April 2015 editorial

The problem of the serious hifi brands and their inferior power adaptors

[Damaged AC/DC power adaptor]

Author: Richard Varey
Published: May, 2015

Today, many hi-fi products are now powered from external electrical supply adaptors and modifiers, either custom designed or specified by the circuit designers. Equipment is easy to design this way, with any noise radiated from power supply components distanced from the sensitive low voltage audio circuits. I'm talking here mainly about those “wall wart” transformers that step 240/120V mains supply down to a low voltage and current for driving delicate electronics circuits and components. So what's the problem?

Many OEM power supply units - especially those generic units that are mass-produced in low-cost economies - are woefully inadequate, some being so underrated that they are prone to overheating and failure, sometimes catastrophic in effect. This ranges from physical damage from overheating, such as melting, cracking, breaking, and exposed mains connections, to combustion with noxious fumes, but also including damage to electronics.

Some units operate acceptably safely, but prevent the full performance potential of hi-fi equipment to be achieved. In any powered audio equipment the power supply influences the sound, by determining stability in biasing or driving active components within the desired part of their operating characteristic. Some power units hum or run hot due to use of an underrated or poorly assembled transformer.

I have experienced this problem firsthand in products supplied by hif-fi stalwarts such as Cambridge Audio and iFi. Both are innovators and have built up reputations as serious contenders in the home hifi arena. It's such a shame that they have fallen into the trap of sourcing external accessories that are not up to the job.

[A bunch of AC/DC power adaptors]

One manufacturer has replaced a power adaptor more than once on more than one of their products. The others' unit failed within just a few weeks of first use - the agent supplied me with several replacements “just in case”! In one instance, the plastic housing melted, exposing the live mains voltage connections.

The suppliers who use badly matched or poor quality units are risking both reputational damage and the safety of their customers when unreliable, even dangerous power adaptors are supplied with their kit.

I see two obvious solutions. Firstly, designers - and their accountant colleagues - need to take seriously the risks they are building into the supply of equipment with cheap power transformers. Secondly, users can look to replace the nasty “wall wart” with a properly designed, tested, and certified power unit.
There are plenty on offer to be found if you feel the need to recognise and solve this unnecessary problem for yourself. Wouldn't it make more sense for the brand owners to ensure they sell only top notch product?

Brand reputation damage undermines the value-for-money attitude to brands of discerning customers, and the end user will not tolerate expensive high performance equipment which is vulnerable to becoming unreliable, under-performing, damaged, and unsafe because of a cheap external component that is the lowest cost part of the package.
Reputations and brand loyalty will suffer, as will profits, as manufacturers lose respect for their products and business practices when they try to avoid responsibility as well as liability. Other costs include damages and compensation for personal injury claims and breach of consumer guarantees legislation. Time for some company executives to front up and fix this problem. Users lose out on the promised euphoric musical experience that is promised in the advertising. If you have a horror story or a tale of sound (excuse the pun) business practice, an impressive product, or ingenious solution, I would be interested in hearing from you.

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© Copyright 2015 Richard Varey - richard@tnt-audio.com - www.tnt-audio.com