AR12's Restored-A few Pics

[fedeleluigi]

On ‎11‎/‎11‎/‎2017 at 5:45 AM, GD70 said:

The last pics showing the mid refurb and woofer shimming for the new surrounds. It was odd that there's two dust caps. I assume the domed cap was to modernize the look.

I think this pretty much covers the project.

Glenn

 

Hi Glenn,

Excellent job and thank you for sharing it!

Could you please tell me what is the voice coil former material used in the woofers (200004-2 ) you shimmed? In one picture it seems aluminum, in the other one it seems paper or nomex. I'm interested in it as AR began to use aluminum for its voice coil at some point (I suppose about the middle or the end of 1977) and   in one of your woofer is printed the manufacturing date (33th week of 1977) .

Thanks.

 

Luigi

 

[GD70]

19 hours ago, fedeleluigi said:

Hi Glenn,

Excellent job and thank you for sharing it!

Could you please tell me what is the voice coil former material used in the woofers (200004-2 ) you shimmed? In one picture it seems aluminum, in the other one it seems paper or nomex. I'm interested in it as AR began to use aluminum for its voice coil at some point (I suppose about the middle or the end of 1977) and   in one of your woofer is printed the manufacturing date (33th week of 1977) .

Thanks.

 

Luigi

 

Hi Luigi!

Thanks!

If I remember correctly, it was a stiff paper or nomex, but I could be dead wrong too! I don't remember it being a metal material though.

I'll refer this to Roy C. He may chime in on this one.

These were a fun project!

[fedeleluigi]

Hi Glenn,

I hope Roy C. can chime in as he uses to shim woofers when refoaming them.

Thanks again

 

Luigi

[RoyC]

11 hours ago, fedeleluigi said:

Hi Glenn,

I hope Roy C. can chime in as he uses to shim woofers when refoaming them.

Thanks again

 

Luigi

I don't know precisely when AR transitioned back to metal voice coil formers, but it is logical to assume the 10 inch woofer vc was changed over about the same time as the 12 inch woofer. I believe the earliest such 12 inch woofer I've seen had an early 1977 date stamp.

As a point of interest, the earlier type of 10 and 12 inch AR woofers with cloth surrounds had metal voice coil formers. When AR went to foam surround woofers, around 1970, the vc former was changed to paper until the mid to late 70's period under discussion. I've often thought that AR's move to the foam surround type of woofer was more motivated by cost savings than performance improvements.

Roy

[fedeleluigi]

On ‎25‎/‎11‎/‎2017 at 8:10 PM, RoyC said:

I don't know precisely when AR transitioned back to metal voice coil formers, but it is logical to assume the 10 inch woofer vc was changed over about the same time as the 12 inch woofer. I believe the earliest such 12 inch woofer I've seen had an early 1977 date stamp.

As a point of interest, the earlier type of 10 and 12 inch AR woofers with cloth surrounds had metal voice coil formers. When AR went to foam surround woofers, around 1970, the vc former was changed to paper until the mid to late 70's period under discussion. I've often thought that AR's move to the foam surround type of woofer was more motivated by cost savings than performance improvements.

Roy

Thank you Roy,

I thought that the change had occurred later, around the middle of 1977. Anyway, one of the pictures posted by Glenn shows a woofer manufactured on the 33th week of 1977 and  one of his woofers would seem to have a paper voice coil just like he remembers.

Imho,  the paper voice coil former used in the 12 inch woofers from around 1970 to around 1977 and the use of a  not bumped back plate was the "Achille's heel"  of those excellent woofers.

Apart from the possibility of a hard bottoming for the flat back plate of the magnet , Imho,  at the voice coil "collar" (I mean the former space between the cone and the first voice coil winding) the paper former  was not "strong" enough to bear the big forces caused by the wide and  violent  oscillations  of the heavy cone (at high volume) during many years .

I do think that at AR they never imagined  that there would  be lovers and enthusiasts for their speakers after more than 40 years!

Luigi

 

 

 

[GD70]

14 hours ago, fedeleluigi said:

Thank you Roy,

I thought that the change occurred later, around the middle of 1977. Anyway, one of the pictures posted by Glenn shows a woofer manufactured on the 33th week of 1977 and  one of his woofers would seem to have a paper voice coil just like he remembers.

