Sound Level for VideoCam

On Sun, 13 Jul 2008 22:37:30 -0700, "Wayne Smith" <[email protected]>
wrote:

>I have what I hope is a simple question. For our church services we
>frequently have a request by an amatuer videographer to capture a service.
>I'd like to give him a feed from the mixing panel for his audio. The
>panel's output would be at line level which he would input to the vidiocam
>using the microphone input. I can lower the line level at the mis panel,
>but I don't know how best to monitor that level to prevent overdriving the
>videocam. Any advice would be appreceiated.

Can't you switch the output to microphone level? If you got some cash left
and want to provide this service, you could get an attenuator to lower the
audio-levels.
Regarding the actual levels, that should not really be your problem. You
can send out a test-tone to set-up the recording level in the camera, and
after that if you control the levels correctly on your mixer, they should
be allright on the camera. Best is of course to leave a bit of headroom on
the camera, because digital has no headroom.

cheers

-martin-
--
Official website "Jonah's Quid" http://www.jonahsquids.co.uk

"Wayne Smith" wrote ...
>I have what I hope is a simple question. For our church services we
> frequently have a request by an amatuer videographer to capture a service.
> I'd like to give him a feed from the mixing panel for his audio. The
> panel's output would be at line level which he would input to the vidiocam
> using the microphone input. I can lower the line level at the mis panel,
> but I don't know how best to monitor that level to prevent overdriving the
> videocam. Any advice would be appreceiated.

So are you getting acceptable levels now?
Absent any anecdotes of how it is working now,
my first response would be that you need an
attenuator to knock the line-level down to the
mic-level that the camcorder(s) expect.

Some camcorders display audio levels in the
viewfinder (typically the more pro-sumer high
end models). But they likely all have "auto-
level" which adjusts the recording level. This
works ~OK for speech but can make a hash
out of many kinds of music.

But in any case, ALWAYS use good circumaural
headphones plugged into the camcorder to
continuously monitor the audio track. Recording
audio on a camcorder without monitoring on
headphones is like aiming the camera without
looking at the viewfinder.

The kind of headphones I use is the Sony
MDR-7506 (or the consumer version V6).
This is a very popular model for people doing
field recording, both audio and video.

"Wayne Smith" <[email protected]> wrote in message
news:SCBek.4920$np7.2641@flpi149.ffdc.sbc.com...
>I have what I hope is a simple question. For our church services we
> frequently have a request by an amatuer videographer to capture a service.
> I'd like to give him a feed from the mixing panel for his audio. The
> panel's output would be at line level which he would input to the vidiocam
> using the microphone input. I can lower the line level at the mis panel,
> but I don't know how best to monitor that level to prevent overdriving the
> videocam. Any advice would be appreceiated.
>
> Thanks
>

Most consumer camcorders have AGC, which may be effective enough to limit
clipping. The easiest thing to do would simply place an attenuator in-line.
However, one significant concern is ground loops and/or hum. If you want to
have a regular hookup for videographers, you might consider an in-line
isolation transformer plus the attenuator.

"PTravel" <[email protected]> wrote in message
news:6e1j9vF4qrpsU1@mid.individual.net...
|
| "Wayne Smith" <[email protected]> wrote in message
| news:SCBek.4920$np7.2641@flpi149.ffdc.sbc.com...
| >I have what I hope is a simple question. For our church services we
| > frequently have a request by an amatuer videographer to capture a
service.
| > I'd like to give him a feed from the mixing panel for his audio. The
| > panel's output would be at line level which he would input to the
vidiocam
| > using the microphone input. I can lower the line level at the mis
panel,
| > but I don't know how best to monitor that level to prevent overdriving
the
| > videocam. Any advice would be appreceiated.
| >
| > Thanks
| >
|
| Most consumer camcorders have AGC, which may be effective enough to limit
| clipping. The easiest thing to do would simply place an attenuator
in-line.
| However, one significant concern is ground loops and/or hum. If you want
to
| have a regular hookup for videographers, you might consider an in-line
| isolation transformer plus the attenuator.

