How to tell if speakers are blown

[stevo1210]

I've got a set of very, very expensive Bose Companion 5 computer speakers. Basically someone decided to turn the volume up all the way while the system was off (might be someone cleaning and accidentally turned the knob while cleaning). Anyway, I innocently went into itunes, and I nearly fell off my chair at the loudness of the music!
I immediately turned them down to minimum. Then immediately got a torch and peered through the metal grille and I can't see any rips or the like in the tweeters or the woofer. I'm playing music as we speak and it seems to be playing okay, treble and bass is per usual. Nice smooth sound even at a higher range volume.
These speakers are connected to the computer by USB, not the regular 3.5mm jack.
Now what I want to know is... are they blown in any way? They are under warranty but I'd still like to know how I can detect a blown speaker.

[stevo1210]

Re: How to tell if speakers are blown

Also found this in a manual from Bose for the Companion 5's...

"The system output maybe reduced by an internal protection feature if you play music at full volume for a long period of time."

Does that mean you can't blow the speakers?

[Th3_uN1Qu3]

Re: How to tell if speakers are blown

Does that mean you can't blow the speakers?

They've got a built-in compressor/limiter. You can still blow them up but you really have to try.

Btw, Bose stuff nowadays is 99% marketing, 1% research. They are ridiculously overpriced for what's in there. Don't take them apart unless you want to have a heart attack.

[alan monro]

Re: How to tell if speakers are blown

If the speakers sound OK they are OK , the ears are the final judge .
All speakers are designed to take overloads for short times .
You bugger them if they are overloaded for a long time or consistently...........................Alan

[larrymoencurly]

Re: How to tell if speakers are blown

Btw, Bose stuff nowadays is 99% marketing, 1% research. They are ridiculously overpriced for what's in there. Don't take them apart unless you want to have a heart attack.

A friend of mine had a Bose clock radio that blew its power transformer. I don't know if it has a thermal fuse inside or actually burned out windings, but it uses flat ribbon wire, a replacement was over $70 from some Ebay source, and Bose wouldn't reveal what the outputs were supposed to be.

I think it's possible to damage a speaker from too much power without causing visible damage to the cone or suspension but just warp the voice coil so it scraps in the magnet gap.

[Th3_uN1Qu3]

Re: How to tell if speakers are blown

I think it's possible to damage a speaker from too much power without causing visible damage to the cone or suspension but just warp the voice coil so it scraps in the magnet gap.

But then it would definitely sound bad, which seems not to be the case here, fortunately.

[momaka]

Re: How to tell if speakers are blown

I once forgot to turn down the volume in Windows after using it with my external speakers and the computer I did this with has a Yamaha YMF724 PCI sound card that has a TDA1517 amp IC (capable of 6W/channel). I don't know if my Sony MDR-023 headphones took any damage, but my ear drums sure did! I kid you not, I nearly fell off my chair. Those headphones still work fine to this day and I still use them regularly.

I've also seen many YouTube videos where people try to blow speakers up. Most will take quite a while before they go out (granted it's not one of those let's plug some speakers in the wall socket and see what happens videos).

[lti]

Re: How to tell if speakers are blown

The amplifier in my Cyber Acoustics MMS-20 speakers can blow speakers easily. It only uses a TEA2025B amplifier, but the bass boost is too much for my $10 Philips headphones. Those headphones sound like larger and more expensive headphones when they are connected to that amp... until they start buzzing.

For some reason, that amp only boosts the bass on one channel if the coupling caps between the tone control circuit and the TEA2025B aren't perfectly matched. It is hard to hear the difference in headphones, but it is easy to tell the difference through the speakers.

Speakers won't blow after only a few seconds unless the amplifier is rated for many times more power than the speakers.