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Old April 19th, 2004, 07:45 AM   #1
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AT897/DXA-8 Hiss at max. volume...

I recently bought a Beachtek DXA-8 to use with my Audio Technica AT897. The DXA-8 certainly boosts the signal level from the mic, but I've noticed that there is an audible hiss through the earphones when I set the Beachtek up near maximum amplification. Is this normal?

Initially, I detected some really noticeable noise coming from the Beacktek, but discovered that if I turn off the unused right channel and set the Beachtek to mono mode, that noise is eliminated.

The only remaining problem is the hiss. It seems that no combination of preamp gain and camcorder audio gain (in manual mode) can be found to totally eliminate this hiss. It is much noisier than the internal mics.

Anyone have any ideas about this? Could I have gotten a bad preamp?

Bob Reed
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Old April 19th, 2004, 08:46 AM   #2
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What cam are you using? If its a VX2k the headphone circuit is noisy no matter what but you wont hear the hiss on playback through monitors or phones hooked up to your NLE etc.I dont own the DXA-8 yet but am planning on getting it.Bryan Beasleigh did a small review here and liked the unit and did not report any hiss with several different mics and gain settings.
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Old April 19th, 2004, 09:04 AM   #3
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Matt -

I am using it with a Canon GL-2. Although I haven't tried actually recording the audio to tape yet, the hiss is much more noticeable through the headphones when using the preamp than it is with the built-in mic. That's what convinced me that DXA-8 is to blame.
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Old April 19th, 2004, 09:05 AM   #4
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I should also note that everytime I have used the DXA-8, I had it screwed to the bottom of the camera. I will try it tonight with it disconnected from the camera body (it may be picking up electromagnetic noise from the camera).
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Old April 19th, 2004, 09:12 AM   #5
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The key is to set up a realistic recording scenario, with realistic levels, normal micing distances, etc. Record that and capture it to your NLE. Set playback for normal monitoring levels through your editing speakers. Then decide whether you're getting enough gain without additional noise.
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Old April 19th, 2004, 02:01 PM   #6
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If you don't have a mic on channel 2 then there is no reason to switch it on, is there? A mono stting will give you audio on both channels, stereo will separate the right and left channels. Read the manual, it's very clear

As a general rule you should never run any electronic gear at max gain. Where do you have your camera gain set?

The is a grounding switch as well. If you read the manual it will tell you what to do.

To properly test the unit you should actually record audio to tape and play it back on monitors or good quality headphones. I tried this unit with a $1200 mic, a $400 and even a $100 dynamic mic with absolutely no hiss. I also never had to raise the gain past 70% (with a dynamic mic), with condenser mics the gain was around 40-50%

Do you have the camera set for manual or auto gain control?
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Old April 19th, 2004, 06:45 PM   #7
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I just found and read the manual. It's actually very easy and most of the setup is on page 57.

In menu turn audio level ON

Set audio to manual on the slide swictch by the audio level incicators.

Turn the L and R controls to set level (start at 40%)

Turn mic attenuation OFF

All of the above are important.
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Old April 19th, 2004, 09:05 PM   #8
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Bryan - I am not aware of any manual that's 57 pages long. The DXA-8 comes with a two-sided, one page usage guide. That's it.

I am currently set up with the mic attenuation turned off, the mic volume levels on the GL-2 set at about 40% and the mic levels on the DXA-8 set at near 100%. I set it to these levels in order to get -12db vol. levels. Perhaps I can just cut back a bit on the DXA-8 and settle for a bit lower levels.
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Old April 19th, 2004, 09:26 PM   #9
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Or bring the GL2 levels up. The GL2 doesn't suffer from a lousy preamp.I wouldn't run the DXA-8 higher than 75% leave the DXA-8 at 7 0r 7.5 and ride the gain on the camera. The GL2 doesn't have much gain by the sounds of it.



The manual I was referring to was the GL2..

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Old February 15th, 2005, 10:13 PM   #10
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I'm going to buy an AT897, but I was going to buy the SignVideo XLR adapter instead of the Beachtek DXA-8, since it's alot cheaper.

This whole pre-amp thing is scaring me though. Do I NEED the DXA-8 to get audible levels from the AT897 into my GL2, or will the less expensive SignVideo adapter work?

someone please clarify this for me so I don't waste my money on the SignVideo.
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Old February 15th, 2005, 11:02 PM   #11
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The AT897 will drive the GL2's input without an external preamp.
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Old February 16th, 2005, 12:31 PM   #12
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Thanks for the tip.
Now that I know that the SignVideo adapter will work, is there any other good reason to get a more expensive Beachtek adapter instead? I don't really understand the differences between them, other than the fact that the DXA-8 has a pre-amp (that apparently I don't need)

Will I be happy with the SignVideo? Or will I regret not buying a better XLR adapter later?

thanks
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Old February 16th, 2005, 01:16 PM   #13
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There is always equipment that you don't have yet that will allow you to get better audio from more types of situations.

So if you're the type that tends to invest in his hobbies and wants his equipment to grow as his knowledge grows, you will outgrow the SignVideo adaptor. That's because you will want not only phantom power (which the SignVideo may already have, I forget), but also preamps and limiters.

Phantom power allows you more choices in mics, if you didn't already know, preamps help with signal to noise ratio when you have mics with weaker signals, and limiters allow you set your gain high to get good signal to noise ration while automatically preventing the clipping that would result from loud passages when the gain is set high.

The DXA-8 has all three features, but on the other hand you might want to go higher than the DXA-8 and get a true field mixer like the MixPre. I have the DXA-8 and I'm starting to think about the MixPre.

That doesn't necessarily mean you'll regret getting the SignVideo adaptor. It's a great improvement over not having an adaptor, and it will have resale value.
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Old February 16th, 2005, 01:18 PM   #14
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Personally, I would get the BeachTek DXA-6, which provides phantom power for better mics in your future. (For now the AT897 can run on internal battery if you don't get this BeachTek.)
This is still more expensive than the SignVideo unit, and is the best non-amplifying BeachTek. I think it represents better capability for the money, because you can use any mics with it.
If you plan on getting a new camera soon that may have phantom power built in, then the lower cost of a different unit might be a better choice.

The SignVideo unit is supposed to be ok too, but you have to use either dynamic or battery-powered mics with it.

You may also want to consider the Studio1Productions XLR-BP Professional unit. It hooks onto your belt instead of the bottom of the camera. Other than that it's very similar to the SignVideo.

http://www.studio1productions.com/xlr-bp_pro.htm
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Old February 16th, 2005, 01:28 PM   #15
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I really want the adapter to be mounted underneath the camera, so that rules out the studio1 adapter (thanks for the link though).

I think I may go with the DXA-6. I don't think I have a need for a pre-amp right now to justify the extra cost of the DXA-8, but the AT897 would be much more convenient if phantom-powered, and I do have access to several other mics that are phantom powered only (I think), and it would be good to be able to use those mics as well.

Also, this is a little off-topic, but: I am going to be buying the Sennheiser G2 wireless lav kit as well. So, with the GL2's hot shoe taken up by the mic, where would I mount the wireless receiver? I've seen those big two-hot shoe adapters, but they raise the two hot shoes pretty high above the camera, and I don't want anything that big. Is the Senn. G2's receiver small enough to mount under the handle of the GL2? or could I just stick it in my pocket with a cord long enough to run up to the camera?

Thanks
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