new acquired AR-18's

[alkermes]

Just picked up a pair of AR-18's based on the favorable comments I've read here.  I was surprised at how small they were.  I am curious to see how they compare to the older 4x's.  The vinyl wrap is in nice shape, it's actually pretty nice looking.  The crossover could not be simpler, unless they left the switch out.

I had a few questions...

1. As you can see the tweeter screws are rusty, just cosmetics but I'd like to replace them, are they are standard size? 
2. Foams need replacing, I was thinking of trying the SpeakerWorks foams as I read here that they were liked.  I'm happy to go with someone else though.
3. The foam grilles, or whatever  the material is, are actually in perfect shape.  However, they do smell darned musty from long term basement storage.  Is it safe to wash these?
4. To reseal the woofers, is it OK to use the duct sealant like for the 3a's etc.?  I have a lot of that left over!
5. Would it be worth it to replace the poly fill with fiberglass?

As a part of the restore, I will recap and update the speaker terminals to modern binding posts.

[AlgoRhythms]

Nice.  I'm very fond of these speakers.  I used AR18 as a small monitor to mix records on a pair in the 1980's. 

I would love to find a pair to restore.

They are worth fixing!

 

Michael

AlgoRhythms

[ra.ra]

Hey Rick,

Looks like a great pair - - and the earliest version of the "18". For foams, yeah, going with what was recommended in a recent thread is probably a good idea.  And yes, the duct seal should work just fine for sealing the woofer - - I'd imagine the original white foam ring gaskets are all squished up. Foam grilles...... is this the black, bevel-edge woven mesh type about 3/4" thick? The entire "Truth in Listening" brochure never mentions the material used for this series, but others will chime in. I'd guess they could be rinsed with mild solution, but be careful, they may be delicate and difficult to replace. 

On the screws, I think they might be standard 8-32 threads, but hex-drive button head cap screws are a little expensive, and I've had good experience simply "re-freshing" the originals. After removal, first a spray of WD-40 and a light wire brushing, wipe clean, then dip the head in a very thin flat black paint (thin with mineral spirits). Allow to dry, and you're good as new. Also, the capacitor - - can't recall if this version might be a 5uF or 6uF, but you know those black/red caps require replacement.

The AR-18 is a terrific speaker, and seems to be an extension of the lineage of the AR-7, which used fiberglass. Re: stuffing, it'd be hard to tamper with a good thing, but the recent thread discussing the pronounced differences in an AR-3a cabinet would make me curious as well. Try it and compare? 

Please show us the part numbers once you've removed the drivers. Nice find, great project.

[michiganpat]

cap is a 6uf unit.....

for the screws, I'd take the heads to a wire brush on a motor/bench grinder, and then re-color with a black sharpie.....

foams, get some boston acoustics filled fillet 8" foams.  the woofers originally had an open cell foam gasket around the perimeter of the foams.  I made some out of felt when I refoamed mine a decade ago, but found some foam that matches very well and build a jig to cut them out, but I haven't gotten a round to it yet.

I was lucky and found 2 pair of brand new OEM grilles on Ebay about 8 or 9 years ago for $20 ea shipped (I have 2 pair, bought at the same time. 1 pair has the tweeter switches, the other doesn't)

to seal the drivers, if the original foam gaskets isn't in good enough shape, I much prefer this gasket tape to duct seal

https://meniscusaudio.com/shop/misc/gasket-tape-100ft/

 

[alkermes]

Thanks guys for the great advice!

Here is a photo of the foam grill.  in real life it's a nice brown color.  Amazingly enough they look great.

[lARrybody]

Very nice AR 18 speakers. It appears yours are the ones with switch.  As far as the 6 uf capacitor here are the choices I have used.

Erse 6 uf caps on top (Erse).  Blue Clarity PX 6 uf caps to the left (Madisound) Carli MET 6uf caps (Madisound) (my favorite) and of course you can wire two Dayton 3uf caps in parallel (Parts Express).

