AR3a-Improved - newbie questions

[Stephen M]

Hi,

I've just bought a pair of AR3a-improved speakers, and was wondering if I could ask some questions please? 

The main issue is that one of the woofers is not working. I have tested with my multimeter and get a reading around 2.6 ohms. The diaphragm moves in and out when I press it, so there doesn't seem to be an issue there. As a test I swapped in the other woofer, which works, so there isn't an issue with the crossover. Here is a picture of the faulty woofer:

 

This is different to the woofer from the other enclosure, which works. Here is the good woofer:

 

 

I have taken pictures of the midrange drivers as well:

 

 

The tweeters are not original. There is a 2 ohm resistor on the positive terminal lead. Here is the tweeter label:

 

 

And finally, the crossover:

 

 

I'm not at all familiar with these speakers, and was wondering if anybody could offer advice as to whether it would be worthwhile replacing the tweeters and getting the woofer repaired? If the woofer is not able to be fixed a replacement would obviously be needed...

Any advice would be very much appreciated. I'm in Australia, so access to local shops might be difficult.

 

Best Regards

Stephen

[Aadams]

The 3a improved is not the same speaker as the 3a described in the restoration guide.     Your working woofer is a  later version factory replacement from Tonegan.   For tweeters see the thread below on the 3a improved, with content from RoyC.  I don't have a clue on the broken woofer if the lead wires are not broken.

Be patient with the time zone difference.

Adams

 

[DavidR]

The woofer with the 2.6 ohm DCR is the correct reading. If the voice coil was broken it would read OL.

Do you hear any rubbing noise(s) when moving the woofer cone up and down?

[Stephen M]

Thanks Adams and David,

There are no rubbing noises when moving the cone. There is variation in the resistance, between 2.6 and 2.4 ohm over around 10s.

Stephen

[Aadams]

15 minutes ago, Stephen M said:

Thanks Adams and David,

There are no rubbing noises when moving the cone. There is variation in the resistance, between 2.6 and 2.4 ohm over around 10s.

Stephen

Have you tried an Amplifier signal directly on the woofer +\-?

[Stephen M]

Yes, tried this and there's no sound.

[lARrybody]

No break in the lead wires or short in the voice coil. Cone moves freely so no magnet shift. No sound when wired directly(no crossover) to an amplified signal.. This is a real mystery. I would try a second multimeter maybe. Check that the spyder is connected properly. You may have to remove the mesh screens to check this. What does your Tonegen replacement  woofer Ohm out at?  There has to be a explanation.

Edit: Just a thought. Try to re-floe the solder between the lead wire and the speaker terminal strip. Could be a cold solder joint.

[Stephen M]

I've tested it with my main power amp (Anthem MCA 20, see pic below for specs). There is a very faint signal, distorted but at least it's there. I connected the leads to both the terminal tabs and the leads running directly to the cone, and the result was the same. I think I can now discount dry solder in the terminal block.

I've reinstalled the other woofer since testing yesterday, but from memory it was also testing at 2.6 ohms

 

 

 

 

 

 

[RoyC]

Stephen,

2.6 ohms is correct for both woofers.

It is possible the paper voice coil former (common to earlier versions of the woofer) has torn and separated, so the part with the voice coil is detached from the part glued to the cone. Remove the dust cap. If this is the case it will be easy to see. Also check the spider to make sure it hasn't broken free of the cone.

Roy

[lARrybody]

That looks like some pretty nice specs on your power amp. Once you get your AR3a Improved speakers sorted out thay MCA 20 will make them sing. If it was me I would look for another Tonegen 1210003-2A woofer and maybe replace those tweeters with these. HIVI QR1

https://www.parts-express.com/hivi-q1r-1-1-8-textile-dome-tweeter--297-417

Don't know if they ship to Australia or you can find them locally, but there is much information here about how with the right inductor and capacitor they are a very favorable replacement to the original AR 3/4 in dome tweeter.  Good luck on bringing them back online.  

