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Old April 5th, 2004, 06:29 PM   #1
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AT897/Canon MA-300 Sound Level

I am using an AT897 with a Canon MA-300 (connected to a GL-2) and I have found that the sound level is lower than with the built-in mic. I was wondering if this is because the AT897 has an output impedance of 200 ohms while the GL-2 has an input impedance of 600 ohms.

I can adjust the audio levels manually, but I was wondering if there is anything I can do to boost the output of the 897?

Bob Reed
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Old April 5th, 2004, 08:26 PM   #2
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The mic has an output impedance of 2000 ohms. The MA-300 in mic mode should be around 150 ohms (600 in line mode).

If it is set up properly, only an external line amp or mixer will get you more gain.
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Old April 5th, 2004, 08:44 PM   #3
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Marty:

According to Audio Technica's specs, the mic has an impedance of 200 ohms, not 2000.

Bob
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Old April 5th, 2004, 10:13 PM   #4
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Regardless of impedance, the output sensitivety of the 897 is 9 mv on battery and 10 on phantom. This isn't very hot, but that not a bad thing.
Your onboard mic is most likely has a higher output and operates on Auto Gain Control which will push the gain on softer passages. loudness has nothing to dpo with quality.

Is this an issue? if you want a higher input you'll need preamplification. I use a Sound Devices Mix Pre and a 302 mixer and input a line level into my camera, but then I'm a fussy old fart.

200 into a 600 ohm rated input is a non event, look at the specs of the 302 mixer. http://www.sounddevices.com/download/guides/302_en.pdf
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Old April 5th, 2004, 10:23 PM   #5
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897 Sound Level

I just purchased the AT 897 and I found the audio to be on the low side. The audio hardly registers on the timeline.
I have an XL1s and I use a Sign Video XLR adapter recommended by a guy at B&H.
Can anyone tell me what this is all about?
I read that the 897 has an excellent pick up patern. How is that posible when you can hardly hear it? Do I need additional gear?
Am I doing something wrong?
I tested it at 12 bit and 16 bit, but it didn't seem to make much oif a difference.
Suggestions, recommendations are greatly appreciated.
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Old April 5th, 2004, 10:45 PM   #6
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The Sign Video, MA300 and BeachTek DXA-4 are all passive input devices. they don't preamplify. They mix, impedance match (low to high) and attenuate.

The AT897 has an output of -41 db or 9 mv, My $1400 schoeps has a similar output and so does the often mentioned Oktava MC012.

The reason the ME66 is so popular isn't due to it's wonderful sound but rather it's high output. (50 mv)

I don't have much experience with the XL1S audio but the person you spoke to at B&H should've known better if there is a potential problem with output levels. People flock to the big box stores to get the perceived deals and often very little actual expertise. The little guy that passes out advice gets shut down for the sake of a few dollars difference.

Do a search on the beach Tek DXA-8, the sound devices MM1 or MP1. The DXA-8 attaches to the camera , supplies phantom, 15 db of gain and has limiters all for $370.

The MP1 has a single channel, 66 db of gain, limiters and phantom for $300. It doesn't attach to the camera and can be attached to your belt or a shoulder strap.

I've had an oportunity to test the DXA-8 and I own 2 Sound devices products. They're all built like a brick crapper.

http://www.beachtek.com/dxa8.html

http://www.dvfreelancer.com/articles/beachtekDXA-8.html

http://www.sounddevices.com/products/index.html

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Old April 6th, 2004, 12:28 AM   #7
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Thanks for the information Brian. The friggin guy from B&H actually recommended the sign video XLR addapter $150 when I purchased the 897. He did not mention the output levels at all.

<<I've had an oportunity to test the DXA-8 and I own 2 Sound devices products. They're all built like a brick crapper.>>
Is brick crapper good or bad? no pun intended.
It retails for $370.
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Old April 6th, 2004, 01:02 AM   #8
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A "brick crapper" is a different way of saying built like a brick sh!thouse, or extremely robust. The Aluminum Chanel used to build the Beach and Sound devices is very thick and ribbed for additional strength

I was really impressed by what Beach Tek did with their unit, its really small for what it does.

They'll be coming out with a low cost, line level mixer soon. I'm trying to get my hands on a prototype.
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Old April 6th, 2004, 05:29 PM   #9
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Thanks for your wisdom and recommendations Bryan.
There is no ifs ands or buts about it, I need a preamp!
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Old April 6th, 2004, 05:52 PM   #10
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Wisdom has nothing to do with it. I just went through the same pain you did only I went first ;-)
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Old April 8th, 2004, 10:08 PM   #11
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First, I stand corrected on the output impedance of the mic. It is 200 ohms. Thank you. I'll point out that a typical mic input impedance is 150 ohms, where a typical lline input impedance is anywhere from 600 to 20,000 ohms.

Second, Bryan is right about the high output level unique to the ME66.

However, the mic preamps typical of this breed of camera are notoriously noisy, with limited gain and dynamic range. This is due mostly to the low voltage power available in them. In fact, even the preamps in the professional Beta SP machines are only adequate at best. Every Sony or Panasonic factory rep I've asked about this replied "we make cameras, not audio gear". (That attitude is confirmed by the mere 16 bits recorded on the DigiBeta cameras!)

Have you heard of the "BBC Mod" gor the VX-2000? It removes the preamp completely from the signal path and gives line level input directly to the D/A convertor.

The only hope you have of recording high quality audio is to use an external preamp /mixer.
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Old April 8th, 2004, 10:49 PM   #12
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I have the BBC Mod . Greg Winter out of Rochester NY did it for me. if you read my writeups on the DXA-8 and the mod you'll get the full story.

This mod is only for anal old farts that are overly picky about their audio. I input my audio directly to the cameras analog to digital converter at line level. This is as good as you can get going through a camera.

Use the links in my previous post.

Meanwhile using a DXA-8 or MP1 to preamplify the sudio in will let you operate with the internal preamps at about 20-25% gain. This doesn't make them work too awfully hard and you get no audible hiss.
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