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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.

Post Subject: DC vs AC OperationPosted by TonyB on: 12/8/2010

The differences between the battery operation and AC operation are to be expected.
One case is isolated (hopefully) from AC, the other case is not. If anybody thinks otherwise,
they are fooling themselves.

The first question to ask is to MAKE SURE that the battery is connected even when the
unit is running from AC.

If we are 101% sure (ideally by measurement of an open unit when it is operating) that
it is connected and that no switches between the battery and the regenerator were
changed between the battery and the AC modes operation, then the cause is the charging
circuit: it is connected in parallel with the battery in AC mode of operation.

There is a number of possible causes and a comparison of the schematics of the current
and previous versions would reveal the cause of the latest change in sound.

The reasons for the difference between the battery and AC operation could be:

- An extra capacitor after rectifiers is connected in parallel with the battery (it is not there in battery only operation)
- The rectifiers generate noise and pass it in both directions
- Rectification adds spikes/RFI/EMI to DC which are not there in DC operation
- The transformer passes noise form AC to rectified DC
- Caps on AC input
- Chokes on AC input
- Rectification may dump noise, ... into GND line
- and many others...

TonyB

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