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What are some factors that affect the sound quality of DML speakers?

Here are some key factors that can affect the sound quality of DML (distributed mode loudspeaker) speakers:

Panel Material
  • The material’s density, stiffness, internal damping determine the frequency response and resonance modes[1][2]. Common materials like acrylic, aluminum, wood, polystyrene etc. have different acoustic properties.
Panel Size
  • Larger panels can reproduce lower frequencies down to around 100Hz before needing a subwoofer. Smaller panels roll off sooner[1][3].
Exciter Type
  • The exciter must be properly matched to the panel material and sized to provide enough force. Insufficient excitation limits output[2].
Exciter Placement
  • Placing exciters at modal nodes results in weak excitation of some modes. Optimal placement excites all modes evenly[1].
Boundary Conditions
  • The panel mounting method affects resonance modes. Clamped edges induce different modes vs free edges[3].
Damping
  • Insufficient damping leads to ringing and peaks. Too much damping negatively impacts efficiency and frequency response[2].
Equalization
  • DSP correction is needed to smooth the inherently uneven panel resonance modes for flat response[1][4].
Dispersion
  • Wider panel dispersion provides more even coverage across a room. Narrow vertical panels give uneven coverage[5].
Enclosure
  • Backing the panel with an enclosure increases low frequency output and efficiency[3]. Open-back panels radiate from both sides.
Room Acoustics
  • The listening environment can exaggerate or attenuate certain resonance modes, affecting perceived sound[3].

So in summary, the panel material and size, exciter design, placement and tuning, boundary conditions, damping, DSP, dispersion pattern and room acoustics all play a role in the resulting sound quality.

Citations:
[1] https://www.diyaudio.com/community/threads/a-study-of-dmls-as-a-full-range-speaker.272576/page-36
[2] https://dmlspeakers.com/articles/101%20-%20Introduction%20to%20Distributed%20Mode%20Loudspeakers
[3] https://publications.lib.chalmers.se/records/fulltext/154618.pdf
[4] https://www.researchgate.net/figure/Frequency-response-function-of-the-DML-system-before-and-after-enhancement-DML-solid_fig17_11915705
[5] https://www.revolutionacoustics.com/technology/
[6] https://hackaday.com/2019/10/26/building-the-worlds-best-dml-speakers-for-under-115/