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F.A.Q. and R.A.Q.
Sample Champion


F
requently Asked Questions
and... Rarely Asked Questions

 

 


Answers

[1] Which is the accuracy of a measurement done using Sample Champion ?

The 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.
If 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.

 

[2] Which sound cards are more suitable for Sample Champion?

Any sound card working under windows 95/98/2000/NT4 in full-duplex mode is suitable. Nowadays all sound cards satisfy these requirements.

Some sound cards have peculiar characteristics.
For example:

  • Turtle 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.
  • Last 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 Champion.
  • Good 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!

 

[3] Why Sample Champion requires a lot of RAM memory?

This 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.

 

[4] Is Sample Champion Y2K compliant?

Yes. We have found no negative Y2K results in our tests.

 

[5] How can I test whether Sample Champion works perfectly with my PC configuration?

There is a test that can be done.
First of all download the full-working trial version and install it.
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 audio streams.

The test:

  • Connect in loop back the input and output of your sound card
  • Start Sample Champion and open the Impulse Response and Info windows
  • Set a sampling frequency of 44100 Hz and the 'Repeat' mode
  • Start a Sync Rec&Play loop of 4096 cycles and read the peak position of each cycle, in the info window
  • Adjust, 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 times.

If 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).

Note 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.

Note 2: See the FAQ about sound cards. If you have a SBLive or similar, perform the test at 48 kHz.

Note 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!

ANYWAY, the above test is very significant and, if performed correctly with positive results, can assure you that Sample Champion works fine.

If the problem is caused by the sound card, see the above FAQs about most suitable sound cards.

 

[6] If I have more than one soundcard in my system which is actually used by Sample Champion?

Sample 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. 1.0.2.198 and above the audio device can be selected (see Settings|Hardware dialog). If you have an earlier version, download the last one.

 

[7] About full-duplex operations, should I play at 8 or 16 bit the MLS signal?

Sample 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.

 

[8] My SoundBlaster audio card refuses to perform full-duplex operations

Download 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.

 

[9] Configuration with HDSP RME soundcards

To make work this excellent soundcard disable the SyncAlign setting!

 

 

This page is also available for download as PDF file

 

New configuration tips:
Most common problems (and solutions)

 

 

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