Field Report: Olympus DM-620

November 1, 2011


Olympus DM-620

When trying to decide on a digital recorder you may feel overwhelmed with the selection available. There are so many brands, styles and microphone architectures, that you have to first decide what you want to do with your portable recorder. The Olympus DM-620 may be your be all end all decision. The 620 is flexible and expandable for nearly any future use.

First, the most unique feature of this recorder is the Tresmic 3 microphone system. Tresmic captures a wider stereo sound with two mics mounted left and right of the top of the recorder and a third mic in the middle. The middle mic is omnidirectional and can be adjusted to affect the width of the stereo pickup, from 180 degrees to about 45 degrees. The center omni-directional mic captures lower bass ranges with stunning clarity.

The center mic can be turned off, but the added ambiance of the center mic makes the recordings on this device pop. Take this recorder to a meeting hall and catch the speaker with the mic zoomed in, or questions from the audience using the full 180 degrees of coverage. Full coverage is also good for capturing surrounding noise without overpowering an interview.

Performance at a glance
• Mic and headphone jacks
• Built-in speaker
• Frequency response 20Hz-20kHz (center mic on) or 70Hz-20kHz (center mic off)
• 4GB built-in memory. Up to 32GB memory with microSD/SDHC
• Records linear PCM (WAV), MP3 and WMA

Mic sensitivity can be adjusted on the fly by using the left and right buttons on the front of the recorder. These mics can be very sensitive and cover a large distance. The recorder comes with five preset recording scenes and three more user designed scenes for your recording uses: lecture, conference, meeting, dictation and music. Lecture, for the lecture hall focuses on the center speaker, the mic sensitivity is high and the zoom mic is picking up more forward sound. Conference setting still has high sensitivity, but the zoom mic is collecting a full 180-degree range of sound. Meeting is a middle sensitivity setting and dictation has low sensitivity. For music, sensitivity is set by the user. All of these settings can be adjusted and then saved if the settings are going to be used again.

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In the field

Recording a live concert with low mic sensitivity was clear and crisp while keeping good bass levels creating a full spectrum sound. No sound loss was ever experienced using this recorder for one-on-one interviews, or city hall meetings. In fact listening to the recordings with headphones puts you back into the place where the recording was made keeping all sound natural.

Tresmic 3 captures a wider stereo sound with two mics mounted left and right and a third mic in the middle.

Tresmic 3 captures a wider stereo sound with two mics mounted left and right and a third mic in the middle.


The 4GB of built-in memory, microSD card slot and three recording formats allow you to record a lot of audio. More than 5 hours of linear PCM recording time, more than 131 hours of MP3 recording time and more than 1,000 hours of WMA recording time are available.

Other features include a built-in speaker, standard mini plug headphone jack, a connection for a remote device (sold separately), USB port for charging the included NiMH batteries and transferring files, and a microSD slot for up to 32GB of external storage.

The recorder can be used with either the included NiMH rechargeables or any two AAA Alkaline batteries. Charging time is approximately three hours from dead to full charge for about 19 hours of use time. Using alkaline batteries can boost that up to about 25 hours, but you of course lose the rechargeable aspect. The DM-620 can be recharged through a computer with any USB 2.0 connection or in a USB power station.

Back on the sensitivity of the mics; I was toying around with the mic before taking it out to run its field tests and at the same time I was watching one of the many ghost-hunting shows on television. I looked at the DM-620 and thought, this device is way better than any of the recorders those guys use for their EVPs. So this sparked an idea, I then contacted a friend who is in a local paranormal investigators group and said, "Hey, take me ghost hunting, I've got the coolest recorder and want to test it."

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So we went ghost hunting at an abandoned church where they claim lots of activity takes place. They wanted to do what they call an EVP session (EVP = Electronic Voice Phenomenon, which is claimed to record the voices of paranormal entities). This session involved leaving recorders in the building with no one around and going back to listen. They left their recorder in first. We then went outside and I was checking out the features on the recorder deciding on what settings I wanted to use, I decided to fully take advantage of the center mic, and made the setting for the wide stereo recording, I then decided to set the sensitivity quite high. We collected the previous recorder and I set the Olympus DM-620 to record and we left it in the church. While outside, we analyzed the audio on the first recorder. After collecting the DM-620 we listened to what was captured. We were amazed at the full range of sounds captured. The sound was an exact duplicate of what was heard within, full thumps of our footsteps, crickets outside and then we were amazed at the sound of a ghost, mocking us. OK actually no ghosts found, but this recorder was so good that it not only captured the sounds inside the chapel, but also picked up the sounds outside the building. The recording was of us outside the building in a parking lot 20' away listening to the previous recording. So if you want range, the DM-620 has it. Not so sure about ghosts. I'll leave that to the professional ghost hunters, and stick with being a broadcaster.


Wilson is an announcer, producer, webmaster and promotions guy at WAKO-AM/FM, Lawrenceville, IL, and an independent producer/voice talent.



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