The trick in building a vented box is to get the right size enclosure and the right size vent. You can't be too far off on either of these factors or your speaker's performance will suffer. In particular, using a too-small box or a too-high vent tuning frequency can eliminate bass instead of increasing it.
1 Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. 2  Symptoms include severe joint and muscle pain, swollen lymph nodes, headache, fever, exhaustion, and rash. 3  The presence of fever, rash, and headache (the dengue triad) is characteristic of dengue fever.
The principal symptoms of dengue are: 1  High fever. 2  at least two of the following: 3  Severe headache. 4  Severe eye pain (behind eyes). 5  Joint pain. 6  Muscle and/or bone pain.7  Rash. 8  Mild bleeding manifestation (e.g., nose or gum bleed, petechiae, or easy bruising).engue hemorrhagic fever (DHF) is characterized by a fever that lasts from 2 to 7 days, with general signs and symptoms consistent with dengue fever. When the fever declines, warning signs may develop.