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Joe Riggs

Getting an audio reference track in the ALEXA

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Hi,

I'd like to get a scratch track into the Arri Alexa.

It has a 5 pin xlr connector and I thought it would be as simple as getting a 5 pin to 3 pin adapter and then plugging in a mic.

However, I was told because it is a line level input that it is more complicated than that?

This is what the manual says "2-channel analog line-level audio can be fed to the camera via the 5-pin
XLR connector located at the front of the camera on the camera-right side."

I'm not an audio guy, so I'm not sure what is needed, but all I want is a reference track in the footage even if it's not the greatest quality.

Thanks

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Alexa is line level input only.  A mic needs a preamp to get the signal up a level the Alexa can record.  The usual way of doing this is a via a portable mixer.   Get the rental house to help you with this, it isn't complicated.

 

philp

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Smallest pro quality probably SD MixPre.  But you will not have the (questionable) benefit of AGC on the audio that most cameras that have mic inputs have for on board mic situations.  However if you set your levels well the sound will be very good.  As I said, if you are renting this camera then the rental house should help you solve this.  

 

philp

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Hey guys,

 

Anyway to do it without a mixer?

 

Could this setup work

 

http://woodencamera.com/A-Box-ARRI-Alexa.html

 

and

 

http://www.bhphotovideo.com/c/product/73100-REG/Sennheiser_ME66_K6_COMBO_ME66_K6_Super_Cardioid_Mic.html

 

The k6 is a preamp right?

 

Joe - Neither will help with your needs.  The Wooden boxes just break out to 3-pin connectors and the preamp you listed works with a microphone capsule to then send out a mic level signal. 

 

The advice you've been given here is good.  Talk to your rental house about a mixer appropriate for the job.  The MixPre would be my first thought, also.  If you prefer to buy, used MixPres are going for really reasonable prices now since they've been superseded by the MixPre-D (which you don't really need).  You would also need a cable to go from the MixPre to the 5-pin line-level input of the Alexa.

 

No doubt many of us are curious how it is that you can afford to use an excellent high end camera such as the Alexa, but you can't afford to hire a professional sound person so your sound is up to the standards of your picture? 

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John,

 

Thank you and trust me if it was up to me I'd hire the best sound sound mixer, but I'm not the producer or director.  

 

Just to reiterate, I can't use the Me66/k6 mic and boost the audio levels within the camera (even if the track is low, it would still be helpful to me)?

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...

Just to reiterate, I can't use the Me66/k6 mic and boost the audio levels within the camera (even if the track is low, it would still be helpful to me)?

 

Just to reiterate -- no.

 

A microphone typically puts out less than 1/100th of the signal level that you need.

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Just to reiterate, I can't use the Me66/k6 mic and boost the audio levels within the camera (even if the track is low, it would still be helpful to me)?

 

No, no preamp or phantom power in the Alexa that I'm aware of (pages 64-65 in the manual). You have to go through a mixer or recorder first, then feed that output to the Alexa. 

 

I generally go through a wireless hop out of my recorder/mixer, then use a wireless receiver attached to the camera to provide it a mono scratch track. 

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The K6 is not a preamp but a power supply for the microphone. Providing ONLY a mic level signal out.

It contains a preamp that converts the high impedance of the condenser element to a low impedance microphone-level output. With a condenser such as the Schoeps Collete series, the CMC also contains a power supply that furnishes a polarizing voltage to the capsule.

Electret condenser mics (such as the one mentioned) have a pre-polarized capsule. Electrets typically don't perform to the standards of a mic that needs a polarizing voltage, but they are relatively inexpensive to produce, in part because they don't need a polarizing power supply along with the impedance-converting preamp that they do need.

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John,

Thank you and trust me if it was up to me I'd hire the best sound sound mixer, but I'm not the producer or director.

Just to reiterate, I can't use the Me66/k6 mic and boost the audio levels within the camera (even if the track is low, it would still be helpful to me)?

The K6 module, when you use the AA battery, replaces the need for a phantom power source, but still only outputs mic level. There are a few cameras out there that take a mic level input, but don't have phantom power capabilities. That's where the ME66/K6 is useful.

Maybe a Sound Devices MM1 is the cheapest option. The Alexa is really intended for professional projects that are either MOS, or have a sound person.

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Would a simple route be a wireless lav from the mixer to the Alexa, that way you don't have to be tethered?

You mean a wireless link between mixer output and Alexa input? Yes. That would be simple, and if a quality wireless system is used, levels are correct, and mic placement is good, it'll sound nice too.

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Right, but is that done with just a lav like a G3?

 

Is that what a "wireless hop" is?

It could be, if you set the output of the G3 receiver (on the camera) to line level output.  But there is no good way to ride gain on the camera while rolling, you'd have to set a level and hope for the best.  On this forum, what is meant by "camera hop" is a wireless link between the sound person's equipment (mixer/recorder/wireless receivers etc) and the audio input of a camera, where the camera input level and the audio system output levels have been matched (via setting levels with a test tone).

 

philp

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Right, but is that done with just a lav like a G3?

 

Is that what a "wireless hop" is?

I think there is some misconception of what a "lav" is here.

A lav is short for lavalier, which is a type of microphone, which can be connected straight to a mixer (via XLR, commonly referred to as 'wired lavs') or to a wireless system (such as the Sennheiser G3 evolution series, commonly referred to as radio mics, wireless lavs, etc.)

The G3 is not a high end wireless system, and as such is not really used as a wireless link to camera (commonly known as camera link or camera hop), instead, it is more commonly used as a reference or scratch track for camera when used in such situations.

Hope that helps clarify a bit further.

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riggs: " simple route be a wireless lav from the mixer to the Alexa,...Right, but is that done with just a lav like a G3? "

I was going to suggest lowering your rate, but Jose and Philip have tutored you...

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All I'm looking for is a scratch track.

 

Does the 5pin to 3 pin cable have to be at a right angle or will this work?

 

http://www.bhphotovideo.com/c/product/407854-REG/Hosa_Technology_DMX_106_5_Pin_XLR_Male_to.html

 

 

 

This is was mentioned to as a possible solution to not have ot be tethered.

 

http://www.bhphotovideo.com/c/product/747361-REG/Nady_DMP_2_DMP_2_Compact_Microphone.html

 

It has a Gain Range of 50dB

 

Would that work?

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All I'm looking for is a scratch track.  Does the 5pin to 3 pin cable have to be at a right angle or will this work?

 

I would talk to the guys at Wilcox (818.504.0507) or Audio Department (818.566.6526) about making a custom right-angle 5-pin XLR-F to two breakout XLR-3 Male connectors. If you can keep the cable low-profile, that seems to help the camera department somewhat. It's not an expensive cable, maybe $50-$60. 

 

The Nady preamp you mention is not what I'd consider a professional product, and you won't need a preamp if you're coming from a wireless hop into an Alexa. The camera department will kill you if you have a hard-wired connection (and understandably so). 

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