HPX170 XLR Inputs Extremely Hot?

[Kyle_Good]

A few weeks ago, I was shooting with an Audio Technica 4073a short shotgun on a boom pole plugged into the Input 2 on my HPX170. The input was set to MIC, phantom power was on, ALC was on, and the sensitivity was set to -50dB in the menu. There were some loudish dialogue scenes, and in order to keep the shotgun from peaking I had to turn the levels down so far that any more would have basically cut the signal. The levels looked fine, peaking into the red occasionally but I figured the ALC would catch it. However, reviewing the footage in Premiere CS4 it seems the audio STILL clipped.

A week after that, I was shooting a reality pilot and had a wireless receiver plugged into the camera, and ran into the same issue. We turned the levels on the receiver all the way down, and it was still WAY hot coming into the camera, with the level knob as far down as it would go, without cutting off the signal completely.

Am I missing something here? I own an Audio Technica AT897 short shotgun and have never run into this problem. I usually set the levels around 12 to 1 O'clock with it and it works perfect.

Thanks!
-Kyle

[journalist]

I have 200 from 2006 which works fine, but 170 from this year has somewhat different adjustmentcurve in those Audio knobs. Just made interview using AKG PR40 wireless system witn normal non-phamtom mike, same as usual. Reveivers volyme was about 20 % up from zero (the distance was only 6 meters). Well the difference compared to 200 seemed to be that I was forced to turn cams voice knobs almost zero to avoid klipping. The scale seemed to to be somewhat steep not like it mights have been in 200. Havent really compared though. Recording was alright anyway.

jussi

[Kyle_Good]

Funny thing, the same day I was using the 4073a we also plugged it into an HVX200 that we were shooting with. I had to turn the HVX up to probably 9 or 10 O'clock on the dial to get a good level. I guess the HPX170 is just more sensitive? It frustrates me because the ALC didn't seem to help: while it prevented the levels from clipping, they still distorted when they reached its imposed limit of around -4dB.

I also tried setting the input to LINE and turning up the levels a lot, but then the levels barely even registered.

-Kyle

[DJDecay]

A few weeks ago, I was shooting with an Audio Technica 4073a short shotgun on a boom pole plugged into the Input 2 on my HPX170. The input was set to MIC, phantom power was on, ALC was on, and the sensitivity was set to -50dB in the menu. There were some loudish dialogue scenes, and in order to keep the shotgun from peaking I had to turn the levels down so far that any more would have basically cut the signal. The levels looked fine, peaking into the red occasionally but I figured the ALC would catch it. However, reviewing the footage in Premiere CS4 it seems the audio STILL clipped.

A week after that, I was shooting a reality pilot and had a wireless receiver plugged into the camera, and ran into the same issue. We turned the levels on the receiver all the way down, and it was still WAY hot coming into the camera, with the level knob as far down as it would go, without cutting off the signal completely.

Am I missing something here? I own an Audio Technica AT897 short shotgun and have never run into this problem. I usually set the levels around 12 to 1 O'clock with it and it works perfect.

Thanks!
-Kyle

Clipped audio is clipped audio. Best way to get audio into the HPX/HVX via the XLR connectors is in LINE mode and use a separate pre-amp/mixer for the MIC and Shadow Power. Possibly this mixer can have a soft knee compressor on it, but it won't save you from clipping in this intermediate device. However it will save you alot of grief playing with levels on the XLR plugs straigt on the HVX.

For even better results, use a different device than the HVX/HPX to record the audio. Like a Zoom H-4 and record at 24bit/96khz.

I never liked the practice of sticking a Hot Mic into the XLR jacks of the camera, never worked out well, also it ties your boom guy to the cam, if wireless more problems.

Also do yourself a huge favor and don't repeat the mistake a buddy of mine made one time. If you do go the XLR CAM route - Monitor the audio levels via the cameras headphone jack, not from the mixer/board or the wireless transmitter, it can sound fine on it. Someone used some lavaliers, on the headphone out on the reciever sounded great, on the XLR into the Canon they were using, barely audible.

The MIC preamps on the HVX/HPX are not good, don't bother with them. You'll be watching your V/U meters rather than framing.

ALC has a specific reaction time, if the POP or sybilant is below is too quick - it will allow it to clip without lowering level. Plus sticking something like that in flattens your sound landscape, and alows the virtual noise floor to travel up during quiet moments, so your background/room comes in and out based on the loudness of someones voice or deigetic sounds, annoying to work with in POST (sounds like a VBR encoded MP3 file), and will require heavy gating and possibly looping some of the dialogue.

It will give you no room to work with in the POST. A good digital comp/limiter in the signal chain (what ALC is not) will also create audio latency in the signal chain, this is something you don't want. For it to react it needs to look ahead for a certain amount of samples (ms) to be able to see what volume the audio is.

Zoom H-4 has saved me from bad audio numerous times, with and without a boom and field mixer.

Oh an when using line make sure to differentiate between +4 balanced / +0 consumer / and -10 equipment.
Matching it is always best practice.