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Phase Canceling Audio
So I capture into the G5 via a Kona card, I pass the audio through a pre-amp Mackie 24 bus board…. problem is in FCP 4.4 EDU Version, when sending a stereo signal into a single input when the balance is centered, a get a phase lock where there is low, or no audio. When I pan it in either directon, it comes in fine. same is I use two inputs for the stereo signal.
Help please… is this a KONA/FCP 4edu problem????
DM
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6 Replies
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WHen you open the log and capture window, you should be able to select if you want to capture dual mono (such as you have done) or stereo.
Jeremy
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It’s probably your cables. Check that first.
Have you tried mixing it to mono in the mixer first, and then sending out the mono signal to the Kona? -
If you are connecting to and from your mixer with XLR connectors, reversing pins 2 & 3 at one end of one cable will throw the phase out 180 degrees resulting in the sound you hear. Pin 1 is ground.
I don’t remember seeing a phase reversal switch in FCP, so your problem is probably your cables as Chris pointed out. You can quickly test this with a continuity tester. Disconnect the cables and test the continuity between all the pins: 1 to 1, 2 to 2 and 3 to 3. If you don’t have continuity from 2 to 2 or 3 to 3 then one pin is connected incorrectly at one end. Then, you’ll have to open the connectors at each end and look to see where the problem is.
John
Dual 2.5 G5 4 gigs RAM OS 10.4.8 QT7.1.3
Dual Cinema 23 Radeon 9800
FCP Studio 5 (FCP5.1.2, DVDSP4.1.1, Comp2.3, STP1.1, Motion 2.1.2)
Huge U-320R 1TB Raid 3 firmware ENG15.BIN
ATTO UL4D driver 3.50
AJA IO driver 2.1 firmware v23-28
Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neuman U87s, Genelec Monitors, PrimaLT ISDN -
[Chris Babbitt] “It’s probably your cables. Check that first.”
Since this comment is probably correct, it deserves more explaination.
If your Left and Right balanced audio cables are wired differently you will get one channel inverted in relation to the other so when you sum them they cancel out. If each channel by itself is OK but together they cancel, this is what’s happening. A phase invert switch on one channel of your mixer could be causing this too, so check that first.
As to checking the cables, Whether they are XLR to XLR cables; XLR to 1/4″ Tip/Ring/Sleave plugs or XLR to RCA phono plugs the internal wiring must match on the Left and Right cables. You can check with a continuity tester or sometimes you can open the connectors and check visually. Or just substitue a known good cable set.
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I hate when that happens. But well put, John. And you beat me to it by 41 seconds.
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I know what you mean, Larry. However, you brought up two good additional points about a phase switch on the mixer and 1/4″ TRS plug wiring.
John
Dual 2.5 G5 4 gigs RAM OS 10.4.8 QT7.1.3
Dual Cinema 23 Radeon 9800
FCP Studio 5 (FCP5.1.2, DVDSP4.1.1, Comp2.3, STP1.1, Motion 2.1.2)
Huge U-320R 1TB Raid 3 firmware ENG15.BIN
ATTO UL4D driver 3.50
AJA IO driver 2.1 firmware v23-28
Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neuman U87s, Genelec Monitors, PrimaLT ISDN
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