AR-6 and 'classic' two-way speakers

[ra.ra]

In the early 70's, towards the end of the 'Classic' era, AR was producing four different two-way speakers: AR-7,4ax, 6 and 8. Never mind the AR-8 for this discussion - - - it had the 10" woofer and the larger cabinet size of the 2ax or the 5. But the other three models (6, 7 and 4xa) had the very same tweeter and an 8" woofer, albeit with different cab dimensions and crossovers. So I guess my first question is: exactly what was the marketing strategy behind this effort?

Despite the highly touted tweeter, AR's debut literature of the 6 highlighted the "unusual" woofer. Was this 8" woof different from the 7 and/or the 4ax, and if so, how? Did any of the incarnations of these speakers ever leave the factory with a fabric surround woofer, or were all 70's AR woofers of the foam version?

What are the manufacturer's original part numbers for these woofers and tweeters? Also, if I hadn't learned on these pages that there are no stupid questions, I would have thought this next one might qualify, so here goes: why is the AR-6 the only speaker of this era where the woofer location in the baffle board is so obviously off the vertical centerline (and so distant from the 'bottom')?

And then there is the tweeter. In the attached pics, there are at least three versions of tweeter installation: front-wired with black tape; front-wired with more robust wiring; and fully rear-wired, normally seen in the 'euro' version. Also, these pics show two varieties of rear wiring and HF control: 1) three wiring posts with rheostat potentiometer; and 2) two wire terminals with three-position switch. Still, I cannot figure this out - - - what is the correct crossover frequency? - - 1971 literature suggests 1500 Hz while 1973 literature states 1800 Hz. Lastly, do you AR-6 owners have particular preferences among these versions regarding build quality, audio performance, or ease of maintenance?

[michiganpat]

I'm by no means an expert, but the 7 fills the niche of small bookshelf, and it is significantly smaller than the 6 and 4x/4xa...the 6 was touted as having bass response similar to the 10" 2ax IIRC. it was also AR's first "modern" (read brighter) sounding speaker.

the 6 and 7 never had a cloth surround. I am unsure if they used the same woofer.

the tweeter was designed by roy allison, an it remained in production through the late 90's "rock partner" series. it is among my favorite tweets. it was also used on the 17,18,18s,18b,18bx,93,94,rock partners and others

[ra.ra]

Thanks michiganpat (my AR-4x's went to college with me in Michigan in '73 - - - and I still have them).

As I had assumed, cloth surrounds were passe during this phase of production. Just last night I located the attached AR-7 description which pretty much confirms your thoughts about marketing - - - AR had developed Allison's great little tweet and apparently wanted some market share of smaller bookshelf speakers. I do know that these speakers, comparatively, are tiny little guys, and this description almost suggests that the woofer may in fact be unique to this speaker.

I am still trying to ascertain the proper AR part numbers for this tweeter, and the woofers in the 6 and the 7. The model 6 seems to be the first of these three into production (1971?), and also the main focus of my search - - - I've become rather interested with the several permutations of this speaker within its 5-year production run. Also, I am trying to locate an AR-6 crossover schematic for the version with the three terminals and the Aetna pot. Does the attached pic describe the speaker I am asking about? Can someone confirm the coil number(s) and capacitor values (I do see 10 mfd on this box label)?

I am quite certain that much of my query can be answered within CSP discussion or library, but I admit to having some difficulty using the search function and archive material on this terrific site.

AR-7 description.pdf

AR 6 x-o.pdf

[Steve F]

For a while in the early-mid '70's, AR did indeed have three 8" 2-way speakers (the4x/4xa, 6 and 7). It was not good marketing on their part to do so, however. The 6 (intro'd in '71) was a superb speaker, easily outperforming the 4x at both ends of the spectrum. The very first 6's had a special woofer with, I believe, a multi-segment magnetic structure. The x-o was 1500 Hz. As a running change, the 6's woofer changed to a more conventional design, and the x-o went to 1800 Hz.

In late '72, the 7 was introduced to great acclaim. The 7 had a slightly brighter, more sparkling upper midrange than the 6 (which was not particularly "bright." If anything, it was criticized by local dealers in my area for being midrangy). The 4x (then the 4xa in '73-'74) continued on for some inexplicable reason. I have a feeling that AR probably felt that the AR-4-shaped cabinet and AR-4-ish model number had accumulated some 'marketplace equity' by that time (a mis-guided, never-true marketing error made by many companies in many industries, over and over), so it seems that AR was reluctant to discontinue it. The -4xa was a forgettable, redundant sales flop. A decent little speaker, sure, but its very existence was unnecessary. The -17 (4xa replacement) was nowhere near the seller that the -18 (7 replacement) was, either. AR should have dropped the 4 when the 7 came out and been done with it, saved their resources, and concentrated their promotional efforts on a more logical 8-inch 2-way lineup of two models, not three.

