[Closed] Ducting experts

I'm no expert, but rectangular looks like it would produce the least aerolic perturbation.

what sort of duct velocity are you planning on if it's less than 10 meters a second they'll both be very quiet. The main noise will be caused by bends in the duct so with the flat profile duct you'll need to look for a nice smooth bend rather than a 90 degree.

personally I'd avoid flexible ducting as it's cheaper but it always a ball ache in the long run

Depends on airflow you are trying to shift - and hence velocity.

Ducting hose will create more noise as it is bumpier - for a given size. But if the rectangular section is too small then velocity too high, then that will be noisier.

If you want least noise you need smoothest, straightest tube possible and largest volume (size) to reduce velocity as much as poss.

Thank you, I just needed to know if the noise was possible issue. I'm not sure offhand what the cubic square meters per second figure is.

What's the volume of the room? WxLxH x air change rate (say 3 or 4) and divide the answer by 3.6 will give the air flow in litres/second
Wouldn't go above about 2.5 m/s to keep it quiet enough for a studio; I'd also stick with circular duct over the plastic flat duct, but avoid flexible hose above as far as possible

For low noise applications you need a low static pressure (Can get really geeky) and low velocity within the duct, go for the largest duct that you can fit.

Out of those 2 I would go for the rectangular and not the flexi duct, but if you must go for flexi duct make sure it is the acoustic insulated flexi duct.

Also try to keep it all a straight as possible as any change in direction will introduce noise

Don't the 90 degree corners of the rectangle hurt it? They would certainly create drag.

I take the point on the bumpy surface of the flexible hose.