VMPS Speakers Use Putty on the Bass Driver

[caesar148]

I noticed that VMPS speakers require putty to be loaded on the bass driver in order to get an accurate sound level. VMPS' reason is that different environment require the bass to be tuned. The users adjusts the weight of the putty until the "right" amount of bass is achieved.

This seems contrary to what I understand how drivers should work. The ideal speaker driver should have zero mass so that all the energy is used to drive the air. With mass on the driver, inertia is added and this will result in overshoot and even oscillation. Is loading the bass driver the right approach?

 

[catapult]

The putty is on the passive radiator, not the bass driver.

 

[BillFitzmaurice]

Even if it was on the driver that's a common mod used for decades to alter the Mms and thus the Fs, Qes, Qms, Qts. Bl and about a dozen other driver specs. But in the case of a passive it adjusts the passives tuning frequency.