EPA Deep Bass Traps

Inspired by the great experiments done by Gernot Ebenlechner (G.E. on Gearslutz), i did some own tests with this bass trap design he babtized „EPA’s“ (Enhanaced Porous Absorbers), as described in these two threads:

• GearSlutz: My Experiment with a Metal Panel Absorber
• GearSlutz: Perforated Panel with Porous Absorber trap

The design described works with the well-proven porous absorbent Caruso ISO-Bond WLG 035, which is known for having superb deep bass absorption properties when used in higher thicknesses. The experimental results of G.E. showed that, by adding a 2mm DC01 steel plate sandwiched by the ISO-Bond, the deep bass absorption below 100Hz is getting pretty effective also with overall thickness down to 10cm. Details about the construction are published by G.E. in the threads linked above, also a in-detail documentation about the construction of our new mixing room is published on this website soon, therefore i just outline the major results in this post – which are pretty astonishing 🙂

These are the before/after spectrograms (made with REW) of a test with an empty small room, measurement microphone in the upper corner of the front wall, the speaker (a Tannoy System 12 DMT) at the corresponding lower corner, and the installed bass trap (if present) at the opposite corner of the mic/speaker. The reduction of the 50Hz mode (1-0-0) is pretty drastic for a bass trap just 10cm thick!

ps.: The foto is taken in another room with the monitor placed differently than during measurement, but the EPA construction during the test was exactly the same.