Dual Monoblock Grounding

[wes-ninja250]

Hey, all!

I just had a sudden thought. When configuring an amplifier as a dual monoblock with shared transformer, will there be a ground loop issue when the source connects both signal grounds together?

Should I be connecting both signal star grounds together in the chassis, then, since they won't truly be separate anyhow?

And if so, should I be connecting both power grounds together? How about both half-grounds (PG+, PG-) at the power supply PCBs?

Design is BrianGT's LM3886 Rev 1. Current wiring is literally for two mono amps, but one big toroid.

Thanks,
Wes

[pinkmouse]

Just star it all up, and you should be fine. That's what I did with my 4780s

[wes-ninja250]

Do you mean, four stars (Power L, Power R, Signal L, Signal R) starred together, or one giant star?

I'm thinking you mean -- connect the PG+/PG- of each power supply board, each input ground, and each output ground together?

Will that affect cross-talk between channels / stereo separation?

(draw, draw, draw)

Is this what you mean? See attached. Seems almost too easy. Also, makes me wonder if PG+/- shouldn't be connected right on the PCB... as well as the grounds at the inputs/outputs being connected together right at the connectors.

Thanks,
Wes

[Mad_K]

Just use one rectifier. Join PG+ and PG- at the rectifier pcb.
Make this your main star grounding point.
Here you connect the chassis ground and PG from each amplifier pcb.

At each amp pcb you connect IG, OG and PG from the rectifier. Do not connect CHG. Keep all grounds separate (except PG+/PG- which by now are just PG) until they meet at the star.