All good choices. I used the boston type surrounds on mine (Rick Cobb), a little harder to fit than the JBL/Bose type but much more compliant.  I kept my original binding post, but on my 18S models with the terrible spring clips I used these.

http://www.parts-express.com/parts-express-gold-plated-banana-5-way-speaker-wire-binding-post-terminal--260-302

I have the same original foam grills as yours, but had to find a couple of the attachment disk that were missing.   I prefer the 18S models slightly over the 18 model, it could just be me. Here are the differences.

1.18 speaker used the 034 tweeter (straight leads) and the 18S used the 038 tweeter (s shaped leads)

2. 18 used 6uf cap and the 18S uses a 5uf cap.

3. 18 has offset drivers while the 18S has in line drivers.

4. Cabinets are about the same, but the 18S used a cloth grill. Woofers are close to the same.

I also have the 18B models which are also very good sounding. Have used mine with a subwoofer, but prefer them just by themselves. My favorite small AR.

  

 

 

 

 

 

[ra.ra]

Very good brief summary, LB. I know that the 18B uses the 038 tweeter and 037 woofer, but are the p/n of woofer in the 18 and 18S similar or different? 

[lARrybody]

1 hour ago, ra.ra said:

Very good brief summary, LB. I know that the 18B uses the 038 tweeter and 037 woofer, but are the p/n of woofer in the 18 and 18S similar or different? 

Thats a good question. The  AR 18B and AR18S definitely use the same square magnet 037 woofer. The woofer in my 18 looked identical, but may be a different part number. In fact the 8 in. woofers in the four AR7's I have refoamed look very much the same, but were definitely different part numbers. I will have to pull the AR 18 woofer to check. My 18 woofer has a fiber speaker gasket while the 18S and 18B use a plastic trim ring. Maybe Alkermes can post the part number on his. I bet they are different, maybe the same as the AR7.

One more question. How would one figure out how much fiberglass to use in relation to the poly fiber fill used originally. By weight or by cabinet volume?  Maybe just stuff it till its full.   

 

 

 

 

 

[ra.ra]

LB, I just thought you might know about the various woofer p/n's but since not, I began digging thru a stash of files I've kept for reference and came up with this portion of drawing for p/n 200001 (is this the so-called "universal" 8" woofer?) which notes the AR-18 model and several others. 

Re: AR-7, I have two pairs as well, but I'm now kinda curious about yours. One pair of mine has original woofers (flat dust cap) dated '72, and the AR-7 assembly drawing notes this as p/n 200001-1. My other pair has the Tonegen replacement woofers.

[Jeff_C]

19 hours ago, alkermes said:

Here is a photo of the foam grill.  in real life it's a nice brown color.  Amazingly enough they look great.

They appear to be the original open cell reticulated foam grilles and they do look great. If you can delicately rub your thumb along a bottom edge of the foam grille and do not get any crumbling away of loose cells, they should be good for a few more years at least. Keeping them away from UV light may help to preserve them more. I wonder why the woofer foam surrounds have rotted when the grilles have survived. As these are now vintage I think I would put a full cover over the speakers when not in use after they have been restored. That may help preserve those grilles as much as possible. They will be very difficult/impossible to replace.

I had similar foam grilles on the AR-16 (they are from a similar era, mid to late 1970s). The grilles were exposed to quite strong sunlight in the environment where they were used (well at least when the sun shone here in the UK). I remember the grilles lasted about 10 years before I gave up on them and threw them out. In the latter years of their use I used to see black foam crumb on the floor beneath the speakers. It became a weekly job to hoover it up. When doing the 'thumb-crumb' test dislodged too many foam cells from the grille I threw them away. Operating the speakers without the grilles on the woofer foam surrounds were then getting a good deal of sunlight exposure but they lasted a further 7 years before the speakers had to be 'retired' in 1993 due to woofer foam rot.

