How to figure out if the speaker is blown

How to figure out if the speaker is blown

Can someone tell me some signs of blown speakers? Since i got my subs my sound is not very clear. Could it be because one of the speakers is blown?

I suggest you turn the sub down or off and then listen. If a speaker is blown there will be obvious buzzing or distortion from the suspected speaker or no sound at all. Use the fade & left/right controls to listen to each speaker seperately. Another thought is that the sub is just turned up too high and overriding the other speakers.

Another thing I notice in my car, is that the subs actuall interfere with the operation of the rear speakers. They create so much pressure in the trunk, that they actually push on the backs of my my 6x9 cones. I'm thinking about getting some baffles from crutchfield to help alleviate this.

I just leave the back seats down. That seems to help both the sound of the 6x9's and my 2 12's drastically. The pressure inside the cab while the seats are down is unreal!!! Although the baffles would, without doubt, get rid of the problem.

if u leave seats down.....

If you leave the seats down.....do u have to take the headrests out and move the seat belts?????? I've thought about doing that but my seats are laid back and it looks like i would have to remove the headrests(no big deal......but what about the seat belt straps?????

DJShoOk 1

blown speaker

The only true way to determine if the speaker is blown is to use a digital multimeter and determine the impedance of the speaker. Set the multimeter on "ohms/impedance" (greek letter Omega). The speaker should read out at 4 ohms. Many people confuse blown speakers with excessive volume levels.

Re: How to figure out if the speaker is blown

I am almost 100% sure this is a settings problem, especially if your subs are brand new.

1. Did you use your HU's preouts?
2. Is your LOUD button ON?
3. Is your BASS setting all the way UP?
4. Did you set your GAIN all the way UP? (in the amp)

Most of the time, here's the most likely scenario: The user would crank up the volume (in the HU) to get more output from the subs, but since the HU is powering their mids/highs, it's distorting them as well while the amp gain is turned all the way down and the user would keep on cranking it up and distort the speakers, not knowing that it's in the amplifier setting. You might wanna check this first.

You just need to tweak your system. Good luck, and let us know how it turns out! :mrgreen:

Multimeter for 4 ohms, next you can place a dry 1.5Volt C cell battery across the speaker if it my a noise then it working.
Cheers Drew

That's partly correct...putting 1.5V across the coil will tell you if the coil is open or not. But, it won't tell you what (most) people refer to as "blown". A coil can be not blown open, meaning the speaker will thump when you put a voltage across it, but that will not tell you if the voice coil assembly has been mechanically displaced or distorted. That's the usual result of "blowing" a speaker. Too much heat will distort the coil form, over-extending it will wreck either the surround that holds it aligned in the gap, or tear the connection of the coil form to the speaker cone, or both. Results is the buzzing sound when it tries to follow the musical sine-wave.

And remember, it is NEVER a good idea to put a DC voltage (what a battery is) across a speaker's coil! DC voltage is the by far most responsible for blowing a speaker...when the amplifier is pushed beyond it's capability, the waveform "clips", meaning the peaks are "clipped" off. Where it's clipped, it's DC voltage! That's why more speakers are fried with low-power, low-headroom amplifiers than a good amp supplying too much current.

Re: How to figure out if the speaker is blown

I agree on this one.

It is true that initially excessive heat build up will cause physical distortions in the voice coil, but these distortions increase mechanical friction which reduces speaker impedance, which in turn causes more heat build up, which generally leads to the voice coil blowing open.

Using a 1.5 volt battery to test a speaker will not do any harm, unless it's a really cheap speaker and you connect and disconnect the battery over and over. A 4 ohm speaker rated at 50 Watts is designed to handle 14.14 volts RMS (20 volts peak) continuously.

DC voltage is generally not a problem for speakers either, unless you exceed the peak voltage for the speaker for an extended period of time. The issue with amplifiers clipping is that at the point when clipping is reached, there is a very sudden (but brief) increase in the odd harmonic content of the signal. If you play a sine wave at 10 kHz and drive the amplifier into clipping, you will get significant signals out of the amplifier at 30 kHz, 50 kHz, 70 kHz, etc. That's the downside of transistors. As soon as they reach the cutoff point, all hell breaks loose. These odd harmonics can kill tweeters in no time.

Oxy, I was trying to make the point that when 99% of people say their speaker is "blown", they're referring to a buzzing or other not-normal sound coming from it. If the voice coil is blown open, it will make no noise at all (barring of couse multi-driver setups, where the mid or tweet may still make some noise).

