power supply from one secondary

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AFAIK there is no problem with dual rails from a single secondary. The quality however is not very good.


/UrSv
 

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A few extra precisions as the QUAD schematic is fairly non-standard :
The center point is generated by R28-R29, amplified by T11-T12-R30-R31(a unity-gain buffer), and C10-C11 are the filter capacitors. As you can see, there is NO center point on the secondary of the transformer. The buffer must have the DC current capability for the bias and feedback, but not for the load, which sees the two filter capacitors in parallel connected to the center point(Thevenin equivalent circuit). I think this circuit must be wired with special care for current returns...
The project32 (i think) from ESP pages is based on the same idea for lower voltages, and a Texas Instrument chip TLE2426 does the same job.
 
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As long as you aren't pumping a lot of current through the
load as with a (non-balanced) power amp, you can do well
with forming a voltage divider with two equal value power
resistors and putting them across the supply. Where they
join is the new virtual ground, and you put a big fat cap
from there to the real ground. Voila!

:Popworm:
 
Since output stage of AlephX doesn't use and need the ground as such, would it be preferable to place filter caps directly across both rails (especially if they are lower in voltage) and use virtual ground only for the input stage. Any gains of such an approach?. It has been talked before, but nobody really gave a clear answer.
 
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