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Old November 15th, 2017, 07:15 AM   #1
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External audio recorder

Hi,

I've been using an internal audio recording capability on my Canon C100, and it's been fine. I just decided to step up my audio and got myself Sound Devices PreMix 3. I have 2 questions related to general external audio recording, not specific to my recorder.

1. What is the reason for people to hook up the external recorder to the camera? The reviews I've read, the videos I watch all show how to hook up an external audio recorder to the camera but none of them tell me why I would want to do that. Can someone explain the reasons?

2. I'd like to set gain levels on my recorder, from reading blogs etc. I see there are many ways of going about it. It's not just dialing the knob and that's it. There is a way to set the sensitivity and then gain etc. If I just set the knob to about a middle, the microphone has to be right at someone's mouth in order to get adequate levels (I was aiming for between -20 and -12, although in my camera I would normally aim for in between -6 and 0). And that's fine to have it right at their mouth if I'm recording just audio but if I'm also recording a video and use the mic on a boom, no way I can get adequate levels. Can someone tell to me what I'm overlooking?

Thanks
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Old November 15th, 2017, 09:34 AM   #2
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Re: External audio recorder

Hello Kathy, this will be an interesting question to read everyone's response on. I also use a C100 and am considering an external recorder.

I don't have much experience with this so I don't have any suggestions other then the external recorder offers greater control, maybe easer control of audio going into the camera.

My question would be; can you get stereo (two channel out) from the recorder into the camera? Or must you do this in post?

Thanks, KPO
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Old November 15th, 2017, 09:45 AM   #3
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Re: External audio recorder

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Originally Posted by Kevin O'Connor View Post
My question would be; can you get stereo (two channel out) from the recorder into the camera? Or must you do this in post?

Thanks, KPO
Hi Kevin,

Since you are asking this question, can you tell me what would be the reason to get the audio (regardless of mono or stereo) into the camera? That's actually my question #1.
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Old November 15th, 2017, 10:00 AM   #4
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Re: External audio recorder

Hi Kathy,

The main reason for hooking up the external recorder to the camera is that you get better quality pre amps in the external recorder and the mix going into the camera will give you exactly what the premix is hearing, so no sound delay difference that you may get between camera mic and source. Personally I find using an external mix for most of my video work generally not practical, as I don't want to worry about cables, but it is likely to give you the best sound quality directly to the camera. You can of course just use the recording from the Premix and synch it up later which is what I prefer to do.

To use an external Premix input, you need to get the levels to the a premix right first. I would set the output level to 0db, and bring up the input gain until you are getting the correct level on the loudest sound. if there are likely to be some unexpected sudden peaks, back off the gain by a few dB. Once the Premix is set up, you can then adjust the input levels into the camera in the same way.

Some people make the mistake of setting the input gain too high which gives clipping on the input and try to control it by reducing the volume controls. Having the input gain too low results in having to bring up the volume controls which also brings up any system noise. It's always a balancing act to get it right and under ideal circumstances you would have a proper sound check before the main event.

Roger
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Old November 15th, 2017, 10:18 AM   #5
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Re: External audio recorder

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Originally Posted by Roger Gunkel View Post
Hi Kathy,

The main reason for hooking up the external recorder to the camera is that you get better quality pre amps in the external recorder and the mix going into the camera will give you exactly what the premix is hearing, so no sound delay difference that you may get between camera mic and source. Personally I find using an external mix for most of my video work generally not practical, as I don't want to worry about cables, but it is likely to give you the best sound quality directly to the camera. You can of course just use the recording from the Premix and synch it up later which is what I prefer to do.

To use an external Premix input, you need to get the levels to the a premix right first. I would set the output level to 0db, and bring up the input gain until you are getting the correct level on the loudest sound. if there are likely to be some unexpected sudden peaks, back off the gain by a few dB. Once the Premix is set up, you can then adjust the input levels into the camera in the same way.

Some people make the mistake of setting the input gain too high which gives clipping on the input and try to control it by reducing the volume controls. Having the input gain too low results in having to bring up the volume controls which also brings up any system noise. It's always a balancing act to get it right and under ideal circumstances you would have a proper sound check before the main event.

Roger
Thanks Roger but I still don't understand. I understand that the external recorder has better preamps. So, I record to external recorder, then sync in post, that's the way I understand you work with an external recorder. Why are people hooking up the external recorder to the camera, if you hook up the recorder to the camera, are you no longer recording to the external recorder but to the camera? If so, what's the point of having an external recorder if you can go straight to the camera. There is something obvious I don't understand. Do you bypass camera preamp when you connect external recorder to the camera? Is that what I'm missing?
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Old November 15th, 2017, 10:42 AM   #6
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Re: External audio recorder

Recording sound separately goes back to film production. With a couple exceptions there was no sound in film cameras, so an independent sound recorder was standard practice.