That would be my solution. If you add an isolation transformer and feed
about -35 db for zero on your board, the video camera's AGC should handle it
fine.

Steve King

Thanks for all the responses. The problem that started my query was a week
ago when the video guy used the feed from the mix board. We lowered the
level until it seemed ok to him. However in playback, the sound was really
messy as only seriously running out of head room in a digital environment
can do. Should he have heard the problem with earphones at the camcorder?
Next time I plan to run the feed through a small radio shack mixer that has
a level meter on it and gettting everything trued up so that if it looks
good on the meter, it will sound good in playback.
"Wayne Smith"

<[email protected]> wrote in message
news:SCBek.4920$np7.2641@flpi149.ffdc.sbc.com...
> I have what I hope is a simple question. For our church services we
> frequently have a request by an amatuer videographer to capture a service.
> I'd like to give him a feed from the mixing panel for his audio. The
> panel's output would be at line level which he would input to the vidiocam
> using the microphone input. I can lower the line level at the mis panel,
> but I don't know how best to monitor that level to prevent overdriving the
> videocam. Any advice would be appreceiated.
>
> Thanks
>
>

"Wayne Smith" wrote
> Thanks for all the responses. The problem that started my query was a
> week
> ago when the video guy used the feed from the mix board. We lowered the
> level until it seemed ok to him. However in playback, the sound was
> really
> messy as only seriously running out of head room in a digital environment
> can do. Should he have heard the problem with earphones at the camcorder?
> Next time I plan to run the feed through a small radio shack mixer that
> has
> a level meter on it and gettting everything trued up so that if it looks
> good on the meter, it will sound good in playback.

It is unlikely that the extra mixer and meter will do you any
good. No mixer (and certainly not a small Radio Shack
model) is calibrated for mic level output.

As most everyone has suggested, you SERIOUSLY need
an attenuator to knock the line-level down to mic-level. And
if you are running the camcorder on the AC power adapter,
then you should also use some kind of isolation transformer
as well (to break any ground loop which will cause hum/buzz.)

A very popular solution is a box that combines attenuator and
isolation transformer such as one of the models made by
Beach Tek. http://www.beachtek.com/ Recommended.

"Wayne Smith" wrote ...
> Thanks for all the responses. The problem that started my query was a
> week
> ago when the video guy used the feed from the mix board. We lowered the
> level until it seemed ok to him.

What does "seemed OK to him" mean? How did he determine
that it was "OK"? Clearly whatever method he used was flawed
as demonstrated by your reported results.

> However in playback, the sound was really messy as only seriously
> running out of head room in a digital environment can do.

Yes, exactly the predictable symptom of over-driving the mic
input with line level. Most of us have been there and done that.

> Should he have heard the problem with earphones at the camcorder?

Maybe. Depends on the camcorder. With many of them, the
sound monitored from the headphones will reflect the distortion
caused by over-driving the mic input. But I wouldn't take it as
absolute gospel. It is possible that the headphone output could
be OK while still distorting during recording. Test recordings
BEFORE the event will help sort out exactly what you are
dealing with. Or feeding a proper mic-level signal is practically
guaranteed to avoid the problem in the first place.

> Next time I plan to run the feed through a small radio shack mixer that
> has
> a level meter on it and gettting everything trued up so that if it looks
> good on the meter, it will sound good in playback.

NO! That is a fundamentally flawed theory. Using yet another
mixer in the path which is also metering line-level output adds
no value to the solution.

What you need is mic-level, not well-metered line-level.

The problem is NOT the output level of the source equipment
(the big mixer, the little Radio Shack mixer, or whatever). The
problem is the input level into the camcorder. And an attenuator
is the specific cure for that problem. There is no reasonable
substitute.