Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uwm.edu!linac!att!pacbell.com!tandem!zorch!sega0!mykes From: mykes@sega0.SF-Bay.ORG (Mike Schwartz) Newsgroups: comp.sys.amiga.audio Subject: Re: Disable low-pass filter on Amiga 500? Message-ID: Date: 24 Mar 91 06:45:55 GMT References: <1391@ssp18.idca.tds.philips.nl> <9103192231.39@rmkhome.UUCP> <1991Mar21.201950.14705@ccs.carleton.ca> Organization: Amiga makes it possible Lines: 31 In article <1991Mar21.201950.14705@ccs.carleton.ca> ags@scs.carleton.ca (Alexander George Morison Smith) writes: >In article <9103192231.39@rmkhome.UUCP> rmk@rmkhome.UUCP (Rick Kelly) writes: >>In article <1391@ssp18.idca.tds.philips.nl> fwvo@idca.tds.PHILIPS.nl (Ferdinand van Ommen) writes: >>>How can I disable the low-pass filter on my Amiga 500? ... >> >>The average human being cannot hear anything above 15khz. Good stereo >>equipment cannot produce sound above about 18khz. It is a simple fact of >>life. There is no reason for you to open up your 500. > >The Amiga audio filter cuts off at 7KHz, I believe. So it is still >worthwhile to disable it. Besides that, the sampling rate has to be >twice the frequency if you want to reproduce sounds of a given >frequency. Even higher sampling rates improve the quality of the sound. >As you may know, compact disks are recorded at a rate of 14KHz. > >- Alex Compact disks are recorded at a rate of 44.1KHz using 16-bit samples for 2 channels (left/right). You are right that higher sampling rates improve the quality of the sound. They also take up lots more memory. I already posted that you can easily turn off and on the filter with software using one instruction in assembler language. Lookup bit #1 of CIA A PORT A in your hardware manual. mykes -- ******************************************************* * Assembler Language separates the men from the boys. * *******************************************************