[drop loud audio levels] Does the EX1 have a forced audio limiter in manual mode? at DVinfo.net

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Old March 16th, 2009, 09:10 AM   #1
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[high audio levels] Does the EX1 have a forced audio limiter in manual mode?

Hi there,

I filmed for several years with a Sony VX2100 PAL-SD-Camcorder (known as "queen of the night" because of its low-light-capabilities).

Two weeks ago I bought a brand new Sony EX1 (manufactured January 2009, firmware 1.11_531) to follow this camcorder. I film fireworks displays/pyrotechnics only - so I have some very special needs for those cameras.

Besides lowlight-excellence I do need full manual control on audio - without audio limiter. The explosions and breaks of large scale display fireworks are often very hard and furthermore there is often a music played from outdoor loudspeakers at musical fireworks displays.


Last weekend I did my first tries with the EX1. I filmed not with internal but with my old AudioTechnica 822 stereo microphone (1.5V battery power) with an Y-adapter cable XLR -> 2x XLR (left/right CH1/CH2). I used this micro successfully on VX2100 till now.

I am very sure that I used the correct settings, this means:

- choosing MIC (not LINE or +48V) at input connectors
- switching to MANUAL audio levels at camera's back
- switching to EXTERNAL at camera's back
- trying 4 to 5 as AUDIO LEVEL at wheels
- setting to -57db in MENU for EXT MIC SENSITIVITY
- using NO WIND FILTER

I of course set this always for both channels CH1 and CH2.


MY PROBLEM:
During smaller displays with some consumer fireworks or at display fireworks from a bigger distance (maybe more then 250-300m) everythings seems to be fine or better: its not possible to clearly notice the following problem - but it definetly can exist there too.

At larger displays in 150m distance, especially with music from loudspeakers one can clearly hear, that audio level dramatically drops immedietly (!) for a second after firing mortars from ground or breaks/explosions in the sky. Afterwards the sound rises immediatly back to normal level till next explosion.
This is what I normally would expect from an audio limiter at AGC-audio - but I definetly filmed in manual audio mode.

I further noticed that the 2 audio bars in display did not reach the right side, so they did not "tilt red" (peaking to 100% or more) as normally and as I would expect from that loud noises. I can "tilt red" when I rise sensitivity and audio levels and then clap with hands for testing.


I therefore do have some questions:

- does anybody have a similar experience (maybe not at fireworks, but with starting airplanes or other loud noises) -> is this "normal" for EX1? Does this machine have some kind of "audio protection" (= audio limiting circuit) for very loud levels, which cannot be disabled?

- can I reduce the effect when I set in menu sensitivity to maybe -11db and rise audio level on wheels to eg. 7 to 8 instead? Or do these 2 settings somehow "do the same level reduction"? I cannot go really lower in total, since I want to catch the music clearly.

- is it possible that this effect was not from the very beginning but did I maybe "crash" the EX1-audio-input after the first very heavy+loud shots? I would then expect somehow distorted audio but everything (music etc.) sounds very clean and fine between the explosions. Its just the 1-second dropping of audio-level after every bang.


Thank you for any hint - what did I wrong?
Regards,
Markus

P.s.: after searching this forums I did not really find an answer to my questions. If this has been discussed already please just give me an hint, what search phrases I should better use.
I just found this
http://www.dvinfo.net/conf/sony-xdca...n-limiter.html

Quote:
The EX1 _does_ have a limiter circuit in the audio chain, but it's not very good.

You can't enable or disable it, hence no mentions in the menus, it's just there.
If the last sentence is true I really, really have a problem with the EX1...

Last edited by Markus Klatt; March 16th, 2009 at 03:27 PM.
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Old March 16th, 2009, 09:50 AM   #2
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Yes, it seems there is a hard limiter in manual mode. The alternative would be peak distortion but on certain shots I'd rather the momentary distortion than the breathing the limiter causes. The only way to avoid is to set low enough so it doesn't hit the peaks.

BTW I've heard this when I've shot fireworks. I too wish there was a way to disable it.
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Old March 16th, 2009, 01:22 PM   #3
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Markus and Craig. During and after posting this thread:

http://www.dvinfo.net/conf/sony-xdca...reo-mixer.html

I did a lot of internet research on this problem. Let me summarize what I found:

You can't use most field mixers with the Line Input. The expected levels don't match. Use the Mic Input and set it to external. Then you have to watch out for your settings due to the limiters and adjust the Trim in the menu depending upon what you are recording.

