How to bridge an LM3886 with an input transformer - diyAudio
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Old 9th April 2011, 06:14 AM   #1
MtBiker is offline MtBiker  United States
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Question How to bridge an LM3886 with an input transformer

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.
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Old 9th April 2011, 06:21 AM   #2
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Without CT connected to ground ,which is the right way ,at least on the secondaries that 'serve' the two ICs ,the voltage swings....how ??
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Old 9th April 2011, 10:01 PM   #3
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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?
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Old 10th April 2011, 08:52 AM   #4
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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.
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Old 14th April 2011, 11:41 PM   #5
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You'd be better to make full use of those nice transformers and use fully balanced inputs to the LM3886 amps.
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Old 15th April 2011, 12:25 AM   #6
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Your schematic shows a shorted primary winding ????.
Else wise the circuit should work fine.

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Old 15th April 2011, 01:16 AM   #7
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Quote:
Originally Posted by mrfeedback View Post
Your schematic shows a shorted primary winding ????.
Where?

se
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