First Signs That JBL D120F is Going South?

[skydog45]

If the speaker looks fine physically, what are some things to listen for to determine the speaker is ok audio wise?

I've just bought a couple JBL D120F's for my guitar amplifiers, and there is a very faint but noticable sound like a light bulb that's gone bad. You know when you shake it?

It doesn't get too loud when cranked and the tone of the speakers is great.

Thanks. I'm a newbie and would like some guidelines for buying used JBL's.

[GordonW]

:( Sounds like the voice coil winding is starting to de-laminate. First step toward what we, in the reconing industry, call a "slinky"... the windings all seperate, and start flopping around...

Regards,
Gordon.

[skydog45]

:( Sounds like the voice coil winding is starting to de-laminate. First step toward what we, in the reconing industry, call a "slinky"... the windings all seperate, and start flopping around...

Regards,
Gordon.

Thanks for your reply Gordon.

Only seems to happen after the note has been struck...while sustaining. Maybe it's just a vibration of the amp?

[edgewound]

Thanks for your reply Gordon.

Only seems to happen after the note has been struck...while sustaining. Maybe it's just a vibration of the amp?

If the noise happens while the speaker is in the amp, maybe you have a tube going bad. Take the speaker out of the amp to test it thoroughly.