2ax's, both I assume notoriously inefficient, give me all the volume I can handle in moderate (13x13.5) and somewhat larger (19x20) rooms *even* when driven by moderately powered (30-50 wpc) 70's era Marantz and Pioneer SS receivers. I honestly don't know how much louder I could take it, and as I mentioned, I like loud.

I'm don't mean to sound overly defensive of "our" speakers, I just don't exactly understand the reputation and am curious. I would like to research and find out more about the circumstances Ken mentions in his post above.

Ed

[Steve F]

A lot of this can be explained by the fact that what’s considered “loud” is actually pretty easily attainable by most amp-speaker combinations in virtually all real-life situations.

First, consider that the sensitivity specification, as measured one meter on axis for a 1-watt input, will yield a figure of about 86dB for an AR-3a. That’s considered “inefficient.”

But 86dB is really a pretty healthy level, more than background listening. It may not be loud enough in a dealer showroom, but in your quiet living room, you’d have to turn it down to answer the phone.

Now, you got two speakers, so there’s some addition to the 86 SPL figure because of that. You are also about 8-10 feet away from the two speakers (and somewhat off axis, to boot), so there’s some reduction because of that (the inverse square law, and all that stuff). Throw in your room’s absorptive characteristics, any open walls that lead to the next room, etc, and what you’re left with is that the raw sensitivity figure for one speaker is a pretty decent number to work with as to how loud two speakers will sound from your listening position. There are a LOT of variables, obviously, but 86dB for 1 watt for a pair of 3a’s from your listening chair is not a bad estimate.

Every doubling of power is another 3dB of loudness. So:

2 w = 89dB

4 w = 92 dB

8 w = 95 dB

16 w = 98 dB

32 w = 101 dB

64 w = 104 dB

128 w = 107 dB

256 w = 110 dB

I’m not even sure how cleanly the 3a can play at or above 110dB, but any competent amp has enough juice to push the 3a to 95-100dB in a normal living room. And that is very loud. That’s why you don’t have any trouble getting the 3a as loud as you like it with a normal amplifier.

As to Klipsch’s claim of super efficiency being such a virtue, it was once pointed out to me that many amps’ distortion and s/n ratios improve markedly above the fractional watt level, and that running an amp past 1 or 2 watts may actually put it into an operating zone where its THD and s/n are a much lower percentage of its output than is the case at 1/4 watt. Something to ponder.

In any event, since the 1970’s, clean wattage has not been expensive, so ARs and other low-efficiency speakers can achieve completely satisfying loudness levels in the home without any difficulty. High efficiency by itself is certainly not the prime determinant of speaker quality.

Steve F.