In a post of mine from a few years ago, I make this observation about the 7's unique voicing:

The AR-7 used the new 1 1/4" cone tweeter, introduced in the AR-6 two years previously. The 7’s woofer had a free-air resonance of 25Hz (same as the 6), mounted in an enclosure of .345 cu. ft. for a system resonance of 68Hz (compared to a system resonance for the AR-6 in its larger enclosure of 56Hz). Therefore, as a result of its woofer’s lower resonance, the 7 had very nearly identical bass response to the 4x, in spite of the 7’s cabinet being markedly smaller. Incidentally, a 25Hz free-air resonance for an 8" woofer is almost unheard of today. Most 12" OEM woofers used by the major commercial speaker companies nowadays have a free air resonance of 25-30Hz. I’d hazard the guess that there is currently not a single 8" woofer used in any low-priced speaker from a mainstream manufacturer that has a resonance anywhere near as low as the 7’s. It was really something.

The AR-7’s voicing was also different than the other 1 1/4"-equipped Classic AR speakers, the AR6, AR-8, and AR-4xa. In both listening tests and a review of their measured frequency response curves as published in High Fidelity magazine, the AR-7 can be seen to have 2-3dB greater output in the 6-8kHz range than the others, and this agreeable characteristic imbued the 7 with an extremely alluring sonic signature from an almost impossibly compact package. (Whether the voicing difference was intentional or simply the result of a slightly different interaction, system-wise, between the drivers and the enclosure, is tough to say. However, the result was quite favorable.)

Steve F.

[Robert_S]

I am still trying to ascertain the proper AR part numbers for this tweeter, and the woofers in the 6 and the 7. The model 6 seems to be the first of these three into production (1971?), and also the main focus of my search

Here are a few topics that may be of related interest:

AR-6 crossover:

http://www.classicsp...?showtopic=1687

AR speakers in the Royal Opera House in Copenhagen:

http://www.classicsp...?showtopic=1880

AR-7 Crossover Diagram:

http://www.classicsp...?showtopic=4834

AR-7's with walnut cabinet thrift find:

http://www.classicsp...?showtopic=5682

I am quite certain that much of my query can be answered within CSP discussion or library, but I admit to having some difficulty using the search function and archive material on this terrific site.

Regarding the search feature limitation, a post quoted from Mark, the site administrator:

Here's an option for many of you that would like to search for words or phrases containing words with less than 4 characters - e.g. "KLH" or "KLH 22", now that Google has indexed a great deal of the new Library and this forum:

Prefacing a Google search with "site:classicspeakerpages.net" (no quotes) will cause Google to search only classicspeakerpages.net for that particular search. So:

site:classicspeakerpages.net "KLH 22"

Would kick back Google results for the exact phrase "KLH 22" anywhere on classicspeakerpages.net.

Mark

For example, a couple of linked searches using the above technique:

site:classicspeakerpages.net "AR-6"

http://www.google.co....net+%22AR-6%22

site:classicspeakerpages.net "AR6"

http://www.google.co...s.net+%22AR6%22

Robert_S

[michiganpat]

as a tangent to steve's great commentary, I'll add that I love, love, love the AR18's my uncle gave me. these certainly are the mightymouse of vintage speakers. powered by my marantz 2265 (also a gift from my uncle, who bought them new in '78), they have very pleasing, almost authoritative bass...the tweet is amongst my favorites. the crossover of the 18 is the same as the 7...looks like the only real difference is the ADD series styling vs. the "classic era" styling

[ra.ra]

Apologies for delayed response here - I've been away briefly. Many thanks to all for the excellent and helpful comments.

Steve F once again provides a succinct yet detailed history of AR's product line development. Most interestingly, he suggests that the change in x-o freq. was most likely due to a change in woofer, but curiously, AR was still citing their 'unusual' woofer in literature after the x-o was listed at 1800 Hz. I had been thinking that the change in x-o from 1500 to 1800 Hz instead coincided with the product change from the rheo pot (w/three terminal) to the three-position HF switch (w/two terminal) versions. See the partial blips from literature attached (including AR-7, which I previously uploaded incorrectly), which have been the basis for providing me with a smidgen of information.

This 8" woofer identification has me somewhat perplexed, and maybe someone can help me interpret this information in the attached AR parts list. Steve is also correct about the poor marketing decision to stay with three 8" two-ways (4xa, 6 and 7) thru these years, but I expect that the model 4 was so closely identified with their corporate success that it was too difficult to jettison.

Thank you, Robert_S, for the several excellent discussion links on the AR-6 and AR-7. I will look closely at all of them to see if I can identify part numbers or a more thorough understanding of the various permutations of the AR-6. Also, the search tips via the administrator yield far more fruitful results than I was able to previously uncover, so again thanks.

Full disclosure: aside from my general interest in the 'classic' AR products, a friend of mine is about to ship me a pair of AR-6's which he picked up for a reasonably small sum, and although I do not yet know all the details about this pair of speakers, I've been led to believe that they have strong potential to eventually become a fine addition to my modest collection. I'm not sure yet what they might need in terms of restoration, but I am simply trying to build my knowledge base so that I might be able to make some intelligent observations and then take steps to improve any deficient aspects of this pair. I'll report more when I have more detail.