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AR9 Questions

Guest Barrydor

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Guest Barrydor

I purchased my AR9s new 23 years ago about a month after they came on the market. At the time I purchased them, I viewed them as a lifetime investment. So far, they have not let me down.

Over the years, I have re-oiled the woodwork, replaced the grille cloths and the binding posts, and refoamed the woofer and the lower midrange surrounds. I have also upgraded the lower midrange driver and added cone feet.

I have a couple of questions about the AR9 speakers:

First of all, the speakers were placed in storage in a garage in Maryland for about a year. Because of this, they saw freezing as well as hot and humid storage temperature during this time. The speakers claim to have used "magnetic fluid" in the upper midrange driver and the tweeter. I have never understood this concept as it seems a non-magnetic fluid would be necessary to fill the gap and conduct the voice coil heat to the frame. Regardless of the chemical composition of the fluid, I would have expected time and possibly the storage temperature extremes to have degraded the integrity of the fluid. Is this an issue with this type of driver design? Should these drivers be rebuilt?

Also, if one looks at the pictures in the owners manual, one will see that the acoustic blanket has a rather large square opening for the upper midrange and a large round hole for the tweeter so that the entire front plate of the tweeter driver is exposed. If one looks at the "truth in listening" ad photos however, it shows filler pieces added to the acoustic blanket which fill the upper midrange opening up to the aluminum horn surrounding the driver and the tweeter opening almost up to the dome element. I have never been able to find these fillers. Did AR supply them with later speakers or did they decide not to produce them?

In my case, the crossover capacitors are original. Is it likely that I will gain a substantial increase in performance by replacing the nonpolar electrolytics? Do they have a useful lifetime? Do they drift in value and/or become leaky over time? Is there a danger of them failing at this point in their life?

When I replaced the woofers, I was surprised at how "chintzy" the internal wiring is in the speakers. Stranded, tinned wire is used and is crimped, not soldered to relatively cheap Faston connectors. There was visible oxidation on the Fastons and the driver terminals. It seems that rewiring the speakers with some decent solid, silver plated wire and some decent Faston terminals with some Caig Pro-Gold in the right places would really do some sonic good. But I am not sure if replacing the caps would be beneficial while I am in there. Any opinions?

I would like to get my hands on readable files or hard copies of the assembly drawing, crossover assembly drawing and speaker schematic for the AR9. I would be happy to pay someone to reproduce them and send hard copies to me.

Thanks in advance,


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Hi Barry

>"magnetic fluid" in the upper

>midrange driver and the tweeter.

It will not have degraded.

It is a magnetic fluid, aka "Ferrofluid". It is chemically stable over temperature and pressure ranges that are not suitable for life as we know it. It is one of those things that came out of NASA. It is a pure oil that does not outgas significantly, with coated FE2O3 particles in suspension. Leave it alone. It is very messy stuff and stains clothing. It is used in 99+% of all the hard disk drives ever built. I am a hdd Design Engineer.

>element. I have never been

>able to find these fillers.

Mine do not have them either.

>Is there a danger of

>them failing at this point

>in their life?

Yes. See the article on rebuilding the AR94 on this site for more info.


>some decent solid, silver plated

You want STRANDED silver wire, NOT solid.

>I would like to get my

>hands on readable files or

>hard copies of the assembly


The drawings on this site will come up using Netscape as the viewer of the .TIFF files.


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