Hey,
Actually I'm wondering about the control strategy behind MUSES72323 and how others use it in their amplifiers. I’m designing an amplifier and currently writing my source code in C and I’m dealing with the volume and gain control in parallel. My first approach was to start with a gain of 0 and increase it each time the volume control reaches its limit till maximum gain is achieved. This means I have to find the right thresholds. After some thoughts I’m not sure about this control strategy or what idea the manufacturer had in mind. Maybe the recommended way is to use only one gain setting depending on the circuit and amplifier and control the volume only by the input divider? On the other hand, it makes sense to use the input divider preferred at maximum range, because I don’t like to divide to low values and amplify back to high levels.
How do you use the IC? Is it wise to use the full dynamic range or choose the gain only once and control the volume only with the input divider? Have you calculated the right thresholds and what are your experience? At the moment I'm writing the code and can't do measurements. Maybe it's also bad for the sound to switch the gain in active mode?
Thank you very much for your thoughts and hints.
Actually I'm wondering about the control strategy behind MUSES72323 and how others use it in their amplifiers. I’m designing an amplifier and currently writing my source code in C and I’m dealing with the volume and gain control in parallel. My first approach was to start with a gain of 0 and increase it each time the volume control reaches its limit till maximum gain is achieved. This means I have to find the right thresholds. After some thoughts I’m not sure about this control strategy or what idea the manufacturer had in mind. Maybe the recommended way is to use only one gain setting depending on the circuit and amplifier and control the volume only by the input divider? On the other hand, it makes sense to use the input divider preferred at maximum range, because I don’t like to divide to low values and amplify back to high levels.
How do you use the IC? Is it wise to use the full dynamic range or choose the gain only once and control the volume only with the input divider? Have you calculated the right thresholds and what are your experience? At the moment I'm writing the code and can't do measurements. Maybe it's also bad for the sound to switch the gain in active mode?
Thank you very much for your thoughts and hints.
Input preset gains are designed to be seldom changed once set up. The main volume/fader pot is used for everyday control. This is why volume has 256 steps of 0.25dB each and zero-crossing synch, whereas input gains are 3dB steps. Just like a mixing desk, the presets are set to allow good use of headroom and equalize different source levels.
So you'd probably want in your code to have a preset value for the input gains for each source, which is used when sources are switched. Volume would be separate independent control.
So you'd probably want in your code to have a preset value for the input gains for each source, which is used when sources are switched. Volume would be separate independent control.
Thank you very much. Yes, that makes sense. Do you have experience if changing of gain will generate audio disturbance?
With this control strategy, it would be a noise benefit to set gain with fixed resistors, if possible?
With this control strategy, it would be a noise benefit to set gain with fixed resistors, if possible?
The zero-crossing facility of the chip is designed to minimize zipper-noise when the gain is varied, but the 0.25dB steps are too big to eliminate zipper noise completely I suspect.
After some further investigation I can confirm, that you can hear the zipper-noise mentioned by @Mark Tillotson. In my test setup I switched from minimum to maximum gain and reduce the volume accordingly and you can definitively hear it. But it’s not that critical so it may be an option, to set gain and volume control in parallel to reduce SNR.
two my tested projects with 72323 + Arduino and ESP32: https://www.patreon.com/posts/2-varianta-nano-85783422