Record three lavs with 2 audio input camera
 

I have to record three lavs but my Canon XF305 has only two external audio inputs.

What is the easiest way to record 3 into 2?

Re: Record three lavs with 2 audio input camera
 

This is why they make audio mixers. Is this a one-off need? Do you need to acquire a mixer for future productions? What is your budget? What microphones, camera, etc. are you using?

Re: Record three lavs with 2 audio input camera
 

As I said in my original post, I am using a Canon XF305 camera. The microphones are Sennheiser. I don't anticipate needing to use 3 mics in the future and would like to spend as little as possible. I would also like to keep it as simple as possible as it is a one-man shoot.

Re: Record three lavs with 2 audio input camera
 

Buy a Zoom H4N or some other cheap audio recorder that takes XLR. Run two to the camera and one to the recorder. Sure you will have to sync them together later but it is a much better solution than trying to mix down to 2 channels and dealing with phasing issues (depending on distance of course).

Re: Record three lavs with 2 audio input camera
 

Also check out the Tascam DR-40 - field recorder accepts XLR (with phantom power) for less than $200.

Re: Record three lavs with 2 audio input camera
 

Rent a mixer from Trew audio in your area.

Cheers.

Re: Record three lavs with 2 audio input camera
 

Have to agree with the others use a mixer, as another alternative that hasn't been mentioned use a second camera this will then give you 4 inputs (2 on each) as well as some variations of shots, it will make the production a whole lot more interesting rather than just a single camera fixed shot or zoom in-out.

Re: Record three lavs with 2 audio input camera
 

Another second for the suggestion to rent a mixer. The Sound Devices 302 is purpose-built to do exactly what you're asking for.

Re: Record three lavs with 2 audio input camera
 

I hope you aren't going to run those mics in 'Auto' gain are you?

The best option is hire a soundo to do the job properly... the chances are they will have better mics than you have, they will do it properly, position them correctly, actually monitor them and ride the levels, save you hours in post production, reduce your headaches, less stress for you, make you look good to your client who will recommend you to others which will in return get you more work.
It will be a win for you at a small price.

Re: Record three lavs with 2 audio input camera
 

While I agree with using a mixer, I have done this type of thing a few times when the job changes mid-stream. Like when I get there and "oh, BTW we nned to run 3 mics, not the 1 or 2 we originally said". I have 2 ways to control that set up without resorting to a mixer which again is the right way to do it.
First my receiver is the AT1821 which is a dual channel receiver and I can mix mics 1 and 2 to go to the same side of the reciever which mean I only need to use 1 XLR cable from the receiver to the camera leaving the other XLR input open on my camera so I can then run another mic BUT prior to my having the AT unit (I was an early buyer of it and I don't remember how long ago I go it) I used 2 invidual receivers so I would end up using a "Y" cable. Plug the 2 xlr cables off the individual receivers into the "Y" cable then plug that into the camera then have an open xlr connection on the camera for my 3rd mic.
Ideal? Nope. Workable? Yep. For some run and gun types of works it's the only way and it produces relatively decent audio. Would I do it for critical type work? Not a chance but in a pinch you do what got gotta do using what you got or you go home.

Re: Record three lavs with 2 audio input camera
 

Don,

Thank you for your thoughtful and informative reply to my question.

I followed your example and purchased a 2 into 1 XLR adaptor so that I could run 2 of the mics into one input, and use the second input on the camera for the third mic.

The problem that I have run into is that the sound level on the mics that are run into the Y-cable is much lower than the mic that runs into the second input.

I tried switching the mics around, and the problem was consistent, regardless of the mic (I have all Sennheiser wireless lavs).

Did you have this problem with your Y-cable, and if you did, what was your fix?

Re: Record three lavs with 2 audio input camera
 

I never really had that problem but then I almost always run my audio manually so I could adjust on the fly.
I never ran wired lavs and I don't run an XF series camera but I used the Y cable on a JVC5000U which only had 1 rear XLR (don't ask why) and the levels were very consistant. I ran that on PD150s and PD170s as well with constant levels between the 2 XLRs but again I run mostly manual so I just might have never noticed a difference.
If you're running AGC is there an adjustment in the menu somewhere for the 2 different channels so you can get them close? Also how much difference is there?

Re: Record three lavs with 2 audio input camera
 

'Y' cables are absolutely the wrong way to go. Doing so puts the mics in parallel with each other so they load each other down and screws up the impedance the mic input sees. 'Y's are okay for splitting an output but rarely work well for combining into an input. Better to use a proper combiner such as this one ... http://www.bhphotovideo.com/c/product/351510-REG/Whirlwind_IMCOM_IMCOM_2_to_1_Microphone.html

Re: Record three lavs with 2 audio input camera
 

In my experience (which is certainly "old school" and based on theory rather than just "trial-and-error") it is considered bad practice to connect two (or more) outputs together.

For example, if you connect the left channel and right channel speaker outputs of your power amp together, and then start driving stereo signal through the amp, you are likely to blow the output transistors.

Even in a low-level situation, such as connecting two microphones directly together, or the output of two teceivers directly together, you are likely to run into problems. (Interestingly, this was probably less troublesome 50 years ago, with tube equipment, than it is today with solid state.)

I won't go into all the technical details here (unless someone asks later) but suffice it to say that one aspect of this problem is related to the output impedance of the devices. For example, a mic might have an output impedance of 200 ohms, yet be specified to feed a load impedance of 1000 ohms or greater. So if you connect two mics together, each one is feeding its signal into the other 200 ohm mic (in parallel with the preamp input), an combined impedance which is much lower than the specified 1000 ohm load. That will make the level lower than expected (by several dB) and can also cause unexpected distortion.

