Yes, there are several other factors besides thickness that can affect the sound quality of DML speakers:
- Panel material – The density, stiffness, and internal damping of the panel material impacts frequency response, resonance modes, and efficiency[1][2].
- Exciter type and placement – The exciter must be properly matched to the panel and placed at optimal locations to evenly excite all resonance modes[3][4].
- Boundary conditions – How the panel is mounted and constrained affects the vibration behavior and resonance modes[4][5].
- Damping – Adding damping material can reduce resonances and smooth response, but too much damps efficiency[1][2].
- Equalization – DSP correction is typically required to smooth the inherent peaks and dips due to resonance modes[3][6].
- Dispersion – Wider dispersion panels provide more even coverage. Narrow panels can cause uneven off-axis response.
- Enclosure – Adding a rear enclosure increases low frequency output and efficiency but changes dispersion.
- Room acoustics – The listening environment can accentuate or attenuate certain frequencies due to room modes.
So in summary, many factors beyond just panel thickness impact the resulting sound quality of DML speakers, from design to setup to the listening room itself. A holistic approach is required for optimal results.
Citations:
[1] https://www.diyaudio.com/community/threads/a-study-of-dmls-as-a-full-range-speaker.272576/page-55
[2] https://www.audiocircle.com/index.php?topic=70541.3060
[3] https://www.mdpi.com/2076-3417/10/24/8926
[4] https://projectgallery.parts-express.com/speaker-projects/dml-flat-pannel/
[5] https://forum.audiogon.com/discussions/which-material-sounds-better-for-speakers-construction-wood-ply-or-md
[6] https://techtalk.parts-express.com/forum/tech-talk-forum/64791-diy-flat-panel-speaker-love/page26