Balanced Output

nick · 5330

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Offline nick

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on: August 05, 2024, 07:55:46 PM
I've had several hundreds of hours on this amp in single-ended mode. Was listening to music as usual one night then it hit me. This amp has balanced out, I know this, I built it!

Re-terminated my headphones to balanced and off we went. Now, from using the forum search, I've worked out that yes, both outputs are simultaneously active regardless of the balanced switch and that the switch just changes the ground. I also know that balanced uses separate grounds in the cabling for L/R channels instead of a shared ground but that's where my knowledge ends.

I could tell immediately that things sounded different. Can't exactly say what without more listening.

Now the question is, would balanced be the "recommended" way to use the amp if one had the choice? What exactly does changing the ground via the switch do? I've read it optimises the impedance but in what way? These burning questions keep me awake at night(not really, but you get the gist) and I'm interested in the technical aspects of this(not an electrical engineer but will pretend/try to understand).



Offline Paul Birkeland

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Reply #1 on: August 11, 2024, 05:53:46 AM
Now the question is, would balanced be the "recommended" way to use the amp if one had the choice?
Beyond the inconvenience of needing a balanced headphone cable, this is a good way to go.

What exactly does changing the ground via the switch do?
It moves the audio ground reference to the center tap of each output transformer and provides an independent -Ve for each channel, so two things at once.

I've read it optimises the impedance but in what way?
This is not really applicable here.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline nick

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Reply #2 on: August 11, 2024, 09:33:57 PM
Thanks for taking the time to explain. Appreciate it!