AR M5 Holographic - Wrong Drivers, Sound Horrible, Worth Saving?

[Johnny_Law]

Edit: See Post #20 for good news

So a pair of these followed me home the other day for no apparent reason ... I thought they looked cool and different and thought it'd be cool if they surprised me. I knew the mids were wrong (they look like car door drivers) but was promised they "bumped." Got them home, took them apart, to find:

Evidence of foam failing on the original drivers (foam pieces all over the inside the cabinets), and lo and behold, non-original drivers in place of the original woofers. One has a tiny magnet with a low DCR (maybe a 4ohm driver), the other a larger magnet and a higher DCR (maybe an 8ohm driver).

Other drivers are good the (non-original mids and what might be the original tweeters).

So I cleaned them, brought them inside and hooked them up. They sound horrible. It sounds like the car door mids are the other drivers actually producing audible sound.

I'm at a fork in the road. Do I shrug it off and throw them away? Or do they really hold enough promise to find original woofers and mids, rebuilding the crossovers, and hoping for the best? Are they worth saving?

Couple threads I read along the way ...

http://audiokarma.org/forums/index....earch-m5-holographic-imaging-speakers.363432/
http://audiokarma.org/forums/index.php?threads/ar-m5-holographic-imaging-advice-please.96418/
http://audiokarma.org/forums/index.php?threads/acoustic-research-holographic-m5.410885/

Thanks in advance,
Ryan

 

[jberger]

Definitely not the original midranges (with the coax tweeter)!.

I found these to be pretty impressive as a line; I've had M1's, M2's, M6's, and a pair of M5's. They are at their best when played away from the side and back walls, and in an open environment you can walk right into the stereo image. The M5's had a single 8" woofer; the M6's had two, and are a little taller. There's also a metal grille for the top section.

The woofer in mounted on a slide-in board that goes in from the bottom; when you can get it to slide out, it's an easy refoam. Of course, if they got too sloppy with the glue, then you can't slide them out, and they end up like the pair in my shop, with one repaired and one not...

Do you have part numbers visible on either of the woofers?

 

[onwardjames]

I'm a hopeless romantic, so I'd source some original drivers and have at it. Good luck.

 

[Johnny_Law]

Thank you both. One of the woofers is an Aiwa drive unit, I am not sure if the other had marks on it. I should have taken pictures when I removed them, I'll pull them again soon and snap some pics.

I guess the follow-up question would be: who knows what the correct mid / woofer drivers are? And are there any suitable aftermarket equivalent drivers?

 

[michiganpat]

my old M5's were missing the original mids...I found a pair from some late 90's/early '00's AR "the edge" speakers that fit quite well and sounded very good. I had to do a little trimming to fit the shielded magnets of the mids.
if looking for other replacements, remember, on these the mids basically run wide open, using the off axis response of being in the baffle at 45* to handle their rolloff to the tweet. I'd be looking for probably a paper or poly midwoof of the proper dimensions that has a clean rolloff when listened to 45* off axis in the 3khz range.

mine had the original woofers and tweets, and I refoamed the woofers, sounded excellent, I regret selling them. watch ebay, I've seen the top pods show up. as far as the woofer, the design is a bandpass config, I can't remember if it's a 2nd order (one side sealed, the other ported) or 4th order (both sides ported). I want to say it's 4th, with one port upfiring and the other down. there's online calculators, and you can measure the port cross sections, lengths, and calculate each chamber's volume, then start playing around with t-s parameters of different woofers to see what would work best....

while they may not be true original, there's no reason they can't still sound good....

 

[michiganpat]

also, don't quote me on it, but the mids _might_ be the same drivers as the woofers from the "fun partners"......which there are some on the 'bay right now for reasonable $$

 

[jberger]

I opened up the top section of my M5s. Here are the drivers. Tweeter first

And midrange

 

[Johnny_Law]

Awesome thanks so much! I'm asking the Google gods to track down details using those numbers and coming up empty ... but I'll continue to look.

(In the meantime I did miss a pair of top sections that were on the auction site - thanks Pat.)

 

[baco99]

Most of the drivers are available via Parts Express. I may have the right woofers, I have to check.

Check classicspeakerpages.net and see if you can get part numbers. Those numbers on the backs of the magnets in the pics above are just batch numbers. You need to know Part numbers.

Here's what the tweeters look like, but there were made in three dome materials, coated (silver) cloth dome, coated (black) cloth dome, and poly dome.

http://www.ebay.com/itm/NEW-Acousti...513840?hash=item231b65d4f0:g:0SwAAOSw9mFWK7~o

http://www.ebay.com/itm/NEW-Acousti...145262?hash=item2325fc45ae:g:28wAAOSwl9BWLWFK

Hi5electronics is an eBay presence for Parts-Express.

Chances are the tweeters are still in the cabs and you just need to hook them up. The mid-woofer will need be bought. The inner LF woofer may be blown, or just connected wrong. The inner ones should have rubber surrounds, but I could be wrong about that.

 

[onwardjames]

way to go, Baco!

Hope to see these up and going soon.

 

[jberger]

I've had M5s and M6s, and the inner woofers have had shredded foam surrounds. If you remove the base panel with the feet from the bottom section, the baffle board slides out, and you don't even have to dismount the woofer to refoam.

 

[Johnny_Law]

Well I took these back out to give it another shot. I removed all drivers and found out the tweeters, while original, are both dead. So - I'm hunting for the full driver compliment here.

If I can't find originals, I'll find equivalent drivers. I see that PE has original style tweeters, but my diaphragms are metal and not cloth or plastic.

Who knows anything about the specs of the original drivers? If I can't find used ones I'll try to find new equivalents.

 

[quiet]

Do you feel like you're rolling the dice with new drivers?

 

[Johnny_Law]

I feel like I already rolled the dice and lost

 

[quiet]

Not yet, not yet. It's all in the recovery.

 

[tarior]

Anyone know if those were original with a paper cone woofer, or poly?

 

[tubed]

Poly woofers.
I once owned both the M1 and M2 and both seemed to sound good until I realized they were actually quite fatiguing to listen to for more than a half hour at a time.

 

[baco99]

Parts express has the original tweeters

 

[michiganpat]

the parts express tweeters I think are for the M.5-M4, as the M5/M6 had titanium domes. the original mids were rubber surround, poly cone, but the woofers in the cabinet were paper cone/foam surround

 

[Johnny_Law]

So, I ended up giving the M5s away before a recent move. But I hate abandoning projects.

Turns out, luck was on my side! I stumbled across another pair of M5s, these with all the right drivers! Woo! First step, confirmed that the drivers all work, and now to refoam the woofers.