[Stephen M]

2 minutes ago, RoyC said:

Stephen,

2.6 ohms is correct for both woofers.

It is possible the paper voice coil former (common to earlier versions of the woofer) has torn and separated, so the part with the voice coil is detached from the part glued to the cone. Remove the dust cap. If this is the case it will be easy to see. Also check the spider to make sure it hasn't broken free of the cone.

Roy

Thanks Roy. I've never worked on a woofer before so I'll take my time before checking this out.

 

3 minutes ago, lARrybody said:

If it was me I would look for another Tonegen 1210003-2A woofer and maybe replace those tweeters with these. HIVI QR1

https://www.parts-express.com/hivi-q1r-1-1-8-textile-dome-tweeter--297-417

Don't know if they ship to Australia or you can find them locally, but there is much information here about how with the right inductor and capacitor they are a very favorable replacement to the original AR 3/4 in dome tweeter.  Good luck on bringing them back online.  

Thanks for the suggestions, this has saved me a lot of looking around.

[frankmarsi]

The AR 12” woofer has been my favorite for home hi-fi use since 1971-2. Enjoying them with a level of hi-fi passion.

I have been in Hi-Fi love sort of speak since and presently own over 26 of them with 8 of them in use and the rest ear-marked for future systems along with the rest in reserve.

First, do-not hook-up an amplifier as was suggested because that could do damage to the woofer and the amplifier should a shorting accident happen.

I use a partially expired 1.5volt AA battery with leads taped to both pole/sides and then apply that to the woofer’s terminal while observing the cones movement.

I use this same set-up when I do a refoam and I’ve done many of those with-out any problems since 1990.

From my personal experience in dealing with these excellent woofers, it could only be a couple of things.

I have experienced the lead from the terminals that goes into the paper cone that’s is also visible from the front of the cone with a small bead of glue or solder holding it to the paper itself cone might be broken and not attached.

This can intermittently make contact or break contact and one wouldn’t even to be able to see it. That has happened to me and I tried every other conceivable trouble shoot with-out finding what the cause was, it drove me crazy. I only found out by using my fingers to press the cone in and out and that’s when I saw the ‘contact’ point separate. I posted here about it a few years ago.

There’s also a possibility that the tinsel wire lead has separated from the underside of the two point terminal strip mounted to the stamped-steel basket, check that as it can go unseen like the first possibility I mentioned.

Other than these two possibilities there’s only one other instance that I’ve experienced and that’s a break in the copper wire that’s wound around the actual voice coil itself and there’s nothing with-in reason that most folks would do to fix that other than buying a recone kit with voice-coil.

The auction site can be your best friend as it has been for me and this is why I maintain a sizable stockpile of spare raw speakers. I committed to these AR speakers many years ago and have done everything necessary to maintain them.

Good luck and be prepared to frequently check the auction and you may be lucky to find a pair in good condition for a reasonable price.* I purchased most of mine in the early 2000s when prices of $50.-$75. each was the norm. Nowadays, they're going for ridiculous prices.

Also contrary to what’s been mentioned,  your faulty woofer appears to be from the mid or later 1970’s and it's obvious has a newer refoam dust cap indicates these have been refoamed before.

The tweeter shown according to its model number is a “Vifa” tweeter of moderate cost.

FM

* there's one there now, it looks like circa '72

[Stephen M]

Thank you for the information Frank.

31 minutes ago, frankmarsi said:

I have experienced the lead from the terminals that goes into the paper cone that’s is also visible from the front of the cone with a small bead of glue or solder holding it to the paper itself cone might be broken and not attached.

Both this possibility and those mentioned in other posts suggest I would need to remove the dust cap. I have no experience with this - is there a technique you can recommend?

 

31 minutes ago, frankmarsi said:

There’s also a possibility that the tinsel wire lead has separated from the underside of the two point terminal strip mounted to the stamped-steel basket

Does the test I did connecting signal leads to the terminals and then to the tinsel wire lead itself rule this out?

