B&W CM1 Crackle/distort with low frequency movies

[admin_exported]

Hi guys, I've had my CM1's for a few months now and have noticed on some low frequencies they emit a loud crackle.

Has anyone else noticed this or can advise what the problem might be. They are used as the main stereo pair via my Marantz PM6004 amp. I haven't notice this happen with any music I've played, only film, especially low rumbling effects.

Any advice much appreciated.

 

[Frank Harvey]

Music generally doesn't have much low frequency energy below 40Hz, but movie soundtracks from a Bluray can reach below 10Hz - which hi-fi speakers aren't designed to do, and definitely aren't capable of doing. To reproduce very low bass notes, the bass cone needs to move further, and there's a limit to what all bass drivers can do, especially smaller ones. As your speakers won't reach 20Hz, I'm guessing it is probably excessive bass between the 25-35Hz point that is causing your speakers problems. Other than using the bass control to turn bass down, there's not much you can do without adding products. Adding a sub to deal with these lower notes is the simplest way to stop this happening. You need to look for a subwoofer with speaker inputs and outputs so that it can be placed between the amplifier and speakers - it will then filter out the lower notes and pass the rest on to your speakers. The downside to this is that the sub will always be in circuit. I would also generally recommend a sub with a minimum of a 12" driver, otherwise you'll be lucky to break 30Hz with any meaningful grunt.

 

[Ben123]

Im running the CM1s with a marantz pm7000 amp (for music) and dont have the problem you describe. However, i am watching films through an Av amp so the lowest frequencies dont get sent to the CM1's. I play my CM1's quite loud at times so they can certainly take a beating without distorting.

I take it theres no alternative amp / speakers you could borrow off a friend to find the cuplrit? Also, is the crackle there at low volumes?

The only advice i can give is to back off on the volume when you experience any crackle / distortion. Personally, i would disconnect my cm1's from anything that crackles until i found the culprit - but thats me.