Blown speaker

[Baum83]

Hey guys,
I need your advice on this little issue I have...
We had a gig yesterday, and during soundcheck the soundguy came up to me and told me that one of the Vintage30s in my 4x12 is apparently fucked.
Now I'd like to replace the damn thing, but how do I know how many Ohms the replacement speaker should have? It's a Marshall 1960BV, operates with 4 or 16 Ohm in mono or 8 Ohm in stereo.
I assume that the cab still has the same amount of Ohms, even if the speaker is busted - it's still there and "resisting", or am I wrong there?

[Black Mariah]

Re: Blown speaker

The speaker should say on its side how many ohms it is. Just read that. [img]images/icons/grin.gif[/img]

Yes, the cab still has the same about of ohms if the speaker is busted. At least as far as I know...

Here's a question. Can you tell that the speaker is fucked up, or is it something only the sound guy can hear when he has a microphone soloed on that one speaker? If it's not bugging you, I'd roll with it for now.

[Baum83]

Re: Blown speaker

Duh. I should sober out before posting. I won't touch any tools as of now, though. Thanks for the hint. [img]images/icons/grin.gif[/img]

The sound guy noticed it when he miked that speaker and it didn't behave like it should have. The cab doesn't sound bad in any way, though, so as long as I won't fry any of my other equipment I'm fine with the remaining ones. 3 speakers still produce enough noise, and I guess there's always a Vintage 30 or two floating around on ebay.
btw, the EMGs have yet to arrive, I guess they'll be in on Tuesday, else I'll have to kick someone's ass at the post office. [img]images/icons/smile.gif[/img]

[MountainDog]

Re: Blown speaker

BM is correct, the speaker should have a label saying how many ohms it is. Also, you can use a multi-meter (like from Radio Shack) to measure the ohms of the speaker (same way you measure ohms of a pickup).

By the way, for your cabinet to have the 4ohm mono or 16 ohm mono or 8ohm stereo options, your speakers in there are all 16 ohm.

The bad speaker could be not sounding good for a variety of reasons, torn surround, torn cone, dome falling off, coil rubbing, etc. I recommend changing it out soon. If the damaged area causes the voice coil to rub and short out, your amp will NOT be happy. Suggest looking at the speaker and find out if you can see any obvious defects (like a tear somewhere). You can do a temporary fix on a tear with crazy glue until you can get another speaker.

[Black Mariah]

Re: Blown speaker

They'd better be there soon or I will rain hellfire and seas of blood down upon the USPS. [img]graemlins/laugh.gif[/img]

[Baum83]

Re: Blown speaker

Originally posted by MountainDog:
By the way, for your cabinet to have the 4ohm mono or 16 ohm mono or 8ohm stereo options, your speakers in there are all 16 ohm.

The bad speaker could be not sounding good for a variety of reasons, torn surround, torn cone, dome falling off, coil rubbing, etc. I recommend changing it out soon. If the damaged area causes the voice coil to rub and short out, your amp will NOT be happy. Suggest looking at the speaker and find out if you can see any obvious defects (like a tear somewhere). You can do a temporary fix on a tear with crazy glue until you can get another speaker.

<font size="2" face="Verdana, Helvetica, sans-serif">Cool, thanks for pointing all that stuff out. [img]graemlins/toast.gif[/img]
Next time I'm at our rehearsal space I'll take a closer look at it, the last thing I want to happen is my beloved Marshall going up in flames.

BM:
Nothing wrong with Sodom&Gomorrha-style punishment [img]images/icons/grin.gif[/img]

[GWARGHOUL]

Re: Blown speaker

On the tear repair...

Crazy glue does not flex well.
I've always used a medium black silicone caulk to repair subwoofers and such. Its strong, and it flexes. I've had the voice coil dome fly off before, and I fixed it with black silicone. Works fine now.

[MountainDog]

Re: Blown speaker

GwarGhoul, thanks for your post. FYI, I mentioned the crazy glue as just a quick emergency fix as I initially didn't want to go into deep speaker construction details and/or list a fix that someone might think would work as permanent, as its always best to replace the speaker.

You are correct on using a flexible black silicone, but only if the tear is on the flexible/moveable surround, which is the part of the cone assembly thats on the very outer diameter and is the part that glues to the frame. As far as the cone itself and the dome itself, you want those very solid and non-flexible, so crazy glue to re-attach the dome or fix a cone tear is preferred. A speaker cone can be thought of as a piston, with the only parts that should move being the suspension, which is comprised of the 'spider' which attaches the coil to the frame and the 'surround' which attaches the cone to the frame. These two parts working together keep the stiff cone/dome assembly moving in and out in a straight line to keep the coil centered in the motor gap. A tear in the surround (or spider) and sometimes even a tear in the cone will disturb the linear movement of the assembly and cause a rocking motion that at best makes the speaker sound bad and at worst could cause the coil to rub and short out...possibly blowing an amp.

So dome or cone issue = crazy glue
Surround issue = flexible black silicone

[JACKSONFREAK]

Re: Blown speaker

An easy way to sdee which speaker is bad aside from the multi-meter is a 9 volt battery. Touch the battery terminals to the speaker terminals and if the voice coil isnt frozen the speaker will click and the cone will move. If the coil is frozen that's your bad speaker. Also if you use the multi-meter and find a bad speaker the readout will bounce around or just increase in number and just look like a wrong reading. Almost like the meter is broken.
Gil