Audio Question From Manual at DVinfo.net

Jeff Stern · January 5th, 2009, 08:46 PM

I'm doing my first live shoot with my A1 on Thursday and was reading the manual about attaching external microphones and noticed that it mentioned "Use commercially available microphones with a cable no longer than 3m" (page 48)

I'm shooting a concert in my auditorium and my plan was to put the camera at the back of the auditorium and connect one XLR to the PA system that's going to be on stage (which is only going to be playing back the vocal mics and not the instruments) and another to a condenser mic front center.

Of course the wires I was going to run to connect the audio were going to be much longer than 3 meters, is this going to be a problem? Anybody know why the manual warns against it?

And another question, when I import the footage with 2 XLR mics and the on-board cam's mic (for crowd ambience), will I be getting six audio tracks on Final Cut (Express) or just two?

Thank you!

Tripp Woelfel · January 5th, 2009, 09:26 PM

Quote:

Originally Posted by Jeff Stern

I'm doing my first live shoot with my A1 on Thursday and was reading the manual about attaching external microphones and noticed that it mentioned "Use commercially available microphones with a cable no longer than 3m" (page 48) Of course the wires I was going to run to connect the audio were going to be much longer than 3 meters, is this going to be a problem? Anybody know why the manual warns against it?

Maybe, and I don't. If it helps, I shot a wedding last summer with a wired lav connected to the camera with 25 feet of cable. No problems.

The only reason I can think of for the admonition is that long cable runs can result in signal loss. XLR connections are balanced and can run a long way without problems. I don't know if there's something peculiar to the A1 that's different.

Quote:

Originally Posted by Jeff Stern

And another question, when I import the footage with 2 XLR mics and the on-board cam's mic (for crowd ambience), will I be getting six audio tracks on Final Cut (Express) or just two?

Two, and you won't get audio from the onboard mic. You cannot do both at the same time. It's either XLR or on board. You should also know that unless you have the new A1s you won't be able to take a line level out from the mixing board and mic level from the mic at the same time without some help. With the original A1 XLRs, you only get to do mic level or line level. Not both. The A1s can do both.

Jeff Stern · January 6th, 2009, 05:06 AM

Quote:

Originally Posted by Tripp Woelfel

Two, and you won't get audio from the onboard mic. You cannot do both at the same time. It's either XLR or on board. You should also know that unless you have the new A1s you won't be able to take a line level out from the mixing board and mic level from the mic at the same time without some help. With the original A1 XLRs, you only get to do mic level or line level. Not both. The A1s can do both.

What you're saying is, my setup won't work? They're both XLR ports, can the camera really read them as two different output sources? And if that's the case, it would be OK if I had two mics, right?

Allan Black · January 6th, 2009, 06:02 AM

I think Canon is refering to the unbalanced 3.5mm mic input when they say, 'no cable longer than 3 meters' I've run longer than that but they're covering their butt. Long unbalanced mic cables can be prone to hum in the audio and radio frequency interference, RF.

Yes you can run 2 separate mono XLR mics and get 2 separate A1 mono audio tracks.

But you might look at renting an audio mixer for this occasion, one that has 4 XLR mic and line inputs with two balanced XLR line outputs and has a limiter to stop the levels reaching distortion on your tape.

That way you could feed mic and line to your A1 line inputs, have better audio level control which I think you'll need during the concert. Riding the levels while recording is a pain on the A1. Have you got an audio guy to help out?

Cheers.

Tripp Woelfel · January 6th, 2009, 06:09 AM

Jeff... I guess I'm not really sure which setup you're referring to.

Given your setup with the XH A1 (not A1s), you can have two simultaneous XLR inputs. They can be set both as mic level or both as line level. Whilst the XLR inputs are active you will not be able to use the on board mic. Your choice there is either/or. Not both at the same time.

You could take the output from the mixing board and convert it from line to mic level, or you can get a mic mixer to bring the mic up to line level. The first option is cheaper but the second will give you more long-term flexibility. The second option can give you more input sources, typically three mixed down to one XLR input.

Basically, much of what you suggested in your original post cannot all be done at the same time given the kit you describe. But, there are options to get you where you want. It will just take some more gear and money.

Brad Tyrrell · January 6th, 2009, 12:35 PM

Seconding Tripp's advice.

Also, I've now run up to 200 feet of xlr to a pzm with phantom supplied from the Xh-A1 with no problems.

Careful, "PA system" could mean just about anything. I've had a couple of disasters being overly trusting of the guy on the board.

The limiter affect with the XH-a1 on auto isn't bad, but something with a limiter between the board and the camera always feels safer.

