Hello DrBarmental,
Congratulations, you have done a very good job !
The PCB design looks great.
I'm very happy to see that my previous work has inspired others DIYers.
And you seem to have more finished your work than me !
I still hope to be able (a day) to continue my previous work on the OSVA,
even if my personal life don't permit it for now or only for short time to time...
I will look in depth your remarks about your designs issues, and will follow
of course your own progress on this project.
One question about your THD measurement, you seem to have calibrated
vertical scale of REW for dBV display and so the indicated level is -0.1 dBV.
What is the full-scale input value in dBV ?
(it's interesting to know the THD "spot-point" of ADC in dBFS).
Regards.
Frex
Congratulations, you have done a very good job !
The PCB design looks great.
I'm very happy to see that my previous work has inspired others DIYers.
And you seem to have more finished your work than me !
I still hope to be able (a day) to continue my previous work on the OSVA,
even if my personal life don't permit it for now or only for short time to time...
I will look in depth your remarks about your designs issues, and will follow
of course your own progress on this project.
One question about your THD measurement, you seem to have calibrated
vertical scale of REW for dBV display and so the indicated level is -0.1 dBV.
What is the full-scale input value in dBV ?
(it's interesting to know the THD "spot-point" of ADC in dBFS).
Regards.
Frex
Thank you Frex, your work is quite remarkable.
My project was started in May 2020 and has been progressing slowly for three years.
Majority of work was done starting May this year and it's still in progress.
As for your question, I don't quite remember how I've got those figures (-0.1 dBV AND -0.1dBFs), so today I've decided to repeat measurements.
To my big surprise, at full voltage swing on ADC inputs (around 3.530Vrms according to my 34465A meter) REW level was -21dBFs, after that level system goes to clipping. The same happens with playback - at 0.0dBFs REW generator setting, the output level is much lower than expected 20Vp-p.
Interestingly, if I boot linux and run Audacity recorder, it's showing 0.0dB at 4.99750V DC level on input, which is quite correct.
Not sure now where the problem is - Win11 ASIO driver or what? Did you ever have this problem?
My project was started in May 2020 and has been progressing slowly for three years.
Majority of work was done starting May this year and it's still in progress.
As for your question, I don't quite remember how I've got those figures (-0.1 dBV AND -0.1dBFs), so today I've decided to repeat measurements.
To my big surprise, at full voltage swing on ADC inputs (around 3.530Vrms according to my 34465A meter) REW level was -21dBFs, after that level system goes to clipping. The same happens with playback - at 0.0dBFs REW generator setting, the output level is much lower than expected 20Vp-p.
Interestingly, if I boot linux and run Audacity recorder, it's showing 0.0dB at 4.99750V DC level on input, which is quite correct.
Not sure now where the problem is - Win11 ASIO driver or what? Did you ever have this problem?
Attachments
Hello Dortonyan,
Sorry for the late answer.
I have tested both on the input stage of the OSVA.
Practical results are better with the ADA4945, at least at the frequencies l made tests.
That may also depend to how the amplifier is powered , many configurations
are possible.
Regards.
Frex
Sorry for the late answer.
I have tested both on the input stage of the OSVA.
Practical results are better with the ADA4945, at least at the frequencies l made tests.
That may also depend to how the amplifier is powered , many configurations
are possible.
Regards.
Frex