AR-2ax Tweeters non-functional

[Guest dib]

First post here - apologies if I missed this information somewhere...

I have a pair of AR-2ax speakers that seem to have non-functional tweeters.

The midrange and woofers work properly on both speakers.

Steps taken so far:

I've taken one speaker apart to check the crossovers / pots - No apparent corrosion.

Cleaned both pots with DeOxit Gold. Midrange pots seem to work perfectly on both speakers.

Reassembled pot - reassembled speaker.

Damaged one speaker wire on tweeter (accidentally pulled very thin copper wire from tweeter - ARRGH! Both speakers have dangling wires at present - loosely connected to posts.)

Questions:

How can I test the tweeters to see if they function at all?

How can I repair the wire I've pulled from the tweeter?

Obviously, I am not a novice with Acoustic Research speakers - Please be kind with replies.

Any input is appreciated.

[bitbandit]

First post here - apologies if I missed this information somewhere...

I have a pair of AR-2ax speakers that seem to have non-functional tweeters.

The midrange and woofers work properly on both speakers.

Steps taken so far:

I've taken one speaker apart to check the crossovers / pots - No apparent corrosion.

Cleaned both pots with DeOxit Gold. Midrange pots seem to work perfectly on both speakers.

Reassembled pot - reassembled speaker.

Damaged one speaker wire on tweeter (accidentally pulled very thin copper wire from tweeter - ARRGH! Both speakers have dangling wires at present - loosely connected to posts.)

Questions:

How can I test the tweeters to see if they function at all?

How can I repair the wire I've pulled from the tweeter?

Obviously, I am not a novice with Acoustic Research speakers - Please be kind with replies.

Any input is appreciated.

Hi, and welcome to the forum!

If you get a 1.5v battery and connect one wire from the tweeter to one end of the battery, and briefly touch the other wire to the other end of the battery (easier with an extra piece of wire to make the connection), you will hear a click if the tweeter is working at all.

If that works then you need to look at the wiring and the 6uF capacitor in the crossover. The pots are the usual culprit though - use a multimeter on a low ohm range (up to about 200 ohm) to check they are working properly. Good info in the AR-3a restoration guide which is pinned at the top of the AR discussion forum.

Be aware that the tweeters are aging and a lot of them have reduced output compared to original specs, so it could just be operating very quietly. Try putting a cardboard tube (like from a toilet roll or kitchen roll) over the dome of the tweeter and put your (best!) ear to the other end, and see if you can hear anything. If they are working but low output, then check the 6uF cap too but it might just be old age (the tweeter's, not yours! :-) ) and there isn't a lot to be done about that other than replacement. I have one such tweeter awaiting attention that I will experiment on when I get a chance. I intend to have a go at renewing the suspension and realigning the coil, and I will post results back. There are a few discussions about suitable replacement tweeters if you have a search.

As for the wire - where have you pulled it from? There are tiny wires from the voice coil which join slightly thicker ones (but still thin and fragile) that come out under the tape. If you are lucky and still have the end attached to the voice coil, solder a thin piece of wire to it using a fine soldering iron tip and a steady hand. If you have pulled it out of the voice coil then that is extremely tricky bordering on impossible for the average DIYer. Essentially you would be looking to unwind one loop of the coil and remaking the connection, but you really don't want to have to do that.

Dave

[onplane]

Be aware that the tweeters are aging and a lot of them have reduced output compared to original specs, so it could just be operating very quietly. Try putting a cardboard tube (like from a toilet roll or kitchen roll) over the dome of the tweeter and put your (best!) ear to the other end, and see if you can hear anything. If they are working but low output, then check the 6uF cap too but it might just be old age (the tweeter's, not yours! :-) ) and there isn't a lot to be done about that other than replacement.

Dave

Dave's comment on the aging tweeters is right on!

If that is the situation, it's identical to one a fellow had on Karma. The solution that worked was bi-amping. See:

Waking UP AR Tweeters

If you need help bi-amping, send me a PM (private message) and I'll send you directions.

Regards,

Jerry

[Guest dib]

As for the wire - where have you pulled it from? There are tiny wires from the voice coil which join slightly thicker ones (but still thin and fragile) that come out under the tape. If you are lucky and still have the end attached to the voice coil, solder a thin piece of wire to it using a fine soldering iron tip and a steady hand. If you have pulled it out of the voice coil then that is extremely tricky bordering on impossible for the average DIYer. Essentially you would be looking to unwind one loop of the coil and remaking the connection, but you really don't want to have to do that.

