Xref: utzoo rec.audio:30105 comp.dsp:1461 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!netcom!mcmahan From: mcmahan@netcom.COM (Dave Mc Mahan) Newsgroups: rec.audio,comp.dsp Subject: Re: Good speaker + DSP == perfect speaker? Message-ID: <1991Mar23.182932.29276@netcom.COM> Date: 23 Mar 91 18:29:32 GMT References: <1991Mar22.171203.8665@sco.COM> Organization: Dave McMahan @ NetCom Services Lines: 46 In a previous article, jfischer@sco.COM (Jonathan A. Fischer) writes: > > Something that's really caught my interest lately (I suppose >it was after reading a review of the Meridian D6000 "digital speaker") >is the possibility of the following scenario: > > You buy a good speaker with no glaring flaws. Its frequency >response is pretty good, varying +/- a couple of dB over yer basic >40-ish to 20K Hz range. Its phase accuracy varies +/- degrees over >the spectrum (whatever's typical). > > So you buy a programmable DSP "package," containing the DSP >unit (which also performs as a frequency generator), and a mike or >Sound Pressure Level meter. You set up the SPL meter in your >listening spot, press the "setup" button on the DSP unit, and it >commences to send frequency sweeps through your sound system, reads >the levels and the phase response. Finally, using these variables, it >sets up a digital equalization + phase doctoring DSP program which >will transform your sound system, no matter what your room's or your >speaker's acoustical properties, into one with a completely flat >frequency response curve, and with zero phase shift across the entire >spectrum. > > Is this a pipe dream or is it feasible? Sure, it's feasible. How much do you want to spend and how much correction do you think you will need? The only other thing that you have to remember is that your system of amplifiers, etc. must be capable of time invariant response. That means that if you turn up the volume a bit or the amplifier temperature drifts a bit due to a warmer room, your parameters won't drift. This system wouldn't work very well if every time you adjust the volume you get a totally different response curve. The other thing you could never do is move plants or furniture within the room and not re-tune the system. You won't be able to ever get down to a sub-woofer response without having a speaker that is capable of such low bass as well. You could compensate a current system, but don't look at getting concert hall performance with mail-order speaker systems and amplifiers. >Jonathan A. Fischer SCO Canada, Inc. >jfischer@scocan.sco.COM Toronto, Ontario, Canada -dave -- Dave McMahan mcmahan@netcom.com {apple,amdahl,claris}!netcom!mcmahan