Jeff Stern · January 6th, 2009, 04:33 PM

Thank you Tripp, Brad and Allen. So let me just recap real quick, and I appreciate your patience and help! Clearly, I'm still learning the camera and have yet to work with audio, so I truly appreciate the help.

I'm going to set the camera up in the back of the auditorium and run...

A XLR to a PA System broadcasting the vocal mics and
A XLR to a Condensor Mic in front of the stage to pick up the rest of the sound
I'll convert the PA to mic level (sidenote: is there much of a difference between mic level and line level?)

This will be an O.K. working set up for the night for someone with limited opportunities and a very small budget?

Chris Soucy · January 6th, 2009, 05:23 PM

You haven't said (er, have you?) how big this auditorium is.

If the cable run from the mic to the camera is a long one, it might (if you had the time, but I don't think you do) pay to have something like this up near the stage to boost the mic level up to Line.

Give you the opportunity to run both inputs at line.

Australian Monitor | AMIS-PRE1 - Microphone Preamp | PRE1 | B&H

Given your budget restraints, a relatively cheap alternative to the suggested mixer route.

Just a thought.

CS

PS: Other possibles...........

Rolls | MP13 Mini Microphone Preamp | MP13 | B&H Photo Video

ART | Tube MP Studio V3 Microphone Preamp | TUBE MP STUDIO V3

This looks cute.........

Rode | D-PowerPlug - In-Line Cable-Mounted | D-POWER PLUG | B&H

etc, etc.........

Jeff Stern · January 6th, 2009, 08:23 PM

Yea, that's not much money at all. It's just too bad that the expected delivery date is the day after the concert and I'm just not up for spending $30 on the overnight shipping nor am I willing to take the $20, 4hr train ride into the city to go to B&H tomorrow. But I'll certainly keep it in mind if I end up doing more live events similar to this.

How big IS in fact the difference between a line out and a mic out in terms of sound quality though?

Chris Soucy · January 6th, 2009, 09:04 PM

Well, it's not really a question of quality, per see, in theory the quality of both as they emerge from their respective sources would be identical.

The difference is in what happens to them during transmission down a line.

I won't start quoting figures as they'll probably be wrong, but look at it this way.

As you pump both signals down a long cable, they both pick up noise and, due to cable resistance and capacitance, start losing signal.

The low level mic output doesn't have to pick up more than a millivolt or so of noise to be in pretty bad shape.

The much higher line level would be hardly bothered by the same amount of noise.

As for losses (getting on shaky ground here so don't quote me) I believe the amount of signal loss per yard/ metre is the same despite the original signal level.

So, if the original signal level was 10 millivolts and the loss over 10 yards was .5 millivolts/ yard, you ain't got much left at the other end.

If the original signal was instead 500 millivolts with the same loss, it's hardly noticeable.

[I declare at this point all the values have been changed to protect the innocent (or, in my case, the ignorant)].

Basically, the more grunt at the start, the better.

Anyway, some stuff to keep in mind for next time.

I would add, none those items I listed would rank in a pro's list of the top 100, but it's your budget you're spending, not theirs.

Hope the gig goes well.

CS

Petri Kaipiainen · January 9th, 2009, 04:28 AM

If I remember correctly line level signals are something like 40 dB "louder" than mic level, which in other type of math means 10000 times stronger. As the noise components entering cabeling is the same for both, it is easy to understand why noise is not much of a problem with line level signals. That does not mean long mic cables do not work, no, it is possible to have phantom powered mic cable runs even hundreds of meters long, if there is no RF noise present. But line level is always safer.

Don Palomaki · January 11th, 2009, 10:16 AM

Consumer line level is typically -10 dB relative to 1 volt, is unbalanced, an often implies using an input impedance on the order of 10k ohms or higher, and higher output impedance as well. The higher impedance make it more susceptible to high frequency loss in longer cables, Shielded audio cable typically has on the order of 30mmf capacitance per foot. Thus with a 10kohm source impedance and 50 feet of cable you could expect around 3 dB attenuation at 10 kHz due to cable capacitance alone, not considering any noise pickup or other factors. With 600 ohm source you can nearly 1000 feet before you have the same capacitance loss.

Professional line level is typically +4 dB and balanced, and is often referenced to a 600 ohm input impedance.

MIC level covers awid range of values and depends on the mic. With respect to mixers, it often means -35 dB output level and a 600 ohm source or input impedance is implied.

However, for purposes of camcorder input sensitivity it typically is around -55 dB, and the MIC ATT setting is typically around -35 dB, give or take. On the Canon the input impedance for MIC level inputs is nominally 600 ohms.

