Ok, there has been some discussion regarding digital volume controls. There is naturally a degree of audiophile nervosa on the the subject. To this end I purchased a high quality Alps log 100k analogue pot and bashed together a volume control box. The idea to compare the signals to digital volume control. I havent had time to do what I intended, but a very quick and dirty comparison is below. Please dont regard this as anything definitive, more to provoke discussion. This really needs to be done on Amirs APx555.
Just for fun, you tell me which are the analogue volume, and which are the digital volume plots.
I generated a signal in Adobe Audition. It consisted of 5 sine tones at 1kHz, 4.3kHz, 5.8kHz, 8.2 kHz and 10.05kHz. The 1kHz was at about -45 dBFS and each subsequent tone reduced in level by a further 10dB. The reason for startin g at a low level was to ensure that the DAC harmonic distortion was already below the noise floor so as not to cause any confusion. Measurements were then taken at reducing 10 dB levels (it was a challenge to get the pot precisely adjusted) until the lowest signal disappeared into the noise floor (about a further -60dB attenuation.). Oh btw, 20 dB of gain was added in the measurement input to try and keep the dac noise floor above that of the measurement system. I will show 20dB steps to reduce the number of plots.
Volume control type A
Volume control type B
Just for fun, you tell me which are the analogue volume, and which are the digital volume plots.
I generated a signal in Adobe Audition. It consisted of 5 sine tones at 1kHz, 4.3kHz, 5.8kHz, 8.2 kHz and 10.05kHz. The 1kHz was at about -45 dBFS and each subsequent tone reduced in level by a further 10dB. The reason for startin g at a low level was to ensure that the DAC harmonic distortion was already below the noise floor so as not to cause any confusion. Measurements were then taken at reducing 10 dB levels (it was a challenge to get the pot precisely adjusted) until the lowest signal disappeared into the noise floor (about a further -60dB attenuation.). Oh btw, 20 dB of gain was added in the measurement input to try and keep the dac noise floor above that of the measurement system. I will show 20dB steps to reduce the number of plots.
Volume control type A
Volume control type B
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