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Next: Lectro 211/Sd442 Issue
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External
Since: Dec 26, 2003
Posts: 23
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(Msg. 1) Posted: Wed Jan 28, 2004 8:37 pm
Post subject: Distortion in audio monitor on Panasonic SDX-900
Archived from groups: rec>arts>movies>production>sound (more info?)
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Since we bought a new Panasonic standard def 24P camera, the SDX-900 clients
have been raving about the look. I've been complaining about the audio
monitor because I have been noticing "splashing" on peaks. Finally I found
the cause and solution to this troubling issue.
I did several tests with this camera by feeding +4 into the line level
inputs from a FP33 with a Schoeps mic. As I made sharp sounds, (ha, he, ah
and that sort of thing,) I was hearing distortion on peaks listening to the
camera's return. No matter where I ran the headphone monitor on the camera,
sending normal level, nothing hotter than -5db, would cause this distortion
in the monitor. It sounded like the analog headphone amp was being hit with
too much input. However bad the monitor sounded, the recording was
perfectly fine. No distortion was heard at all.
Today I found that when the camera was first out of the box, I changed one
of the menu settings that caused this problem. In the VTR menu, the second
audio menu page offers the option of having the audio output, both headphone
and 5 pin either the default STEREO, or MIX. Because after many years of
listening to Sony camcorders only offering MIX in the phones I selected this
option to try it, and never switched it back. I know, it's a bonehead thing
to select, but I did. As soon as I switched the option back to the default
STEREO, all distortion has gone away. Summing the channels for the MIX
overloads the headphone amp. This can't be what Panasonic had in mind, but
I don't know why anyone needs the MIX mode anyway. I do however, think they
should be informed of this condition. Now I'm trying to get used to the
inherent delay in the audio path.
Jay Hartigan |
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External
Since: Apr 22, 2004
Posts: 328
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(Msg. 2) Posted: Wed Jan 28, 2004 10:03 pm
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> ...Summing the channels for the MIX
> overloads the headphone amp. This can't be what Panasonic had in mind...
If both channels are seeing the same input, summing them in the digital
domain results in a 6 dB boost.
(In theory it would also in the analog domain, but you'd need some buffer
resistors so each feed doesn't load the other down, and that would cause
some loss.)
(Dropping the digital signals -6 dB before summing doesn't require any
heavy-duty DSP; it's just a one-bit shift. Maybe they didn't realize it
was necessary.)
--
Correct address is spell out the letter j, AT dplaydahtcom
Clio- and Emmy-winning sound design
Learn audio for video at www.dplay.com |
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External
Since: Jan 11, 2004
Posts: 39
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(Msg. 3) Posted: Wed Jan 28, 2004 11:13 pm
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> This can't be what Panasonic had in mind, but
> I don't know why anyone needs the MIX mode anyway.
> Jay Hartigan
Jay, I've actually had to use the MIX mode for the 5 pin output on
that camera, as my clients needed to see/hear a LOT of playback, and I
had them all on comteks (for both EE audio during the take, and PB
audio during playback) at different video monitors. I was grateful
for the MIX mode, only because I didn't have another mixer or two
channel combiner to take both the left and right channels of the outs
into the single input of my comtek feed. The mono MIX gave me both
channels in my left or right, so I just had to run the one cable back
to my comtek for distribution in EE or PB.
-Jay Farrington
> Now I'm trying to get used to the inherent delay in the audio path.
> Jay Hartigan
Yeah, what's the solution to that, if any? I spent half the night in
the hotel room pouring over the manual after day one to see if there
was an "EE" selection for the headphone and 5 pin output. I found
nothing. I asked our local Panasonic rep about the delay, and he
scratched his head and said, "Really? Huh" and I never heard any more
about it.
My clients didn't seem to care about the delay during the takes, this
was mostly long lens stuff and they could only hear audio from my
comtek feed anyway, but it drove my poor boom op nuts, as she was
close to the actors. I had to keep us listening to the mixer most of
the time, instead of the return, which I don't really care to do when
the sound is going to the camera ONLY.
