AR surround

Thanks for trying out these drivers, David. It is all very helpful. I have several spare OEM tweeters and two OEM midranges. I wonder how long these will hold up.

So sad. Robert was always willing to help with information and advice. RIP ra.ra.

This is what I eventually did. (see attached) Others have use more expensive poly caps, but I settled on the Daytons and I am very happy with them. Whatever you do, DO NOT put a Solen MKP capacitor in series with the UMR. You will get noise and harsh sound. I recommend using NPE's on the UMR of the AR90. Good luck!

I just fired up my pair of A60's after several years. I had recapped them with NPE's from Parts Express. My recommendation would be to stay with the stock Unicons that were supplied with these speakers as long as possible as they definitely sounded smoother before the recapping. Perhaps the old caps made them sound duller, but that was the way I preferred them.

Thanks ar_pro. As some of you may recall, I am a surround-sound enthusiast. I am also using a Parasound A52+ to drive the center (AR915), surrounds (AR90) and rears (Boston A70). This amp also has XLR inputs and produces 255 wpc into 4 ohms with all five channels driven. In two-channel mode, it puts out 350 wpc into 4 ohms. Thus, listening to quadraphonic and 5.1 recordings, such as Pink Floyd's Dark Side of the Moon, is a true showcase of the capability of the AR9 / AR90 / AR915 combination. Frank: Why do we have to wait until you organize your house? Guy's don't give a hoot about that stuff. 😗

Thanks, David. It converts to AB at a specified output.

I have just acquired a Parasound A21 to drive the AR9s. It puts out 400 wpc into 4 ohms. It is a class A / AB design that offers the benefits of class A performance at lower power levels. It's the biggest amp I've ever used to drive these speakers. The whole new signal path (Oppo 205 with ESS Sabre DAC outputted via balanced XLR cables into the preamp with XLRs into the A21) has resulted in noticeably improved sound over what I had before...a Lexicon RV8. And that was pretty darn good until the unit failed. Listening to what I use as reference recordings, the music sounds a bit more open, the highs are cleaner, and the sound stage is a bit wider and deeper. I can't really say if all this is due to the bigger amp or the purer signal chain. Perhaps a tad of all these upgrades.

Thanks, I had forgotten about that page. The section titled "Power Handling Capability" starts out by saying: May be used with amplifiers capable of delivering 400 watts continuous power per channel being driven to clipping 10 percent of the time on normal music source material. The key word is "delivering." It would appear that my amp, rated at 350 watts/channel continuous into 4 ohms both channels driven (0.05% THD), is close to that top AR specification. Further looking at the AR spec sheet, 50 watts per channel produces 107 dB SPL in a typical (rather large, actually) room. Of course, I am interested in amplifier headroom to deliver uncompressed sound rather than blowing my ears out at 107 dB. The quality of the sound when I switched from a Dynaco 40 wpc amp to a Dynaco 200 wpc beast to drive my AR5's was brutally obvious. However, I would suspect that increasing power from 350 wpc to 500 wpc (not even 2 dB) would be hardly noticeable with the AR9's.

A simple question: Does the AR9 maximum amplifier power rating of 400 watts refer to the amp's 8 ohm or 4 ohm spec?

I wonder how one knows if a midrange that is not totally blown out needs replacement?

Russell, The Lexicon RV8, which is long out of production, will safely handle four AR3a's. It is specified down to 2 ohms each channel with 7 channels driven. I currently drive two AR9's, two AR90's, an AR915 and two Boston A70's (for good measure as the rear channels.). The Lexicon beast handles them all gracefully even at high volumes. Here is one on ebay: https://www.ebay.com/itm/174695786607?hash=item28acae286f:g:PVUAAOSwAEBgVnge The newer Lexicon RV9 has a 4 ohm rating into multiple channels, but I have no experience with it. It is currently on sale, reduced from $6000 to $3600. That is still a big chunk of change. Good luck.

