Distorted sound after not using speakers for years

[Kastner]

It must be 9 years since this pair of Mission 701 speakers have been used and the sound is distorted especially with the bass and at low volume. This happens using difference amps. The woofers were stiff to begin with. I had to coax them to start moving. Apart from this they appear as new with no damage. Any ideas?

 

[nopiano]

Gravity can get the better of cones, and the voice coil scrapes on the magnet. If you can unscrew the bass drivers and rotate them 180 degrees you *might* find they work.

If they’ve been in a cold garage or damp place, they’ll have suffered, possibly beyond a simple repair. However, a few days unused in a nice dry room might help them recover.

 

[Gray]

Gravity can get the better of cones, and the voice coil scrapes on the magnet. If you can unscrew the bass drivers and rotate them 180 degrees you *might* find they work.

If they’ve been in a cold garage or damp place, they’ll have suffered, possibly beyond a simple repair.

Yes, it does sound like the coil could be scraping. There may even be some rust in the gap.

With finger and thumb either side of the coil ( to give even pressure) gently move the bass cones to see how the movement feels.

 

[gasolin]

Yes mabye a rusty voice coil og binding posts

 

[hybridauth_Facebook_100004211376004]

with some mission 701's.....the bass driver would become noisy and vibrate due to the allan bolts working themselves loose.....they would never tighten back up...went through a couple of pairs like this.....this is back in the early oo's.

 

[Kastner]

After further inspection thanks to the above comments the voice coil is rubbing within the magnet. Unfortunately I can't remove it since the cone is glued in place hiding the magnet bolts. I have tried rotating the speaker but it still rubs.

 

[Gray]

Looks like a couple of replacement mid/bass drivers are your only option.

Direct replacements would be nice, but possibly more than you'd want to be paying.

Might be worth looking for some sensibly priced equivalents.

 

[davedotco]

See if you can remove the bass drivers but leaving them connected, with the driver sitting on it's magnet, play some bass notes so that you can hear the problem.

Then, press down on the frame of the speaker, do it on opposite sides, say 12 and 6 o'clock, then 3 and 9 o'clock and see if that makes a difference. This will shift the allignment of the coil in the magnetic gap, you should be able to hear the difference though you may have to press quite firmly.

If you can find a position where pressing eliminates the rubbing of the voice coil, then mark the positions, when you refit the bass drivers use spacing shims at the points 90 degrees from your marks and bolt the diver in firmly, the shims should distort the frame in the same way that pressing the unit did and could solve your problem.