Has anyone figured this out yet, or is there no real solution?
-Jay Farrington >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Dec 14, 2003
Posts: 1680
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(Msg. 4) Posted: Thu Jan 29, 2004 12:39 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Jay Farrington" wrote in message
>
> My clients didn't seem to care about the delay during the takes, this
> was mostly long lens stuff and they could only hear audio from my
> comtek feed anyway, but it drove my poor boom op nuts, as she was
> close to the actors.
Why would you send a return feed to the boom op? >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Dec 26, 2003
Posts: 23
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(Msg. 5) Posted: Thu Jan 29, 2004 6:25 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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External
Since: Jan 11, 2004
Posts: 39
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(Msg. 6) Posted: Thu Jan 29, 2004 8:08 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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"Charles Tomaras" wrote in message
> Why would you send a return feed to the boom op?
Why do people eat Spam? Low budget. ;)
My boom op and I were sharing the same headphone output essentially,
as I was using a Cooper CS104. It also allowed me to talk to her in
the headsets from the slate mic. Not ideal, but I was lucky to even
get a boom op actually, so I was happy with the setup. And I prefer
to listen to the camera return when it's possible, but in this case,
it would be weird for the boom op who was sharing my headphone output
from the Cooper.
Mmmmmmm . . . Spammmmm
Jay Farrington >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Jan 11, 2004
Posts: 39
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(Msg. 7) Posted: Thu Jan 29, 2004 8:33 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> Have you heard any splashing of the peaks when using the MIX mode? I can
> see why MIX can be important.
> Jay H
I can't say that I did, but again, I ended up monitoring off the mixer
quite a lot on that dramatic shoot. I was mostly listening to the MIX
for playback, which is when you say you weren't hearing the problem,
so I'm not much help there, sorry. Subsequent shooting with that
camera has all been sit down interviews and pretty "unlively" dialogue
for me so far, so I haven't had many peaks to monitor honestly.
> Because of the digital processing of the picture with the 24P, the audio has
> to be delayed to keep it in sync with the picture. No way around it. > Jay H
And you say the delay problem is inherent with the 24P digital
processing? Riddle me this - why don't I hear a delay when monitoring
off a Sony F900? I've done more engineering with that camera than
sound, but I've done a fair amount of audio with Sony F900s at 24P and
I haven't noticed any slap-back delay like I do from the SDX-900 while
recording. I think the Sony has a true EE available during recording,
and the SDX-900 doesn't. Just a guess.
Have I always been that far back from the set that I haven't noticed a
delay on the return during recording on the F900? I don't think so?
Maybe. My guess is that the Panasonic SDX-900 just doesn't have an EE
selection the way other cameras do. Maybe the output is always from
the PB/confidence heads?
Anybody out there know the real answer to this? I think there's a
third Jay that may be able chime in here. Mr. Rose?
Jay Farrington >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Apr 22, 2004
Posts: 133
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(Msg. 8) Posted: Thu Jan 29, 2004 5:32 pm
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Okay, I may be talking through my hat, but one guess is that the Sony
may derive their E-E before the A-D and D-A cycle whereas the Panasonic
may derive E-E after A-D and then doing a D-A cycle. That might account
for a small time delay. I don't know this to be fact; I'm just guessing
here.
John Blankenship, Indianapolis
Jay Farrington wrote:
>>Have you heard any splashing of the peaks when using the MIX mode? I can
>>see why MIX can be important.
>>Jay H
>
>
> I can't say that I did, but again, I ended up monitoring off the mixer
> quite a lot on that dramatic shoot. I was mostly listening to the MIX
> for playback, which is when you say you weren't hearing the problem,
> so I'm not much help there, sorry. Subsequent shooting with that
> camera has all been sit down interviews and pretty "unlively" dialogue
> for me so far, so I haven't had many peaks to monitor honestly.
