Hi guys! I assembled this DAC, it sounds good, but I would like to slightly increase the output voltage to 2 volts (my old rotel amplifier has a sensitivity around 2 volts), I would not want to use the operational amplifier, is there an elegant circuit on 1 transistor?
resistors approx. 1 kohm
resistors approx. 1 kohm
If you only need 2V peak then that's possible without an external transistor. What supply voltage are you using for the TDA1543? It can go up to 8V I believe.
I am currently using 6 volts.
Will the resistance need to be increased to increase the voltage? Will this lead to more distortion
Will the resistance need to be increased to increase the voltage? Will this lead to more distortion
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Yes you'll need a higher I/V resistor to get more voltage swing, given the current's fixed from the DAC chip. Whether this leads to more distortion depends on the loading at the DAC's output. You can always parallel DAC chips to reduce the output impedance.
please take a look at this page:
Dave Kimber's audio pages - TDA1543 passive I/V resistors
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Other thing is that when You "convert" current to voltage using passive Riv, the voltage is in opposite phase (-180deg) at the output of DAC. This can be corrected with inverting DATA digital line. And the voltage after Riv will be in phase.
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One solution is to employ very low amplification factor tube for additional low amplification needed AND shifting the phase to 0deg back to the output of the dac.
For instance 12B4, 12B4-A, 6082A etc. These vacuum tubes has amplification factor of 2, but in circuit -A (negative gain is to indicate phase shift...) will be less than mju. So You can expect not more than +6db from this low-mju stage. BUT bare in mind that is almost double voltage P-P.
Cheers 🙂
Dave Kimber's audio pages - TDA1543 passive I/V resistors
.
Other thing is that when You "convert" current to voltage using passive Riv, the voltage is in opposite phase (-180deg) at the output of DAC. This can be corrected with inverting DATA digital line. And the voltage after Riv will be in phase.
.
One solution is to employ very low amplification factor tube for additional low amplification needed AND shifting the phase to 0deg back to the output of the dac.
For instance 12B4, 12B4-A, 6082A etc. These vacuum tubes has amplification factor of 2, but in circuit -A (negative gain is to indicate phase shift...) will be less than mju. So You can expect not more than +6db from this low-mju stage. BUT bare in mind that is almost double voltage P-P.
Cheers 🙂
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