Odds are you already have a fully Balanced Turn Table feed!

Over the last few month I have completed a new phono preamp with balanced inputs. It will replace the current Black Swan as an upgrade. Audio friends have looked at me like my head screwed on wrong. They say to me

“Who has a balanced TT feed?”

Well as far as I can figure – most everyone.

You already know that your cartridge has balanced outputs. There are two independent coils (L and R) in the cartridge and four outputs (L+, L-, R+, and R-) for both MXC ands MM cartridges. Your cartridge suspension system (the Arm) has 4 wires in it. Somewhere in the TT system these wires get moved into heavier more usable leads, typically a pair of coax cables terminated in RCA connectors. Your phono preamp has a pair of unbalanced inputs because the cases to the RCAs are grounded to the chassis at the input.

Where did you move from the balanced phono cartridge output to the unbalanced phono input?

The common myth is that happened when the signal leads left the TT system. You believe that the R- and L- feeds from the cartage were shorted to together in the TT or the arm. This created a common feed of a mix of R- and L- signs. They become what I call ‘entangled’, they are commingled at this point in what we call that a ‘Ground signal, not to be confused with a shield conductor.

Most likely that is wrong.

The reality is that all four signals, L+, L-, R+, and R- are delivered all the way to the preamp input and the independent signals are commingled at the input of the preamp. Sonically this results in the destruction of much vital subtle spatial audio data.

How can you test this premise?

Simple! Unplug your phono inputs, put an ohm meter on the two outside connections on the two RCAs from the TT, and look at the resistance.

I will bet you get infinite resistance making it clear that the two signals, L- and R- are NOT CONNECTED together until they hit the preamp. The clear implication here is that by definition, the are BALANCED signals until they get to your preamp.

Ponder that, I will explain more later if you are interested.

Barry Thornton – austinaudioworks.com

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