The thinking among drum designers had been that the relatively small mass of metal attachments would not affect the instrument’s overall sound. However, experiments revealed otherwise.
Typical tie-down hardware stiffens wooden drum shells and raises the drum’s pitch. This hardware is usually tube-lug anchors that also tension the drum head. Threaded inserts on either end of the anchor let a tension rod (screw) pull on a steel hoop pressing on the head. Tension around the head is distributed through a channel-shaped collar into which the head is epoxied.
The tube lug acts as a mechanical bridge and stiffener where it attaches to the shell. At Head Drums, developers say the lugs can also contribute high frequencies to the overall sound because their natural frequency is higher than that of the wood they are attached to.
A new lug design, dubbed Top Hat, eliminates such interactions. It has a single point of contact with the shell and thus is largely uncoupled from the hardware needed to tension the drum head. Head Drums designers say the result is a finished shell with a lower natural frequency and a purer tone.