AR-3 woofer

[ninohernes]

My woofers are making a strange sound. Ever since I replaced the crossovers in these speakers, the woofer, during strong bass passages has made a sound much like a woodpecker, a clicking sound. What is this? Is there anything that can be done to stop this sound? It’s quite distracting when listening, and the woofers have never done this before.

[Guest dogmeninreno]

>My woofers are making a strange sound. Ever since I replaced

>the crossovers in these speakers, the woofer, during strong

>bass passages has made a sound much like a woodpecker, a

>clicking sound. What is this? Is there anything that can be

>done to stop this sound? It’s quite distracting when

>listening, and the woofers have never done this before.

Well, while I am not an expert, I would first replace the cap in the woofer circuit. Stand by because i think you will get lots of suggestions from the forum!! Dale in Reno.....Are you sure that the woofers are ok?

[Guest Nigel]

Dale;

I don't believe that the AR3 has any caps in the woofer's signal path.

To me it sounds like the drivers might have been subject to poor quality refoaming job that did not get them properly aligned. This is jsut a guess.

Are the wookers original? Have they been refoamed? Did they get plugged into 120VAC 60Hz? It is pretty hard to damage an AR 12" woofer.

Nigel

[tysontom]

>My woofers are making a strange sound. Ever since I replaced

>the crossovers in these speakers, the woofer, during strong

>bass passages has made a sound much like a woodpecker, a

>clicking sound. What is this? Is there anything that can be

>done to stop this sound? It’s quite distracting when

>listening, and the woofers have never done this before.

In what way did you change the crossover? Did you change values or crossover point? Are there ferrite-core or air-core chokes in the new crossover? Are the woofers the original aluminum-frame, Alnico versions or have your AR-3's been retrofitted with the newer-style ferrite woofer? Until you said you changed the crossover, I thought I knew the problem.

--Tom Tyson

[ninohernes]

The woofers are the original alnico magnet woofers. I built a new crossovers using Layne Audio's schematics, in other words, I built them to original spec. The woofers have not had new surrounds put on them, although I did coat them in Layne Audio's cloth surround sealer, but I did that long before I replaced the crossovers. The noise it is making sounds mechanical not electrical, like metal on metal.

[Steve F]

It sounds as if your woofers are "bottoming," that is, the voice coil former is striking the backplate during long excursions. It is indeed a mechanical sound, and you may damage your speakers if you continue to play them at high levels.

It could be that either the surround or the spider is not providing the proper amount of damping/restoring that they should. I know you said you've resealed the surrounds, but what condition are the spiders in? They will deteriorate with age, and your AR-3's are over 40 at this point.

It could also be a slight misalignment of the voice coil in the gap. At the top of the gap, with little excursion, everything is clear. But with longer excursions, the misalignment becomes apparrent and the voice coil strikes the side of the gap. This would be more of a rubbing or scraping sound than the sharp 'thwack' of voice coil bottoming.

Steve F.

[ninohernes]

How much would it cost to have the surrounds replaced? And this may sound stupid, but what is the spider?

[tysontom]

>The woofers are the original alnico magnet woofers. I built

>a new crossovers using Layne Audio's schematics, in other

>words, I built them to original spec. The woofers have not

>had new surrounds put on them, although I did coat them in

>Layne Audio's cloth surround sealer, but I did that long

>before I replaced the crossovers. The noise it is making

>sounds mechanical not electrical, like metal on metal.

The Alnico woofers are rugged, and actually do not "bottom" per se, since the back plate is about two inches behind the bottom of the voice coil. The moving assembly does come to a stop on other parts, however, after about 1/2-inch to 5/8-inch depression off mid-center. The cone can actually move back and forth up to about one inch, but not in a linear fashion. Linear travel is a little over 1/2-inch, peak-to-peak.

What I have encountered in some cases is that the glue that holds the masonite rings on both the spider and the surround gets brittle, and can separate, allowing the masonite parts to loosen and slap against the metal speaker frame. You usually don't notice anything until the woofer is driven fairly hard, and then you hear clicking noises and distorted sound. What you have to do is check first the outer surround, where the masonite is fastened to the frame, and see if it has separated; then pull the woofer and check the inner masonite ring to see if it has separated. You can check the woofer to make sure the voice coil is not rubbing, too. Three fingers around the dust cap, gently push the woofer in and out.

