This is only a preview of the May 2013 issue of Silicon Chip. You can view 30 of the 104 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "DC-DC Converter For the CLASSiC-D Amplifier":
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SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
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Jim Rowe, B.A., B.Sc
Nicholas Vinen
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2 Silicon Chip
Publisher’s Letter
Do microcontroller projects have
too many features?
One of the advantages of products with microprocessors
is that it is often very easy for the designer to incorporate
additional features with little or no increase in circuit
complexity. And so it has been with SILICON CHIP projects.
Invariably there is a temptation on the part of the designer
to add this or that feature to make it more attractive to the
end user. However, as the hard-nosed Publisher of the
magazine, I often wish that they simply wouldn’t do it.
First, it adds options and choices and that, to me, is “bad”. Every choice and option means that there is the chance that it will confuse the project builder and that
means we get emails from readers seeking clarification.
Second, adding options means more programming time involved in developing
the product. And invariably that means that more bugs have to be found and fixed.
Moreover, more operating features inevitably mean that we have to take up more
space to describe them in the magazine. You can see where I am coming from. In
theory, we subscribe to the KISS principle (Keep it Simple, Stupid); in practice,
we often don’t.
And so it has been with our new DAC project which we have featured over four
issues, this issue being the last. This is a classic microprocessor-controlled project;
lots of features in a relatively simple circuit. It is all in the programming, you see.
In fact, it wasn’t until Nicholas Vinen had finished writing this last article that some
of the more abstruse features were revealed. So when I was reading the article, one
side of me was saying “This is more complicated than it needs to be and Nicholas
has really got the bit in his teeth this time” while the other side was saying “That’s
really clever etc”. I won’t tell which side was dominant . . .
So the DAC project is not just a DAC. For a start, it is a playback device in its own
right and it will decode WAV files, with various sampling rates, stored on an SD card.
It also incorporates a headphone amplifier with its own front-panel volume control.
Both of these were included in the long list of features in the first article. Somewhat
less obvious in that same list of features was digital tone control and headphone
cross-feed. Not mentioned at all, was digital volume control via the infrared remote
control and to top it off, loudness compensation to the ISO specification.
Now digital volume control with the infrared remote I regard as highly desirable, if only for its convenience. I also regard it as the best method from a sound
quality point-of-view, even though some audiophiles regard digital volume control
as undesirable because it involves reducing “bit depth” in the audio data stream.
But loudness compensation is somewhat more debatable. On the one hand, it is a
worthwhile feature because it does compensate for loss of hearing sensitivity at the
frequency extremes when overall playback sound levels are reduced. On the other
hand, if you choose to enable the loudness compensation, it is always going to be
a rough approximation, because you don’t know the level at which the program
was originally recorded and how that equates with the maximum signal level that
can be reproduced in your listening situation. It is a “bit of fudge” in other words,
although undoubtedly far superior to the loudness control often featured in hifi
amplifiers of yesteryear.
At least, the user has the choice of whether or not to use any or all of the digital
control features of our new DAC. Certainly a great deal of design and programming
has gone into this project but I tend to feel that we may have included too many
options which many people will simply never use (and it has taken a lot of time to
program all this stuff . . . Grrr).
What do you think? Should we incorporate lots of features in our microprocessorcontrolled projects or should we keep them simple?
Leo Simpson
siliconchip.com.au
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