Digital Radio Update: A Redesign That Sips, Not Sucks Power

Readers may (or maybe not) recall the blog post “Digital Radio Sucks Power While it Sleeps,” in which Mike Meaking chronicled an energy audit he carried on his home appliances, originally, which alerted him to the power consumption of a then-one-year-old digital radio (shown below). Even when it was supposedly ‘off’ or ’sleeping’ it was apparently consuming five and a bit Watts, for just being plugged into the mains…

In that original blog post, Jason Voice of (the manufacturer of the radio) commented in a very detailed and measured way, explaining the advances made by digital radio and some confusion over quoted figures for the older, non-EcoPlus, versions of the radio in question.

“While some of the points raised in Mike’s article are valid, the piece is generally misleading with regards to PURE’s DAB radios and does not provide a fair assessment of the actual situation. It’s important to point out that the DAB equipment being referenced isn’t entirely reflective of where DAB technology is today, and particularly where we (PURE), the designer and manufacturer of the product used in Mike’s article, are at too.

In 2006 PURE undertook a drive to reduce the environmental footprint of all our radio products in the form of a reduction in power consumption (while playing and while in standby), using materials from recycled and sustainable sources, optimizing packaging size, and using components that minimized environmental impact. It set an entirely new standard of design and development within PURE which was named ‘EcoPlus’ and it was our intention that all future products would (and do) adhere to these new standards. On top of this EcoPlus development was extended to included the redesign and manufacture of some existing PURE products too - like the Élan DX40 used in Mike’s article - and it’s here where we need to draw attention to a couple of points raised.

The description and readings of the PSU in Mike’s article are being taken from the older - pre EcoPlus product but are being cross-referenced and compared to published figures for the newer EcoPlus radios found on our website. One of the many EcoPlus modifications to the Élan DX40 forced a change to the PSU type and it now ships as standard with a 12v switch mode power supply rather than the older 9V linear, non EcoPlus version used in Mike’s article - and the difference is considerable (and not because we ‘forgot’ about power supply losses in our quoted figures). The off-load power consumption of the EcoPlus switch mode PSU is 0.3W rather than the 2.9W stated in the article, and to make easier reading I’ve broken down the specifications of the two types of PSU under discussion…Using the linear PSU (9v, 1.5A), non EcoPlus radio used in Mike’s article:

PSU OFFLOAD: 2.7W
Standby: 4.95W
Operation: 4.95W (zero volume, for consistency across PSU measurements)

Using the switch mode PSU (12V 0.8A) supply, new EcoPlus radios.
PSU OFFLOAD: 295mW
Standby (energy saving OFF): 2.05W
Standby (energy saving ON): 1.15W
Operation: 2.2W

Mike’s findings are mostly correct for the older non-EcoPlus versions of the radio but at the same time highlights exactly why PURE embarked on the new EcoPlus standard of design, and EcoPlus development hasn’t stopped either. PURE now test to EN62087:2003 (the measurement for the power consumption of audio, video and related equipment) and many of our products now meet the strict Energy Saving Trust (EST) requirements of sub 1W standby, sub 3.5W operational (with 50mW of audio). If you consider the power requirements of modern EcoPlus DAB products like the PURE Siesta (0.7W standby\ 2.5W operational) and the PURE Evoke-1S (0.7W standby\ 3.3W operational) then you start to see a clear picture of just how far DAB technology has come - and in what is a relatively short period of time.”

To bring things fully up to date now, Jason  generously sent Mike an Evoke-1S to evaluate, complete with its EcoPlus energy saving technology.

Here is Mike’s evaluation:

“I immediately noticed that the ‘linear’iron/copper transformer power supply that my older radio used had been replaced with a custom made ’switcher’ supply rated at 6.0 Volts, 2.0 Amps that was more conveniently smaller and lighter than the old one. Repeating my previous DC input power measurements I noted that the radio consumed just 70mA (420mW) in standby and about 300mA (1.8 Watts) at low sound volume.

Measuring the AC power consumption with my (same) ‘cheapo’ Maplin power meter I noted a standby power consumption of 1.5 Watts and a low volume consumption of 2.3 Watts. These figures were better than with their published specifications. As a further saving it is possible to configure the radio for ‘energy saving’ and when set, I measured just 0.8 Watts
standby power consumption. I then checked the AC supply current a using a conventional AC meter and measured just 3.5mA which confirmed my ‘power’ measurements.

These figures demonstrate the reduced operating power consumption of the circuitry and the greatly improved efficiency of the switcher power supply which were impressive and more than lived up to the manufacturers claims.

As with my old radio the reception and audio sound quality were excellent.

This episode shows that some manufacturers are taking energy saving seriously and that with a bit of development effort products can be greatly improved. Whether this will ’save the planet’ is perhaps, debatable ?”

Indeed, credit where credit is due to Pure - both for tackling the issue itself, and responding to the original blog post and generously offering Mike a new product to evaluate.

Thanks to our sister publication EW, for tracking the follow-up on our original blog post.