In the worst case, the scenario you described (the runaway heat / distortion / heat cycle), I've actually torn apart speakers who's coils show continuity, but do not function as any speaker you'd want to play music on, and found the coil distorted so much it actually rubbed thru the shellac insulation! With the incredibly tight tolerances manufacturers are using now, wouldn't be surprised if that happens often. The speaker would make noise, but I wouldn't call it sound...

Didn't say using a 1.5V battery would do any harm. Said it's not a good idea to put DC in a speaker. You said yourself "14 watts RMS" RMS is a term used for AC voltage, not DC. Apples and oranges. When DC is applied to a speaker, the coil is forced to one end of it's travel, sometimes bottomed out. Not good.

The harmonics you refer to are caused by transistor riniging at the leading and trailing edges where the sine wave goes into clipping...I over-simplified, your description is better.

You're 1000% right about those harmonics killing tweets in short time. The caps used to keep the lows out of them will let freqs that high thru with no problem.

Ah. We're converging. Just one point. RMS applies to both DC and AC.

If you have a 10 volt peak to peak sine wave, the peak is obviously 10 volts. The RMS voltage is 10 divided by the the square root of 2 - 7.07 volts.

With a 10 volt DC battery, the peak voltage again would be 10 volts and the RMS voltage would also be 10 volts.

In the end, I'd be willing to bet his speakers are just fine (assuming they've survived the abuse) and he's just got his gains set incorrectly.

RMS is the equivilancy of a DC voltage in a AC signal....so I guess you could say 10V RMS DC, but why would you?

I've seen quite a few cases where a DIY-er didn't set the input sensitivity on thier amp correctly to match the preamp putput.. Makes for some head-scratching, something like "my speakers must be blown, I don't even have to turn it up loud and they buzz" ("loud" referring to the volume level on the HU).

Overdriving the amp inputs. Not sure why car audio manufacturers haven't standardized on RIAA input and output levels, like the home industry (more or less) did. I've seen 4 volt outputs on a HU! Unless you're planning on running it thru 200 foot long RCAs, why? Seems to me like they assume people think "if 2 volts is good, 4 volts must be TWICE as good!". Instant overdriven amp.

Agree with you....speakers are probably fine, rest of sys needs to be set up correctly.

lmfao. you guys are making it harder than it is. All you have to do is take out the speaker in question from the car and connect it to a "normal" functioning system. Is it working fine now? Still distorted? Easy as that.

Now as far as the "1.5v" testing-- Any driver WILL react to any input voltage--but that doesn't necessarily mean that it is not blown. Heck even blown coils can sometimes still play music...when their coils are partially burnt. Go figure :roll:

1.5v battery on a Stroker 18D2 please... uh the 18-incher doesn't "move", it must be blown! lmfao :roll:

lmfao. you guys are making it harder than it is. All you have to do is take out the speaker in question from the car and connect it to a "normal" functioning system. Is it working fine now? Still distorted? Easy as that.

Ok, he moved it. It sounds distorted. Time to go buy a new one! LET'S COOK THAT ONE TOO, SINCE PEOPLE WHO ARE TRYING TO HELP HIM ARE MAKING IT HARDER THAN IT HAS TO BE! Oh, wait, it sounds fine! DARN! WISH SOMEONE WOULD EXPLAIN WHAT COULD BE WRONG IN MY SYSTEM (maybe even make it harder than it has to be?).

Now as far as the "1.5v" testing-- Any driver WILL react to any input voltage--but that doesn't necessarily mean that it is not blown. Heck even blown coils can sometimes still play music...when their coils are partially burnt. Go figure

What say Oxy...ever seen a "partially" blown coil? I can imagine one scenario..there's a microscopic break in the wire, and someone is trying to put enough juice into it, to make it arc...

1.5v battery on a Stroker 18D2 please... uh the 18-incher doesn't "move", it must be blown! lmfao

It won't move far enough to see, most likely. But it will make "scratching" noises as it's energized / de-energized. Unless it's blown open.

Except if it's partially blown open... :shock:
_________________

Some people like to keep things simple. This has two distinct advantages (partially

1 - troubleshooting takes a lot less time, and
2 - you get lots of experience fixing the same problem over and over...

Now back to the original problem. Has it been resolved? What is the system setup? Stock HU and stock speakers with a sub, or something else?