Newbie Question - effect of extremely low frequencies on speakers

[davidmigl]

Hello,

Can extremely low frequencies (1 - 20hz, generated by an audio editing program) damage bookshelf speakers when they are played for short periods of time (say, 15 min)?

 

[MACCA350]

Bookshelves can't produce frequencies that low, so playing them wont damage them. Try it and see if the cone moves when you play only those frequencies, if it doesn't, then there wont be a prob.

cheers

 

[markw]

good answer, but yes and no on the first part.

Bookshelves can't produce frequencies that low, so playing them wont damage them.

Under normal circumstances you are correct. But, if one feeds that teeny little speaker enough power it WILL move. ...not enough air to be felt, but it will move and most likely produce extremely unplesant harmonics and other noises at the same time.

Of course, it's drawing much, much more power than it was designed for and it will heat up big time and it's life will probably be very short.

 

[MACCA350]

My apologies, markw your right.
I just tried it out on my towers (I thought even they wouldn't move below 20Hz). I removed the covers, Set them from small to LARGE, with no sub on the receiver, and played some sine-waves through the HTPC(which has a digital connection to the receiver).

What happened next surprised me, the cones were moving full throw in and out sweeping out a 10Hz tone(this is the lowest tone I could find), I couldn't hear any noise from them or any windows rattling(10Hz through the DD15 gets the windows and walls pounding ) so there is very little SPL down there, but as you said they will react to those frequencies.

This just reinforces the need to have, even towers, run as small so your not wasting amplifier power on those low frequencies that have virtually no SPL.

cheers