Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6259798 | Passive radiator cooled electronics/heat sink housing for a powered speaker | Calvin C. Perkins, David D. Bie | 2001-07-10 |
| 6176345 | Pistonic motion, large excursion passive radiator | Calvin C. Perkins, David D. Bie | 2001-01-23 |