For almost as long as audio equipment has been built to fit the EIA standard rack size, some manufacturers have built “half rack” units that fit in one half the width of a rack space (up to 3RU high). Although this practice had a peak of popularity in the 1980’s for consumer-musician effects and processors, there has been a resurgence of this format in the high end recording equipment world in recent years. Some of the finest brands make half-rack gear.
But how the devil do you mount them in a rack?
Yes, you can buy generic rack shelves with an array of screw mounting holes, but in my experience these almost never work. First and biggest problem: height. By the time you have attached your half-rack unit to the shelf, very often it is slightly taller in total than 1RU. And even in cases where the mounted unit is not too tall above the shelf, very often the mounting screw heads on the bottom of the shelf protrude too far. In either case you can’t fit other rack units above or below it without damaging them. Second problem: sometimes there are no tapped screw holes in the base of the half-rack device. So how are you supposed to attach it to a shelf? I have used double-sided tape, but the thin stuff doesn’t hold well, and the thick foam tape always makes the mounted device taller than 1RU. Plus I have had a very difficult time trying to remove leftover adhesive residue from both kinds of tape, after un-racking the device.
Individual brands sometimes make and market a special mounting system for their own devices, but in every case these systems only work if you have two half-rack units from the same brand. If you want to rack a preamp from one brand with an EQ from another brand, you’re hosed. And there are a surprising number of manufacturers that don’t even bother to make a mounting system for their own half-rack units.
In the short term, there is no practical solution. In the long term, here’s what I want to see: manufacturers should design their devices so they will be easy to mount in a rack without exceeding the standard rack height by even 1 mm, on either the top or the bottom. Manufacturers should be alert to these practical considerations in every product they design, and they should ensure that customers will not be frustrated by the most basic use of the equipment. Designers! Your products do not exist in a vacuum, they have to interface well with other brands’ products, and they have to FIT!
In a perfect world, I’d like to see some standardization, please! The EIA rack unit has been a terrifically successful model; why not extend that success to the half-rack width? How hard could it possibly be to design half-rack modules to use the same screw-on rack ears and center connecting plates across brands? I’ll tell you now, it would not be difficult at all, and in fact that standardization would be a cost savings for design teams! In equipment manufacturing, the more standard non-proprietary parts you can use, the less expensive the product is to manufacture. Combine that with the assured increase in popularity of the goods once they are no longer hellishly frustrating for the average consumer to use, and it’s a solid home run for everyone involved. The half-rack module format has been around for decades, and it doesn’t appear to be going away. So manufacturers, take the next step and make it work well!
To consumers looking for advice on the best way to mount your half-rack gear, I have only two suggestions: either buy two products from one brand, to mount together with that brand’s proprietary racking system, or give up entirely.