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AR5 rebuild


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I am restoring very late AR5 pair. 2 issues have puzzled me. First the woofers do have different part numbers. The first one do have 200004-2 label and 7543 date code. The second one do have 200004-3 label and 7505 date code. Only external difference seems to be 20004-2 backside is painted black and other one is natural colored. Both crossovers do have similar Sprague Compulytic 72UuF cap for woofer,but one does have 24uF Compulytic for mid and other one does have smaller 24uF axial cap for mid.

As Compulytics do have good reputation and they measure close to spec... one 72uF and other 80uF... it would be nice to save them, but one cap terminal is loose and this will give erratic figures when measured from wiring. As solder does not adhere to stud, is it safe to use center punch and hammer to close the gap between stud and tag? Or are the caps beyond repair and ready for replacement?

Are the 200004-2 and 20004-3 woofers similar or should I try to get similar part numbers for these.

Best Regards

Kimmo

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Each of these documents seems to suggest that your 10" woofers were originally intended for different speaker models, but whatever their minor differences might be, for restoration efforts they are generally considered to be virtually interchangeable and will perform similarly. This assumes they each have the square magnet and similar baskets, cones and original suspension - - also assuming here that you will need new foam surrounds. (Suggestion: the addition of photos in these queries almost always leads to more satisfactory responses.)

Good to know that you are measuring the caps to determine their status, and as you've already determined, these Compulytic "cans" often do seem to retain close to their original spec values. As for replacement?....... it's just a personal decision weighing several factors ...... how important is it for the two crossovers to "match"? ....... how much work is required to repair broken terminal? ...... how close to original cap values do you want to be?

Curious if yours have the slim profile Euro cabinets? Original potentiometer controls? AR-5's are terrific speakers, keep us posted.

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Cabs are slim profile Euro ones with walnut finish. Grille cloth is unusual brownish one. They seems to be fairly original exept refoamed woofers. Pots are not scratchy and all drive units seems to work, even sound quality is somewhat dull. Most likely this will be cured when series caps have been replaced and pots cleaned.

Cabs were in fairly good condition. Some dents have been repaired earlier and walnut finish was quite dull before light sanding and several coats of BLO. Top surfaces are still somewhat dull looking. I was most likely unable to remove all dirt from veneer before BLO. Last year when I refinished 2ax cabs, I sanded almost trough top veneer of one cab and tried now to avoid this.

Badges have been cleaned. It is most unlikely to find original brownish cloth that came with cabs. The original cloth is a bit shabby looking, as there is one tar spot, one hole on and 40 years worth of dirt on them...but I found more original looking light linen grille cloth than one I bought last year from Vintage AR for 2ax´s. I will use this for my AR 5`s.

I will post more info and pics later.

Best Regards

Kimmo

post-126436-0-68840400-1405615271_thumb.

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It all looks good from here, and I suspect that all of your remaining issues are repairable. The cabinets just might need a little more elbow grease on your part, and it is a good idea not to be overly aggressive with the veneer sanding. They will look much better with the light grille cloth, too.

Those woofers with new foam look great, as do the other drivers - - - nice to see they are all rear-wired. Not sure what else to say, but if all the drivers are indeed functional, then hopefully restoring pots and replacing caps will do the trick to brighten up the performance.

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  • 1 month later...

I have now got new caps for my AR5´s, but I have not done recap yet as I have not decided what I will do for to the pot´s. Pot`s worked when I tried them. When I cleaned 2ax pot´s, it was quite clear that cleaning is not long term solution.

Roy has posted earlier that he prefers 8 ohm L-Pads to original pots. Sometimes wired as L-Pads and sometimes with 25 ohm resistor. Roy´s opinion about which option works better with AR5 (and why?) would be appreciated.

Best Regards

Kimmo

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I have now got new caps for my AR5´s, but I have not done recap yet as I have not decided what I will do for to the pot´s. Pot`s worked when I tried them. When I cleaned 2ax pot´s, it was quite clear that cleaning is not long term solution.

Roy has posted earlier that he prefers 8 ohm L-Pads to original pots. Sometimes wired as L-Pads and sometimes with 25 ohm resistor. Roy´s opinion about which option works better with AR5 (and why?) would be appreciated.

Best Regards

Kimmo

Hi Kimmo,

I prefer to use an 8 ohm L-pad with no enhancements for the tweeter, and the L-pad with a parallel 25 ohm resistor across the driver for the midrange.

The old tweeters were reticent to begin with, and 40 years +/- have done nothing to improve this characteristic. The L-pad (without the resistor) will coax a bit more output from them. The condition of this type of tweeter, which was used in a number of AR models (4 and 8 ohm versions) is quite variable these days.

15 watt 8 ohm L-pads are reliable and can be purchased from vendors such as Parts Express, Madisound, and Erse, among others here in the US. The same items are sold as "AR" controls or pots on Ebay at a much higher price (with the "8 ohm" stamp removed).

Roy

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