| Electronics > Projects, Designs, and Technical Stuff |
| Graphic Equalizer Project. |
| << < (3/5) > >> |
| boB:
oPossum's gyrator circuit is a very good way to go. Much more than 10 bands done that way though and you may very well run into some problems as JS mentioned. I seem to remember the problem was more noise but interaction may be another issue. The "Q" and center frequency of the filters should be done correctly as well. If you say, boost or cut all of the sliders, the overlap of two adjacent filters should be at their -3dB point so it comes out flat response. I know there are 10, 20 and 30 band ISO center frequencies (and Q ?) but I don't know if there is or was one for 15 bands. These days, I kind of like the DSP method idea. boB |
| JS:
There are 15 bands eqs, 31 being the third of octave evenly spaced bands covering the whole audio range, 15 is not so hard to see as half that many bands, the frequencies would be different in each decade, as expected but covering the whole range two thirds of octave at the time. I think it's more common than 20 bands. I don't think they need to sum perfectly at full boost our cut, would be nice but in analog design is pretty hard to do and not to speak with gyrators where the q would bet different for boost and cut. JS |
| Ronaldo95163:
Ive come across the gyrator approach but didnt really give it much consideration for the same reason of it being 15 bands and they may overlap. And yeah I also couldn't really find any standards for Q and center frequencies for 15 bands more than just some pictures of software 15 band EQs which id post later. Also wouldn't it better to not use the virtual ground approach on the op amps...even the summing one? To me it seems better not to to get the full swing of the op amp on the output. I derived the transfer function yesterday for the MFB bandpass filter which I could use for designing once I figure out what center frequencies to use. And yes the overlap should occur in the -3dB ranges...hoping this works out nice for me as it did for those folks in the vid lol |
| Lee Leduc:
Here's some info you may find useful. "Designing with the LMC835 Digital-Controlled Graphic Equalizer" Chip is obsolete but documentation has some good design info on selecting "Q". Application note attached. Elliott Sound Products has about 10 EQ design projects. http://sound.whsites.net/projects-0.htm#equ Rane has a good free tech library of EQ, and other professional audio processing things. https://www.rane.com/library.html#gpm1_1 |
| Ronaldo95163:
Woa thanks man some really good info there Especially for the band pass filter I managed to find out that its the iso 2666 standard that eqs center frequencies are based on 15-17 band eqs should use bands with 2/3 octave spacing. The freqs for a 15 band eq according to the iso standard are 25 40 63 100 160 250 400 630 1k 1.6k 2.5k 4k 6.3k 10k 16k Couldn't find anything being mentioned about recommended Q for a 15 band how ever. |
| Navigation |
| Message Index |
| Next page |
| Previous page |