How to bridge an LM3886 with an input transformer

[MtBiker]

I have 4 channels of LM3886 and a pair of Lundahl LL1545a to bridge them and need some help clarifying grounding. If I want a 1:1 for balanced (or unbalanced) in and balanced out, I can do something like in this picture. I end up with a center tap on either side that are floating--do I need to ground that on the secondary side? In the picture I only have the shields grounded.

[picowallspeaker]

Without CT connected to ground ,which is the right way ,at least on the secondaries that 'serve' the two ICs ,the voltage swings....how ??

[MtBiker]

Why would it need the CT to be grounded? If I had a single secondary, there would be no CT to ground yet it would work the same, right?

[picowallspeaker]

Nope . My basic electronic skills tells that a voltage is developed where there is a different potential of negative charged elements -the electrons- that flow through the conductive materials . ground is universally chosen to be 0 V.
In this very particular application you need to rotate by 180° the phase of it ,so you'll need to FIX a reference point to which relate the change of phase.

[AudioFreak]

You'd be better to make full use of those nice transformers and use fully balanced inputs to the LM3886 amps.

[mrfeedback]

Your schematic shows a shorted primary winding ????.
Else wise the circuit should work fine.

Eric.

[Steve Eddy]

Originally Posted by mrfeedback

Your schematic shows a shorted primary winding ????.

Where?

se