However, post synchronization had many potential pitfalls. Crystal sync, timecode, bloop lights, sync drift... it was the dark ages by comparison to today’s tools.

This workflow was resurrected for dSLRs to use cheap home studio recorders, and NLE companies responded with plugins and native functions for post sync. But, while these methods are amazing and much more reliable than pre-digital workflows, it is still possible to get into trouble.

You need some sort of recording on the camera to use modern digital post sync. On a dSLR the on-board mic may be very crappy indeed, or, covered by the operator’s hand, or, be too distant to get dialog in a noisy location. If the post sync tools don’t have distinct dialog on-camera, they can’t do their sync magic.

That’s why many people feed their recorder’s output to their dSLR, perhaps with a cable that pads the recorder’s headphone output down to mic level.

And, surprise, some of them found that the resulting camera recording was fine for dialog, or, at least they were satisfied. It depends. Whatever.

In your situation you could run the recorder tethered or untethered from the camera with no special cables, just XLR. You just need to be darn sure you have sound on the camera to sync to later. If I use this workflow at all, I’ll usually go untethered. But recordists are a pretty conservative group, and there’s certainly nothing wrong with a belt and suspenders approach.

(EDIT: 3.5mm output from the mixer, you’d need a 3.5 to XLR, easy to break!)

**********************************
I’ve not used the new SD mixer/recorders, but they look great, SD is (arguably) the best, certainly with the MixPre 3, 6, and 10 they’ve established a new price point for a capable mixer/recorder.

But sensitivity aka. preamp gain aka. trim is pretty much the same across all mixers. Two volume controls for one input channel is confusing. Why would you need that? Think of them as sensitivity (set once for a scene) and fader (ride as needed during a scene).

The purposes of sensitivity / gain are to:
a) set the source’s volume to a level that is good for the performance of the preamp, (which takes your source from mic level to line level inside the mixer), and,
b) set the source’s volume to a level that is good for your control of the mix using the fader, (physical control of the knob when mixing - the knob is somewhere roughly in the middle of its range)

Getting the sensitivity wrong can mean that the preamp is overdriven and the source is distorted. It can mean that you’re trying to set the fader at 0.25 on a 1 to 10 scale. Etc.
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Last edited by Seth Bloombaum; November 15th, 2017 at 11:23 AM. Reason: No XLR outputs from this mixer!
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Old November 15th, 2017, 10:57 AM   #7
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Re: External audio recorder

Quote:
Originally Posted by Kathy Smith View Post
Thanks Roger but I still don't understand. I understand that the external recorder has better preamps. So, I record to external recorder, then sync in post, that's the way I understand you work with an external recorder. Why are people hooking up the external recorder to the camera, if you hook up the recorder to the camera, are you no longer recording to the external recorder but to the camera? If so, what's the point of having an external recorder if you can go straight to the camera. There is something obvious I don't understand. Do you bypass camera preamp when you connect external recorder to the camera? Is that what I'm missing?
You would interface with the camera to give yourself a solid source to sync your recorder tracks to. You could use the camera mic for this but you might be too distant from the source and could make it harder to sync due to a more diffuse sound. Think of the MixPre 3 as both a mixer and a recorder. You're sending a mix to the camera to sync to and you're recording separated tracks on the MixPre 3.
If the MixPre3 has a tone generator you use that to calibrate its meters to the cameras meters. The separate recorder gives you more inputs, better control of the levels, better pre amps, and separate audio tracks of each source.
Gain staging is still important so make sure you understand how to optimally set up your recorder's input and then the output will be in the ball park as well. I'm echoing much of what Seth already noted.
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Old November 15th, 2017, 11:01 AM   #8
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Re: External audio recorder

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Originally Posted by Seth Bloombaum View Post
Recording sound separately goes back to film production. With a couple exceptions there was no sound in film cameras, so an independent sound recorder was standard practice.

However, post synchronization had many potential pitfalls. Crystal sync, timecode, bloop lights, sync drift... it was the dark ages by comparison to todayís tools.

This workflow was resurrected for dSLRs to use cheap home studio recorders, and NLE companies responded with plugins and native functions for post sync. But, while these methods are amazing and much more reliable than pre-digital workflows, it is still possible to get into trouble.

You need some sort of recording on the camera to use modern digital post sync. On a dSLR the on-board mic may be very crappy indeed, or, covered by the operatorís hand, or, be too distant to get dialog in a noisy location. If the post sync tools donít have distinct dialog on-camera, they canít do their sync magic.

Thatís why many people feed their recorderís output to their dSLR, perhaps with a cable that pads the recorderís headphone output down to mic level.

And, surprise, some of them found that the resulting camera recording was fine for dialog, or, at least they were satisfied. It depends. Whatever.

