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Quick Start Guide 6
®
Quick Start Guide
©2012 PS Audio Inc. All rights reserved.
Owner’s Reference
PerfectWave DAC MKII
audio dependent on your source material and the program you're using. Some programs, like iTunes,
will always resample the audio to the highest sample rate allowed by the driver - in the case of the PWD
it is 192kHz. Use a program like Bit Perfect, Amarra or Pure Music to bypass the iTunes restrictions to get
native sample rate performance.
The PWD will memorize the last setting chosen for the input you are on. So, for instance, if you
choose NATIVE while on input I�S2 and 192kHz for RCA, the SRC will automatically switch to
that setting when you change inputs.
The PWD offers a wide assortment of digital filters. Digital filters are necessary and used in
all modern DACS but few are as sophisticated as those in the PWD. The problems with any
filter, whether it is analog or digital, are the effects they have on the passband (usable audio
frequencies).
Filters leave several types of negative artifacts: group delay, phase and ripple errors. Some
filters minimize phase and group delay errors while others minimize ripple errors. Each error is
minimized at the expense of the other; thus, there is no such thing as a perfect filter and, as with
many things in electronics, each is a tradeoff with good and bad points.
The PWD has two basic types of filters with several combinations of the two available. The two
filter types are: Linear Phase and Minimum Phase as well as Recursive Non-Half Band (which
is basically a combination of the first two). Within these two main filter types (Linear phase and
Minimum) there are several variations to choose from on each filter, including Apodising and Soft
Knee Filters.
From a user perspective, we recommend choosing whichever filter sounds the best to you
without being overly concerned about understanding these extraordinarily complicated subjects.
Our favorite on the PS system is Minimum Phase Apodising “MP Apod” on the touch screen.
A brief explanation of each filter type appears below.
Linear Phase and Minimum Phase filters
Linear phase filters have been widely used in DACS for over 20 years because they introduce no
group-delay distortion, minimize post ringing and have a phase response that is the same for all
frequencies but at the cost of pre-ringing. Conversely minimum phase filters have some group-
delay distortion, some minimal phase shift with frequency but little pre-ringing.
Most DAC digital filter designs tend to focus on the frequency response and neglect the time
domain response. However there is now an increasing interest in the effect that time-domain
properties of these filters have on the perceived audio quality, thus the PWD offers a choice
between 5 different filter types described in this section.
Generally speaking, linear phase filters are focused on maximizing the frequency domain while
minimum phase filters are designed to maximize the time-domain performance.
Group delay is a time domain issue where different frequencies arrive slightly out of time with the
other frequencies. A filter with no group delay (such as a linear filter) means that all frequencies
Filter
