Outmoded Electronics: January 2023

I’ve been looking into building some more absorptive panels for my room. I wanted to build something as close to a floor-to-ceiling corner superchunk as I could. I wanted more coverage than my 24”x48”x4” OC703 panels could provide. I wanted to crudely emulate the rectangular GIK Soffit Traps.

I bought a roll of Johns Manville R30 fiberglass insulation since it was the most readily available and least expensive option at the time. I will be cutting 15”x15” pieces of insulation, and stacking into a 37” high frame. Using 2”x2” furring strips, the external dimensions of each frame is 18”x18”x37”. The base is 1/4” plywood, while the top cap is 1/8” hardboard. Each front corner will get two of these frames.

Frames to be filled with fluffy insulation.

I originally thought of using PVC moulding to hide the staples and fabric edges. I may go the frugal route and use white tape instead.

I bought a couple of bags of Rockwool Safe N Sound to make 6” deep panels for reflection points. These panels will hopefully cut down on any ugly slapback reflections for when I record drums. I am using the cheapest 1”x8” ledger board from Home Depot. These frames are less labor intensive than the ones for the R30 above. The wood is pretty rough, and will require sanding. I plan on painting the boards a few coats of white.

8” Ledger Board Frame for 6” Rockwool.

Edit - 4/21/23 - I completed the rectangular fluffy traps and 6” Rockwool panels. A single layer muslin isn’t enough to hide the wood underneath; a second layer is needed for a uniform white look. It’s not so much of a concern with the Rockwool panels, but the fluffy frames really needed the second layer.

15.5”x 71”x6” Safe N Sound panel.

Left corner.

Right corner.

Room layout.

I used Room EQ Wizard to measure the effect of the panels on the left side of the room, since the bass response was most uneven on that part of the room. The image below shows measurements of the untreated corner (red), OC703 4" corner panel (blue), and the new fluffy traps with early reflection panel (green). The treatment improved the nulls at 99, 124, 156, and 185 Hz.

Room EQ Wizard 40Hz to 400Hz

The low end is still ugly, but there is a tangible difference. There is still a buildup of 60-80Hz that I will have to investigate, Perhaps some rockwool place above the ceiling tiles in my listening position will help evening out the response.

Edit - 4/26/23 - I moved my speakers closer to the wall (18” vs 4”) and the bass response evened out considerably. The 300Hz range worsened, so I will need to experiment with monitor placement a bit more.

Edit - 2/16/24 - I started to build some more frames again, experimenting with different lumber sizes. One method I’m trying is to glue 1x4 furring strips together to achieve 7” actual depth. The 1x4 lumber typical does not have as many twists as the 8” boards that I was sourcing from Home Depot. I can further straighten out a furring strip when I clamp a crooked one with a straighter specimen. A reinforced frame with outside dimensions of 33”x72”x7” requires 7 total 1x4 strips at $3.32 each.