Thread: AUDIO PULSE GLITCH ON RED SCARLET

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  1. #1 AUDIO PULSE GLITCH ON RED SCARLET 
    Senior Member Stelios Kokotos's Avatar
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    Hey,

    Just wondering if anyone has encountered an audio glitch that sounds like subtle but frequently occurring crackles in the RED Scarlet MX camera audio? On the spectral frequency display in audition the noise looks like sharp pulses. This only has appeared recently and is across both the camera inputs. The mic inputs are not peaking and all else seems normal.

    https://photos.google.com/share/AF1Q...hfX0JLLVNFZ1JR


    Thanks!
    Stelios Kokotos
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  2. #2  
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    How is it being fed into the camera? A-box? If so, try another a-box/3.5-to-XLR adapter or pipe in a 3.5mm directly.

    Was it wireless audio/mics? Cause sometimes that pulses too (when the batteries ares low or There’s lots of radio chatter).
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  3. #3  
    Senior Member Stelios Kokotos's Avatar
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    Hey Mike,

    Thank you for your reply and information!

    The connection is directly into the 3.5mm mic inputs in the front of the camera using 3.5mm to XLR adapter cables. On the shoot I initially used a G3 wireless system for interviews but if I remember correctly for the main event I used two wired shotgun mics positioned near the stage. Given the nature of the location I imagine that there may have been a few wireless systems operating for the musicians. i also noticed the glitch when recording a performance at another location where the singer was using a wireless dynamic mic and my proximity to her was only a few meters. The glitches occur at frequent and not always constant intervals across both channels which has me wondering if they are actually being generated by the camera itself.

    Thanks again for your help!
    Stelios Kokotos
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  4. #4  
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    Hm. Definitely seems fishy. I'd definitely try removing all variables (so not wireless, and in a relatively low-wireless/radio interference environment, two different mics and cables if you have them) and then test it again.

    Similarly, if you have another camera/audio recorder, test that with the same microphone configuration on both the RED and the other cam/recorder at the same time/place to see if it pulses too (if not, it could be camera.)

    Are these set to balanced or unbalanced? Do you have the internal limiter on (it's not the best, so leave that unchecked)? Is the pre-amp cranked or low (~40db)? Is phantom power on or off?
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  5. #5  
    Senior Member Stelios Kokotos's Avatar
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    Hey Mike,

    Appreciate your feedback!

    I did the following in a low radio interference environment (my home):

    1) Unplugged the cables entirely and turned off the limiter and phantom power ---- The recorded signal was absent of the pulses.
    2) Hooked up 2 shotgun microphones (NTG3 and MKH-416) with phantom power and tested with the limiter on and off ---- The pulses were present on both channels. Although regular there was no clear pattern other than they seemed to occur more frequently (but not exclusively) when there were loud sounds / clipping or the gain was high.
    3) Changed the cable on one microphone whilst leaving the other channel unplugged, turned off my phone and removed a WiFi device that was in the room ---- The pulses were present in the channel with the microphone and the other channel had a couple of pulses that sounded like phone interference.

    Thank you for your help!
    Stelios Kokotos
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  6. #6  
    http://www.reduser.net/forum/showthr...+audio+popping

    It looks like the latest firmware fixes this issue on the helium. Hopefully on your camera as well.
    Mike McEntire
    Mack Dawg Productions
    Oceanside, CA
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  7. #7  
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    Thanks Mike, but he's rocking a DSMC1 Scarlet-MX. Still might be worth reloading the latest firmware, though.

    Stelios, it certainly sounds like the camera. If I'm reading correctly, specifically with phantom power on. Do you have a non-phantom powered mic you could try? (just to see if that's the case). At this point, it might be a matter of just knowing when it happens and avoiding that situation. Did this start happening out of the blue recently?

    Another odd question, but are you using an EVF or LCD? If EVF, try an LCD. Also, it could still be the cables (if they're the same and/or cheaper ones). If you really wanna button it down, find a local reduser with a Epic/Scarlet (and audio set up) and try their configuration on your camera (and vice versa).
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  8. #8  
    Senior Member Stelios Kokotos's Avatar
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    Thanks Mike and Mike P. for your help!

    Today I hooked up 2 x NTG2 mics that are battery powered. With the phantom power and limiter off I tried the mics in balanced and unbalanced modes. The pulses/clicks are still present.

    I only noticed the glitch relatively recently. It is very subtle so it is possible that it was there previously but went unnoticed. It sound like low amplitude crackles or pops and it is not really visible in the regular waveform graph. It is only when I open the audio in Audition and use the Spectral Frequency Display do I really see it 'stamped' on the graph, essential across all frequencies. To clean it up I need to use the spot healing tool on each iteration, which is fine for short phrases but not really practical when recording audio for long periods of time.

    Mike I will read through the thread you linked.

    Mike P. I am using the LCD as I don't own an EVF. I will swap the LCD cable to eliminate the LCD cable as a potential cause.

    It may still be cable related but it seems more and more likely that it is the camera.

    Unfortunately I have not been in recent contact or aware of any local DSMC1 users. I will try reloading the firmware.

    Thanks again for your help guys!
    Stelios Kokotos
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  9. #9  
    Senior Member Michael Winokur's Avatar
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    How often is it happening? I find that any movement of the 3.5mm connectors causes noise. Touching the wires is enough. I'm considering some way of taping them in place.
    Epic #4048 Pharaoh
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  10. #10  
    Senior Member Stelios Kokotos's Avatar
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    Hey Michael,

    Thanks for your feedback!

    This is something I have noticed recently but as it is a subtle effect it may have been present and unnoticed in the past. During my tests there was not really any movement near the connectors and the glitches are really clean, as if 'painted' electronically on the waveform. The only time I didn't notice the glitch was when the cables were not plugged in to the camera and I had turned the phantom power and limiter off.

    I'm beginning to suspect the problem may have something to do with the WiFi in the camera or other internal RF emission influencing the analogue stage of the pre-amp.


    Thanks.
    Stelios Kokotos
    Producer / Director
    https://www.facebook.com/Mysticalguidesstudiospage/
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