I didn't think he was asking for high attenuation of 96kHz.
He seemed to me to be asking for a filter that removed high frequency rubbish and started to turn over somewhere just above 20kHz.
"in 96kHz material" implies that he wants to keep the audio signals upto 96kHz.
He seemed to me to be asking for a filter that removed high frequency rubbish and started to turn over somewhere just above 20kHz.
"in 96kHz material" implies that he wants to keep the audio signals upto 96kHz.
If he meant 96kS/s then that requires passing a 48kHz signal
Samples per second and frequency are quite different.
Members need to learn to speak the "lingo". This is an electronics site and just to ask a question requires some knowledge to present the question without ambiguity.
Samples per second and frequency are quite different.
Members need to learn to speak the "lingo". This is an electronics site and just to ask a question requires some knowledge to present the question without ambiguity.
Well that would be very nice.
But not realistic.
And, given that he disappeared, it's hard to know what he was trying to do.
But not realistic.
And, given that he disappeared, it's hard to know what he was trying to do.
The OP may or may not have been doing it, but asking a question which is not understood by the questioner is quite common on here. When this happens it is very likely that the correct answers will not be understood either. Sometimes we can help the questioner to ask the right question, sometimes not.
Well if you think you've seen it all, look here: http://www.diyaudio.com/forums/lounge/249418-dac-filtering-technique-45.html#post3994369
All the DAC noise is inaudible, but the low pass destroys the sound. Or something.
Jan
All the DAC noise is inaudible, but the low pass destroys the sound. Or something.
Jan
Even though ultrasonic frequencies will not be reproduced on speakers they would still cause intermodulation distortion in the audio frequencies.
A good reason to have basic filtering at every I/O jack is that we live in a world bathed in RF, and every cable can act as an antenna, injecting RF into our circuits, waiting for it to be demodulated, Maybe it's a problem, maybe not, but when it is a problem, I guarantee you there is no simple fix. You'll try ferrite clamp ons and swap among various voodoo selected cables and maybe you'll be happy, maybe not.
I find that for the cost of a 100pF cap and maybe some well chosen ferrite chips on each I/O pin, you can avoid all RFI problems, and also help to knock down ESD problems a bit as well. If you structure things carefully, you won't meaningfully impinge upon the audio signal, but you can knock down the FM band, cellphones, WiFi, and with a little more effort, the AM broadcast band. I just "pay the tax" and use a quality, RF grade 100pF cap with nulls at the cellphone frequencies (~850MHz and ~1.8GHz), the Murata GQM1875C2E101JB12D, and I never have any problems with my circuits. FWIW, these are line level analog I/O lines, so adjust the component values for mike lines and phono etc.
I find that for the cost of a 100pF cap and maybe some well chosen ferrite chips on each I/O pin, you can avoid all RFI problems, and also help to knock down ESD problems a bit as well. If you structure things carefully, you won't meaningfully impinge upon the audio signal, but you can knock down the FM band, cellphones, WiFi, and with a little more effort, the AM broadcast band. I just "pay the tax" and use a quality, RF grade 100pF cap with nulls at the cellphone frequencies (~850MHz and ~1.8GHz), the Murata GQM1875C2E101JB12D, and I never have any problems with my circuits. FWIW, these are line level analog I/O lines, so adjust the component values for mike lines and phono etc.
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