# April 2019 StudentZone Quiz Solution

Question:

Based on your measured data extract the L C and R for the speaker electrical model shown in figure 1 for the speaker you used. You can measure Rdc with the DC ohmmeter tool. Ignore LINPUT as it will be small compared to L. Enter these values into a circuit simulation schematic of the model and generate a frequency response sweep from 50 Hz to 1000 Hz and compare your model to the data you measured in the lab.

Consider the plot of the calculated impedance: We can extract from the plot the following information:

• Fs ~ 330Hz
• BW ~ 40Hz
• Rdc ~ 8Ω (see impedance value when frequency tends to 0Hz)
• R ~ 8Ω (at resonance Rdc + R ~ 18Ω)

Next, we can compute the values for L and C:

At resonance XL=Xc, therefore:

Now, simulate the circuit with the computed values:

The plot of the calculated impedance can be computed using the formulas provided in the article.

As expected, the frequency response values are closer to the ideal ones.

Consider the plot of the calculated impedance:

We can extract from the plot the following information:

• Fs ~ 330Hz
• BW ~ 40Hz
• Rdc ~ 8Ω (see impedance value when frequency tends to 0Hz)
• R ~ 8Ω (at resonance Rdc + R ~ 18Ω)

Next, we can compute the values for L and C:  At resonance XL=Xc, therefore: Now, simulate the circuit with the computed values: The plot of the calculated impedance can be computed using the formulas provided in the article. As expected, the frequency response values are closer to the ideal ones.