The foam on the inoperative wooder is in very good condition, so it most likely has been refoamed.

31 minutes ago, frankmarsi said:

The tweeter shown according to its model number is a “Vifa” tweeter of moderate cost.

In your opinion, how do these compare, when used in this particular speaker/crossover combination, to the HiVi Q1R 1-1/8" Textile Dome Tweeter mentioned by IARybody previously?

[frankmarsi]

Stephen, removing the dust cap will not give you access to anything other than the magnet shaft/pole-piece and the voice-coil around it, nothing you can fix in there.

It's best to buy a used woofer as I've mentioned. Open a conversation line with the seller before bidding and continue if it appears that you are winning. There were a couple just the other day for $150. for both plus shipping. There's another issue, 'shipping'. On one occasion I've had a disaster and I ended fighting with the seller until he reluctantly accepted them back for a refund. That's why it I always converse with the seller as many don't really have any concept of how the safely ship them. Common sense isn't so common anymore, believe it, it's true!

Question: "Does the test I did connecting signal leads to the terminals and then to the tinsel wire lead itself rule this out?"  FM: no, it's no indication, you'd have to reach your fingers around and behind the terminal block and feel if the those two wires have been broken off or are making only partial contact.

It's obvious it has been reformed by it's age in service. The problem I mentioned with broken leads were the leads were a bit short in manufacture and in my usual fashion of pumping in high wattage to attain 'realistic' volume levels in turn making the cone reach its furthest excursion was how mine broke loose and was at times making contact while other times it did not. That was two weeks of hell trying  to figure it out. I believe RoyC." and I came about the answer here at the same time.

"In your opinion, how do these compare, when used in this particular speaker/crossover combination, compared to the HiVi Q1R 1-1/8" Textile Dome Tweeter mentioned by IARybody previously?"          FM: The "Vifa" line of raw speakers are excellent, if I'm not mistaken, I've heard they no longer sell raw drivers to consumers, only to the trade, I could be wrong though.  I had also looked at the "Vifa" tweeters in that price range before the HiVi Q1R appeared but,  pondering the cost of 16 of them for my 4 LSTs at the time a no-go besides, I don't recall but I think they were either a little too big of too small for the AR hole. The HiVi Q1R is the first useable tweeter that RoyC. tested and proved to be useable in ARs.

Regarding the cross-over configuration, that is something best answered by RoyC. himself as he has the lion's share of all things AR.

Sadly, most of the other knowledgeable veterans have moved-on as the climate has changed here and for other reasons. Luckily, RoyC. is kind, and gracious enough to participate here. 

Do as I suggested, buy two used woofers, install one and store the other as a spare. My stash was put together by the same suggestions that I gave to you. It has become somewhat of a nuisance storing the large number of spare tweeters and woofers that I so joyously attained a number of years ago. I fear that I do come across as a true to life hi-fi freak-a-zoid to anyone who unavoidably sees it. I distract visiting guests by proving why I do what I do as soon as they sit down for a listen. I sometimes have to hold their chins up when they go out my door because of the gapping jaws and mouth after a listening session.

FM

 

[RoyC]

6 hours ago, Stephen M said:

Both this possibility and those mentioned in other posts suggest I would need to remove the dust cap. I have no experience with this - is there a technique you can recommend?

Does the test I did connecting signal leads to the terminals and then to the tinsel wire lead itself rule this out?

The foam on the inoperative wooder is in very good condition, so it most likely has been refoamed.

In your opinion, how do these compare, when used in this particular speaker/crossover combination, to the HiVi Q1R 1-1/8" Textile Dome Tweeter mentioned by IARybody previously?

While I agree with Frank regarding the occasional tinsel lead/cone juncture issue, connecting your meter to the terminals and tinsel lead would not provide a proper (or any) reading if this were the case. The tinsel lead is the connection to the voice coil!

