NON POLK question (Acoustic Research speakers)

Schurkey

I actually listened to these speakers for the first time earlier this evening.

1. I re-foamed all six of the 8" drivers: Four bass drivers, two midrange drivers.

2. I glued the "surround" of one tweeter to the housing. I could actually pull back the surround and see the windings of the voice-coil! The other tweeter still had the surround attached. This is seven out of the eight drivers that I had to attend to. I have to concede that the re-glued tweeter cannot be functioning properly because there was no ferrofluid still in it. IF (big IF) there's any ferrofluid still in the other tweeter, I'd expect it to be thickened and interfering with proper treble response.

3. The receiver I'm using to drive these is the ancient JVC from my garage system. I popped the cover off to blow the dust out, and was greeted by three capacitors that have messed the bed. Both 6800uF power supply caps have leaked, along with a 220uF cap of unknown employment. Replacement parts will be ordered in the next few days.

4. The fabric speaker covering (socks) have been hand-washed and dried, but not yet re-installed as I still need to remove bass drivers to access the crossover (and I don't trust the tweeters yet, either.) My intention was to pick up a pair of Tang Band tweeters ( https://www.parts-express.com/tang-band-28-847sd-shielded-neodymium-dome-tweeter--264-822 ) as they are quite extended into the midrange (850 hz), and have a smooth impedance and frequency-response curve in the crossover region. Anyone care to share any wisdom or experience with these?

5. Logistics demanded that I make them playable even though I don't have the fresh capacitors in the crossovers yet. I'm spending most of my day cleaning-up, painting, and in other ways preparing my mother's house for sale. Rebuilding these speakers has been my diversion from ammonia fumes and drying Latex paint. I'm therefore listening to unfamiliar speakers in an unfamiliar environment which is acoustically crap due to the large, "L" shaped living/dining room, with furniture and cardboard boxes stacked willy-nilly all over creation.

Despite all this, I'm favorably impressed with how the speakers sound. There is bass in abundance; well below 60 hz although surely not to 20 hz. AR claimed 32 hz, and I believe them now. (I hear George Grand laughing) I'll let the surrounds "break in" for awhile, then throw on some test CDs and do some Scientific Testing using the RACHEL (RAdio shack CHEap Level meter) equipment protocol.

Treble seems a touch ragged; which does not surprise me at all. I'm surprised there's ANY treble, let alone the "reasonable" quantity/quality that I have. I expected nothing from the original tweeters. It may be that they will die shortly--they don't have a stellar reliability rating. For now, I've got < $50 in these things, and I'm stoked.

Photos, and crossover rebuild to follow.

Schurkey

Saucer used as a glue-clamp, excess glue oozed out and was cleaned-up later.

wisnowski1

I've never refoamed anything but am planning to soon. in my research i found this

https://www.youtube.com/watch?v=NpMYZq-qQNo

seems like a good option rather than replacing dust caps.

westmassguy

wisnowski1 wrote: »

I've never refoamed anything but am planning to soon. in my research i found this

https://www.youtube.com/watch?v=NpMYZq-qQNo

seems like a good option rather than replacing dust caps.

Absolute BS

Schurkey

For whatever it's worth, I did not cut the dust caps. I did not shim the voice-coils. I did not run 30 or 50 Hz tone through them. Either the spider did an excellent job of keeping the voice-coil centered, or these old drivers have a HUGE gap for the voice-coil...or I'm the Oral Roberts of speaker re-foaming. I did spend some time 'n' effort to center the cone/spider up/down in the magnetic gap, so the spider was flat when the surround glue was dry.

There's no scratchy sound of misaligned components on my drivers. And they sound--as I said earlier--surprisingly good. I'm astounded that the tweeter I re-glued works at all.

OTHER drivers may be much more difficult to work with, but I just don't know how these AR drivers could be screwed-up in the process of re-foaming.

All other work on these speakers (and the receiver powering them) has stopped. I'd like to get the crossovers re-capped, make a decision on the tweeters, and finally get the socks reinstalled, but I'm way behind on the house. More to follow, but not soon.

In situ: