Theory on Damping

[coolhandjjl]

I had my Cerwin Vega D9's (bass reflex design) open the other day and noticed damping material on just three sides. Looked inside my pair of JBL L100's, (bass reflex design) and saw the same thing. Damping on just three sides.

Can there be too much damping? Is there something to this leaving one side as a hard surface like to help reflect the waves out to the port better?

[Bill Fitzmaurice]

Is there something to this leaving one side as a hard surface like to help reflect the waves out to the port better?

It's called cheaping out. All surfaces should be damped, and the last thing you want is for waves to reflect out the port.

[coolhandjjl]

It's called cheaping out.

Thanks for clearing that one up Bill!

[Bill Fitzmaurice]

There actually is an explanation for not damping all panels. It was once thought that damping was only necessary to control low frequency standing waves, and that if you damped only one of two opposing panels you were good. That theory dates to the 1950s. It's been known since the 1970s that damping is even more important to prevent any internal midrange reflections that might go back to the cone or out a port. If the cabs in question date prior to the 70s they may be forgiven, but otherwise no.

[coolhandjjl]

Actually, I had read the thing about not damping everywhere on a forum that discusses old Altecs and Klipsch Cornwalls, so that makes sense.