However, actual input and output impedances vary widely depending on the gear you are using, and are a bit less critical thatn they were with the tube gear of the dim distant past. A couple thing to keep in mind that for best results the input impedance normally should not be higher than the output impedance of the source, higher impedance inputs tend to be more susceptible to noise induced into the cables, and balanced is generally better than unbalance provided it is terminated with a balanced input. Audio is generally much more forgiving of impedance matches than RF.

January 5th, 2009, 08:46 PM	#1
Jeff Stern New Boot Join Date: Dec 2008 Location: Long Island, NY Posts: 10	Audio Question From Manual I'm doing my first live shoot with my A1 on Thursday and was reading the manual about attaching external microphones and noticed that it mentioned "Use commercially available microphones with a cable no longer than 3m" (page 48) I'm shooting a concert in my auditorium and my plan was to put the camera at the back of the auditorium and connect one XLR to the PA system that's going to be on stage (which is only going to be playing back the vocal mics and not the instruments) and another to a condenser mic front center. Of course the wires I was going to run to connect the audio were going to be much longer than 3 meters, is this going to be a problem? Anybody know why the manual warns against it? And another question, when I import the footage with 2 XLR mics and the on-board cam's mic (for crowd ambience), will I be getting six audio tracks on Final Cut (Express) or just two? Thank you!

January 6th, 2009, 05:23 PM	#8
Chris Soucy Inner Circle Join Date: Feb 2007 Location: Fairfield, Dunedin, New Zealand Posts: 3,688 Images: 18	Hi Jeff................ You haven't said (er, have you?) how big this auditorium is. If the cable run from the mic to the camera is a long one, it might (if you had the time, but I don't think you do) pay to have something like this up near the stage to boost the mic level up to Line. Give you the opportunity to run both inputs at line. Australian Monitor \| AMIS-PRE1 - Microphone Preamp \| PRE1 \| B&H Given your budget restraints, a relatively cheap alternative to the suggested mixer route. Just a thought. CS PS: Other possibles........... Rolls \| MP13 Mini Microphone Preamp \| MP13 \| B&H Photo Video ART \| Tube MP Studio V3 Microphone Preamp \| TUBE MP STUDIO V3 This looks cute......... Rode \| D-PowerPlug - In-Line Cable-Mounted \| D-POWER PLUG \| B&H etc, etc......... Last edited by Chris Soucy; January 6th, 2009 at 06:26 PM. Reason: +

January 6th, 2009, 09:04 PM	#10
Chris Soucy Inner Circle Join Date: Feb 2007 Location: Fairfield, Dunedin, New Zealand Posts: 3,688 Images: 18	Hi............... Well, it's not really a question of quality, per see, in theory the quality of both as they emerge from their respective sources would be identical. The difference is in what happens to them during transmission down a line. I won't start quoting figures as they'll probably be wrong, but look at it this way. As you pump both signals down a long cable, they both pick up noise and, due to cable resistance and capacitance, start losing signal. The low level mic output doesn't have to pick up more than a millivolt or so of noise to be in pretty bad shape. The much higher line level would be hardly bothered by the same amount of noise. As for losses (getting on shaky ground here so don't quote me) I believe the amount of signal loss per yard/ metre is the same despite the original signal level. So, if the original signal level was 10 millivolts and the loss over 10 yards was .5 millivolts/ yard, you ain't got much left at the other end. If the original signal was instead 500 millivolts with the same loss, it's hardly noticeable. [I declare at this point all the values have been changed to protect the innocent (or, in my case, the ignorant)]. Basically, the more grunt at the start, the better. Anyway, some stuff to keep in mind for next time. I would add, none those items I listed would rank in a pro's list of the top 100, but it's your budget you're spending, not theirs. Hope the gig goes well. CS

January 11th, 2009, 10:16 AM	#12
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	Consumer line level is typically -10 dB relative to 1 volt, is unbalanced, an often implies using an input impedance on the order of 10k ohms or higher, and higher output impedance as well. The higher impedance make it more susceptible to high frequency loss in longer cables, Shielded audio cable typically has on the order of 30mmf capacitance per foot. Thus with a 10kohm source impedance and 50 feet of cable you could expect around 3 dB attenuation at 10 kHz due to cable capacitance alone, not considering any noise pickup or other factors. With 600 ohm source you can nearly 1000 feet before you have the same capacitance loss. Professional line level is typically +4 dB and balanced, and is often referenced to a 600 ohm input impedance. MIC level covers awid range of values and depends on the mic. With respect to mixers, it often means -35 dB output level and a 600 ohm source or input impedance is implied. However, for purposes of camcorder input sensitivity it typically is around -55 dB, and the MIC ATT setting is typically around -35 dB, give or take. On the Canon the input impedance for MIC level inputs is nominally 600 ohms. However, actual input and output impedances vary widely depending on the gear you are using, and are a bit less critical thatn they were with the tube gear of the dim distant past. A couple thing to keep in mind that for best results the input impedance normally should not be higher than the output impedance of the source, higher impedance inputs tend to be more susceptible to noise induced into the cables, and balanced is generally better than unbalance provided it is terminated with a balanced input. Audio is generally much more forgiving of impedance matches than RF. __________________ dpalomaki@dspalomaki.com