I stupidly pulled one from the voice coil -- *plink* -- I'm courageous enough to approach unwinding some of the loop if you have instructions. It might be a neat learning experience - Although I'll have to approach that project on a day when my hands are steadier than yesterday.

[bitbandit]

I stupidly pulled one from the voice coil -- *plink* -- I'm courageous enough to approach unwinding some of the loop if you have instructions. It might be a neat learning experience - Although I'll have to approach that project on a day when my hands are steadier than yesterday.

Ouch! I assume the 2 tweeters are the same age? In which case, I'd establish whether the one that has both wires intact is working first, and if so how well it is performing before opting for surgery. I haven't had a go at one of the 2AX tweeters yet although as I said earlier, I do have one ready to try when I can get time, but perhaps someone else has had more experience with this tweeter and will chime in?

If you do go ahead you are essentially going to have to try and get under the membrane that forms a dust seal around the voice coil where it joins the dome, without disturbing the 3 spongy blobs that are the suspension for the voice coil. To add to the problems, the spongy stuff will have decayed and is likely to be very brittle rather than compliant, which is in part why the output reduces as they age. IF you can find the stub of the wire that has broken and IF it is in a position where you can solder a wire to it go ahead. Most likely it won't be in a nice convenient place though, in which case you will have to try and un-loop a complete turn of the coil and re route the wire where the original went. There will be small decrease in the resistance of the coil in losing a turn but nothing significant. I can't stress enough that this is not going to be easy and is VERY likely to fail, however, you currently have a useless tweeter, so nothing to lose I suppose.

All in all, not an easy job at all. If you do have a go, I'd appreciate an email of any photos you could take at each step that might help when I get round to doing mine.

Please let us know how you get on. Good luck!

Dave

[Guest dib]

Dave - thanks a bunch for all the info. I will have to check out the tweeter I haven't mangled yet to see if they are worth restoring.

I believe they are 2nd generation tweeters - paper cones, not the 'fried egg' style. I will start budgeting for a replacement set in the meantime -- If I decide to do tweeter surgery, I'll definitely post the results here.

Thanks and Happy Holidays!

[joelongwood]

I believe they are 2nd generation tweeters - paper cones, not the 'fried egg' style.

Interesting................

As far as I know, the AR2ax (both pre and post 1970 versions) only came with the fried egg type tweeters. The earlier generation was a tad larger, though.

[Guest dib]

Interesting................

As far as I know, the AR2ax (both pre and post 1970 versions) only came with the fried egg type tweeters. The earlier generation was a tad larger, though.

Here's a couple pictures - Hopefully, they look okay... I did the battery test with the one that has both leads still connected (2nd photo) and it makes scratchy noises (working)... So I will probably restore the one I mangled (1st photo). One speaker has a serial number sticker on back indicating date of manufacture is 6/74.

[onplane]

Here's a couple pictures - Hopefully, they look okay... I did the battery test with the one that has both leads still connected (2nd photo) and it makes scratchy noises (working)... So I will probably restore the one I mangled (1st photo). One speaker has a serial number sticker on back indicating date of manufacture is 6/74.

I believe you have the new 2ax which has the same woofer and tweeter as the AR-5.

That tweeter in the pic is a 3/4" dome tweeter and similar to the tweeter in the AR-3a. The AR-5 is an 8 ohm speaker and the AR-3a is a 4 ohm speaker. So I believe the tweeter in the 2ax is the 8 ohm version, but I recall reading somewhere that AR only stocked one version of the 3/4" dome.

You should measure the DC resistance of the good tweeter and report it here. That way, we'll all know what tweeter you have (8 ohms or 4 ohms).

Regards,

Jerry

[JKent]

Hi dib and welcome!

I have a couple of pair of the AR2ax's and have learned that those 3 foam blobs tend to give out. They are part of the suspension and not really fixable. Generally speaking, those old tweeters are just wearing out.

Be sure to read the AR3a "bible"--it has lots of info that is relevant to your 2ax's:

http://www.classicspeakerpages.net/library...ring_the_ar-3a/

Also, there are some suitable replacement tweeters. RoyC (an author of the 3a manual) has written in these pages about HiVi tweeters. Search through some of the posts. You could start here:

http://www.classicspeakerpages.net/IP.Boar...297&hl=hivi

Roy may chime in here but I "think" his current favorite is the Q1R. HiVi speakers are available from Madisound and PartsExpress, but I found this site with a lower price:

http://www.soundocity.com/Oregondv/Hi-Vi_R...Q1R_Tweeter.htm

It may be an old site though. I'm told there is no way to actually order from them

Here is what Roy had to say about the Q1R:

The Hi Vi Research Q1R ($23/ea) is my current favorite, and was recently used to replace a pair of original AR-2ax 1" orange dome tweeters. The only crossover modifications were a parallel inductor and a series resistor added to the tweeter circuit, and the results were surprisingly pleasant. The sound is a bit more open and detailed, without compromising the warm character these speakers are known for.

