EX3 Audio Question
 

As I've said before, the manual--Operating Instructions--for the EX3 leaves a great deal to be desired.

For instance, under the AUDIO SET Menu, can some tell me where I can find more useful information on the "Trim" and the "Wind Filter" settings?

Thanks!

On the EX1 :The trim audio functions are available(accessible) only on external mics.

I agree with Jay.

Can someone please explain in more detail what Trim is all about? What does it actually do and what does one achieve when the settings are altered?

Thanks, Bob, I was able to figure out that much on my own. I've also figured out that the higher (lower since it's a minus?) the number is the louder the sound becomes.

I want to know:

1. What it is.
2. How it works.
3. It's strengths & weaknesses
4. How best to apply it.

Those are great questions, Jay, and they're right up our alley. I'm looking forward to watching this thread develop into some solid, usable information about EX series audio.

I'm very interested in this as well. I don't want to have to fall back on auto level control, but I feel like I'm working a little blind going manual.

I use both Sennheiser wireless going line in and an NCG-1 Rode using Mic+48. How will trim affect these?

The level controls are fairly straightforward - my understanding is that I need to prevent clipping and peak somewhere around -12dB for normal audio The occasional loud noise should never exceed 0 or I've lost it. But this doesn't help me any when it comes to the trims.

Also, in the same menu, I've heard people praise the wind filter. More feedback on this would be nice, too. Should it only be used outdoors? Should it never be used and should this be handled only by your 'softie' or in post if necessary?

Ted, the Wind Filters only work with the internal/onboard mic. It has no effect on external mics.

So far, I've figured out that the larger the minus numbers are in the Trim setting the more volume you get for the external mics. Currently, I have both channels set at -54dBu. This seems to work with my Rode NTG-3.

Not being a high-tech audio person, I really anxious to figure this out before I create a problem.

I don't have my EX1 with me (gone for an overhaul), but I don't think that's right - please correct me.

Regarding the trimming: due to the internal limiter (yes - there IS one) weirdness, it's always safe to have it quite aggressive (like around -30dB), and the gain at the neutral position (i.e. 5). Should a sudden loud audio event occur, this will prevent from anti-clipping compression which can sound really ugly.

The overall quality of the EX audio is good enough to increase the (perhaps too low) overall sound level in post, without introducing hiss or other noise.

Piotr, according to Doug Jensen's "Mastering the Sony PMW-EX3," the Wind Filter works only with the internal mic. Take that with a grain of salt.

The trim function adjusts the sensitivity of the input. Different microphones and audio devices output at different levels. For example a radio mic receiver that outputs at mic level will probably be "louder" than a dynamic type microphone. The trim adjustment allows you to compensate for these varying levels. -67dBu is more sensitive than -11dBu.

I set the trim by first selecting manual audio level control. Turn the level control knob to the mid position (5). Talk in to the microphone at the level you expect for the job and look at the audio levels. You want to have the levels in the "comfort zone", ie mid range, not too high not too low. Certainly not going past 3/4 of the way up the scale, hopefully peaking just a little past half way. Use the input trim if your levels are not in the comfort zone.

If you make the microphone too sensitive (say -67dBu) and then have to wind the level control down to get a decent level your recordings may be noisier than they would be with a less sensitive setting, also it is difficult to make small adjustments to the recorded level if you have the knob turn all the way down. Also loud noises may overload the input and cause distortion.
If you don't make the input sensitive enough then you may struggle to record good audio levels. When you go to edit your material you then might have to use a lot of gain in post production to bring the audio up to the correct level. This will introduce noise and in effect reduce the dynamic range.

If anything it is better to be a little on the low side when it comes to levels. Too high and you will get distortion, unexpected loud sounds may clip, whereas if you are a little low a small amount of tweaking in post shouldn't hurt too much.

For my condenser type gun mics I am normally somewhere around -47dBu.

The wind filter is a simple low cut filter that cuts off some of the low frequency rumble caused by wind blowing across the mic. It works on both the internal and external mic.

