Monitor Audio BX Series - Manual (Page 12)

Bronze BX 10
Port Bungs
WARNING: Care must be taken not to insert the port bungs too far into the port as
this may result in the foam bung being lost inside the cabinet.
If the loudspeaker is to be used in a small room, typically 9 sqM (80 sqFT) or a room
that is known to reproduce accentuated bass response, it may be desirable to fit the port
bungs. However, before this is done it is worth experimenting with the positioning of the
loudspeaker in the room. To reproduce the optimum performance from the loudspeaker it
is important to make sure the loudspeaker is not positioned too close to a wall (typically
150mm / 6” from the back of the cabinet) or near corners of a room (typically 1M / 3FT).
If the room is larger than detailed above and no problems are known, please read point 1.
If the positioning of the loudspeaker is predetermined by room aesthetics or layout, please
move on and read point 2 for the BX1/ BX2 and point 3 for the BX5/ BX6.
Port bungs might not be necessary on the BX2 even if placed close to a rear wall due
to the front firing port tube. Experimentation is still highly recommended though.
1. If you can adhere to the room characteristics detailed above we recommend that you
do not fit the port bungs to achieve the best performance. However you may feel that
by fitting the bungs even under these circumstances provides you with a degree of
fine-tuning to suite particular taste. Experimentation is highly recommended.
2. Where a bookshelf/ stand-mount speaker with a rear firing port tube (BX1) is to be
used in close proximity (2”, 50mm) to a rear wall such as on a bookshelf, positioned
in a cabinet or mounted on a wall, we recommend fitting the port bungs to the ports.
This will reduce the bass ‘boom’ sometimes termed as overhang, and assist the
loudspeaker to reproduce its best performance under the environmental constraints.
‘Boom’ is generally caused when bass energy from the loudspeaker ‘excites’ room
modes and causes an accentuation at a particular frequency, or number of frequencies.
3. Where a floor-standing loudspeaker (BX5 & BX6) is to be used in close proximity (closer
than 150mm 6”) to a rear wall, we recommend fitting the port bungs. This will reduce the
bass ‘boom’ sometimes termed as overhang and assist the loudspeaker to reproduce
its best performance under these environmental constraints. This is caused when bass
energy from the loudspeaker ‘excites’ room modes and causes an accentuation at a
particular frequency, or number of frequencies.
Where the loudspeaker has two ports per speaker, BX5 and BX6, a further degree
of fine-tuning is provided. In this case you have three options; to leave all the ports
open (point 1), fit the port bungs to the rear ports or to fit a port bung to the front
port. We recommend that you experiment with fitting the port bungs to the rear port
or the front port in succession as the results can vary dependant on room acoustics
and positioning. The overall bass extension will not be reduced, however the bass
energy/ output around the port tuning frequency will be reduced. This has the effect
of reducing bass ‘boom’ increasing bass clarity and apparent agility. Experimentation
is highly recommended.
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