On Tue, May 17, 2011 at 12:09 PM, Mark E. Skeels wrote: >> Have a look at a couple of recent issues of Circuit Cellar. There are >> two projects this year where a dsPic has been used to make an audio >> frequency analyser, displaying on a LED bargraph. The most recent one >> is a stereo one. These should give you a feel for doing DSP on audio. >> I had assistance from a guy to set up a sound system in a church which >> was almost a pentagon shape on the ground plan (the sides were not all >> equal length) and this created all sorts of echo problems. He used a >> similar analyser made out of a number of analogue filters, with about >> 5 or 6 channels. We fed a white noise source into the speaker system, >> and used a microphone at the normal speaking position fed into the >> analyser. The frequency response was then adjusted using the equaliser >> on the speaker system so that the displayed frequency response was >> flat. It made a big difference to how much level you could before >> feedback, as it meant there wasn't a frequency with a highish Q 'hump' >> in the response. > > Cool! I will definitely check that out. > > Mark > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > Ive used a similar device, pretty sure it was behringer as the styling of the front panel was the same, but may not be the same device as this http://www.behringer.com/EN/Products/DEQ2496.aspx You buy a "reference" omnidirectional mic, hook it up the the mic input, and it plays pink/white noise (as desired) over the speakers, and it can either auto-level the response of the whole system, or just show the results on the real time analyzer for you to tweak as needed. Feedback destroyer was nice, though violins tended to irritate it, so I mainly left it on manual, with high Q (10-30+iirc) band-stop filters on problem frequencies, leaving the parametric and graphic EQs free for other stuff. For your situation, I'd expect a the reference mic mounted where you want your mic to go, and a speaker where the usual sound emitter would go. An EQ can knock down peaky frequencies and bring up low ones, but it cant fix cancellation due to reverb, and reverb in general making the sound quality poor. Damping if possible would definitely be the most effective place to start imo. As others said, if you can get fabric drapes etc up that helps, but also the drapes can conceal ugly stuff such as more effective sound absorbing matl etc... --=20 Jonathan Hallameyer --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .