2 replies to this topic

[ed1]

I have 2 AR-LST's - serial #797 and #800 purchased used in 1974 or so. I have used them on and off - mostly off - ever since. I have recently upgraded my home theater equipment and would very much like to continue using these speakers.

One of the LST's (#797) produces an unclear, buzzing sort of sound from the woofer. I opened the grille area and saw that the woofer is in serious need of refoaming. So, I am considering doing that myself as I am somewhat handy but have never worked on a speaker before. I read the Library guide to refurbishing the AR3 as well as additional refoaming guides. The surrounds on both #797 and #800 are cracked and need to be replaced, but only #797 is buzzing.

Before I decide whether to jump in to this project, I am trying to determine whether all drivers are working. They all produce sound and the mid-ranges on both LST's seem OK. The tweeters on #800 are OK, I think. But I can only barely hear any sound from the tweeters on #797. I am only using my ears, so far, for this determination.

So, my initial questions are these:

1. Will fixing the woofer surround on #797 eliminate the scratchy, buzzing sound? Or could it be caused by other things?

2. As I believe these LST's are relatively early in AR's manufacture of LST's, should I be replacing the capacitors and other parts as well?

3. How can I better test whether the tweeters are working properly? Are there test CD's with high frequency sound for this purpose?

Of course, I will try to get a cost estimate together for a self-repair once I can reasonably figure out what to do. I have seen some vendors offering replacement or refurbished original woofers and drivers for the LST, so that will be the alternative I suppose.

Thank you for any advice. I really need it.

P.S.-I also have a couple of barely ever used Allison 8's (rare bookshelf model in oak, purchased new around 1985) that I will get to next!

[dynaco_dan]

I have 2 AR-LST's - serial #797 and #800 purchased used in 1974 or so. I have used them on and off - mostly off - ever since. I have recently upgraded my home theater equipment and would very much like to continue using these speakers.

One of the LST's (#797) produces an unclear, buzzing sort of sound from the woofer. I opened the grille area and saw that the woofer is in serious need of refoaming.


COMMENT: The surround needs to be replaced correctly to re-center the voice coil/magnet again. Both surrounds need to be replaced together.


So, I am considering doing that myself as I am somewhat handy but have never worked on a speaker before. I read the Library guide to refurbishing the AR3 as well as additional refoaming guides.


COMMENT: I purchased 2 kits and did my own during the mid 90's. My first one took me 1 1/2 hours and the second about 10 minutes. With the AR manual and a lot of care and patience you can do the task.

The surrounds on both #797 and #800 are cracked and need to be replaced, but only #797 is buzzing.

Before I decide whether to jump in to this project, I am trying to determine whether all drivers are working. They all produce sound and the mid-ranges on both LST's seem OK. The tweeters on #800 are OK, I think. But I can only barely hear any sound from the tweeters on #797. I am only using my ears, so far, for this determination.


COMMENT: Check out the fuses, the speaker will have much reduced output even with a blown fuse inline.


So, my initial questions are these:

1. Will fixing the woofer surround on #797 eliminate the scratchy, buzzing sound? Or could it be caused by other things?

2. As I believe these LST's are relatively early in AR's manufacture of LST's, should I be replacing the capacitors and other parts as well?


COMMENT: Don't start replacing anything else just yet.


3. How can I better test whether the tweeters are working properly? Are there test CD's with high frequency sound for this purpose?

Of course, I will try to get a cost estimate together for a self-repair once I can reasonably figure out what to do. I have seen some vendors offering replacement or refurbished original woofers and drivers for the LST, so that will be the alternative I suppose.

Thank you for any advice. I really need it.

P.S.-I also have a couple of barely ever used Allison 8's (rare bookshelf model in oak, purchased new around 1985) that I will get to next!

[ar_pro]

There are a number of websites that offer test tones for download - here's one: http://mdf1.tripod.com/test-tones.html

But go easy on your tweeters with HF sine waves!