Transparent dynamics processing with tube-saturation circuitry.
The MindPrint T-Comp stereo tube compressor is a hybrid design employing both solid-state and tube circuitry. Additionally, the unit provides a control for adjusting the amount of drive sent to the tube, letting you fine-tune the tube saturation and thus dial in a range of tones from clean to distorted.
The 1U rack-mountable T-Comp uses THAT VCAs to control gain levels. It is also strictly a soft-knee compressor. You can use the T-Comp as either a stereo or dual-mono processor, and it provides both manual and semiautomatic modes of operation.
CHANNEL CROSSINGThe T-Comp crams a host of useful controls and LEDs onto its nicely organized and attractive front panel. Each channel offers separate, continuously variable rotary knobs (without detents) for input and output levels, threshold, ratio, and attack- and release-time settings. The knob settings, though, are hard to discern in low light or at more than an arm's length away.
A Link button enables stereo operation, in which the left channel's threshold, ratio, attack, and release settings control the processing for both channels. This feature works well and keeps stereo imaging rock solid. An LED illuminates whenever you depress the Link button.
Each channel also sports its own bypass switch. When a channel is bypassed, the input control remains active; however, the output-level control is disabled, as it should be. When the unit is turned off, the inputs become hardwired directly to the outputs - a nice safety net for live and broadcast applications.
With processing switched in, the processed signal's output level can be increased to roughly equal that of the unprocessed signal. This operation, called makeup gain, allows critical A/B comparisons of your starting material with what you ended up with. (The input-level controls are active regardless of whether the unit is bypassed.)
Maximum input and output levels are 20 dB, which is a little on the wimpy side. However, input (and output) knobs attenuate to -??? in full counterclockwise position, allowing plenty of compensation for use with hotter equipment (although possibly at the expense of signal-to-noise ratio). I wish the level knobs were screened in decibels instead of in arbitrary numerals of 1 to 8, to assist in proper gain staging. There are no unity-gain hash marks on these knobs, either. My tests with an oscillator, though, indicated that unity was roughly at the noon position for both knobs.
COMPRESSING ONThe T-Comp's threshold range varies from +2 to -28 dB, slightly favoring semipro operating levels. You can turn down the input level if you can't get the threshold high enough, but then you risk decreasing the signal-to-noise ratio. For tracking purposes the input level and threshold ranges are usually quite adequate; using the T-Comp as a stereo bus or mastering compressor, however, could be a little dicier, depending on your gear's output level.
The T-Comp's wide-ranging attack, release, and ratio controls provide excellent flexibility. Most of the ratio knob's turn is devoted to lower ratios. (Once you're past 10:1, additional compression through higher ratios becomes increasingly less noticeable on all compressors.) The T-Comp provides high ratios for limiting, although there is understandably some overshoot (that is, the unit does not do brickwall-type limiting).
An adaptive circuit can also be switched in independently for each channel. This is similar to the auto-mode circuitry found in some compressors, except that the attack and release manual control settings still dramatically influence the compressor's response. Nevertheless, the adaptive mode smooths away any pumping that less-than-optimal manual settings might otherwise produce. Switching in the adaptive mode after setting ballpark manual settings yields the best results. The adaptive function lacks a status LED to indicate that it is switched in, but that's a minor gripe.
The T-Comp also features a filter switch (with LED) for each channel. This inserts a highpass filter, set at 300 Hz, into the compressor's sidechain. The idea is to roll off the bass frequencies in the sidechain so that the T-Comp responds primarily to mids and highs - a technique that is especially useful for putting a lid on soaring vocals. However, a preset filter band cannot provide nearly as much flexibility and power as do sidechain inserts, which the T-Comp regrettably does not offer. The lack of sidechain inserts prevents the unit from performing more exacting "frequency-conscious" tasks such as de-essing and debooming.
TUBE JOBPerhaps the T-Comp's most intriguing feature is its tube-saturation circuit, which employs two 12AX7A tubes, each positioned after the VCA (that is, postcompression) on both channels. Independent Tube Sat controls - one for each channel - allow you to adjust how hard each tube is driven into saturation. (Note that the threshold knob's setting also contributes to the amount of tube saturation produced.) As the tube is driven harder, distortion increases from 0.1 to 10 percent, and an increasing treble boost (maxing out at 2 dB) is applied from 4 to 22 kHz. A multicolored LED also transitions from green to yellow to red as saturation increases. (This same LED shines green when a compressor channel is switched in.)
METERS AND MODSThe T-Comp's metering is exceptional. Separate 6-segment, multicolored LED meters for each channel can be switched globally to display either input or output levels. In addition, separate high-resolution, 12-segment LED meters show gain reduction for each compressor channel.
A power switch (with associated LED) and an analog/digital input switch complete the unit's front panel. Lest there be any confusion, the T-Comp is an all-analog device: the digital input setting lets you send digital signals through the optional DI-MOD converter ($249), which installs on the T-Comp's rear panel.
