Stimpy

If me, I'd dread fighting out that masonite board. It's stapled and glued down. Not easy to pull, especially intact. I'd rather leave the board in place, and unsolder the PC board. A decent iron and a good solder sucker should be enough to get the job done.

With my 90's, I started with zip code. Next, Monster Cable. Finally, Kimber Kable. Each upgrade was noticeable, but I wasn't prepared for the differences the Kimber Kable 8TC made. More open, with a wider soundstage and more palpable midrange. But, the improvement in bass surprised me. Deeper, tighter, and more dynamic. It sounded like I'd added a sub, than just swapping speaker wire.

I love my AR58S speakers. Another 12" AR 3-way. Nothing wrong with them sonically. Not bass heavy, or thick in the midbass. Just capable of responding with surprising bass quality and quantity, as the music requires it. Open and airy in the mids and treble too. A fine speaker, which I'm sure could describe the 303's. After all, they are a Ken Kantor design. No junk there.

Stereophile AR303 review.

I'm lucky. The foam inserts on my 90s still look pristine. Not sure why, just glad it is what it is.

If one wants to recap these speakers, it's not difficult or expensive, and at their age, an owner should. With the AR91's, only the 4.0uF and 24.0uF capacitors are series capacitors, in line with the tweeter and UMR dome. Those 2 caps will have the greatest impact on sound. Personally, I always use poly/film capacitors for them. NPE electrolytic are also fine, if the restoration budget is a concern. Up to the owner. But, for the series caps, it's not too expensive to try a decent poly. NPE for the rest. Parts Express, Parts Connexion, Madisound, and Sonic Craft are all good sources for capacitors. Dayton 1% and 5%, Audyn Q4, Jantzen Cross-Caps, ClarityCap PX, SA, or CSA, Mundorf MKP or EVO, and SoniCap are all fairly affordable poly caps, that sound good.

I used those same binding posts on my AR90's. The correct length and the same thread pitch. A perfect fit.

I use AR58S speakers, which use essentially the exact same drivers, as the 91's, in a large bookshelf design. Beautiful sounding speakers, which lead me to believe your 91's deserve some love. And Bill LeGall, at Millersound, is a great place to start. Bill is a speaker genius, who will treat you right. Oh, I have AR-1MS, AR92 and AR90 speakers too. So, a bit of AR bias involved in my comments. Good luck, and glad to hear you're saving those speakers!

Some good info concerning UMR issues and ferrofluid issues in these threads. Most appear to feel the ferrofluid should be OK. But, as RoyC pointed out in one thread, there's also the issue of the fiberglass damping under the dome, becoming displaced and causing output problems. Maybe that's at play here? Are my AR9s getting old? AR-3 Restore or not? Replacing ferrofluid on dome upper mids of AR-90s Dried out ferrofluid ? Teledyne Era AR's 200028 vs 200032 1 1/2 inch MR

I've always wondered if the 303/302 dome was different from the 338, or was it the same dome, where one used the additional mesh and damping material, and the other model didn't? More of a cost saving measure? And if you like the 338, how about the 302T?

The 338.

I'm not sure if it was here at CSP or AK, but there have been threads discussing aging ferrofluid. I remember reading responses to the effect to where AR was purported to use a high quality ferrofluid, that wasn't subject to drying out or crystallization? And even if the ferrofluid did thicken slightly, normal playback levels (and the resultant heat) would be enough to thin the fluid to normal. I have no idea as to the validity of these claims, but reading the statements were enough to ease my mind on the subject.

I truely believe that midrange dome, is the same driver used by Ken Kantor, in his final AR series of speakers. Those were the AR303s, 302s, 338s, and 302Ts ( and maybe others). Ken's designs used the mesh cover and damping material over the dome, but I'm pretty sure that's the same dome underneath. As such, hopefully owners of one of those speakers will chime in?

AmericanRadioHistory.com has scans of Audio Magazine online. The January 1985 issue is available. Issues of High Fidelity and Stereo Review are also downloadable. There are literally dozens of different publications listed on the ARH homepage, that can be read again. A treasure trove.

I hope the documentary comes to fruition. That would be very interesting to see. Also, in a similar vein, the Vilchur home was recently sold? I'd love to hear the stories that it could tell. Vilchur Home

Vintage AR, via ebay, sells a pre-cut foam kit. https://www.ebay.com/itm/ACOUSTIC-RESEARCH-AR-9LS-AR-9LSI-BASS-CHAMBER-FOAM-KIT/162368817302?hash=item25cdef8896:g:b1YAAMXQjq5Q9QnG DIY types often buy Sonic Barrier foam from Parts Express, and cut their own kit. https://www.parts-express.com/sonic-barrier-1-acoustic-sound-damping-foam-with-psa-18-x-24--260-525 There's 3 different thicknesses to choose from. Use what's appropriate.

Yes, they are 4 Ohm tweeters. They look like this, with the face plate removed.

Tweeter plates, from this series, are almost always on eBay.

I'm on my tablet, and I can't 100% verify this comment, as my tablet can't open the .Tif files. But, double check the Library, in the AR Drawings section, for exact part tweeter numbers, as that looks like the standard 0.75" tweeter diaphragm. It's used across many AR speakers, including AR9s, AR90s, AR91s, AR92s, AR38Bs, AR48Bs, AR58Bs, and AR1MS speakers. The mid-tweeter plate, as used on the 38s, 48s, and 58s can be found fairly cheap, and those tweeters could be used for donor diaphragms, on your 9LS speakers.

I didn't know the dual dome plates could be disassembled, in order to refresh the ferrofluid? Is it a difficult process? I've wondered about doing that on my AR90's? But, I'd probably be too apprehensive to try. Regardless, please post some pictures of the finished speakers. Plus, well done!

It looks like an AR28B, 200050-0 woofer, will work too. It's impedance matches the 200027 woofer.

I always wondered about those white dust caps, and why they were used? Strange, compared to the typical AR style? I have to ask, I wonder if they were heavy enough to alter resonance frequency, to extend the lower bass limit? I guess it would have been an easy way to tune the speakers, if so? Also, if still available, I'd be interested, if no one else shows a desire for them? They are what I'm considering for a center speaker project, that I mentioned. PM a price, if you don't mind? Thanks!

I looked into LMR substitutes, while I was researching building a center speaker, to match my AR90's. According to my notes, the Tonegan 1210045-0 woofer should work. Also, the 200037-0 woofers, from AR18S speakers, match the LMR impedance, so they should work too. Plus, 1st gen AR94's used the same 200027 woofers. But, that was the bottom driver in the 94. Not the middle woofer. I never could figure out that decision? Oh yea: LMR 8" Fs 38 hz Re 5.75 ohms Qts .47 Qes .7 Qms 1.3 Le .42 mH

Awesome! Congratulations! I am a former Teledyne employee as well. Though, it was Teledyne Avionics. Still, the 50% off Employee Discount was offered to the Avionics personal too. That's how I picked up my AR90's, around 1981. But, the 9's, weren't offered at the time. I still wish they had been available. I probably would have bought those also.