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RR Copland CD speaker killer?

I am wondering if someone with some know-how would like to guess what my technical problem is. I have Aerial Model 6's. When I play the Fanfare for the Common Man from the RR Copland CD the field drum makes my speakers crackle (that's the best word to describe the sound, which seems to come from the tweeter?!). This phenomena happened while the speakers were being driven by my old 300 watt amp (McIntosh) and still my new Rowland Concentra (the 100 watt version). So is it the amp clipping or is the speaker taking in too much power to try to reproduce the drum, even from the Concentra? (I am not sure what kind of peaks it can produce). As a test I did listen to my disk with headphones, and it does not crackle. At lower levels it also does not crackle on the speakers. I am talking normal listening levels here, as well; nothing ear splitting by any means. So are the speakers wimpy or what? This is the ONLY recording (out of many "heavy duty spectacular" types)I have that can make these speakers do this...any ideas?
jimmy2615
twl
3,251 posts
 
When an amp clips, the waveform(simplified) looks like a sine wave with the peaks cut off flat.All of the energy above that cut off peak has gone straight to your tweeter in the form of distortion and distortion harmonics. Due to its nature, it is not filtered out by the crossover network, but slams right into your very fragile, low power handling tweeter. Avoid this practice. Yes, your amp is clipping, but don't be alarmed, all amps will clip when driven hard enough, especially on transients like the one you mentioned. Your very fine amp is simply running out of gas trying to reach the volume you are pushing it to. If you can't get the volume that you want with that speaker/amp combo, then you need to change something or lower the volume. The reason that CD(?) is the culprit is that the dynamic range difference from the normal passages to the drum hit is greater than your amp can bear, at the volume you are using. Many of us here have experienced similar circumstances, which is why there are so many amps for sale in the classifieds. You also could change your speakers to more efficient types instead of changing the amp, if you would rather keep the amp than the speakers. Or you could just turn it down a bit which is MUCH cheaper.
mejames
986 posts
 
the speakers cones are bottoming out
twl
3,251 posts
 
Jimmy, I just checked the specs on Aeriel 6's and they are only 85db efficient. This low efficiencly will send a lot of amps into clipping trying to achieve high volume peaks. Briefly, you have to double the power for every 3db volume increase you want, so you'll roughly need 128 watts for 106db peaks. Your amp would probably do this, but the speaker also has a 4ohm impedance dip that may limit the amp's headroom. If you are trying to reproduce a peak louder than that, you are into at least 256watts. And that's at 3ft from the speaker. Significantly less loud at the listening chair. So, if you're cruising along at 100db and along comes the bass drum with a dynamic peak that's more than 6db higher than average - you're toast(clipping).
dweller's avatar
dweller
2,152 posts
 
Could be a manufacturing defect of some kind. An Ace-of-Base CD I owned made a sound like a sliding patio door slamming shut (on the "all that she wants" cut...). The Best Buy agent couldn't hear it on the boom box he tried (can't imagine why) but took my word and let me return it.
This happen to anyone else?
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