On Fri, 2 Feb 2007 14:44:35 -0800 "ronan mcallister" <bass.woofer@xxxxxxxxx> wrote: > Bill, > > >Note that your exponential horn, which has a mouth diameter of about 15ft > and the speaker was almost certainly less than 2ft, which implies and > exponentiation of 2, Since the length is 17', the cutoff frequency is 1/2pi > 8'= 1/48' which is about 20Hz. Ie, your horn speaker will produce very > little > sound below 20Hz. > > Thank you! I'm happy your calcs agree with mine. My original design goal > was physical limit of fc=20hz or thereabouts. Beyond the physical size I > indicated construction, transportation becomes a serious problem, so my hope > was to force the system to work below it's natural limit of 20hz by > equalization, sub-bass boost, etc. This is where I became interested in > linux/alsa, IIR filters etc. > > I don't plan on trying to build a football-field-size horn; I'm fairly > certain I can make the 20hz horn produce the sensation it's working much > lower that that, but if my "experiment" fails, I'd be happy to have a true > 20hz loudspeaker -- pretty sure I'd be one of the few on my block with one. > > My attention turns to what Alsa/Linux-sound can do to help me manage bass > and subbass. > > Rgds, > Ronan > > > Regarding equalization - Ronan, you have already mentioned bruteFIR, and there is also my mbeq_119700 which can be easily rebuilt to have whatever possible from the point of view of FFT spectral resolution frequencies. If you are interested in the latter, I can send you the most up to date source - a bug was recently found and fixed. You can read about mbeq_119700 here: http://dl.ambiweb.de/mirrors/ftp.alsa-project.org/people/sergstesh/README.multichannel_multiband_equalizer.txt . As with any FIR, the lower frequency limit is defined by sampling frequency and buffer length. Regards, Sergei. -- Visit my http://appsfromscratch.berlios.de/ open source project. ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