My review unit wasn't outfitted with the DI-MOD, but here's the skinny just the same. The DI-MOD provides 24-bit Crystal A/Ds and D/As for bringing digital signals into the T-Comp's analog world through stereo S/PDIF inputs on RCA connectors. This same option is found on MindPrint's EnVoice processor, so you can freely swap it between units. The converters sport a 104 dB dynamic range - not bad for such a low price. However, dither and word-clock I/O are not provided. The DI-MOD can operate at 44.1 or 48 kHz, and an LED illuminates to show digital sync lock.
IT'S OFF TO WORK I/OFrom its rear panel the T-Comp accepts either balanced or unbalanced signals straight out of the box. Combo jack inputs accept XLR and TRS/ mono 11/44-inch plugs for L/R inputs. Separate XLR and TRS jacks provide outputs for each channel.
Note that pin 2 of the XLR and the phone jack's tip are hot. If you insist on taking an unbalanced signal into or out of the T-Comp through an XLR connector, you must shunt pins 1 and 3 together. Thankfully, there's no need for that hassle - inserting a mono phone plug into an input or output automatically switches the unit to unbalanced operation. You can even use the XLR and TRS outputs simultaneously, so as to split the signals to two destinations (that is, as long as both outputs are balanced). This operation could prove useful in situations where, for example, you want to route the same signal to two separate mixer channels for different EQ treatments.
The T-Comp also provides 11/44-inch TRS insert points on its rear panel, allowing you to insert an equalizer or other processor directly into the audio path before the VCAs. (Remember that this operation is different from inserting a processor into the sidechain.) With the DI-MOD installed, the inserts also let you patch additional analog gear between the converted S/PDIF signal and the T-Comp's compressor section. (Of course, even without the DI-MOD installed, you can daisy-chain other gear ahead of the T-Comp to achieve essentially the same results.) A detachable 3-prong AC cord and ground lift switch complete the T-Comp's rear-panel assets.
IN SESSIONI first tested the T-Comp with a strummed acoustic guitar. I dialed in a 2.5:1 ratio and was pleased with how transparently the unit achieved 4 to 6 dB of gain reduction. There was neither dulling of the guitar's timbre nor any audible pumping or breathing. The only downside was that the unit is quite noisy, adding roughly 12 dB of noise at unity gain - and that was with the tube-saturation function turned all the way down.
Except for the noise problem, the T-Comp was great on vocals. I easily attained 8 dB of gain reduction on a vocal track without introducing any audible amplitude-modulation artifacts (pumping, for example).
The T-Comp was equally transparent on a snare-drum track during a rock mixdown session. Set to a 3.5:1 ratio, 10 ms attack time, and 100 ms release, the unit delivered a fantastic "power pop" snare, bringing up the attack of the stick hit and tightening up the shell resonance for a crisp and punchy sound. By varying the ratio between 3.5:1 and ???:1 (hard limiting), I controlled how much shell resonance contributed to the overall sound.
The T-Comp also did a very good - although not superb - job as a stereo-program bus compressor. But although there was no obvious pumping when the unit was set properly, the sound was a tad choked or flattened. I don't want to overemphasize this, however, because the T-Comp did a better job in this application than most compressors I've heard.
The unit also delivered the goods on an overenthusiastic electric bass guitar track. I was able to lower the T-Comp's attack time to 0.2 ms to soften the track's attack without introducing any pumping.
Cranking the unit's tube-saturation (Tube Sat) knob on the bass track gave mixed results. On the one hand, it fattened the track, making it sound as if the amp had been turned up loud and the speaker was just beginning to break up (in a flattering way). Yet the increase in high overtones made minor fret-slap sounds obnoxiously present. Make sure to use the T-Comp's tube saturation only on cleanly played tracks, and listen closely for emphasized artifacts.
SATURATED MARKETDespite our industry's mad love affair with tubes, glowing glass alone does not guarantee the perfect tone for every application. Overall, the T-Comp's tube-saturation function was unimpressive, being more akin to a distortion pedal than to a high-quality tube preamp. Rather than making tracks sound lusher, Tube Sat mostly made them sound dirtier. It could be cool for adding grunge to a track, but if you want to fatten up tracks while preserving pristine signal quality, the T-Comp's tube-saturation feature is not the way to go.
On a related but less important note, the unit's tube-saturation LED is not very responsive. I drove the tube hard enough to clearly hear distortion, yet the LED remained green (its resting-state status).
RANGE OF MOTIONMindPrint's T-Comp is a well-featured stereo compressor that delivers the goods where it matters most - transparent dynamics processing. Unlike many competing models, the T-Comp did not fall down when pressed into processing broadband percussive material (stereo mixes, for example). However, the unit is quite noisy and it lacks the headroom needed for audiophile recording applications. Moreover, the absence of sidechain inserts precludes the use of advanced frequency-dependent processing techniques.
Unfortunately, the T-Comp's tube-saturation circuit has only limited usefulness - despite being a featured function. The distortion it adds sounds fairly dirty, so it's better as an effect rather than for fattening up tracks. Just the same, the T-Comp is priced attractively enough to warrant serious consideration by budget-conscious studio owners looking for good dynamics control.