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Zoom H2 Audio Dropouts

Tuesday, August 26th, 2008 | by


I bought a Zoom H2 handheld flash recorder for interviewing. I picked the H2 because the form factor was appealing — it’s small — and for its lack of moving parts (hello mini-disc!). The reviews I read raved about the feature set, and although users were generally positive about the sound quality, I wasn’t shopping for a high-fidelity field recorder so much as a simple interviewing tool.

And it has four microphones! They might as well have put my name on the case.

As an interviewing tool, the H2 works wonderfully. Without touching the manual, I was able to set it to record 192 kHz MP3s with a “vocal” compression patch inline, and it made a couple extremely clean interviews for me with no fuss and no discernable noise. The LCD display of the input level was very helpful as a sanity check that it was still working throughout the interview.

My old interviewing rig was a laptop: I was using the built-in mic on a Macbook Pro. Designed for sources two feet away rather than 10 feet away, it was barely adequate, and not very portable, so it got left behind when, during an interview, we’d wander around studios to look at gear.

For a while I also carried my old Walkman-size cassette recorder with a little external mic, as a backup recording device. Despite being ancient technology, it worked really well, and it let me open interviews with a wisecrack about how the laptop was recording but “I just can’t get enough of that analog sound!”

No, nobody ever laughed.

The other day I had an opportunity to record a band rehearsal with the H2. Not wishing to futz around with it, I simply turned it on, pressed the red button, and set it in the middle of the room.

The sound quality was decent. My goal was to capture the jam, not to make a live CD, and for this it was ideal. It created a mixed, ready-to-play MP3 file that I could easily share with the other band members.

The only problem? Audio dropouts. I made three recordings of 10-20 minutes apiece. Each track contains 2-3 audio dropouts. They last from 1 to 1.5 seconds each. Hear two of them here:

The H2 had all four mics active, and was set to record a stereo MP3 at 192 kbps, with the COMP2 compression patch still inline. I was using the supplied 512 MB SD card, and version 1.30 of the OS.

The designers of the H2 foresaw the potential for dropout problems. Page 62 of the manual is dedicated to this topic.

H2 Manual

Depending on the combination of operation mode and recording mode, data transfer to the SD card during recording may momentarily not be able to keep up with the data stream, leading to a brief sound dropout. When this occurs, the indication “Data write Error” is shown on the display during recording and after the recording is finished.

I didn’t notice any such warning on the H2 during rehearsal, but I can’t be certain it wasn’t there. Unfortunately I also can’t check the H2’s marking system, which bookmarks points in the audio stream where dropouts occurred, because I’ve already purged the files.

However, the behavior here is not what is predicted by the H2 manual. A chart in the manual suggests that dropouts only occur under “heavy processing load,” such as when recording 24 bit, 96 kHz stereo WAV files, or 4-track 24-bit 48 kHz WAV files. Either way, that’s something like 25 times as much data as I was recording (based on the H2 SD-card capacity chart at Oreilly.com).

Let’s do the math. I used Bias’ Peak Pro software to upsample and convert a 10-second song sample to two formats, for this size comparison:

  • 10 seconds of 24-bit, 96-kHz WAV audio consumes 5625 KB of space
  • a 192 kbps, 16-bit MP3 of the same audio consumes only 240KB

That’s a 23x difference in filesize, and therefore a 23x difference in data bandwidth.

So, whatever problem this was was not likely to be due to the SD card’s throughput rate; if the card is supposed to be capable of 23x more data throughput, why would it be choking on my puny MP3s? I speculate that the problem was actually CPU overload.

I’ve since ordered a faster SD card, not so much because I think it will matter, but because I needed a bigger one anyway. I’ve upgraded the OS to 1.4, which also should have no effect. And next time I’ll disable the compressor patch. Given that none of these changes is likely to fix the problem, though, I suspect the problem will continue. (Maybe I need to record WAV files instead?)

I will post an update after our next rehearsal. Based on the comment from Stefano (see below), I did a quick test: recorded 5 minutes of music twice, once with the compression filter enabled and once without. All other settings were identical: 4-mic, 2-channel surround mode, 192 kHz MP3. Both tests generated dropouts. Neither test generated warning messages. Maybe this unit is defective.

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Posted in Reviews | 6 Comments »




6 Responses to “Zoom H2 Audio Dropouts”

  1. stef

    August 28th, 2008 at 2:20 am

    Hello!
    I use this recorder many many times with a normal SD card in MP3 or high quality WAV 24/48 and I never had any dropouts problem. I know a friend of mine who has done with 3 H2 many hours of interviews with no drop outs BUT in all cases we never used the effects processor like compression so perhaps this is the cause of the problem. My advise is to switch off any effects function. They are also bad qualities. It is really better to take the time to verify your sound level regurlaly.
    Sorry if my english is not perfect 😉
    Sincerely,
    stefano

  2. Dave

    September 5th, 2008 at 9:30 am

    I’m having the same problem with the wav files.

    I’m also not able to burn the files to a cd with Media Player on XP or Vista. It says it can’t figure out how long the files are so it can’t burn them.

  3. PMDonald

    September 23rd, 2008 at 7:01 am

    I have an H2 as well, and love it. I have read about this problem on the net and have heard that using a better SD card solves the problem.

  4. stephen

    March 3rd, 2009 at 7:02 pm

    i haven’t had any problem with mine. i use a class 6 card and it is 4gb. the sd card site ( http://www.sdcard.org/developers/tech/speed_class/ ) alluded to a possible problem if running the card close to capacity, dropouts due to fragmentation, perhaps it is the case with yours?

  5. David

    November 13th, 2009 at 1:55 pm

    H2 recording line input has tiny gaps which come out like bad splices. There are no dropouts but missing segments where the stream is spliced. It is quite audible and ruinous of otherwise fine recordings. Using several different Sandisk Class 4 SDHC cards. Maybe the cards are bad.

  6. webaschtl

    December 7th, 2015 at 12:55 pm

    Hi there,

    plenty of years later … using a H4n, connected directly to the mixer in an auditorium, only speech, therefore recording as mp3 … fortunately in addition to the video recording, because there are such dropouts, too! And sometimes without silence, just 1-2 seconds missing :(

    Is this just a problem with the used sc card?

    Unbelievable! :(

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