ar2ax air leaks

[mantis]

Hey guys,

nearly fully restored ar2ax... it has a few airleaks though, as the woofer does not slowly return. It returns almost immediately, and when running an 18hz tone I can hear the woofer make puffs and there is a tiny leak near the midrange driver. Concerning the woofer itself, I have a feeling the problem is near the dustcap. The place I had the woofer refoamed used a black rubber like glue, and I dont think it fully surrounded the dustcap... meaning there could be a big gap somewhere. What should I do about it? Is there some house-hold glue I could use, or should I use some automotive gasket sealant like used on cloth surrounds? Thanks guys.

oh and about the stuffing- I have about 30oz in it, the woofer looks closer to this: http://www.oaktreeent.com/web_photos/Speak..._woofer_web.jpg than this: http://www.antiqueradio.com/images/Oct06-Hayden-Fig4.jpg, so was I right? Or should I remove some of that stuffing?

Thank you.

[AR_nut_in_Oregon]

Hey guys,

nearly fully restored ar2ax... it has a few airleaks though, as the woofer does not slowly return. It returns almost immediately, and when running an 18hz tone I can hear the woofer make puffs and there is a tiny leak near the midrange driver. Concerning the woofer itself, I have a feeling the problem is near the dustcap. The place I had the woofer refoamed used a black rubber like glue, and I dont think it fully surrounded the dustcap... meaning there could be a big gap somewhere. What should I do about it? Is there some house-hold glue I could use, or should I use some automotive gasket sealant like used on cloth surrounds? Thanks guys.

oh and about the stuffing- I have about 30oz in it, the woofer looks closer to this: http://www.oaktreeent.com/web_photos/Speak..._woofer_web.jpg than this: http://www.antiqueradio.com/images/Oct06-Hayden-Fig4.jpg, so was I right? Or should I remove some of that stuffing?

Thank you.

mantis,

30oz of stuffing sounds like it may be too much (almost 2 lbs)...I am in the process of restoring my 2ax's presently and weighed the filling...came out to 27oz (1lb 11oz original from factory). I know them to be original as I was the 2nd owner back in 1972 (purchased from a close friend), and they had never been opened prior to my restoration.

As for the air leak around the mid....if you are using the original foam gasket, I'd get rid of that and resort to the

"putty" mentioned here in many of the posts. Now, on to the woofer....I don't think that the "dustcap" could be the culprit. Again, what was used for sealing the outer frame to the box? Use the "putty"... I would guess that if you are feeling "puffs" around the voice coil, then it could be the spider torn from the cone, or visa versa.

Something I have observed....in replacing the original foam surround woofers with an older cloth surround type, the referbished foams seem very stiff and react very quickly. The cloth are very slow to react, but still will need the Permatex treatment as I can see light through them. The Permatex has worked very well for me on 2 sets of older 4x's....I think they will be around for another 40+ years to come.

Good luck with your project.

[genek]

30oz of stuffing sounds like it may be too much (almost 2 lbs)...I am in the process of restoring my 2ax's presently and weighed the filling...came out to 27oz (1lb 11oz original from factory). I know them to be original as I was the 2nd owner back in 1972 (purchased from a close friend), and they had never been opened prior to my restoration.

The early fabric surround 2's used more stuffing than the later foam surround units (I've heard of as much as 32 oz of stuffing).

My experience has been that woofer seals are all critical, and that the other seals become less critical the farther away from the woofer they are and the more stuffing there is between the woofer and the seal. My latest refurbishment project was a pair of 3a's that had external L-pads mounted on their backs and wires from the old pot connections exiting the cabinets through the original pot mounting holes, no seals at all. Made no difference that I could hear as far as woofer performance was concerned.

If the drivers used foam gaskets, they need to be replaced, at least the ones for the woofer do. These gaskets were never designed to be reused.

[mantis]

hey guys,

I used putty for the woofer sealer, and the other drivers as well to be sure. I am not sure If I am feeling air around the woofer, it is hard to tell, but I can hear all sorts of things when I crank it and put 18hz on it. I have 3as as well, and even though they were re-foamed they are very very slow to return to position... talking 3 seconds or so. So whats going on with this 2ax? Is it supposed to be like that becuase the woofer is just smaller? Its not much smaller... hm.

