Suggestions for replacement woofer Acoustic Research AR-1 Hi Res

[maskinisten 59]

Sometimes i notice a ''thump crackling'' sound from one of the woofers of my powered tower speakers, there is no scratch sound from the woofer if i push it in or out by hand, the ''thump crackling'' sound seems to come at a spesific frequency. 

Strangely enough, the woofer measures ok. 4 Ohm, but i guess there still can be something wrong with it?

I have been looking around the internet for spare parts, but no luck so far. 

These speakers have a built in 500W Sunfire plate amp to drive the 15'' woofer.

Already spent a couple of $1000 for repairs on 3 of these plate amps, so i dont want to give up on these speakers, i also think i will have to spend a lot to get something else performing as good as these.

 

Overall specs of the speaker:

Frequency response: 18-23000 Hz +- 2 db

The crossover frequency for the woofer is at 120Hz 

The internal volume of the speaker is about 92 liter or 3,25 cubic feet, the cabinet is sealed.

I dont know the sensitivity of the woofer itself, but overall its 95db 2,83V 1/m

 

I've looked at the parts express site, there i found this Dayton woofer RSS390HF-4 15" Reference HF Subwoofer 4 Ohm

Here is the pdf with full specs of the Dayton woofer

Can this woofer be used to replace the original woofers, or maybe someone have other suggestions?

 

~~Leif

 

 

 

 

 

[4krow 6,519]

You might take a close look at the drivers surround material. Not always easy to catch, but possible there is a rip.

[maskinisten 59]

32 minutes ago, 4krow said:

You might take a close look at the drivers surround material. Not always easy to catch, but possible there is a rip.

Thanks, yes i just checked again, nothing suspicious to see, i might have to remove the woofer to really be able to move the surround foam, but so far it seems tight glued to the cone and no cracks.

Would it also be possible that the magnet can get out of alignment? 

Edited December 3, 2021 by maskinisten

[PMAT 2,037]

I wouldn't give up on them either. Those are underrated and wonderful speakers. I had a smaller version of that speaker and I am so bummed I sold them. I would be hesitant to replace them with non stock units as its very difficult to match a given design. Sometimes a woofers surround isn't damaged but is weak from years of use. This allows some over excursion or general misalignment. Assuming no other issues with the driver I would have new surrounds put on both speaker's low drivers. You can do it yourself but you are limited to the one surround you buy. A speaker repair place can compare the old surrounds to all available new ones and get the best match. I would also add some bracing to the cabinets while they were apart. Nothing big so as not to change the internal volume. Those are acoustic suspension (sealed) speakers and are fairly rare in this world of ported offerings. Make sure there are no air leaks as well because that changes the suspension which relies on air pressure in the cabinet to prevent over excursion of the woofer.

[maskinisten 59]

6 minutes ago, PMAT said:

I wouldn't give up on them either. Those are underrated and wonderful speakers. I had a smaller version of that speaker and I am so bummed I sold them. I would be hesitant to replace them with non stock units as its very difficult to match a given design. Sometimes a woofers surround isn't damaged but is weak from years of use. This allows some over excursion or general misalignment. Assuming no other issues with the driver I would have new surrounds put on both speaker's low drivers. You can do it yourself but you are limited to the one surround you buy. A speaker repair place can compare the old surrounds to all available new ones and get the best match. I would also add some bracing to the cabinets while they were apart. Nothing big so as not to change the internal volume. Those are acoustic suspension (sealed) speakers and are fairly rare in this world of ported offerings. Make sure there are no air leaks as well because that changes the suspension which relies on air pressure in the cabinet to prevent over excursion of the woofer.

 

Thanks for the advice.

Yes these speakers are rare and hard to come by, i also think they never got the recognition they deserved, i think part of it is because of the history of the AR brand, every time the brand name was sold they seemed to lose some of its reputation.

But for this Hi Res series as well as the HO series while they were owned by Recoton were of good quality, a peek into their web site these days just make me wanna cry!

[PMAT 2,037]

Mine were 12 inch woofers and passive units. The mid/high design was very effective. I had about 10 pair of speakers at the time and sold off some nice stuff including some electrostats. I tried to hunt down more info on your drivers to no avail.

[garyh 460]

4 hours ago, maskinisten said:

the ''thump crackling'' sound seems to come at a spesific frequency. 

 

It may not be the driver... have you checked for sympathetic sources?  Anything from inside the speaker to outside, around it--something vibrating at that frequency.  Buzzing and rattles can be notoriously difficult, often, to isolate. 

 

Just a thought.  Good luck!

[4krow 6,519]

Yup, were pullin' drivers. Investigation is a given. It gives you a chance to take a look around inside, so that is half the fun. Hoping that everything is accessible. I am up with the idea of checking for air leaks, and possibly bracing the cabinet. 

 I don't think that speaker magnets can be out of alignment so easily, yet when it comes to age of the suspension, that is another matter. Hope that you will take some good, in focus shots for us. 

[maskinisten 59]

Yes i will remove the woofer and give it a thorough inspection one more time, this time i will also try to play some test tones on it while its out of the cabinet.

Thanks for the support and suggestions, i really hope i have overlooked something.

 

[Nahash5150 10,629]

44 minutes ago, maskinisten said:

Yes i will remove the woofer and give it a thorough inspection one more time, this time i will also try to play some test tones on it while its out of the cabinet.

Thanks for the support and suggestions, i really hope i have overlooked something.

 

 

A sympathy check is a wise first step as Gary suggested. Other than that, It could be the former is misaligned or malformed, which can cause a racket at certain frequencies, but not go completely bad. The tolerance of the former and winding inside the magnet is very tight, and so even a slight over-excursion can malform the alignment.

 

It would be best not to use it - the next likely failure is damage to the coil wires themselves, then it's bye bye for good.

[maskinisten 59]

Update, i removed the woofer and gave it a thorough check again. 

Everything seems solid and well glued together, i also connected the woofer outside the cabinet and played a test tone through it, at least i now know for sure that its the driver itself making noise.

 

I also took a few pictures

 

 

 

[maskinisten 59]

Thinking out loud.. what would happen if something like hard dust particles came inside the vent and in between the coil and magnet? 🤔