0
\$\begingroup\$

I have a set of speakers which has been standing in a humid place for a few months. One of them still works perfectly fine, the other not so. The other speaker creates a very static noise, barely rendering it's audio source.

Following link is a recording of what it sounds like: Good speaker vs bad speaker

The speaker consists of a sub and a tweeter, connected together by a bipolar capacitor. The circuit gets fed by a copper cable from my amplifier.

I've checked the copper cable ends, but I don't see any oxidization.

When I tap the cone, there's a lot of friction, whereas the cone of the other (good) speaker feels very smooth and reacts to my tap. I notice a very big difference between the two.

Does anyone have an idea what I should be looking for and what the cause might be?

\$\endgroup\$
  • 1
    \$\begingroup\$ Likely the (assumed) paper cone in one has lost its "stiffness" and now rattles. I don't know of a good repair for that, other than replacing the cone which isn't usually "easy." \$\endgroup\$ – jonk Jun 15 at 21:28
  • 1
    \$\begingroup\$ does the speaker cone move freely when (GENTLY) moved by hand? Or do you feel some friction? \$\endgroup\$ – Luke Gary Jun 15 at 21:32
  • \$\begingroup\$ When I tap the cone, there's a lot of friction, whereas the cone of the other (good) speaker feels very smooth and reacts to my tap. I notice a very big difference between the two \$\endgroup\$ – Timon de Groot Jun 15 at 21:43
  • 1
    \$\begingroup\$ Ok, good add that info. It was not apparent from the audio file, where I only heard noise, no music vs noise. Good luck, I think you are on the right track. \$\endgroup\$ – P2000 Jun 15 at 21:48
  • \$\begingroup\$ Why is it rubbing? Examine the perimeter of the cone for damage, is the cone deformed stress (asymmetrical). \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 15 at 22:02
2
\$\begingroup\$

The cone and/or its suspension (the "spider") has warped, and now the voice coil is rubbing against the magnetic pole pieces. It needs to be replaced, or repaired by a technician who knows what he's doing.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ I concur, Dave was 4 minutes faster \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 15 at 22:00
  • 2
    \$\begingroup\$ A very common problem for old speakers. The cardboard cones can rot, or the voice coil gets burnt a bit. Best that a professional speaker repair shop do this, as it takes some skill and nasty solvents and special glues. Most any city/town should have 1 or more repair shops. \$\endgroup\$ – user105652 Jun 16 at 0:57
  • \$\begingroup\$ That's good to know, now I know what's damaged and needs to be repaired. Though I'm not sure if it's worth the reparation cost, since it wasn't a very expensive speaker. \$\endgroup\$ – Timon de Groot Jun 16 at 5:58
  • \$\begingroup\$ You might be able to find a replacement driver on EBay for a reasonable price. I have an old speaker system that I'm doing this for, and I was able to find the exact part number. \$\endgroup\$ – Dave Tweed Jun 16 at 11:21
  • \$\begingroup\$ Perhaps the "bad speaker" was abused electrically. As @Sparky256 has suggested, the voice coil can overheat, and separate from the cardboard cylinder on which it is wound. The loose windings scrape against the magnet. Very difficult to repair, since the voice coil is buried in the magnet - the mechanical tolerances of the gaps are very small. The "push-and-listen" for scraping is a good test. I'd scrap it. \$\endgroup\$ – glen_geek Jun 16 at 12:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.