So if you're trying to connect two mics, two receiver outputs, etc., you should not use a simple "Y" cable. At the very least you need to know the impedance of the devices in question, and the "mixing" cable should be constructed with correct resistors to prevent the sort of impedance mismatch and mis-loading described above.

Now... can you use a simple "Y" cable? Yes. Will it work somewhat? Probably. Are you likely to have some problems? Yes, definitely, and they are hard to predict without knowing about the specific equipment and situation.

EDIT: Steve H, it looks as if you and I were both thinking and typing the same thoughts at the same time. You beat me to the finish line. ;-)

Re: Record three lavs with 2 audio input camera
 

For a few dollars more than the combiner buy a mixer....

http://www.bhphotovideo.com/c/product/294571-REG/Rolls_MX124_MX124_Portable_4_Channel.html
OK its not a "sound devices" but its way better than a 'Y' cord and far more usable for the future

Re: Record three lavs with 2 audio input camera
 

Let me be clear. A Y cable was not my first choice but there are times and situations that we run into that require hacked together solutions. For instance when one of my best ever corporate clients says to me while on the job doing run and gun coverage of a trade show, "hey I need you to interview these 2 exhibitors and I have someone to interview them" I do what I have to do. Best solution, Nope. Did it work and was the client happy with the result? Yes. Did I like doing it that way? Nope but I don't carry a mixer nor do I hire a audio guy unless it's specified to do so. In run and gun, sometimes things aren't what they are supposed to be.
Anyway for the few times I had to do it, it worked for me.
I suggested it because it's easy to carry an extra cable in the bag and in a pinch it can make the job happen.
I would have hated to tell my client I couldn't do what he asked for even at the last minute and possibly lose a client that put lots and lots of cash in my pocket over the years.

Re: Record three lavs with 2 audio input camera
 

Of course you don't refuse your client. But rather than going with the compromise solution it's far better to have the right tools standing by 'on the truck' so if an unexpected need arises you're prepared. Live by the Boy Scout's motto and always be ready to properly handle the worst case scenario.

Re: Record three lavs with 2 audio input camera
 

Have to say this is the exact reason I picked up a recorder like the Tascam DR-680. I usually only need 1 or 2 channels of audio but I've run into situations where, as Don mentioned, I've gotten to the job and "surprise, we had a last minute third guest panelist". I like to keep all channels separate until I get into post because in those situations with several speakers you sometimes get them talking over each other. And, it always seems they do that at the critical moments.

I'd opt to rent a recorder and capture all audio separately onto 3 discrete channels. Feed the mix out to the camera so you can sink in post. If the recorder you rent can't easily send a feed to the camera use the cameras internal mics to pick up sound to sync in post.

That's at least what I'd do. And, as always, there's a million ways to skin a cat.

Re: Record three lavs with 2 audio input camera
 

Totally agree. I always say "if I bring it I may only have a 10% chance I'll use it. But, if I don't, there will be a 100% chance that I'll need it."

Re: Record three lavs with 2 audio input camera
 

I agree-better to have it and not need it than not have it and die for it. My first Sgt. in basic training taught me that 45 years ago. However, there are some situations where you can have a truckful of gear and still not be able to get to it. Case in point; downtown Chicago. For many of the hotels there are 2 ways to park. Park yourself and IF you're lucky get find a rather expensive parking lot 3 or 4 blocks away OR let them park your car and it's about an hours wages and you still can't get to it because they parked 2 to 3 blocks away.
Again it's not because I wanted to but necessity of the situation dictated. We've all had those moments where you do what it takes even knowing in your heart that it isn't exactly the right thing to do.
Nothing more to say on this one.

Re: Record three lavs with 2 audio input camera
 

In this scenario, instead of trying to juggle 3 lav mics, I would have set up one handheld, and let the interviewer handle the mic like how a news reporter does.

Re: Record three lavs with 2 audio input camera
 

Don, thanks again, you solved my problem.

Each of the two inputs on the XF305 has its own gain control, so I just boosted the gain a little bit on the channel with the two mics and now the levels are all equal. To avoid problems in the field, I will make sure one of the Y mics is on me so I am not asking questions while the talent on the second Y mic is talking.

I will, of course, run some tests before using this in the field, but it seems to work perfectly for my application.

Thanks.

Re: Record three lavs with 2 audio input camera
 

I have a Tascam DR-07 for times like this. Its about the size of a wireless transmitter and you can plug Sennheiser style lavaliers into it. Set the low enough so it doesn't peak. Hit record and hold then sync in post.

Re: Record three lavs with 2 audio input camera
 

If the shoot is a professional paid gig then I would echo what others have said rent or buy a mixer. Test it out before hand to make sure there are no surprises. Even though there are other ways to get around a mixer, I wouldn't put myself at risk. There is little that can be done to fix audio problems in post.

Re: Record three lavs with 2 audio input camera
 

If you don't have a mixer, you might not have enough knowledge to avoid phasing artifacts with multiple mics picking up the same sound, so instead I'd recommend using a separate recorder for the third channel. That way you can fade up only whichever mic is in use for a particular segment.

I just did this yesterday; I usually only record two channels but yesterday I needed two lavs and a boom, so I recorded the extra channel on an h1 recorder. If you're buying a recorder for this purpose and want to stay cheap I'd recommend the DR-05 instead.

Re: Record three lavs with 2 audio input camera
 

What knowledge do I need to avoid phasing artifacts?

Re: Record three lavs with 2 audio input camera
 

The best place to start learning how to avoid phasing (combing) artifacts is understanding the 3:1 rule:

3:1 rule

Re: Record three lavs with 2 audio input camera
 

Thanks, Tom. Great article.

Since the three of us will be wearing wireless lavs, I will be sure to keep us at least three times apart from each other as the distance of the lav to their mouth.

Thanks again.