Jump to content

AR 11 Restoration


Guest special rider

Recommended Posts

Guest special rider

Hello-

Just got a pair of AR11s from craigslist. I had a pair when I was younger- bought them from the AFES catalog when I was in the service. I remember that they were extremly power hungry. The cabinets look pretty good on this pair, I know that I will have to replace the foam on the woofers. I am not sure what else I will have to do to use these in my living room.

I would love to find the stands that are shown in the brochure.

I have a sweet pair of KLH six in my family room- I love that "olde school" acoustic suspension sound.

I had thought about powering the ARs using my HK PA 2100 & Parasound HCA 600 in bridged mono- niether amp is recommended for <8 ohms in bridged configuation- Any feed back from users of this fourm?

Both amps are about 65w channel into 8 ohms, the HCA is 75w into 4 ohms.

I will need to replace the grill foam on the 11s- any advice?

Thanks- Keep on Truckin !

Link to comment
Share on other sites

Special Rider:

Will try again, first attempt to post failed. Perhaps Rich Laski will respond -- he has much experience with these speakers.

Two comments: First, ar_pro is correct; you will need amps capable of driving a 4-Ohm load. 75-100 W minimum per channel, 250-350 W is desirable.

Second: Although the metal stands and crossed-arm walnut stands may look elegant, they elevate the woofer too much from the floor. I experimented with 0-, 4- and 8-inch elevations and decided that 4-inch was maximum elevation for a tile floor. They can sit on a carpeted floor and sound fine. My speakers are set 5-6 ft. apart in the center of a wall and with backs within a couple of inches of the wall.

Before you focus on the appearance of the mounting stands, you might experiment with phone books and observe how the bass response decreases with elevation.

Cheers,

Link to comment
Share on other sites

  • 2 weeks later...
Guest special rider

Hello All-

I wanted to post an update on my AR11 restoreation-

I have refoamed the woofer surrounds, cleaned and polished the cabinets and hooked them up in my family room.

They sound GREAT.

I positioned & powered them the way my KLH Sixes were set up.

The KLHs had been elevated about 8 inches, I raised the ARs to about 13 inches. I think that they sound better at this hieght and I am looking for a way to get them to about 16-18 inches.

I am disapointed that the foam grills are not available- these came with some brown replacemnt foam that I think the Shack used to sell.

If anyone has a source or DIY solution please let me know.

I did get fuses and I am looking for the fuse holders.

Can you hear when capacitors need replacement? If so how would this condition "Sound"?

As I said in annoter post when I place my ear close to the tweeters in either speaker it sounds "Shaggy".

I have gotten lots of good information from CSP and have enjoyed the forums.

Thanks, Wayne - Keep on Truckin!

Link to comment
Share on other sites

Wayne:

I too realized that replacement foam was not available, and if so would only last 15 years. Wood picture frames were fabricated from a strip of wood approx. 1/2-in wide by 3/4-in deep, then the outer side was beveled on the long edge to match the bevel of the original foam. These were mitred into the shape of a picture frame with a cross brace between the woofer and midrange. After painting them black, I stretched black grille cloth --the kind that is elastic and easily stretched -- around the frame and stapled in on its backside. These I mounted with Velcro. From a distance one cannot tell they are not foam, and most importantly for me they have the same form factor as the original.

Seriously, you should try your speakers elevated no more than 4 inches from the floor, or less. You will find their base response excellent in this position. Should you be concerned that the tweeter radiates too low, then angle the tops of the base units by 7 degrees. The old AR stands may have looked elegant, but .......

Cheers,

Link to comment
Share on other sites

Guest special rider

Thanks John-

The picture frame molding sounds like a good idea and could look quite nice. Thanks for the idea.

I am playing with the hieght & placement of the 11s, I will try your suggestion of 4 inches or less- If I do do find that the lower hieght is what I want that makes finding/making speaker stands much easier- I have seen many off the shelf items that would work.

What electronics are you using with your 11s?

Do you have other ARs ?

Wayne

Link to comment
Share on other sites

Guest Bret

Wayne - as John told you, Rich Laski is the local AR-11 restoration expert, but as he seems to be AWOL I'm going to give the capacitor issue a shot.

Your speakers probably have either Sprague Compulytic or Callins non-polar electrolytic capacitors in them. Either brand seems to be more prone to failure than the capacitors in much older or much newer speakers.

John O'Hanlon has provided us with thorough testing of old capacitors and dazzling explanations for why this type of capacitor fails over time. The reasons are interesting, you might want to search the forum for the capacitor threads and give them a read.

It's almost a given that at least some of your capacitors are bad. There will be almost no dissent that you should replace them all. If you ask "With what, exactly?" there will be a collective "Aaaarrrrgh!" from forum members since this is an argument with no end.

