AR 10pi woofer problems

[lARrybody]

I have been looking for a set of 10pi speakers for a while now. Yesterday I went up to Chicago to help my son wall mount a TV and set up his home theater. I came home with a set of MK1 10pi's. You might have seen them listed on the auctions site. They were in my watch list for over two months with no takers. Tuesday I finally contacted the seller and ask what his bottom line was on them. I explained that I did not want to insult him with too low a offer. He replied that they were not his and he was selling them for a friend. He said I should make a offer  and he would pass it on to the owner. They are by no means pristine, more of a project set. The woofers did not look quite right with large dust caps. I made him a substantially lower offer and to my surprise it was accepted. Here they are today sitting on my patio table.

I pulled one of the woofers to see what they were. They are actually the original A4 woofers that someone has refoamed and added oversize dust caps and painted the cones with some paint/glue type mixture. They really slopped it on there thick.  My question is what type of solvent or paint striper and what technique  should I try to clean them up without damaging the cone too much. Maybe the answer is to get different woofers. Here are some close up pictures.

++

[JKent]

Great find! Those are beautiful speakers!

My first thought is, just play them a while and see how they sound. I remember years ago our friend John at M-Sound recommended using (much) larger dust caps for re-foams and also coating the paper with a dilute solution of his white glue. That does look pretty thick though. The problem is getting the coating diluted without disolving the paper cone. I'd be tempted to try a soy or citrus based paint remover. There are also paint removers made specifically for latex (i.e. water based) paint. I wonder if one of those might work.

As a last resort, send them to Bill LeGall. He did a great job of cleaning up my AR-91 woofers that had a solvent-based glue slopped all over the re-foam job.

[RoyC]

The foam surrounds are also glued to the underside of the cone, which was never done with this woofer.

It will probably be very difficult or impossible to remove whatever was applied to the cones, but I would still try to use them after replacing the foam surrounds, and cutting/removing the oversize dust caps close to the cone with an exacto knife. You can still use smaller dust caps if the cones are ok underneath.

Roy

[fedeleluigi]

@lARrybody the DC resistance you measured (3.9 Ohm) is not correct for the 200003 woofer (it should be about 2.6 Ohm +/- 10%).  If your digital multimeter is accurate  the tinsel wires could have some problem or the voice coil could have been replaced with a not appropriate one.

The woofer basket looks like a 1975 one therefore if the the woofers are the stock ones the original tweeters were replaced with later versions since the tweter domes/suspensions were yellow until the first months of 1976 and later black. In any case there was no foam on the tweeter flange for the AR-10 Pi MKI. The original tweeter used in the AR-10 Pi MKI and AR-11 MKI are shown in the file "Restoring the AR-3a" (Fig. A.21 and A.22).

[ra.ra]

Hey Larry, that's a great story - - congrats on finding those rare speakers (wow....veneer on backside!). When you get a chance, tell us a little about the mids and tweeters, and of course, the cabinets, grilles, badges, etc.

Too bad about those woofers being slopped up, but you'll get them back in good shape after proper attention. Trying to revive the cones seems to be the biggest challenge. According to product specs, the statement above about DCR is correct - - original factory range states 2.3 to 3.0 ohms. And Roy's comment about foam placement is also confirmed by 003 woofer drawing, which also shows 5/8" outside dimension on the woofer roll. I may be mis-reading your photo, but it appears that the foams have a radial splice which would suggest incorrect foam to begin with.   

[BGRoss]

Hi... new member and 1st post. I have little to no experience with AR speakers. Been mainly a Rogers/Linn/Proac/KEF guy for many years; just like what they do across the pond. I did however recently pick up a set of AR 10pi in truly extraordinary condition. Thy came from a church rectory and it looks like the padres took special care of them. They are early gold badge, yellow tweeter models that play marvelously. They do however have what appears to be two different woofers. One has a silver basket and one has a black. The fathers also sent them out at one point for a terrible reform job; easy enough fix. I really want to put these together the right way and give them to my father in law for his 80th birthday. He lusts after my gear whenever he's over and I want to give him these with a wonderful Tandberg 3012 & 3011integrated & tuner. I'm going to take the LF drivers out for a look later this week & will post some pics but please, what is the exact model woofer that goes in these boxes? They really are special and 100% complete with foam grills in excellent condition, all badges intact and original owners manual. Any help I can get is welcomed. TY - B

[BGRoss]

Good God! This site has more information on AR then I would have ever expected... what a wealth of useful insight and experience, wow ?

[lARrybody]

On 7/27/2019 at 1:56 AM, fedeleluigi said:

the DC resistance you measured (3.9 Ohm) is not correct for the 200003 woofer (it should be about 2.6 Ohm +/- 10%).  If your digital multimeter is accurate

Fedeleluigi, that turn of the century multimeter was wonkey. It has been replaced with a new one. Searching the internet I found images of the original yellow dome tweeters. I have MK1 AR 11's, AR 12's and and these 10pi's, all with black dome tweeters. Not sure when AR switched to the black ferrofluid examples. My MK2 AR 11's definitely have the 2000011 tweeters.

