RoyC

I think an old NAD receiver is a bad idea. Until its very recent closing, I was repairing speakers for a local shop for many years, and old NAD products were not popular among those tasked with repairing them. The shop was in business for over 45 years, and apparently NAD products were among the most frequent visitors. They were also troublesome to diagnose and repair. In fact one of the old-timer tech's referred to NAD as Nasty Audio Devices. 3a's are not speakers you should play chicken with. In the past 3 months I've repaired KLH 17's and AR-3a's with fried voice coils due to faulty "vintage" amps (they weren't NAD) passing DC to them. It should also be noted that in both cases they were being operated at low to moderate volume levels. I agree with Kent. A pro amp brand like Crown connected to a nice preamp (vintage or otherwise) would be a safer bet, especially for low impedance loads. Along with being new, these amps have excellent protection circuitry. For some reason I thought NAD equipment was always designed in the UK and manufactured in Asia. Roy

Sure...send me a PM to discuss the details.

All good! Best of luck with your project. Roy

The "seal" is not the cause of the distortion. The most likely cause is deterioration of the adhesive holding the surround and/or spider mounting rings to the woofer frame. Another possible cause is deterioration of the adhesive holding the cone and spider together. These are increasingly common issues unique to the AR 10 and 12 inch cloth surround woofers. I've been doing lots of these repairs of late. Roy

The pots are in nice shape, but will require a bit more than delicate polishing. There is both tarnish and some corrosion present, which should be completely removed. Do not, however, use an abrasive on the resistor coil. The capacitor could be an Industrial Condenser brand cap, which should be replaced. Just because it is a large "can" type of cap doesn't mean it is the superior Sprague brand. If in doubt, replacing a single cap is relatively easy to do and will provide peace of mind. If you decide to replace the caps send me a PM. I just acquired a rather large number of them from a (recently closed) shop for which I used to do repair work. Roy

The white foam gasket, and everything in the cabinet, are original. Someone most likely used putty when the replacement woofer was installed in the other cabinet. The serial numbers of both cabinets are rather late in the 4x game, and foam gaskets would have been used in both cabinets by that time. It is not uncommon for those gaskets to tear, requiring replacement when removed. Putty was originally used in earlier days, and frequently used by people replacing drivers in later days. Roy

The "pressboard" frame is an original AR frame. The woofer with the foam surround appears to be a later (early 80's) AR woofer. It is not original to the 4x. Roy

Hey Glenn, Just sent you a PM. Roy

Looks good from here... Roy

..and what would those two things be?

New leads are part of the deal. If you would like more details, send me a PM.

Good point, Gene. Coincidentally, I just refurbished some of these for Vintage_AR. Something I found interesting is they all measured just under 14 ohms. I recall that being the case with others of this generation I measured a few years ago. Roy

Generally speaking it is usually better to stick with the original configuration. Some dust caps are porous to provide additional cooling, and others may allow a small amount of cabinet leakage as a type of "aperiodic loading" through the spider and dustcap (ie AR-4x). As for the Advent woofer it is hard to say, as I've seen later versions of the woofer with non-porous felt or paper dustcaps. In any case, I wouldn't go to the trouble of applying anything to your cloth dustcaps. Roy

I'll check for woofers when I return to the shop next week, Pete. I was referring to a schematic for the large tweeter magnet version, but after reading the old thread Doug found (thanks!) I believe I have enough information to proceed. Roy

Without a doubt, the mids would benefit from refurbishment. Since the AR-3 mid substantially affects high frequencies as well, and is often in need of significantly more work, I recommend dealing with both of those first. You should also make sure you can hear a difference as you turn the level controls. It is very common for the tweeters and mids to produce little to no sound at all until the controls are properly serviced or replaced. (In my experience, cleaning solutions such as Deoxit are seldom effective to adequately restore proper functionality to typically crusty AR pots.) You have very early specimens. Your version of the AR woofer is actually more typical of the AR-1, though I'm not sure if that is the cause of your concern regarding bass performance. Roy PS Send me a personal message if you would like me to be of assistance. I see you are in Boston. I'm in upstate NY not too far from you.

I usually use Goop, Gorilla Clear Grip, or E6000 for crossover components these days. They are all essentially the same.

I wouldn't be concerned about the resistors. In fact, I often run leads from the L-pads and glue them to the cabinet brace just to make installation easier. Two of us are repairing the 3/4" black dome tweeter used in the 3a and other AR models. Chris1this1 is the other forum member. He does a great job of winding a new voice coil to original spec. I have had limited success repairing the AR-3a type of mid, and I'm not aware of anyone rebuilding this one. Roy

All good here, Pete. I try to visit this forum on a regular basis. I haven't seen you here much, but have recently consulted a number of your insightful posts in other audio forums. Regarding Doug's comments on tweeter changes, I will be acquiring a couple of first generation Small Advents as a result of the imminent demise of a brick and mortar shop for which I've been repairing speakers. They have been knocking around the back of the shop for a long time, having convinced the shop owner not to pass them on to the "recycling" guy. The original green tweeters are missing. Some years ago I noticed an obvious difference in sensitivity between a smaller magnet green tweeter and a larger magnet orange dome version on the bench. Additionally, based on the last orange cone tweeter on the parts shelf, the cabinet holes of my early specimens will need to be enlarged to accommodate later versions of the tweeter. I'm also aware the Small Advent crossover was changed along the way, presumably to compensate for tweeter differences. Do you guys have any other SA experience or schematics to share? I've worked on a number of these over the years, but too long ago to remember specifics. Roy

Hi Kent, I actually have been restoring many AR-3 mids these days. Even when they are functional they often have compromised output due to dome suspension issues. I see you are back in the pot business! Roy

Hey Pete...I've found some crumbling Rockwood resistors in KLH speakers as well. Roy

No, The AR-3 tweeter and mid have much lower dcr. The tweeter is just under 2 ohms, and the mid is closer to 2.5 ohms. Roy

For the record, I lobbied not to include this minutiae in the 3a restoration guide. In practice, there is no reason to use the resistors. The level controls and ancient drivers are much more influential than the additional fixed resistor. If you really want them to behave "authentically", use electrolytic capacitors. For the simple AR-3 crossover I would just use the Daytons you have chosen Regarding the tweeters, they seldom suffer the same type of degradation as the mids. If the output seems OK, and the dome is not protruding from the voice coil gap ("popped dome" issue), I wouldn't be too concerned. Sometimes the foam suspension "blobs" and/or the clear rubbery material around the tweeter dome needs to be refreshed. The tweeters can always be dealt with after everything else is completed. Roy

Agreed...imo, it was just another example of misleading audio forum speculation.

Ron, The Midwest tweeter is nearly an exact replica of the AR-11 tweeter. It is the best of all replacement options for the 11 and 10pi. Roy

Not that I'm aware of. JKent's replacements are better.