Imho,  the paper voice coil former used in the 12 inch woofers from around 1970 to around 1977 and the use of a  not cup shaped back plate was the "Achille's heel"  of those excellent woofers.

Apart from the possibility of a hard bottoming for the flat back plate of the magnet , Imho,  the paper former at the voice coil "collar" (I mean the former space between the paper cone and the first voice coil winding) was not "strong" enough to bear the big forces caused by the wide and  violent  oscillations  of the heavy cone (at high volume) during many years .

I do think that at AR they never imagined  that there would  be lovers and enthusiasts for their speakers after more than 40 years!

Luigi

 

 

 

I've cranked these pretty loud, with tracks with deep bass and have yet to bottom out the VC's. 

Getting these from the original owner, I'd adventure to say he didn't push them much.

Glenn

[fedeleluigi]

On 29/11/2017 at 4:29 AM, GD70 said:

I've cranked these pretty loud, with tracks with deep bass and have yet to bottom out the VC's. 

Getting these from the original owner, I'd adventure to say he didn't push them much.

Glenn

Hi Glenn,

I was referring to the 12 inch woofer. The moving mass of the 10 inch woofer is much lighter and its Xmax is smaller  than the 12's. Moreover the 10 inch ferrite woofer has a bumped  black plate. For all these reasons the crack of the voice coil support is rather rare in AR 10 inch woofer. 

As I do not usually shim woofers when I refoam them, I do not know when AR exactly changed the former for its voice coils. I usually disassemble woofers only when their voice coils or spiders are broken.  Anyway in some 2ax 10" alnico woofer using foam surrounds I found NOMEX. They were dated about 1972.

Nomex is a meta-aramid material developed by DuPont in sixties and is  completely different from paper. It seems plastic.  I do not know if AR continued using it also after the indroduction of the ferrite magnet for the 10 inch woofer. This is also why I asked you what material you had found when you shimmed your woofers.

Later in some date of 1977 AR began to use aluminum for all its woofer voice coils. 

As regards AR 12 inch ferrite woofer manufactured from about 1970 to 1977 untill now I have never found Nomex former (but only paper former) in their voice coils . 

 

Luigi

 

 

[EemZee]

On 11/10/2017 at 11:45 PM, GD70 said:

The last pics showing the mid refurb and woofer shimming for the new surrounds. It was odd that there's two dust caps. I assume the domed cap was to modernize the look.

I think this pretty much covers the project.

Glenn

 

Nice restore. I have AR-12s.

[GD70]

14 hours ago, EemZee said:

Nice restore. I have AR-12s.

Thanks! There were an enjoyable project.

Are you the original owner, and what condition are they in! Still have the original foam grills?

Cheers, Glenn

[GD70]

I've been listening to these a lot the last couple weeks, and I must say, they are spectacular. Gobs of deep tight bass, a wide and dimensional soundstage, and the highs are crystal clear without fatigue.it really is a shame these were only a one year wonder.

Ok, I'm done now, back to the music!

[david]

Hi, as a keen reader of these pages and other AR12 owners messages and thoughts,

I would like to share the AR12s I was fortunate to acquire in 2014 from the UK Ebay website. They came in the original AR cardboard boxes, which were quite large! Also the original metal stands as shown in the photos. The DIY replacement foam grilles were disintegrating and as can be seen from photos, the previous owner when he installed these, basically glued in some small wooden strips to keep the foam proud of the tweeter and mid drivers. The mid drivers were in need of refoam. The wooden cabinets were in superb mint condition and highly polished. The woofers had been replaced with non-AR 10 inch.

These were a pair of "managers specials" - manufactured in the UK - and purchased by one of the managers [Mr Weiger] working at AR. They came with a bit of documentation [in-plant shipping tally/ one of the labels originally glued to the back of each spkr showing serial number (matches tally sheet) and finish (walnut)/ various labels "Genuine Wood Veneer" etc] I have attached. Also attached are photos of the speakers, the full Owner's Instruction Manual (pages 1-27 plus covers) a colour two page publicity and spec sheet from AR, a photocopy that has turned a bit greenish due to age of another version of this and various price lists for the AR range from 1976 and 1981. I hope thiese images will upload OK but if they don't this time I will try again later.

