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Unusual AR-4X's


dynaco_dan

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Hi there;

Recently a pair of AR-4X's, serial numbers FX33470 & FX33500, were listed and sold for $212.50 on eBay.

The woofer is unusual in appearance, I've seen these before though, but the tweeter appears to be more unusual than the usual tweeter used, in the AR-4X's at least.

The tweeters appear, even with this late a serial number, to have the AR-4 tweeter/AR-2AX mid range drivers but with the center portion open, rather than completely covered over with fiberglas.

Here is a few photos from that auction.

post-101040-1199277335.jpg

post-101040-1199277347.jpg

post-101040-1199277355.jpg

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Guest speedracer
Hi there;

Recently a pair of AR-4X's, serial numbers FX33470 & FX33500, were listed and sold for $212.50 on eBay.

The woofer is unusual in appearance, I've seen these before though, but the tweeter appears to be more unusual than the usual tweeter used, in the AR-4X's at least.

The tweeters appear, even with this late a serial number, to have the AR-4 tweeter/AR-2AX mid range drivers but with the center portion open, rather than completely covered over with fiberglas.

Here is a few photos from that auction.

I have a pair of 4's, # F-07831/08752 with woofers like that

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Hi there;

Recently a pair of AR-4X's, serial numbers FX33470 & FX33500, were listed and sold for $212.50 on eBay.

The woofer is unusual in appearance, I've seen these before though, but the tweeter appears to be more unusual than the usual tweeter used, in the AR-4X's at least.

The tweeters appear, even with this late a serial number, to have the AR-4 tweeter/AR-2AX mid range drivers but with the center portion open, rather than completely covered over with fiberglas.

Vern,

I believe those are actually AR-4s rather than 4xs. The AR-4 was only made for about a year -- 1964 -- before the updated AR-4x was introduced. The tweeter shown is the 3-1/2-inch version that was also used in the AR-2ax as a midrange. At some point, probably just before the introduction of the improved AR-4x, the fiberglass covering the top portion of that driver was opened-up to increase on-axis output from that driver (I'm not positive about this, but I think this is what AR did to improve on-axis response). The fully covered 3-1/2-inch tweeter was very smooth and had good off-axis response, but it trailed off in the higher frequencies. The 4x 2-1/2-inch tweeter was much smoother and flatter, both on- and off-axis.

I'm not too surprised that the AR-4 sold for as much as it did: these are somewhat rarer than the 4x and this pair appears to be in good condition. However, a new-appearing pair of AR-4xs, with original boxes, sold for over $1000 a couple years ago, so you never know what these things will bring on the auction market.

The criss-cross on the woofer cone was done for improved damping (not stiffness). It was a soft compound that was poured on the cone with the effect of absorbing energy traveling across the cone at higher frequencies. This was similar to the damping rings used in some other woofers. AR (and KLH followed with some of their speakers) used this criss-cross method on several woofers, including the AR-2a woofer.

--Tom Tyson

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Attached is the file photo used by AR for the AR-4. From this picture it can be seen that the fiberglass around the tweeter is open, but in this case the fiberglass appears to be darkened.

--Tom Tyson

Thank you Tom for your insight;

That single photo is familiar to me.

It appears to show a good, really good coating of the woofer surround and maybe they also used it to darken the tweeters fiberglas at the same time.

I only started this topic was because of the unique appearance of the missing fiberglass and that the serial numbers, which I thought were AR-4X's.

Another slight iteration of a speaker once sold by AR, however slight.

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Guest matty g
Attached is the file photo used by AR for the AR-4. From this picture it can be seen that the fiberglass around the tweeter is open, but in this case the fiberglass appears to be darkened.

--Tom Tyson

Hi -

Does anyone know if the crossover cap in this system is the 20 mfd used in the 4x? Also, is the midrange in the second generation 2ax the same as the one used in the first generation models, and if so - what about using the 2ax midrange as a tweeter in a 4x system? Any comments/criticism welcome!

Matt

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Hi -

Does anyone know if the crossover cap in this system is the 20 mfd used in the 4x? Also, is the midrange in the second generation 2ax the same as the one used in the first generation models, and if so - what about using the 2ax midrange as a tweeter in a 4x system? Any comments/criticism welcome!

The AR-4 used a 6 mfd capacitor but the same 1.24 mH choke. The 3-1/2-inch midrange used in the AR-2ax from 1964 onward was the same as the tweeter used in the AR-4. The variation in the fiberglass over the top of the 3-1/2-inch occurred early, but the standard (and most common) version had fiberglass covering the entire area of the cone under the metal grill. There is no difference in the 3-1/2-inch AR-2ax midrange and the AR-4 tweeter, and they are interchangeable.

--Tom Tyson

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