Hi SeekUp40 and All,
Setting a high-pass filter (ie. bass roll-off) has always been a point of discrepancy for many people.
My personal sentiment is that I would rather use an HPF when recording then in post. Since low-end is often exaggerated for the benefit of our ears which do not perceive low-frequency as well as high frequency, recordings can become excessively bassy. Further, since the low frequency information contains a lot of energy that will drive our levels on our recorders, it will force us to set our overall levels lower than desirable, especially if we plan on taking out the bottom-end anyway. This is particularly valuable when recording at 16-bit since we are giving up 1-2 bits to the bottom-end that we will later through away either in editing or with an EQ. If we use an HPF in the recording process, we get better resolution for the mids and highs since we can then set our levels to peak in the –2dBfs range for the higher frequency content as opposed to doing so for the low-end (which we may not want later anyway and may be 6-12dB hotter than the mid through high-end).
I am totally sympathetic to the idea of trying to most accurately represent what we hear, but a HPF is one of the tools that many of us have on our pre-amps. Utilizing our tools to the fullest potential gives us the best opportunity to achieve the results we are after. It really depends if you are trying to get an exact representation of how your mics “heard” the show, how you heard the show, or what will be the most listenable on your playback system and/or the playback system(s) of others.
The obvious disclaimers apply—your ears will the best judge and this will vary with equipment and source material.
Generally, if I’m running Schoeps, AKG 480’s, or a large diaphragm mic, especially with a bass heavy band, like Panic or Mule, I will use a gentle roll-off 6dB at 50Hz or 75Hz. For mics like DPA, Neumann, MBHO or Earthworks, I won’t typically use a HPF unless the band/venue is really bassy or boomy. In most of these cases, I would be running a V2/V3.
If you are running with the mics close to one column of P.A. in closer to it than you are to the subs, which are usually stacked on the stage, you may not find it necessary to run the HPF.
Another interesting anomaly can be the low frequency coupling that occurs in the middle. There is roughly a 6dB boost of low frequency (under 100Hz) that you will notice at dead center. Go to middle, listen, step 3-4 feet to either side. Notice the difference. Go back to the middle. A typical filter of 6dB/octave at 75Hz serves quite well in neutralizing the build up. You may actualy find the results more listenable than just capturing exactly what was there.
I hope this is helpful.
Happy Recording,
Marc
Topic: Setting Bass Roll Off (Read 14452 times)