Incidentally, one of the best treatments for the cloth surround is to put several coats of Armor All Protectant (used on automobile tires and interiors) on the surround. This usually softens and seals the old cloth surrounds up a bit, and is better than putting another material on the cloth. Originally, AR used a butyl-rubber compound on the cloth surrounds which was a mineral-base substance; later, I think they used a water-based butyl-rubber (similar to Lord BL-100 or Airflex 400) with the ferrite woofers with urethane-foam surrounds. This material dried clear, or in some cases it was mixed with lamp black to make it dry black.

--Tom Tyson

[ninohernes]

I have checked where the surround attaches to the frame, the masonite rings have come up a bit just in one spot. I glued them down so that they don’t move anymore. This still has not solved the problem. The spider looks ok and isn’t coming up. This is an interesting problem, but I think having the surrounds replaced will solve the problem. I think the cone may be slightly off center, when having the surrounds replaced, you have to re align the cone, don’t you? I’m not very knowledgeable when it comes to woofers.

[tysontom]

Well, there is another possiblity: the point at which the voice coil attaches to the cone. The coil is wound on a bronze bobbin, with many small holes around the top, just under the dust cap, to allow glue to attach to it. I am not referring to the larger holes to let air escape from within the pole piece during large excursions. I have seen a couple woofers where this bond was slightly broken, causing the woofer to make noises. You will have to carefully remove the dust cap (you will want to glue the original back in place when complete) and look at the voice coil where it connects to the cone. Also check the pigtail wires to be sure they are not binding under long excursions -- this is another potential problem area.

Does the surround make any noise when you push the woofer in and out when it is out of the cabinet? Sometimne a hardened cloth surround will wrinkle and make noises, but it would not likely be a clicking noise.

--Tom Tyson

[tysontom]

Incidentally, the reason this glue comes undone at the voice coil can be due to excessive excursions, causing the cone to reach the end of its travel. This is not bottoming against the back plate -- that's two inches further back -- but the cone where it attaches to the coil and skiver can come in contact with the "top" plate of the magnet structure, and the glue can be knocked loose if the woofer hits this area hard enough. Check for air leaks, etc., in the cabinet that may be letting the woofer make over-large sub-sonic excursions. The cabinet is not intended to be hermetically sealed, but reasonably air-tight in an acoustical seal.

--Tom Tyson

[ninohernes]

I think I want to have the surrounds replaced on my woofers, just so I wont have to worry about them. I also want to have them the woofers looked at in depth to make sure that the spider and all of that stuff Tom talked about is ok, and if its not, have it repaired. Who does this stuff besides Layne Audio? I would send them to Layne Audio but they are impossible to get a hold of, and it would probably take forever to get the work done. Do any of you guys do this stuff, and if you do, how much would it cost?

[ar_pro]

Try Bill Miller at:

Millersound Labs, 1422 Taylor Road, Lansdale, PA 19446, Phone 215-412-7700 Fax 215-412-0542

He's repaired a total of twelve AR-9 woofers for myself and family, as well as many other AR speakers.

[tysontom]

If you will carefully remove the dust cap, you can check the voice-coil-to-cone union yourself. You have gone this far, and I assume that you have removed the woofer from the cabinet, why not see if that is not the problem? If the voice coil has begun to separate from the cone, you can carefully epoxy the assembly back together. I have done this before, and it is tedious -- especially to be sure that epoxy doesn't get down into the gap area. It just takes patience, but it is well worth it. There are only so many things that can go wrong, and you have eliminated most of them. You may not need to replace the surround unless it is badly dried-out or dry-rotted or something, and is leaking air badly.

This problem is not a common one with the AR-3 woofer, but considering its age, the glue is getting brittle in some cases. Did you notice this problem immediately after you retrofitted the crossover, or sometime after that?

--Tom Tyson

[ninohernes]

I noticed it immediately after.

[fedeleluigi]

>I noticed it immediately after.

why don't you try the old crossovers to verify if the problem depends on the new ones. Is it very strange that the problem appeared in both woofers simultaneously.

Luigi

[ninohernes]

The old crossovers no longer exist, I discarded the old parts. Oh I did notice that the spider on one of them has indeed come lose, I re glued it but it still makes the noise.

[tysontom]

>>I noticed it immediately after.

>

>why don't you try the old crossovers to verify if the

>problem depends on the new ones. Is it very strange that the

>problem appeared in the two woofers simultaneously.

