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-   -   voltage regulation for input buffer in UcD (http://www.diyaudio.com/forums/class-d/88333-voltage-regulation-input-buffer-ucd.html)

zilog 15th October 2006 07:32 PM

voltage regulation for input buffer in UcD
 
In my variant of UcD, the input buffer op-amp is being fed by voltage that comes directly from the switching rails, and has undergone filtration through a LC combination of 0.47 mH/220u followed by BD139/BD140 zener followers to lower the voltage to +-23V, and at last a 7815/7915 combo. This construction gives quite good stable and noise-free voltage for the NE5532, but it is huge and uses board space I do not have.

What I wonder is how much switching noise suppression must I use to feed my NE5532 +-15V taken from the switching rails that are between +-30 - +-50V. The goal is to get voltage that is stable enough not to impact the sonic performance of the amplifier, but at the same time avoid over-engineering this part by giving it unnecessarily clean power. Would be preferrable to find a solution that doesnt require cascading of steps either.

BWRX 15th October 2006 11:24 PM

You can just do away with the 7815/7915 regulators. The older UcD180 modules use 2097/2222 zener followers to derive the supply rails for the AD8620. The newer ones probably do too, but I don't have a new one to look at so I can't say for sure.

zilog 16th October 2006 01:05 PM

Quote:

Originally posted by BWRX
You can just do away with the 7815/7915 regulators. The older UcD180 modules use 2097/2222 zener followers to derive the supply rails for the AD8620. The newer ones probably do too, but I don't have a new one to look at so I can't say for sure.

Do you know if the UcD180 uses LC-filtering before the zener followers?

BWRX 16th October 2006 04:48 PM

There is only a small ceramic cap in parallel with the zener, effectively forming an RC filter with the biasing resistor. There doesn't appear to be any other filtering.


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