20 replies to this topic

[JKent]

Thought I'd start a separate thread for this project. Background is here:
http://www.classicsp...?showtopic=6546
 

• The speakers are in generally very nice condition but a previous re-foam attempt was done very poorly. I tried to remove the excess glue with alcohol, then lacquer thinner. No luck. John from M_Sound has surround kits but he said the cones are just not available, so I'm hesitant to do this myself.
• AR-Pro clued me into these in the first place, and as he recommended I have sent photos to Bill LeGall at Millersound. I think this is one of those times when paying a pro to do the job makes sense. I've refoamed other speakers (most recently the JBL woofer in the wife's Toyota) but re-doing a botched job may require magic I don't have.
• The foam around the mid and tweet, held in by velcro, has rotted. The previous owner replaced them on one with what looks like A/C filter foam. Apparently AR omitted the foam on later models, so I may just leave them off.
• The crossovers will be rebuilt. RoyC had sent me a link to Erse some time back and I just ordered their Pulse-X caps for this job. Also ordered some resistors, just in case I damage any prying them out of the glue.
• The cabinets have already cleaned up very nicely with just a little sanding with #400 paper on the top of one, and an application of Howard Restor-a-Finish (using steel wool). I may use Watco Oil or maybe just Howard Feed-n-Wax.
• Will keep you posted on the progress. Here are some before shots (will delete them from the other thread).
• All comments welcome. These are not very common, so there isn't that much about them on the various forums. Here's some info I copied from other forums (and there are brochures in our Library):
• Manufacture Years: 1972 - 1978 MSRP: $850.00

Comments by Grateful on AK:
the AR-91 is a 4 ohm system. It is essentially the AR-3a with improved power handling and other refinements in a vertical cabinet. It is perhaps the best 3 way system AR ever made. They require a nice amplifier to sound their best and can absorb the full output of 300 wpc super amp on peaks

Kent

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[Steve F]

As I've reported many times on these pages (my apologies to long-time readers), I owned 91's from 1979-to '86-ish. Nothing but good things to say about them. Probably the best AR-3-way (along with the original 58s). I replaced them when I moved in 1987 with Connoisseur 50t's, which was more of a lateral step than the upgrade I was expecting.

I now have restored-as-vintage 9's, and I am of the opinion that the Vertical Series (92-91-90-9) was AR's high-water mark.

A properly-functioning set of 91's is clearly in the "all-the-speaker-you'll-ever-need" category.

Steve F.

[DON]

As I've reported many times on these pages (my apologies to long-time readers), I owned 91's from 1979-to '86-ish. Nothing but good things to say about them. Probably the best AR-3-way (along with the original 58s). I replaced them when I moved in 1987 with Connoisseur 50t's, which was more of a lateral step than the upgrade I was expecting.

I now have restored-as-vintage 9's, and I am of the opinion that the Vertical Series (92-91-90-9) was AR's high-water mark.

A properly-functioning set of 91's is clearly in the "all-the-speaker-you'll-ever-need" category.

Steve F.

Steve could you post your experience restoring your AR9s on my AR9 post? Thanks Don

[michiganpat]

so, what's the issue with the woofs? VC rubbing, or just ugly from the sloppy application of glue? if it's just the sloppy glue, I'd leave as is, or if isoporpyl alcohol, acetone, or laquer thinner wouldn't touch it, I'd take a fresh single edge razor blade and carefully try scrape it.

the half-a$$ed diffraction foams I'd redo with this stuff:
http://www.foambymai...i-FlowFoam.html ("speaker foam" on the bottom of the page)
or contact http://www.foamspeakergrilles.com/ to see if he can make some, or make some out of F-11, F-13, F-15, or F-26 industrial felt of the proper thickness

http://www.amazon.co...11336322&sr=1-9

[JKent]

Thanks for the leads on the foam and felt. I may try to fabricate replacements or, as I mentioned, leave them off. The speaker grille guy is a good resource for some other projects too.

Regarding the woofers: Yes, ugly. No, they don't rub. But I'm also concerned about whether the previous job used the correct foams, AND there are a couple of spots where the foam roll is glued down, making a flat spot. I'm concerned that the compliance of the surrounds is not right. On first listen, a friend noted the 91s sounded "tinnier" than the 3a's.

So, given the fact that these are supposed to be really good speakers, I think it's worth the modest price to have Millersound do them correctly. The peace of mind factor is a real plus.

Thanks for the input and keep it coming!

Kent

[Robert_S]

All comments welcome. These are not very common, so there isn't that much about them on the various forums. Here's some info I copied from other forums (and there are brochures in our Library):
Manufacture Years: 1972 - 1978 MSRP: $850.00


Kent

Though not on the subject of restoration, the following discussions may be of related interest:

Is The AR-91 A "Sleeper"?

The 'best' AR 12" bookshelf speaker




Robert_S

[JKent]

Thanks for those links Robert.

Packed up the woofers and took them to the FedEx office. They're off to Millersound for refoaming and general check-out.

Awaiting caps from Erse. Should be here Monday: Pulse-X caps in 3.9/250, 8.2/400, 24/250, 39/250, and 100/250. Also a 1/630 to add to the 39. Would have ordered all 250v but some values were out of stock. I have 25uF Clarity caps that "may" replace the 24uF, and will probably add some 0.1 Jantzens that I have on hand to the 3.9. Also may use some 8.0uF "Ultra Caps" I have on hand instead of the 8.2, just to keep the values dead-on. We'll see. OTOH, I bought those as "surplus" so no telling how old they are. Input welcome. Have not tested the old caps for drift yet but I'll bet the black PVC ones are off. Below is a "before" shot of the xo with all values labeled and all the hot-melt glue removed, except on the backs of the binding posts.

I also ordered new resistors "just in case".

