Amp went in to protect, speakers damaged?

[Laurens_B]

Hi all,

I am a bit worried because of the following: I was just watching the first part of Transformers, and at one point my amp just went into protection mode, it shut itself down. At first I wasn't sure what happened, so I played the exact same piece again, and the amp again shut itself down. This time I watched the woofers of my speakers, and they made a huge conus excursion, which probably caused the amp to run out of current and shut down.

The gear involved is B&W 683 S2 speakers, and a Yamaha RX-A2020, nothing else. The amp didn't get really really hot (I've had it hotter before). As I've noticed, in movies, huge conus excursion happen a lot, apparently a lot of very low high amplitude frequencies in movies. Never really caused a problem. However, because this one caused my amp to shut down, I am worried if I might have damaged the speakers. I just ran a frequency sweep (20Hz - 20kHz) and I mentioned nothing out of the ordinary, though this might not be conclusive? Can speakers easily handle this? Anything I should worry about?

First time this happens. These speakers allegedly dip to 3 Ohms at an unknown frequency, which might be at the root of the problem. Any of you guys have experience with this? Or know whether or not my speakers might be damaged?

Thanks!

 

[Anderson]

I think you've answered your own questions.

You ran a test tone sweep and everything sounded okay.

The speakers are allegedly rated down to 3ohms and the amp only went into protection mode when you got to the same part of transformers.

It would appear the speakers are asking too much of the amp? Have you tried the same passage but with the volume reduced to half?

 

[Laurens_B]

I think you've answered your own questions.

You ran a test tone sweep and everything sounded okay.

The speakers are allegedly rated down to 3ohms and the amp only went into protection mode when you got to the same part of transformers.

It would appear the speakers are asking too much of the amp? Have you tried the same passage but with the volume reduced to half?

Thanks for your response. Though should I be aware of these kind of excursions, or do you think speakers can easily handle this?

I did not test it at half volume, thought about it, but I wasn't sure if I could damage either the amp or speakers by repeating it. I might try it tomorrow with a cold amp, see if that makes a difference.

The volume was at -12.5dB by the way. I watched the rest of the movie at -15dB.

 

[davedotco]

I think you've answered your own questions.

You ran a test tone sweep and everything sounded okay.

The speakers are allegedly rated down to 3ohms and the amp only went into protection mode when you got to the same part of transformers.

It would appear the speakers are asking too much of the amp? Have you tried the same passage but with the volume reduced to half?

Thanks for your response. Though should I be aware of these kind of excursions, or do you think speakers can easily handle this?

I did not test it at half volume, thought about it, but I wasn't sure if I could damage either the amp or speakers by repeating it. I might try it tomorrow with a cold amp, see if that makes a difference.

The volume was at -12.5dB by the way. I watched the rest of the movie at -15dB.

First point is to look at the eq and any signel processing being used. There will be a fair amount of sub bass on the movie and if any bass lift is being used, this will increase the sub bass too.

The speakers are ported, so at some point the bass drivers will have no loading on them, this will be an octave below resonance, so quite possible in the sub bass range of the soundtrack and may explain the excessive cone movement.

The other possibility is that the bass power of the soundtrack is too much for the amp/speaker paring, B&Ws have a low impedence at bass frequencies and quite possibly a difficult and varying phase angle. This requires a lot from an amplifier and maybe your reciever is not up to it.

One thing to try though, look through the menus on your unit and see if you can adjust bass rolloff for the main speakers. At the very least you should be able to set them to 'Small' and limit the sub bass in that way.

 

[Pistol Pete1]

Do you use a frequency cut off for the front two speakers? It's suggested/recommended (in above post too) that you set all speakers to small and at a crossover of 80hz.

Set like that, most of your bass will be produced by the sub, thus using it as intended and saving the other speakers in your system.

 

[steve_1979]

Movies have much more low frequency content and dynamic range than music does which makes listening to movies hard work for the amp and speakers. Your speakers will be fine when set to full range for music listening but with movies ideally they're best set to 'small' and cross them over to a subwoofer at 80Hz for handling the bass.

If your speakers sound fine then I doubt you've done any damage but I wouldn't make a habit of playing movies with them set to full range because it's tempting fate if you amp keeps cutting out like that.

If you don't want to add a subwoofer to your system try setting the speakers to small with the crossover/roll off set at around 50-60Hz to limit the really deep bass going to them. Another thing that you can do which will help a lot is limit the massive dynamic peaks that movies tend to have by using the 'night mode' option on your Yamaha receiver which will reduce the dynamic range.

 

[Laurens_B]

Thanks for your responses.

I don't have a subwoofer, just a 2.0 set-up, that's why I've not used the rolloff for the front speakers. Also, I used the DSP "Movie Theater: Standard", which gives me better dialogue, but probably also enhances the bass a bit. I listen to music mainly, which is why I am not really in the market for extra speakers/subwoofers (quite expensive upgrade!). Maybe I can experiment a little bit with it later today. I really fancy the speakers so I would not want to do anything to damage them, so I will be a bit more cautious next time I guess.

 

[michael hoy]

"The volume was at -12.5dB by the way. I watched the rest of the movie at -15dB."

That volume is really loud, do you have an extremely large room.

I would try what has been suggested and try again at reduced volume.