The photos show the AR12s following refurb of the mids (which was very tricky) the purchase of replacement grilles from vintage_ar. The speakers work great but the bass response isn't tight or fast enough I think because it really needs the original woofers to be refitted. I will try a pair of woofers from an AR90 at some stage.the tweeters of the AR12 I was told by vintage_ar are unique to this model - luckily these work fine, but I also have 3 more in a box just in case! plus two spare mids - just in case!)

I have them in the middle of the lounge (not against a wall) and they sound great in that position even if not ideal. I also have AR91, AR90 and the AR162 "Spirit" model. The sound quality is -I am feeling - somewhere between the AR 90s and AR162 - the latter which are good looking tower boxes  with coupled 8" woofers and are lively entertaining speakers with great presence and sensitivity if built to a budget in the last years of the company. I would say the AR12s are in the same mould if more refined and more audiophile with of course much better build quality all round.

Cheers David

 

Here goes with the attachments

[david]

Here is the Owners Instruction Manual! As you can see I have got the speaker stands round the wrong way! Story of my life.

Cheers David

[lARrybody]

I too recently found some AR 12s. They also have replacement non AR woofers,but the correct and fully functional tweeters and mids. I can't believe how good they sound,even with replacement woofers. I believe mine are also UK built.  Do yours have the speckled paint on the backs?  Peaked at the crossovers and they appear original, yet they sound awesome.

 

[david]

Hi larrybody and all

You seem to have the neat looking foam grill which is a lot cleaner and tidier, and more in keeping with the 1970s, than the cloth grill. The AR 92 has a 10 inch woofer and when I get time i will swap those replacements out to see if it makes any difference to the bass response. Overall I am very pleased with sound and money spent. Hope the documentation is useful. Will also need to take out those wood strips (carefully!!) so the substitute grills can fit better. Haven't gone into the insides! The back is speckled like most models from that era.

Cheers David (You don't have to have a monster amp to get good levels out of them either)

On 13/11/2017 at 1:35 AM, GD70 said:

Hi Lakecat,

Yes, they do sound excellent. They have a more modern sound if that's a way to describe them over the 3's. Maybe that's the more forward mids and highs, not that the 3's are lacking, just a different presentation.

It is curious why this was a one year only model. Whatever, it makes them all the more unique and special.

Glenn

 

On 13/11/2017 at 3:29 AM, lakecat said:

(I have retrofitted grills on a frame obtained from vintage_ar which look very smart but not half as good as the original 1970s "cool" foam grills when they were new.)

Dave...have pics buried in here somewhere but I did the grills to match the 3a. Foam just doesn't do anything for me and is fragile so thought I would keep in the family. Renewing pics in case anyone is interested.......:)

 

On 13/11/2017 at 1:42 PM, lakecat said:

(Hi Lakecat, I see you went for linen oatmeal grills - that looks great. The cabinets look really good - oiled? What is the veneer? Walnut or teak? The original woofers is something I have to do to get that bass you describe. Cheers David)

 

Thanks Glenn....I had some of the lambswool material here and saw the foam; if available; was going to be over a hundred bucks....so decision was more being cheap than anything!..lol.

David...thanks. The grill material is the lambswool linen that is used for the AR3a. The veneer is the standard walnut that was sanded and stained with Howards....then two coats of satin poly sprayed. These speakers were a great discovery as I never even heard of the 12's until I saw these on CL. I did some research online and saw they were highly regarded so went to look at them. They were missing the grills and mids had the surround rot but woofers had been redone and cabinets were in great shape. Older guy had them that he had purchased new so original owner that was downsizing and moving. Best part...he had a $25 price tag on them!...:) 

 

 

[lakecat]

7 hours ago, larrybody said:

I too recently found some AR 12s. They also have replacement non AR woofers,but the correct and fully functional tweeters and mids. I can't believe how good they sound,even with replacement woofers. I believe mine are also UK built.  Do yours have the speckled paint on the backs?  Peaked at the crossovers and they appear original, yet they sound awesome.

