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Re: TDA1541A sin(x)/x, I/V ... do I get this right

Hi MBK,
You have a stepped 22.05 kHz outputsignal.
You can not bend the laws of physics: If you want a steep filter to attenuate as much as possible any unwanted highfrequency products above 20kHz you end up with a tenth order Butterworth filter or the like. This filter will have as much ringing and overshoot as a digital filter and bad sound too. The Bessel filter has no ringing or overshoot but less steep response, especially at and near the crossoverpoint. That's why I choose a third order active Bessel filter for my KWAK-DAC with the -3dB point at 10 kHz. This will attenuate about 16 dB at 22 kHz, of course more at higher frequencies.
Please note that a passive Bessel filter ideally has the same amplitude and phase response.

The sin(x)/x is a other issue relating to a slight loss of high's at 20 kHz with NO filtering applied. To me this is of no concern.

It possible to use no filtering at all after the DAC. I believe Kusunoki does it this way. Be prepared for intermodulation products in the high frequencies. Some solid state or tubed equipment; (not mine!); does not seem to like to be bombarded with high frequency garbage, as are your tweeters, BEWARE!

Active Bessel filters are very easely designed with FilterPro from Burr-Brown; now Texas Instruments; in less than 5 minutes.
ELSO


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