Here are the most useful quotes I found regarding the External Mic input settings:

------------

One precaution users of the EX1 must be aware of is that there are non-defeatable limiters which are very crude in their ballistics and have nasty "ducking" effects when triggered in the slightest degree. It is imperative that one uses the attentuators to set the recording level, and NOT the record level dials on the outside of the camera. These should be set at "5", as this is the point where no further increase in recording level can be attained with a maximum level at the input before limiter threshold. Higher settings increase noise floor, lower settings will attain clipping at less than digital FS.
Be familiar with the expected SPLs when you are recording. To avoid limiter artifacts, no peaks should ever exceed the 4th white segment before the red segment on the EX1's on-screen meters. I generally record concerts and pyrotechnic events and set attenuators so that average level is about mid-scale on the meters--that way the peaks are well under the limiter's trigger point.

BassPig


http://www.vimeo.com/1408795

---------------
also:
---------------
There evidently are TWO limiters in the EX1: One appears just downstream of the attenuators; the other downstream of the record level controls.
This can be observed by feeding signal to the camera’s input jacks at gradually-increasing levels, while the record levels are set to 5. At some point, the sound will start to take on a “broadcast on the radio” quality, as the dynamics will be flattened out. Turning down the record level won’t change this compression effect, though it will reduce the record level going on to the SxS card.
The only way to remove the effects of the input limiter is to increase the amount of input attenuation. The smaller the number, the greater the attenuation. The numbers refer to the signal level that is needed to be present to achieve a reference recording level. Since they are negative numbers, smaller is bigger. By increasing the attenuator setting (so it is less sensitive) the signal peaks will be reduced below the limiter threshold and the sound will pass pretty much un-altered.
Even if you set the attenuation correctly, you can still hit a secondary limiter if your record level is too high. I find that a setting of 5 is optimal. Any higher than 6 and there will be an increase in the noise floor. If you need more gain to record quiet content, like nature sounds, it is more effective to reduce input attenuation than to turn up the record gain.
An observation about the Auto gain control setting: it completely ignores your input attenuator settings. The camera will not be able to handle high SPL situations in Auto. Use Manual gain and set levels conservatively. You can always normalize in post, but you can’t fix badly-compressed and clipped audio in post.
In conclusion, if you want to get the most out of the audio system on the EX1, you must set both the attenuators AND the record gain appropriately for the situation.
Here are my suggestions, vis-à-vis the Rode NT4 (dB SPL levels are peak, not average):

Quiet nature scenes, SPLs under 70dB. Set attenuator for -38dB (good to 106dB)
Small acoustic or singing ensembles. Set attenuator for -32 or -29dB (good to 115dB)
Jazz ensembles with moderate amplification. Set for -23 or -20dB (good to 124dB)
Loud disco or rock band concerts. Set for -14 or -11dB (good to 133dB SPL)
Fireworks should use the -14dB range, if you’re close enough to need earplugs.

Record level of 5 will pretty much provide full-scale (full scale without limiting is 3 dots short of the red dot on the EX1’s audio level meter scale). A level of 6 will push things toward more limiting on the secondary limiter stage and a little more hiss from the preamp. 5 is really pretty optimal, with adjustments to attenuators for expected maximum SPL.
With careful adjustment for the given situation, the EX1 can provide near-audiophile-quality recordings of musical, pyrotechnic and natural sound events without the need for separate audio recording methods.

Mark & Mary Ann Weiss


http://dvxuser.com/V6/showthread.php?t=132249

--------------

I am sure that more is to come down the road, but that seems like a good basis to start with.

John

Last edited by John Peterson; March 16th, 2009 at 04:00 PM.
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Old March 16th, 2009, 02:46 PM   #4
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Thank you both for your input and special thanks to John for the specific help!

Now I know:

- there is/there are limiters which cannot be disabled
- I did not crash the camera's audio inputs with the first heavy explosions - there is no chance to do so because of the limiters ;)
- maybe there is a way to solve the problems without external audio recording

Since English is not my native language I am not sure if I've fully understood the quoted text:

- "5" as audio levels on the "wheels" is near optimum. Higher values will result in audio noise and clipping. Will 4 do less clipping then? When I check my fireworks footage from the weekend I could believe that "4" cuts more explosions then "5". But maybe this is just because of different sound levels of the different display parts.

- setting -57db for the sensitivity for a fireworks display as I did is much to much. I will try starting from -23 to -20db for musical displays and maybe go towards -14db for hard breaking displays in Southern European style without musics.


So, after your comments I believe one can find good settings for pure fireworks displays. But I am not that sure if those settings will fit my needs for displays with loud explosions but normal to silent musical parts at the same time...

