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AR-8 crossover schematic diagram ?


owlsplace

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Here is one crossover pic, which suggests the woofer running full range, the single 10uF (or paralleled 5uF) caps for the tweeter, and the two 3 ohm resistors on the 3-position switch. Below is the thread where our man Roy has confirmed this.

Also, the square badge is original (but with light grille cloth) and the AR-8 came in vinyl cabinet only. I have one parts list from 1975 which shows the AR-8 woofer listed separately from the AR-2ax (late), AR-5, and AR-LST-2 10" woofers, so perhaps it was tweaked a bit to accommodate the anticipated high volume levels of rock music enthusiasts, to which this speaker model was marketed.

http://www.audiokarma.org/forums/showthread.php?t=490038

post-112624-0-83130700-1440799250_thumb. post-112624-0-18786600-1440799478_thumb. post-112624-0-52162400-1440799656_thumb.

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More info on the simple crossover.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6921

Oops, apparently some AR-8's did have real wood veneer cabinets. Based on comments herein, I'd guess very early American AR-8's did have real veneer and even the pot control for the tweeter.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=8033

And, I assume you're asking about the larger USA AR-8 and not this cute little Euro AR-8s.

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That's the one ... rare birds I guess. I became curious when I saw one parted out on the auction site. There is another set for local pick-up only but too long a drive for me.

So why no 2-way with 10" woofer by AR? Would like to hear these some day. Maybe I'll have to make my own set :)

Roger

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That's the one ... rare birds I guess. I became curious when I saw one parted out on the auction site. There is another set for local pick-up only but too long a drive for me.

So why no 2-way with 10" woofer by AR? Would like to hear these some day. Maybe I'll have to make my own set :)

Roger

AR 2x and AR 14 would be two other examples.

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AR 2x and AR 14 would be two other examples.

Ah, yes, looking at the timeline for the Classic period it looks like the 8 superseded the 2x which was replaced by the 14 in the ADD period with its modern cabinet styling.

So the AR-8 wasn't really an anomaly but it was in the same price range as the 2ax which I'm sure limited its appeal to most buyers not to mention the less expensive AR-7 with its look-alike tweeter; however, TomT suggested the 8's tweeter was doped with silicone so it should have a different part number.

Roger

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Regarding AR's 10" two-ways, let's not forget that the 2x had two versions (each with distinct woofer and tweeter), and both of these were preceded by the original AR-2 with its dual tweeters (at right in first pic attached).

I think Tom's comment about the silicone in the AR-8 tweeter referred to grease (precursor to ferro fluid) used in the VC gap, and not a "dope" application, which I tend to think of as a topical coating for cones, dust caps or surrounds. It is quite possible that the AR-8 tweeter was unique in this way, but I have always thought of it as being the same part number that was concurrently used in the AR-4xa, AR-6 and AR-7 from the same period (second pic).

Also interesting is Tom's remark that the earliest AR-8 woofer was unique regarding its greater sensitivity, which seems to be confirmed by the catalog page in post 2 which suggests a minimum power requirement of only 15 watts for the AR-8, as opposed to 20 watts for the smaller AR-6.

post-112624-0-92853300-1440868636_thumb. post-112624-0-06552800-1440870719_thumb.

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The AR-8’s 10-inch woofer originally was described as a slightly more efficient version with higher power handling than the 2ax/5 woofers. The system resonance for the 8 was spec’d as 52 Hz, lower than the 56 Hz of the 2ax/5. There is no question that AR initially represented this woofer as being different than the 2ax/5 woofer. The AR-8 was marketed and advertised as the “first accurate speaker for rock music” with the ‘increase’ tweeter position giving ‘slightly harder, more exaggerated’ high frequencies or some such nonsense. I’d have to go back and check the original ads—I’m going from memory here.

This was such a disaster of a speaker, the only outright failure of the original Classic series. It sounded fair, at best. It was butt-ugly in vinyl. At $119, it was $17 more than the vinyl Large Advent, and it couldn’t match its bass or midrange ‘punch.’ I don’t know what the marketing geniuses at AR could have been thinking.

Here is the AR 10-inch 2-way progression, 1954-1976:

1957-- AR-2 10” cloth surround woofer, dual 5” angled mid/ “tweeters” (maybe 13k with a stiff tailwind), 2k x-o.

1964-ish-- AR-2x 10” cloth surround woofer, 3 1/2” cone mid (same driver as AR-4 tweeter, 2ax midrange), 2k x-o.

1970-- “New” AR-2x foam-surround 10” woofer 2 ½” cone tweeter (same driver as 4x and 1x tweeter), 1.2k x-o.

