Effective piston radiating area driver

A measured mass is applied to the cone forcing it back while the current required for the motor to force the mass back is measured. The formula is mass in grams divided by the current in amperes. A high BL figure indicates a very strong transducer that moves the cone with authority! Driver free air resonance, in Hz. This is the point at which driver impedance is maximum. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion.

If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'.

With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension surround and spider are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well.

The industry standard is to measure inductance at 1, Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes.

Maximum impedance Zmax occurs at Fs. The driver's effective mechanical mass including air load , in kg. The driver radiation mass load is the confusing part. In simple terminology, it is the weight of the air the amount calculated in Vd that the cone will have to push.

The suspension must prevent any lateral motion that might allow the voice coil and pole to touch this would destroy the loudspeaker. The suspension must also act like a shock absorber. Qms is a measurement of the control coming from the speaker's mechanical suspension system the surround and spider. View these components like springs. Qes is a measurement of the control coming from the speaker's electrical suspension system the voice coil and magnet.

Opposing forces from the mechanical and electrical suspensions act to absorb shock. Qts is called the 'Total Q' of the driver and is derived from an equation where Qes is multiplied by Qms and the result is divided by the sum of the same.

As a general guideline, Qts of 0. In your case, about 0. Using another calculator - LinearTeam For a single 2" diameter port, with a 9 liter cabinet, and a 69hz cabinet resonance, the port length now become a very workable 4.

So - 9 liter cabinet 8. Also, notice that the Speaker are rated at 4 ohms with a likely minimum impedance of 2. That mean at best, you will only be able to place one speaker on each amp channel. Speaker design is extremely complex, and what we have done here deals with only the most elemental aspects of it. Last edited: Jul 4, BlueWizard said:.

These are the actually numbers you want. Click to expand Sd Effective piston radiating area of driver, in square centimeters. Now the question is whether to partition the box and go with floor standers, or find some floor mounts Anyone know any decent online accessories stores preferably UK?..

For a single 2" diameter port, with a 9 liter cabinet, and a 69hz cabinet resonance, the port length now become a very workable 4. Hi BlueWizard, do you mean the port is tuned to 69Hz? Even in its most basic form gives great results. That would give you less distortion and more power handling ability.

PLUS, the speakers would be 8 ohms, and would work an virtually any amp. Just a thought. You must log in or register to reply here. Similar threads S. Hi, wall mounted speaker advice required! Rg Amplifier source resistance includes leads, crossover, etc. Basically, a rough measurement of what you can get away with in the house before your better half who usually controls the finances as well raises a fuss.

Sd Effective piston radiating area of driver, in square meters. SQ Sound Quality. A term that refers to a focus on accuracy and transparancy as opposed to a focus on how loud the speaker or system can get. Vas is one of the trickiest parameters to measure because air pressure changes relative to humidity and temperature — a precisely controlled lab environment is essential. Cms is measured in meters per Newton. Cms is the force exerted by the mechanical suspension of the speaker.

It is simply a measurement of its stiffness. Considering stiffness Cms , in conjunction with the Q parameters gives rise to the kind of subjective decisions made by car manufacturers when tuning cars between comfort to carry the president and precision to go racing.

Think of the peaks and valleys of audio signals like a road surface then consider that the ideal speaker suspension is like car suspension that can traverse the rockiest terrain with race-car precision and sensitivity at the speed of a fighter plane.

Vd Maximum linear volume of displacement of the driver product of Sd times Xmax , in cubic meters. Xmag Excursion limit due to the magnetic limitations of the driver's motor. Xmax Linear one-way travel of the cone.

Xmax is used to determine the maximum linear SPL capability of the driver, and can be defined in a number of ways. The DUMAX definition is objectively the best one, and it is defined as the shorter of the Xmag and Xsus values, in each direction of cone travel. This definition is more useful than the older definition of Xmax, which was solely dependent on the length of the voice-coil vs. Xmech Maximum physical excursion capability of the driver.

Exceeding Xmech normally results in damage to the driver. Excursion limit due to the driver's suspension. GlassWolf's Home. L length of wire immersed in magnetic field, in meters Lces The electrical inductive equivalent of Cms, in henries Le This is the voice coil inductance measured in millihenries mH.