In your situation you could run the recorder tethered or untethered from the camera with no special cables, just XLR. You just need to be darn sure you have sound on the camera to sync to later. If I use this workflow at all, Iíll usually go untethered. But recordists are a pretty conservative group, and thereís certainly nothing wrong with a belt and suspenders approach.

**********************************
Iíve not used the new SD mixer/recorders, but they look great, SD is (arguably) the best, certainly with the MixPre 3, 6, and 10 theyíve established a new price point for a capable mixer/recorder.

But sensitivity aka. preamp gain aka. trim is pretty much the same across all mixers. Two volume controls for one input channel is confusing. Why would you need that? Think of them as sensitivity (set once for a scene) and fader (ride as needed during a scene).

The purposes of sensitivity / gain are to:
a) set the sourceís volume to a level that is good for the performance of the preamp, (which takes your source from mic level to line level inside the mixer), and,
b) set the sourceís volume to a level that is good for your control of the mix using the fader, (physical control of the knob when mixing - the knob is somewhere roughly in the middle of its range)

Getting the sensitivity wrong can mean that the preamp is overdriven and the source is distorted. It can mean that youíre trying to set the fader at 0.25 on a 1 to 10 scale. Etc.
Thanks Seth. I would like to record to the recorder and sync in post. I know how to do that and I do know that I still need audio out of the camera for syncing. From the explanations it seems too convoluted to hook up the recorder to the camera, so I will stick with external recording and syncing in post.
I'm still unsure how to set gain/sensitivity. The MixPre can be used in 2 modes BASIC and ADVANCED. ADVANCED more is way more than I need, I don't need a mix, isolated tracks, I don't need to fade. In BASIC mode the knobs are simply "gain" knobs. If I set the gain to the middle of the knob scale, my levels read between -30 and -20 close to -20 most of the time, and that's having the mic right next to the mouth. If I use the mic on a boom the levels read between -40 and -30. That seems wrong to me. Am I overseeing something?
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Old November 15th, 2017, 11:03 AM   #9
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Re: External audio recorder

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Originally Posted by Bernie Beaudry View Post
You would interface with the camera to give yourself a solid source to sync your recorder tracks to. You could use the camera mic for this but you might be too distant from the source and could make it harder to sync due to a more diffuse sound. Think of the MixPre 3 as both a mixer and a recorder. You're sending a mix to the camera to sync to and you're recording separated tracks on the MixPre 3.
If the MixPre3 has a tone generator you use that to calibrate its meters to the cameras meters. The separate recorder gives you more inputs, better control of the levels, better pre amps, and separate audio tracks of each source.
Gain staging is still important so make sure you understand how to optimally set up your recorder's input and then the output will be in the ball park as well. I'm echoing much of what Seth already noted.
OK, so I misunderstood, from your explanation I understand that the audio you send to the camera is simply to have a better audio for syncing in post, right?
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Old November 15th, 2017, 11:15 AM   #10
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Re: External audio recorder

Quote:
Originally Posted by Kathy Smith View Post
Hi,

I've been using an internal audio recording capability on my Canon C100, and it's been fine. I just decided to step up my audio and got myself Sound Devices PreMix 3. I have 2 questions related to general external audio recording, not specific to my recorder.

1. What is the reason for people to hook up the external recorder to the camera? The reviews I've read, the videos I watch all show how to hook up an external audio recorder to the camera but none of them tell me why I would want to do that. Can someone explain the reasons?

2. I'd like to set gain levels on my recorder, from reading blogs etc. I see there are many ways of going about it. It's not just dialing the knob and that's it. There is a way to set the sensitivity and then gain etc. If I just set the knob to about a middle, the microphone has to be right at someone's mouth in order to get adequate levels (I was aiming for between -20 and -12, although in my camera I would normally aim for in between -6 and 0). And that's fine to have it right at their mouth if I'm recording just audio but if I'm also recording a video and use the mic on a boom, no way I can get adequate levels. Can someone tell to me what I'm overlooking?

Thanks
Generally you set the fader (the main knob, at 12 o'clock) and dial the sensitivity up until you're getting close to the level you want. Then if you need more or less gain you use the fader to adjust that. It's a two stage input. Think of the sensitivity as coarse gain, and the fader as your smooth adjustment. If the coarse gain is set too low you'll end up with the fader turned way up and it'll get noisy. If the coarse gain is too high the input could distort and the fader will be barely turned up. You want to set it up so you have flexibility from 12 o'clock to about three quarters up on your fader. You can go for the same level on the recorder as you do on the camera as it has a much better audio circuit. If you use tone to line up your recorder meters with the camera meters they should look pretty close to the same and should react about the same. Are you going into the camera at mic level or line level? You could do either one depending on what gives you a more usable signal. If its only for syncing then don't worry too much about it as long as its solid.
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Old November 15th, 2017, 11:17 AM   #11
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Re: External audio recorder

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Originally Posted by Kathy Smith View Post
Hi Kevin,

Since you are asking this question, can you tell me what would be the reason to get the audio (regardless of mono or stereo) into the camera? That's actually my question #1.
Sorry to high jack your topic. My guess to your question, and I have not read all the response yet, is; It's good to have the exact copy of the audio track your recorder has collected on your camera so you can sync the two in post.

