Got rid of the hum in the left B&G Neo 8 by swapping the Arcam Alpha 8 power amp for a DIY TA2022 amp in stereo mode.
PS for this amp is 2*22vac 400VA toroidal transformer from toroidy, followed by a capacitor bank of 4*10000uF/63V plus the 2*4700uF on the TA2022 board.
Powering the woofers is the 2xTDA7293/channel amp with a 300VA 2*24Vac toroidal transformer followed by 6x4700uF PS capacitors.
Both amps have softstart circuits, but only the woofer amp has spkr-protection, I have a spkr-protection board on the way for the TA2022 amp as well.
Source is a Rpi 3 via XMOS USB to I²S, then to an ES9023 DAC (for now, my DAC/headamp is currently acting as preamp) and on to my AD797+BUF634 headamp with C-L-C filter on the AD797 supply. From there I’ve split the signal with Y-cables giving me sort of two outputs from the headamp/DAC combo.
One pair of cables goes to the FreeDSP classic that handles LF crossover and dipole compensation, the other goes to the TA2022 amp directly.
Alot of new parts that need to settle, but I am pleasantly surprised by the sound thus far. I know there’s alot more to squeeze out, going digital in on the FreeDSP and hook up nice DAC’s via I²S from the gpio header (bypassing the adau1701’s internal A/D’s and D/A’s).
More to come, I am going to listen to the fruits of my labour 🙂