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Scratchy Speaker [message #88841] Wed, 19 September 2018 04:17 Go to next message
Junior is currently offline  Junior
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Registered: July 2018
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My computer speaker, which is an old speaker, sounds scratchy. I know I just need to buy a new one. What I'd like to know is if I can still fix the speaker on my own. I would like to learn how to fix things like the speaker.
Re: Scratchy Speaker [message #88842 is a reply to message #88841] Wed, 19 September 2018 08:31 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17402
Registered: January 2001
Illuminati (33rd Degree)

That usually means the driver's voice coil has overheated and unwound, so it is rubbing. Most people just call that a "blown speaker" because it happens after it has overpowered for a while. You'll need to replace the driver.

As an aside, there are two common failure modes for a speaker driver: Thermal and Mechanical.

When a driver is overpowered with mostly medium and high frequency content, then the heat from the current through the voice coil causes the temperature of the motor core to rise above the limits of the adhesive that holds the coil on the former. Eventially, the glue melts and the coil unwinds. It then begins to buzz, and often stays this way until the speaker is repaired or replaced. Sometimes the loose winding catches on the center pole and tears or rubs through and create an open circuit, in which case the speaker won't make any sound any more.

When a driver is overpowered with mostly low frequency content, it may exceed its mechanical limits. The voice coil bobbin can strike the back plate or the suspension can tear. In either case, the speaker will "complain loudly" with impact sounds.

Less common failure modes are fusing, contact damage and environmental exposure. Fusing happens when a large high-current spike melts the voice coil. This is usually the result of an amplifier failure or misconnection. Contact damage happens when something strikes the diaphragm and dents or penetrates it. And exposure is when the diaphragm gets wet or has UV damage from the sun. I've seen cones so sunbaked that they fade to white and eventually become so dry and brittle they crack and nearly turn to dust when touched. Sometimes introducing a dry cone to a humid environment will help - That's something I've done to old tube radios to restore life to their speaker cones.

Re: Scratchy Speaker [message #88844 is a reply to message #88841] Wed, 19 September 2018 11:30 Go to previous messageGo to next message
sawyer25 is currently offline  sawyer25
Messages: 140
Registered: July 2016
Master
I wouldn't dare to try and open up a speaker if it ever developed any problem (irrespective of the extent) because the last time I did this, the speaker got spoilt completely. It is much better to have a tech-savvy person fix it for you.
Re: Scratchy Speaker [message #88855 is a reply to message #88841] Thu, 20 September 2018 23:38 Go to previous messageGo to next message
Malfoy is currently offline  Malfoy
Messages: 79
Registered: June 2018
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This problem solving would be a nice project. I don't want to destroy my speaker as it is still okay for me. If this happens to my speaker then I will try to tinker with it. It will go to the dump anyway, so I won't worry in breaking it.

Do all speakers have a similar setup?
Re: Scratchy Speaker [message #88935 is a reply to message #88841] Fri, 05 October 2018 04:04 Go to previous messageGo to next message
Junior is currently offline  Junior
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Registered: July 2018
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So this means that the speaker is going to a normal "wear and tear" process. Does it also mean that even when we are setting a moderate volume that the speaker will eventually become scratchy?
Re: Scratchy Speaker [message #88939 is a reply to message #88935] Fri, 05 October 2018 09:38 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17402
Registered: January 2001
Illuminati (33rd Degree)

No, voice coil unwinding isn't normal wear and tear. In most cases, it will never happen. I have some old radios with speakers that are nearly 100 years old and they still work fine.

When a speaker is overheated due to excessive power levels for a period of time, the adhesive that glues the winding to the bobbin begins to fail and the coil unwinds. This is failure mode that is caused by overdriving the speaker.

As long as you don't overdrive the speaker, the voice coil will stay intact for decades.

Re: Scratchy Speaker [message #88966 is a reply to message #88841] Tue, 09 October 2018 11:33 Go to previous messageGo to next message
Malfoy is currently offline  Malfoy
Messages: 79
Registered: June 2018
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My father always tells me that older equipment lasts longer compared to newer counterparts. That may be the reason for the old radio maintaining a good sound or what you just explained. I go for both.

How about speakers that were exposed to hot and humid weather? Does the humid climate affect the speaker as overdriving it?
Re: Scratchy Speaker [message #88971 is a reply to message #88966] Tue, 09 October 2018 13:50 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17402
Registered: January 2001
Illuminati (33rd Degree)

Ambient temperature has no effect on voice coil overheating. The temperatures inside the motor core get hot enough to cook before the adhesive begins to fail.

Re: Scratchy Speaker [message #88979 is a reply to message #88841] Wed, 10 October 2018 00:07 Go to previous messageGo to next message
sawyer25 is currently offline  sawyer25
Messages: 140
Registered: July 2016
Master
Just by reading Wayne's comments, this looks like one of those things that you had better let a technician fix. I have had a certain speaker for 10 years and it has never developed any problem so I guess it depends on how they are handled.
Re: Scratchy Speaker [message #88993 is a reply to message #88841] Wed, 10 October 2018 17:17 Go to previous messageGo to previous message
Junior is currently offline  Junior
Messages: 69
Registered: July 2018
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So an update on my project, I made the problem worse because there is no more sound. I'm not sure whether I shorted or disconnected something. What I get from this is experience, and I learned from Wayne's comments.
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