I saw a thread recently on AC about using Audacity to determine what kind of EQ has been used on the music we listen to and generating an opposite EQ filter in jRiver to correct for a hot upper mid-range or bass that is missing in action. This gave me the idea to try doing the same thing in my system as well, using Audacity to get some qualitative data on the EQ applied to the music instead of just stabbing in the dark with the EQ filters built into jRiver.
Analysis by Audacity has shown about 3 bass roll-off filters that are frequently applied to a lot of pop music as well as some jazz. The filters encountered are 12db,18db,24dB/octave usually starting as high as 85Hz and bottoming out at 20Hz where the roll-off stops.
I have had satisfying results using the parametric filters in jRiver to generate filters with a center frequency of 20Hz and +12dB/oct.,+18db/oct.and +24db/oct to counteract the bass cut filter used on many albums. You have to play around with the Q of the filter to achieve the best result. I have had good luck with filters using a Q of .75 although this is definitely a matter of suiting ones taste.
It may also be advisable to set a reduction in overall level of 3db to 6db with these filters, as you may encounter clipping of the player output depending of how hot and compressed the source is. If it has been fire-walled with a lot of peaks nearly hitting 0dB then your corrective EQ may clip the output if it isn't clipping already.
I have encountered a roll-off
36dB/oct on one album
, the Miami Vice TV series soundtrack.
I like the music, but the album has always sounded kind of tinny to me
. There are probably other albums out that have also been hammered but I hope I don't run into very many of them.
A word of caution here, when applying a boost of greater than +12db/oct., you run a definite risk of clipping your amplifier on these bass peaks. Pay particular attention to which filters are engaged as it is very easy to forget that you already have the 12db/oct filter on in the first Parametric Equalizer and then accidently stack it on top of the 24dB/oct. filter in Parametric Equalizer 2 giving you 36dB/oct, which is at least twice what you may have wanted with potentially disastrous consequences if you have the volume jacked up.
YIKES! So far the filter slopes I have most commonly used have been 12dB/oct. and 18dB/oct. If you have a lot of underdamped bass resonances in the room you may need less in the way of bass boost to correct the deficiencies in your favorite recordings.
A little disclosure here, my system, according to REW is flat to 18Hz at the listening position and is pretty flat overall in the bass region. I am also comfortably inside my system performance envelope doing this kind of correction, the speakers have about a 95db sensitivity rating and I have an amp that puts 180watts into a 4ohm load.
I also helps that I am not completely crazy on the playback volume levels. The lease isn't broken yet and the villagers are not gathered outside with torches and pitchforks, so far. YMMV.
Yes, that's my story and I'm sticking to it
Scotty
