Quote Originally Posted by usbmusic
A quick question for you. Do you fill lead shot or sand in those PVC?
No, but I'm sure sound do resonate inside of tubes. I'm just not concerned about that, and doubt I will hear the difference.

I believe the key point is to stagger the distance between tubes. The difference distance should diffuse different sound freq.
The DIY site I saw had suggested to use poly-stuffing to reduce resonance.

One thing I hadn't considered is the material used for tubes. I'm sure different material and thickness will impact the sound, but they are too ugly for my taste.