Mains Effects on Audio Systems

Does your power supply connection affect audio quality?

  1. RobHolt
    Last summer (July 11) I did a little test in response to some threads discussing the effects of different mains plugs, sockets, cables and cable supports.

    In essence what you have below are two music files taken from the output of my pre amp, but with the system and ADC fed mains supply in the following two ways:

    - Direct connection of each component to the Olsen distribution block which runs on a dedicated spur back to the mains distribution unit. That's the normal way in which the system is connected. In this instance 'system' means a CD player on which the music track is played, pre, power and ADC.

    - Plug socket at the far end of the house some 15 meters away from the mains inlet to which I connected in series - 1 trouser press via it's own 2m flex, one uncoiled 10m garden extension lead connected via the iron socket on the press, another 5m garden extension lead, another 3m B&Q extension block with four plug sockets to which the system components above were connected. Midway along this I connected a 500w hairdryer which was running throughout the test recording, and at the second extension point was connected an 850w power drill, powered-up three times for several seconds during the recording.

    While the recording was taken from the pre amp output in order to keep everything in circuit, the power amp was driven via attenuator from the tape output - important as the power amp presents a varying load on the mains while playing.

    These pictures show the order of connection:







    So in summary:

    - 3 mains extension leads all in series
    - 35 meters of cable
    - 5 series connections
    - 1 power drill
    - 1 Hairdryer

    .....Nice bit if George you go!

    As a follow up, perhaps now might be a good time to consider the purpose of such testing.

    For me, the intention is to simply make listeners ask questions when presented with possible solutions to system problems, or suggestions for possible improvements and upgrades.

    As with the other tests around microphony, interconnects and Simon's multi-pass adc/dac these examples are intended to contribute to continual discussions on these subjects and to contribute another experience into the great melting pot of what matters in high-end audio.

    They are in no way intended to say that mains effects, cable effects, microphony or compound distortion effects do not exist. That would be absurd and there are very real, properly observed examples for all of these things. The real question concerns the point at which these and other effects become audible and this is the area in which I believe many audiophiles have confused priorities.

    Partly, I believe this is because many don't perform even the most cursory investigation into hi-fi audio in it's purest form, which is electronics. Wasn't always the case and if we could jump into our pfm time machine and go back a few decades we'd find a better grasp on some basic but important understanding of what does and doesn't influence audio systems. I'd more than half an inkling as to what this test would show because I'd done some research into mains. No more than anyone else can do as there is plenty of information out there, readily accessible.

    But not everyone wants to investigate and many are happy to just listen.

    That's fine and ultimately the only way, and I would never argue that instruments and bench tests can or should eliminate listening tests. Some do; I don't except for some special cases confined solely to circuit performance.
    For this group I would simply urge that they familiarise themselves with the potential unreliability of sighted testing when comparing different components. The problem is of most concern during comparisons, less so where you simply sit in front of a system and make a judgement in isolation. The latter raises fewer issues - basically you like it or you don't!

    Bringing this back to the purpose of these tests, use them as a prompt to investigate and ask some challenging questions.

    So when someone suggests that swapping the power cord on your CD player at considerable expense will make it perform better, challenge the claim.

    Ask what this cable is doing that your stock one isn't, ask about the testing process that is supporting the manufacturer's claims. Insist on an unsighted listen and perhaps think about the time you read the story about the trouser press, power drill and hairdryer, just for some perspective :)