FET Audio | Hi-End Audio & Electronics DIY Electronics & Repair

After some time, it is time to disclose the FFT measurement of this wonderful DAC by AP SYS-2522.  To achieve this good measurement results, the following changes are made:

1. L5 is removed for both pcb
2. C51 change to 560uF
3. Add two ground wires 1 and 2 (RED) as shown in connection diagram
4. Use separate 9Vac windings for each pcb from R26-10 r-core transformer
5. OCL mode is used

All input signal are throught SPDIF @ 0.5Vpp FS=44.1k 24bit data.

FDA-1 FB connection diagram

FFT FDA-1 FB measurement results

Update Dec 7th 2010: Add new FFT measurement below for distortion and frequency response at -1dbFS, -10dbFS, -20dbFS, -40dbFS and -60dbFS.  Output load at 600 ohm.

FDA-1 FFT 600 load FR and Dist

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