The inductor was an off the shelf 18ga, .05mh air core, and the resistor was 1.5 ohms. The goal was to keep it simple by using the original cap values. The resistor is, in part, used to compensate for the very low circuit impedance caused by the inductor.

I also reversed the polarity of the tweeter connections compared to the original, as the addition of the inductor changes the phase relationship. (AR did this to the AR-11, AR 12, and 10pi when the parallel .105mh inductor was added to the scheme of things.) BTW, the tweeter is mounted sideways because I did not want the new screw holes to interfere with the old cabinet T-nut holes. They are still there, filled with putty, in case an original tweeter faceplate is used again someday.

You may also want to consider replacing the pots with L-pads. They are not "authentic" but they work and don't corrode. PE and Mad have those, too.

Good luck!

Kent

[genek]

I believe you have the new 2ax which has the same woofer and tweeter as the AR-5.

That tweeter in the pic is a 3/4" dome tweeter and similar to the tweeter in the AR-3a. The AR-5 is an 8 ohm speaker and the AR-3a is a 4 ohm speaker. So I believe the tweeter in the 2ax is the 8 ohm version, but I recall reading somewhere that AR only stocked one version of the 3/4" dome.

No, that was the earlier orange-dome AR3/2ax tweeter. The 3/4" came in two flavors, the nom 4 ohm (2.5 ohm DCR) used in the 3a and LST and the nom 8 ohm (5 ohm DCR) used in the 2ax, 5 and LST2. Both look the same, and can only distinguished by P/N if marked, or by DCR if not marked.

[RoyC]

Roy may chime in here but I "think" his current favorite is the Q1R.

Hi Kent,

I'm liking the Q1R more every day. I clearly prefer it over the AB Tech tweeter, regardless of the Q1R's price advantage.

Recently I have been trying it with various inductor and resistor arrangements in the 3a. It is proving to be an easy tweeter to work with, and exhibits no signs of harshness. It is also a near perfect fit in the old tweeter's cabinet hole. (I have found that even the old screw holes can be used.) Attached is a photo of it placed temporarily in a 3a for testing, as well as one in an AR-2ax

BTW, Gene is correct. From about 1970 onward the AR-2ax used the physically identical 8 ohm version of the AR-3a's 4 ohm 3/4" tweeter. It is the same 8 ohm tweeter used in the AR-5 and LST 2. There are many more AR-2ax's out there with the smaller 3/4" dome tweeter than the orange dome "fried egg" tweeter. Incidentally, all of the tweeters' cabinet holes are the same size.

Roy

[frankmarsi]

Roy, Kent, I generally get information late I know, but good gosh I wish some one had told me about these tweeters!

My questions are about their power handling abilities and the coil values to install them in my AR-3a' and AR-LST's. Can these little guys handle much power?

Do either of you fellas care to clue me in, if not any one out there have any other comments to add?

I was planning on stocking-up my tweeter reserve next year and was going to buy from AB-Tech, one of which I've already blown, however seeing the prices of the above mentioned, gee, I rather be purchasing a large number of these ones and not have to worry about my 'stormy' winter nights of loud volume levels and tweeter failure.These guys are cheap enough to replace the next morning when the daylight comes and I can assess the damages.

Santa's friend, FM and a Happy Holiday to All!

frankmarsi@verizon.net

P.S. Maybe not? http://www.avsforum.com/avs-vb/archive/ind...p/t-917499.html

[Carlspeak]

To FM. Check out the link for info on the Hi tweeter. It's 15 W, 30 max. which is about right for the AR application I wouldn't worry too much about that link you provided because most AR applications for the 4 ohm 3/4 inch tweeter had it crossed at 5 kHz.

If you blow a lot of tweeters, you may want to consider putting a fuse in series with them. A ont time effort to do this will save you the hassle of finding replacements in the future or stocking up so many in reserve.

http://www.parts-express.com/pe/showdetl.c...tnumber=297-417

[RoyC]

Roy, Kent, I generally get information late I know, but good gosh I wish some one had told me about these tweeters!

My questions are about their power handling abilities and the coil values to install them in my AR-3a' and AR-LST's. Can these little guys handle much power?

Do either of you fellas care to clue me in, if not any one out there have any other comments to add?

