Can You Physically See If You Have a Blown Speaker?

[rodak]

There are two different kinds of "blown" - one in which the speaker makes no sound at all (that's what the battery test will reveal - or just plug in and play and if it makes sound, then it's not "completely" blown) and the other where the speaker "works", i.e., it makes sound, but the sound is bad, particularly when driven to normal playing levels. This usually means the voice coil has warped due to excessive heat or mechanical excursion(i.e., it tried to move farther than it was able). With this kind of failure, you can usually tell by gently pushing the cone in and out and if it makes a scratchy sound, it's blown. Normally doing this should be totally silent.

What does it sound like when you play through it? Usually a warped voice coil will sound like crap, like real bad scratchy/crackly sounds.

I don't think I've ever seen a speaker blown so bad that you could see physical damage to the cone - you'd have to hit REALLY it hard to do that, I would think.

I'm sure there are fine points I've missed here, and someone will be along to correct, but these are the main situations I've run into. I'm not sure if pushing the speaker cone to test it is a recommended thing to do, but I've never damaged a good speaker by doing so.

 

[AGCurry]

A rather unsophisticated, old-school method was to gently press the cone in from the front while listening and feeling for contact between the voice coil and magnet structure, said contact being a bad sign. This method will not necessarily tell you of mechanical fatigue or continuity failures.

 

[6thplanet]

If you see anything like this, probably a good indication something isn't right.

 

[baxter_x]

Some pictures of this thread are painful to look at......

 

[DJ Bebop]

Can You Physically See If You Have a Blown Speaker?

Sometimes...

 

[60bass]

if it looks like my avatar..... then yes!

 

[bassliner50]

Visual evaluation very clear in this case.

 

[S-Bigbottom]

Plug a 1/4" cable in your cab, and touch a 9v battery to it. The bad speaker will suck in,

If a speaker sucks in just turn the battery around and the speaker will push out.

 

[Wesley R]

I put a voice coil (or at least some of the windings) through the cone, and yep my ignorance was visible.

I was told that heat would crack the magnets on Altec 421A's. That would be visible. My guess is urban myth.

 

[agedhorse]

I put a voice coil (or at least some of the windings) through the cone, and yep my ignorance was visible.

I was told that heat would crack the magnets on Altec 421A's. That would be visible. My guess is urban myth.

Yes, urban myth.

 

[Rick_Bass]

I love the innuendo in the thread --- put it this way -- I worked and I AM Working on F35 Jet fighters.... I can gab and talk and throw you a million machinating comments ... I wont -

 

[Rick_Bass]

we are all good and great at what we do

 

[Mike Caldwell]

I think this one has some visible damage.......the result of the system with no high pass filtering, no limiting and wanting six of those to sound like an NFL football stadium.

 

[Smallmouth_Bass]

So I pulled out the combo amp in question and played it this evening at the same settings I had it at the gig and it sounded just fine. There must have been something else going on. I think it's because I put myself in the mains a little that a feed was taken from for a stage monitor (a 15" at that! - bigger than the mains). I think there may have been something weird going on with that whole setup.

 

[JeezyMcNuggles]

If a speaker sucks in just turn the battery around and the speaker will push out.

And the others will push out in that case. Problem still detected.

Tip +
sleeve -

 

[cheapbasslovin]

So I pulled out the combo amp in question and played it this evening at the same settings I had it at the gig and it sounded just fine. There must have been something else going on. I think it's because I put myself in the mains a little that a feed was taken from for a stage monitor (a 15" at that! - bigger than the mains). I think there may have been something weird going on with that whole setup.

You said you ran bass to the mains and that your friends said the mains sounded distorted? How likely is it that you kill the tweeter on your combo so you aren't used to hearing the distortion or other harmonics on the high end of your signal, and that the mains had no problem recreating those tones?

 

[lokikallas]

If you push gently on the cone with fingers, a speaker should move in and out with the resistance of the magnet. If you feel or hear a scraping noise, the voice coil is unwound a bit and needs repair. If it's frozen solid, it's also bad lol. I generally push with my fingers in a circle as wide as I can around the dust cap.

 

[agedhorse]

I love the innuendo in the thread --- put it this way -- I worked and I AM Working on F35 Jet fighters.... I can gab and talk and throw you a million machinating comments ... I wont -

My future son in law works on C5's and 141's, the other end of the aircraft spectrum

So I pulled out the combo amp in question and played it this evening at the same settings I had it at the gig and it sounded just fine. There must have been something else going on. I think it's because I put myself in the mains a little that a feed was taken from for a stage monitor (a 15" at that! - bigger than the mains). I think there may have been something weird going on with that whole setup.

This is why it's really important to do good troubleshooting. Be sure that what you think is happening really is happening.

And the others will push out in that case. Problem still detected.

Tip +
sleeve -

Since the cabinet is a 112, none of this makes any sense.

If you push gently on the cone with fingers, a speaker should move in and out with the resistance of the magnet. If you feel or hear a scraping noise, the voice coil is unwound a bit and needs repair. If it's frozen solid, it's also bad lol. I generally push with my fingers in a circle as wide as I can around the dust cap.

There is no resistance from the magnet (magnetic field) unless the driver terminals are shorted together. The resistance you feel open circuit is purely mechanical due to the compliance of the suspension components.

 

[Smallmouth_Bass]

You said you ran bass to the mains and that your friends said the mains sounded distorted? How likely is it that you kill the tweeter on your combo so you aren't used to hearing the distortion or other harmonics on the high end of your signal, and that the mains had no problem recreating those tones?

Yes, sorry. The mains distorted issue and my bass sounding different were two different problems on two different gigs.

 

[Redbrangus]

And the others will push out in that case. Problem still detected.

Tip +
sleeve -

In the battery test, ANY movement of the cone, either forward or backward is an indication of a functional voice coil. It's most definitely not 'one way good, the other way bad.'

And my experience is that the majority of speaker failures are from burned out voice coils and show no visible signs of failure.