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Question regarding SNR on amplifier input
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laejf:
Hi. I'm building a class D amplifier and have some questions about the input signal voltage level.

The raw audio signal voltage interval from my phone or computer is very low (at so called consumer line level(?)). To increase the signal to noise ratio (SNR) prior to the sampling I want to increase the voltage to work with my triangle-wave sampling signal of +-3.3V. How is this usually done? I could use automatic gain control to make the input to always vary between +-3.3V but then I won't be able to adjust the volume using the audio source. Another way could be to amplify the voltage to be between an interval, proportional to the interval of the raw signal but higher. Although, then the SNR will still be non-optimal at a low volume. Is there a go to-method of how this is done in a regular amplifier?

Thanks in advance.
Audioguru:
Audio amplifiers are built with low noise parts.
AGC ruins the dynamical range of music and is very noticeable.
laejf:

--- Quote from: Audioguru on February 18, 2019, 07:26:07 pm ---Audio amplifiers are built with low noise parts.
AGC ruins the dynamical range of music and is very noticeable.

--- End quote ---

Ok,  is there a standard input/sample-signal level ratio?
Audioguru:

--- Quote from: laejf on February 18, 2019, 07:49:44 pm ---Ok,  is there a standard input/sample-signal level ratio?

--- End quote ---
Sampling? Triangle wave? Are you trying to re-invent a class-D audio amplifier circuit? Buy an audio amplifier that uses a class-D amplifier IC instead.
laejf:

--- Quote from: Audioguru on February 19, 2019, 01:32:35 am ---
--- Quote from: laejf on February 18, 2019, 07:49:44 pm ---Ok,  is there a standard input/sample-signal level ratio?

--- End quote ---
Sampling? Triangle wave? Are you trying to re-invent a class-D audio amplifier circuit? Buy an audio amplifier that uses a class-D amplifier IC instead.

--- End quote ---

I'm trying to build one. If I bought one it wouldn't be much of a project now would it? Most class D amplifiers seem to use a triangle-wave to compare to the input signal in order to digitalize it. And my question is how they usually handle the input to be sampled optimally
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