DV Info Net

DV Info Net (https://www.dvinfo.net/forum/)
-   Sony HVR-Z5 / HDR-FX1000 (https://www.dvinfo.net/forum/sony-hvr-z5-hdr-fx1000/)
-   -   How does one measure line level? (https://www.dvinfo.net/forum/sony-hvr-z5-hdr-fx1000/485732-how-does-one-measure-line-level.html)

Sam Renkin October 5th, 2010 08:06 PM

How does one measure line level?
 
Well ... I've still got an audio issue after my camera was repaired by Sony. I was on a two camera shoot (with a V1) last week and we were both getting a mono line level feed from a Shure field mixer. It was plugged into Ch 1, but I was routing it to Ch 2 as well. The other camera was getting a nice hot signal ... I was getting barely a whisper. I tried plugging directly into Ch 2, also bumped up the gain to 18db but it was still a very low signal. We even switched feeds/XLR cables, thinking that was the culprit but it wasn't.

This is the same issue I was having on Ch 2 before the repair. Before I go through that again, I'd like to measure the relative line level gain somehow ... any ideas?

Sam

Leslie Wand October 5th, 2010 10:58 PM

don't have my camera to hand at the moment, but have you checked the settings on the panel next (just under) the mic?

not sure why there's two audio control panels in the first place, but....

Adam Gold October 5th, 2010 11:17 PM

"Bumped up the gain to 18dB"? Where? Not on the cam, surely; the Z5 doesn't measure or display audio gain in dB. The only setting on the cam that does is TRIM, and that's for mic only, not line, and anyway it doesn't go up to +18, only +12.

Are you sure the mixer was really putting out line level? Were you on Auto or Manual? If Manual, where were the audio level dials set for each channel? What happens when you switch the LINE/MIC switches near the mic to MIC? First set INPUT 1 TRIM to -18 and then switch the input to MIC. Work your way up the TRIM settings until the sound is okay. Then switch back to LINE and tell us what happens.

Also, did you try swapping headphones?

Leslie, there are two different audio control panels because they do different things and there probably wasn't enough room in any one place to handle all those functions together. The one near the XLR inputs tells the block what kind of device you're connecting to, what to supply to it and what to expect in return. The panel on the side controls channel mapping and volume. And then in the menus there's more stuff that neither of these panels can do.

Leslie Wand October 6th, 2010 01:54 AM

as ever, you're right adam....

since i probably look at the mic block when i unpacked it, made sure it was set to mic, and ditto menu settings according to my needs, i probably haven't looked at either of them a second time ;-)

meanwhile audio from built-in, sony external, and my me80, 66, ev100 all sound spot on i probably wont look at them again ;-)

Rob Morse October 6th, 2010 12:26 PM

I've never had success using the Line Input setting on my Sony cameras. I've never had and issue getting great audio though. I have an attenuator that goes from -10-30 db, and together with the Mic setting, always works perfect for my needs.

Sam Renkin October 6th, 2010 12:35 PM

"Bumped up the gain to 18dB"? Where? Not on the cam, surely; the Z5 doesn't measure or display audio gain in dB. The only setting on the cam that does is TRIM, and that's for mic only, not line, and anyway it doesn't go up to +18, only +12.

Are you sure the mixer was really putting out line level? Were you on Auto or Manual? If Manual, where were the audio level dials set for each channel? What happens when you switch the LINE/MIC switches near the mic to MIC? First set INPUT 1 TRIM to -18 and then switch the input to MIC. Work your way up the TRIM settings until the sound is okay. Then switch back to LINE and tell us what happens.

Also, did you try swapping headphones?"

All good questions, Adam - thanks. I wrote this post without looking at the camera, so I apologize for the mixed reference to gain. I did try elevating the trim to +12 hoping to strengthen the line level signal but wasn't successful. The mixer was indeed putting out LINE level, and switching my camera to MIC level resulted in a very hot (overdriven) signal. I suppose I could have tried your suggestion (use MIC setting with the trim all the way down) but I was frustrated that things weren't working as they're supposed to. The volume control was set to manual, and I rolled it all the way up to get about 30% of max volume on the meters. Setting it to AUTO didn't make much difference. And the headphones were working fine - I switched to the onboard mics and there was plenty of volume.

