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Gear / Technical Help => Post-Processing, Computer / Streaming / Internet Devices & Related Activity => Topic started by: dimm0k on November 30, 2007, 11:31:53 AM
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With a recent recording the overall sound was great, but throughout it has this sort of muddy sound. I've come across some stuff that mentions using a high pass filter to clean it up... is there a specific range to try out and use with Audacity?
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can't resist. are you running schoeps??? ;D
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can't resist. are you running schoeps??? ;D
damnit, you beat me to it!
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schoeps? Not sure what that is, but my gear is a Sony MD player and Church-Audio's mics and 9100 preamp.
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Here's how I do it in AUDACITY: YMMV
Pick a <23 sec.portion of auduo
Use the frequency analyzer: Analyze > Plot Spectrum
Set to LOG FREQUENCY
set to 8192
set to HANNING WINDOW
set to SPECTRUM
roll your cursor over the graph, find any loud peak frequencies in the low end (works for mid- and high-frequencies, too --- though you might want to look at the RECTANGULAR window for these......)
note the peak frequency
Now you have two options to consider ----
(A) do you want a high-pass rolloff, or
(B) do you want to design a notch filter to suck the offending frequency out of there?
(A) high pass filter ----- try using the GLAME HIGHPASS FILTER
(a) Edit > Effect > Glame Highpass Filter ----
pick a cutoff frequenct a little higher than your peak frequency ---- like for a 55Hz peak, set the cutoff frequency to 76Hz
(b) specify the number of poles ---- 1 for a very gradual runoff, 10 for a steep runoff ---- 3 works well
(c) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(d) Edit > Undo > Glame Highpass Filter
(e) Edit > Select > All
(f) Edit > Effect > Glame Highpass Filter
set cutoff frequency and number of poles again
(g) Use the frequency analyzer again ---- lather, rinse, repeat...........
(B) notch filter ----- try using NOTCH FILTER
(a) Edit > Effect > Notch Filter
enter frequency and Q value ------ Low Q = effect on center frequency and some frequencies above and below
(gradual upside-down bell curve, "dull point")
High Q = effect on center frequency exclusively
(tight, tall upside-down curve, "sharp point")
(b) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(c) Edit > Undo > Notch Filter
(d) Edit > Select > All
(e) Edit > Effect > Notch Filter
enter frequency and Q value again
(f) Use the frequency analyzer again ---- lather, rinse, repeat...........
have fun..........use the notch filter technique to erase feedback squeeeeeeeeeals, too...............
VIVA AUDACITY! :happy:
capnhook
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2nd the notch filter
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Here's how I do it in AUDACITY: YMMV
Pick a <23 sec.portion of auduo
Use the frequency analyzer: Analyze > Plot Spectrum
Set to LOG FREQUENCY
set to 8192
set to HANNING WINDOW
set to SPECTRUM
roll your cursor over the graph, find any loud peak frequencies in the low end (works for mid- and high-frequencies, too --- though you might want to look at the RECTANGULAR window for these......)
note the peak frequency
Now you have two options to consider ----
(A) do you want a high-pass rolloff, or
(B) do you want to design a notch filter to suck the offending frequency out of there?
(A) high pass filter ----- try using the GLAME HIGHPASS FILTER
(a) Edit > Effect > Glame Highpass Filter ----
pick a cutoff frequenct a little higher than your peak frequency ---- like for a 55Hz peak, set the cutoff frequency to 76Hz
(b) specify the number of poles ---- 1 for a very gradual runoff, 10 for a steep runoff ---- 3 works well
(c) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(d) Edit > Undo > Glame Highpass Filter
(e) Edit > Select > All
(f) Edit > Effect > Glame Highpass Filter
set cutoff frequency and number of poles again
(g) Use the frequency analyzer again ---- lather, rinse, repeat...........