During the 10 years lifetime of the grilles I used to wash them occasionally in a bowl of warm water and washing up liquid, just gently squeezing them with the palms of my hands so that the detergent could work to dislodge household dust etc. Then rinse them in clean tepid water and then lay them out to dry on newspaper before attaching them back on the speakers.  I do not believe that process shortened their life.

[JKent]

1 hour ago, Jeff_C said:

They will be very difficult/impossible to replace.

There is an outfit on this side of the pond that makes replacements: http://www.foamspeakergrilles.com/

I had some made for my Cizeks but I think another, more economical solution would be to fashion some frames and cover with cloth when the need arises.

-Kent

[michiganpat]

2 hours ago, JKent said:

 but I think another, more economical solution would be to fashion some frames and cover with cloth when the need arises.

-Kent

that's what Glenn (GD70) did on his AR12's, and they came out great.  I measured the bevel on my 18's grilles so he could match it on the frames....

[alkermes]

Lots of interesting responses, this has been fun, and I haven't even played them yet!

The surrounds were ordered last night and went out in the mail today, so they should get here in a few days.  I'll post the driver #'s when I pull them out of the frames.

I have some of the black Erse caps, I'll use them as I have them on hand.  The cap is a 6uf.

The grilles pass the thumb rub test :-)   I  think I may just try airing them outside, out of the sun, and see if the smell dissipates on its own.  Good to know about the UV.  Direct sustained sunlight seems to be best for plants alone.

[Jeff_C]

12 hours ago, JKent said:

I think another, more economical solution would be to fashion some frames and cover with cloth when the need arises.

I made cloth covered wooden frames for mine. I only use them as covers and leave them off for listening. The original foam grille was extremely acoustically transparent, but the cloth (even to my aging ears) cuts out a noticeable amount of HF response. YMMV. The foam was machined out to be quite thin where the drivers are placed, that may have helped with transparency.

I doubt that any foam grille replacement would have the sculpted out foam where the drivers are placed, but if they can do that as well for reasonable cost then great. That is particularly what was on my mind when I said they may be "difficult/impossible to replace". If I could replace the foam grilles for reasonable cost I would like that because it puts the speaker properly in its time zone of mid to late 1970s when many speaker manufacturers used foam grilles.

 

[alkermes]

5 hours ago, Jeff_C said:

 If I could replace the foam grilles for reasonable cost I would like that because it puts the speaker properly in its time zone of mid to late 1970s when many speaker manufacturers used foam grilles.

 

Jeff, your comment about foam grilles reminds me that you are probably familiar with the Mission 700's.  I have a pair of one of the earlier versions, they used foam too, but just a slab, not formed like the 18's grilles.

The speakers are of a similar size, but the Missions are ported and the woofer and tweeter are inverted....very different philosophy, but united by foam.

[ra.ra]

File this under AR minutiae. The pic attached is from a very nice pair of 18's currently selling online, and what surprised me is that both speaker cabinets show the same serial number. Unlike the other speaker models from the Classic era, the AR-18's precursor, the AR-7, were sold as pairs. The AR-7 was typically packaged two speakers per carton, but each AR-7 cabinet had its own unique serial number. Product catalogs suggest that the AR-17 and AR-18 were also packaged two per carton, but perhaps the method had changed for issuing serial numbers? What is the s/n on the OP's second cabinet?

 

[lARrybody]

Both my AR 18's have the same serial number (AR18J 057892). 

On 3/29/2017 at 0:21 AM, ra.ra said:

 

LB, I just thought you might know about the various woofer p/n's but since not, I began digging thru a stash of files I've kept for reference and came up with this portion of drawing for p/n 200001 (is this the so-called "universal" 8" woofer?) which notes the AR-18 model and several others. 

Re: AR-7, I have two pairs as well, but I'm now kinda curious about yours. One pair of mine has original woofers (flat dust cap) dated '72, and the AR-7 assembly drawing notes this as p/n 200001-1. My other pair has the Tonegen replacement woofers.

 

Pulled a woofer from one AR 18 and it has the part number 200001-1 as you suggested. Cloth dust cap like the AR4X, not the plastic one like on the 037 woofer of the 18S/18B.

