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Old February 18th, 2008, 02:16 AM   #1
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Quality of EX1' mic-preamp?

I don't intend to use an external audio mixer - so how good is the EX1' mic-preamp? Can anyone share audio files for demonstration?
Thanks in advance.

Background: I was very pleased with the audio qualities of the FX1. Now I am a little worried about the audio capabilities of the EX1 since Sony forgot to implement a limiter.
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Old February 21st, 2008, 05:12 AM   #2
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While the sound quality can really be great on the EX1 (at least compared to what I got with my V1E), I have recently noticed very nasty artefacts when using external mic with attenuation set to -56dB in the menu. It resembles the wind rumble, only... there was no wind! Please listen to the attached wav file and tell me: is it the clipping due to the lack of a soft limiter (yeah, I know it's too hot - but the point is I have no idea what is making that noise; when I switch to the internal mic, the sound is a bit lower and there are NO cracks like this):
Attached Files
File Type: wav clipping.wav (1.05 MB, 223 views)
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Old February 21st, 2008, 05:20 AM   #3
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Piotr, did you use a phantom powered external mic?
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Old February 21st, 2008, 05:34 AM   #4
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Yes, Michael - it's the Edirol CS-50 stereo shotgun. It worked great with my V1E (much more sensitive than the poor little shotgun the V1 comes with). Sometimes I did get the wind rumble, but only when it was really windy; also it was much lower frequency. I never used this mic with another camera, so now when I'm getting cracks like this with the EX1, I have no idea what the reason is, as I have nothing to compare it with.. Is it a typical clipping noise? I'm afraid that if I set the attenuation to the default -41dB, it will simply be lower, but still there...
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Old February 21st, 2008, 06:25 AM   #5
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It's certainly not clipped, peaks at -6dB.
Spectrum analysis shows energy all the way down to below 10Hz.
Pretty certain it's wind noise. Some mics are very sensitive all the way down, you need to protect them from any air movement, moving air is sound.
You probably didn't hear this before because of the LF roll off in the V1 that you complained about.

Just to make certain put the mic inside an enclosure that is fairly air tight, just dont let it touch the sides.

It might sound like clipping if your monitors can't handle that much energy at low frequencies.
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Old February 21st, 2008, 06:43 AM   #6
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Quote:
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You probably didn't hear this before because of the LF roll off in the V1 that you complained about.
Thanks Bob, you're the best!

I certainly have been at lost... Peaks high, but not _TOO_ high - it didn't seem like clipping to me, either. On the other hand, it really wasn't _THAT_ windy when I recorded - for sure on the V1E, the same mic wouldn't generate the typical wind rumble in similar conditions. And yet, when shooting now indoors with the EX1, this doesn't occur!

So - with your diagnosis - it seems the EX1 is _REALLY_ much better in the bass department than the V1 - which is good news. Wind, I can take care of...
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Old February 21st, 2008, 08:13 AM   #7
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OK - just an update: switched wind noise protection on in the menu, and the crackings are gone. Sounds obvious, but with the wind we're having now, I wouldn't have to do it with the V1E: its bass response is really poor, compared to the EX1!

EDIT:

And yet, I do have some doubts... It's not completely gone, and when it occures, it's strangely most pronounced in higher frequency range that all wind noise I ever witnessed on other cameras, thus being more difficult to filter out using the simple roll-of around 60 Hz or so.

Anyone has similar experience with wind noise on the EX1?
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Last edited by Piotr Wozniacki; February 22nd, 2008 at 03:52 AM.
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Old February 23rd, 2008, 05:06 AM   #8
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Sorry for bumping this up, but I nead some more feedback on that. I mean, I jumped on Bob's suggestion as it not only explained the distorsion as not being related to the lack of a soft limiter, but also implied indirectly the EX1 sound section is so much better in the bass department than that of the V1...

However, even with a dead-cat on, the Edirol's own bass roll-off at 60 Hz, and the camera's wind noise suppression on - I still cannot get usable audio outdoors with ever so slight wind... I'd gladly accept the explanation that it's due to the better bass response this camera has when compared to the V1 (which I didn't have any wind problems with the same mic, except for really strong winds), but I have serious doubts because the noise is not most pronouced in the lowest frequencies at all using my THX-certified 5.1 speakers with very efficient subwoofer! Even though the frequency analysis in Audition confirms what Bob said about the most of the energy being all the way down to the bass area, I can actually hear distorsions much higher as well (I guess around 1-2kHz). Therefore, with all the classic wind-protection measures mentioned above, even using the equalizer to considerably lower anything below 100 Hz in Vegas doesn't help!

What else can be done to enable using this mic outdoors? With the V1E, it was great for recording nice ambient sound when set to WIDE; now the sound is unusable with even the slightest air movement.
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Old February 23rd, 2008, 05:59 AM   #9
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You could try something like the DPA Windpac but they're pretty expensive.
If you've got the microphone on the camera then you're going nowhere. As air moves over an object turbulance is created and that makes sound which the microphone will pickup. On a camera with many sharp edges the mic is simply recording what it hears.

