Hello,
Could you please help in building a power supply for a noise sensitive audio preamplifier, powered from a laptop brick power supply (SMPS)?
My main amp is to be powered from the laptop brick power supply (19.5v), so thinking to draw power for the noise sensitive preamplifier from the same.
The preamplifier needs dual voltage supply +/- 10V.
What is the best way to use this SMPS supply (laptop PS):
1. Using positive and negative LDO to generate the +/- 10V from the 19.5v SMPS input. But most of the linear regulators have less PSRR at high frequency which we get from SMPS.
2. Using CLC filter, (parallel capacitor, series ferritte beads and next parallel capacitor) to filter SMPS noise, and then using positive and negative LDOs as above.
3. Using CLC filter as above and use resister divided positive and negative voltages.
Or any other better way to use SMPS to power the pre amplifier.
In general the pre amplifier was powered by a separate linear transformer based power supply. But I am thinking to use already available SMPS (which powers the main AMP) to power the preamplifier also, instead of again using a separate power supply.
thanks and regards
S Sarath