TC Electronic C400XL

I bet you’re expecting what I was expecting when I first heard about this product —  another two channel box with the standard ratio, threshold, attack, and release controls, and maybe a stereo link. But there’s a lot more going on in this unit than you might think: tons of presets, multi-band dynamic compression, and parallel processing . . . let’s check it out.
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You can configure the two channels as two independent mono engines (which can be effective as two inserts on two separate tracks), as a stereo unit, or run them in “serial” mode, where the signal passes internally from the output of channel one into the input of channel two. This is perfect for when you want to use both a gate and a compressor on one track. Very cool.

Eighteen presets cover most instruments, like kick drum and bass guitar, as well as de-essing and de-hissing applications. These presets set the multiband compression, limiting, expansion, and gating parameters, and are especially helpful in “on-the-fly” live scenarios (for which the C400XL is ideal, in addition to its studio capabilities).

Each compressor has controls for threshold, ratio, makeup gain, and mix of the processed and straight levels. The gates offer control over threshold, ratio, release time, and processed amount. There are also input meters, as well as a “damp” meter that indicates the amount of attenuation from –1dB to –24dB. In addition, a threshold LED can notify you either of levels exceeding the preset threshold in the multiband compressor, or the input signal triggering the peak limiter. Around the back, you’ll find XLR stereo connections, AES digital in and out jacks (also XLR), and MIDI ports for uploading software.


I’ve been finishing up a four-song EP, so I decided to put the C400XL to test on the mix, working from the kick drum up. Putting the unit in dual mono mode, I inserted the C400XL into my console, setting the preset to Bass Dm. After a few tweaks (setting the threshold at –40 and the ratio at 3), and applying a total of about –6dB of compression, I had a pretty good sound.

I then tried out the gate. For those not familiar with gates, they’re designed for reducing noise and act like an audio “door” that opens and closes, letting the signal through or blocking it. The threshold control determines when the door will open based on the input signal level (i.e., low-level signals like hiss aren’t sufficient to open the gate, but higher-level signals are), ratio sets how long the gate stays open, and release determines how fast the gate closes.

The gate worked wonderfully, but I noticed that I couldn’t retain the “click” of the kick drum with the gate engaged. Usually I’ll set the threshold very high to get a click from the gate opening really quickly, but presumably there’s a very short attack time because I couldn’t achieve this effect with the C400XL.

Still, the kick sounded good, so I moved to the snare. As I wanted to use both the gate and the compressor, I set the unit into dual mono mode. The drummer was playing his hats louder than his snare, so I wanted to use engine one as the gate to help get all that hi-hat out of the snare track. Hitting the gate hard (with a high threshold setting) solved this problem nicely, perhaps better than some of my other gates would have.

Engine two was the compressor, so I set the preset to Snare Dm and started tweaking the threshold. I understand now why this unit is so good for live apps: The threshold knob has a ton of play, and you can affect the level of compression greatly by slight knob adjustments. But this brings me to my main gripe with the C400XL. Typically when adjusting compression levels, I’ll watch the meters as I get the desired amount of gain reduction, then do a “reality check” by hitting a bypass button to compare the processed and dry sounds. But on the C400XL there is no bypass button — the compressor is bypassed only when the mix knob is turned all the way to the left while, generally, I will have the knob turned all the way to the right. This is annoying, and I hope TC adds a bypass button on their next generation of this box.

But it sounds good, so I can’t complain much. Adjusting the makeup knob to set my levels, I recorded the C400XL’s output into Pro Tools so I could use the processed snare track in my mix, and free up the unit for the bass track.

Or should I say, “bass tracks.” I had three: a DI track, a signal from a sweet Ampeg SVT 3 Pro, and a SansAmp track. Usually, I just run to my Universal Audio 1176 to compress bass. Old habits die hard, but it was fun to work with something else for a change. Inserting the C400XL into the DI channel of my console, I turned the preset to Bass Guitar, set the ratio to 4, and cranked the threshold until I got about –12dB of compression. I was beating the hell out of the track, and I noticed that the C400XL performed similarly to the old dbx 160X, as it added a good amount of “gloss” and “polish” to the DI track. After mixing in a bit of the amp and the SansAmp signals, we were good to go.

The vocalist I was working with, Malachi Jagger, has an extremely smooth and well-controlled voice, so I wasn’t looking for a compressor to keep his volume under control; I needed something to help his voice stand out in front, and cut through the mix. So I inserted the C400XL, set the preset to Male Vocals, used a ratio of 5, and achieved a good sound that was fairly transparent. Still, there was a bit of sibilance to his track, so I used the De-esser preset at about 6kHz, and really cranked it up. Perfect — just what I wanted.


This is not at all your typical two-channel gate/compressor combo; it has some unique features that are usually found only in much more expensive units. The presets are incredibly helpful, and they make this box useful in both live sound and studio recording environments. So if you’re looking for something that can pull double-duty, want multiband compression with parallel processing capabilities, and excellent sound quality, for the price the C400XL really can’t be beat. Now if they would just add a bypass button!

Product type: Stereo/dual mono/serial compressor with gate.

Strengths: Sounds great. Short learning curve. Useful choice of presets. Good metering capabilities. High bang-for-the-buck ratio.

Limitations: Needs a bypass button, not just a mix knob. Weird jacking system around back (all are upside down). Tough to get a “click” out of the gate if you want it.

List price: $349