DS MKII - XLR or RCA cable

Hi @Ted,

Is it true that XLR electronics remove 2nd order harmonics as part of the XLR noise filtering/cancelling process?

And as such, is the RCA connector therefore in the MKII perhaps preferred?

Thanks

The DS is a balanced design so 2nd harmonic Distortion is already suppressed. If your preamp/amp is balanced then XLR is the way to go.

Note: balanced design removes 2nd harmonic Distortion, not the 2nd harmonic. Balanced is good, not bad for fidelity to the signal.

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Common noise rejection is performed on the hot and cold wires of balanced connections. Because hot and cold have a equal signal level referred to ground only in different polarity. Noise caught up in the connections and interconnects has equal polarity superimposed on the different polarity hot and cold lines. The filter only filters equal polarity noise. Since the signal is not equal polarity at any point or frequency the filtering will not harm the signal at all.

This is not possible with RCA signals as the cold signal is typically connected to ground. The common mode rejection filter will not work.because the noise on the cold lead is already drained to ground and the the noise on the hot lead will not be rejected.

Common mode noise cancellation does obviously not work in a system that has at no point a common mode rejection filter i.e. balanced to single ended conversion. Like when everything from source through power amplification and even speaker connection remains balanced. In those systems the at source level picked up common noise gets amplified, filtered and all other treatments the signal gets and will not be so common mode anymore at the end due to imperfections in the balanced design, for example the volume control.

For that reason Mola Mola has the common mode rejection built in their Makua pre amplifier, Kula integrated and Kaluga power amplifier, where the common noise is filtered out (i.e. signal is converted to single end) before all the different stages the signal has to pass through.

Octave Audio, another high end audio brand (tube amplifiers) utilizes the same principle. They offer the superior XLR connections but the internal electronics are single ended.

Balanced connections always come at a financial cost, but equally they are always the preferred connection.

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I disagree about the conclusion that a fully balanced system cannot reject noise. I have the DS DAC, an Electrocompaniet EC4.7 pre-amp and a Musical Fidelity M8-500S power amp, all of which are fully balanced – or more importantly, differential, all the way through the chain.

(See Balanced and Differential )

In my system, neither of the speaker terminals is tied to ground. When the amplified signal goes out to my speakers, it is still differential. The amplifier has four separate mono circuits working as a pair of twins – each is responsible for one phase of the signal on one channel. Their active outputs go to the speakers, the ground side of the circuit does not. Provided none of the unbalanced noise on the inputs drives an individual amp circuit beyond linearity, nothing but the differential signal will drive the actual speakers and (with the exception of the volume control issue you mentioned) all the noise will be cancelled out.

Analogue volume control does present a challenge, like you say. If the two channels aren’t attenuated the same then the noise isn’t attenuated equally and won’t perfectly cancel out. That’s another argument in favour of not using a pre-amp, though I have reluctantly conceded that even in my kinda purist solid-state fully-balanced setup the sound seems better since I put that 3rd component in the system. I should try again without though, now that I have done the XS4400 transformer upgrade.