Thank you so much for the moment and any more comment is highly appreciated!
In any case I will tell you my findings after filming next displays (I am not sure when this will be, latest in April)...

Best regards
Markus
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Old March 16th, 2009, 02:51 PM   #5
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Quote:
Originally Posted by John Peterson View Post
I am sure that more is to come down the road, but that seems like a good basis to start with.

John, "thank you" for sharing your research and insights into the EX audio system. This is a good practical explanation that finally begins to shed some light on the subject.

While I have had success recording with a monaural Shennheiser microphone using the menu attenuators, stereo recording with my Audio-Technica has been extremely difficult to get right. Two limiters in the recording chain for each channel, puts EX audio setup into a whole new perspective.

Sony is dreadfully remise and needs to issue a technical bulletin and/or an addendum to the EX manuals.
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Old March 16th, 2009, 03:02 PM   #6
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Quote:
Originally Posted by John Peterson View Post
[i]There evidently are TWO limiters in the EX1: One appears just downstream of the attenuators; the other downstream of the record level controls.
This can be observed by feeding signal to the camera’s input jacks at gradually-increasing levels, while the record levels are set to 5. At some point, the sound will start to take on a “broadcast on the radio” quality, as the dynamics will be flattened out. Turning down the record level won’t change this compression effect, though it will reduce the record level going on to the SxS card.
John
Isn't this just the input amplifiers and A/D's being over-driven. You would expect this behavior with many digital recording devices.
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Old March 16th, 2009, 03:02 PM   #7
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Input attenuation levels can vary depending upon the types of mics you use. Some are "hotter" than others and require more attenuation. So the information above should be considered as a set of guidelines than specific settings.
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Old March 16th, 2009, 03:36 PM   #8
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John,

With all due respect, I believe that quoting somebody else's text literally and at such an extent, you should have mentioned its author (Basspig), and give him some credits :)

Even if for some reason or another, he once was made to stop posting in this forum...
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Old March 16th, 2009, 03:45 PM   #9
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Originally Posted by Piotr Wozniacki View Post
John,

With all due respect, I believe that quoting somebody else's text literally and at such an extent, you should have mentioned its author (Basspig), and give him some credits :)

Even if for some reason or another, he once was made to stop posting in this forum...
You are right Piotr. I'll fix it now. Actually it was two different posts by two different people. I wasn't thinking.

John
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Old March 16th, 2009, 04:03 PM   #10
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Originally Posted by John Peterson View Post
You are right Piotr. I'll fix it now. Actually it was two different posts by two different people. I wasn't thinking.

John
Glad you got me right, John - and I hope you don't mind :)

BTW, "Basspig" and "Mark & Mary Ann Weiss" is the same user, a true expert in audio.
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Old March 16th, 2009, 04:14 PM   #11
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Quote:
Originally Posted by Piotr Wozniacki View Post
Glad you got me right, John - and I hope you don't mind :)

BTW, "Basspig" and "Mark & Mary Ann Weiss" is the same user, a true expert in audio.
Really? Maybe that is why the two posts agreed so much. I'll have to look at their website and bio. That information helped me a lot, that's for sure. That's why I posted it here. We need to get to the bottom of getting the most out of the audio on this camera.

John
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Old March 16th, 2009, 05:09 PM   #12
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Quote:
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That's why I posted it here. We need to get to the bottom of getting the most out of the audio on this camera.
John

Agreed, that is why a synthesis is much more useful than the parts. This challenges us to grow in the understanding of our craft by consistently acquiring good audio to accompany the EX video. Cheers!
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Old March 17th, 2009, 02:03 PM   #13
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Thanks for all the input! But one thing is still not clear for me:

I set audio level to 5 and 4 (changed between shots), external attentuators were set to -57db, no wind filter.

With this combination the explosions were massivly hearable in the recorded clips (besides the cutting of the loudest parts and the drop of the music as mentioned), but the audio level bars did never reach the right side (peaking to 100%).

So, the EX1 cuts before the noise "reaches the audio bars" and they only show the resulting (cut/lowered) levels?!
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Old March 17th, 2009, 06:04 PM   #14
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I don't have to the post to hand, but Basspig recently updated his firmware, and noted the limiter function had greatly improved. He seemed pretty impressed.
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Old March 18th, 2009, 01:29 AM   #15
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Have you tried a Dynamic microphne. I believe that they are the best for inside helicopters, kanons and explotions. I cannot say if it will help but you will not have an amplifier in the microphone and it will probably not deliver a high enough output, to give the camera any problems.

Last edited by Bo Skelmose; March 18th, 2009 at 08:11 AM.
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