sE Electronics DM3 is a DI Box that’s actually cylindrical and performs brilliantly

The sE Electronics DM3 is a phantom powered DI box with features that put it in the expensive range, but costs only €119 EUR.

A “direct box” is a small connection box for instruments and line signal equipment. Cheap DI boxes have a 1/4in input to connect an instrument such as a guitar and an XLR output that send the signal to the mixer, console or audio input. Somewhat more expensive models have a ground lift switch to correct ground loop noise and/or a pad switch to accommodate different signal source levels. Expensive DI boxes have more features, such as a preamp and they’re powered.

The DM3 active inline DI box is intended for use with any 1/4in instrument cable. You can hook up instruments, but also playback devices that you can hook up with a 1/4in unbalanced cable for the audio output, like a keyboard, drum machine, synthesiser and even an iPad or FM/MW/LW radio as I found out.

The DM3 has the typical cylinder shape of the DM product range that includes the DM1 and DM2 microphone inline preamps. In contrast to its predecessors, it has an Ultra-HiZ input that allows for generous headroom for even the hottest devices. It has a ground lift switch with a mysterious ON setting. The ON setting contains new circuitry that helps reduce unwanted noise in both the low- and high-frequency range. That’s a boon for hum that gets generated by, for example, mobile phones.

Another switch allows you to attenuate the signal by 15dB or 30dB. The switches, as with the DM2, are recessed and require a small screwdriver to change them. A tiny one comes in the box, just as with the DM2.

Another great feature is the 1/4in input jack lock to prevent accidental disconnects. Some competing products have that on a combination XLR/jack port, but those locks only protect the XLR plug, not a jack plug.

sE Electronics has fitted out the DM3 with a dedicated Class-A output buffer amplifier and the whole device is encased in a slim, all-metal discrete housing that never gets in your way because of its cylindrical form factor.

I tested the DM3 with a variation of equipment, including an old B&O radio, a UNO Synth Pro, and the iPad. For each of these, I plugged the device in my Apogee Element 24’s Neutrik combo port set to Instrument and then, with exactly the same output from the device, through the DM3.

I couldn’t notice any changes in sound characteristics. The lows were the same as were the highs. That is surprising because the preamps on the Apogee are world-class and one would expect even a small noticeable difference in favour of the Element 24. In RX 10 Advanced’s spectrogram, however, I saw a quite dramatic difference when recording a silent device — in this case, an iPad. The Apogee set at a level of 45dB recorded quite some low-frequency noise coming from the iPad at a level of -70dB.

The DM3 set at no attenuation and the Element 24 consequently set at 34dB of gain, resulted in noise in the same range at -84dB. It means that sE Electronics aren’t lying when they tout the DM3 as giving much headroom as the noise levels with a DM3 are actually lower than with only an Element 24.

That is, in my opinion, a firm recommendation to use a DM3, even if you have a high-quality audio interface like my Apogee Element 24.

In short, when you need to plug a passive instrument like a guitar, or a device like a synth or a computer output into a mixer or audio interface, the DM3 will transport your signal without noise but with all the detail the original is capable of generating.

The DM3 retails at
119 EUR and is available now.

Technical specs

Electrical Impedance: 86 Ohms
Recommended Load Impedance: >1K Ohms
Input: 6.3 mm (1/4 in.) TRS jack
Output: 3-pin male XLR connector
48V Phantom Power required (P48 according to IEC 61938)

Frequency range: 10 Hz – 120 kHz (-0.3 dB)
Current consumption: 3.8 mA
Max input level (0.5% THD): 19 / 34 / 49 dBV (9.0 / 51 / 285 V)
Output noise level: 1 μV


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