Lumped parameter model loudspeaker parts

Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Klippel , Joachim Schlechter Published Engineering Journal of The Audio Engineering Society The mechanical vibrations of loudspeaker drive units are described by a set of linear transfer functions and geometrical data which are measured at selected points on the surface of the radiator cone, dome, diaphragm, piston, panel. These distributed parameters supplement the lumped parameters Thiele-Small, nonlinear, thermal parameters , simplify the communication between cone, driver, and loudspeaker system design, and open new ways for loudspeaker diagnostics.

===

We are searching data for your request:

Lumped parameter model loudspeaker parts

Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Content:

• Oh no, there's been an error
• Measurement and Perception of Regular Loudspeaker Distortion
• EN 60268-5:2003
• Distributed Mechanical Parameters of Loudspeakers Part 1: Measurements
• A computationally efficient hybrid 2D–3D subwoofer model
• AES E-Library
• End-Of-Line Testing
• Engineering Acoustics
• Small Signal Lumped Parameters

WATCH RELATED VIDEO: Lumped Parameter Circuits and Nodes

Oh no, there's been an error

While this subject has been thoroughly explored, I will present my contribution in the form of an online calculator that will easily do the calculations for you.

The article will show how the model is derived and some of its uses. Loudspeaker enclosure can also be added in the model and investigate the effects they have on the overall impedance that is present at the loudspeaker terminals. This will give us some insights into the advantages and limitations the model has. In a driver we can clearly identify 3 sections corresponding to electrical, mechanical and acoustical domains and 2 energy conversions, from electrical to mechanical domain and from mechanical to acoustical domain respectively.

Figure 1. The voice coil has a dc resistance property which is given by wire material, diameter and length. The magnetic circuit has also a contribution on , first by creating a ferrous core and second from eddy currents that form in the steel around the voice coil. This complicates things as the semi-inductance can not be easily modeled using lumped elements and it is not something that can be derived from fundamental properties of the driver.

Some manufacturers do publish parameters that help model this but it is quite rare and many models are creating via curve matching technique which requires impedance measuring capabilities. For this reason the semi-inductance is not modeled in this online calculator.

The magnetic circuit creates a static magnetic field in the gap with a flux density. The product between magnetic flux density and voice coil wire length is often called the motor force factor and it is basically the coupling factor between the electrical side and the mechanical side.

The force exercised on the voice coil is equal to with being the electrical current through the voice coil. We can see the coupling between the electrical side and mechanical side is therefore represented by a gyrator because we make the analogy that velocity corresponds to electrical current and force corresponds to voltage. This is referred to as impedance analogy. If we think in terms of efficiency, than we would like to generate as much force from electrical current as possible by having a large coupling factor.

On the mechanical side, fundamental properties such as mass and compliance are described as lumped electrical components such as resistor, inductor and capacitor. First we have the total mass of the moving elements such as the cone, dust cap and voice coil combined with the contribution to the moving mass by the spider and surround and finally the mass of the air load around the cone.

This mass is represented by inductance. Some papers treating this subject do not include the air load mass on the mechanical side and such they note the total mass as. While this makes sense, it is not often used. Why is mass an inductance? There are two basic electric elements that can store energy, the inductance and the capacitance. For instantaneous values we can say:.

Replacing and with their electrical analogues and we get:. The losses of the suspension system are shown as resistance. This is determined by the materials and geometry of the voice coil former, spider and surround. On the mechanical side we can see a resonant circuit being formed by and with and resistance acting as damping. I find it important to mention that above the resonant frequency , for most of the bandwidth, the output of the driver is controlled by the mass. In terms of efficiency it is desirable to have a large cone as long as the mass does not increase.

Depending on its geometry part of the surround surface also contributes to the total area. On the acoustical side, in figure 1, we have a generic impedance element. This corresponds to the radiation resistance for both front and back of the cone and the enclosure impedance. If no enclosure is modeled we would only keep the radiation resistance and treating the cone as pulsating half sphere, we can define as:.

As can be seen in equation 4, is non-linear and depends on frequency and thus it cannot be modeled using lumped elements. Figure 2 plots the value of the radiation resistance on the acoustical side as and after transformation to the mechanical side as. Values of are quite small and we can neglect its influence especially when is much higher.

The transformation from acoustical side to mechanical side is straight forward:. If we would use instead of on the mechanical side then we should include the air mass around the front and back of the cone as inductors. Figure 3 shows the electrical circuit equivalents for closed and vented enclosures. With a closed enclosure the air inside acts as a compliance and thus it is modeled as a capacitor and is defined by equation 6.

If the enclosure is not air tight some of the air will leak. These losses are modeled as a resistor whose value depends on the parameter. This air acts as a mass because it will move back and forth as the cone vibrates unlike the air inside the enclosure who is elastic compressing or rarefying under force and recovering when the force is removed.

To study the electrical impedance it would make sense to move all the elements on the electrical side and then apply circuit theory. The transformation from the acoustical side to mechanical side is defined by the following equation:.

The transformation from the mechanical side to electrical is a little bit more complicated due to the gyrator. It will convert series circuits to parallel circuits and vice-versa and it will convert inductors to capacitors and vice-versa. Figure 5 shows the equivalent electrical circuit with all elements transferred on the electrical side.

The formulas for the conversion are listed below:. With no gyrators or transformers in our circuit we can easily calculate the impedance presented at the generator. Using a tool such as LTSpice we can create the above circuit and define our desired simulation. To get the impedance presented at the generator we should define an ac simulation and plot.