The EX cameras have an aggressive audio compressor that starts to kick in before the levels get in to the red. The limiter has a fast attack and delay. If your audio levels are set too high you can hear the audio pumping. Often most evident if you turn the volume up and listen to the background noise which you will hear going up and down in volume. To avoid this keep your audio peaks to around the 3/4 mark and no more.

This is how I do it and it works for me, others may have a different view.

Thank you, Alister, that was a big help! You've provided enough information that I can begin to see what the Trim is and how it works.

Any further insights by anyone else would be greatly appreciated.

Alister - Thanks so much! I've finally had my EX3 audio primer!

Thanks Alister from me as well.

However I would like to ask whether the "trim" function works in the AGC mode for audio. My work is primarily run gun type and there is no time for manual control of audio. If the trim level is altered in auto level audio what would be the effect?

I think Alister has given some good advice. My reading of the trim settings are a little more technical. Most mic level signals should correspond to a -60db to -40db range. Consumer line levels (usually RCA) range from -20DB to -10DB. Professional Line Level ranges from 0DB to +4DB. The trim should be used to try and match the mic output to the camera input so you get a proper audio recording without distortion from impedance mismatches. It is very possible to set the trim characteristics incorrectly and have distortion added to the signal recorded by the camera even if using auto level record settings. Some Radio mics have adjustable outputs and this should be considered when setting up the inputs for the EX1. Many mixers have adjustable outputs (ie Sound Devices) but many don't so tests should be done to see that the inputs can handle the level coming from the external device. Defnitely not as easy as just a good old Mic Line switch which was usually mic at -60 and line at +4

Thanks for your input, Daniel. I have a couple of questions:

How does one match the trim with the mic's output/impedance? For instance, my Rode NTG-3 has an output impedance of 25Ω.

How does one avoid this?

Jay,
I hate to say trial and error but this is basically what happens using Alister's procedure as a starting point. Most of the inputs on Sony machines use a much higher impedance so it is not just a question of matching up the impedance number.
The idea is to see if you are getting too much or too little output from the device you are sending to the camera. Don't just rely on Tone for this as it is easy to adjust tone to some level and not hear distortion from regular audio like voice and music. Try different dynamic sounds to see if the circuitry adds pops or clips or other noise without the level overmodulating.(Ie the phrase Testing 1 2 3) If the level is within range and the sound doesn't sound clean then you might be in an instance when the trim is coming into play. Listening to the headphone outputs of the camera or playing back tests is the best way to see if the mic and camera are getting a long.

The best way to avoid having distortion from a source while using auto is to set the source up in manual before giving the auto function the job. Try and remember what trim settings work well with each piece of gear and check them before recording.

If I may I'd like to add that I really recomend updating to ver 1.11 firmware to get better audio. Before I did this I had big problems avoiding distorsion and clicks when the wind blew or other sounds peeked. It was really hard to find the right sensitivity level.
After upgrading the the camera is much more tolerant to wider dynamics.

Yes, Ola, that would help with the EX1. However, with the EX3 the firmware upgrade is not necessary.

In a nutshell, if I understand all this correctly, and there is the excellent chance that I do not, you set the camera’s Audio Level controls (which some are calling “audio gain”) for channels 1 & 2 at “5”. Then you go into the Audio Set menu, under Audio Input, and set the Trim CH-1 and Trim CH-2 (which are calling “attenuator settings”) based on your mic’s sensitivity—this is merely a starting point. These settings are then adjusted based upon what you’re recording. Isn't that what the Audio Level controls are for?

Actually, this approach seems a bit bass-ackward to me. In a studio situation, this works just fine, but in a run-and-gun documentary environment this would be close to impossible to use.

Also, it would be an ENORMOUS help if everyone used the same nomenclature, based on the piece of equipment being discussed.

Another thing, unfortunate as it is, we are not all at the same level of understanding in all things. When those who are expert in any given subject write as though their readers have the same level of understanding they do, their explanations are of little value.

Am I too far off base here?

