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Old June 29th, 2009, 09:52 AM   #1
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Zoom H4 Bass

I just got back from recording a dance recital and was the first time I used the Zoom H4 portable digital recorder as another audio source to my video camera. It sounded very good except in parts where there was a lot of bass, it was distorted.

I pretty sure in many of these sections it wasn't too loud although the wave form looks chopped. http://i39.tinypic.com/24dk8k4.gif

The H4 was located on the side of the stage but not in front a speaker while my camera was at the back. I was also using the H4 internal mic and lowered the levels down to 80 but was left unattended so I can't verify if the levels were too high but I don't think that was the problem.
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Last edited by Pete Cofrancesco; June 29th, 2009 at 10:45 AM.
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Old June 29th, 2009, 11:08 AM   #2
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What setting was the sensitivity switch on the side of the H4? The bass energy may have been overloading if the sensitivity switch wasn't set low enough. The switch has a pretty wide range in its 3 positions and often what you really need is a sensitivity that falls in between 2 of the settings. So it can often be difficult to hit the sweet spot with the H4 when using the built-in mics, especially since you couldn't monitor the unit during these bass-heavy passages.
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Old June 29th, 2009, 11:18 AM   #3
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The gain switch on the side was set to "high". But during dress rehearsal I did a couple of tests and set the levels in the menu. So whats the difference between the gain switch and the levels menu?

Its not the end of the world because for the distorted sections I can switch to the camera mic. I just wanted to understand what was going on and how to avoid it in the future. I could set the levels more conservatively but wanted to make sure it wasn't something else like the internal mics can't handle the heavy bass or that it's overloading the preamp in the recorder.
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Old June 29th, 2009, 03:54 PM   #4
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It's overloading the preamps because the gain switch is set to "high".

The signal path is a little quirky in that recorder (the original H4). Really, you *must* get into the right range with the gain switches for the content. "High" is useful for dialog, "Medium" for most music, "Low" for most loud music. At least that's how I think of it, your mileage may vary.

The recording volume is fairly useless if the gain switches are incorrectly set.
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Old June 30th, 2009, 08:38 AM   #5
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Quote:
Originally Posted by Seth Bloombaum View Post
It's overloading the preamps because the gain switch is set to "high".

The signal path is a little quirky in that recorder (the original H4). Really, you *must* get into the right range with the gain switches for the content. "High" is useful for dialog, "Medium" for most music, "Low" for most loud music. At least that's how I think of it, your mileage may vary.

The recording volume is fairly useless if the gain switches are incorrectly set.
Thanks your right. I replayed it back on the player and realized that the Levels indicator is misleading. The bars don't go all the way to zero, they stop at about -3db and that's the maximum where you hear its distorted. I've seen better level indicators that either turn red or display a block at the end to indicate that levels are too high. The distortion is from the gain being set too high and not that the preamp being overloaded. The sound booth must have raised the volume after the dress rehearsal or I didn't hear the distortion in the bass with my headphones because it was so loud.
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Old June 30th, 2009, 11:18 AM   #6
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Setting the side-mounted gain switch too high does overload the preamp.
You won't have a visual representation of that on the level meters. So really they aren't misleading, they are properly showing the level of the recorded signal. It's just the signal is already damaged by the time it gets to the level controls and visual meters.
Listening with isolating headphones or in-ear phones, or running a monitor cable into an isolated room nearby may be necessary for clean monitoring in a loud environment.
I can certainly agree with Seth based on my H4. The high setting is suitable for spoken word even at a distance. If it was loud enough for difficulty in monitoring with headphones, medium or low gain would be much more suitable.
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Old June 30th, 2009, 07:38 PM   #7
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Originally Posted by Jay Massengill View Post
Setting the side-mounted gain switch too high does overload the preamp.
You won't have a visual representation of that on the level meters. So really they aren't misleading, they are properly showing the level of the recorded signal. It's just the signal is already damaged by the time it gets to the level controls and visual meters.
Listening with isolating headphones or in-ear phones, or running a monitor cable into an isolated room nearby may be necessary for clean monitoring in a loud environment.
I can certainly agree with Seth based on my H4. The high setting is suitable for spoken word even at a distance. If it was loud enough for difficulty in monitoring with headphones, medium or low gain would be much more suitable.
Ok your right about it being overloaded at the preamp, but why didn't they explain in the manual that the side gain button is for the preamp? It's presented as a quick way to get at the levels without going into the menu. I also read they removed it in the H4N, if that is true how would one prevent overload of the preamp?

I wasn't imagining the issue of the visual level meter. I found out something you might not be aware of. When you reduce the levels, the visual meter no longer goes up to 0db. So at 85 the meter won't go past -3db which gives you a false sense that hey I'm at -3db can't be distorted because it hasn't touched 0db.

This is the first audio recorder I've used so I don't know if they all work that way but I think its a bad design. Sure its optimal to judge based on what you hear with headphones but often there are situations where you can't. Seems odd there are no visual warnings for overload/distortion/clipping before and after the preamp.

I know you'll say you need a dedicated audio person monitoring it but in the real world for productions on a budget there often isn't and this device's target audience is pro-sumer not for a dedicated sound pro. They really should have an auto dummy mode for unattended recordings just like they do for video cameras.
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