Yikes, I think I Blew my Cab!

[Tajue17]

I have an ampeg 1X15 and last nite the thing wasn't working at all, I took the plate off the back and reached into the box and everything felt connected okay so I'm wondering can a speaker just die and not work at all with no sound?

as far as I can tell theres no circuits in there just straight wires from the jacks to the 14" speaker. and I tried a different cab from that channel with the same speaker cord and it works fine... I've heard blown ones in the past and it was always clipping sounds or damaged cone sounding stuff

the warranty was up on this in July 05 so if it is blown what is a decent replacement for it and wheres the best place to get it?

thanks for any info. Taj

 

[strummer]

I have an ampeg 1X15 and last nite the thing wasn't working at all, I took the plate off the back and reached into the box and everything felt connected okay so I'm wondering can a speaker just die and not work at all with no sound?

as far as I can tell theres no circuits in there just straight wires from the jacks to the 14" speaker. and I tried a different cab from that channel with the same speaker cord and it works fine... I've heard blown ones in the past and it was always clipping sounds or damaged cone sounding stuff

the warranty was up on this in July 05 so if it is blown what is a decent replacement for it and wheres the best place to get it?

thanks for any info. Taj

A "blown speaker" is in most cases either a melted voice coil (actually the coating on the voice coil that has melted meaning there is a short) or a defective voice coil foremr (happens if the back of the voice coil hits the back plate hard, in which case the voice can get mechanically stuck in the gap)

Measure DC resistance on the input jack, and if it reads +-20% of nominal impedace the voice coil is fine. If not it's broken.

You don't need to replace the speaker, a recone is much less expensive.

 

[Aussie Mark]

Let's play CSI. What's the RMS rating of the cabinet, and what head were you driving it with?

 

[radiotrib]

and how square was the waveform you were feeding it at the time ??

 

[bovinehost]

What is your favorite color?

 

[shamus63]

My head hurts.

 

[tadawson]

What is your favorite color?

Red . . . . . , no . . . . blue!!!! Whaaaaaaaaaa . . . . . . . (flies off cliff . . . . .)

Name that reference!

- Tim

 

[arrowheadguitar]

Monty Python and the Holy Grail

 

[PatAttack]

It's only a model

 

[shamus63]

It's only a model

I promised Jack I wouldn't use any more Pythonisms.

Now biting my tongue...

 

[maddog]

I promised Jack I wouldn't use any more Pythonisms.

Now biting my tongue...

PM them to me, I'll post them for you and Jack won't be the wiser.

 

[shamus63]

PM them to me, I'll post them for you and Jack won't be the wiser.

...the All-Knowing One?

 

[Aussie Mark]

I've told you once.

 

[strummer]

and how square was the waveform you were feeding it at the time ??

Wave form has nothing to do with blowing up speakers, apart from the double power (vs. sine) you are feeding them.

 

[Aussie Mark]

Wave form has nothing to do with blowing up speakers, apart from the double power (vs. sine) you are feeding them.

If you clip your amp and send a square wave to the cab you can easily fry the voice coil. Hence, that's why it's far safer to use a higher powered amp than the RMS rating of your cab.

Young kids in punk and metal bands using bass rigs that don't have enough headroom to compete with drums and two Marshall stacks often fry their speakers by diming their amp in a desperate attempt to hear themselves. It's probably the most common reason for people "blowing speakers".

 

[maddog]

I've told you once.

No you haven't.

 

[maddog]

If you clip your amp and send a square wave to the cab you can easily fry the voice coil. Hence, that's why it's far safer to use a higher powered amp than the RMS rating of your cab.

Young kids in punk and metal bands using bass rigs that don't have enough headroom to compete with drums and two Marshall stacks often fry their speakers by diming their amp in a desperate attempt to hear themselves. It's probably the most common reason for people "blowing speakers".

Si. From my speaker building days, never have blown a woofer but tweeters, a big hearty YES! DC forces the voice coil to one of the travel extremes. All that current with no place for the heat to go. Usually happens in tweeters because the magnet wire is very small gauge. As I said earlier, never saw it in a woofer but then again, I was never running that much power before (maybe 2-10W).

 

[shamus63]

You know, posts #15 and 17 prove to me that you're never too old to learn something new.

I always figured it was safer to keep your bass head power rating even or somewhat below the cabinet ratings...to the layman, that would make sense.

Now I have incentive to upgrade from my B2R!

 

[maddog]

Now I have incentive to trade up on my Ampeg B2R to an SVT-PRO!

Do It! Do It!

 

[Aussie Mark]

I always figured it was safer to keep your bass head power rating even or somewhat below the cabinet ratings...to the layman, that would make sense.

Rule of thumb for a PA or bass rig is to use a head or power amp that is rated 1.5-2x the RMS rating of the cab it's driving. That way, you have headroom to spare, and should never run the risk of clipping your amp and sending a square signal to the cabinet.