It's awkward, and that's why I recommend a very conservative approach - setting the trimming to an aggressive -30 dB (or so), keeping the output level knobs at the neutral 5. When it's too low (watching the meters), and you're absolutely sure no loud event can happen suddenly, you _might_ rise it to some 7-8 with the knobs, but you don't have to - because, as I said before, the S/N is high enough in this camera to safely rise the sound level to your liking in post, without introducing any hiss.

This way you are protected against sudden events (strong wind guts, or somebody firing his shotgun at you :)), which - with less relaxed trimming like in the [-40, -58] dB range - might trigger the limiter, which, acting as it does, can lead to compression distortion (pumping, and clicking noise).

Piotr, your comments are very interesting.

I'm encountering a problem in weddings during the cutting of the cake - there are usually a number of poppers going off. These produce a sharp but high volume sound (like a muffled gun shot). The audio always pumps following such poppers leading to a horrendous sound.

My settings are: auto audio levels (I cannot work manual here as I have no time to control the levels) and a trim level of -41 dB (both on the internal mic and on the external mic). The external mic is a Sony short shotgun type.

So, if I understood you right, if I choose a trim level such as -58 or -74dB would I eliminate such problem or is it due to the fact that I'm keeping the audio levels on automatic?

No, No , and once more - No !

Avoid auto setting like a plague - your pumping is caused by using it.

And remember about the "reversed scale" of trimming: your suggested -58 or -74 dB is actually far more relaxed trimming than what I'd recommend (of course, exact values depend on your mic sensitivity, and the actual "sound stage"). It works the other work round: lower (absolute) number gives more aggressive trimming, so -30dB is "more trimmed" than - 58dB.

I mainly record live music events, where the only outburst in the sound level is typically the audience applause - and yet I never trim my mic above (or below, is you consider it's in the minus domain) some -38 dB.

For events like yours (weddings, fireworks, etc) I'd even go higher (OK -lower, if you follow me), to some - (20-30) dB.

So, too avoid pumping and "clicking":

- no Auto!!!!
- aggressive trimming (around -30 dB); you can safely rise the sound level in post

I hope I was clear enough - forgive me if not, I'm really tired right now :)

Piotr

Brian, the higher the minus number is (-58 vs. -30) the more volume (louder) you get (don't ask me why). So I would think you want to do in the opposite direction.

Try it out. You'll see what I mean.

Wind Filter Info Correction!
 

Ted, I owe you an apology. It appears that I was mistaken in the above statement.

Today I got a Rycote Softie (aka deadcat) for my NTG-3. Miami, being on the coast, is always windy. Even with the Softie, I noticed considerable wind noice. Just for the heck of it, I switched on the Wind Filters. By golly, they worked!

If the mic were in a blimp with a deadcat and the WF applied, it would be dang near perfect.

My apologies to all for the misinformation!

No problem, Jay.

Regarding the Trims, think in terms of what level you are allowing them to trim to. If you are limiting their trim down at -54 or -78, you are hardly letting them trim at all. If you allow them to trim up to -30, then it is trimming more agressively and that is why it sounds quiter.

Now, you wouldn't have to manually adjust these doing run n gun except in the most extreme situations, perhaps. What you are adjusting for is the mic that you use. So, the reason that you start with gain at 5 is to give you the most flexibility after you've calibrated your camera to your mic.

Once the Trims are set according to your mics, then you have your gain control available to tweak for the situation. Just keep peaking low - no more than 2/3 of the scale. Then, if the odd loud noise happens, it hopefully won't clip. When the audio is too soft, then you bring it up in post.

Because you have calibrated the trim for your mics, and recording levels of the gain control aren't cranked, and because the audio system of the camera is good, you'll have a low signal to noise ratio and therefore the ability to bring it back up in post without hearing a lot of noise.

Thanks for the further explanation, Piotr. I've read your last post several times, and it's beginning to sink in now.

Ted, thanks for your explanation, too. That was a great help!

I guess that's what's confusing me--calibrating a microphone. I can calibrate a monitor because a "standard" is provided. I can calibrate the white balance because a "standard" is provided. I can calibrate exposure because a "standard" has been provided.

Is there a "standard" tone somewhere, for example, provided for calibrating mics?