I just received some replacement used woofes from a auction. I thought they would be A5 woofers because the outside baskets are silver and not black like the original ones currently in the 10pi's. To my surprise I think they are actually A4 woofers because of the dust caps. The seller also included the  original screws, gaskets and fiberglass sheets from the AR 11 they came from. The screws are philips heads and the dust caps have lips. if they were A5's they should of had square drive screws and flush dust caps. Also the dates of the fourth week of 1976,( the originals have a date of the 51st week if 1975) lead me to believe they are A4's. I couldn't be happier and after they are refoamed they are going in the 10pi's.

BGRoss

Welcome to the CSP. Those sound like some really special AR10pi's. I wish I had those original tweeters. Post some pictures of your woofers and let us try to identify them. I have been around here several years and learn new things almost every week. You found the right spot for information you can take as the truth.

[BGRoss]

I will soon, thanks for chiming in. I haven't had a chance to play them at length but they're really robust with a massive presence. I got used to my mid 80s 11ohm Rogers LS3/5As that I just sold so, small box syndrome at work with me these days. The 10pis really are amazing although I'll be passing these on at some point too once they are 100% correct. Looking forward to your opinion and advice.

[Pete B]

Great info, first I've seen of the test specs, thanks.

[BGRoss]

So - here are some pics of the 10pi... still no time to take out the drivers but maybe over the weekend. Cabinets are very clean with the exception of a few light scratches on the bottoms. Some sun fading on one as they probably sat in the same spot for 40yrs, lol. Anyway, need to know which one of these is the right LF driver. Pretty certain they're both the same actual unit just from different batches. One must have been replaced along the way buy just curious as to weather the unpainted basket or black basket would be the one that was age appropriate for the serial #s are A 02722 (unpainted) & A 02902 (black). Thoughts?

[Aadams]

37 minutes ago, BGRoss said:

Anyway, need to know which one of these is the right LF driver.

There are others here with more expertise but being summer the CSP is less active so I will pitch in for now.    Tweeters and mids appear identical and are probably original.  Cabinets are nice.

The woofers are different models.  The woofer below is the later one but I cannot see if it has a skiver ring (looks like leather) or not.  You will need to remove them to find out which model.  If those are original grill covers they couldn't have spent much time in the sun because they are not rotten. 

The surround replacement job on the woofers is not quality work.  Specifically, they are incorrect surrounds and have been spliced which, aside from looking sloppy,  is just wrong considering the correct surrounds are easily acquired. If they were not shimmed when they were spliced and  refoamed they could also be misaligned.   You might ask for specific advice on the best way to apply a new surround  to correct a recently cured surround because it is not easy to remove that glue without damaging the cone edge.   

Download the AR3 restoration guide.  The appendix has pictures, dates  and identifiers for all of the AR drivers used in this model. 

Aadams

 

[BGRoss]

Thanks Adams, Yeah I know... the Padres prob did the reform themselves; it's a bad job but I already ordered the right replacement foam kit from Parts Express. Going to replace all the rusted screws as well with flat heads maybe in brass... will toss a couple in there and see how they look. The "skiver" appears to be cork (?). I'll replace those as well and maybe someone here can help me source those. Did these have a foam/felt acoustic lens on the tweeters? Cant find any supporting pics that say they do on this model. Parts Express has those too. Can't really speak to the foam grills but they appear original and even have impressions for the particular drivers pressed out on the insides. I have to say I'm going to go all out on these considering I got them the right price. Any advice on cleaning the tweeters or should I just leave then alone - seem very delicate. I also promised the Fathers I'd say a couple of novenas for doing me such a solid - maybe I'll keep them a while and see how they play with some different gear other than the Tandberg.

[BGRoss]

I'm going to have Brian Salazar at Holt Hill Audio here in Massachusetts do the reform... he's the best I've seen. His work on Altec, AR, ADS and other vintage speaker brands is second to none. I'll take the drivers out and bring them to him.

[Aadams]

12 minutes ago, BGRoss said:

 it's a bad job but I already ordered the right replacement foam kit from Parts Express.

I can't recall Parts Express ever being cited in these forums as the source for the correct surrounds for AR12". 

If you remove the skiver you are creating more problems for yourself. If your woofer has a usable skiver use it and don't try to make one. You can't purchase replacement skivers.  If it doesn't have a skiver check the model number because the latest generation woofers didn't use a skiver. 

If originality is important or you plan to resell you should keep and refurbish those machine screws or purchase new ones.  Flat heads are flat wrong especially if your are thinking about wood screws.

