AR9 Problem

[Guest Barrydor]

I recently acquired a second pair of AR9s which are currently being auditioned at a friends house. The speakers were purchased from the original owner who took reasonably good care of them. The cabinets and grills are in mint condition.

The original owner replaced all of the woofers. I believe that the bass extension of this pair of AR9s is not quite as deep as my other set, which has the original woofers. This is a story for another day.

The problem I am having with the new AR9s is they have a boxy, closed-in sound and a very noticable "honky" character in the lower midrange. This is completely unlike my other AR9s and other pairs I have heard. Something in this pair seems definitely broken.

The original owner had a problem with imaging. I helped him trace this down to the fact that one of the lower midrange drivers was wired out of phase. Although I have not opened the speakers yet, I am assuming at this point that he wired them properly and sealed the drivers when he reinstalled them.

The lower midrange drivers look identical to the originals from the outside as far as I can tell and they look brand new, including the foam surrounds. Since the woofers were replaced, I think it is safe to assume that the lower midranges were probably replaced also.

I know it is a little preemptive to ask for advice before I open the speakers up to see what is going on. My question here is, has anyone had experience with replacement lower midrange drivers for the AR9? Can anyone confirm the sound of the replacement driver compared to the original? Has anyone experienced and resolved the problem I have described with an AR9?

Thanks,

Barry

[Guest]

It might depend on the vintage of the replacement 8" drivers, Barry...a pair that I bought from AB Tech circa 1991, sounded fine when compared to a 9 with original drivers. It sounds like you're going to have to get a look at the drivers at some point, and compare them to an original 8". Are original-spec drivers still available?

From your description of both the bass and lower-midrange deficiencies, your new 9's could have a crossover problem...might the original components have been "upgraded" by the previous owner?

[Guest Bret]

>The lower midrange drivers look identical to the originals from the outside as far as I can tell and they look brand new, including the foam surrounds. Since the woofers were replaced, I think it is safe to assume that the lower midranges were probably replaced also.<

As I was reading your description of the sound "crossover!" sprang to mind immediately. Now, what's bad in the crossover? I dunno, but for some reason a 25-year-old memory was whispering "chokes" in my ear. Without being there that is a really sad attempt at acting psychic, you know. And, of course, that makes no sense since a choke is a hard thing to melt, really. It'll be interesting to hear what you found when you get to it.

I do have a bookmark (on another computer) of a link to what I believe is a pair of 8" midrange drivers (used). Are your other 9's 8" drivers original? The over-sized dust-cap is a dead giveaway.

Bret

[Guest Barrydor]

I doubt the original owner made any crossover changes or upgrades, but I need to verify this.

My AR9s have the original 8" lower midrange and the "new" AR9s also have the oversize dustcap.

Even though I have two pairs to work with, they are in different places. I hope I can resolve this without switching drivers back and forth.

I will be working on this Friday and I will surely post the results. This is a very interesting problem.

Barry

[Guest Bret]

>I will be working on this Friday and I will surely post the results.<

Barry,

What did you find? Oh, and did you pull the upper midrange drivers? Were they the 200028 drivers?

Bret

[Guest Barrydor]

The original owner had a problem with imaging. His description of the problem led me to advise him to check the wiring of the lower midrange drivers, which had apparently been refoamed or replaced previously.

Sure enough, one of the lower midrange drivers was wired backward. Correcting the wiring solved his problem.

I advised him to use rope caulk when he reinstalled the drivers, but unfortunately he used only the original gasket, which was shredded and in very poor shape. Apparently, air was leaking from around the driver and ruining its performance. When I reinstalled the driver with rope caulk, all was well.

There was also an anomaly in the room which accented the output of the lower midrange driver. Until I figure out what the problem is, I simply set the output to -3dB using the switch. The speakers now sound incredible, just like my other set!

The lower midrange drivers in these speakers were original. I did not pull any other drivers, but I have no reason to believe they are not original as well.

Barry

[Guest Bret]

>Sure enough, one of the lower midrange drivers was wired backward<

Yep, that'll sure goof-up an image.

Bret

[tysontom]

>The original owner replaced all of the woofers. I believe that

>the bass extension of this pair of AR9s is not quite as deep

>as my other set, which has the original woofers. This is a

>story for another day.

>

Barry,

Were these replacement woofers the AB Tech Tonegen replacement woofers? They are characterized by the foam decorative trim, about 1/8-inch thick, around the edge of the frame with neatly-trimmed cutouts for the screw holes. The cone is a brownish-gray color. These are excellent replacement woofers, but are stiffer and actually have a slightly higher resonance frequency than the original woofers. They improve in time, but this could be part of the percieved low-frequency problem -- if indeed it is the Tonegen woofer. The only other "replacement" that would fit the unique truncated AR 12-inch woofer cutout would be a surround replacement to an original woofer, so it must be the Tonegen woofer.

>The problem I am having with the new AR9s is they have a boxy,

>closed-in sound and a very noticable "honky" character in the

>lower midrange.

>

>The original owner had a problem with imaging. I helped him

>trace this down to the fact that one of the lower midrange

>drivers was wired out of phase. Although I have not opened the

>speakers yet, I am assuming at this point that he wired them

>properly and sealed the drivers when he reinstalled them.

>

I would just about bet the farm that someone did go in and change the lower midrange drivers, possibly with one of the other 8-inch drivers (possibly the 8-inch universal woofer or something). First of all, for the speaker to be wired out of phase, there is a 99% chance that someone in the field did that, and a 1% chance the factory had a miscue on wiring the speaker. Beleive it or not, there was a great deal of quality control going on at AR, even into the late 1970's and early 1980's. The correct part number for the AR-9 and AR-90 lower-midrange 8-inch driver is: AR#1200027-0. Pull one out and see if it has this number.

--Tom Tyson

[Guest Barrydor]

>Were these replacement woofers the AB Tech Tonegen replacement

>woofers? They are characterized by the foam decorative trim,

>about 1/8-inch thick, around the edge of the frame with

>neatly-trimmed cutouts for the screw holes. The cone is a

>brownish-gray color. These are excellent replacement woofers,

>but are stiffer and actually have a slightly higher resonance

>frequency than the original woofers. They improve in time

From your description, Tonegen replacements are exactly what they are

>I would just about bet the farm that someone did go in and

>change the lower midrange drivers, possibly with one of the

>other 8-inch drivers (possibly the 8-inch universal woofer or

>something). First of all, for the speaker to be wired out of

>phase, there is a 99% chance that someone in the field did

>that, and a 1% chance the factory had a miscue on wiring the

>speaker.

I have no doubt that someone replaced them in the field or removed them to have them refoamed. I will pull one out again and check the part number

Barry