I was planning on stocking-up my tweeter reserve next year and was going to buy from AB-Tech, one of which I've already blown, however seeing the prices of the above mentioned, gee, I rather be purchasing a large number of these ones and not have to worry about my 'stormy' winter nights of loud volume levels and tweeter failure.These guys are cheap enough to replace the next morning when the daylight comes and I can assess the damages.

Santa's friend, FM and a Happy Holiday to All!

frankmarsi@verizon.net

P.S. Maybe not? http://www.avsforum.com/avs-vb/archive/ind...p/t-917499.html

Seasons Greetings, Frank!

You haven't missed much. I've only become serious about the Q1R in the past month or so, after being pleasantly surprised by it in a recent 2ax project. IMO, this tweeter has much going for it as it pertains to our world of ancient ARs. (I see over in Adventland someone has had success with this tweeter as well.)

I agree with Carl regarding power handling. I would add that the use of the NECESSARY parallel inductor with any modern replacement candidate will significantly decrease the chance of damaging it. The old tweeter was not ferro-fluid cooled, and has no such crossover protection. It is therefore much easier to fry. Frank, I believe you mentioned awhile back that you were not using the AB Tech tweeter with the recommended parallel inductor. If not, it is more vulnerable to damage...not to mention the fact that it does not remotely sound like the original without it :-). Yes, a parallel inductor is necessary with the Q1R as well.

As for the various opinions and tests (ie "Zaph") discussed on the internet....Even if those folks are somewhat accurate in their assessments, any faults being discussed rarely apply to our application. We need our tweeter to operate above a rather high 5,000hz. Most of the measurable negative aspects of the tested tweeters occur well below that frequency. There also seems to be a prejudice that the low price of the Hi Vi tweeters equals low quality. After comparing them to various Vifa, Seas, later AR tweeters, and the costly (overpriced) AB Tech tweeter, I have not found this to be the least bit true. They are a bargain, imo. BTW, AB Tech has not had the 3a replacement tweeter in stock for months.

Roy

[frankmarsi]

Fellow AR member Roy C. and others, what would the value of "NECESSARY parallel inductor" for these tweeters? I had bought the required inductors from P.E. for the AB-tech's and they seem to be good.

I'm asking cause if they can handle the power I feed them and be able to sustain, it would make more sense to buy these instead of the AB-tech's, no?

I'm trying to plan for the future and owning the many AR's I do I'd like to be able to pull one from a box as soon as I need one.

Roy, your fotos show a seemingly easy fit, is it?

Thanks for any advice.

FM

[onplane]

I'm asking cause if they can handle the power I feed them and be able to sustain, it would make more sense to buy these instead of the AB-tech's, no?

I'm trying to plan for the future and owning the many AR's I do I'd like to be able to pull one from a box as soon as I need one.

Thanks for any advice.

FM

Hi, Frank!

I'm not the expert on tweeters that Roy is, but I'd say that these new tweeters (fluid cooled) plus parallel coil will handle considerably more power than the stock AR tweeters.

Now, can they handle the power that you send to your speakers is another matter entirely. Frankly, I'm a little perplexed that you are continually "frying" tweeters. Something seems wrong here.

When you are playing music at high levels, Frank, have you ever put the full speaker signal on a scope?

I'm wondering whether the combination of your particular amp, the autotransformer and cap bank have initiated a parasitic oscillation in your amp. I mean, that’s one possible explanation for the “fried” tweeters.

Another explanation is the heavy load on your amp caused by the AR power hungry woofers plus that autotransformer, is causing significant “rail droop”. This, in turn. would result in a high degree of clipping that causes far more than normal demands on your tweeters.

What I’m saying, Frank, is that if you have an incompatibility with your amps, no tweeters may work, regardless of their power capacity.

Regards,

Jerry

[RoyC]

Fellow AR member Roy C. and others, what would the value of "NECESSARY parallel inductor" for these tweeters? I had bought the required inductors from P.E. for the AB-tech's and they seem to be good.

I'm asking cause if they can handle the power I feed them and be able to sustain, it would make more sense to buy these instead of the AB-tech's, no?

I'm trying to plan for the future and owning the many AR's I do I'd like to be able to pull one from a box as soon as I need one.

Roy, your fotos show a seemingly easy fit, is it?

Thanks for any advice.

FM

Frank,

It is a very easy fit, but the Hi Vi tweeters will likely not handle any more power than the AB Tech tweeters. I haven't decided on a preferred inductor value yet.

Check your forum messages, as I don't want to continue to hijack this thread with this topic:-)...

I will try to get some input from other forum members, and create or continue a replacement tweeter thread in the near future.

Roy