Hello,
I have here VSMD001 modules considering using them as an easy plug-in solution.
Feeding them to the relatively high gain amplifier when full line levels transfer to roughly 40W RMS output power with a sensitive horn speaker. Linear TDA based design, simple stuff.
When I have isolated power for the module and amplifier everything works nice and clean.
But when I connect power grounds I get audible noise and weak high frequency and slightly stronger clicks at RTOS loop rate.
I know I'm near the specified S/N ratio. As sound levels are over 110dB with this setup.
Can I get rid of this noise without expensive isolated power?
VS1000 Module Ground loop noise issues. CPU noise in audio.
Re: VS1000 Module Ground loop noise issues. CPU noise in audio.
Hi,
I'll try to guess some solutions an tactics to find the problem
Have you tried AC-couling? Adding capacitors to block DC from the audio. Oh and does the amplifier have differential input?
What kind of your setup is? Two lab powers, some amplifier board and VS1000 module on breadboard?
And where do you connect the gounds? on the power supply? Have you tried to connect grounds shortest possible path? What happens if you connect grounds for example with 100k resistor? Have you measured the voltage difference or current going between the boards?
The problem sounds like some current goes between the devises and the ground somehow sums it to signal.
This is VS1005 and 2x40W D-class amplifier: https://www.vlsi.fi/en/support/evaluati ... board.html You could find something usable by studying it.
Can you share schematics? It reduces my stupid question count dramatically.
I'll try to guess some solutions an tactics to find the problem
Are yout taking stereo out or just mono? If only mono is needed, you could try to take signal between left and right instead of left or right and gbuf.Miyuki wrote: ↑Fri 2022-02-25 16:39 Hello,
I have here VSMD001 modules considering using them as an easy plug-in solution.
Feeding them to the relatively high gain amplifier when full line levels transfer to roughly 40W RMS output power with a sensitive horn speaker. Linear TDA based design, simple stuff.
Have you tried AC-couling? Adding capacitors to block DC from the audio. Oh and does the amplifier have differential input?
What kind of your setup is? Two lab powers, some amplifier board and VS1000 module on breadboard?
As you probably know already, you have a ground problem. Are there other signals between VS1000 and the amplifier?When I have isolated power for the module and amplifier everything works nice and clean.
But when I connect power grounds I get audible noise and weak high frequency and slightly stronger clicks at RTOS loop rate.
And where do you connect the gounds? on the power supply? Have you tried to connect grounds shortest possible path? What happens if you connect grounds for example with 100k resistor? Have you measured the voltage difference or current going between the boards?
The problem sounds like some current goes between the devises and the ground somehow sums it to signal.
With high amplification even low noise becomes audible easily. But I believe it is possible to get much better from your description.I know I'm near the specified S/N ratio. As sound levels are over 110dB with this setup.
Can I get rid of this noise without expensive isolated power?
This is VS1005 and 2x40W D-class amplifier: https://www.vlsi.fi/en/support/evaluati ... board.html You could find something usable by studying it.
Can you share schematics? It reduces my stupid question count dramatically.
Re: VS1000 Module Ground loop noise issues. CPU noise in audio.
The Schematic is simple as shown. Using some GPIO with optocouplers and the mono signal.
When I use it as shown with isolated DC/DC it works just fine. It is on a small board with just what is on the schematics. But it behaves the same way on the breadboard.
When I replace DC/DC with 7805 and connect grounds at this point it ends up with noise.
That 12V input power is provided by the amplifier.
For now, it looks I will stick with an isolated DC/DC power
When I use it as shown with isolated DC/DC it works just fine. It is on a small board with just what is on the schematics. But it behaves the same way on the breadboard.
When I replace DC/DC with 7805 and connect grounds at this point it ends up with noise.
The main issue Amplifier is ground referenced. If it will be differential, it will be simple, just take it relative to gbuf shall be clean.Hannu wrote: ↑Tue 2022-03-01 13:57 Are yout taking stereo out or just mono? If only mono is needed, you could try to take signal between left and right instead of left or right and gbuf.
Have you tried AC-couling? Adding capacitors to block DC from the audio. Oh and does the amplifier have differential input?
What kind of your setup is? Two lab powers, some amplifier board and VS1000 module on breadboard?
That 12V input power is provided by the amplifier.
For now, it looks I will stick with an isolated DC/DC power
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Re: VS1000 Module Ground loop noise issues. CPU noise in audio.
I didn't notice anything problematic. As you said it is a simple circuit. Something makes a ground loop and noise comes to audible level.
What about UART cable? Has it been connected when you have tested? Could we blame computer being noisy?
Having the project on my table for a week and poking with different measurement instruments and adding random components, would make it work noiseless way. But if isolated DCDC is option for you, it's OK for me too
What about UART cable? Has it been connected when you have tested? Could we blame computer being noisy?
Having the project on my table for a week and poking with different measurement instruments and adding random components, would make it work noiseless way. But if isolated DCDC is option for you, it's OK for me too
Re: VS1000 Module Ground loop noise issues. CPU noise in audio.
UART was used just for programming
and it just settled down to use that isolated DCDC and I do not want to see it again
and it just settled down to use that isolated DCDC and I do not want to see it again