From my 3-way speaker building experiences, I know the enclosure for midrange is absolutely necessary for the closed speaker design. Otherwise, without sealing, the diaphragm of midrange drivers will move while reproducing sound due to the pressure inside the cabinet causing distortion to sound. However, in vented system, will the situation change and the sealing/enclosure for midrange still be necessary?
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YSDR, may I ask the reason why? I think the vented system has much less pressure inside the cabinet since the air can exit at the port, so the diaphragm of midrange will no longer move by the pressure. But this is only my assumption.
The air does not exit at the port, instead the mass of air inside the port vibrates to and fro.
The port starts producing some of the sound from around an octave above tuning, and by the tuning frequency all of the bass is produced by the port, with nothing being produced by the woofer directly. The woofer’s travel at this point is minimised to almost nothing at all.
The port starts producing some of the sound from around an octave above tuning, and by the tuning frequency all of the bass is produced by the port, with nothing being produced by the woofer directly. The woofer’s travel at this point is minimised to almost nothing at all.
At the port tuning frequency, the internal box pressure is much larger than in a sealed box, moreover there can be not just low freqency pressures but higher frequency content, which can radiate out through the midrange membrane if the mid-driver is not sealed.
i have tried at first with my 6.5inch and 15inch driver and both speakers act as a passive radiator .. enclosure IS necessary unless you put your medium in OP baffle outside the speaker 😉
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Away from port frequency the woofer box volume excitation is the same, so no breaks there on mid isolation. At port frequency the box excitation is increased, so no breaks there either. Only below low cutoff is the woofer pressure let out compared to sealed.
The air in the reflex enclosure acts as a spring while the air in the port acts as a mass.
Around the tuning frequency, the to and fro motion of the air mass in the port causes the volume of air in the enclosure to alternately increase and decrease and the pressure in the enclosure to alternately decrease and increase.
So, there is no escaping the fact that an open back midrange driver will be subject to the changing air pressure inside a reflex enclosure.
Around the tuning frequency, the to and fro motion of the air mass in the port causes the volume of air in the enclosure to alternately increase and decrease and the pressure in the enclosure to alternately decrease and increase.
So, there is no escaping the fact that an open back midrange driver will be subject to the changing air pressure inside a reflex enclosure.