AF101 bad audio hiss

R

rjnicholls13

Member
Hi, I shot my first interviews with my brand new AF101 yesterday. Imported the footage into Final Cut Pro and was really disappointed with the quality of the audio.

I was using a sennhesiser ME66 mic on channel 1 and a senneheiser EW100 radio micropohone on channel 2.

I had used the very same microphones on my trusted Sony Z1 camera just 3 days prior to this and got really good clean sound.

I was wondering whether anyone else has had similar experiences? Both channels were set to mic and the mic power +48 was only set to on for the ME66. The audio settings inside the camera were on LPCM although I tried it on AC3 and it was just as bad.

Does anyone have any suggestions? I would be very curious to know whether all AF101s are like this, or if I could have ended up with a dodgy camera.
 
Hope I'm not stating the obvious, but are you certain you weren't recording with the internal mic?
How did it sound on headphones as it was recorded or played back in-camera?
What were the level meters hitting on the display?
Were your tx and rx batteries new?
 
Many thanks for the reply. Yes, I was definitely using the XLR inputs for recording the sound.
Playing back in camera you can still hear the hiss. Even when the levels are set quite low for recording, when you increase the gain in final cut pro, the hiss rears its head again.
Brand new batteries also.
Anyone else experienced anything similar?
 
Hi Jeff, many thanks for your reply. Yes I was curious to see this thread from a while back.

I've just done a quick little experiment and wonder if you might be able to help? On my Af100 I have plugged in the headphones and put the volume up to 32 (maximum). I have then set the audio channels at 0 (ie no sound being recorded from the microphones). For the purpose of this experiment, this can be done either using the internal microphone or the XLR. After doing this I am hearing quite a bad hiss. When I try exactly the same thing on my Sony Z1 camera, I hear absolutely no hiss whatsoever.

This hiss is then being recorded whenever I shoot anything. Perhaps you could tell me whether you can hear this hiss when your headphones are set to max volume and the levels are set to zero. This would tell me whether it is my camera in particular that has a problem.

Many thanks!
 
You'll get better results running a powered mixer into the AF100 or recording audio separately. The AF100's preamps are decent but nothing like the quality you get with a decent FP33 or the like. YMMV.

Noah
 
Thanks Noah. However, even when the mic inputs are set to line, I'm still picking up this audio hiss, as per my experiment I described above. Do you also hear this when you switch on your camera? It doesn't seem to matter how the microphones are connected to the camera - via a mixer or not - as soon as I plug in my headphones and switch on the camera I can hear it.

I'm hoping that I have a deffective camera because I will be hugely disappointed if I find out that all Af100's suffer from this. Simply put, my Sony cameras I have used for years have never done this. The idea of recording sound separately seems ridiculous to me - surely the whole point of the AF100 was so that it catered for a number of the problems that you experienced using a Canon 5d mark 2 or the like!
 
rjnicholls13 said:
I'm hoping that I have a deffective camera because I will be hugely disappointed if I find out that all Af100's suffer from this.
Click to expand...

Tried your test and heard nothing but 0db quiet. Sorry but I'm afraid it's either operator or camera error and not a widespread AF100 fault.
 
Many thanks for trying this test. This re-assures me that something is wrong with my camera. I will double check by trying out this test on another AF100.
 
Try different impedance headphones, I can hear hiss with poorly matched hedphones on the monitoring circuit but its not recorded.... I use FCP and the audio seems great.
 
For your experiment, can you describe:

For the two channels, are they set to mic level? What is the mic sensitivity
setting set to? .. and do you have phantom power turned on?

These are important. I do notice that when I crank the volume to max that some
hiss does come out. Not surprising since you've cranked the headphone amp to
its max gain. It's not bad .. but you can hear it.

jeff
 
Thanks for trying this Jeff.

I had the two channels set to mic level with the mic sensitivity set at zero - ie both audio gain dials fully turned to the left. The phantom power is turned off on both channels as well. When I listen to this through headphones, or external speakers as I just tried this minute, there is an unnaturally loud hiss.

I hear exactly the same when the two channels are set to line, whether there is a microphone or mixer connected or not.

As outlined, I tried exactly the same experiment on my Sony Z1 camera and I hear no hiss whatsoever. I am fairly positive that what I am hearing on my AF100 is not normal!

Thanks again.
 
If you hear hiss when nothing is attached it's your camera and you should take it in for repair. If you only hear when your mics are attached- probably don't have your levels set just right or your impedances matching. that said, I'd highly recommend a trip to a dealer where you can try your mics and settings on another camera. It's hard for us to walk through every possible reason 'over the phone' as it were but knowing these things and how they go I'd put my money on a bad cable or operator experience level (no offense intended) over a camera fault.

Noah
 
OK .. so there's a mic sensitivity setting on the AF100's menu .. -50 and -60 .. and then there's the gain
controls on the side of the camera. -60 will apply more gain through the mic preamp and raise the
noise floor accordingly.

If you're hearing a significant amount of noise through the headphone monitor amp, and that same noise
is being printed to the audio on the clip, then you've got something very odd going on.

If you would, please, could you post an audio sample from your NLE (either in AC3, WAV or AIFF format)?

Doesn't have to be very long . maybe 3 for 4 seconds. I can run it through my analyzer and see if
the ranges are out-of-whack.

For normal operation, you may wish to see if your microphones sensitivity exceeds that of the AF100.
In such cases, you may need to use a -20db inline pad to attenuate. However, in this case (which no
input at all and the volume set to 0), I don't believe that the mic(s) are the root cause.

jeff
 
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So .. I analyzed your audio clip up to the point where you start to speak. There is some room noise ( bump or something ) that may
elevate the noise floor somewhat.

However, this is about where I measured my camera at with the -50db sensitivity setting and a gain setting about about 4 and a 1/2.

I think the noise floor is approx. -72db .. and from the looks of the phase, your "bump" came from channel 1. I don't know if Panasonic
spec's the SNR on these mic-pres .. but I've found them noisy enough that we use a SoundDevices MixPre for Mic level inputs.

FFT_AF100_FR.png


So ... I don't think there's anything wrong with your camera .. that's about where its noise floor is with the mic-pre.

You can try a -20db pad to see if it makes it better ..

jeff

PS: i converted it to split-mono and you can see channel1 and 2 somewhat independently. Confirms your bump was channel 1 :-) ..
these low frequency things are murder on stereo images... (BTW).
AF100_Split_Mono.png
 
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Thank you so much Jeff for taking the time to do this for me - really appreciated.

I'm desperately hoping that you are wrong that there is nothing wrong with the camera. The AF100 has produced the worst sound quality from a professional video camera I have ever used. This audio hiss is unacceptable and I'm positive that it would not pass a broadcaster's quality control check.

In over 10 years I have never experienced such poor quality sound and the proof really is by comparing it to my old Sony camera which is far far superior.

Here's hoping!
 
i would try an inline attenuator next before abandoning all hope.

that said, i have low expectations of mic-pre's on video cameras ...

jeff
 
Hmmm, I don't get that level of hiss with a Rode NG-2 on my AF100. (I listened to the audio clip). When I get my AF100 back in about a week I will test it again. I recorded an interview recently with the AF100 and I was really happy with the audio results.
 
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