A noise gate, though not the most glamorous of components, is an essential part of any well-equipped multitrack studio. By reducing noise, including leakage from headphones and neighboring instruments, the gate plays an important behind-the-scenes role, helping maintain the spaciousness and background clarity of a mix. In particular, live ensemble recordings, amplified instrument tracks, and drum tracks can benefit greatly from careful gating.
If you've had your fill of bare-bones noise gates that cause as many audio problems as they solve, check out the DS501 Power Gate from Drawmer, the company that has pioneered gating technology since the early 1980s.
A sophisticated dual-channel noise gate, the DS501 is sized to fit into a single-rackspace box (see Fig. 1). Its two channels can be linked in stereo or used on two separate mono sources. Left and right channel controls are completely independent and are laid out side by side on their respective halves of the front panel. The Stereo Link switch is located in the middle of the unit, and the Power switch is on the far right.
Drawmer incorporated several features not commonly found on noise gates into the DS501, but I'll discuss the unit's more conventional parameters first. The DS501's five continuously adjustable rotary knobs provide control over all aspects of a gated signal's envelope and dynamics. Those are, from left to right: Thresh (threshold), Attack (attack time), Hold (the length of time the gate is held open after the signal drops below threshold), Decay (the rate at which the gate closes after the signal drops below threshold), and Range (the amount of attenuation applied to the signal once the gate closes). The Range control remains active on each channel when the noise gate unit is in Stereo-Link mode.
Those parameters should be familiar to anyone who has used noise gates before; however, finding all of them on one unit is rare. A vertical four-LED ladder meter next to the Threshold control indicates signal strength relative to the selected threshold; a red light at the top of the display corresponds to above-threshold or gate-open status. Three LEDs across the top of the Gate section indicate gate status: red shows when the gate is closed, yellow indicates hold status, and green confirms that the gate is open.
A two-position Function switch selects Gate or Duck mode. Ducking is a common voice-over and broadcast procedure whereby a key source (a narrator's voice, for example) is used to automatically attenuate a music bed or other track. For that function, the Range knob governs the ducked audio's gain reduction when the vocal or other key input is present. Rounding out the Power Gate's feature set is an Output switch with three positions: bypass, gate, and key listen.
Typically, a noise gate opens and closes in response to the voltage of the audio signal that it's gating, but an external signal connected to a key-input jack can also trigger the gate's detection circuitry. The key input is usually the same audio track but processed through outboard EQ to boost or eliminate certain frequencies. When gating a kick drum or floor tom, for example, it may be advantageous to remove some high frequencies so snare and cymbal sounds are less likely to trigger the opening of the noise gate. Likewise, boosting those drums' resonant low frequencies will tend to hold a noise gate open longer, producing a more natural decay characteristic.
The DS501 is unique in that it allows onboard equalization of internal or external key signals. That function, one of the unit's extra features, is handled in the Key Source section, which is located to the left of the conventional gate controls for each channel. The Key Source section provides a two-position switch labeled Ext/Int and two continuously variable knobs for setting low-frequency and high-frequency filters. The two shelving-type filters sharply reduce frequencies below the selected low corner frequency and above the selected high corner frequency.
Setting the Ext/Int switch to Int (internal) allows the type of key filtering described previously, but without the need for an outboard equalizer; switching it to Ext (external input) permits ducking and other specialized applications. A kick drum, for example, can be used as an external key input to trigger and tighten up a bass guitar's attack in the mix. You can also construct wild effects by keying from metronomes, CDs, vocals, or other sources to gate or duck selected tracks. In addition, you can route the key source and any associated EQ processing to the DS501's outputs simply by switching the Output switch to the key-listen position — a handy feature that lets you hear exactly what you're keying with.
Another Power Gate innovation called Peak Punch allows for tunable transient boosting. Located to the right of the gating controls, the Peak Punch section provides a three-position switch and two continuously variable knobs marked Tune and Level (see Fig. 2).
The three modes accessed by the switch are Bypass (marked “Out” on the front panel), Full-Band (marked simply “Full”), and Frequency-Tunable (marked with an EQ-boost graphic). In Full-Band mode, you can boost the signal as much as 12 dB using the Level knob (arbitrarily labeled 1 through 10). In Frequency-Tunable mode, you can apply as much as 12 dB of gain to a specific frequency range, which is determined by the Tune control. In both active modes, the Peak Punch circuit provides a 10 ms gain boost every time the gate opens, reinforcing the initial transient of the gated audio.
ON THE FLIP SIDE
The DS501's rear panel provides +4 dBu balanced XLR connectors for input and output (see Fig. 3). There is no provision for -10 dBV signals, and unbalanced operation requires custom cable soldering. A 2-conductor ¼-inch jack on each channel accepts key-input signals. The unit has a standard IEC power-cord jack. Voltage selection and fusing are located inside the sturdy all-steel chassis and thus are not accessible without opening the unit.
