Build log: DIY rotary sub for contemporary HT in 100 year old house? - Page 42

HT related this weekend: um, installed two shop lights in the basement. Wow, I wish I had done this earlier. I have been using one of those lights with a hook and hanging it wherever I'm working. The shop lights are so much better. Now, if I could just get some more lighting in the theater itself.

Cuzed, RT, I appreciate letting me know now what I'm in for. Approximately how much do you think this sweet little girl will disrupt my life??



RT: That is hilarious about your BIL. I hope it doesn't come to that....although *now* that I've put some money into the system it *should* sound better than it does. I wonder if I get new ?XYZ? will it sound better? Oh boy.

blackoper: I think it is a somewhat simple idea, but as with a lot of stuff the devil is in the details. My design mounts the fan, linkage and driver on a shaft supported on both ends with angular bearings. The shaft goes through the vent in the driver. Then I plan to use a 3 phase motor and speed control to turn it. One issue I am having is that if you leave the driver whole, you have a large cone (mine was 15") in the way of your airflow. The Thigpen is only 17" in diameter, so that doesn't leave you with much! If you cut out the cone, then the coil is only supported by one spider and the bushing of the linkage. You have to mount the driver in nearly perfect alignment otherwise the coil will rub on the magnet. There is very little clearance. In addition, the driver has this rather strong magnet that wants to pull it to the shaft which will basically crush the coil instantly. There are ways to mount everything in a order that would work, I think.

Also note that going "beefy" and with metal blades you will need a strong driver and you will need to calculate the max frequency it will do based on the additional mass you are adding to the "cone". I need to get to ~25 hz because I am using a folded horn above that.

I don't know if any pictures are left on either thread, but I can edit the links to them if you ask. (They are a pain to fix.) The new version of AVS broke all my pic links.

So, I cut a 2' x 2' hole in the wall of my beautifully sound proofed room to allow waves of ULF bass to come through. That is not a lot, but it is something.

I put a fan in the hole where the rotary goes and I could hear it on high, but not on low. If I opened the door to the theater, I could definitely hear the fan on low. So, there's some sound attentuation going on in that rotary cavity. I think it will be enough so that you don't hear the rotary unless the vanes are deflecting.

Yeah, I think that is why it took so long to do it!

I might rig up something to seal the hole when I'm not using the rotary...if I think I need it. The room with the rotary will be blocked off from the rest of the house with a wall so I shouldn't be getting too much infiltration from there, but then again my dehumidifier is there....but I have also thought to put the dehumidifier on a timer so it only runs at night. So many options when you have 2 months to think about things between doing actual (HT) things.

I could put in a switch, but it runs intermittently so if I started watching a movie and forgot to flip the switch the dehumidifier may kick on. I don't think it is a huge deal if the dehumidifier doesn't run all day long. It is a big unit. (insert joke here) I just don't want the concrete floors getting moist. If it is running every day it will be fine. It is when it doesn't run for a couple weeks that it starts getting musty. I can play it by ear though.

Yeah, I like the planning. Usually I know what I need to do next. I have a bunch of work that I know what needs to be done, but it is overwhelming to some extent.