Measurement.
Basic amplifier measurements were made using the Focusrite Scarlett 2i2 2gen audio interface. 24 bit, 192kHz sampling was used. Laptop audio interface. Audiotester, ARTA, STEPS and RMAA programs were used in the Windows 10 21H1 64-bit environment.
The load of the amplifier were power cemet resistors with a resultant resistance of 8.3Ω. Parallel to these resistors are resistive voltage dividers with an RC filter suppressing the residual frequency of the power stage keying.
The waveforms obtained are the result of measuring both the amplifier and the audio interface itself. I do not include measurements of the audio device itself. Ultimately, the real performance of the amplifier is slightly better than given below.
The first graph is the sweep frequency response.
The second and third graphs are the harmonics distribution for 0dB and -20db levels (blue line only).
The fourth graph shows the inter-channel crosstalk.
The fifth graph shows the noise and distortion level relative to the 0dB level. Note - the tested amplifier was not enclosed in a scanned housing, the constant noise 50Hz, 100Hz, 150Hz ...
The sixth plot shows the intermodulation distortion at full undistorted power output.
The seventh graph shows the measurement of the passband using the multitone method.
The eighth last graph is the frequency response of nonlinear distortions with additional breakdown into second to sixth harmonics. Measurement for -3dB level.
For passband measurements - output impedance os signal source is less than 1 kilohm!.
The supply voltage at full output was 23.9V.
The RMS output voltage of the sine for the adopted maximum power point without distortions, i.e. the conventional 0dB, is 15.2V (28W on 8Ω). It has an RMS voltage of 130mV at the input. For the commercial level, i.e. 316mV, this is a 6dB additional margin of the input sensitivity.
Basic amplifier measurements were made using the Focusrite Scarlett 2i2 2gen audio interface. 24 bit, 192kHz sampling was used. Laptop audio interface. Audiotester, ARTA, STEPS and RMAA programs were used in the Windows 10 21H1 64-bit environment.
The load of the amplifier were power cemet resistors with a resultant resistance of 8.3Ω. Parallel to these resistors are resistive voltage dividers with an RC filter suppressing the residual frequency of the power stage keying.
The waveforms obtained are the result of measuring both the amplifier and the audio interface itself. I do not include measurements of the audio device itself. Ultimately, the real performance of the amplifier is slightly better than given below.
The first graph is the sweep frequency response.
The second and third graphs are the harmonics distribution for 0dB and -20db levels (blue line only).
The fourth graph shows the inter-channel crosstalk.
The fifth graph shows the noise and distortion level relative to the 0dB level. Note - the tested amplifier was not enclosed in a scanned housing, the constant noise 50Hz, 100Hz, 150Hz ...
The sixth plot shows the intermodulation distortion at full undistorted power output.
The seventh graph shows the measurement of the passband using the multitone method.
The eighth last graph is the frequency response of nonlinear distortions with additional breakdown into second to sixth harmonics. Measurement for -3dB level.
For passband measurements - output impedance os signal source is less than 1 kilohm!.
The supply voltage at full output was 23.9V.
The RMS output voltage of the sine for the adopted maximum power point without distortions, i.e. the conventional 0dB, is 15.2V (28W on 8Ω). It has an RMS voltage of 130mV at the input. For the commercial level, i.e. 316mV, this is a 6dB additional margin of the input sensitivity.
