
Velvet Elvis
Ahh humma humma humma
Those math calculations make me want to vomit 
I'll be patient, Rick.. thanks for your work!!
Jim

I'll be patient, Rick.. thanks for your work!!
Jim
Rick,
that isn't anything you want to use with this - all of this is based first on a decrease in velocity - and the baffles are next - the absorbing interior is minor - and we definately don't want to get involved in tuning tubes for these purposes.
Rod
You're the expert.Ok, sounds good to me.that isn't anything you want to use with this
That reminds meSo is this saying that any old baffle that allows the air velocity to decrease (by increasing volume) and contains some 90 degree bends in it will do the trick?
That reminds mewhat diameter is your flex ducting?
See my drawingThe one that you assume is a return from the drum room is actually a feed to the second floor of the house...The return in the drum room has not yet been placed, so it can go anywhere.In that obscure corner?
The feed to the drum room is rigid pipe right now, from pre-existing work in the basement, but I plan on changing it to flex and will have the ability to move it over a few trusses if we want.
NO WONDER!
Then WHAT is the flex line in the middle of the drum room?? To the upstairs? Actually, here is what would be ideal.