Which is the accuracy of a measurement done using Sample Champion
accuracy of a measurement (not considering external devices
like microphones, amplifiers...) depends basically on the sound
card. You can evaluate the performance of your sound card using
Sample Champion itself in a loop back configuration. See application
notes and FAQ #5.
your sound card has poor frequency response, some improvements
could be obtained using MLS filtering and equalization capabilities
of Sample Champion.
A nice solution could consist in using an audio card with S/PDIF
digital IN/OUT and an external high quality A/D-D/A converter.
Which sound cards
are more suitable for Sample Champion?
sound card working under windows 95/98/2000/NT4 in full-duplex
mode is suitable. Nowadays all sound cards satisfy these requirements.
sound cards have peculiar characteristics.
Beach audio cards (Pinnacle, Fiji...) have an excellent frequency
response, low noise and in our test NEVER lost a bit
of sound data or the sync between input and output audio strams.
They work very well also on slow computers because of their
hardware architecture and powerful software drivers. These
audio cards are recommended for Sample Champion.
generation SoundBlaster cards (ex. SBLive, PCI128...) have
a very good frequency response but can be used with Sample
Champion ONLY at the sampling frequency of 12 kHz,
24 kHz and 48 kHz because they work internally always at 48
kHz. Other sampling frequencies are obtained by an internal
frequency conversion that can give poor results with Sample
old first generation SoundBlasters (SB16, SB32, some AWE...)
used on slow computers can experience sync losses caused by
software interference with the video cards. Sample Champion,
in Blinded Mode, operates a workaround. Anyway we reccomend
to update your sound card!
Sample Champion requires a lot of RAM memory?
is a consequence of the very high accuracy used for all internal
operations. For example the FFT (limited for the user to 64K,
but extended for some internal operations to 256K) is computed
on double-precision complex data and using both frequency bands
(positive and negative frequencies) to perform some specific
signal processing operations and in prevision of any future
DSP expansion (using special purpose plugins).
To prevent any resizing or reallocating of the virtual memory
during measurements, Sample Champion allocates, once started,
all RAM memory required for working.
Sample Champion Y2K compliant?
We have found no negative Y2K results in our tests.
can I test whether Sample Champion works perfectly with my PC
is a test that can be done.
First of all download the full-working trial version and
The main thing to test is whether your computer is fast enough
to perform the real-time operations required by Sample Champion
and nothing in the system interferes with the input and output
in loop back the input and output of your sound card
Sample Champion and open the Impulse Response and Info windows
a sampling frequency of 44100 Hz and the 'Repeat' mode
a Sync Rec&Play loop of 4096 cycles and read the peak
position of each cycle, in the info window
if necessary, the in and out levels from the mixer to obtaind
a distorsion-free impulse response; increase
the 'Step' value (if required, see manual for details) until
you can read in the control bar the yellow label 'BUFFER OK'
for at least 1 second. Repeat the above procedure several
the peak is at the same position at every cycle, your
computer can perform real measurements with Sample Champion
to (once calibrated, the peak will be near t=0).
1: When a measurement cycle starts, it is normal observing
a small change of the peak position, that could be advanced
or delayed by one or two samples with respect to other measurement
cycles. The peak must, however, remain at the same position
during a measurement cycle.
2: See the FAQ about sound cards. If you have a SBLive or
similar, perform the test at 48 kHz.
3: If the peak changes its position, during the test, this
means that something interferes with either input or output
audio streams. This is not due to Sample Champion but to the
specific software/hardware configuration.
WARNING: If you experience this, all programs
manipulating audio data in real-time (for example multitrack
recording or other measurement software) on that system could
experience the same problems. However only performing synchronous
playing and recording (and expecially using correlation techniques
with MLS) it is possible to discover them! Sample Champion tells
you the truth!
the above test is very significant and, if performed correctly
with positive results, can assure you that Sample Champion works
the problem is caused by the sound card, see the above FAQs
about most suitable sound cards.
If I have more than one soundcard in my system which is actually
used by Sample Champion?
Champion uses always the first (ore the only) audio device mapped
in the system. If you have more soundcards, the one to be used
must appear as first (number 0). In future versions of SC it
will be possible to select the card to be used.
NOTE: In Sample Champion
Vr. 220.127.116.11 and above the audio
device can be selected (see Settings|Hardware dialog). If you
have an earlier version, download the last one.
About full-duplex operations, should I play at 8 or 16 bit the
Champion can play either at 8 or 16 bit resolution (for backward
compatibility with some old audio devices). When playing tonal
signals it is recommended to use 16 bit resolution, but when
playing MLS signals (just a series of +K and -K, where K is
the output value) it doesn't matter. In our tests we didn't
find any difference using 8 or 16 bits in playing MLS signals.
My SoundBlaster audio card refuses to perform full-duplex operations
and install the latest driver!
Remember also to disable 3D spazialization enhancements and
set bass and treble controls to zero when performing measurements.
If any loss of sync is observed (see FAQ #5) try also other
IRQ and DMA settings because windows can share some of these
channels and some configurations could give poor performances
in terms of audio quality.
Configuration with HDSP RME soundcards
make work this excellent soundcard disable the SyncAlign
page is also available for download as PDF file