1973-4-- AR-8 Unique 10” foam surround woofer (different than 2ax/5), 1 ¼” tweeter (same as 4xa, 7, 6), 1.8k x-o.

1976-- AR-14 ADD 10” foam surround woofer, 1” dome tweeter (initially a Peerless dome, then an AR-built dome), 1.3k x-o.

In the years following, AR service providers have simply suggested a “universal” 10-inch woofer for any AR 10” model.

Steve F.

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I 've never seen or heard one of these AR-8 in Europe , but I believe it was the first AR answer to the market , slightly different from the '50s and '60s, and at the same time their loss of identity. AR speakers of the Classic era are real hi-fi instruments, designed for sophisticated audiophiles and musicians, while the largest diffusion of hi-fi in the '70 needs speakers more " impressive " , also for youngest rock listeners. But I think it' s a mistake, You can' t say " the Rolls-Royce is too slow " or " a Ferrari is too discomfortable or too noisy " , a Rolls must be silent and a Ferrari must be fast . In the same way, an AR speakers doesn' t have to imitate JBL speakers like 4311 or Decades, designed particularly for pop/rock music and to a particular listener.


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Looks like the TSW-310b was the last of the 10" 2-ways. They managed to get the sensitivity up to 90db according to the history spec sheet: http://www.aphenos.net/electronics/speakers/klh/all_ar.htm

We'll see if the AR-8 drivers actually were different soon as I took the parted out drivers off the auction site. I suspect they will drop into my other speakers without any complaints or maybe I'll get creative ;)

Roger

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  • 2 weeks later...

...

We'll see if the AR-8 drivers actually were different soon as I took the parted out drivers off the auction site. I suspect they will drop into my other speakers without any complaints or maybe I'll get creative ;)

Roger

The AR-8 drivers came in today. The woofers have 200004-1 part numbers and early '75 date codes. TomT describes them here: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=8033&p=98856

"By 1974, AR began using the "universal" woofer in the AR-8." This doesn't jive with the date code on these woofers.

Robert tracked down a drawing for this woofer in the archive: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=7207&p=92994

The tweeters look like standard 1-1/4" rear wired drivers used in other models with early 1975 (561 7504) date codes. Robert's referenced drawing shows the 200005 tweeter was used in the AR-8 and according to the library literature number 200005-0 was used on the AR-6, 7, 8 and 4xa models.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6066&p=85737

Not sure why TomT thinks the AR-8 tweeter had silicone on the vc.

I'll try the woofers in one of my AR-5 sets that are slated to get HiVi tweeter replacements and use the AR-8 tweeters to replace rear wired 4xa and 6 model tweeters that I had previously bridged breaks on the vc leads. I only have two cabs that use the rear-wired version of this tweeter.

Another organ transplant from the AR diaspora where classics refuse to die ...

Roger

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  • 9 months later...

Saw a nice set of AR-8's sell on the auction site recently for $80. The seller had to run them twice and drop the price. I think these qualify for the least popular of the Classic-period speakers -- I think the drivers would have sold for that alone. I have yet to mount the previously mentioned drivers (earlier post0 in the AR-5 cabinets although I have everything necessary to do the job except time ...

Roger

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Aside from the mediocre sound, the ugly appearance and the ill-conceived marketing campaign that made it the most spectacular flop of the entire Classic series (the only true out-and-out failure from 1954-1974), the AR-8 is interesting for a few other reasons.

First, the 10-inch woofer—at least at the beginning of this product’s life—was indeed a different woofer from the one in the 2ax/5. AR’s own lit on the AR-8 said something to the effect of, “....we’ve used a 10-inch woofer that is somewhat more efficient than our other designs.....” and the system’s resonance was spec’d at 52Hz, different and lower than the 2ax/5  system resonance of 56Hz. Both of those data points indicate that the 8 had a different low-frequency design than the 2ax/5.

 

The other design interesting aspect was AR’s contention that the “Increase” position of the tweeter level switch provided “sharper, harder, more exaggerated high frequencies, appropriate for today’s rock music,” or words to that effect. In other words, AR was admitting outright that their other speakers were “dull” on the popular music of the day and with the 8, they were intentionally abandoning any pretense of musical accuracy—quite a departure for them.

The AR-8 failed on every count. Its bass was not any stronger or deeper than the 2ax or 5 in practical, real-life terms, so AR soon saw the folly of manufacturing separate woofers for the different systems and went to a “universal” 10-incher instead.