[genek]

hey guys,

I used putty for the woofer sealer, and the other drivers as well to be sure. I am not sure If I am feeling air around the woofer, it is hard to tell, but I can hear all sorts of things when I crank it and put 18hz on it. I have 3as as well, and even though they were re-foamed they are very very slow to return to position... talking 3 seconds or so. So whats going on with this 2ax? Is it supposed to be like that becuase the woofer is just smaller? Its not much smaller... hm.

My 1975 2ax's (foam surrounds) take about two seconds to return. Their low end response is only rated to a bit above 40 Hz, so I have no idea what if anything you ought to be hearing when you feed them 18 Hz.

[mantis]

My 1975 2ax's (foam surrounds) take about two seconds to return. Their low end response is only rated to a bit above 40 Hz, so I have no idea what if anything you ought to be hearing when you feed them 18 Hz.

i hear mechanical noises rather than a tone, I think, I have to give the speakers "loud" volume knob placement to get the woofer really moving. Should I be testing with a different tone for air leaks? And that slow return, I dont know why it is so quick... hear me out here and tell me if this makes sense- if I overstuffed them, and the seal is in fact damn good, then a test for this would be to hold it in for a while (like 10 sec or so) then release and see if its slower then? Otherwise, it can't be overstuffing causing this right?

[johnieo]

Otherwise, it can't be overstuffing causing this right?

Hello:

Stuffing should only affect the values for finished cabinet resonant frequency Fc, and cabinet damping factor Qc. When I restored two AR-2ax given to me, a couple of years ago, I found 26.7 oz of fiberglass in one cabinet, call it "A," and 32 oz in "B."

After removing the woofers I measured their free air resonances and found both drivers to be Fs = 27 Hz. However their Qs values differed. Qs(A) = .55 and Qs( B ) = .60 (measured in open air)

Then I restuffed them with equal values of fiberglass -- 30 oz. Then measured their overall cabinet Q and found the values were different. Qc(A) = .61 and Qc( B ) = .74

So I thought maybe AR set the stuffing weights differently on purpose. So I put 32 oz in "A," and 25 oz in B. These were the weights on receipt, and then measured Fc = 52 Hz and Qc = .66 for both cabinets. In both cases, the cloth surrounds were in excellent condition; a tiny dab of very dilute Permatex was used to cover a small thin spot on one driver.

I wondered if AR had developed some simple algorithm whereby they would lighten up on the stuffing if the driver's open air Qc was low, and increase it a bit if it was high. I have no idea how much detailed fussing AR did during manufacture of speakers of that generation, so the original stuffing weights and measured final (equal) Qc values may have been simply serendipitous.

Cheers,

[johnieo]

i hear mechanical noises rather than a tone, I think, I have to give the speakers "loud" volume knob placement to get the woofer really moving. Should I be testing with a different tone for air leaks?

Villchur's concept of using an 18 Hz waveform tp detect leaks required use of a stethoscope to locate the leaking air puffs. It goes without saying that if he needed a stethoscope, he could not pinpoint the sound with his unaided ear, and neither could we. Thus rock music levels would not be needed.

[kkantor]

Not serendipitous, but more like a weak feedback loop: "Hey, a lot of speakers are failing QC. What should we do about it?"

-k

Hello:

Stuffing should only affect the values for finished cabinet resonant frequency Fc, and cabinet damping factor Qc. When I restored two AR-2ax given to me, a couple of years ago, I found 26.7 oz of fiberglass in one cabinet, call it "A," and 32 oz in "B."

After removing the woofers I measured their free air resonances and found both drivers to be Fs = 27 Hz. However their Qs values differed. Qs(A) = .55 and Qs( B ) = .60 (measured in open air)

Then I restuffed them with equal values of fiberglass -- 30 oz. Then measured their overall cabinet Q and found the values were different. Qc(A) = .61 and Qc( B ) = .74

So I thought maybe AR set the stuffing weights differently on purpose. So I put 32 oz in "A," and 25 oz in B. These were the weights on receipt, and then measured Fc = 52 Hz and Qc = .66 for both cabinets. In both cases, the cloth surrounds were in excellent condition; a tiny dab of very dilute Permatex was used to cover a small thin spot on one driver.

I wondered if AR had developed some simple algorithm whereby they would lighten up on the stuffing if the driver's open air Qc was low, and increase it a bit if it was high. I have no idea how much detailed fussing AR did during manufacture of speakers of that generation, so the original stuffing weights and measured final (equal) Qc values may have been simply serendipitous.

Cheers,