January 6th, 2009, 06:02 AM	#4
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,918	I think Canon is refering to the unbalanced 3.5mm mic input when they say, 'no cable longer than 3 meters' I've run longer than that but they're covering their butt. Long unbalanced mic cables can be prone to hum in the audio and radio frequency interference, RF. Yes you can run 2 separate mono XLR mics and get 2 separate A1 mono audio tracks. But you might look at renting an audio mixer for this occasion, one that has 4 XLR mic and line inputs with two balanced XLR line outputs and has a limiter to stop the levels reaching distortion on your tape. That way you could feed mic and line to your A1 line inputs, have better audio level control which I think you'll need during the concert. Riding the levels while recording is a pain on the A1. Have you got an audio guy to help out? Cheers.

January 6th, 2009, 06:09 AM	#5
Tripp Woelfel Trustee Join Date: Jan 2008 Location: North Conway, NH Posts: 1,745	Jeff... I guess I'm not really sure which setup you're referring to. Given your setup with the XH A1 (not A1s), you can have two simultaneous XLR inputs. They can be set both as mic level or both as line level. Whilst the XLR inputs are active you will not be able to use the on board mic. Your choice there is either/or. Not both at the same time. You could take the output from the mixing board and convert it from line to mic level, or you can get a mic mixer to bring the mic up to line level. The first option is cheaper but the second will give you more long-term flexibility. The second option can give you more input sources, typically three mixed down to one XLR input. Basically, much of what you suggested in your original post cannot all be done at the same time given the kit you describe. But, there are options to get you where you want. It will just take some more gear and money.

January 6th, 2009, 12:35 PM	#6
Brad Tyrrell Major Player Join Date: Oct 2003 Location: Morristown, New Jersey Posts: 249	Seconding Tripp's advice. Also, I've now run up to 200 feet of xlr to a pzm with phantom supplied from the Xh-A1 with no problems. Careful, "PA system" could mean just about anything. I've had a couple of disasters being overly trusting of the guy on the board. The limiter affect with the XH-a1 on auto isn't bad, but something with a limiter between the board and the camera always feels safer.

January 6th, 2009, 04:33 PM	#7
Jeff Stern New Boot Join Date: Dec 2008 Location: Long Island, NY Posts: 10	Thank you Tripp, Brad and Allen. So let me just recap real quick, and I appreciate your patience and help! Clearly, I'm still learning the camera and have yet to work with audio, so I truly appreciate the help. I'm going to set the camera up in the back of the auditorium and run... A XLR to a PA System broadcasting the vocal mics and A XLR to a Condensor Mic in front of the stage to pick up the rest of the sound I'll convert the PA to mic level (sidenote: is there much of a difference between mic level and line level?) This will be an O.K. working set up for the night for someone with limited opportunities and a very small budget?

January 6th, 2009, 08:23 PM	#9
Jeff Stern New Boot Join Date: Dec 2008 Location: Long Island, NY Posts: 10	Yea, that's not much money at all. It's just too bad that the expected delivery date is the day after the concert and I'm just not up for spending $30 on the overnight shipping nor am I willing to take the $20, 4hr train ride into the city to go to B&H tomorrow. But I'll certainly keep it in mind if I end up doing more live events similar to this. How big IS in fact the difference between a line out and a mic out in terms of sound quality though?

January 9th, 2009, 04:28 AM	#11
Petri Kaipiainen Major Player Join Date: Apr 2007 Location: Espoo Finland Posts: 380	If I remember correctly line level signals are something like 40 dB "louder" than mic level, which in other type of math means 10000 times stronger. As the noise components entering cabeling is the same for both, it is easy to understand why noise is not much of a problem with line level signals. That does not mean long mic cables do not work, no, it is possible to have phantom powered mic cable runs even hundreds of meters long, if there is no RF noise present. But line level is always safer.