(B) notch filter ----- try using NOTCH FILTER
(a) Edit > Effect > Notch Filter
enter frequency and Q value ------ Low Q = effect on center frequency and some frequencies above and below
(gradual upside-down bell curve, "dull point")
High Q = effect on center frequency exclusively
(tight, tall upside-down curve, "sharp point")
(b) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(c) Edit > Undo > Notch Filter
(d) Edit > Select > All
(e) Edit > Effect > Notch Filter
enter frequency and Q value again
(f) Use the frequency analyzer again ---- lather, rinse, repeat...........
have fun..........use the notch filter technique to erase feedback squeeeeeeeeeals, too...............
VIVA AUDACITY! :happy:
capnhook
^^^ This is worth a post in the Archive section on Audacity. ^^^
DSP is fun and useful.
I always start my low-end shaping by putting a deep shelf at about 30 to 40 Hz and below, down about 40db. Lopping off the subsonics from the live environment can make for a clearer overall sound.
As always, YMMV
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Here's how I do it in AUDACITY: YMMV
Pick a <23 sec.portion of auduo
Use the frequency analyzer: Analyze > Plot Spectrum
Set to LOG FREQUENCY
set to 8192
set to HANNING WINDOW
set to SPECTRUM
roll your cursor over the graph, find any loud peak frequencies in the low end (works for mid- and high-frequencies, too --- though you might want to look at the RECTANGULAR window for these......)
note the peak frequency
Now you have two options to consider ----
(A) do you want a high-pass rolloff, or
(B) do you want to design a notch filter to suck the offending frequency out of there?
(A) high pass filter ----- try using the GLAME HIGHPASS FILTER
(a) Edit > Effect > Glame Highpass Filter ----
pick a cutoff frequenct a little higher than your peak frequency ---- like for a 55Hz peak, set the cutoff frequency to 76Hz
(b) specify the number of poles ---- 1 for a very gradual runoff, 10 for a steep runoff ---- 3 works well
(c) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(d) Edit > Undo > Glame Highpass Filter
(e) Edit > Select > All
(f) Edit > Effect > Glame Highpass Filter
set cutoff frequency and number of poles again
(g) Use the frequency analyzer again ---- lather, rinse, repeat...........
(B) notch filter ----- try using NOTCH FILTER
(a) Edit > Effect > Notch Filter
enter frequency and Q value ------ Low Q = effect on center frequency and some frequencies above and below
(gradual upside-down bell curve, "dull point")
High Q = effect on center frequency exclusively
(tight, tall upside-down curve, "sharp point")
(b) apply the filter ---- check it out with the frequency analyzer again ----- when it's AOK, then:
(c) Edit > Undo > Notch Filter
(d) Edit > Select > All
(e) Edit > Effect > Notch Filter
enter frequency and Q value again
(f) Use the frequency analyzer again ---- lather, rinse, repeat...........
have fun..........use the notch filter technique to erase feedback squeeeeeeeeeals, too...............
VIVA AUDACITY! :happy:
capnhook
Awesome post! I can't wait to try this out. Allot of my recordings I am very happy with except a slightly muddy feel to them......hopefully this will do the trick. Thanks again for the tip.
EDIT: I can't find this function on my Audacity (1.2.1). There is no Edit > Effect selection. Also there is no Effect > Glame Highpass Filter selection. Is there a different version or add-on that I need? TIA
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I downloaded version 1.2.6 back in July......it has been running rock-steady. A whole bunch of plug-ins came with the version I downloaded. A fresh download may do the trick. Thanks..
Kevin
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I downloaded version 1.2.6 back in July......it has been running rock-steady. A whole bunch of plug-ins came with the version I downloaded. A fresh download may do the trick. Thanks..
Kevin
I noticed that 1.2.6 is for mac ("PPC") and 1.2.5 is for mac with ("Intel"). I assume that the Intel one is for a mac with an Intel chip, but I'm not sure what the PPC means....any idea?
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nice thread. thanks for the info
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I noticed that 1.2.6 is for mac ("PPC") and 1.2.5 is for mac with ("Intel"). I assume that the Intel one is for a mac with an Intel chip, but I'm not sure what the PPC means....any idea?
PPC = Power PC = Motorola & IBM chips (G3,G4,G5,etc. . . ) = pretty much anything 10-15 years prior to the intel switch.
-jay