Each panel consists of the following:
- 2 Long Frame Pieces – 48″ L x 2″ W x 3/4″ T
- 2 Short Frame Pieces – 24″ L x 2″ W x 3/4″ T
- 4 Corner Braces – Triangles cut from 1/4″ plywood
- 1 Support Strip – 48″L x 1″ W x 1/4″ T
- 1 – 24″ W x 48″ L x 2″ T Rockwool Insulation Panel – https://www.acoustimac.com/roxul-rb6-2in
- Painter’s Plastic Wrap – https://amzn.to/3PkjAoO
Since moving to a new workshop in Missouri, the audio quality in videos changed noticeably due to increased reverb. To address this, the solution was to create DIY acoustic panels to cut down on the harsh reverb in the space.
Understanding the Problem: Reverb in Your Workshop Spaces
Reverb, or reverberation, is the persistence of sound after the original sound is produced, caused by reflections from surfaces such as walls, ceilings, and floors. In a workshop setting, this can be particularly brutal, affecting audio clarity in videos and conversations.
Materials and Design Considerations for Acoustic Panels
The goal was to build 36 acoustic panels efficiently and economically. The design consists of:
- A plywood frame made from 3/4 inch plywood.
- A 2-inch thick rockwool insulation core inside the frame.
- A very thin plastic wrap around the rockwool to contain loose fibers.
- An acoustically transparent fabric covering the entire panel for aesthetics and sound permeability.
Why Rockwool?
Rockwool insulation is preferred because it holds its shape well, unlike loose-fill insulation which could fall out. It provides a stiff structure that does not compress easily, making it ideal for acoustic panels.
Safety Considerations
Rockwool can shed fibers, which may be irritating to breathe. Although research indicates it is not carcinogenic, wearing a mask when handling it is recommended. Wrapping the rockwool in a thin plastic film (.31 mil thickness, which is 0.00031 inches) helps contain fibers without significantly affecting sound absorption.
Building the Acoustic Panels
Cutting the Frame
- Start with sheets of 3/4 inch plywood.
- Cut the sheet in half, then rip into strips a little over 4 inches wide.
- Cut some strips to 24 inches for the short sides and leave others at 48 inches for the long sides.
- Cut 1/4 inch plywood into small triangles to reinforce corners.
Assembly
- Assemble the frame using glue (Titebond Quick and Thick) and brad nails.
- Add 1-inch strips of 1/4 inch plywood vertically inside the frame to prevent the rockwool from falling out.
Preparing the Rockwool
- Cut the rockwool panels to fit inside the frame, accounting for the frame dimensions.
- Wrap the rockwool in the thin plastic film for fiber containment.
Covering the Panels
- Wrap the entire panel in acoustically transparent fabric.
- Staple the fabric on the back and trim excess.
Installation and Placement
- Hang the panels from the ceiling using hooks and screw eyes.
- Leave about an inch of air space between the panel and the wall to allow sound to be absorbed from both the front and back of the panel.
Effectiveness and Sound Testing
- Sound tests were conducted by recording voice samples with and without panels, and with panels covered and uncovered by plastic.
- No audible difference was found between plastic-covered and uncovered panels, but a clear improvement was noted when panels were used.
Additional Tips and FAQs
Do You Have to Use Rockwool?
No, other insulation types can be used, but rockwool is preferred for its shape retention and stiffness.
Is Thicker Better?
Thicker panels absorb lower frequencies better, which is important for home theaters or critical listening spaces. For vocal frequencies, 2-inch panels are sufficient.
Is the Air Gap Necessary?
Yes, allowing an air gap behind the panel improves absorption by letting sound reach the back of the panel, effectively doubling the absorption surface.
How to Position Panels?
Focus on walls where sound reflections are strongest, typically side walls. Alternating the pattern of panels can maximize absorption with fewer panels.
Conclusion
Building and installing DIY acoustic panels is an effective way to reduce reverb in workshop spaces, improving audio quality for videos and conversations. By using economical materials like plywood and rockwool, and following thoughtful construction and placement strategies, you can create a more acoustically friendly environment without breaking the bank.
This first line of defense against reverb can be expanded upon with additional treatments as budget allows, but even these panels make a significant difference in sound clarity.