It turns out I have three sets of AR 7's. All with the same woofer with the flat dust caps.

The interesting thing that they are all slightly different. One pair has wood veneer and front wired 1 1/4in. tweeters. One has rear wired tweeters with the connection plate in place and the other with rear wired tweeters with no connection plate. Both of the last two are vinyl covered cabinets but different finishings and switches on the back. 

I also pulled a woofer from a AR6. No apparent part numbers, but looks very much like a AR4/AR4xa woofer with a foam surround. It does have the date September 29, 1971.

  

[ra.ra]

Thx, L-B, all very interesting, and thx for the hands-on report. Will comment further later, am on the run now. One curious observation: is the AR-6 alnico woofer wired correctly? - - I've always assumed the factory red "X" on metal basket denoted positive "+" terminal.

[lARrybody]

I believe wiring is correct. I don't know what that red mark is about. Here is a photo of another AR6 woofer that Roy posted 10 years ago. They are wired identically. Notice that the wires are soldered on. Most AR woofers have a red dot or plus sticker, mine must of fallen off.

[ra.ra]

Apologies to alkermes for temporary hijack, but......

Attached is pic of the alnico woofer from my 1971 AR-6's. Similar to Roy's pic, note how the red wire is attached to the terminal with the red sticker or the red/orange "X" mark (even if one is "left-hand" and one is "right-hand") while your woofer shows the black common wire attached to the "X" terminal. Confusing?.........you bet. 

[RoyC]

Until sometime in the mid-70's AR woofers varied as to the position of the positive and negative terminals. The red "X" mark on the basket and the + label usually designate the positive terminal, but it is important to note the original connections, and check the polarity, as part of any restoration. Identifying polarity is easy to do with a 1.5v battery.

Polarity confusion can also be the result of any previous work where it was not taken into consideration upon reinstalling the woofers.

Roy

[lARrybody]

Stopped on the way home from work and picked up a 9 volt battery. The wiring is correct, cone moves out when connected red wire to positive and blue wire to negative. Cone sucks in when reversed.

I agree that this thread needs to be about alkermes AR18's. When he gets them recapped and new foam I want to know what he thinks. To me they are impressive small speakers. I don't remember if he said he was going to keep the original binding post or replace them with modern ones. Here is what I cobbled together so I may keep the speakers original and take advantage of modern banana plugs. 

 

[ra.ra]

Apologies for thread derailment. While I read Roy's comment and looked again at L-B's AR-6 woofer, I seemed to recall a thread long ago that documented another AR woofer that had terminals labelled incorrectly, and even one that had both terminals labelled "+". The battery test is always the final arbiter.

 

[alkermes]

Detours are always welcome!

I just started working on the woofers, the woofer part number is 200001-1 as in L-B's photo above.  I also pulled the tweeter, part number is 200014-3. 

After I get the foams on I'll give them a spin with the original caps to test them out.  I was planning on replacing the terminals, but just received a missing nut & washer from Kent along with a few other goodies, so I may keep them original.  On the other hand, these speakers are so easy to work with, it would be easy to swap them around any time.

[alkermes]

OK, they are done.  I used them for a few days after the re-foam with the original caps in place.  I have had the new caps in place now for a few days.  The original Callins caps actually measured very well, the ESR was very good, they did not need to be replaced for wear and tear reasons.

The speakers perform quite astonishingly well.  With my back turned to them, I imagine they are at least 2x as big as they are.  If I had a small space and had to pick one set of speakers to live with, these would do nicely.  I have been mentally comparing them to the 4's and 4x's I owned, as being roughly the same size.  I admire the 4 series for doing what they do, given the era, but the 18's are a big step up (in my humble opinion).  I was never really satisfied with the 4's as I am with these.

Here is the re-foamed speaker with the tweeter screw heads cleaned up, and a photo of the crossover with Erse 4uf & 2uf caps paralleled.