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Audio preamp for Cinema Camera confusion

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Anthony Spark
Audio preamp for Cinema Camera confusion
on Mar 16, 2016 at 6:37:28 am

Hi there.

I have the oportunity to buy a BeachTek DXA-8 camera mic pre amp at a great price.

Would this work well with my Blackmagic Cinema camera? Has anyone had any experience with it?

Here are some specs:



BeachTek DXA-8 - Ultimate Adapter

The ultimate XLR Adapter for DV camcorders. Two channels with preamps, limiters and phantom power

The DXA-8 Ultimate Adapter is a superb front end for DV camcorders. Low noise preamps provide clean, powerful audio levels from virtually any microphone and the output level is preset to the sweet spot for the best signal-to-noise ratio. The no fuss limiters eliminate distortion caused by overly hot inputs for great sound every time. Easy to set up - only requires the adjustment of one gain control for each channel. Limit indicating LED's ensure proper gain setting. Dual 48 volt phantom power for professional microphones. One sweet package!


Features


• Dual no fuss limiters with LED indicators

• Dual Infinitely adjustable gain

• Dual switchable 48 volt phantom power

• Dual XLR balanced inputs

• One unbalanced mini-jack input

• Transformer isolated inputs and outputs

• Uses one 9 volt battery

• LED battery power indicator

• Sturdy extruded aluminum chassis

• Easily mounts to camera and tripod

• Extremely easy to set up and use

• Superb Sound

Specifications

Gain:

Adjustable from -10 dB to +15 dB


Frequency response:

20 Hz to 20 KHz, +/-3 dB (limiter on)

Output noise level:

less than -80 dBu

Input level before clipping:

+1.5 dBu (min gain with limiter on)

-27 dBu (max gain with limiter on)


Maximum output level :

-30 dBu (limiter off)

-36 dBu (limiter on)


Phantom Power:

Dual regulated 48 volt power supplies

Current to 14 mA (direct short)


Battery type / duration:

One standard 9 volt alkaline battery

10 hours typical (no phantom)

LED battery indicator


Current draw:

35 mA typical (no phantom)


Case:

Powder coated aluminum


Dimensions:

5.25" L x 3.5" W x 1.25" H

Weight:
16 oz.


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Brian Reynolds
Re: Audio preamp for Cinema Camera confusion
on Mar 16, 2016 at 9:26:04 am

In a few words 'DONT BOTHER', Yes it might be a preamp but the output of the BeachTeck is on a 3.5mm stereo jack and far from a pro level.
You would need to get an adaptor made up from that tiny jack to 2x 6.5mm plugs to go into the BlackMagic....Even then the connections in that adaptor would be unbalanced and could cause possible problems.

Audio monitoring is also another problem, you need to be able to monitor what is coming out of your mixer / preamp AND with a flick of a switch you need to be able to monitor the output of the camera.

Starting out with that setup you would struggle and it would soon be replaced with a better mixer. Save your money.

Sorry to bust your dreams.

'Celebrating 40 years of Broadcasting Audio....
Started with Magnetic stripe and Sprocket holes to now Gigabytes and Touch Screen Mixing Consoles'......


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Anthony Park
Re: Audio preamp for Cinema Camera confusion
on Mar 16, 2016 at 9:41:14 am

Thanks Brian

Is the 3.5 really unbalanced? Yes I would have to make leads up. I guess I would monitor from the Cinema camera headphone out. Am I thinking correctly. I do appreciate your advice and am thinking of pulling the plug on this purchase.It's only $90.


