Originally Posted by Haz-Mat-Strat
Most HVAC ducts are sheet metal. Use an insulated flex duct, the ridges in the flex duct make it a quieter alternative. The flow is slightly reduced however the sound isolation is better.
Make sure to replace all of the rigid 6" duct. This eliminates any mechanical connection to the main supply duct.
A flex for the return will help also.
Making a "Baffle box" may impede the air flow.
Thanks for chiming in! I actually built about 3/4 of each baffle box this weekend.
I'm sure flex duct would help but I think in my case, baffles would be needed regardless (I'm no expert though). Even with flex duct, it would still be a short straight connection to the main chase; I would worry about significant transfer since I couldn't utilize any bends. That's why I chose the baffles; my hope was that they would provide maximum sound stoppage in the shortest linear distance.
There is a short run of existing galvanized duct that I had considered replacing with flex between the baffle box and main chase but I decided to leave i; I'm a bit worried that flex + baffle box would decrease the flow too much. The connection to the baffle box utilized a rubber gasket to decouple the two parts of the system so I'm not overly concerned about vibration traveling down the duct.
Airflow is definitely a concern. Based on conversations with my HVAC guy, the studio room is right in between needing 1 or 2 supply ducts. I decided to utilize two with baffle boxes; my hope is that any restriction will still provide above what 1 single duct would supply. I was also able to increase the area of the passage through the baffle box from what the 6" line supplies. I'm sure the turbulence in the baffle box will restrict the flow somewhat but, again, my hope is the total supply will still fall in the proper range.
Originally Posted by RonT
I hear this phrase echoing in the heads of many that did not listen!
I'm sure this is the case! I would have loved to go "full on" with this project but at the end of the day; it's a project studio in my residence and I couldn't justify that much $$. I do spend a significant amount of time in there, but it's not my day job.
I couldn't justify the $$ for a separate system and I didn't want to risk compromising the system's performance in the rest of the house. Basically I approached it from the basis of standard room construction (utilizing the majority of the existing structure and HVAC system) with a few cheap DIY methods to control sound transmission and treat the finished room. Will I regret this approach down the road? I give it a 50/50 shot.