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Got me some nice new AR7s - and they're lovely!


RobHolt

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Rob,

Beautiful speakers! I love the euro cabinets and careful matching of the veneer. If you had not told us they were teak veneer I might have thought they were vinyl, the way the grain wraps around from top to sides. Great job!

ra.ra,

The xo in my 7s looked exactly like your 2nd example. They were SN 008517 & 008518 and had real wood veneer but obviously not real walnut. Apparently stained birch (thanks for the clarification Tom). This was another case of "too many speakers, not enough room" so I sold them after a recap and new linen.

-Kent

post-101828-0-42053200-1395773877_thumb.

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RobHolt, can it be assumed that your speakers have the normal (and only?) AR-7 crossover, with a single 6uF cap and a 3 ohm resistor (plus the two position switch), as shown in attached pics?

Final point about the teak veneer - - - I happened to see this page of veneer options from an Ohm speaker website and, to my eye at least, these two samples (oak, teak) illustrate very well the observations I was trying to make about the various grain structure found in teak.

And lastly, Tom's remarks (and Aadams' follow-up) about the AR-6 will prompt me to begin a new thread in the next few days (after I get a few good pics together) - - - I have recently come into possession of a fairly early pair of AR-6's which may be an excellent case study for this topic, and I'd rather keep this thread focused on the OP's AR-7's.

attachicon.gifAR-7 crossover(s).jpg attachicon.gifveneers.jpg

Single 6uf cap and 3 Ohm resistor, just like the pic on the left.

Mine were measuring 11uf though.....that's age for you!

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Tysontom

You have provided valuable info for anyone looking to purchase an AR6 for its unique bas performance and have raised the following question.

Both the 1975 and 1970 classic brochures describe the AR6 as having a woofer that achieves performance close to "theoretical" limits, intimating extraordinary bass performance for a cabinet its size. Do you know if the "special" woofer was still being used in 1975 or had production switched to a universal 8" by then? Asked another way, was the phenomenal bass performance limited to the first 1000 units around 1970, after which an AR6 was pretty much like any other AR 8" two way speaker?

Adams

By 1975, I think AR was using the universal woofer on the AR-6 (this one has the ceramic-magnet woofer). i don't actually know the exact date or serial number range that AR switched over to that new-style woofer. It was the earlier, open-yoke woofer (ribbed cone) that had the long voice coil, and this type woofer was discontinued sometime after AR moved from Cambridge to Norwood in 1973.

All of the AR-6s nevertheless had excellent bass performance, but the earlier woofer had the greatest excursion capability. For example, the AR-6 has a lower system resonance than the AR-4x or the AR-7, and thus it can go lower before it begins to roll-off naturally, at 12 dB/octave, below the resonance frequency. The distinction of the old-style woofer was the ability to make larger excursions with lower distortion, but this was a subtle difference that would be most noticeable on organ music or perhaps some low-frequency electronic music.

—Tom Tyson

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All of the AR-6s nevertheless had excellent bass performance, but the earlier woofer had the greatest excursion capability. For example, the AR-6 has a lower system resonance than the AR-4x or the AR-7, and thus it can go lower before it begins to roll-off naturally, at 12 dB/octave, below the resonance frequency. The distinction of the old-style woofer was the ability to make larger excursions with lower distortion, but this was a subtle difference that would be most noticeable on organ music or perhaps some low-frequency electronic music.

—Tom Tyson

Yes, I've found around 33Hz Fs for the original AR4x ribbed woofer and also reformed universal woofers from the 18, with both going a system resonance at around 65Hz in the AR4 cabinet.

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  • 3 weeks later...

Great job, Rob! I love these speakers, and in the last couple of years I've refurbished two pairs and given them to my kids to use in their university lodgings. In both cases they tell me that they get rave reviews from their housemates, which is praise indeed. One pair belonged to my father, so it's nice to know another generation can benefit from them.

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