July 31, 2016
 by Paul McGowan

If it plugs into the wall it has a power transformer.

Power transformers have an impact on sound quality—one that is not small nor trivial. In fact, power transformers play a significant role in our sound systems, yet not that many designers pay them close enough attention.

I figured we’d delve into the nature of these beasts over the next few days. A lark, really, but perhaps one that will help a few gain understanding of what’s inside their equipment and why it’s there. Let’s start with that.

Power transformers have two key functions: isolation and proper voltage. Let’s talk isolation first.

We know better than to stick our curious fingers into the AC wall socket. While not usually lethal in the United States, that isn’t true in most of the rest of the world where voltages are doubled. You definitely don’t want 230 volts coursing through your heart for too long. Isolating the equipment you interface with is a good thing, and transformers do it well.

Near magical devices, transformers work through invisible means. There is no physical connection between the wall socket and your equipment. Instead, power is transferred through a magnetic field, helping keep us disconnected from the house wires—and safe.

Tomorrow let’s look at the second function transformers provide.

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17 comments on “Transformers”

  1. Having a big power supply is one of the bedrocks of great sound.

    I am having my tube pre amp modified. I was quite pleased when I was sent pictures showing the progress, and noticed in the stock transformers place a nice big Lundahl Transformer and equally sizeable Choke!

    I think return shipping will cost a bit more then what I paid shipping it out considering the Iron in her now 🙂

    Looking forward to part II!

  2. Paul,

    I don’t understand your comment about the isolation of the house current leaving you safe from it. Though what comes out of the other side of the transformer may not technically be the house current, it is far from safe. I once received a nasty, almost disabling shock when I accidentally contacted a 190 volt section of the power supply. In fact, my TV warns against dangerously high voltages inside. Please explain further.

    1. I should have suggested “safer” instead. Clearly a big enough transformer can deliver quite a wallop. But isolation is still preferred to a direct connection between you and the wall socket.

  3. If the quality – and not the pure power capacity – of the mains is that crucial for the sound quality to be generated in a most reproducible way I cannot understand why manufacturers of Highend devices do not primarily take care for a Highend power supply module. A manufacturer of a ventilator for respiratory care has to observe most carefully the quality of the different standards for pressure supplies in each country thus being able to warrant a precise metering of the flows administered to the patient’s lungs. There is a most obvious difference between “Yes, the ventilator runs!” and “Fine, the ventilator delivers what the volume I set!”.

    1. At one time resperaters depended completely on the power lines. With only a generator that the hooenwas to start in 30 seconds or so.
      Many people suffered for this poor concept. Newer ones now have a built in ups inside them.
      The condition of the power seemed to me to not matter as long as the psu inside was good enough to keep the circuit board happy. What we need is something far more stable in order of magnitude I think .

  4. Paul – our world is getting smaller and people are more mobile. Today more than ever a growing group of music lovers have to contend with 110 and 220v domestic sources and thus occasionally must resort to a step-up or step-down transformer. And many global companies provide universal power supplies (100-240v).

    What are the sonic implications of using a transformer? As a purist, i can guess at your bias. If you say “bad’ then why? Has anyone heard a difference? Is sonic impact greater for high wattage devises or low? If your 110v preamp has an excellent internal power management system, does it matter that power is coming to it from a device stepping down the voltage from 220v?

    Hope you might address some of these ideas…


    1. In my music room I did something most do not.
      Yes it’s all separate circuited and I do use Paul’s power plants. But I take the two phases at a voltage of 208 in and then use a step down transformer to make 125 volts. I use one phase for one power plant A and the other for power plant B. I also use a separate ground for the audio meaning he audio is complelty separated from my home in all ways.
      Is it better I think so

  5. Since the issue is power transformers , Has anyone used the Db -5, manufactured by VPI better known as ” magical bricks ” and if so , what were the results?

      1. I thought I was the only one who used and continues to use this kind of “Snake Oil” for some.

        The Db -5 really make a difference particularly in tube equipment . Maybe someone remembers Enid Lumley , she recommended putting a magical brick above and below each transformer in the Premier One, it is what I do , how right she was .

        I think that perhaps are not as necessary in devices whose transformers are of toroidal type . I do not know.

        But one of the latest photos from HP at home. testing equipment, he showed magic bricks on ultra expensive amplifiers

  6. I think what you are addressing with “bricks” and assorted products is stray EMI/RF. As we continue to rush towards an interconnected world with wifi and cell phones etc.

    Some equipment will be very sensitive for lack of or poorly designed shielding.

    Most older homes are not grounded properly. That’s a big problem.

    Well designed SE cable helps. Never using cheater plugs to defeat the ground leg. If possible, run power amps on a separate circuit.

    Keeping power cords as far away from other cables. More extreme would be additional shielding around transformers, active/passive EMI/RF. Like those Audio Magic pulse devices, Bybee has a couple different solutions also.

    Lowering the noise floor through smart placement, and following standard electrical codes can deliver more bang for the buck then buying kilowatt priced cabling.

    Junk in, junk out.. You have dirty power going in.. You’ll be amplifying it going out and that will and is the primary cause of underperforming systems.

  7. I always wonder how to do that if I read : keep power cords (far) away from other cables.
    How do you do that, since power cords and interconnects/speaker cables come out of the same device (e.g. amp/player).
    I don’t glue them together, but keeping them away from each other…? Beats me. 🙁

    1. Typically you can try to “bundle” the ACs down one side of the rack/stack, which may involve some being run at a right angle across their shelf to get them all on the same side. Pick the side the majority of AC inlets are on in that particular stack of gear. Try to keep ICs away from ACs as much as possible, and when they must cross, try to cross them at 90 degrees.

  8. I understand what you mean. What I did was bundle the interconnects together and tried to route them in the most direct path to the components.

    What I plan to do with power cords is use the power base from PS and run custom sized “shorty” power cords into the base(s) then route, bundle those away from everything else.

    There is EMI/RFI shielding wraps and looms that are available if you have a troublesome set up.

    I live out in a rural area and I have my outlets configured to supply my amplification on a dedicated circuit.

    Hope that helps!

  9. I’m a little hesitant to post this, I’m not an expert by any means, but I’m going for it … Paul said sticking your finger in a 230 volt socket is far worse than in a 110 volt socket, actually my understanding for some time has been it’s not the voltage that is lethal, it’s the current. A quick internet search indicates that old adage to not be entirely true, it’s a mix of voltage and current that kills. As a point of reference a few milliamperes across the heart can be deadly, but conversely being zapped by thousands of volts (think spark plug wires) can give you a jolt but are essentially harmless. Not sure if this really means much to the conversation but I felt the need to say something.

    One thing I would like Paul to discuss is transformer mechanical hum. I’ve had issues with it and so have others and it would be helpful to get a better understanding of what causes it and what can be done to prevent it.

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