My man-cave is my car and that is where I enjoy music the most. I know it is an acoustically unfriendly environment, but with decent equipment and tuning, one can get pretty decent sound. I will probably end up using a DSP (electronic equalizer) to dial in some troublesome spots, but thought I might try to accomplish what ever is possible with acoustic treatments. When I RTA my truck, engine off, there is quite a bit of heaviness below 60 hz, I might have to DSP that since I haven't the room required for broad band (or tuned traps?). But I have a pretty big bump at about 250 hz. I thought I my try a plywood panel membrane trap-Ethan's design calls for a 2x2 frame with OC 703 and 1/8" thick plywood. My question is, would two traps totaling about 4 sq ft (not funny) be enough area to make a measurable difference? They would back behind the back seat against the rear wall of the truck cab.
Post by Michael Lawrence on Dec 12, 2018 0:04:41 GMT
Hi Jim- Welcome. I can't comment on your specific situation but that area seems far too small for effectiveness. You're asking about a measurable difference, so you should...measure! You can use an open loop measurement with Room EQ Wizard, before and after stuffing your back seat with blankets, pillows, or pink insulation to see how much of a difference can be achieved. That would be step 1 for me.
No change with a bunch of foam behind the seat. I tried just under the front edge of the back seat and noticed some drop (maybe 5 db). The distance from the foam to the back of the cab is about 17 inches. Maybe I can try a 4-6" trap with oc 703 frk?
If you have a big bump at 250Hz then it's probably because you were centered from several boundaries that were the same distance away. You can try measuring different points which are off-center or you'll have to add absorption to your truck's surfaces. Measure from your driver's seat, passenger, and rear seats to see how that response changes.
Is you truck's interior high-end? IDK but aren't some interiors designed for acoustics and pretty dead? If you seats a leather or pleather you might consider re-upholstering your seats with open-cell foam and cover with open weave fabric. Check your waterfall graph, if the modal ringing isn't too bad (too long) maybe EQ ing for your drivers seat will do the trick. If it's mainly for you, do you care about the other positions?
2008 Tundra. Not a high end interior, cloth and plastic. I think cloth is better than leather for acoustics.
I used an RTA polt just from the driver's position. I can also make adjustments for the front passenger to enjoy but not both together. Equing may be the best adjusting I can do. I was hoping to get some increase sound quality before monkeying with speaker out put. I did do some 1" acoustic cotton on the headliner which calmed things down a bit a while ago. But bass is the hardest to tame.
As far as I know, best practices state that you use as little subtractive EQ below the space's Schroeder frequency as possible. I don't know what that is in a truck but, from what I understand, the smaller the space, the higher the S.F. Maybe you can get away with notching the 250Hz.