There were at least 2 generations of 10Pi.  I think the later ones may have had acoustic foam on the tweeter.  My advice for these would be if the tweeters and mids are working don't mess with them. 

If you want the best advice here you will be asked to send images after you extract the woofers.

Adams

[RoyC]

1 hour ago, BGRoss said:

Thanks Adams, Yeah I know... the Padres prob did the reform themselves; it's a bad job but I already ordered the right replacement foam kit from Parts Express. Going to replace all the rusted screws as well with flat heads maybe in brass... will toss a couple in there and see how they look. The "skiver" appears to be cork (?). I'll replace those as well and maybe

The "skiver" is another name for the spider, the fabric suspension at the base of the cone. It is not the surround's mounting ring. Your woofers most likely need only the correct surrounds. Don't mess around with anything else.

The Parts Express foam replacement is acceptable.

Roy

[Aadams]

1 hour ago, RoyC said:

The "skiver" is another name for the spider, the fabric suspension at the base of the cone. It is not the surround's mounting ring. Your woofers most likely need only the correct surrounds. Don't mess around with anything else.

The Parts Express foam replacement is acceptable.

Roy

Hello Roy

Consider me corrected.  I thought the rings were called skivers because the early ones look like skived leather .

Adams

[ar_pro]

Adams is absolutely right - it's important to have the correct mounting bolts for the drivers - brass is too soft. 

A little bit of rust isn't unusual at all - just sand the heads lightly to remove the oxidation, and spray with some black Rustoleum.  A good method is to push the bolts through holes in a piece of cardboard, so as to avoid getting paint on the threads. If you leave your speakers on their backs, you can remove all of the bolts at once, with no danger of the drivers coming loose. Take care when re-installing the bolts that you don't dislodge the anchoring t-nut - don't lean into the screwdriver.

Those do look like the original sculpted foam grilles - congratulations on a very nice pair of speakers!

[BGRoss]

You guys are all great! Really appreciate the help... I’d never heard the term “skiver” before so good to know I now have it straight. I would never myself play around with the innards of any particular speaker; just not confident enough. I do trust HHA and know they refoam and rework the drivers appropriately. As for the screws also good to know. May look aesthetically better but wouldn’t be as intended. I will refurbish or replace with the right screws. Other drivers all work marvelously so will indeed leave them be. - Brian

 

[lARrybody]

Very nice speakers indeed. The black woofer is definitely a original A4 driver. The silver woofer could be A5 out of the MK2 series. Then again it could be out of a AR9/91 speaker. If it has a square magnet it could be from a AR 58S. The only way to know is to see the backside of the woofer. Those look so nice all you may need to do is identify the odd woofer and re-foam.  I am a big fan of Parts Express, but when it comes to surrounds Rick Cobb is my goto guy to make sure I get the correct compliant parts. I have a pair of AR 11in.replacement foams from Simply Speakers that I chose not to use after comparing them to the surrounds Rick sent me.  Let us see the backside of that woofer.

 

 

[BGRoss]

Thought I’d show off the finished product,... they are now again extraordinary in every way and play gloriously. New owner is ecstatic over their fit, finish and sonic footprint.
Holt Hill Audio is without question the finest vintage speaker resto outfit in the Northeast;  B. Salazar is an exceptional talent.

[gpzy]

On 8/9/2019 at 6:22 AM, BGRoss said:

So - here are some pics of the 10pi... still no time to take out the drivers but maybe over the weekend. Cabinets are very clean with the exception of a few light scratches on the bottoms. Some sun fading on one as they probably sat in the same spot for 40yrs, lol. Anyway, need to know which one of these is the right LF driver. Pretty certain they're both the same actual unit just from different batches. One must have been replaced along the way buy just curious as to weather the unpainted basket or black basket would be the one that was age appropriate for the serial #s are A 02722 (unpainted) & A 02902 (black). Thoughts?

 

[gpzy]

Unsure if this post is still active, but here goes. I just acquired a pair of AR 10pi’s. The previous owner replaced the woofer with oversized 12 in woofers that don’t fit in enclosed. Bass response is non-existent. Would love to know where to get the proper woofers and mounting bolts. Thanks for any responses in advance.

[lARrybody]

Nice looking Mk1 AR10pi speakers. Those 12 in woofers....Ouch. I would pull them to see if the baffle is still able to accept the truncated AR woofer.  It may take some time but I would start patrolling the auction site for the correct A4 woofers. Even A5 woofers which were used in the Mk2 versions. Those egg crate JBL type foam grills are interesting. You have the makings of some very good 10pi speakers. Tons of information available on this site.  Peace out LarryinIN   

[gpzy]

Unsure if this post is still active, but here goes. I just acquired a pair of AR 10pi’s. The previous owner replaced the woofer with oversized 12 in woofers that don’t fit in enclosed. Bass response is non-existent. Would love to know where to get the proper woofers and mounting bolts. Thanks for any responses in advance.