 

The  8’s “increase” tweeter position did not produce ‘sharper, harder’ high frequencies. The 8 sounded no brighter or different than the AR-6 or 7. (Actually the 7 was the brightest of them all, as I’ve pointed out before, and the High Fidelity Magazine curves show that quite clearly. High Fidelity tested the 6, 7 and 8 and ran curves on them in exactly the same manner, under the same conditions. The 6 and 8 are well nigh identical; the 7 shows an unmistakeable increase around 7-10kHz of about 2dB or so, and that’s exactly how it sounds.)

 

At $119 ea., the AR-8 in an ugly vinyl wrap was $3 more than the Large Advent in real walnut and $17 more than the Advent in vinyl.

If I ever teach a graduate marketing course at Harvard Business School and I want to give an example of a product from a major company that got every single blessed last thing wrong, I’ll tell the class about the AR-8.

 

Steve F.

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9 hours ago, Steve F said:

...  and with the 8, they were intentionally abandoning any pretense of musical accuracy—quite a departure for them.... If I ever teach a graduate marketing course at Harvard Business School and I want to give an example of a product from a major company that got every single blessed last thing wrong, I’ll tell the class about the AR-8.    Steve F.

Didn't they abandon musical accuracy with the 4x? ... which was one of their better sellers.

And then came the AR-9 so if they didn't make this beast than the 9 would have been the 8 -- having a fail in there was a bit of an incentive.

Roger

Edited by owlsplace
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The AR-4 series (which should probably include the 6 as well) has a sound that is very much in line with the larger models. The lows don't go as low, the highs don't go as high and the soundstage is narrower because the tweeters lack the wide dispersion of the domes, but the voicing and "accuracy" don't stick out like sore thumbs.

By comparison, the sound of the AR-8 was like hitting your thumb with a sledge hammer. Roy was probably glad he got out the door before anyone could pin that one on him.

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In their great 1971 full-line brochure (in my opinion as a decades-long marketing/product development/eng dir/mgr, that is about the best brochure I’ve ever seen, in terms of both subjective emotional appeal coupled with objective black-and-white ‘proof’—a perfect balance), AR said of the 4x—“....it may not have as wide a frequency range as some of our other speakers, but in terms of uncolored, natural reproduction, it holds its own with any of them.”

Clearly, AR regarded the 4x as having the same mission of musical accuracy as the 2ax, 3 and 3a. And it clearly succeeded: Julian Hirsch of Stereo Review said its frequency response was unmatched by almost any speaker at any price and added, “We know of no competitively-priced speaker that can compare with it.”

Steve F.

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They do have that 1KHz hump if I remember correctly but I've enjoyed listening to them --- not sure the other 4x "Boat" speaker will get finished this year. Too many other projects.

5 hours ago, Steve F said:

"We know of no competitively-priced speaker that can compare with it.”

Steve F.

Not sure Julian ever said anything bad about an AR speaker ;)

Roger

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Hey I have got a pair of AR38S speakers tucked away in the basement that I re-foamed a couple years ago. If I remember correctly 10 in two ways that diffident sound too bad at all. A little bright. Somewhere I have new  Solen caps for them. Maybe Ill dig them out and give another listen.

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21 minutes ago, larrybody said:

Hey I have got a pair of AR38S speakers tucked away in the basement that I re-foamed a couple years ago. If I remember correctly 10 in two ways that diffident sound too bad at all. A little bright. Somewhere I have new  Solen caps for them. Maybe Ill dig them out and give another listen.

It appears all the "S" series are a little bright. The 38s crossed over at 2KHz while the 4x crossed over at 1.2KHz. I'd be curious how they sound.

Roger

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  • 3 years later...

Hi everybody, the AR8 is a model that sounds very so-soish. It employs components widely tested and used in other models, therefore it cannot be really bad. I own 2, 2ax MkI, 2ax MkII, 3a, 4x, 4ax, 5, 6 (two pairs AlNiCo & Ceramic woofers), 7, 8, 11, 14, 16, 17, 18b, 18s, MST, Rock Partner.

What's wrong with the 8's?

The x-over frequency is the same as the 6's, the tweeter too. In some 6's the woofer response is cut by the .88 Mh inductance. In the 8's is left to run free until it mechanically rolls off.

There you are. 

I placed a 1.0 Mh inductance in series to the negative of the woofer and voilà, I was back in AR realm.
I suspect they stated the 8's are good for rock because they made more noise than the other models.
Rightly so. The 10 inchers, left without restraint in this two way configuration, makes a lot of noise, unpleasant noise.
Now, after the small tweaking, I have a kind of oversized 6's, though the balance woofer/tweeter of the 6's with the 8 inchers is superior...bur not by much.

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