New Gear Review: DM2 TNT by sE Electronics
“Whether you’re a podcaster, recording engineer, or running live sound, sE inline preamps are the perfect way to boost the signal from a passive mic.”
In recent years, the popularity of inline preamp “boosters” has exploded. A phenomenal number of users, from pros to hobbyists, have begun relying on these compact powerhouses to enhance their recorded audio. The proliferation of podcasts and video content creators has shown many people with small budgets still need to produce clear, quality sound. sE Electronics has a new contender to throw into the fray. Let’s see how their latest offering stacks up.
Features
The DM2 is an inline, phantom-powered FET preamp. The distinction between a preamplifier and an amplifier is relatively simple for those newer to these terms. An amplifier (such as a guitar amp) is designed to increase the amplitude of a signal. The term preamp indicates that it’s designed to increase the signal by a specified amount or to a specific level. A standard microphone preamp is a perfect example. They take tiny mic-level signals up to a line level, Where all other pro audio gear operates. Speaking of mic preamps…the DM2 does not replace your mic preamp but aims to enhance and augment what your mic preamp can do. The DM2 follows on the heels of the DM1 inline preamp released several years ago but differs in a few key ways. The DM1 offers a fixed gain of +28 dB; the DM2 provides a choice of either +15 dB or +30 dB of gain. Additionally, the DM1 has a fixed input impedance. The DM2 offers eight selectable input impedances. This option is where things get interesting (more on that later).
The DM2 features two small indented controls that allow for changes to the settings. A small slider switches between the gain settings, and a rotary control selects the various impedance settings. Both are small and recessed and tough to change without the included tool (or any other small, flathead screwdriver). One side of the device features a plug XLR, while the other features a socket XLR. It’s pretty easy to use. Just insert it between the mic and preamp, and engage phantom power.
We like to think of a mic as having a “sound.” The same thing holds true for a preamp. But the reality is that we don’t live in a vacuum. Any interconnected audio devices each affect the signal. A microphone and a preamp are not separate devices but rather an electrical system designed to convert sound pressure into a tiny electromagnetic signal and then raise it up enough to go off and play with all of your other pro audio friends. Thinking of it this way, it makes sense then that some mic/preamp partnerships work well while others fall flat. Some preamp manufacturers may use a design with a lower impedance as it allows them to publish lower self-noise numbers. You can see this frequently on budget preamps, mixers, and interfaces. Changes to the preamp and its impedance can affect the mic’s response in more ways than one. Condenser mics react less to these changes as they have an integrated impedance converter. However, dynamic microphones (both ribbon and moving coil) are sensitive to changes in impedance.
In Use
As a user of the DM1, I was excited to try the DM2. To see how it would perform, I ran it through many tests. First up was on room mics for drums. I love the sound of old ribbons on rooms, but the signal was pretty weak with a large room and a very distant pair of Coles 4038s. The two gain settings on the DM2 offered beneficial, clean boost settings, which allowed me to rely less on the console gain. Instant drum size with less noise during mix-down.
The next test was for podcast/home VO recording. Many people have an excellent mic, such as the Shure SM7. It sounds great, but the output can be low, especially on low-level or distant sources. This use is one of the areas where I think this device shines. An entry-level interface/mic combo saw vast improvements by inserting the DM2 in the signal chain, even when off the mic a bit.
Test #3 was on the electric guitar. I placed a vintage Sennheiser BF509 in front of my amp and let it rip. By that, I mean that I carefully measured and reamped the signal to ensure consistent performance. Additionally, I used a test tone and the variable output level on the Universal Audio Neve 1084 emulation to ensure all recordings were at the same level while keeping the 1084 gain settings identical. The pseudo-scientific method here aimed to keep all variables uniform except the impedance of the DM2. I wanted to hear how these changes would affect the performance. A significant side-note here is that the impedance pot is detented, and offers 360 degrees of rotation, so you can ramp up from the lowest impedance to the highest and then quickly switch back to the lowest to hear the difference easily. I ran the clip through at all eight impedances of the DM2, once using the DM1, and once without either.
Some mics are more affected by this than others, but I noticed two main things: A decent array of tones are possible using the impedance potentiometer. Bi-directional microphones exhibited were more or less unchanged in the top end. Cardioid mics reacted as though passed through a Tilt EQ. Omni mics tended to show a rise in the upper end. Keen observers may notice a correlation between the proximity effect and how this device alters the response. I spoke with sE’s product development team and they verified this. Remember what we mentioned earlier about interconnected systems and not living in a vacuum? I love this gig because the longer I do it, the more I learn how many things are tied together.
I noticed a substantial difference in the transient response of the mic depending on the impedance selected on the DM2. Low values tended to feel much softer and squishier, whereas higher values exhibited a stronger, tighter transient. If you don’t have a vast collection of guitars/amps/mics, this device would be a great addition to your studio just for the tone-shaping capabilities alone. Another nice feature about the DM2 (and DM1) is the small size and barrel shape. They can be plugged directly into almost any mic. If that looks bad (and in some video situations, that does matter) or is obtrusive, it can be connected directly to your preamp or interface. No extra cable is required. Lastly, this thing feels incredibly solid. While we should always be careful with electronics, I would not worry about this failing.
Lastly, it occurred to me that a DI also puts out a mic-level signal. I have some passive DIs made by BAE that sound awesome and a Fender bass (also excellent). While I love them both, the low output level of the bass asks a lot of any mic preamp connected to the DI. I tried the DM2 on this chain and found it useful for boosting and tone-shaping. How hard the front end of a mic preamp is hit has a lot to do with the sound, and this gives loads of extra options.
To Be Critical
A critique of this device is how difficult it can be to change the settings. The upside here is that the settings will never change accidentally and will stay where you set them. However, you will have to keep the included tool handy at all times. A related issue is that the impedance setting is challenging to read. Trying to do this on-stage or in a dark studio is even harder. A small application of paint (maybe even glow in the dark!) to the potentiometer to highlight the selection would help immensely. Other devices on the market offer a larger, easier-to-adjust knob, but all of those are larger, require an extra cable, and cannot plug directly into the mic or interface.
Summing it Up
The DM2 is a clear winner for the price. Especially considering there is an even less expensive model for those with simpler needs. Anyone who works with low output dynamic mics or records low-level sources under less-than-ideal circumstances can improve their sound quality without rendering some of them obsolete. Those with excellent mics and preamps already may not need this, but the ability to change the tone and response of any dynamic microphone can always come in handy. These tiny tools are portable, durable, and excellent for many applications.
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