Acoustic Suspension Seal Video

[jnolan5784]

 

 

Two videos to demonstrate the acoustic suspension seal. I had the tweeters out of my early AR-3a's for rebuild, so I thought it would be a good demonstration of what a seal should look like. The first video does not have the tweeter installed therefore there is no seal. The second video is after installation of the tweeter with a properly sealed cabinet. 

 

 

 

 

[AR surround]

I'm seeing a "play" bar, but no videos.   Anyone else having problems?

[DavidR]

same here

[JKent]

Worked for me. Good demo (but I'd still use Roy's goo)

[jnolan5784]

Thanks, I have some of Roy's sealant, but Roy himself said that 12 AR inch woofers rarely needed it, so I didn't apply it. Anyone have any other thoughts or experience on the cloth surround 12 in woofers of 3's or early 3a's?

 

[JKent]

Those do pass the push test but the sealant looks kind of dried up and flaky to me. I re-sealed my own AR-3 woofers. I remember the KLH Service Bulletin in our library that told service centers to always re-dope (KLH) cloth surrounds regardless of the reason for service.

Kent

[jnolan5784]

Where do you apply the sealant?

[JKent]

Using a small brush, apply a thin coat to the entire cloth surround and the dust cap. Here's a link to the KLH instructions. KLH called the cloth surround a skiver

http://www.classicspeakerpages.net/library/klh/other/klh_schematicsservice/klh_service_bulletin_60.pdf

 

Edited November 23, 2022 by JKent
Removed pictures

[RoyC]

On 7/13/2022 at 7:25 AM, jnolan5784 said:

Thanks, I have some of Roy's sealant, but Roy himself said that 12 AR inch woofers rarely needed it, so I didn't apply it. Anyone have any other thoughts or experience on the cloth surround 12 in woofers of 3's or early 3a's?

 

The AR woofer's surround always looks like that, and is different than the KLH surround. The original sealant does not flake off or disappear from either of them. Many KLH woofers were simply insufficiently treated at time of manufacture, prompting the KLH technical service bulletin recommending additional sealant. AR woofers were usually pretty well treated at the time of manufacture, especially the 12 inch AR woofer. Accordingly, my sealant is is deliberately thin and intended to only be supplemental to the original treatment.

When my sealant is used on cloth surrounds of AR woofers, I recommend a very light application. The toluene in the sealant softens the original sealant, which may be somewhat beneficial, but if it is applied too heavily it can collapse the roll of the AR canvas-like material. For this reason I don't recommend using it at all if an AR woofer passes the "push test". On the other hand, the inverted cloth roll of KLH woofers is made of a different (more porous) material and is not prone to this potential issue. KLH woofers almost always require a couple of additional applications.

Roy

[JKent]

Thanks Roy. Learn something new every day! So jnolan was right. I was not aware of the difference between AR and KLH cloth surrounds.

Kent

[RoyC]

5 hours ago, JKent said:

Thanks Roy. Learn something new every day! So jnolan was right. I was not aware of the difference between AR and KLH cloth surrounds.

Kent

Hey Kent,

I learned some of this along the way as well. I suspect the KLH material was too soft to be made into a roll, making the inverted installation necessary.

Roy

[zcon67]

Hi Roy and Kent,

Back to working on the AR-3's after a long time after having to attend other things.  Now to work on the important stuff, speakers.  I have reassembled them and found them very bright with little low end.  Reinstalled stuffing with 28oz instead of 24oz and the push test was good.  I have resisted messing the surrounds after reviewing tons of posts still reluctant to try anything before checking with the experts.  I treated some KLH5's with your goop, Roy, that much improved them.  Thanks to Kent and his very helpful posts and advice.  I sold them and having regrets already.  Is it possible these surrounds have stiffened so much that it prohibits movement?  I thought I might lightly clean them with a solvent and apply the sealer but thought I would check further.  I appreciate all thoughts.

Pete

[RoyC]

5 minutes ago, zcon67 said:

Hi Roy and Kent,

Back to working on the AR-3's after a long time after having to attend other things.  Now to work on the important stuff, speakers.  I have reassembled them and found them very bright with little low end.  Reinstalled stuffing with 28oz instead of 24oz and the push test was good.  I have resisted messing the surrounds after reviewing tons of posts still reluctant to try anything before checking with the experts.  I treated some KLH5's with your goop, Roy, that much improved them.  Thanks to Kent and his very helpful posts and advice.  I sold them and having regrets already.  Is it possible these surrounds have stiffened so much that it prohibits movement?  I thought I might lightly clean them with a solvent and apply the sealer but thought I would check further.  I appreciate all thoughts.

Pete

Hi Pete,

If nothing has been applied after they were manufactured, AR surrounds really don't stiffen much on their own. I have, however, seen many woofer surrounds compromised by the application of inappropriate materials at a later time. Adding some of my stuff won't hurt anything, but there is no way of knowing how much it will improve the response.

You could try reducing the mids' level control/pot settings and turning up the overall volume of your amp...

Roy

[zcon67]

Hi Roy,

Good to see your voice again.  I have reduced the mid but just sounds muffled, mids mostly coming from the woofer.  These mids are the one's you sent long past.  Since that time you have been working on the old ones so I might should send them to you along with the tweets to see if they can be put to use again.  Thats not going to help the woofer problem though.  Surrounds don't appear to have tons of extra sealant so maybe there are other factors.

Pete

[JKent]

Little low end. Any chance they’re out of phase? I’d try reversing the speaker wires on one just to check. 

[zcon67]

Hi Kent,

I use 16 zipcord that has a key on one side but I might check on the speaker selector I use to make certain that is correct.  That gets to be tangled mess, so back to the tangled mess.  Good thought.

Pete

[RoyC]

2 hours ago, JKent said:

Little low end. Any chance they’re out of phase? I’d try reversing the speaker wires on one just to check. 

Great suggestion!