"bj" wrote in message
om
It is said that at least 28.5 feet length room is required for the
control room cuz I thought the wave length of 20hz is 56.6 feet

The idea that small rooms can't support low bass is an old wive's tale. In
fact its completely bass ackwards.

Small rooms support bass better than large ones. In essence there is a 12
dB/octave boost that commences at some frequency inversely proportional to
the size of the room.

For a small room the boost starts at a higher frequency, while it starts at
lower frequencies in larger rooms.

This is one reason why bodacious bass is more feasible in automotive
applictions - the listening room is effectively quite small.

A synergistic match between speaker and room can be achieved when the
speaker's bass extension starts cutting out just as the bass boost due to
the size of the room starts cutting in. Of course some of this might get
swamped by other room resonances.

One thing that can happen is that the automatic bass boost due to a small
room can cut in at such a high frequency that its not bass boost anymore -
its midbass boost. Then things tend to sound thumpy or wooly.

then, I am using Mackie Hr824 monitor speaker in my room
but my room is really small. most long length is just 12feet.

So how does it sound?