Inspection under the dust cap will often confirm the integrity of the voice coil former in early AR 12 inch woofers exhibiting this type of issue. If the former is torn you will be able to see the damage. Use an Exacto knife to slice around the perimeter of the dust cap and flap it back. It is a simple procedure. If there is no observable damage, simply glue it back down when/if you correct the problem. My recommendations are based on information you have provided stating a steady 2.6 ohm reading at the woofer's terminals, which means the voice coil and associated connections (terminals and tinsel leads) are intact. If this is truly the case, the only way your cone would not move when a signal is applied is if the voice coil is disconnected in some way, or stuck in the gap. Since you have stated that the cone moves in the gap (it should move easily, btw) it isn't stuck, which means the cone has to be separated from the voice coil in some way.

The Vifa tweeter is a good driver, but untested with the 3a or any of its iterations. Even if it was under consideration there would have to be a crossover modification like the one used with the HiVi tweeter to make it sound anything like the original AR tweeter.

Roy

PS Added photo of separated AR 12 inch woofer voice coil former. This woofer is currently on my bench to be rebuilt.

 

[Stephen M]

Thank you Frank and Roy, I'm very grateful for this advice. 

I've removed the dust cap, and it's clear that the voice coil casing has broken down. The copper wire connection seems intact, so this would explain the correct resistance reading at the terminals.

My next question is: should I take to a repair technician, or is this something I could repair?

 

[lARrybody]

Those are some excellent pictures Stephen. That voice coil former is pretty much destroyed. Unless you want to go with a total recone and new voice coil I would look for another woofer.

[Stephen M]

I've has a quick look at replacement woofers, and the price is in the hundreds, plus shipping. Quotes on eBay for shipping to Australia are $200AUD!!!

I'm hoping it's possible to replace the voice coil. I don't know anything about this procedure, but is it possible to replace the voice coil only, or does it require the cone and foam surrounds to be replaced as well? The cone and foam are in excellent condition.

Are there specific kits available for this woofer? I imagine it would be a lot cheaper to ship a kit than the whole driver.

[frankmarsi]

Stephen,  like I mentioned, 'recone' is the last option if cost doesn't permit buying used.

https://www.simplyspeakers.com/acoustic-research-speaker-recone-kit-ar3-ar9-ar11-rk-ar11.html

https://www.google.com/search?source=hp&ei=3qctXu3rDYac5wKeoqnwCA&q=reconing+kits+for+loudspeakers&oq=Recone+Kits&gs_l=psy-ab.1.6.0l2j0i22i30l3j0i22i10i30j0i22i30l4.1480.1480..5825...0.0..0.58.58.1......0....2j1..gws-wiz.C_kKQehrd50

FM

[DavidR]

Keep the original cone and replace the VC

[frankmarsi]

DavidR, that would be one way to go as the AR-3a 12” cone is specially damped and of sufficient weight to give us the renown AR bass phenomenal sound we all lust after if you’re of the type that can discern and appreciate these qualities. However, not being familiar with the newer replacement voice-coil or if, it would lend itself in such fashion of glueing the new VC to the older cone. I’ve handled the newer replacement ‘Tonegen’ briefly and the cone doesn’t seem as damped or as thick and heavy as the original certainly, so much for maintaining originality. Though it’ll work and most can’t discern the difference anyway, I only chose the full replacement with an original vintage and previously used driver as being the most successful.

Unfortunately Stephen is in a spot where shipping charges are introducing difficulty. Stephen would be better off searching the local ads in newspapers or frequenting good-will types of outlets often to acquire one and just getting a ‘parts-donor’ and then refoam it to spec.

It’s gotta be the ‘Three Little Pigs’ scenario all over again. Stephen may be a very nice person and all but, I’m not parting with a single spare driver of mine as I’ve been suggesting acquiring spares since I’ve been on this site going back to 2004.