And if you look at these paged of the AR90 manual, they state that a catercorner placement as recommended by DavidR is an acceptable alternative. I am quoting the AR90 manual because the earlier AR9 manual does not seem to address this type of placement. (BTW, catercorner=catty corner=caddy corner = kitty corner.) http://www.classicspeakerpages.net/library/acoustic_research/ar-9_series_1978-1981/ar-9_series_manuals/ar-90_manual/ar-90_manual_pg11.html http://www.classicspeakerpages.net/library/acoustic_research/ar-9_series_1978-1981/ar-9_series_manuals/ar-90_manual/ar-90_manual_pg12.html

I agree. I currently have mine with a 12 ft wide short wall.

Can you try to place the speakers asymmetrically in your room? Or change your listening position such that it is asymmetrical to the speakers? That is AR's recommendation for when one is experiencing loss/cancellation of bass frequencies...Perhaps you are sitting in a null. Look at page 12 of the AR90 manual: http://www.classicspeakerpages.net/library/acoustic_research/ar-9_series_1978-1981/ar-9_series_manuals/ar-90_manual/ar-90_manual_pg12.html

How do they sound placed like that? I have about 1 ft on the side of the left speaker and 2 ft on the side of the right speaker. I have them towed in a bit and about 5 ft from the rear walls. I'm very happy with the results. I know that you are talking about placement distance to the side walls, but Julian Hirsch's review of the AR9's, states that they could not get the speakers to less than a foot or so from the back wall, but that placement had no harmful affects on the sound. I suspect that more people have made compromises regarding the placement of these speakers than those who have them set up exactly as recommended. If it bothers you that much, another solution may be to install a rather sophisticated equalizer. You can get one of these 31 band units, $220 at Amazon: https://artproaudio.com/product/eq355-dual-31-band-eq/

I'm using a Lexicon amp rated at 180 wpc into 8 ohms and stable with impedances down to 2 ohms. So heaven knows how much this beast is cranking into 4 ohms. The key is to have an amp that can deal with the low impedance of the power hungry AR9.

69AMX390, if you do decide to go the all NPE route, you won't suffer the agony of swapping out poly caps on that 24uF UMR series capacitor. On that UMR cap, I tried a Solen MKP which was abominable. Then I went to a Jentzen Cross Cap which wasn't as bad, but still incompatible with the UMR. I finally settled on Mundorf E-Caps NPEs with Dayton F&F bypass caps. I didn't try any real pricey poly caps (i.e. Mundorf Supreme) because doing so would have been prohibitively expensive given my setup. (I have AR9's, AR90's, and AR91 in a 5.1 system.)

My original AR-9's from 1978 also do not have the foam inserts, but my AR-90's do have them.

Wonderful restoration, Chris. Enjoy them! One question: What is your technique for popping out those detentions in the midrange domes?

Yes, one has to wonder if there was a very bad run of those 6 uF Callins caps...a manufacturing "excursion" as it is often called. The ones I took out of my AR9's measured 26.8 uF and 28.0 uF.

Doug, Here is my agony and ecstasy of reworking my AR90's from 2017. It particularly focuses on the difficulties I had with getting the UMR to sound to my liking. Hope you find it helpful along with the many other threads about working on the 9 series.

Chris, I second Stimpy's sentiments about the new NPE's not sounding as good as the original Unicon NPE's. I replaced the Unicons in a pair of Boston Acoustics A70's with new NPE's. The result was absolutely awful. I mitigated the issue by adding resistance and F&F bypass caps; but I should have just let the Unicons be.

Yeah, the tech part of my brain told me that a restoration was doable. The financial part of my brain said that the cost might justify the results. But my back said...no way! LOL

Carl, may he rest in peace, told me that capacitors needed to be +/-15 order to produce a noticeable difference audio wise. I've used that figure as a benchmark, but it's moot because I replace all the caps when recapping speakers since I'm in there anyway.

Thanks for bringing this to our attention . One has to wonder how those domes get pushed in. It must be the handiwork of young fingers. The water damage doesn't look too bad...It doesn't seem like it was in a flood, but closer inspection is probably necessary. This guy isn't far from me, but with AR9's, AR90's, and AR91s in the house, I don't have the space.