ETS-Lindgren SMART 1000 Mini-Reverb Cell - Manual (Page 33)

Vents | 33
6.0 Vents
Honeycomb vents are used for the ventilation system of the enclosure and
normally do not require maintenance. The honeycomb vents work as a
waveguide beyond cut-off and are sized depending on the upper frequency of
operation of the chamber. High frequency rooms, therefore, use small bore
vents. Conductors of any kind must not be passed through the vents or the
performance of the vent will be drastically reduced.
Should the accumulation of lint or dust require that the honeycomb be cleaned,
the duct system on both sides of the honeycomb must be opened so that the
honeycomb vent may be vacuum-cleaned from both sides. The duct system
should then be reinstalled per the original construction.