Blown speaker

[guidoilieff]

Hi. I have an Ashdown MAG C115-300 EVO III http://ashdownmusic.com/products/1/Bass-Amplification/18/Legacy/33/MAG-C115300-EVO-III-/

The speaker coil broke 2 times using a passive bass with no stompbox.


Is it probable that the amp is burning the speaker or just a bad speaker?
Is there a way to test if the amp is sending too much power to the speaker?

thanks

[wavley]

Are you using a lot of that sub harmonic generator built into that amp?  I believe that a speaker in a combo should be chosen to handle everything that the amp is designed to throw at it, but that isn't always the case.

Check your amp's output for DC offset, speakers really don't like DC.

[PRR]

300 watts is a LOT for any single speaker. Especially on stage where loudness is constantly high.

I'd match that amp with four high-power 15" speakers such as E-V EVM15B (I don't think they are still in production).

Complain to the company. I agree with wavley, a combo "should" work-together, yet this one seems to have a problem with that.

[guidoilieff]

Are you using a lot of that sub harmonic generator built into that amp?  I believe that a speaker in a combo should be chosen to handle everything that the amp is designed to throw at it, but that isn't always the case.

Check your amp's output for DC offset, speakers really don't like DC.

Thanks, I will.

I wasn't using the sub harmonics both times

[guidoilieff]

300 watts is a LOT for any single speaker. Especially on stage where loudness is constantly high.

I'd match that amp with four high-power 15" speakers such as E-V EVM15B (I don't think they are still in production).

Complain to the company. I agree with wavley, a combo "should" work-together, yet this one seems to have a problem with that.

The combo is 150w. You can add an extra 15' speaker to get 300w.

I'm thinking more about a production error and not that much about an engineering problem. I didn't find people complaining about blown ashdown speakers.

[Gus]

As wavley posted check for DC at the speaker.
Does the combo make a pop noise at turn on?

[guidoilieff]

As wavley posted check for DC at the speaker.
Does the combo make a pop noise at turn on?

It does a little bit.

The way to test is to grab a dmm and select, lets say, 20v dc and see if there are any volts present in the speaker output when is turned on? Is there any risk of blowing the poweramp?

thanks

[wavley]

As wavley posted check for DC at the speaker.
Does the combo make a pop noise at turn on?

It does a little bit.

The way to test is to grab a dmm and select, lets say, 20v dc and see if there are any volts present in the speaker output when is turned on? Is there any risk of blowing the poweramp?

thanks

You should really have less than 50mV of DC on your output, any more than that and you're looking at bad things for speakers and it's telling you that your amp isn't biased correctly.  Ideally you want to get this number as close to 0VDC as possible.