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Richard Crowley
Re: Audio preamp for Cinema Camera confusion
on Mar 16, 2016 at 2:56:22 pm

Beachtek has a web page explaining why their products (specifically their DXA-BMD model) improve audio recording on a Blackmagic Cinema Camera (BCC). But apparently they don't make the DXA-BMD model any more as Beachtek products come and go like butterflies. They are there for a moment and gone the next and you didn't even get to snap a photo of it.
http://beachtek.com/using-mics-blackmagic-cinema-camera/

They make somewhat convincing arguments why a Beachtek (or other brand) converter would be useful with the BCC.
1) The BCC has oddball 1/4 inch input connectors instead of proper XLR.
2) The BCC does NOT provide phantom power for most professional mics.
3) The BCC may or may not have useful audio metering depending on firmware.
Of course, the DXA doesn't provide metering, either, so that is a washout.

Indeed the DXA is designed to be used with pathetic DSLR cameras with 3.5mm UNBALANCED stereo mic inputs. Not exactly a good interface with the BCC, so you will need an adapter like Hosa YMP-434. Indeed that is the adapter cable shown in Beachtek's photos.
http://hosatech.com/product/ymp-434/

That Beachtek DXA would at least provide XLR and phantom power. Whether that is worth $90 is something only you can decide. IMHO, the DXA isn't a very good fit for the BCC.

It isn't clear from your response whether you are wanting to buy this DXA or not. "Pull the plug" typically implies that you are NOT going through with the plans, while "pull the trigger" implies that you ARE going through with it.


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Anthony Park
Re: Audio preamp for Cinema Camera confusion
on Mar 16, 2016 at 9:49:24 pm

Thanks Richard

I just got the original manual online. It says the output although 3.5mm is unbalanced. Here is a excerpt:

Features

Inputs
• Two transformer balanced XLR
• One unbalanced mini-jack

Output
• Transformer isolated, unbalanced with attached shielded
cable and stereo gold plated mini-plug connector
• Selectable MONO or STEREO

Preamplifier
• Dual low noise preamps to boost volume of low output microphones
• Adjustable gain from -10 dB to + 15 dB
• 20 Hz to 20 KHz audio bandwidth

Limiter
• Independently switchable fast acting limiters make the output virtually “unclipable”.
• Indicating LED’s ensure proper limiter operation

Phantom power
• Dual switchable 48 volt phantom power for condenser microphones

Power
• Easily replaceable 9 volt battery
• LED battery indicator


I also got a message from the Product support at Beachtek and he made a comment on the old DXA-8:


The preamps in the BMCC are better than the old DXA-8 so you are simply adding noise. A passive adapter would give you better results. However, an active adapter like the DXA-SLR ULTRA with 30dB of gain and truly low noise preamps would give you by far the best results. The limiters in the old DXA-8 worked very well, but the preamps pale in comparison to our newer adapters.

I may be looking at the new Beachtek now.There doesn't seem to be many options out there in this 4-5 hundred dollar price range.


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Richard Crowley
Re: Audio preamp for Cinema Camera confusion
on Mar 17, 2016 at 2:50:33 am
Last Edited By Richard Crowley on Mar 17, 2016 at 2:52:10 am

Depending on how you are shooting, a proper audio mixer may be a better use of your budget than a little adapter gadget on the camera. If I were spending $500 I would MUCH rather get a nice proper mixer than a little Beachtek gadget. For example:

http://soundexcellence.com/eng-44a.html

I have one of these and I like it very much.


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Anthony Park
Re: Audio preamp for Cinema Camera confusion
on Mar 17, 2016 at 3:58:26 am

Does this have balanced inputs/output?


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Richard Crowley
Re: Audio preamp for Cinema Camera confusion
on Mar 17, 2016 at 7:53:59 pm

Yes, the ENG-44 has REAL balanced outputs.


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Anthony Park
Re: Audio preamp for Cinema Camera confusion
on Mar 17, 2016 at 10:01:33 pm

I like this device.

Is this an active preamp versus passive? I am trying to figure out how I can make it riggy so I can mount it to my rig. It's quite big, understandably but it needs to be near my camera. I guess that is why people go for smaller devices for portability.


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Richard Crowley
Re: Audio preamp for Cinema Camera confusion
on Mar 18, 2016 at 1:29:37 am

It is active. It requires batteries.


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