Tone won't work, as it is internal. You are adjusting for the the mic and the environment simultaneously. Perhaps "calibrate" is to optimistic a term - maybe "adjust" is all you can hope for.

With the gain at 5, Allister recommended speaking into the mic. The idea here is to approximate the situation you expect to be in and adjusting the trim accordingly. You can still adjust gain as necessary for the situation. Just keep peaking from getting to close to the top of the scale.

Jay, please take this with a grain of salt. I'm learning right along with you and this is all based on a little bit of background in audio, Allister's recommendations for this camera and my testing. Tomorrow, we might all say, "No, six is where the gain should be when you adjust - whoever heard of five?"

Okay, I'm with you, Ted. The trims aren't a magic bullet. They're just trying to get you within the ball park, whatever it may be. Sound still is what it always has been. I can deal with that.

So, excuse me if I'm going to ask a stupid question - but does this mean that even in run n gun situations one should NOT use automatic levels?

So if I have understood right Piotr and the others are saying that ideally one should:

1)set audio on manual control

2)start by setting the audio levels on 5

3)trim at a level of about -30dB


These settings should give a relatively safe starting point and should the levels start getting too close for comfort one can adjust the audio levels?

Or have I understood the whole procedure wrongly?

Audio is not my strong part.........clearer explanation would be most welcomed!

Yes Brian - you got it right :)

That's right, Brian. Using the auto levels will cause more problems than they solve. It does to the sound what auto exposure does to the picture.

Alistair's explanation is a fabulous starting point and covers most of the essentials particular to HOW to use the trim control to pad a signal presented to the microphone input on your camera. But there's a little more as to the WHY this is so critical.

Essentially, you want the signal hitting the input stage at the camera to be optimal. If it is, you shouldn't have to mess with the TRIM control at all since I'd assume the one on the EX-1 is a PASSIVE pad - suitable for lowering the signal without any capacity for actively boosting a weak signal. (Trim controls on active devices like desktop audio mixers often allow both cut and boost)

The critical factor is that strong peaks presented to any digital audio recording system are CATASTROPHIC if they result in a too hot signal entering a digital recording stage. You go from clear audio to unlistenable GARBAGE in a millisecond.

So a trim control present at the point of audio input at your camera is the FINAL line of defense between you and audio disaster.

If you'd like to learn more. Do a web search on the term "gain structure." This is the term audio engineers used to describe balancing all the inputs and output levels in a recording chain so that when the signal gets to the point you're going to record it, you've maximized the useful information in the signal WITHOUT overdriving or underdriving any particular stage and therefore adding either noise or distortion into your audio signals.

The traditional way to set gain structure allows you to use your on camera recording controls to make SAFE adjustments to your audio levels without the need to worry that you can turn things up TOO FAR and therefore spoil your recording.

In a concert or commercial recording setting, it's typical for the house to send out a 0db tone at 1Khz that you can use as a reliable baseline to set the gain structure of your camera.

WIth that, the typical procedure is to START with your on-camera audio level inputs at 80-90% of it's FULL ON setting, then use the TRIM control to set a level with enough headroom to make sure that if something BUMPS your audio control to full, you STILL have a safe level.

One sure sign of a BAD gain structure is if you're running your camera audio controls TOO LOW as a way to compensate for a hot input level. It's dangerous because if something bumps your input setting, bad things can happen fast.

Learning to consider an appropriate gain structure EVERY TIME you record sound is something on par with taking a white balance when light conditions change. Time spent working with your microphone(s), your wireless transmitters and receivers or whatever else is typically feeding you sound - and knowing how they affect your gain structure right up to the input of your camera is critical if you want to maximize your audio quality. Do that and you should rarely have to mess with the trim controls - and only when you've got not time to mess with things and someone sends you a too hot signal you aren't expecting.

Hope that helps.

Thank you, Brian, for that detailed explanation.

I did a search, as you suggested, for "gain control." Again, the information provided is written by one who knows the technology for those who know and understand what the author is talking about. That leaves the rest of us out in the cold.

