GH4 Panasonic discovered a fix for the audio buzz!

Panasonic network has been notified and all technical assistance centers are aware of the issue, I can guarantee you from my own experience. This has been confirmed by the technical department in Portugal. There are problems with the resistance part which should be replaced, but only the units up to a certain serial number.

This information is directly coming from the brand representative, and was provided personally to me. I am not allowed to post which serial numbers need to be serviced or not. Even though, I've been enlightened for the subject matter. Once I am directly in touch with the technical staff member who advised me on topic, if I can be useful to anyone, don't mind to post your serial: only first five digits are necessary to know, accordingly my source.

Hope this helps,

E :-)
 
Just got my GH4 back from the Austin, Texas repair facility today. Took about 3 days for them to do the fix. Haven't had a chance to test the audio yet.

Sent: Thursday, Aug 7th
Received: Tuesday, Aug 12th

Sent back to me: Friday, Aug 15th
Received: Tuesday, Aug, 19th
 
Hey guys. I discovered a cheap fix for this issue. I was using a TechPro TP-VM02 mic, which is a cheaper RODE style alternative. I was getting the dreaded buzz. Seeing that the GH4 uses a TRSS style input, on a hunch I plugged in an iPhone headphone adapter that had a built in mic for making phone calls. Interestingly, when I plugged this in, I noticed I could now use the STEREO/SHOTGUN/S.SHOTGUN settings in the menu. When I switched to S.SHOTGUN, I could hear the cheap iPhone adapter mic with no buzz. If I plugged my TechPro mic in, I could hear it when switched to STEREO mode, but with the buzz. Intrigued, I went and ordered this cable, which is for an iPhone and splits the headphone and microphone signals into two separate jacks. Plugged it in, plugged in my TechPro mic into the mic input, and now I can select this mic in either Shotgun or S.Shotgun mode with no buzz. S.Shotgun seems to boost the gain without adding much noise, so I can record at -12db with a strong signal and minimal hiss. Now amazingly, if I plug in another mic into the other jack, I can flip the setting to STEREO and hear that mic with no buzz. And even better, in the manual setting, I can pan between the two mics and record them both! One drawback to the S.SHOTGUN mode is that it only records mono to both channels. Stereo can record to both though. Anyway, thought I'd share and see if this works for anyone else who doesn't want to send their camera in.

UPDATE:

Decided to record some tests, in which you can hear the difference with and without the adapter. The odd thing is, I swear since plugging in the adapter, when I plug the mic straight in again without it, the buzz isn't as bad. I can hear it if I really boost the gain, but I wonder if some internal switch has been flipped. Anyway, using s.shotgun mode is worth it just for the reduced noise. One thing I forgot to mention, you also gain access to wind cut features in the menu with this adapter. I brought each recording into Soundtrack Pro and normalized them to peak 0db.

http://www.pixultronik.com/mictest1.aif
 
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Ed Jeffersen said:
Batutta, why not just send in in for repair?
waiting for mine. .....
Click to expand...

I still might. I'm in Canada, and this isn't a camera I'm depending on for my livelihood so I felt I'd experiment first. Anyway, I'd probably still use this adapter cable even if I get it fixed just to gain access to the extra menu features, which improve the sound considerably in my opinion. Also, thought I'd share the info for people who can't wait the time it would take to ship it out and get it back.
 
Tested with Rode Videomic and buzz is indeed gone after repair. Didn't notice one of the channels being lower/higher than the other. Seems fine to me.
 
kenyee said:
Did they say when the new fixed ones are going to the big retailers?
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They are already at the retailers... Only certain serial numbers have the issue. Send me a private message, I'll be able to advise you. Moreover, I'll also be able to sell any Panasonic gear as reseller, so if you need anyone of their products line, please let me know via the same method. Thanks.
 
hey Scottteh
Did they notify you when they received it?
I sent my via fedex and know they received it but havent heard from the actual facility.
Thanks
 
Mine was signed for at their receiving dock on Wed Aug 27th. I knew there would be a delay due to the Labor Day weekend and was not looking for any status email until today at the earliest. A few hours ago I go an automated call (from FedEX, I think) advising a package would be delivered tomorrow. A tracking number was supplied and I should see it "out for delivery" in the morning.

