The Helios Electronics Ltd One Console Module is a channel strip taken directly from a Helios console and used as a piece of outboard gear. This gives you the sound of a Helios console in a few channel strips, without the hassle or money it would cost of acquiring a full Helios One console. I don't believe that you can buy these on their own, as they can only be had if you take them directly from a Helios board. The studio that I work at has two of these in a rack made by Vintage King. An external rack and power supply will be necessary to rack up these units if you do have just the modules. The rack that we have them in contains XLR connections for mic and line input, as well as for your outputs. Whether it's rack mountable or not really just depends on what kind of casing you put it in.
The make up of the Helios Electronics Ltd One Console Module does have a decent amount going on, since the equalizer is very versatile. Either way, if you know something about the make up of a traditional channel strip, you should be able to figure out how to use this pretty easily. The preamplifier section of the Helios One has a line gain knob, as well as a switch for choosing between a line, mic, or a mic with a -20 db pad signal. The equalizer has three bands in total. The high frequency band is set at 10 kHz, with a parameter for setting your gain level. The mid frequency band has separate parameters for frequency and gain, as well as a switch to choose between peak or through. The bass frequency band has the same make up as the mid band, but without the peak/through switch. Lastly, there are switches for EQ cut/on, phase, and for a high pass filter which can be set at either 40 or 80 Hz. A manual isn't necessary, nor do I think you could find one.
The sound quality of the Helios Electronics Ltd One Console Module is outstanding all the way around. These Helios boards were used on many classic albums that everyone has heard for sure. Let's start with the mic preamp, which is great for recording just about anything. I've used it for a few different applications, including for vocals, percussion, and acoustic guitar. Without using the equalizer, it's got a very transparent sound that is true to the original source. The equalizer makes this one of the most versatile channel strips out there, as you can pretty much do whatever you want with it, which is rare for a three band equalizer, but this one has the flexibility. The EQ has a sterile sound, only making the moves that you ask of it.
While not too many engineers out there will have access to Helios Electronics Ltd One Console Modules, and if you do, you already know how great these sound. This is really a custom piece of gear if you don't have the original console, and even though there once were a lot of these consoles around, you won't find too much Helios gear out there anymore. These modules have their own sound and are a great color to bring to the table...