EQ correction for source device impedance and output device impedance interactions
A software-based equalization method corrects for effects of impedance interactions of a source device and an output device, on an aggregate frequency response, in audio playback of a system. The correction results in perceived sound remaining consistent from any source device and output device combination. The method does not require any hardware modifications and a cloud-based database of source devices and output devices provides corrections for a wide array of possible device pairings.
1. A method for correcting interactions between source device and output device impedances, the method comprising:
measuring the complex impedance of the source device;
measuring the complex impedance of the output device;
determining the frequency response of the interaction between the source device and the output device based on the measured impedances by modeling the frequency response of the interaction between the source device and the output device as a frequency-dependent voltage divider;
generating an inverse equalization of the frequency response;
applying the inverse equalization to a signal processed by the source device to produce a processed signal;
providing the processed signal to the output device; and
transducing the processed signal into sound waves by the output device.
2. The method of claim 1 , wherein determining the frequency response of the interaction between the source device and the output device based on the measured impedances comprise determining the frequency response V out (f) using an equation:
V
out
(
f
)
=
Z
output
device
(
f
)
Z
output
device
(
f
)
+
Z
source
device
(
f
)
V
i
n
(
f
)
3. The method of claim 1 , wherein the source device is a smartphone.
4. The method of claim 1 , wherein the inverse equalization is stored in the source device.
5. The method of claim 1 , wherein the inverse equalization is stored in a database including a library of inverse equalizations for a multiplicity of source and output device pairings provided to uses as needed.
6. The method of claim 4 , wherein the database is a cloud-based database.
7. The method of claim 1 , wherein applying the inverse equalization to a signal processed by the source device comprises applying the inverse equalization to a signal in the source device.
8. The method of claim 1 , wherein applying the inverse equalization to a signal processed by the source device comprises applying the inverse equalization to a signal before providing the signal to the source device.
9. A method for correcting interactions between source device and output device impedances, the method comprising:
measuring the complex impedance of the source device;
measuring the complex impedance of the output device;
modeling the frequency response of the interaction between the source device and the output device as a frequency-dependent voltage divider;
generating an inverse equalization of the frequency response;
applying the inverse equalization to a signal processed by the source device to produce a processed signal;
providing the processed signal to the output device; and
transducing the processed signal into sound waves by the output device.
10. A method for correcting interactions between source device and output device impedances, the method comprising:
measuring the complex impedance of the source device;
measuring the complex impedance of the output device;
modeling the frequency response of the interaction between the source device and the output device as a frequency-dependent voltage divider using the equation:
V
out
(
f
)
=
Z
output
device
(
f
)
Z
output
device
(
f
)
+
Z
source
device
(
f
)
V
i
n
(
f
)
generating an inverse equalization of the frequency response;
applying the inverse equalization to a signal processed in the source device to produce a processed signal;
providing the processed signal to the output device; and
transducing the processed signal into sound waves by the output device.