ProAc Tablette 50 - bad surprise when I got them home

[davstev]

Purchased a pair of ProAc Tablette 50 mini monitors from a nice local couple. They'd wrapped the speakers in towels and had them stored in boxes for many years, and finally decided to sell them. They're pristine. But they stored them in possibly bad orientations in the box, on the side, and possibly on the face (with covers on). No visible damage.

Getting them home and carefully unwrapping them, connecting, powering up, and slowly turn up the volume. A nasty gritty sound combined with low volume from one speaker. Something's wrong.

Swap sides, just to make sure that it's not my source (which I was pretty sure). No, it's definitely the speaker. Just one, the other is fine.

Lie the speaker on its back, and gently push on woofer. Voice coil rub. You can hear the light grinding... Nothing dreadful but you know this is the issue. The other speaker is not the same... Free unobstructed movement.

Questions to the group: can improper storage orientation cause this in what otherwise looks like a pristine speaker? Can anything be done to improve, if we're not dealing with a dislodged or damaged voice coil? Can I test anything with a DMM? Sellers are honest and very concerned and assure they were 100% when stored.

I'm planning to take it to a reputable speaker shop, but they charge $100 for an estimate. So if there's any assessment I can do beforehand...

Thanks!

 

[elitopus]

Weird things can happen to drivers when stored for a long time. From what I’ve heard, a driver should be stored flat, and rotated face up or down every once and a while. Like yearly. The weight of the cone can cause it to sag in one direction.

There’s also the chance the towel or whatever they were wrapped with put some weird pressure on the cone. Causing it to shift in that direction.

There are people who can disassemble the driver and recenter the voice coil. I had two drivers that had this problem and AKer GordonW fixed them for me.

If you know which way the speaker was stored, you could try flipping it on the other side and see if it still rubs. Maybe leave it that way for a while.

 

[GD70]

Don’t know much about these, or what model # woofer you have, but I did a quick woofer search and found this is on epay.
Proac / Seas woofer H775, 80 bux.

 

[elitopus]

If you can get a replacement driver for $80 that’s probably your best bet.

 

[davstev]

Thanks guys. A replacement will need to look identical too. Well, that's my super strong preference. I'll look into a replacement.

 

[davstev]

If you know which way the speaker was stored, you could try flipping it on the other side and see if it still rubs. Maybe leave it that way for a while.

Unfortunately I don't know which orientation it was stored in. I didn't take note in detail, other than to note that one was face down, and I'm not even sure which one it was. Had I known...

 

[MuseChaser]

This might be worth a try; it actually worked for me once.

Hook the speakers up and play music through them at a low level, just loud enough so you can hear the rubbing in the one driver. With one finger, LIGHTLY press at various places on the cone and see if very slight pressure anywhere clears up the problem. If it does, it indicates that either magnet has shifted or the driver is suffering sag towards the side opposite from where you're applying pressure.

Once you've found the right spot, exercise the driver with pressure there applied with three fingers (to spread the contact area),moving the cone enough to stretch the surround a bit opposite the sag. Repeat until the driver stays in the correct alignment. This actually worked for me after one of our German Shepherds knocked over a minimonitor on a stand.

You could also try storing the speaker with the point you found towards the bottom for a few weeks and see if that helps.

Redoing the surround is surprisingly easy, and would probably fix things, too

 

[davstev]

Thanks for the detailed explanation. I'm going to chat with the seller this evening and see what the next steps should be. This might be a good approach to attempt before anything else, ie. professional repair is attempted.