The Rocktron HUSH PRO is a rack-mount noise reduction unit, which the maker describes as a "Stereo Noise Exterminator for studio and stage applications"1. It carries Rocktron's patented HUSH circuitry, a single-ended system that combines dynamic filtering with low-level downward expansion, and Rocktron states that when it is set up correctly the unit is "completely transparent, not affecting the audio signal, only the noise"1. It belongs to a HUSH line the company says runs back over two decades of products used by professionals1.
How the HUSH circuit works
HUSH is not a gate in the simple sense. Rocktron describes it as a single-ended system that combines the principles of dynamic filtering and low-level downward expansion1. In practice that means the circuit works on the signal as it passes through the unit, filtering and expanding the low-level material where noise lives, rather than cutting the audio off entirely. Rocktron calls it "the very best, award-winning, noise reduction circuitry possible"1, and the company has built the HUSH name into a range of products over the years, from rack units to pedals such as the Rocktron HUSH The Pedal and the Rocktron MicroHUSH.
Controls
The front panel carries two controls, and each one acts on both channels of the stereo signal at the same time1.
| Control | What it does |
|---|---|
| HUSH Threshold | Sets the amount of noise reduction required for a given input signal, manipulating both channels simultaneously1 |
Because both controls manipulate both channels simultaneously1, a stereo setup is dialed in as one system. There is no per-channel adjustment, which keeps the panel simple but means the same threshold setting governs the left and right sides.
Inputs, outputs and signal specs
The HUSH PRO provides both 1/4-inch and XLR inputs and outputs1, so it can be wired into a balanced line-level rack rig or a standard instrument-level chain. The measured specifications Rocktron publishes are:
| Specification | Value |
|---|---|
| Maximum input level | +15dB (+4 Ref.) / +5dB (-10dB Ref.)1 |
| Input impedance (1/4-inch jacks) | 470K ohms1 |
| Output impedance (1/4-inch jacks) | 100 ohms1 |
| Frequency response | ±.5dB, 10Hz to 27kHz1 |
| THD + Noise | .041% @ 0dBu, 1kHz (typ)1 |
| Dynamic range | 105dB1 |
| Noise floor | -100dBu1 |
| Current consumption | 405mA1 |
| Dimensions | 19" x 4" x 1 3/4"1 |
The unit draws 405mA1, which is well beyond what a standard pedalboard power supply output provides. It is a rack unit intended for mains-powered rack setups, not for a daisy-chained pedal supply.
Where it sits among the alternatives
Players who want HUSH-style noise reduction in a pedal format have Rocktron's own smaller units, such as the Rocktron Reaction HUSH and the Rocktron HUSH Noise Reduction pedal. The wider rack and pedal field includes units such as the MXR Smart Gate Pro Rack Unit and pedal gates like the Boss NS-2 Noise Suppressor and the ISP Technologies ISP Decimator II. The HUSH PRO is a 19-inch rack unit, at 19″ x 4″ x 1¾”1, and its single HUSH Threshold control sets the amount of noise reduction required for a given input signal, manipulating both channels simultaneously1.
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Questions
Is the Rocktron HUSH PRO a rack unit?
Yes. The HUSH PRO is a rack-mount unit, with dimensions of 19 inches wide by 4 inches deep by 1 3/4 inches tall, the standard height for a single rack space. It is built for studio and stage applications rather than for a pedalboard, and it continues a line of HUSH noise reduction products that Rocktron says professionals have used for over two decades.
Does the HUSH PRO have XLR connections?
Yes. The HUSH PRO provides both 1/4-inch and XLR inputs and outputs, so it can sit in a line-level rack setup with balanced connections or in a guitar-level chain with standard jacks. The 1/4-inch inputs present an impedance of 470K ohms, and the 1/4-inch outputs have an impedance of 100 ohms.
How much noise reduction does the HUSH PRO give?
Rocktron specifies effective noise reduction of up to 72dB, alongside a dynamic range of 105dB and a noise floor of -100dBu. The HUSH Threshold control on the front panel sets the amount of noise reduction applied for a given input signal.
Does the HUSH PRO work in stereo?
Yes. Rocktron describes it as a stereo noise exterminator, with two channels that are manipulated simultaneously by the front panel controls. There are two controls, and each one affects both channels at once, so a stereo setup is adjusted as a single system rather than channel by channel.
Where can I find the HUSH PRO manual?
Rocktron provides a Download Manual link on the HUSH PRO product page at rocktron.com, so the manual can be downloaded directly from the maker's own listing for the unit.
Sources (1)
- HUSH Pro Guitar Noise Reduction, Rocktron, 2024-08-28
