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AR3a Directivity


Zilch

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Hi Zilch,

Can you explain the inboard and outboard directions? You'll probably need to explain the look of the curves below 200.

It would be interesting to see measurements that followed the exact angles that Allison published.

Grilles on?

David

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Conclusion:

This vintage sample AR3a has nominal 150° (-6 dB) horizontal beamwidth through the midrange, stepping to a substantially narrowed 90° at 10 kHz and further diminishing to 60° in the top octave.

There is significant asymmetry in the range of 1 - 2 kHz generated by an outboard null.

Generally, the response is chaotic, but the trends are clear.... :unsure:

Normalized wavelet transform:

post-102716-1276569930.jpg

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Can you explain the inboard and outboard directions? You'll probably need to explain the look of the curves below 200.

It would be interesting to see measurements that followed the exact angles that Allison published.

Grilles on?

Upright, the tweeter is on the left; outboard is left of there.

HF is at Max, and mid at Mid.

Data below 212.39 Hz is an artifact of the quasi-anechoic MLS calculation and invalid; the measuring distance (44") and time window limit reflection-free resolution to that frequency.

No grilles, and no battle about whether they're the "right" stuff.... :unsure:

These two plots tell substantially what it is:

http://www.classicspeakerpages.net/IP.Boar...ost&id=5664

http://www.classicspeakerpages.net/IP.Boar...ost&id=5669

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Discounting Dave's brief question and my comment here, this appears to be a one-man thread, Zilch.

Did you ever bother to set up the pair and listen to them in a good room with good recordings? I ask this, because how they perform subjectively will tell you (and if you bother to comment about how they sound, us) if the data you have above means anything worthwhile.

Howard Ferstler

Still soaking in. Whats with them colored wisps of smoke?

David

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Did you ever bother to set up the pair and listen to them

I think Carl and Dave are the only ones here who have ever tried to describe what a measurement actually sounds like (or conversely, what a described audible characteristic looks like on a chart), and I think it's something that is lacking in most of the discussions about measurements we see on CSP.

I agree with Zilch that someone's subjective listening preferences are of little value in attempted technical discussions, but a table listing different measured characteristics (diffraction, reflection, lobing, suckout, etc.) and a description of how each may affect sound (for example, "an X dB <something> at Y Hz will cause a bass drum to sound boomy") would be very useful in any attempt to try to objectively quantify the subjective listening experience for readers who are not pros (and maybe even for some who are).

Assuming, that is, that anybody here actually knows what all the measurements they're constantly battling over actually sound like. I know I don't.

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The data is well correlated with that presented by Allison and Berkovitz's Figs. 6 & 7, even though those were measured in a 2-Pi environment, well enough that it's easy to see which is inboard and which outboard in comparison to their original work 40 years ago, and though I have presented it at three times the resolution over a 20% wider beamwidth. Modern analytical methodology "sees through" the hash and extracts the directivity information where the author(s) merely observed:

It is difficult to assess performance because the output level changes rapidly not only with frequency but with small angular increments as well.

While this work comprises an ideographic representation of but one sample, the impacts of driver interference, reflections, and diffraction upon the measured performance of AR3a are clearly shown, and the presence (or absence) of the outboard null I have discovered here may be easily verified by anyone with measurement gear.

I have met Carl's challenge, indeed, exceeding it by a substantial margin. How it sounds is not my job. I will likely turn them over to a renowned authority on this forum for a private assessment, but know in advance that, if prior experience is any indication, he won't tell either; you'll have to do that yourself.

In the meantime, repeat the subjectivist mantra:

"FORGET the measurements, trust your EARS -- it's the MUSIC, stupid!"

:D

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How it sounds is not my job. I will likely turn them over to a renowned authority on this forum for a private assessment, but know in advance that, if prior experience is any indication, he won't tell either; you'll have to do it yourself.

Ship them down here, I'll be happy to. Can't promise you'll get them back, though. :D

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Still soaking in. Whats with them colored wisps of smoke?

In the wavelet? Reflections, generally. The most significant ones are likely to be those occurring within time windows associated with the drivers and cabinet themselves, i.e., the first millisecond or so. I can blow that up with higher resolution, and also vary the Q.

http://www.audiomatica.it/download/audaesny2007.pdf

[The mic stand and my beer are clearly visible to the trained observer.... :D ]

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Assuming, that is, that anybody here actually knows what all the measurements they're constantly battling over actually sound like. I know I don't.

Open these two links in separate tabs and toggle (click back and forth) between them:

http://www.classicspeakerpages.net/IP.Boar...ost&id=5664

http://www.classicspeakerpages.net/IP.Boar...ost&id=5676

That's how they sound, comparatively.

Gee, Zilch, do you ever listen to any of the gear you get hold of and measure? One wonders why you appear to be not the least curious about determining corelations between what you measure and what the stuff sounds like. It is one thing to be suspicious of individuals who do nothing but listening when evaluating components, at least if they do no level-matched comparing as part of the process. However, to do nothing but measuring and then do NO auditioning at all to see if the measurements mean anything seems downright odd.

I know how they sound TO ME.

I also know that is largely irrelevant with respect to how they might sound to someone else.

[There are people who have made careers of pretending to have insight in such matters.... :D ]

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I know how they sound TO ME.

I also know that is largely irrelevant with respect to how they might sound to someone else.

