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Kush Audio Gain Train

A good monitor controller is invaluable — but 'good' doesn't have to mean complicated...

Kush Audio Gain Train

Kush Audio are a company that I know from some fantastic-sounding outboard (including the Clariphonic EQ), and one of the nicest software dynamics processors I know of, the UBK1. When I was testing the UBK1, it was suggested that I also take a look at Kush's Gain Train, which is a modular monitor-control system comprising two different elements: the Main Gain and the Function Junction. Being a fan of rhyming epithets, I could hardly refuse...

Both devices are designed for desktop use, and there's a neat system for joining the two units together to make one: a multi-channel port on the side connects the two, and a plate swings round on the base to make the connection secure. Very neat. The Main Gain can, as the name implies, be used as a stand-alone monitor controller, and the Function Junction is an extension unit which adds to the, um... functionality.

Main Gain

The Main Gain offers only one stereo input and one stereo output, so there's no switching between different sources and destinations if this device is used on its own. What it does offer is a chunky volume-control knob, which affords you fine control over the output level, and a variety of monitoring facilities. There's a switch to sum the signal to mono, so you can check for phase problems in your stereo source quickly and easily. You're also presented with independent muting of the Left and Right channels, as well as a neat, dual-channel, tri-colour LED level-meter. What you don't get is any noticeable coloration of the sound: what goes in is what comes out — it compared well in this respect with my Dangerous D-box, which is no slouch. In more technical terms, the frequency response is within ±0.1dB from 2Hz to 20kHz, and only 3dB down at 200kHz. Impressive.

Function Junction

Kush Audio Gain Train

Kush evidently wanted to keep the Main Gain simple, because if they'd loaded it with functionality it would have pushed the price beyond the reach of some potential purchasers who only need a simple stereo device. For those who want more, they produced the Function Junction. This couples with the Main Gain to add a further two stereo sources and destinations to the system, as well as a talkback facility and a pair of high-quality headphone amps. The talkback facility mutes the program material automatically, and while I'd prefer it if there were the option to set the degree of attenuation, it's a helpful facility.

The I/O is presented via a 25-pin D-sub connector, which makes the cabling as neat as is possible when all the electronics are housed in a desktop unit. That brings me on to my only significant criticism: the desktop design requires you to have cables dangling off the back, so you'll either need to leave these on display, or have a strategically positioned hole on your desk through which the cables can disappear. A rackmount device doesn't suffer from the same problem. The counter argument is a strong one, though: by having the controls directly in front of you at the listening position, you're able to make judgments about the sound without having to stretch over to a rack (moving your ears out of the sweet spot in the process). It's something you'll need to make your own mind up about.

The review units seemed well built, and the tall, tapered shape of the volume knob makes it easy to use. I should note that there was a sticking button on one of the units. This didn't affect operation a great deal, and didn't colour the sound at all. Having checked this out with Greg Scott at Kush Audio, it appears that it was due to an issue with the metalworking on the first few units, causing the physical button to catch, and this has now been corrected.


In summary, this is a very transparent-sounding, active, modular monitor-control system — and a bloody good one at that! It provides a simple interface for a simple but important job, and does so without messing with the sound. It may not be the cheapest monitor controller system in the world, but it's still keenly priced in relation to many units of comparable quality.  


There's plenty of choice when it comes to active monitor controllers at very different prices and offering vastly different functionality. At the lower end of the price scale are units by Samson and Behringer. Upping the budget takes you to Mackie's Big Knob and a couple of Presonus products. TC Electronic offer some very good monitor controllers for the price. Given the choice, though — assuming they meet your functional requirements — I'd be sorely tempted to consider the Main Gain or full Gain Train, which offer performance (if not the degree of functionality) to rival pricer devices from the likes of Crookwood and Dangerous Music.


  • Very clean-sounding, with a ruler-flat frequency response.
  • Intuitive interface.
  • Modular: you're not paying for bells and whistles you don't need.
  • Good headphone amps on the Function Junction.
  • Desktop design means that controls are within easy reach of the mix position.


  • Desktop design: cables trail from the back.


If you need a simple monitor controller, the Main Gain is well worth checking out: it provides exactly what you need to a decent quality. If you work with multiple sources and artist monitor mixes, the Function Junction turns this into a comprehensive system.


Gain Train £834; Main Gain/Function Junction £466.80 each. Prices include VAT.

Unity Audio +44 (0)1440 785843.

Gain Train $998; Main Gain/Function Junction $499 each.