Tc-sounds VMP 12 Manuel d'utilisateur télécharger pdf (Page 2)

VMP 12” variable mass passive-radiator

Fix and Variable Parameters

Parameter

12" VMP

Description

Qms

Mechanical Q

Cms

um/N, compliance

Dia

250

m meters, effective

Mms (Range)

390 - 2160

grams, effective mass

Fs (Range)

30 – 11.7

Hertz, Free Air Resonance

Empty

Nut

Mass (washers)

Resonance Frequency

for e

Directions for Use

VMP’s are designed to supplement ports in bass-reflex systems. The TC Sounds VMP can be tuned lower by adding

mass washers or higher by removing them from the adaptor under the cone. Adding additional VMP’s is equivalent to

increasing the port diameter in a ported system, and adding mass to a VMP is equivalent to increasing a port’s length.

Adding a second VMP to the system effectively raises the net tuning and additional mass must be added to both

VMP’s to maintain the same system tuning frequency as opposed to using just one VMP. Additional VMP’s increases

the resonator’s headroom and allows the subwoofer to push more air before compression. Ideally two same-sized

VMP’s should be used with one active driver, but TC VMP’s can be utilized on a 1:1 ratio in small box systems with

good results. If only one VMP is used, the subwoofer may be subject to shaking due to mass imbalance. This does not

have any sonic problems, but fastening the enclosure may be necessary. Two opposing VMP’s will mass-cancel and

eliminate shaking.

The above graph shows the free-air resonances of a VMP as additional mass-washers are added. For modeling a

passive radiator system with a VMP, use any Fs number from the graph you like in addition to the fixed Cms, Qms

and Cone Diameter above. Note that during the first few uses, the VMP will break in and the compliance will increase

therefore lowering the effective Fs.

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Tc-sounds VMP 12 Manuel d'utilisateur Page 2