Tuesday, May 23, 2017
e32 Measurements
FFT Spectrum at 0dBFS
FFT (Fast Fourier Transform) spectrum of 1 kHz, 0 dBFS (2 Vrms) signal. The harmonic distortion of the 2nd harmonic at -127 dB (0.00004%), followed by the 3rd harmonic at -121 dB (0.000089%). The higher harmonics are around -135 dB or lower. Also, note that the power line related noise (60Hz and its harmonics) is below -148 dB (0.000004%).


Intermodulation Distortion (IMD)
IMD 19K+20kHz @ 0 dBFS (2 Vrms). The 2nd order difference product appears at 1 kHz and is about -144dB (0.000006%). The 3rd order IMD products produce symmetrical sidebands around 19K/20kHz and are below-116dB.



THD + N Ratio

THD Ratio

Jitter
FFT spectrum (1024K points averaged 8 times) of 11.025 kHz signal at 44.1kHz sampling rate. This measurement exposes the smallest periodic jitters, which would appear as sidebands symmetrically located around the signal. The FFT spectrum is extremely clean, with all the artifacts around -150 dB. Only one clearly defined jitter-related double sideband is visible, located +/- 1kHz from the signal at -150 dBFS.




Noise Floor with USB Galvanic Isolation


FFT spectrum (1024K points averaged 8 times) showing the noise floor measured on the e32 DAC XLR line outputs. The e32 DAC is connected with a standard USB cable to a PC. The noise floor is extremely clean. There are no visible traces from the computer high-frequency noise usually transmitted via the USB connection. The power line related noise (60Hz and its harmonics) is below -160 dB (0.000001%).

Noise Floor without USB Galvanic Isolation
For comparison, the same measurement is taken without Galvanic ground isolation. The noise level is increased by 30dB. This experiment clearly shows the benefits of using Galvanic isolation.



FFT Spectrum at -140 dBFS
FFT spectrum of 1 kHz, -140 dBFS signal. This measurement illustrates the DAC's ability to reproduce the smallest details in a 32-bit system. The -140 dBFS signal is clearly resolved 25-30dB above the noise floor.



Headphone Amplifier - FFT Spectrum at 1 Vrms
FFT spectrum of the headphone amplifier output, with a 1 kHz, 1 Vrms signal into a 60-ohm load. The harmonic distortion of the 2nd harmonic is around -120 db, and the 3rd harmonic is around -106 dB.



Headphone Amplifier - Intermodulation Distortion (IMD)

Headphone Amplifier - THD + N Ratio
 
Headphone Amplifier - THD Ratio

All measurements are performed with the Audio Precision APx525 system, with the line outputs of the e32 DAC terminated with 100KOhms resistors. FFTs are 1024K points, averaged 8 times.

e32 DAC