I'm doing some "empirical work", at least for myself, on this one. old TDA1541A dac.
Among other things then piggybacking (link above) i want some shares about how big the I/V resistor can be if you compensate with injection of a CCS ?
I am in the measuring stage now but would easylie accept other members work on this issue.
With the chips piggybacked I have only 12 ohm as I/V for the moment (gives 2.3V RMS -0dB sinevawe), but what will the figures be if i use a less sensitive tube (less amplifying) and use a larger I/V resistor, still compensating the DC imbalance with the CCS circuit?
Among other things then piggybacking (link above) i want some shares about how big the I/V resistor can be if you compensate with injection of a CCS ?
I am in the measuring stage now but would easylie accept other members work on this issue.
With the chips piggybacked I have only 12 ohm as I/V for the moment (gives 2.3V RMS -0dB sinevawe), but what will the figures be if i use a less sensitive tube (less amplifying) and use a larger I/V resistor, still compensating the DC imbalance with the CCS circuit?
I'm beginning to catch up by learning more and more trough my own measurings.
The answer to the above question is Yes. You can have a much larger resistor if you inject current so that the DAC only see 0 Volt at it's output.
There is a also another member here that discovered the same and recently posted in the thread: Building the ultimate NOS DAC using TDA1541A -ecdesign- and post #3063
To a degree then the THD starts
My measuring research today showed someting that I have mentioned in the thread above.
There is in fact a limit for the I/V resistor value. For a TDA1541A it's safe with 66 ohm. At 100 ohm you start to measure distortion (-0dB testsignal) and maybe also hear it in the music.
I havent tried 82 ohm (standard value)
Read my comments in the thread above at post #3076.
Another thing ... again. The recomended CCS injection, so that the TDA1541A just see 0V at it's output, is most notisable on the last bits ie the silent passages, where THD greatly can be reduced.
My measuring research today showed someting that I have mentioned in the thread above.
There is in fact a limit for the I/V resistor value. For a TDA1541A it's safe with 66 ohm. At 100 ohm you start to measure distortion (-0dB testsignal) and maybe also hear it in the music.
I havent tried 82 ohm (standard value)
Read my comments in the thread above at post #3076.
Another thing ... again. The recomended CCS injection, so that the TDA1541A just see 0V at it's output, is most notisable on the last bits ie the silent passages, where THD greatly can be reduced.
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