Anybody know a good way to test if there is a blown speaker ...

Anybody know a good way to test if there is a blown speaker in a Marshall 4x12? Am plugging straight into a jcm 900 head and when I play at low volumes, everything seems fine, but when its cranked and i palm mute, I get a slight flapping sound as if one or more of the spekers are blown or damaged. Is there a safe way to check each speaker individually besides just listening? thanks

I'm thinking outside the box here but if someone could hold a flashlight behind the speaker while you play through it maybe you can find a hole ?
Might be cheaper to repair the cone than replace it.
leftybob

Most Of The 4x12 Cabinets Ive Owned
All Have Given Me Some Problems ( Why ? )

Loud Excessive Volumes Loosen Connections
Causeing Fadeouts / Rattleing Of The Spekers
Tightening Nuts Even Loose Handels / Jacks
And Even Cracking Or Braking Off
Of The Wire Connecting Points

But The Major Of It All
Would Be The Heavey Bass Frequenices
Heavy Duty Speakers Help Here

Overloading The Amp
As You Know Now That Excessive Loudness
Causes Great Strains On Speakers
Everytime You Crank The Amp

If You Picked It Up Used Then You May Already Know Why Someone Got Rid Of it

Hope This Helps

Usually, if you push your finger tips against the speakers outer cone, the paper should move in and out we light presure. If the speaker paper resist, and it feels real tight, this means the speaker needs re-coning or replacing.
Robb