>
>
>>Because of the digital processing of the picture with the 24P, the audio has
>>to be delayed to keep it in sync with the picture. No way around it. > Jay H
>
>
> And you say the delay problem is inherent with the 24P digital
> processing? Riddle me this - why don't I hear a delay when monitoring
> off a Sony F900? I've done more engineering with that camera than
> sound, but I've done a fair amount of audio with Sony F900s at 24P and
> I haven't noticed any slap-back delay like I do from the SDX-900 while
> recording. I think the Sony has a true EE available during recording,
> and the SDX-900 doesn't. Just a guess.
>
> Have I always been that far back from the set that I haven't noticed a
> delay on the return during recording on the F900? I don't think so?
> Maybe. My guess is that the Panasonic SDX-900 just doesn't have an EE
> selection the way other cameras do. Maybe the output is always from
> the PB/confidence heads?
>
> Anybody out there know the real answer to this? I think there's a
> third Jay that may be able chime in here. Mr. Rose?
>
> Jay Farrington >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Jan 29, 2004
Posts: 3
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(Msg. 9) Posted: Thu Jan 29, 2004 5:32 pm
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Hi Jay F. and other posters,
It is interesting that the same manufacturer (Panasonic) produces
the DVX-100 camera, which shoots in 24P and does not have the same
delay problem while monitoring during recording. I know this camera is
a toy compared to the 900 camera but I'm sure that it is not an
impossible engineering feat to provide EE feedback from the 900. It is
very disorienting to listen to the delay and determine audio anomalies
which might be present. Is Panasonic trying to provide permanent
"audio confidence" with this feature?
Chris Coughlin, Marin CA >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Jan 11, 2004
Posts: 39
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(Msg. 10) Posted: Fri Jan 30, 2004 12:02 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> It is very disorienting to listen to the delay and determine audio anomalies
> which might be present. Is Panasonic trying to provide permanent
> "audio confidence" with this feature? > Chris Coughlin, Marin CA
Hey Chris,
Yeah, the "audio confidence" thing was my guess too, until I asked the
Panasonic rep directly about the delay and got the, "Really? Huh?"
line, and nothing further.
I think John may have the right idea about the SDX-900 just not
deriving the EE audio output/return until after the A-D and D-A
conversion cycle. It's as good a guess as any so far.
Anyone out there have "the answer" to this question? We're all
obviously making our best guesses only here.
Jay Farrington
Mmmmmm Spammmm >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Apr 22, 2004
Posts: 133
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(Msg. 11) Posted: Fri Jan 30, 2004 1:35 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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A sound mixer friend of mine has been doing some corporate type shoots
where they use the DVX-100s and he said that there is a very short time
delay on E-E. In late February, I have a shoot coming up using the
DVX-100, then I can see for myself.
John Blankenship, Indianapolis
See Sounds wrote:
> Hi Jay F. and other posters,
>
>
> It is interesting that the same manufacturer (Panasonic) produces
> the DVX-100 camera, which shoots in 24P and does not have the same
> delay problem while monitoring during recording. I know this camera is
> a toy compared to the 900 camera but I'm sure that it is not an
> impossible engineering feat to provide EE feedback from the 900. It is
> very disorienting to listen to the delay and determine audio anomalies
> which might be present. Is Panasonic trying to provide permanent
> "audio confidence" with this feature?
>
> Chris Coughlin, Marin CA >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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External
Since: Apr 22, 2004
Posts: 328
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(Msg. 12) Posted: Fri Jan 30, 2004 11:58 am
Post subject: Re: Distortion in audio monitor on Panasonic SDX-900 [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> It is interesting that the same manufacturer (Panasonic) produces
> the DVX-100 camera, which shoots in 24P and does not have the same
> delay problem while monitoring during recording...
Yeah, but that particular camera has a ~3 field offset between track and
pix on the tape. Yep: the tape itself is out of sync, because they don't
delay the audio to match the video chip scan and dsp delays.
--
Correct address is spell out the letter j, AT dplaydahtcom
Clio- and Emmy-winning sound design
Learn audio for video at www.dplay.com >> Stay informed about: Distortion in audio monitor on Panasonic SDX-900 |
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