For instance, Sony didn't say in the manual (EX3) that the camera has Interval Recording and leave it at that. They provided detailed information (on page 74) explaining how to set up the Interval Recording capability. They should have provided similar information on how to set the Trim control.

They did, Jay. I own the EX1 but I downloaded the EX3 manual (.pdf) and it is explained VERY briefly on Page 68 under the heading "To Adjust the Levels Manually". As others explained, you are using the initial menu-driven level controls to compensate for the different efficiencies of different brands and types of mics. If I'm standing in front of the same sound source, my condenser shotgun has a different output level than one of my handheld dynamic mics. Once I compensate for the difference between different mics (with my external faders controls set to "5"), I can then make minute adjustments once I'm rolling. And, according to the EX3 manual, this external fader can either boost your signal by +12dB (when set to "10") or cut the audio to completely off (when set to "0"). Hope that helps.

Sorry, Dave, but you're mistaken. On page 68 of the manual that came with the EX3, there is nothing there as you described. And so far as the PDF copy is concerned, there's nothing on page 68 there pertaining to the use of the Trim settings, either. The below image is a screen shot taken directly from the PDF of the EX 3 Owners Manual, page 68:

Okay, then I must be confused as to what the question was. Can you restate it or clarify?

I'm not sure if you're responding to Brian, or me, Bill - but regardless, if you actually searched on "gain control" you're looking at a topic that's NOT the same as what I suggested which is "gain structure."

Precise terminology in this stuff matters - often quite a lot.

"gain control" would be expected to deal with controlling the amplitude of a specific audio signal hitting a specific circuit. The other - "gain structure" - deals with the process of setting appropriate gain levels throughout an entire recording chain - whether those signals are generated by a single mic or a whole passel of inputs running through a large mixer. In fact, it's in the realm of complex mixing consoles that gain structure is MOST critical, since the very tool implies adding multiple sounds and mixing them down into an appropriate master output level. But the lessons you can learn on how to set the gain structure of a large mixer - particularly setting the trim correctly and optimizing each signal in it's individual channel strip - is precisely the central skill required to properly set the gain structure of a single channel of a mic feeding your camcorder.

Properly trimmed, a signal hitting your camcorder will allow you to use that camcorder's volume control to USEFULLY limit the chance of the signal falling apart prior to being written to tape or disc.

Again, I'd do a careful search on "gain structure" and you should get a lot of useful information on how to set levels at each stage of an audio recording chain, whether that chain is a simple mic to camera mic input, or the more complex process of taking, say, a house audio feed, running it through a camera side sub-mixer - and then into your camera.

I stated it as clearly as I know how in my first post in this thread. We're talking about the "Trim" settings.

My apologies, Bill. I was replying to you. I was mistaken in my reply, too. I did a search on "gain structure" (why I typed "control" only heaven knows). How can I be sure? Because the same articles came up in the search as the other day.

Like I said, I am not a "audio" person, per se. The articles I read presumes the reader is at the same level of expertise as the writer.

All I'm searching is a simple, straight forward, non-technical explanation of the Trim settings and how to apply them. At this point, based on what has been posted in this thread so far, I am able to set the Trim with some degree of accuracy.

My second point is Sony should have provided an explantion in the manual on applying the Trim settings. They didn't.

As to the first, consider this.

A "trim" control essentially determines the RANGE that a volume control will adjust. It does so by limiting (or boosting, if an amplifying stage is involved) the level of the signal that is subsequently "seen" by that volume control.

The proper process of setting a good gain structure is to typically FIRST set the volume control a modest amount below the upper range of it's pass through capability - THEN to TRIM the signal presented to that volume control, such that when the volume control is pushed toward it's maximum, the signal stays within an optimum range of signal strength.

(If you look at analog mixing boards you'll often see a graphic indicator on the mixer's faceplate 70-80% or so down from the top of the sliders where the sliders pass optimal audio. At or near the top of this "sweet spot" range is where those volume sliders are typically set prior to adjusting the GAIN into that channel strip)

As to your second point. Welcome to how Video manuals typically discuss audio issues. Which is to say barely, if at all.

Hope this helps.