About to buy a GH4 but... but how bad is this noise problem?

[Lasers_pew_pew_pew]

Hi there,

 

I've got my pennies together and I'm going to pick up a GH4 next week, and I even bought the EOSHD shooters guide.

 

Problem... This GH4 audio buzzing I keep hearing about. How bad is it really?

 

Lets say I bought a juice box to have with my GH4, and I was using it to record sound from radio mics from interviews/atmos though my GH4.

 

Are my interview audio going to be ruined? Is it that noticeable or is it a tiny little sound issue?

 

I'm going to be using my camera for short films but also for filming documentary work, and I don't want to have to use a separate recorder and then sync in Avid.

 

I need to know that the sound is going to be ok, if I end up making a feature documentary but need to go back to the original rushes from when I was starting out I need to know I can go back and the audio will be useable.

 

Anyone have any experience of this?

 

Any one have any examples of it that you can hear on footage of someone talking?

[varicam]

Let me check with my gear. I normally record audio externally so it doesn't bother me.

[Brellivids]

I'm equally interested in this aspect. Allso I'm interested in the real bitrates that the camera records in 200Mbit mode. Some have said it's just 50Mbit in the 1080p  200Mbit mode.

[varicam]

I did some rough recording with a Sony PCM-M10 line out into the mic in. Since the Sony outputs a line level signal, I had to turn the mic gain on the GH4 by -8dB. It seems like there is no buzz but the noise floor is higher than direct to recorder. I will try a few more settings and post a comparison.

[jcs]

Here's a Sound Devices preamp using MIC level output into the GH4 with mic level -12dB.  An expander ("Dynamics") filter was used in PPro CC to clean up the audio (including room tone):

[varicam]

Ok. Here is my finding. Even with mic level -12dB, the GH4 mic preamp self-noise is still audible. So that's noise that must be removed in post. Since it's pretty much white noise, any decent noise removal tool should do be able to remove it. As for the buzz, the kind that people complained about, I couldn't replicate it.

[jcs]

The GH4 appears to have an AGC, even with the Limiter set to off. This example show's what the buzz sounds like with a very quiet input (I found the same results + analyzed in Audition. The buzz is over 2x the amplitude of the noise floor and is a triangle wave):

[raf702]

Audio is the least of my worries, there's already several work arounds. Such as setting the internal mic to -12db, when using an external mic. Using lav systems, pre-amp setup like a juicelink/beachtek, or simply using an external/separate recording setup like a zoom h4n, tascam etc.

 

I personally use my Beachtek Premp with an Audio Technica XLR mic without issues. I never really use the internal mic, unless I have no other options. But I typically use the internal mic as a reference guide and not much for anything else.

 

 

[pietz]

im using a rode video mic go in manual movie mode and i have absolutely no problem with audio. everything sounds superb. the base noise is at somehwhere around -54dB with the video mic go and with the internal mic its at about -50dB.

[Michael1]

I would love to hear some audio where someone either didn't boost it so we could hear it better, and also didn't clean it up so we can hear it at all.

 

How does the noise compare to other cameras (Blackmagic excluded, of course :) ) ?

 

Michael

[pietz]

sorry i have to take back what i said, or at least be a little more specific. today i filmed a talk at my university and really only used the Video Mic Go as a back up and easier syncing. At higher gains the clicky buzz noize is definately there.

 

so stay in the negative gain area and you should be fine, everything around zero to +6dB is annoying as sh*t.