Modifying AR9 Bass Crossover section

[DavidR]

Thanks Harry.

The 9s will be for the next house which will have a good sized HT/audio room.

I will have 420 watts with 920watts dynamic headroom on the top end amp and 510 watts with 1000 watts dynamic headroom on the low end amp. (amp ratings are for a 4 ohm load)

[HarryM]

That will be awesome.

[Joe Rutledge]

David,

FWIW, I have both a set of AR9's & 90's also. As Harry commented the 9's do have a somewhat more extended bass, but as Harry and others have commented the 90's are very healthy there also. I would be happy with either in my listening space. Actually was, got the AR90's first, even my wife liked them, especially on Ella, Louie Armstrong, etc. Of course, it does matter what music you listen too and how much ultra low frequency material is recorded. Hard to do a "direct" comparison because of the age of the beasts and variables it presents - recently I have replaced most of the top end caps in the 9's except one of the harder to get at (don't have my chart handy). Simple steady state cap tests showed most of the 6/8/24 uf caps were 20% off or more. The AR9's did sound somewhat brighter after cap replacement.

My 9's sound fine with similar equipment to yours (Carver M1.0 mk2, etc), I was going to biamp, but illness got in the way and is limiting how much crawling around and experimenting I do (meaning none).

I was originally worried about not "having enough power" to drive the 9's loud with a single good quality amp. (note my prior AR-LST's would take everything an old Carver M4.0 could dish out). Frankly they seem to do fine since they are somewhat more efficient than the older AR's, I certainly could "play them louder" (more power), but...

To put it in listening perspective, they are in a old farmhouse, a very large room, what are 2 greek revival style parlors that are connected in the center, effectively somewhere around a 20' by 33' deep, 10' ceiling. Even with 1 amp, the 9's do very well in the primary listening space (front parlor).

Hope that helps,

Joe

[DavidR]

Thanks for the 'inside' perspective Joe.

[cARver]

Intersting thread here. I am lucky enough to own a pair of AR9ls (Lsi modded) and a pair of AR9 speakers. I have also been lucky enough to audition the 3a, 90, 91, 915,and 11 model speakers over the past year.

The AR9ls have been recapped with NPE caps for the 8,10 and 12 woofers. I used poly caps for the mid done and tweeter with bypasses. I was still not satisfied with the bass response until removing all of the poly fill and replacing with fiberglass. I used less fiberglass than the amount of original poly fill approx 60%. The results were incredible!! Super low bass response equal to my Definitive powerfield 15 sub from the 1990's. The sound is distinct for a 4way design with great detail unattained by any of the 3 ways recently auditioned. The tympani, saxophone and many voices are the clearest with the 9ls. Nothing negative about all the 3 ways, but it is a different audio experience.

So fast forward to the AR9 speakers I now have. They have been re-foamed but have original caps. The 8' chamber was unglued when I started working on them and I succesfully repaired it. All driver part numbers have been verified original as compared to the AR 90's. The sound is similar to the 9ls but the extended smooth lows are not as detailed/present in these 9s and the 8" woofer is a bit more active than the 9ls. I removed the poly fill as I did in the 9ls replacing with fiberglass at the same approx 60% without much change. The best way I can describe the current sound is gritty and lack of rubbery extended lows. I am not speaking of the mid dome frequencies regarding the gritty sound, I am describing the lower end.

I have positioned the speakers in several zones experimenting with best overall bass output with the 9ls always sounding better. The 9ls are less fussy with placement. 

I plan on recapping them and possible installing a switch as mentioned earlier in this thread to bypass the 2500 cap. My question is how much different is this load of this 9 woofer circuit as compared to the 9ls? Why didn't AR use a similar circuit in the 9ls/lsi? I do understand the 10/12 will have less load (higher impendence) than the 12/12, but looking for any comparison or contrasting of these speakers and circuits.

Thanks in advance for your response!