 

Hi Larry.....personally, I think it's the midrange in this speaker that makes it sound so good....plus matched to that good ole bass AR is famous for. I was like you when I heard it for the first time.....just shocked in good it sounded. 

[DavidDru]

Lucky once again and acquired a very nice pair of the AR12's today from the one and only owner since he purchased them new for 10% off list at $450 in March of 79.  The purchase receipt and brochures and manual all come with these so that is cool.  Serial numbers are 2 numbers apart.  The cabinets will require very little work but new grilles are needed.  All the drivers interestingly enough are factory replacements.  He told me he thought he had them replaced around 1990 and right before they were no longer available.  Phew!

All of these drivers need the usual age-out attention, but all work.  Woofers just need new surrounds as do the mids.  Tweeters and mids need the outer plate foam pieces and I hope Glenn can help with those.  Hey buddy.

Will get a recap too of course.  40, 20, 10 and 6.

The ferro fluid thing is interesting.  I recently replaced the ferro fluid on some KEF104/2 and it was pretty straight forward easy as long as you know the amount.

Check out the photo with the teledyne acoustics sticker on the bottom of the rear plate and how it was meant to cover the AR logo.

I hope I summarized the approach well enough.  I gathered together this strategy after reading various threads on the 12's here and at AK.

 

  

[GD70]

Hi David,

Very nice set of 12's. These will be an easy restoration. The woofer dust caps are cosmetic and easy to pop out when you cut them and the flat caps underneath for shimming. I always leave a little attached to act as a hinge so realignment when regluing is easy.

I sent you the mid surround info a week or two ago.

I'll get to your mid and tweeter foams in the next couple weeks. Vacation coming up etc...

Cheers, Glenn

[briodo]

My compliments to the author on this restoration.  Great pictures and excellent details of how to bring back a truly rare classic.

I have a pair of 12's I have done minor repairs on since they were purchased 5 years ago, a craigslist score for less than $100.  The 10" had been refoamed but the caps were the red and black NPE that I replaced with Dayton NPE.  I assumed the midrange was good since it does play but now looking at Glenn's close ups of the foam replacement makes me think mine have been "repaired" at some point with some coating due to the foam disintegration.  I have a couple of pics attached and would appreciate feedback for those of you who have seen the correct foam material in place.  The midrange drivers do not appear to have been touched, but the glossy surface tells me these are not foam surrounds at this point.

See below.  I tried to get different views on single driver, but the other looks identical.

Do these appear correct? 

 

[GD70]

Thanks, much appreciated! You got a great deal on yours!

Yes, yours are original, except the surrounding foam trim is gone, and the basket was painted black.

The foam surrounds are original, clearly repaired with what looks like a thin application of silicone. They won't last much longer.

I would do a recap as well. Those black caps are crap and out of spec by now.

Cheers, Glenn

 

 

[briodo]

1 hour ago, GD70 said:

Thanks, much appreciated! You got a great deal on yours!

Yes, yours Re original, except the surrounding foam trim is gone, and the basket was painted black.

The foam surrounds are original, clearly repaired with what looks like a thin application of silicone. They won't last much longer.

I would do a recap as well. Those black caps are crap and out of spec by now.

Cheers, Glenn

 

 

Thanks Glenn, found the replacement parts using your parts list and have them on order.  Will spend time figuring out alignment as they do not appear to require shims.  Will invest some time learning technique. 

I did replace the red/black original caps with Dayton NPE last week and found a whole new speaker to listen to.  Learning that craigslist purchases still require cracking the case open even thought someone replaced the foam surrounds.

Just want to share my appreciation for the details on your rebuild.  Provides all key points to restore a pair of AR12's to like new condition.  The grill specs alone cover a whole list of systems from that era.  Original foams from that era are hard to find, and your replacement design actually looks better than the foam, IMHO.

Kudos to you

[GD70]

I'm glad the thread is helpful, that was the intent! I'm in agreement with you regarding the grills. It wasn't intensional, but I like that they are slightly sheer, revealing hints of the drivers. 

Enjoy your 12's, they're special speakers.