You should replace them with high-quality "like-kind" capacitors. If you find any, let us know. Otherwise you will have to compromise. At least a few forum contributors suggest using polypropylene replacement capacitors. Most of those who use poly capacitors would suggest that you "add-back" lost resistance equal to the original electrolytic capacitors. Nobody is exactly sure how much that was, originally, but one contributor recently made a reasonable-sounding suggestion.

"I suggest a .33 to .47 ohm resistor in series with film caps generally, if the ESR is not known. I suggest .47 for this application. Either value is far better than zero."

Probably your cheapest / safest bet is to use new non-polar eletrolytics. If you go that route you might want to "google" "by-pass capacitor" and see if that theory appeals to you for the tweeter capacitor. It appeals to me, but others aren't so easily duped.

The "shag" you hear in the tweeters is probably caused by failing capacitors. But it isn't the capacitor's "shag" you hear. The tweeter itself is "shagging" as it is beating itself to death. The bad capacitor is allowing frequencies to pass which are too low for the tweeters to tolerate. I'd quit playing them until you fix that one way or the other.

Make sense?

Bret

Link to comment
Share on other sites

>> Rich Laski is the local AR-11 restoration expert, but as he seems to be AWOL I'm going to give the capacitor issue a shot.<<

Thanks for the compliment. Sorry for not responding. I’m neck deep in a major DIY remodel of my home – no time for audio until I put the house back together.

Wayne,

>>I am not sure what else I will have to do to use these in my living room. <<

I’ve posted information and pictures of my AR-11 restoration projects on this forum. Several of us have participated in discussions on these projects. My first advice is to search them out and read them, if you haven’t already done so.

As Bret posted, “It's almost a given that at least some of your capacitors are bad.” The Callins caps AR used are particularly prone to degrading over time. Unfortunately, the capacitors I used in my projects are no longer available. If you’ve read the capacitor discussions, you know that capacitor selection is a personal decision. Choose what you think will work best for you and fit your budget.

I’m curious to know what version of AR-11’s you bought. Do your AR-11’s have brass badges or Aluminum -black/silver? On the back, do you have mini-switches to the side of the speaker posts or switches above the speaker posts?

This will tell us whether your AR-11’s have the earlier two-board crossover, or the later single-board crossover.

>> Can you hear when capacitors need replacement? If so how would this condition "Sound"? <<

The simple answer is probably not, until you replace the capacitors and do a subjective listening test to a speaker with old caps and one with the new caps. I’ve posted a discussion on my subjective test of AR-11’s with old and new capacitors. I’ve also posted similar testing with AR-90’s. Depending on how degraded your capacitors are, the difference in sound “quality” can be astounding.

>> As I said in another post when I place my ear close to the tweeters in either speaker it sounds "Shaggy". <<

By “shaggy” sound, are you referring to a constant low level static when the speakers are powered and no music coming through or a general “shaggy” sound while music is playing? What are your attenuation switch positions? I’ve heard this static in AR-11 tweeters connected to several different audio systems when no music is coming through.

Another component that may need replacing is the resistors in the crossover. I’ve seen several burned resistors in the AR-11’s I’ve worked on. AR glued the resistors to the crossover board. This can cause the resistors to overheat and cook the resistor and the glue holding them to the board. If you find blackened resistors or glue on your boards, I recommend replacing the resistors with good quality wire wound resistors and elevate them above the board to keep them cool.

Enjoy your AR-11's, you bought some excellent speakers.

Rich

Link to comment
Share on other sites

Guest special rider

Hello all-

Rich- The pair I have now has the Blk/Silver badges and the switches are above the wire posts. Is this the later version?

Will the two different versions require different caps ?

I have done a search for old posts and have not found many that apply to caps in the 11s- I will look some more.

Thanks-

Link to comment
Share on other sites

Wayne,

>> The pair I have now has the Blk/Silver badges and the switches are above the wire posts. Is this the later version? <<

Yes, these are later version AR-11’s (what we refer to on this forum as AR-11B).

>> Will the two different versions require different caps? <<

Both versions use the same cap values and inductors. The big difference is in how the crossover is wired on the earlier, two-board crossover. The attenuation switches and resistors are different. I have reworked a two-board (referred to as AR-11A) crossover to the later configuration.

>> I have done a search for old posts and have not found many that apply to caps in the 11s- I will look some more. <<

Do a search for “AR-11” in the Acoustic Research forum. Look for these threads:

- Replace caps on AR11s, started Mar 20, 2005

- Subjective testing of AR-11 Speakers, started May 17, 2004

- AR 11 Rebuild Project, started Nov 23, 2003

These will give you a good start on AR-11 projects covered in this forum. They also contain pictures of original AR-11 crossovers and one I rebuilt.

Rich

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...