CM6502B Datasheet, PDF (19/40 Pages) C-Media Electronics – USB Audio Sound Chip

CM6502 / CM6502B
USB Audio Sound Chip
EEPROM programming.
PCM
Digital
Attenuation
PCM
Digital Equalizer
(5-Band Fc, Gain,
Bandwidth, OPA Gain)
Digital-Analog
PCM _-Converter Analo
Analog
Analo
g
The EQ engine contains 5 frequency bands (Fc) of digital filters to conduct transfer functions of the
frequency response over the audio band. It allows maximum +-12dB digital gain (Gain) for each band with
0.5dB adjustment per step. Each filter will have its bandwidth (BW) factor between 0 and 1.0.
Fc: Center Frequency, F1~F5, 20<Fc<20K (Hz)
Gain: Digital Frequency Gain, -12dB <= Gain <=+12dB, 0.5dB/step
BW: Filter Bandwidth Factor, 0<BW<1
OPA Gain: Analog Gain Compensation setting for each equalizer mode
The EQ engine already provides 4 preset modes/settings based on the same preset F1~F5 center
frequencies and OPA gain:
F1 (Bass)= 100Hz
F2 = 350Hz
F3 = 1KHz
F4 = 3.5KHz
F5 (Treble) = 13KHz
With the 4 preset EQ modes, customers could use EEPROM parameters to change the gain values for each
band of the center frequency and hence customize the 4-preset EQ curves based on the preset center
frequencies and bandwidth. Alternatively, customers could also skip the 4 preset modes and create a
customized EQ curve by changing the center frequencies, gain values and even the bandwidth factors in
EEPROM parameters to make the headphone sound better or meet some frequency requirements.
However, in this case, the product will always use one optimized EQ setting and could not allow users to
dynamically change among different preset modes. Customer could also consider reporting Treble/Bass
feature unit by EEPROM to Windows UAA driver to allow end-users to adjust Bass (F1) and Treble (F5) by
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Rev. 1.02 ︱ Page 19