Bottom line is, if you're remotely serious about audio you must get the mic off the camera. Not only is it in the wrong place for hearing what it should, it's in the wrong place for hearing what it shouldn't.
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Old February 23rd, 2008, 06:05 AM   #10
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Quote:
Originally Posted by Bob Grant View Post
Bottom line is, if you're remotely serious about audio you must get the mic off the camera. Not only is it in the wrong place for hearing what it should, it's in the wrong place for hearing what it shouldn't.
Absolutely right Bob - for serious sound recording (like live music), I already have the mic stand, set of good cables, etc.

But for casual recordings of ambience, why was the on-camera placement OK on the V1, and not on the EX1? What I am afraid is that what can be heard in the sample I posted earlier, is actually BOTH the wind noise (in lower freq range), AND some clipping distorsions (heard around 1-2 kHz).
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Old February 23rd, 2008, 07:38 AM   #11
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Quote:
Originally Posted by Piotr Wozniacki View Post
Absolutely right Bob - for serious sound recording (like live music), I already have the mic stand, set of good cables, etc.

But for casual recordings of ambience, why was the on-camera placement OK on the V1, and not on the EX1? What I am afraid is that what can be heard in the sample I posted earlier, is actually BOTH the wind noise (in lower freq range), AND some clipping distorsions (heard around 1-2 kHz).
The sample you posted earlier had no clipping. Clipping is pretty easy to see, look at the highest / lowest peaks. If they've got flat tops / bottoms, then you have clipping. It is possible to get analogue clipping / overload if your gain staging is messed up, then the peaks might be a bit more rounded when they get clipped than pure digital clipping but either way it's pretty easy to pick visually looking at the waveforms.

Now what you might be hearing are sample rate errors. These sounds like very sharp clicks. There's some posts around regarding the EX1 that seem to indicate to me that something like this is going on. Clips sound just fine in the clip browser but not after export. Try listening to the clips direct from or in the camera and compare how they sound after you export them to .mxf and open them in Vegas. I certainly didn't hear any such things in the clip you posted and I'm pretty conscious of them, one client has them real bad an intro he likes to use. The click removal tool in SF used for vinyl restoration can get rid of them but they shouldn't be there in the first place, assuming that's what you're hearing.

Ignore all of that, I just had another listen.

I'll post something in a few minutes.
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Old February 23rd, 2008, 07:56 AM   #12
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Looks like sample rate errors!

Take a look at the image I've attached.
At a rough guess what I've highlighted on the waveform from the file you first posted is the cause of your problem. It's hard to say for certain what the problem is but my best guess is sample rate errors. Whatever those nasty sawtooth things are I'd wager good money they shouldn't be there.

What were you recording in?

I've been sticking to 50i and not noticed a problem but if I can find the time I'll do some more tests. Maybe you can try shooting 50i and see if the problem goes away.

You still should get the mic off the camera though :)
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Quality of EX1' mic-preamp?-sample-rate-errors-highlighted.jpg  
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Old February 23rd, 2008, 08:59 AM   #13
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Bob, I was recording in HQ 1080/25p (as most of the time). I will certainly try other formats, but:

- from what people are posting about the clicks in Vegas, I understand it happens without relation to the wind noise; I'm NOT getting these without wind (like indoors for example)

- even with some wind, when I switch to internal mic, there is no clicks either (just the usual low freq rumbling when the wind is really noticeable).
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Old February 23rd, 2008, 09:47 AM   #14
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I got the Sony ECM 680S (did you know Sony is also offering rebates on mics and monitors with the EX1 purchase?).

I was shooting a 2 person "chamber ensemble" in a small Cafe and found the EX1 Mic sensitivity CRITICAL to getting good sound from the shotgun. I noticed what sounding something like wind noise when I first started shooting even though I was in a very quiet Cafe (no air conditioning, fans or "kitchen" electronics where I was shooting). Adjusting the sensitivity fixed it.

The noise was not coming from the acoustic space as far as I could tell. It's as if the camera pre amp was amplifying low level electronic noise in the signal path.

I was listening with Sony 7506 headphones.
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Old February 23rd, 2008, 04:05 PM   #15
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Piotr:
My sample rate theory does have some holes in it. It doesn't looks like what I'd expect (abrupt jumps in the waveform) and it would be noticeable regardless of content and microphone.
It's quite likely something else and I'm really taking stabs in the dark as I don't have the same mic to try it out first hand and don't really have much information at hand. I can only add the following.

There's only two things that I know of that affect how a mic performs in relation to what it's connected to. Quality of the phantom power supply and load impedance. The latter seems to really only have a major impact on dynamic mics apart from gross mismatches and shouldn't cause what I've seen on those waveforms. Noise on the phantom power supply could be the culprit, different mics have better filtering so results will vary depending on the mic. However I'm not seeing anything odd in the quieter sections of the sample, it could just be the phantom supply running out of power at such low frequencies.
Given that you're saying you don't have the problem indoors I have to discount what Craig is hearing as relating to your problem. At the same time we don't know how your camera is setup. Are you using AGC, what is the mic gain set to in the menu, how sensitive is the mic overall. There's nothing else in the sample to give any indication of the relative level of the wind noise in the first place. I'd even try taking the mic off the camera outdoors and see if that makes a difference, could be induced electrical noise. Does the annoying clicks relate to the operation of focus, zoom or iris servos. You need to do lots of controlled tests before reaching any conclusions. Trying to resolve an issue from what you've shot isn't a good way to resolve the problem. You need to devote time to working through all the variables, changing just one at a time in the different environments.
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