Drawmer prepared a clearly written and comprehensive manual with helpful diagrams; five minutes with that exemplary manual were all I needed to decode the DS501's more esoteric features.
Drums are typically the most difficult instruments to gate properly. While testing the Power Gate, I focused on a variety of challenging sources from a standard rock drum kit. Starting with kick drum, I was immediately impressed by the sensitivity and forgiving nature of the DS501's attack control. With proper adjustment, that feature allows a musical softening of the kick drum's attack without the audible clicking that severely lessens the usefulness of some gates. I also appreciated the continuously variable Range control. Typically, 20 to 30 dB of gain reduction is all I require for most gating applications, and having control over that parameter certainly contributed to a more natural sound.
The Power Gate's key filter is another powerful feature. It proved especially useful for tuning out snare sound on the kick track. But the key filter must be used in moderation in that application because the high frequencies of the beater attack are crucial for opening the gate and the lows keep it open. When set higher than 3 in full-band position, the Peak Punch elicited an unpleasant pock from the kick track. In Frequency-Tunable mode, low-end boosting added an undesirable boxiness to the sound and was not effective for adding any real punch. Set above 1 kHz, however, the Peak Punch was handy for boosting the click of the beater and helping the attack to cut through. Precise boosting in that fashion should work well to enhance kick-drum sounds in a range of musical styles.
It took me two passes through a standard three-minute song to dial in a tight, perfectly controlled kick-drum sound. The Bypass switch allowed a quick A/B comparison of the gate's comprehensive and precise control. Once adjusted properly, the bypass contributed no significant coloration; all that was missing from the kick track was snare-drum, cymbal, and bass-amp leakage. Switching between Bypass and Gate modes produced no clicks or muting of the audio, a point that further underscores the DS501's professional quality.
Another test track presented a challenge: a rack tom had been hit very lightly, which typically makes for difficulty in setting a reliable gate without getting a lot of snare bleed. The Power Gate's key filtering took charge of the situation by letting me lower the high-frequency shelving EQ and tune out a lot of the snare sound. In addition, a low-frequency cut seemed to tighten up the rack-tom triggering, as did a slight lengthening in attack time from 10 µs to 0.1 ms. Finally, a light Peak Punch boost at 500 Hz gave the tom track more tone — a save that left me with the impression that this innovative module could help a dead-sounding drum have more life in a mix. You can also use Peak Punch to add a bit of gain and aggressive attack to a drum track, which is especially helpful for rock mixes because the toms always seem to need an extra boost.
I got similarly positive results with the Power Gate on floor tom, although a longer decay time (about 1.5 seconds) was necessary. Thanks to the Peak Punch's Frequency-Tunable mode, I was able to enhance punch at 200 Hz or sharpen the high-end attack around 3 to 4 kHz. The short (10 ms) duration of the Peak Punch circuitry let the drum cut through a dense mix without unwanted coloration or the type of onboard EQ boosts that make a dull floor tom sound papery or thin. Nice trick, Drawmer!
SNARE THE PRIZE
Snare-drum gating is something I rarely do; typically, I reserve it for situations in which tight gating is required to keep an extreme effect confined to only the snare. To test the Power Gate's mettle in that application, I chose a track titled “Dance Craze Time” that I recorded for the Casino Royale CD Where's the Tiger? (Double Play, 2001). On the song, drummer Wes Anderson's snare work includes a variety of hits, from subtle rim shots to full-on power backbeats. Gating the track was a challenge, and initially I had a lot of trouble with a dull, “boinky” tonality from the snare. In addition, certain kick-drum hits kept triggering the gate. Then I realized the Peak Punch circuit was engaged and the Level control was set at 7.
Switching Peak Punch out made the track significantly more manageable. I employed some key filtering below 250 Hz, and careful adjustment made every rim shot audible, with bass-drum attacks sneaking through only occasionally. Using the high-frequency shelving, I also filtered out the hi-hat somewhat. Again, slightly reducing the attack (to a setting just under 0.1 ms) minimized false triggering and gave the snare a more natural sound. Finally, I reengaged the Peak Punch function and set the Tune control to 4 kHz and the Level control to 4, which gave the drum a bit more edge in the mix. Thanks to the DS501, gating was no longer a dreary chore; it was actually creative and fun.
While testing for coloration added by the DS501 (with Peak Punch out), I detected a slight increase in highs and definition on the snare track when I switched in the gate. Technically, any kind of coloration in a device such as the DS501 should be considered a flaw; in this case, however, the subtle change was beneficial. Is it possible, after all, to have too much definition on a drum track?