Kent

PS: July 25
Erse package arrived today. So here you can see before & after pics of one xo. I used the Erse caps for all except the 24uF. Used the leftover Clarity 25uF caps there (blue cap in pic). I added the 0.1 Jantzen to the Erse 3.9 (hard to see because both are black), and used some nice 1uF Epcos caps I had on hand to bring the 39uF up to 40 (yellow caps in photo. Leads on the Erse 1.0 were too short). Did not need to use the new resistors. Will probably do the other xo on Wed. Then as soon as the woofers come back these will be ready to assemble.

The cabinets are looking good. I used Antique Oil on the tops for some extra protection. Will buff it with steel wool to eliminate any shine.
 

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[michiganpat]

musta spent a small fortune on caps....I woulda used polys like the Pulse-X or Solens on the tweet/midrange circuits (basically everything under ~25uf) but NPE's or the PEx polyesters for the 40 and 100uf...

[JKent]

musta spent a small fortune on caps....I woulda used polys like the Pulse-X or Solens on the tweet/midrange circuits (basically everything under ~25uf) but NPE's or the PEx polyesters for the 40 and 100uf...

Well, the PeX does not come in 100uF. The 40uF Pex is 6.21 vs 10.24 for the Pulse-X. I figured these are TOTL speakers and I wanted to do them right. If they were "lesser" speakers I would have gone for a more economical restoration. I spent about $65 on the Erse caps. The Jantzens, Epcos and Clarity were in my parts box. The speakers cost $75 and I'm having the woofers re-done for under $100 including shipping. So in the end I'll have a pair of AR91s for under $250. A bargain if they live up to what I've been told about them

For many of the speakers I've recapped I like the Carli caps from Madisound. Very cheap and very good. I do plan to try the Erse PeX on a future project. Roy recommended them and I trust his advice in all things crossover.

Kent

[michiganpat]

Well, the PeX does not come in 100uF. The 40uF Pex is 6.21 vs 10.24 for the Pulse-X. I figured these are TOTL speakers and I wanted to do them right. If they were "lesser" speakers I would have gone for a more economical restoration. I spent about $65 on the Erse cpas. The Jantzens, Epcos and Clarity were in my parts box. The speakers cost $75 and I'm having the woofers re-done for under $100 including shipping. So in the end I'll have a pair of AR91s for under $250. I bargain if they live up to what I've been told about them. YMMV

For many of the speakers I've recapped I like the Carli caps from Madisound. Very cheap and very good. I do plan to try the Erse PeX on a future project. Roy recommended them and I trust his advice in all things crossover.

Kent

2 50uF PEx paralleled would make 100uF at a cost of $11/speaker...whoops, just noticed that they are custom, with a min, quantity of 100...never mind

[JKent]

2 50uF PEx paralleled would make 100uF at a cost of $11/speaker...whoops, just noticed that they are custom, with a min, quantity of 100...never mind

Yes I should have mentioned--that was a problem with some of the PEx caps I looked at: Minimum order size. Some others were out of stock (39 and one other as I recall). A little frustrating. Anyway as I said, their premium caps did not seem "that" expensive for use in a TOTL speaker. Maybe Rob skewed my judgment when he had me recap his KLH Fives with those big red Clarity SA Caps

I do plan to use the PEx line in some future project.

Kent

[JKent]

Got the woofers back from Millersound in less than 2 weeks! They look terrific. Glad I didn't try getting that goo off myself. Can't wait to get them all put back together.
Kent

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[ar_pro]

What a fine job - they look like new!

[saad]

Ah well, to me looks like the glue should have been less and more neatly used on the woofer. Too much glue unevenly placed can change the weight of the cone with uneven distribution of vibration, hence can have some affect on the overall output detail.

Anyway, what's done is done.

[Carlspeak]

Kent:
How did those 91's turn out?

This thread seems to have peetered out.

[JKent]

They turned out very nicely and I love the sound but right now I don't have a spot for them so I'm using AR-3a's instead. Those sound great but I suspect that in an A-B comparison the 91s would have an edge.

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[Carlspeak]

I've got a pair I'm restoring now. Mucho issues. Dead tweets and mids. I've found some replacement drivers and have installed in one cab but haven't tested yet. Also found the woofer looks like it had been refoamed with a 12 inch foam that's stiffer than normal (WT2 Fs=26.4 hz). Whoever did the job added a cardboard spacer to bridge the gap between the cone and the larger, ID foam.
Will report back once I talk to the customer about the woofer and run some tests on the new drivers. The xo looks OK. Nothing looks cooked. However, I'm wondering if the refoam job had something to do with blowing the mids and tweets.

[JKent]

Good luck with that. As you can see in post #7 above, some of the caps were those crummy black and red PVC Callins type caps that always fail so FWIW I'd recommend replacing those (4uF, 8uF & 40uF). The big cans are probably fine (24uF & 100uF. Manufactured by Callins but not PVC).
Kent

[Carlspeak]

Ah well, to me looks like the glue should have been less and more neatly used on the woofer. Too much glue unevenly placed can change the weight of the cone with uneven distribution of vibration, hence can have some affect on the overall output detail.

Anyway, what's done is done.

What I see in the pic on the right in post #12 is the original glue which was put on during woofer manufacture. It was deliberately applied to the cone down past the inner edge of the foam. Why? I don't know, but that's the way it is. To remove it (it wouldn't be easy either) would also alter the cone's weight, but to the light side.

Edited by Carlspeak, 10 October 2012 - 10:59 AM.
clarity

[JKent]

Carl
I really don't know what saad was referring to. My woofers "before" were pretty sloppy but "after" being refurbished by Millersound they are perfect. The cardboard spacer on the ones you're trying to rescue sounds like a real botch job.
Kent