| TJ |
| hi, i like some expert can give me some answer for this questiions !! why the output voltage not stay at 0 volt ?in this circuit it stay at +20v ! how it work ? |
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| hacknet |
| i guess thats because it is supposed to work in balanced mode. on idle, the both 20v are the same potentials and thus is safe for the driver.;) |
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| stefanobilliani |
| It is just that the speaker does not see any voltage , and it is indifferent to it where the absolute voltage of the drains are ; the drain voltages just have to be equal . |
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| TJ |
| i still confuse ! if we not talk about impedance, gain distortion ...etc ... that meant we can direct connect output to the speaker from a ... differential amplifier .... or phase splitter ! and i right ? |
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| stefanobilliani |
| quote: | Originally posted by TJ
why the output voltage not stay at 0 volt ?in this circuit it stay at +20v |
No! The output is differential and stays at O volt.
Of course the +20 volts are not arbitrary , and set for best performance .
For your last question I think you are right.
:cool: |
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| TJ |
thank ! i got another questions / eq tion i not sure right or wrong !! hope u guy help me solve !! im calculate the output transformer base on the voltage and output from the circuit zvr7T and im not sure is correct or not ............
From the circuit we know that 30v is the max audio voltage , since transformer waste power i decreace 10% on it . ~27v/1.414 = 19V rms . this circuit is design for 30w into 8 ohm then voltage =15.5v , turn ratio = 19/15.5 = 1.225 , primary Z = 8 * 1.225 = 9.8 . 9.8* 4 = 39.2 ohm !! so the transformer for this circuit will be ~ 40 ohm center tapped ? correct or not ? |
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| Nelson Pass |
Well, the transformer says 8 ohms on the four primary windings,
and 80,000 ohms on the secondary which gives 50 to 1 if you
series all the primaries to 32 ohms.
The amp does 30 volts rms into these in series, which produces
50 X this voltage, which is 1500 V RMS. The loss in the
transformer is very slight at mid band, as electrostatic panels
don't load it until the top octave or so.
In your calculation, you are assuming a 30V peak, but remember
that this circuit can swing quite a bit more than rail voltage. |
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