Bridging the Digital

and Analog Worlds
5Consistent performance
across all sample
rates.
Filters should scale with sampling frequency. Period. If you are
using low sample rates, like 8KHz or 16KHz, non-scaling filters
place extra noise in the audio spectrum. This reduces performance
or requires the designer to switch between external filters. All
AKM DACs and ADCs feature switched-capacitor technology,
allowing the on-chip analog filters to scale with sample rate. This
reduces external circuitry and ensures superior sound.
6Look past 20KHz
response when
evaluating sample rates.
What’s the point of supporting high sample rates if you are only
looking at energy from 20Hz to 20KHz. Instruments like cymbals
and horns have harmonic content well past 20KHz. When you test
audio parts at high sample rates, get rid of AES17 and A-weighted
filters and see what is now happening “in-band”. The lack of noise
in this extended audio band will provide a complete picture of
AKM’s audio excellence!
8Does your ADC
go to 11?
Well, ours do (sort of). You see, when you saturate the inputs on
any of our A/D converters, the digital output is “pegged” at
maximum value, no mater how much you exceed the input
maximums. Some parts “wrap around” to negative full-scale
(ouch!) and begin re-incrementing. This forces a system designer
to have to compensate for this wrap around either with an
expensive input circuit or through DSP/CPU programming. AKM’s
approach is simple, valid and predicable in its behavior.)
9Silence is golden,
get rid of the noise.
Spurious noises. Sparkle codes. Spikes. Non-linearity. Periodic
aberattions. Call it what you will. Whether a converter is
converting or not, unwanted tones are unacceptable. With AKM,
the only time you’ll see (or hear) these objectionable signals is,
well, never. Instead you’ll see a truly random noise floor without
specific tones or spikes. This is the result of superior technology
and careful design. With AKM, you’ll crank up the signal and cut
out the noise.
A 16K sine wave was sent to the device under test using an Audio Precision System 2
Cascade. The digital output of the board was connected to an AES digital input on a
PC sound card. For five minutes, the AES digital input was recorded using CoolEdit
Pro. After the data was collected, a digital FFT filter or digital notch filter at 16kHz
was applied. The resultant spikes in the graph show non-linearity or sparkle codes
caused by the errant data.
7Watch Your Power
10
Use AKM for all of
Supply.
your audio designs.
Noise is a performance killer. Make sure that your power supply is
clean and strong. This will improve audio performance throughout
your system. If possible, use high-quality dedicated regulators Sample-rate converters. Class D amplifiers. Performance. Value.
D/A converters. A/D converters. S/PDIF. Codecs. AES-EBU.
with low ESR (converters need fast access to current) and high When it comes to audio, make AKM your first stop. No one offers
PSRR (Power Supply Rejection Ratio). Your ears will be happier if the breadth of products, the integration, or the support that AKM
you do, and your product’s performance will be at its best.
offers.
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