Then I go on "package delivery watch". Gonna be glad to get it back!
 
Emanuel said:
Once I am directly in touch with the technical staff member who advised me on topic, if I can be useful to anyone, don't mind to post your serial: only first five digits are necessary to know, accordingly my source.

Hope this helps,

E :-)
Click to expand...
Thank you! I'd love to know whether my GH4 has this problem or not. I don't have an external mic to test it out with, so it isn't important to me at the moment. But in the future I might need to use one, or sell the camera, and it would be preferable to fix it now if necessary.

However, when you wrote "first 5 digits", does that include the letters? My serial number has 2 letters, a digit, 2 more letters, then 6 digits. What do you need?
 
Just plug in anything with a stereo 1/8" connector. Ear buds or even a bare connector. Just having something plugged in bypasses the internal mic and switches to external. Set input level to zero and you should be able to hear the noise on your recording.

kb99 said:
Thank you! I'd love to know whether my GH4 has this problem or not. I don't have an external mic to test it out with, so it isn't important to me at the moment. But in the future I might need to use one, or sell the camera, and it would be preferable to fix it now if necessary.

However, when you wrote "first 5 digits", does that include the letters? My serial number has 2 letters, a digit, 2 more letters, then 6 digits. What do you need?
Click to expand...
 
Ed Jeffersen said:
Just plug in anything with a stereo 1/8" connector. Ear buds or even a bare connector. Just having something plugged in bypasses the internal mic and switches to external. Set input level to zero and you should be able to hear the noise on your recording.
Click to expand...

Thank you, Ed! In all that I have read about this problem, this is the first time I've ever read anyone suggest this.

Unfortunately (but not surprisingly), my GH4 body definitely does suffer from the buzz. It's quite clear and unmistakable. At least now I know.

Thanks again.
 
Finally had some time to run some tests on the GH4 after it came back from Panasonic's service center and having the buzz fix applied.

The good news is that the buzz is effectively gone, or rather reduced to the point that it is a non-issue. This is nice.

Unfortunately, the fix also appears to have made the GH4 quite a bit noisier, in some cases raising the noise floor by 10dB compared to the GH4 before the fix.

Here are some examples of the noise floor at different audio gain settings:

  • +6dB: -46dB -> -36dB (10dB noisier after fix)
  • -9dB: -55dB -> -51dB (4dB noisier after fix)
  • -12dB: -57dB -> -52dB (5dB noisier after fix)

It's interesting to note that the GH4's pre-fix -9dB setting is actually quieter than its post-fix -12dB setting.

The other strange side-effect I observed is that each of the GH4's audio channels records at a different level, despite sending the same signal to both channels.

For example, here's a -12dB test tone sent to the GH4 using the Tascam DR-60D:

  • Channel 1 (L) Level: -12.2dB
  • Channel 2 (R) Level: -14.9dB
  • Variance: 2.7dB

It's not a huge variance, but it is quite noticeable and it definitely was not happening before the fix.

Looking at it one way, this means that you need to go through all of your clips on the timeline and set them to use a single channel of audio so that the left/right levels will match up for the viewer.

Looking at it another way, you now have a built-in safety track! :)

I'm sending this info to Panasonic to see if these observations are typical results of the buzz fix. Hopefully they are not.

There are more details and audio samples on the tests in this blog post.
 
Emanuel said:
They are already at the retailers... Only certain serial numbers have the issue. Send me a private message, I'll be able to advise you. Moreover, I'll also be able to sell any Panasonic gear as reseller, so if you need anyone of their products line, please let me know via the same method. Thanks.
Click to expand...

I just tried and it said you've reached your PM storage limit. :(
 
The GH4 has high quality internal preamps, especially compared to DSLRs and other competitors in the general price range. The audio buzz issue is separate from this fact.
 
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