How to Mount a Speaker in Quartz Chime Clocks?
We often hear complains about the sound of the clocks not being clear or lound enough. It is true that some quartz chiming clocks seem to sound much better than others. A major factor of sound quality is how you mount the speaker.
If the speaker is mounted inside the case and the sound cannot project outward. These clocks have quiet, tinny sounding chime. The best solution is to have the speaker mounted over an opening in the case. The sound of these clocks is rich and full-bodied. The volume of sound can also be louder. Most Hermle clocks have the speaker mounted this way.
For example, Hermle Austen Quartz Clock has the speaker mounted at the bottom
the speaker is mounted over an opening in the bottom of the case. The case bottom acts as a baffle for the speaker, creating a rich, full chime sound.
In Most Hermle regulators such as Hermle Shenandoah, the speaker is mounted at the top
the speaker is mounted to an opening in the top of the case. The the top board acts as a baffle for the speaker, allowing good volume and clear, rich sound.
When a speaker does not have a baffle around it, the sound waves generated by the front of the speaker cone cancel out the sound waves generated by the back of the cone below a certain frequency. A speaker used in clocks is small so all the bass response generated by it is lost. Mounting the speaker on a baffle such as a wooden board creates a longer path for the sound waves, reducing cancellation. The larger the baffle, the lower the frequency response extends. Even a small baffle will make the speaker sound much better.
If you mount a speaker to the back of the movement and if the back door covers it, trapping the sound inside. This causes the chime to be very quiet and without richness.