Okay now I'll read everyone response.

Thanks, KPO.
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Old November 15th, 2017, 11:19 AM   #12
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Re: External audio recorder

Quote:
Originally Posted by Bernie Beaudry View Post
You would interface with the camera to give yourself a solid source to sync your recorder tracks to. You could use the camera mic for this but you might be too distant from the source and could make it harder to sync due to a more diffuse sound. Think of the MixPre 3 as both a mixer and a recorder. You're sending a mix to the camera to sync to and you're recording separated tracks on the MixPre 3.
If the MixPre3 has a tone generator you use that to calibrate its meters to the cameras meters. The separate recorder gives you more inputs, better control of the levels, better pre amps, and separate audio tracks of each source.
Gain staging is still important so make sure you understand how to optimally set up your recorder's input and then the output will be in the ball park as well. I'm echoing much of what Seth already noted.
Quote:
Originally Posted by Bernie Beaudry View Post
Generally you set the fader (the main knob, at 12 o'clock) and dial the sensitivity up until you're getting close to the level you want. Then if you need more or less gain you use the fader to adjust that. It's a two stage input. Think of the sensitivity as coarse gain, and the fader as your smooth adjustment. If the coarse gain is set too low you'll end up with the fader turned way up and it'll get noisy. If the coarse gain is too high the input could distort and the fader will be barely turned up. You want to set it up so you have flexibility from 12 o'clock to about three quarters up on your fader. You can go for the same level on the recorder as you do on the camera as it has a much better audio circuit. If you use tone to line up your recorder meters with the camera meters they should look pretty close to the same and should react about the same. Are you going into the camera at mic level or line level? You could do either one depending on what gives you a more usable signal. If its only for syncing then don't worry too much about it as long as its solid.
Hi Bernie, I'm not going to the camera at all.
Also, you said "Are you going into the camera at mic level or line level? You could do either one depending on what gives you a more usable signal. If its only for syncing then don't worry too much about it as long as its solid." I thought that audio was just for syncing, if not, what else can I use that audio for?
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Old November 15th, 2017, 11:23 AM   #13
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Re: External audio recorder

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Originally Posted by Kevin O'Connor View Post
Sorry to high jack your topic. My guess to your question, and I have not read all the response yet, is; It's good to have the exact copy of the audio track your recorder has collected on your camera so you can sync the two in post.

Okay now I'll read everyone response.

Thanks, KPO.
I see, I use internal speakers on the camera for syncing, never had issues. And if the only reason to have the recorder hooked up to the camera so you get a copy of audio in your camera for syncing purposes, why would you care whether it's stereo or mono?
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Old November 15th, 2017, 11:27 AM   #14
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Re: External audio recorder

Quote:
Originally Posted by Kathy Smith View Post
...I'm still unsure how to set gain/sensitivity. The MixPre can be used in 2 modes BASIC and ADVANCED. ADVANCED more is way more than I need, I don't need a mix, isolated tracks, I don't need to fade. In BASIC mode the knobs are simply "gain" knobs. If I set the gain to the middle of the knob scale, my levels read between -30 and -20 close to -20 most of the time, and that's having the mic right next to the mouth. If I use the mic on a boom the levels read between -40 and -30. That seems wrong to me. Am I overseeing something?
Not having used this mixer, and not having time to research, I’ll speculate. Take it for what it’s worth.

If the BASIC mode really does turn the knobs into pre-preamp gain controls (trims, sensitivity) then crank them up so your peak volumes hit -18db, or, -12db, depending on how adventurous/conservative you are.

Test and listen... for corporate talking heads (do I remember that’s a lot of what you do?) I’d peak at -12db.

Running faders at about 12 o’clock is for faders, not preamp gain! You’re saying you can make the knobs into gain controls? Run them right up past 12, way past as needed.

PS. That’s a very interesting function SD has put in. I like it!
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Old November 15th, 2017, 11:35 AM   #15
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Re: External audio recorder

Quote:
Originally Posted by Kathy Smith View Post
I see, I use internal speakers on the camera for syncing, never had issues. And if the only reason to have the recorder hooked up to the camera so you get a copy of audio in your camera for syncing purposes, why would you care whether it's stereo or mono?
Your right, now that I have read all the feedback I only need one channel or mono into the camera to sync in post.

Thanks, KPO.
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