Create an impulse train, 100Hz @ -3dB and save it to a FLAC file:
Python:import numpy as np import soundfile as sf data = np.zeros(44100) data[::441] = np.sqrt(2)/2 track = np.tile(data, 500) stereo = np.column_stack((track, track)) sf.write('100hz_3dB_impulse.flac', stereo, 44100, subtype='PCM_16')
Play the generated file through the NX4 in DAC-only mode and look at one of the output channels on an oscilloscope.
Looks linear-phase to me...
View attachment 22193
Very cool. Thanks for the work! I suspected LP because my Sony MDR-1A headphones sound bloated with mimimum phase filters on my ESS-based Oppo 205’s headphone amp (but sound great on LP filters); and, they do NOT sound bloated on the NX4 DSD. In fact, I’m loving the sound on all my Sony headphones with the NX4 DSD.
Thanks again for the impulse capture on your oscilloscope.