Speaker Design, Speaker Building: Loudspeaker Design & Construction

Loudspeaker Driver Mounting

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Drive Unit mounting in loudspeaker enclosures

Fixing the drive units to the loudspeaker enclosure securely is very important, especially for low-frequency woofer units, which cause a lot more vibration.  The object should be to isolate the speaker frame’s vibration, in order to lower noise emitted by the cabinet.  Attachment is via the flange on the speaker chassis created for this purpose.  This will usually have holes pre-drilled for mounting.

The most common method of doing this is using nuts or screws.  These are commonly available, cheap when bought in bulk and permit easy removal of the drive unit for maintenance or replacement without spoiling the cabinet appearance.  Any form of fastening needs to be resistant to the large amounts of vibration caused by a drive unit. 

 

Spring Washer and nut

Cheap device that relies on small compression spring providing a tension force, which deters the nut from unfastening.

Shakeproof (Star) Washer

The stars of the washer embed themselves in the drive unit surround, relying on friction to prevent unfastening.  Has the potential to damage drive unit while embedding however.

Tab Washer

 

These could be used with the tab of the washer folded over the edge of the drive unit flange.  Would prevent tightening should this inevitably be needed, and need to be disposed after removal for maintenance or replacement of drive unit.

T-Nut

This nut digs into the interior of the speaker, thereby tightly affixing the bolt to the the actual enclosure

Nylon insert self-locking nut

This gives a tight fixing due to the bolt thread cutting it’s own path in the nylon insert.  The nylon may also allow some dampening of vibration to occur.  Must be replaced after removal, however.

Well-Nut

A free floating fastener commonly used to damp vibration in electric motors.  Well-nuts are a rubber insert with a brass nut embedded in the base.

On the reverse side of these nuts would need to be a bolt or H.T.S. set screw.

Another simple technique is to mount drivers with an adhesive.  This could be a plastic cement such as scotch glue.  Scotch glue would be cheap, readily available, and adequately strong for the purpose, providing a flush fit between the drive unit flange and loudspeaker cabinet is ensured.  However, it may be difficult to work with, taking little time to cool and being messy before needing to be left overnight to set.

A more attractive adhesive for the purpose may be silicone adhesive.  This is much easier to work with, supplied in a canister format.  This would provide an air-tight seal with the drive unit and a degree of vibration dampening also.  A critical disadvantage with any form of adhesive is the difficulty of removing the driver if it has been set into the cabinet.

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