XH-A1, line level or mic level?

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Petrus

Well-known member
We all know HX-A1 has a bit funny line in levels, with a standard line in levels (like from SD302) you have to set the potentiometers to full open, or just a hair from full to get decent levels. Some people have sounded concern that this can not be right and they rather use attenuation on the mixer and use mic levels in to be able to use the midrange area with the level pots on camera.

Test setup: Loud pink noise from a good stereo system, quiet room, Rode NT-1A super-quiet studio condenser microphone. First pink noise via SD302 to line in, camera pots open, level on SD302 just starting to hit the limiter set at +17 dBVU, then the mixer pot turned down to kill the input (to get the system noise floor). On the second sample the output levels pulled down on the SD302 so that when using mic in the camera pots are at midrange (optimum?). Same pink noise at same levels, also "quiet" recorded after the noise.

Result: The line level gave max peaks at -4.60 dBFS and minimum average RMS at -93.93 dBFS. An amazing dynamic range for a camera, approaching the theoretical limits of a 16 bit system. Almost 90 dB!

With mic levels the peaks were at -3,17 dBFS and with no signal average RMS at -79.21 dBFS. Thus the mic in was 10 dB noisier than the line level even with the pots all the way open with the later.

I will continue to use the line level in, and turn the potentiometers all the way south.

Both results are good, better than you can get with any Nagra...

Shot at SD to use uncompressed PCM audio.
 
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Very interesting and thanks for report this. I ended up using mic in on the A1 and the 302 output set to -50 mic level. Pots on A1 were midrange. I personally never run something with a pot wide open.
BTW, after 25 years dealing with audio and video equipment, this is the first time I've seen a piece of gear that you turn the pot COUNTER CLOCKWISE TO INCREASE GAIN.
Really stupid.
 
Petrus, I don't understand much of the technical terms but this was a problem that I ran into repeatedly during my last project when no matter what adjustment I make to the A1 my soundman's 302 would not give me decent levels on line in.

Did you have the audio control on the A1 set to manual and crank all the way up? Or was it left midway and let the mixer audio control take care of it? I would appreciate hearing your settings, thanks!
 
HX-A1 audio on manual (of course) and open all the way, those little arrows pointing down. When setting up with a mixer you have to use the test signal (at least the standard 0 dBVU/-20 dBFS and possibly also full level test signal), how else would you know if the levels are optimal. With the 0 dBVU signal the HX-A1's meters should show the last mark before the green -12 dBFS marker, with full level test signal (accessed from SD302's setup menu) the very last segment should just light. With HX-A1 this means you have to turn the pots all the way open* with line in, no attenuation. With the limiter turned on on SD302 there is no way you can clip the camera inputs (if the soundperson knows anything about levels).

My test showed that there is no need to be afraid of the full open pot position with line in.

*) or just a few degrees from all the way, but with good limiters on the SD302 it really does not matter, easy to turn all the way.
 
Thanks for that info Petrus, I'll have to do some more tests with that when I had the chance but during the project I was never able to get audio level to hit -12db or anywhere close to that, even when the mixer was sending very hot signal. It was audible but very low.
 
I can definitely recall that I was sending 1kHz @ 0dBu to the line ins of the A1s and seeing that the level bar was hitting either 1 or 2 below the -12dbFS bar. What does this contribute to? I didn't attenuate the outputs nor lower the gain of my inputs while the fader was set to unity. As far as I know, the input pots on the A1's doesn't need to be turned up because it's accepting line level rather than mic level. No matter what we did, dialed up or down the input pots, the level stayed constantly at about -20dbFS (which is 2 bars below the big green bar).
 
Audio level pots affect also the line level input, just try it, and they have to be all the way open to get standard levels (of about -1 dB from full, no matter). If you get 0dB test signal to hit -20 dBFS level on the camera, you are spot on...

The first color marker on XH-A1 is -12 dBFS, the first left of that is -20dBFS if my memory serves.
 
I believed during the last week and a half or so of shooting the level knob on the A1 was turned all the way up with no appreciable improvement in level going in. Alan and I tried every setting we can think of on the camera without effect.
 
jade8472 said:
I believed during the last week and a half or so of shooting the level knob on the A1 was turned all the way up with no appreciable improvement in level going in. Alan and I tried every setting we can think of on the camera without effect.
Click to expand...

That's what I thought. There was this one time during the first few days of shooting we selected mic in rather than line in and worked alright, but the both of us preferred line in, but no help.
 
For normal dialog around -20 to -8 dBFS, when the SD302 limiters (set to +17 dBVU in mine) start cutting in the peak levels are about -4 dBFS as measured from the resultant audio file (+12 and +16 leds blink on SD302).
 
Petrus said:
For normal dialog around -20 to -8 dBFS, when the SD302 limiters (set to +17 dBVU in mine) start cutting in the peak levels are about -4 dBFS as measured from the resultant audio file (+12 and +16 leds blink on SD302).
Click to expand...

You're right, however, I didn't touch the output attenuation so the levels should be much hotter than what you're getting. Maybe it's the camera, maybe not. What settings were you using on your A1?
 
Checking back at the level from the camera, I was getting -30 to -25 db, never more than that. This is from the day when I remembered Alan telling me that he's sending me the hottest level he can managed. Pots on the A1 was at maximum.
 
I do not use any output attenuation on SD302, which in this situation would be foolish anyway. No attenuation anywhere, as we are barely getting a full level signal, but we are (I am, that is) and it is high quality.

Walking through this:

- you have no attennuation on SD302 (no warning light at the output end of the box)
- you send test signal set to 0 and/or +20 (full scale) to XH-A1 with line in, no att, and pots all the way open = pointing down. This should give the first marker before the green marker with standard tone and all segments lit with +20 db full scale test signal.

If this does not happen there is attenuation somewere along the system, in the cable, wrong setting somewhere, or either SD302 or the cam is out of whack.

With those settings the orange level SD302 signal (0 to +12dBVU) like strong dialog hovers around the green -12dBFS marker on the XH-A1 just like it should.
 
I used -20 on cam, not -12 for setting level. I found those audio switches not really intuitive on the top of the cam. I prefer Panasonic cameras for audio.

Very funny about the water faucet... that's a keeper.
 
I made some more tests, not relying on the meters only, which are not very accurate visually on the XH-A1.

I recorded the full level 1 kHz signal and 0 dBVU standard 1 kHz signal from SD302 on tape with audio potentiometers full open, clean line level from SD302. These should record at 0 and -20 dBFS resp.

Result: clipping level signal gave 0 dBFS peak value with NO CLIPPED SAMPLES (Auditon analyze function)! That is a PERFECT score!

Standard tone at 0 dBVU gave -20.41 dBFS levels, almost perfect.

With over 90 dB S/N ratio in real life and perfect line level match* I have no complaints about SD302/XH-A1 combination.

*) and easy at that, just turn the pots fully open.
 
My concern with the A1 on line level that it would use a resister pad and the signal still went through the mic pre on the cam and thus would be noisey with the pot wide open using line in. Not the case, right?
 
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