Olympus DM-420 Digital Recorder Review

Posted by Jon Peddie on September 2nd 2010 | Discuss
Categories: Hardware Review,

Eyes-free recording—testing the Olympus DM-420 digital recorder

Olympus DM-420 and iphone. (Source: Jon Peddie Research)

I was asked why I wanted to test a digital recorder device when I could record using my mobile phone? My first response was, “well, I am a gadget hound, and I like toys.” I was then challenged by the prospect of carrying around multiple devices when I could do everything I needed with one—the ubiquitous iPhone or some other smartphone. However, just as the iPhone has a passable camera—it’s not a great camera, and therefore, I carry a higher megapixel, higher quality pocket camera that has a flash unit, as well as an ambient light detector—I thought a dedicated digital recording device like the Olympus DM-420 would have higher quality and more reliable recording then the iPhone or any other smart phone—the case of being good enough at a lot of things but not great at any one of them.

This then is a report about testing of the Olympus DM-420 recorder versus the Apple iPhone as a recorder and comparing them to a direct microphone recording and the subsequent transcription of all three using Dragon NaturallySpeaking (version 10.0.)

A four paragraph test document was used as the reading template. I wore the microphone and had the iPhone and DM-420 on the desk in front of me about 35 cm away so all three devices recorded the same speech at the same time.

The control was the microphone input reading of that document. Any mistakes that the microphone input reading made (such as missed or incorrect capitalizations, word and number ambiguities—to two and too, and grammatical differences involving hyphens—2D and 2-D, or my misreading) were not counted as dictation errors.

  • The original document contained 354 words.
  • The Compare function in Word was used to see the differences between the dictated documents and the original.
  • Manually counting the differences between the dictated documents (raw error) revealed:
  • The microphone input document, had five dictation—transcription errors—1.4%.
  • The iPhone recorded document, had twelve dictation—transcription errors—3.4%.
  • The DM-420 document, had fifteen dictation—transcription errors—4.2%.

The Compare function reports Insertions (new or different words than were in the original), and deletions (words missing in the dictated document.) Using the microphone document as the control (which had 29 insertions and 25 deletions) the Compare function reported 39 insertions and 40 deletions for the iPhone, and 41 insertions and 41 deletions for the DM-420 making the percent of error differences:

Dragon NaturallySpeaking can read WAV, MP3, WMA, and DSS files. Therefore the iPhone has the additional productivity cost of having to transcode the file from Apple’s M4A format to a WMA format, and the potential risk of error being introduced due to transcoding. The DM-420 can record and play back in MP3 and WMA formats.

I like the look and feel of the DM-420. It is almost as long as the iPhone, slightly thicker, about two thirds as wide, and weighs about the same. The controls are on the right side, which are convenient, albeit familiar to any previous recorder user, and clearly labeled: play, stop, record.

The iPhone requires you to select the recorder app and then press the red button to start your dictation. It has an good-looking VU meter at the bottom of an icon of a microphone, which makes it an attractive and inviting interface; however, as part of its power saving function, the screen turns off denying you the VU meter and the seconds of recording counter at the top of the screen. This requires you to press the activation button at the bottom of the phone, then slide your finger over the unlock slider to get back to the recorder application to stop the recording.

The DM-420 has a removable micro-SD slot on the left side that allows you to move the files from the recorder to a memory card reader or other device. There is also a mini USB connector at the bottom for transferring files directly from the recorder to the computer.

The iPhone files can only be transferred via the special iPhone connector to USB cable, and then through the use of the iTunes application. The M4A files are not recognizable by Microsoft Windows so you can’t move or delete them using Explorer. However, cut, paste, and move work in the iTunes application so that’s not a major obstacle since anyone who owns an iPhone would have iTunes on his or her computer. However, if the user was on someone else’s machine that didn’t have iTunes there would be no way to do a file transfer (assuming that the other machine had Dragon NaturallySpeaking on it.)

In an empirical test I recorded a presentation at a conference using the iPhone. It ran down the battery in two hours, but did not use all of the iPhone’s internal memory (2GB), most of which is available for recording.

There are better audio recording applications (like iRec) for the iPhone.

With its standard 2GB of SD memory the DM-420 can record up to 34 hours of MP3 audio, depending upon the quality chosen, and up to 533 hours of WMA recording. However with good recording quality MP3 would be 13 hours, and WMA would be 34 hours; which seems more than adequate. And if that’s not enough, obviously a larger memory can be inserted.

Usage model—eyes-free

The Olympus DM-420 will live in my car. It is, like other digital recorders I’ve had, easy to find while driving—the feel is familiar. And I don’t have to take my eyes off the road. Similarly, the controls are convenient to use and can be manipulated without distracting the driver. The iPhone, and other smart phones, require looking at the displays to determine which buttons to push to activate the recording and to stop it. This might be acceptable in many situations, but it is entirely too distracting to consider while driving a car or flying a plane, or in an emergency situation where speed is critical.

Also, DM-420 can be configured with audio feedback informing you of which actions you have selected—that’s a really nice feature for an eyes-free operation.

The unit feels solid, has a nice heft to it, and looks like it could take been dropped a few times without damage. The DM-420 also has small rubber feet on its back, so if you lay it on the desk or some other surface it won’t easily slide off or be pushed around.


For simple note taking, lecture recording, and other general purpose applications not involving automobiles and other concentration-demanding situations, either the Apple iPhone or the Olympus DM-420 would be acceptable. The DM-420 has higher quality audio digitizing and playback (including two very good speakers), very long battery life (up to 51 hours) on two, removable, AAA NiMH rechargeable batteries, and sells for $135.

I like the overall appearance feel and operation of the DM-420. It is a productivity tool for road warriors and commuters, and a general purpose note-taker, and conference recorder.

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