Analytically, we can brake the circuit and deal with groups of parallel or series connections one at a time.

Expressing the result in Cartesian form we get the following:. Let say this loudspeaker will be in a vented box with a volume of liters, a vent of 50 mm in length and 70 mm in diameter. The online calculator will provide the values for all the components in the circuit. All we need to do now is to build the circuit in LTSpice and run an ac simulation.

To get the impedance curve in figure 7, we will plot. The resultant curve is the familiar vented loudspeaker impedance. We can continue our analysis for example by stepping any component value from the circuit and see how the impedance is affected. This can be achieved by adding a directive in LTSpice and defining the min, max and interval parameters. The result in figure 8 shows how we can easily check the enclosure volume for our desired LF alignment.

Another use is to help design crossover sections. As can be observed in figure 9 our crossover section is made up of inductor and capacitor. We can use again to simulate the response with different values for and. This semi-inductance is very hard to model using lumped elements and has been the subject of some debate.

We will address it in future articles. I know the paper you are referring to but I quit AES a couple of years ago so I cant help you with that. I did not include that model because all semi-inductance models are derived from measured impedance not from physical properties of the driver. I am working on finding a model that will include semi-inductance behavior based on physical properties. I do have a question. Did I misunderstand something?

The acoustical impedance unit is Rayls. I wonder if after converting components from acoustic side to mechanical side, the component units become mechanical-based unit, and after converting to electrical side, all components have electrical units H, F, Ohm? For SPL curve a different kind of transformation is needed.

I will need to detail that in a followup article. Your email address will not be published. It should be noted that this entire article refers to dynamic loudspeaker drivers only. Loudspeaker driver model. Figure 2. Figure 3.

Loudspeaker Enclosure Model. Figure 4. Converting components from acoustical side to mechanical side. Figure 5. Converting components from mechanical side to electrical side. Figure 6. Speaker Equivalent Electrical Circuit. Figure 7. Loudspeaker LTSpice Simulation.

Figure 8. Parameter Step in Loudspeaker Simulation. Figure 9. Low Pass Filter Simulation. Figure Simulated vs Real Loudspeaker Impedance. Best Regards, Riccardo.

Measurement and Perception of Regular Loudspeaker Distortion

Assembly Line - Theory and Practice. Testing a manufactured unit at the end of the assembly line is a critical step in the production process. Defective products or even those not matching specification limits closely enough must be separated from the functional units shipped to the customer. End-of-line testing assesses not only the quality of the product, but also the stability and yield of the production process.

EN 60268-5:2003

To browse Academia. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Engineering Acoustics. A short summary of this paper. Edition 1.

Distributed Mechanical Parameters of Loudspeakers Part 1: Measurements

Online speaker building calculators by Hi-Fi Speaker Design. We highly recommend this website. Download the ScanSpeak Toolbox Excel spreadsheet. Scan-Speak now provides advanced parameters on their driver data sheets.

A computationally efficient hybrid 2D–3D subwoofer model

The Audio Voice Newsletter. Show more 8. Show less. This article discusses the physical causes of regular loudspeaker distortions, their modeling by using lumped and distributed parameters, the objective assessment using modern measurement techniques, and the perception by the human ear. Article originally published in Voice Coil, May

AES E-Library

An unconventional type of electrostatic loudspeaker is presented in this paper. The loudspeaker made of thin, light, and flexible electret material lends itself well to the space-concerned applications. Electrical impedance measurement reveals that the coupling between the electrical system and the mechanical system is weak, which renders conventional parameter identification based on electrical impedance measurement impractical. A different approach is thus employed to model the electret loudspeaker. To predict the loudspeaker's dynamic response, finite-element analysis FEA is conducted on the basis of a simple model and a full model. In the simple model, FEA is applied to model the electret membrane, leaving the rest of system as rigid parts. In the full model, FEA is applied to model the entire membrane-spacer-back plate assembly. Velocity response of the membrane subject to a uniformly distributed force is calculated using FEA harmonic analysis.

End-Of-Line Testing

Gives the characteristics to be specified and the relevant methods of measurement for loudspeakers using sinusoidal or specified noise or impulsive signals. IEC specifies methods of measurement for the electrical impedance, sensitivity, directional response pattern, dynamic range and external influences of sound system microphones, and also details the characteristics to be specified by the manufacturer. It applies to sound system microp

Engineering Acoustics

RELATED VIDEO: Solution for a loudspeaker model

This is a model of a moving-coil loudspeaker where a lumped parameter analogy represents the behavior of the electrical and mechanical speaker components. The Thiele-Small parameters small-signal parameters serve as input to the lumped model, which is represented by an Electric Circuit physics. The lumped model is coupled to a 2D axisymmetric Pressure Acoustics model describing the surrounding air domain above and below the speaker cone. The output from the model includes, among many things, the speaker sensitivity, the impedance, and the radiated acoustic power. The results are compared with an analytical solution based on the flat piston approximation. This model example illustrates applications of this type that would nominally be built using the following products:.

Small Signal Lumped Parameters

Voice Coil Impedance as a Function of Frequency Voice Coil Impedance as a Function of Frequency and. Recent work by Klippel [1] and Voishvillo [2] h as shown the significance of voice coil inductance in respect to the. In such work the methods used to derive distortion require the inductance to. A new. The complex. Results show that the impedance model requires that its parameters vary independently.

Ref document number : Country of ref document : EP. Kind code of ref document : A1.