| Electronics > Beginners |
| virtual ground in multiple output amplifiers |
| (1/1) |
| kokodin:
I post it here because i am just embaresed that i don't know it situation is simple: single power suply, ground at 0V and positive rail at 24V i was thinking about making 4 tda2030 output stages for 4 separate 4 ohm speakers ~10W each i made first power stage, tested it, and i begin to think. can i use virtual ground from this power stage to bias other 3 or should i make 4 separate resistor deviders to bias each tda chip biasing as its own thing? not that i want save 2 resistors per chip, but i was wondering how much would single common virtual ground drift and distort inputs offor instance silent at this moment channel? |
| paulca:
Take a look at my recent thread "Circuit Review?" before committing to the resistor only based v-ground. It has serious draw backs. There is a link to literally dozens of designs for v-ground circuits for when you need much more power handling. If the v-ground is stable enough I would expect it would be fine for biasing multiple outputs. Mine does two. A few tests I would do.... connect your circuit to a noisy power source, or power something noisy and digital from the same power source as your amp. I found I got a lot of noise pick up with the resistor only divider. The other is to measure the v-ground with a scope in AC coupling mode to see how much drift you have at high power outputs. Personally I take that as a percentage of the full output and subjectively determine if it's good enough. So 10mVpp drift outputing 10Vpp is 0.1% and fine. 100mV is 1% and probably too much. |
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