LA Audio Can-D

Photo: Mike Cameron

A dedicated headphone delay might seem like a bit of a luxury, but it could make life a lot more pleasant for the working engineer.

There's something quite irritating about wearing headphones when mixing front-of-house. Engineers spend substantial amounts of money on high-quality headphones offering good isolation and a decent frequency response, yet can still end up hearing a confusing mess of delayed and direct sound if the concert is loud enough and the venue big enough, because the sound arriving at the headphones is out of time with that coming from the speakers and stage. LA Audio have come up with a simple solution to rid engineers of this problem: the Can-D, a dedicated headphone delay unit.

The Can-D allows the engineer to delay their headphones to be in time with the speakers and stage, providing coherency between the PA and headphone sound. As the device allows delay times of up to 678ms, you could happily be 226 metres away from the stage and still listen to headphones in time with the FOH system (if you're engineering a concert twice the size of Glastonbury, I assume!). Simply plug the headphone output of the desk into the rear of the Can-D, and your headphones into the front, and you're off.

The Package

My first observation about the Can-D is how solidly made it is. This box is designed to be tour-worthy, and I was pleased to see it incorporating an internal power supply on an IEC mains connector. It's very sturdy and I feel sure the solid metal shell could withstand some punishment. The Can-D is small, at 105mm x 185 x 43mm, and only weighs in at 580g, so it's very portable. It's designed to sit on top of a desk within easy reach of an engineer mixing, and it works very well like that, but for touring purposes it might have made a bit more sense if it had been a 1U rackmountable unit that could easily be thrown into a front-of-house rack, especially as the unit can double up as an emergency line-level delay.

The front panel is simple to use, with four buttons that do the business. There's a button that allows you to input the required delay in feet, metres, or milliseconds; two buttons that increase or decrease the delay setting; and a bypass button for switching the delay in and out. Two headphone outputs are also fitted, with both 6.5mm and 3.5mm stereo jack sockets. These are in parallel, so if you do need to plug in two pairs of headphones there is a reduction in level, which is a shame. The Can-D is not a headphone amp as such, but is designed to give out the same volume level as is input. The output power is 325mW into 70Ω, with a total distortion figure of 0.010 percent, which was powerful and clean enough to accommodate all the headphones I tried, although I did find my 400Ω Beyer DT100s a little quiet. LA Audio have thought carefully about headphone impedance issues, as headphones can differ dramatically, allowing you to attenuate up to 80dB on the Can-D output, where required, for low-impedance cans. The Can-D offers a flat frequency response from 20Hz to 20kHz, close to the +/-0.1dB claimed in the manual. When I introduced a 10ms delay on the unit, I measured a 10ms delay on my test software, and this accuracy held true for all the delay times I tried.

One slight oversight is that when you set a delay in metres the Can-D assumes that one metre equates to 3ms of delay, but this figure should really vary depending on atmospheric conditions such as temperature and humidity. It would be nice if it was possible to input these variables and have them compensated for automatically by the Can-D. This ability is pretty standard in most PA management systems, but its omission in the Can-D is nothing that can't be rectified with a little manual adjustment. I assume that the designers were just trying to make the unit as simple as possible to use, which is no bad thing. Another small oversight is the lack of an input-level clip LED to help you ensure you're not overloading the unit.

Verdict

In use, the Can-D proved to be a very useful tool, and although it's not cheap, it is very well built. While I was mixing front-of-house at various venues, it provided me with a very coherent sound in headphones that I hadn't achieved before. For both light orchestral reinforcement and louder rock concerts, I found I could run my headphones quieter, as I was no longer competing against the PA to hear, which should help reduce the risk of hearing damage. In all, the Can-D is a good, compact little unit that does exactly what it was designed to do.