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Old April 12th, 2008, 12:09 PM   #1
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XH A1 & ZOOM H4: mixer or preamp? hdv compression?

I'm shooting a short film with my A1 and want to capture sound on my zoom h4 using external mics into the xlrs. Sound will be edited in soundtrack pro and outputted to blu-ray (through toast maybe? if apple hasn't patched blu-ray support into compressor by then.) I'm completely new to sound stuff so forgive me if the answer is obvious...

1) Since the h4 has a built in low-cut filter and a limiter (though I can't find in the manual at what threshold it kicks in at) as well as individual input level adjustments; is there any real advantage to running the mics through a mixer first as opposed to just a preamp like an ad-20 etc?

2) Also, the h4 can record at 96khz 24bit but I know hdv significantly compresses the audio to 384kbps. I don't really fully understand how khz translates kbps - but would there be any point recording at this high a quality or can hdv only support 48khz 16 bit like the A1 records at?

As always, thanks for the help!
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Old April 12th, 2008, 12:46 PM   #2
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1. The main advantages of the mixer are - it sounds better, and it's easier to mix on. The preamps in the Zoom will be noisy and won't sound very good. Also, mixers are made for controlling levels and a recorder like the H4 makes this a little more difficult. You can get a good result without one, but a mixer will make your life a lot easier.

2. You don't have to worry about the sound recorded onto camera because you're going to an external recorder. However I don't think there's any point to recording at 96khz/24 bit. I don't know how noisy the recordings will be but "film standard" right now is 48khz/24 bit. If they are noisy, the difference between that and 44.1/16 is not going to be great. Also, there are advantages, like the files taking up much less room.

Your question about how Khz translates to kbps is a good one. Usually uncompressed formats are measured in kilohertz because they are expected to store everything they record with equal precision across the frequency range. MP3 and other compressed formats "emphasize" certain ranges of the sound, depending on how compressed they are; MP3s are still recorded at 48khz or 44.1 (etc), but they are measured in kbps because the adjustable file size determines the amount of information stored.

Awkward wording I know, hope that helps a little! Best of luck on your short.
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Old April 12th, 2008, 01:16 PM   #3
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thanks for the info abe -

you say the mixer "will sound better" - do you mean just because it has better preamps? wouldn't running my mics into a separate preamp w/o mixer before the zoom solve this?

My zoom manual says "a recording level of 100 will result in unity gain (no amplification)" [on a scale of 1-127]. Wouldn't this bypass the internal preamps of the zoom leaving the audio to be effected only by the higher quality external preamp? Or will the zoom's preamps always have a negative effect on the audio?
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Old April 12th, 2008, 01:43 PM   #4
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Quote:
Originally Posted by Cal Bickford View Post
My zoom manual says "a recording level of 100 will result in unity gain (no amplification)" [on a scale of 1-127]. Wouldn't this bypass the internal preamps of the zoom leaving the audio to be effected only by the higher quality external preamp? Or will the zoom's preamps always have a negative effect on the audio?
The H4 is not optimal for recording with XLR mics. For one thing, the controls on the little screen are nowhere near as convenient as real rotary gain controls on a mixer, that you will need to be adjusting during recording. Second the preamps are noisy. At any setting from 1-127, the Zoom preamp will not be bypassed. At a gain of 100 (unity), you may find the recorded signal from many external mics to be rather low (of course this depends on the specific mic involved, as some put out a hot signal.) If you bring the gain up to 127, the preamp in the H4 becomes noisy. If you are serious about sound, I would recommend going another route. Others have used a quality preamp and sent line in to the A1 with satisfactory results, but of course HDV sound is very compressed. Do a search of this forum for more information. (However, in my tests of the H4 and my HV20, I was able to get better voice recordings on the HV20 going through an external mixer.) Of course if you are going to process the sound a lot, going with a good quality external recorder that records 24 bit 48 kHz uncompressed would be the best way to go.

Where I think the H4 shines is as a field recorder to pick up ambient sounds with its internal mics. You do have to be aware that handling noise in that situation can be problematic, but if you mount it on a stand, set it, and then don't touch, you can get ok results.
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Old April 12th, 2008, 01:45 PM   #5
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No, you're right - using the external preamp will bypass the Zoom's pres and give you better sound. The benefit of the mixer then is just better control over levels, looks like the pots on the AD20 are pretty small.
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Old April 12th, 2008, 04:40 PM   #6
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David, when you tested the h4 were you running the signal through a mixer first too?
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Old April 12th, 2008, 06:03 PM   #7
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Quote:
Originally Posted by Cal Bickford View Post
David, when you tested the h4 were you running the signal through a mixer first too?
Cal,

no I was not. If you send the signal through a mixer with decent preamps, then you can use less gain on the H4, and get a better recording on it, and not have to fiddle with the H4's controls. That might be something to try in your situation. However, a mixer with very good quality preamps is not inexpensive.
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