I only came here originally much like he is and asking if there was a replacement tweeter for my four "LST" and two A-3a speakers and have used all possible alternatives in acquiring a sizable collection since. I've done the same with turntables, tonearms and other soon to be scarce and forgotten items also. These days with six LSTs, two 9s and six 3as, I'm always on the alert even though I have plenty of spare drivers to repopulate each of them. It's what I do as I think of these speakers are for the rest of my days. As it is, I've owned my first 3as for 49 years which is probably more time than the age of half of the members here. Go figure.

It's also what I call 'the Noah's scenario' as I have a major sized stock-pile of midranges, tweeters, and woofers, and amplifiers. How could I not as I've chosen big AR speakers as life-partners in the enjoyment of music, who is more dedicated than me? These speakers are here for my 'forever'.

This is part and parcel of vintage speaker enjoyment and it also typifies any sort of other collection of prized and unique items in this lifetime.

FM

[RoyC]

3 hours ago, DavidR said:

Keep the original cone and replace the VC

Unfortunately, removing the old voice coil is very difficult without destroying the cone, as it was glued to the cone with an epoxy type of glue. I have saved a few cones along the way, but I often use the replacement cone and voice coil seen in the Simply Speakers kit linked above. The kit, however, does not supply an optimal voice coil or dust cap, so the parts are ordered separately from the wholesaler. I also add mass under the dust cap of the new cone to make it respond more like the original. For obvious reasons, I honestly don't recommend an inexperienced individual tackle the rebuild.

Yesterday I rebuilt the woofer with a torn voice coil seen in my earlier post using all replacement parts, including a new cone. This woofer will be available through Ebay's "Vintage AR", who also has all original re-foamed woofers available, many of which I have refurbished. Unfortunately his prices are on the high side, and international shipping adds much to the final tally. Attached is a photo of the rebuild.

As Frank says, "Stephen is in a tough spot" given the shipping cost to Australia.

Roy

 

 

[DavidR]

Lacquer thinner may soften the old glue. If not perhaps toluene but I doubt it.

[Stephen M]

Thanks for all the replies. 

I paid $200 USD for these speakers, so even if I spend another few hundred I will still be ahead I think. Having heard the bass response from the working speaker I would very much like to have the pair up and running.

I have seen the seller "VintageAR" on eBay, so it is good to know your expertise is involved there Roy.

2 hours ago, DavidR said:

Lacquer thinner may soften the old glue. If not perhaps toluene but I doubt it.

I will think about trying this. There is also a speaker repair shop that has been recommended so I will talk to them tomorrow (today is a public holiday in Australia).

3 hours ago, RoyC said:

Unfortunately, removing the old voice coil is very difficult without destroying the cone, as it was glued to the cone with an epoxy type of glue.

At what point does the cone become "destroyed"? The closeup pic below shows a gap between the old voice coil. If I was to be able to keep the cone close to this condition would it still be useable? It seems there is some material upon which the voice coil is glued, between the voice coil connection and the cone material. If I'm able to maintail the radius of this mounting area and fill any small gaps with epoxy when connecting the new voice coil would this work?

I'm considering a painstaking application of toluene to the old voice coil, which would hopefully soak through and reach the old epoxy. After a few hours soaking I would then use an Exacto knife to remove the old material.

 

[RoyC]

2 hours ago, Stephen M said:

At what point does the cone become "destroyed"? The closeup pic below shows a gap between the old voice coil. If I was to be able to keep the cone close to this condition would it still be useable? It seems there is some material upon which the voice coil is glued, between the voice coil connection and the cone material. If I'm able to maintail the radius of this mounting area and fill any small gaps with epoxy when connecting the new voice coil would this work?

I'm considering a painstaking application of toluene to the old voice coil, which would hopefully soak through and reach the old epoxy. After a few hours soaking I would then use an Exacto knife to remove the old material.

There is a very thick layer of adhesive between the outside of the former and the cone. A critical part of the rebuild process is centering the voice coil when gluing it to the cone. The hole must be perfect. You would need to have a better idea of the process to fully grasp the issue.

Toluene and lacquer thinner will not be of any help. You will pass out from toluene fumes long before removing the glue. Take it to the repair shop.

Roy