[There are people who have made careers of pretending to have insight in such matters.... :D ]

Z-

There are numerous posts where I have gone to great lengths to attempt to describe how my 9's sound to me, or how my 3a's or my 11's, or my LST-2's, or my Connoisseur 50's or my 2ax's or my Dad's 4x's sound to me.

I don't know if I have successfully or accurately described their sound, but it was my intent that Forum readers would find my comments at least somewhat interesting. This is, after all, the AR section of the CSP. (Well, ok, it's the Kitchen, not the AR section, but you get the idea.)

It's enjoyable to read other peoples' listening impressions. It's not anyone's "job" (this is a hobbyist site, not a professional site, and I presume even the Pros are here for their hobbyist interest in vintage speakers).

I'd love to know what your listening impressions are of the 3a's. We all know what their design shortcomings are (some of them philosophy-caused, some of them because the SOTA just wasn't as advanced in 1967 as it is today), and we similarly know what their design strengths are.

But exchanging views on how we feel they sound is half the fun. Don't cheat us out of your half.

Steve F.

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Lets be honest guys. If anybody gave a subjective account that was less than glowing then there would be the usual huffing and puffing about bias, lack of musical taste, poor room acoustics etc.

Is it worth it?

David

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As a diehard objectivist, what I do is about speakers, not about me, and it's an essential distinction I strive to maintain and teach by example.

I appreciate others' interest in the "me" part of this, which I believe is apparent in what I do. There are simply not enough available resources for it to be otherwise -- I have windows to eight forums open here all day, every day, supporting participants in the primary effort.

The work I have presented in this thread is not insubstantial, as those familiar with it will likely attest; it's up to others to do their part.... :D

Lets be honest guys. If anybody gave a subjective account that was less than glowing then there would be the usual huffing and puffing about bias, lack of musical taste, poor room acoustics etc.

Is it worth it?

I have been invited to leave several times over the course of these past years, despite never having expressed an opinion.

[Very recently, we ALL were, in fact.... :P ]

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As I have previously stated here, my mains were designed by our very own Speaker Dave 30 years ago. I have two pair each of 4430 and 4435. They were the first constant-directivity monitors available commercially and use a unique horn by Keele to accomplish that.

There are easily 100 pairs of speakers or more in the ZilchLab collection; I do not have a list or any inclination to compile one. :D

[Yes, technology has advanced, but at heart, I am very much a traditionalist. :P ]

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Lets be honest guys. If anybody gave a subjective account that was less than glowing then there would be the usual huffing and puffing about bias, lack of musical taste, poor room acoustics etc.

Is it really that hard to describe sound without preferences?

If someone posts a description of the funny noise their speaker is making in the AR forum there are any number of members willing to offer their view that it's being caused by a rubbing voice coil, damaged spider, too much or too little stuffing, etc. Why is it so hard for people who work with speakers for a living and presumably have listened to them a great deal to describe what diffraction, suckout, lobing, high frequency rolloff, etc., actually sound like without it being a "subjective account?"

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Is it really that hard to describe sound without preferences?

Why is it so hard for people who work with speakers for a living and presumably have listened to them a great deal to describe what diffraction, suckout, lobing, high frequency rolloff, etc., actually sound like without it being a "subjective account?"

A good question but isn't it subjective by definition? (As in, it isn't objective so it must be subjective.)

You can certainly try and describe a speaker in neutral terms rather than sneering at every minor fault you might detect. I think the problem here is the divide between those that like an old speaker, warts and all, and others that revere it. It is hard to be what I would call objective, without others crying foul and bias. Zilch can give legitimate measurements and some will cut down their meaning or worth. How could he describe the sound of a speaker (assuming he was so inclined) without ruffling feathers and opening himself up to even more criticism.

Regarding professionals describing the sound of speakers, yes all the pros I know can sit and listen to a speaker and describe "the sound" afterwards (okay, some a little better than others). There is generally a whole lexicon of descriptors for this with the majority of them describing frequency response effects. Wooly, muffled, bright sizzle, shouty, thick, boxy, soft, sweet, hard, fast, slow, "aw" sound, "eh" sound, "oo" sound, murky, heavy, projecting, megaphony, nasal, recessed, dark. Most engineers I know whould pretty much know what you were talking about if you used such terms. Others will just verbally draw out the frequency response, as they perceive it. "Up a couple at 3k", "week in the middle hundreds","soft at 5k". Others describe the effect related to instruments: "makes the piano clangy", "everything sounds like an oboe","harsh on strings", "vocals lacking body".

JG Holt was one of the pioneers in this. His early Stereophile loudspeaker reviews are very educational.

David

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I have no pointed opinions about AR3a -- others want to know about them, and so do I; I measure them and post the data, is all.

We've been speculating and blathering about AR3a directivity on a theoretical level for two years. There it is, for this one example (I have more), on this axis, as I measure it, for what it's worth, for others to think about and discuss, to measure themselves and compare, to reference, criticize, or whatever floats their boat.

If somebody asserts that the exquisitely wide dispersion of the AR3a tweeter has never been bettered, they're gonna have to put forth some IN SITU empirical data as evidence substantiating that, 'cause, at least insofar as this particular one is concerned, I easily bettered it with a cheapo modern waveguide, substantiating earlier work by Carl posted here.

Dismiss it if you like, but I'm about to become a subscriber to Gene's theory that the success of the LvR promotional demos was in part attributable to the festival of phase interferences so clearly in evidence here. That's not opinion, and not ridicule, either, rather, FACT, up to each of us to reconcile to our own satisfaction.... :D

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