Rebuilding AR 9 and 90 Speakers

Vintage Asylum

Classic gear from yesteryear; vintage audio standing the test of time.

The 9's and 90's were and are good speakers. But they are now approximately 25 years old now, so you can expect them to be a little tired and â€˜long in toothâ€™.
So is it worth while spending time and money on rebuilding these?
Absolutely yes! Not only can these speakers be rebuilt, but in the process some of the inherent design/build flaws can also be corrected that prevented them from being truly outstanding speakers.
If you follow the improvements listed here, the results are quite staggering to say the least. Your "antique" AR's, which are already pretty good speakers to begin with, will literally trounce many speakers that cost $10K or more. Feed them with some REAL wattage and you'll be amazed with the finesse, grace, detail, imaging and power that these "old pieces of junk" can deliver.
I am indebted to Sean for a posting in www.classicspeakerpages.net that gave me the encouragement to tackle such an undertaking. Full details and schematic of the AR9 can be obtained at www.arsenal.net/speakers/ar/ar-9/ar9.htm.
Ok where do we start? First dismantle the speaker entirely, and renew the flex rings to the woofer and mid-range speakers.
1. Improvements to the speaker cabinet.
The speaker cabinet has one brace in them and it is located just above the woofers going from side to side. While this is the place that a brace is most needed, the cabinet is quite flexible and resonates like mad due to the lack of bracing and internal damping. To correct this add a brace from the baffle to the rear panel and from side to side up higher in the cabinet. (A closet rod Â¾â€ round will do nicely.) If you do things right, you can tie these two braces together, adding even more rigidity to the cabinet. I placed one of my braces going from the very top section of the 8's chamber to the rear panel and then ran another brace just above that from side to side.
Besides adding the bracing, sound damping sheets won't hurt anything and will help lower the Q of cabinet resonances. I would avoid working with lead and use some inexpensive but reasonably effective damping sheets that Parts Express sells. Try either 268-010 or 268-030. You can easily use 4 - 10 sheets per cabinet depending on how "gonzo" you want to go. My suggestion is to stagger the sheets apart a bit at random distances, which will help break up any major nodes that might be occurring.
Make sure that the cabinet is sealed as best possible.
2. Improvements to the speakers.
While we are talking about damping resonances, here's one of the biggest tricks that you can do to drastically improve ANY speaker that uses stamped metal baskets. Apply a material to the metal basket to dampen the ringing that takes place. If you doubt this is happening, take the drivers out of the box and "flick" the basket with your finger. While the 12's will ring quite noticeably, the 8" driver will sing like your playing a bell. To reduce this effect I have used a hard-curing cement like "liquid nails" or â€œmetal epoxyâ€™ to spread a layer on the stamped basket. Let it set up till hard and then spread another layer on.
3. Improvements to the Internal Wiring
As far as upgrades go, get rid of the thin-gage factory wiring and bypass the factory attenuation circuit. These speakers already sound "warm and full", so you shouldn't need to attenuate any of the upper frequency ranges at all. This DRASTICALLY opens up the sound and shortens the signal path. You get rid of several feet of low grade wiring, the resistors and the switches. ALL of the lower midrange, upper midrange and treble signals had to pass through those junky switches, so get rid of ALL of it. Besides that, it makes the system so much easier to re-wire it's not funny. You can leave the switches and board in place for cosmetics, but bypass all of that electrically.
Use the wire of your preference. I would recommend NOT using "zip" type cord as it is highly inductive and rolls off the top end. Buy a good quality multi-stranded thick gage copper wire. If you want something cheap that works reasonably well, try using some Carol wire and cable that you can get from Parts Express. Use 100-728 configured as a Star Quad for the 12's and 8's and 100-710 for the domes.
Now that you've gotten that far, replace the stock cheap binding posts that these speakers came with larger all metal units from Axon or from Parts Express 091-340's. This way, you can use some real wire like the AR's deserve.
3. Improvements to Cross Over Network.
Upgrading the caps is a very worthwhile venture. They are 25 years old now, so you can expect them to be in less than optimum shape. Doing this will not only bring the speaker back within spec, it typically helps to level out the tonal balance a bit. If one studies the frequency response charts of the 9's the lower frequency range is slightly elevated above that of the midrange and treble. In effect, the response really is "full bodied" due to the elevated low frequencies, particularly in the "warmth" region, and "smooth", due to the slight shelving of the upper frequencies that takes place. By spending as much as you can afford on quality caps (such as Sonicapâ€™s etc) this can be alleviated, and it will actually produce a speaker that sounds more open, spacious and may actually measure more linearly.
Happy Listening,
JoeD

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

Topic - Rebuilding AR 9 and 90 Speakers - Joe D 09:42:14 04/18/07 (4)

Re: Rebuilding AR 9 and 90 Speakers - kimc 02:42:29 04/28/07 (0)

Re: Rebuilding AR 9 and 90 Speakers - pete the bully 19:42:14 04/18/07 (2)

Listening to rebuilt AR 9 Speakers - Joe D 16:12:54 04/19/07 (1)

LOL but thanks - pete the bully 17:21:05 04/19/07 (0)

You can not post to an archived thread.