Apologies. Is second to 10 Khz and third harmonics up to 8 kHz. Yes Fuzzmeasure program. Measures has made after having several hours on. And for every picture I made a 5-6 measures 3 logsweep 10 seconds each to check out always see similar.
Last edited:
Dotted is 3:rd, solid 2:nd.
MB2 doesn't hold what it promised. Either the design was not OK or the DAM could not recreated it. Seems like the former.
//
MB2 doesn't hold what it promised. Either the design was not OK or the DAM could not recreated it. Seems like the former.
//
Thanks for the measurements. What "sound card" did you use. Is it via the buffered or unbuffered output?
These are very interesting results. Thank you for taking the to test and collate them.
Balanced?
Balanced should have slightly lower levels of 2nd harmonics than unbalanced.
The test signals are generated using SignalSuite: SignalSuite Details
Under periodic signals tab: 3000Hz, 100% amplitude for signal and output, and I/O calibration set to FS=1.
Thanks
Thank you so much oneoclock! At least some real measurements of frequency and impulse response of this DAC.
Now why NOS has less than perfect impulse response with both pre and post ringing present?
spzzzzkt: please no tire (tyre in your world) taunt this time.
Thank you so much oneoclock! At least some real measurements of frequency and impulse response of this DAC.
Now why NOS has less than perfect impulse response with both pre and post ringing present?
spzzzzkt: please no tire (tyre in your world) taunt this time.
NOS have analog filter output, a C on the output. That's why we have impulse with a few pre and pos ringing.Now why NOS has less than perfect impulse response with both pre and post ringing present?
I am pretty sure the motu soundcard ADC is ringing, the capacitor on the output of the dam will not have any preringing at all and only very very little post....
On the scope NOS shows no traces of ringing.
Last edited:
A first order rc filter cannot have any pre-ringing, and has no post ringing either.
The full amplitude NOS filter problem could be related with the "problem" of the DAM of handling the maximal alowed negative ampltude.
So you could say there is some extreme clipping for just one value of the amplitud (the max negative one).
This applies to the amplitude after filtering. So the direct correspondence to the PCM aplitude is only given with the bypass or NOS filter.
With 32 bit data high negative amplitudes such as x80 00 00 01 seem to be truncated to 24 or 28 bit and thus lead also to no impuls instead of a maximal negative impulse.
This is probably due to the fact that the natural signal range of a sign magnitude DAC is +2^n-1 to -(2^n-1) and that the allowed range in PCM data is +2^n-1 to -2^n, and some "special case" handeling is missing in the code.
Soren promised a fix of that with the next firmware.
So you could say there is some extreme clipping for just one value of the amplitud (the max negative one).
This applies to the amplitude after filtering. So the direct correspondence to the PCM aplitude is only given with the bypass or NOS filter.
With 32 bit data high negative amplitudes such as x80 00 00 01 seem to be truncated to 24 or 28 bit and thus lead also to no impuls instead of a maximal negative impulse.
This is probably due to the fact that the natural signal range of a sign magnitude DAC is +2^n-1 to -(2^n-1) and that the allowed range in PCM data is +2^n-1 to -2^n, and some "special case" handeling is missing in the code.
Soren promised a fix of that with the next firmware.
Last edited:
😎 That is great work!
So the Signal Suite test signal is varying?
Looks like I need to go back to .wav files.
My comment was thought as possible explanation of the higher distortion of NOS 0dB plot in the second PDF.
I am quite sure, the obvious clipping of the square wave with the added small sinus should be no "fault" of the DAM but just an effect of the filter+gain, i.e. the (digital) signal after being filtered and gain adjusting contains values above the maximum allowed digital signal which then are "clipped" to the maximum (as nothing higher can be handled by the DAC ladder).
You should be able to see that also with sox, applying there the filters and gain, clipping should be reported.