Wrapping it up

December 4, 2016
 by Paul McGowan

We’ll wrap up our series on balanced audio today. I think it’s run its course and then some!

The last balanced piece I want to touch upon is the phono cartridge. Phono cartridges are all balanced. This is because a phono cartridge is a coil of wire with two ends—naturally balanced audio comes out. Unfortunately it’s mostly connected as if it were a single ended device. What a great tragedy!

I have never really figured out why phono cartridges and their amplification devices are mostly single ended inputs. We are as guilty as the next manufacturer. Until recently, just about every phono stage we designed connected one side of the balanced output to ground. Our latest, the NPC is a balanced input. But that’s rare.

So, what have we learned during this series?

  • There are three main areas of balanced amplifiers and not all are incorporated in products. In fact, most products don’t employ all three.
    • Balanced input
    • Balanced amplifier
    • Balanced output
  • Balanced inputs are common, usually connected to single ended amplifier topologies
  • Balanced outputs are common, usually tacked on to single ended designs
  • The big advantage of a balanced input is common mode rejection, where noise signals are squashed
  • The big advantage of a fully balanced amplifier topology are many, including lower noise and distortion

Tomorrow we’ll move on to an interesting new product for vinyl records.

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16 comments on “Wrapping it up”

  1. Until today the phono cartridge is the only truly balanced source, due to its intrinsic nature.

    It is a mystery why the audio industry in general (except for a couple of manufacturers) imposed on the market the manufacture of single ended phono preamps. This includes manufacturers of arms and turntables.

    The weird thing is that in the late 1970s, James Bongiorno manufactured the Sumo line of amplifiers, which at that time were practically the only truly balanced amplifiers, but he did not manufacture balanced preamps for phono cartridges, instead the Sumo amplifiers Have elaborate circuits to convert the unbalanced to balanced signal. (That is, the opposite of what has been done and is still being done) in order that it enters the main amplifier, but in turn, the amplifier can be fed directly with balanced signals by an automatic by-pass of said Circuits.

    I ask: Is it so difficult to design and build a true balanced phono pre-amps? Why almost the majority of the industry did not do it?

    Mysteries of the audio industry.

  2. Balanced connection is mainly to reject noise picked up by the cables. If the cable is short like that of the phono cartridge, I don’t suppose it is worthwhile to spend extra money to get rid of the minimal noise from that end. Anyway not most of the listening rooms are so noise free in themselves and amplifiers, pre-amps have their own noise which cannot be eliminated by balanced connections.

  3. I do use a balanced connection into a balanced phono preamp. I agree that it’s kind of a tragedy for most phono stages to throw away the benefits of the balanced signal from the phono cartridge — particularly a low-output moving coil. Why allow the noise picked up by the tonearm wires and interconnects to get boosted by 60 dB in the phone stage? Crazy.

    1. The tininess and fragility of the signal of a moving coil cartridge must be protected during its long way to reach the voice coil of a speaker, and the most rational form is through truly balanced lines.

    1. Yup, NPC phono input is balanced. What’s perhaps confusing is that there’s only a single ended RCA connector. We simply do not tie the outer shell of the connector to ground. Rather, it goes into a balanced input. It isn’t necessary to have an XLR connector for balanced.

      1. Sweet as…now if one could just disable the RIAA filters that would the bomb…

        I think I need to move the NPC much closer to the TT arm for reduced risk interference. I recall the shielding around the transformer was pretty generous too. And my DS Jr sits right below. so within easy reach of the I2C HDMI connection. or balanced outputs to my pre / processor

  4. In the past I had two balanced (input) phono amps (Gryphon Orestes and Omtec Antares) which I used in balanced mode and also compared with single ended.
    Balanced was little better, but don’t expect differences like i.e. between DS firmwares, different cabling or anything like that unless there are further differences inside the phonostages due to the different inputs, that also change sound.

    For me it’s like with many other singular design aspects (transformers in separate chassis, audiophile semiconductors, dual mono design etc.). Very few if any manufacturers use them all with no compromise. All these little aspects play a role but at the end the whole concept and implementation, finally overall sound make the decision.

    Nevertheless it’s strange that some obvious and inexpensive design features like balanced design at not used generally.

  5. Paul’s conviction and persuasive writing moved me to invest in some balanced replacements to connect my DirectStream to my custom Blue Circle pre-amp. The soundstage is larger; there is more detail; dynamics are enhanced substantially. Thank you, Paul, for the courage of your convictions and for the force of your writing. I do wonder why balanced audio hasn’t simply “taken over.” Audiophiles are universally keen to spend a little more to enhance SQ. And you’d think the association with pro audio would be irresistable. If there is one weakness in Paul’s treatment it is his neglect to articulate the best argument of the single-ended school (which apparently includes most of the UK). Consider, by analogy, the almost universal preference by audiophiles for MC cartridges over MM cartridges. Why doesn’t balanced audio dominate in the same way over single-ended? There must be an explanation, if not a good explanation. For my part, I will say that I think I hear a more convincing timbre from single-ended interconnects when it comes to human voices, especially in the higher registers. Overall, the balanced presentation is decisively better.

    1. Great! I think it’s partly due to the fact that a number of manufacturers refuse to embrace it, though for the life of me I cannot imagine why. It’s neither expensive nor difficult to implement. We can agree that no consumer grade gear has it – I could only imagine the bewildered look on a consumer’s face seeing the “professional” connector on their equipment. And, we can agree that most “pro” equipment used to have it, but increasingly they are moving away from it.

      Personally I would be suspicious of motivations from a high-end audio manufacturer refusing to put balanced connectors and functionality of a piece of kit. Sure, it’s understood when that kit (even from a high end manufacturer) is targeted towards consumers, but if pointed at the Audiophile market and people who care about sound quality, it escapes me.

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