>

>Luigi

Well, I just realized that you said that "both" woofers are clicking. I should have read more carefully the first time around. The likelihood of both woofers having the same mechanical problem is remote at best. It now would definitely seem to be something in the new crossover, a leaking capacitor or something in the tweeter circuit, but I really don't know what could cause it since there is only a choke in the woofer circuit. Are your AR-3 serial numbers above #1414 and below #19468? There were some minor changes to the crossover, but I don't see how it could cause your clicking problem. Try disconnecting the woofer from the tweeters (unhook the strap between T and 2), and see if you still get the clicking.

--Tom Tyson

[ninohernes]

Yes, I do still get the clicking, Im positive it’s a mechanical problem, not an electrical one. The noise only occurs when the system is playing fairly loud and during copious bass passages, such as a timpani hit, or a low note during a double bass solo. The driver is sealed in the cabinet almost airtight, so the woofer can’t be making any subsonic excursions. (Airtight meaning its quite difficult to push the woofer in with your hand.)

[tysontom]

>Yes, I do still get the clicking, Im positive it’s a

>mechanical problem, not an electrical one. The noise only

>occurs when the system is playing fairly loud and during

>copious bass passages, such as a timpani hit, or a low note

>during a double bass solo. The driver is sealed in the

>cabinet almost airtight, so the woofer can’t be making any

>subsonic excursions. (Airtight meaning its quite difficult

>to push the woofer in with your hand.)

Well, I'm about tapped out on this one. How much power is going into the speakers? What is the make and output-power of your amplifier? Are you using a bass equilizer, such as the Allison ESW? When you look at the woofer during the loud passages, can you visualize how large the excursion is? Put a white "dot" on the cone and watch it during those loud passages; if it is moving much greater than 1/2-to 3/4-inch, peak-to-peak, then you might be causing the lead-wire pigtails to bind and make noise (this can make a clicking noise); the bottom of the cone where it joins the voice coil might also be touching the top pole-piece under great excursions, as mentioned before, but the speaker has to be driven very hard to get to this point. You did not answer the questions in my previous message about serial numbers. Did the vendor who sold you the new crossover ask this question regarding serial numbers, when you ordered your new crossovers? There were slight differences in the crossover after those serial numbers I mentioned, but I doubt that it would have any effect on the woofers.

Remember, too, that "electrical" problems can be manifested in "mechanical" sounds, such that an electrical problem will be reproduced through the speakers, making you think the woofer is experiencing mechanical problems. They are, after all, accurate sound reproducers.

Last resort would be to remove the woofers from the cabinet and connect them to a signal generator or sine-wave generator and drive the woofer in free air at low frequencies to see if it makes the clicking noises you hear.

--Tom Tyson

[Guest Barrydor]

>Last resort would be to remove the woofers from the cabinet

>and connect them to a signal generator or sine-wave

>generator and drive the woofer in free air at low

>frequencies to see if it makes the clicking noises you hear.

When had my woofers refoamed, the place that did the work used this technique to check the voice coil centering. Set the sine wave generator to 0.5 Hz or less and slowly bring up the amplitude. The speaker will move slowly back and forth through it's excursion and you will hear any mechanical noise that occurs.

Also, the terminal board on AR woofers is held in place with a single rivet. On some woofers, I have noticed it has a tendency to rock back and forth from it's normal position. If this happens, it could pull one of the pigtail wires tighter than the other.

You might want to check and be sure that the terminal board has not rocked to one side or the other. If this happens, I center the terminal board and place a drop of epoxy between the terminal board and the speaker basket to keep it in place before I reinstall the woofer.

Barry

[ninohernes]

Tom, The serial numbers are C 36202 and C 30483, and I used this crossover and these components, except I left out the mid coil because my mid driver has the pad over it. My amp is 75 watts per channel into 4 ohms. It has a Fletcher Munson (loudness) switch. http://layneaudio.hypermart.net/images/AR3xo.jpg

[roundhome]

Hello I just got on but have been following you work. i had a speaker that made a noise like a wood pecker when you turned it up. It turned out to be a lose cap taping on the back of the driver i found it buy putting a screw driver to the back of the speaker and listening to the handle. Just a idea. good luck. I just did a upgrade on my Ar3s and the sound great can't wait to put some real power to them.