In its Stereo-Link mode on drum-overhead tracks, the Power Gate also performed impressively on a light, skittery jazz-drum performance. Indeed, the unit seemed to anticipate every nuance. A longer decay time (one second or more) made the gate's processing practically undetectable.
Using the Power Gate's key filter, I achieved interesting gated-reverb effects by tuning the gate to open for kick drum or snare hits on ambient room mics. I've also been known to gate an entire drum set as an effect, and when stereo-linked for that application, the DS501's ample controls did not disappoint me.
I had fun using the Duck control to attenuate rather than pass audio whenever a drum was hit. By suppressing all rhythmic accents, I created an “antidrum” track that let only cymbal decays and rests come through. Although it's not an effect I use often on drums, ducking is a powerful option in the Power Gate's toolbox. A more common musical use would be to automatically reduce the level of loud guitars under a lead vocal.
RUNNING THE GAMUT
I was not expecting gating miracles when I tested the Power Gate on a quiet, avant-garde vocalist in a live-ensemble setting. Key filtering, however, proved invaluable for homing in on the singer's range and tuning out other instruments in the room. When whispery passages dropped below threshold, setting the Range control to a gentle -10 dB made it possible to achieve some gating control without completely losing the source.
On saxophone and oboe, giving a little extra attention to the DS501's Attack, Hold, and Key Filter settings paid off quickly, allowing soft, airy notes through without clipping off too much of the initial breath sounds. An atmospheric guitar track, produced by stroking the instrument with a rubber mallet, also proved surprisingly “gateable.”
On nonpercussive sources such as synthesizer washes and volume-pedal guitar swells, gating is often more trouble than it's worth. But once again, the Power Gate's smooth attack characteristics proved a joy to use. In fact, during all of my testing, the only instrument that didn't really benefit from a detour through the Power Gate was a softly bowed cello.
While using the DS501 daily on several sessions, I encountered no problems with headroom, distortion, or noise. Indeed, I ended up with only one minor complaint: when adjustments of a few milliseconds are crucial, the Power Gate's small knobs and tight, tiny legends are less than accommodating to the fingers and eyes. Every one of the Power Gate's 18 rotary controls and 10 switches is essential, however, and getting them all on the face of a 1U box amounts to a minor miracle. Considering the versatility and depth of control options, it is a small inconvenience to adjust to the DS501's somewhat cramped faceplate.
Before using the Drawmer DS501 Power Gate, I had regarded gates as a necessary evil. I never relished using them, largely because of their lack of parameter controls, but the Power Gate has changed that perception for good.
Aside from the unit's small knobs, the only problem I had was figuring out how to afford eight Power Gates for my 16-track analog studio! The key-filtering feature makes so much sense that I can't imagine ever trying to gate a track without it. Although they are specialized functions, Duck and key listen expand the unit's appeal to include post-production and broadcast applications. The Peak Punch circuit, though best used in moderation, is a powerful problem solver for drums and other sources. The Power Gate is a well-built, professional tool that not only gets the job done right but also opens up a world of creative possibilities beyond the drab, utilitarian role usually assigned to noise gates.
Myles Boisenis a guitarist, producer, composer, and head engineer and instructor at Guerrilla Recording and the Headless Buddha Mastering Lab in Oakland, California. His e-mail firstname.lastname@example.org.
DS501 Power Gate dual-channel noise gate $550
FEATURES5.0EASE OF USE5.0AUDIO QUALITY4.5VALUE5.0
RATING PRODUCTS FROM 1 TO 5
PROS: Full-featured. Minimal coloration. Innovative key-filtering and Peak Punch features. Dual-mono or stereo-linkable operation. Easy to use on problem sources. Noiseless bypass switching.
CONS: Small knobs and legends.
DS501 Power Gate Specifications Inputs(2) +4 dBu balanced XLR; (2) ¼" keyOutputs(2) +4 dBu balanced XLRMaximum Input Level+17 dBuMaximum Output Level+17 dBuFrequency Response23 Hz-31 kHzDistortion (@ 0 dB input)<0.025% (100 Hz, 1 kHz, 10 kHz)Noise (RMS)-93 dB (22 Hz-22 kHz, unity gain, gate open)Threshold Range• to -72 dBFSAttack Time Range10 µs-1 sec.Hold Time10 ms-2.5 sec.Decay Rate5 ms-4 sec.Range of Attenuation-80 dB-0 dBLow-Frequency Filter25 Hz-3 kHzHigh-Frequency Filter250 Hz-30 kHzTunable Transient-Boost Circuit10 ms boost; 0-12 dB gain (variable);(Peak Punch)75 Hz-16 kHz (variable peak filter)Dimensions1U × 7.9" (D)Weight6 lb.