What perplexes me is that the V1 (which I used to own) was working perfectly using the same source audio. My goal with this thread is to find a true line level signal (test tone or other audio source) to test the LINE inputs with. In addition, I'll need to take that mixer home with me!

Sam

Adam Gold October 7th, 2010 12:13 PM

Quote:

Originally Posted by Sam Renkin (Post 1576181)
I did try elevating the trim to +12 hoping to strengthen the line level signal but wasn't successful.

Right, because as the manual points out, TRIM is only for MIC -- when you switch the input to LINE the TRIM controls do not work.

Without seeing the cam we can't know if it is truly broken or if something is set wrong. And that the V1 works fine doesn't mean much because we don't know all the settings on that one either, and anyway the audio sections of the two cams could be, and likely are, quite different.

In a big city like Atlanta I would think there would be a camcorder repair place that could at least do a quick test while you wait, without the need of sending the thing off to Sony again.

I wish I could help more. If you're in a situation where you actually have the time and space to set up a mixer and two cams, you might want to consider an external recorder anyway. Doesn't really identify or solve (or even actually address) your issue but it's a workaround. I haven't used the cams' audio tracks for anything but sync for a couple of years now.

Sam Renkin October 23rd, 2010 08:26 PM

Okay, so I decided to test the LINE level inputs on my camera since it appears to be much less sensitive than the V1U I was shooting with before. Here's how I did it:

I took my trusty iPod and attached an audio cable with stereo RCA connectors. I attached these to a pair of XLR to RCA adaptors, and inserted those into the inputs on my camera. I set the inputs to LINE level, and put on one of my favorite playlists. Then I played with the volume on the camera and the iPod.

Yes I know this is an unscientific approach but it still confirmed my suspicion. With the audio levels set to 10 on the camera and the audio set to MAX on the iPod, I was getting about 70% on the VU meters.

I'm hoping this is something that can be fixed with a software or hardware tweak locally in Atlanta rather than sending the camera back to Teaneck NJ again?

Robert Wiejak October 23rd, 2010 11:09 PM

Quote:

Originally Posted by Sam Renkin (Post 1581572)
...I took my trusty iPod and attached an audio cable with stereo RCA connectors. I attached these to a pair of XLR to RCA adaptors, and inserted those into the inputs on my camera. I set the inputs to LINE level, and put on one of my favorite playlists. Then I played with the volume on the camera and the iPod.

Yes I know this is an unscientific approach but it still confirmed my suspicion. With the audio levels set to 10 on the camera and the audio set to MAX on the iPod, I was getting about 70% on the VU meters....

iPod is not the best choice for this test. I don’t have one and I tried to look up the technical details for it on Apple site without any luck. So I can’t tell what type of output it has, but if you consider the fact that the iPod is a consumer product, it should have consumer type of interface/signals. So if it has consumer line level output, that’s -10dBV or 0.316Vrms as a reference level. In professional audio equipment the reference level for a line level signal is +4dBu (or 0VU) and that translates into 1.228Vrms. So if you are getting 70% on the VU meter then that iPod is putting out a lot more then -10dBV, about 0.9V, still not enough to register 0VU on your camera meter.

One suspect for me is your XLR to RCA adapter. Since on XLR side one would expect signal around +4dBu and on RCA side -10dBV (1.228Vrms vs. 0.316Vrms respectively), there may be some attenuation in that adapter. So if that’s true, then in addition to the attenuation, you are going in the wrong direction, RCA (small signal) to XLR (large signal). In other words, you are attenuating the already smaller signal, about -12dB (that’s how much attenuation is needed to go from XLR to RCA and to maintain the respective levels).

The fact that you are getting 70% on the VU meter, tells me that maybe you are starting with a speaker output level. So you are starting with higher voltage, but due to attenuation only 25% of the signal (-12dB) is reaching the other side of the adapter. Let see, 70% of 1.228V / 25% is about 3.5V that's about right for headphones output. It still is just a speculation on my part, but it would explain the levels you are getting.


All times are GMT -6. The time now is 08:42 AM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2024 The Digital Video Information Network