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Radial Engineering SGI Studio Guitar Interface

I know I'm not the only person around who has tried the old 100-foot guitar cable trick.

I know I’m not the only person around who has tried the old 100-foot guitar cable trick: You know, the one where you run the really long cable from the guitar player in the control room to the live room (or iso booth) where the amp is. Like me, you’ve probably noticed that it doesn’t work very well; you get lots of hum and other noise or the guitar player remarks on the “dead” feeling of his normally lively rig. Enter the Radial Studio Guitar Interface (SGI) system ($300 list).


The SGI is a two-part solution comprising the SGI-TX transmitter and the SGI-RX receiver. Built to Radial’s extremely high quality standards, both are very heavy yellow boxes, like steel bricks. The SGI-TX requires power from the included wall wart adapter, and, like some of the other Radial guitar-oriented boxes, there’s the somewhat-enigmatic Drag control. Don’t worry, you won’t be wearing a skirt if you turn it up; instead you’ll notice some pleasing tonal variations that allow you to darken the tone and change the “feeling” of the guitar/amp interface through some impedance-matching mojo. The passive SGI-RX has an essential ground lift button.

In Use

Operation couldn’t be easier. Plug into the TX’s input fromyour guitar (or bass) with a standard 1/4-inch instrument cable, connect an XLR microphone cable between the TX and the RX, find your signal in perfect condition at the output of the RX, and plug into your amp — done. For this review, I used a 50-foot Gotham GAC-3 mic cable and the excellent Vovox Link Protect A (5- meter length) for the instrument cable.

Radial claims that the SGI can drive up to 500 feet of balanced cable. Being the natural skeptic that I am, I decided to give it a try. In a happy coincidence, I had just constructed 10 50-foot mic cables using Gotham GAC3 cable and Neutrik XLR connectors. So, I set up the SGI-TX in my control room, plugged in my 1980 Les Paul and connected the output of the RX into a Polytone Mini-Brute closemiked with a Violet Design Amethyst Classic condenser mic.

There was virtually no difference between the sound of 50-foot and 500-foot lengths of cable (as well as the intermediate lengths). That’s not to say that there was no difference between a straight 15-foot cable right into the amp and the SGI chain; there was a slight attenuation in volume, and a minor tonal shift. All in all, the difference between the two setups was extremely minor, and only noticeable if you were listening for it. The Drag control further narrowed the gap.

Already impressed, I tried the same setup with a FBB Custom fretless bass loaded with a single Bartolini Humbucker and an active onboard preamp to see how the SGI coped with an active instrument. As expected, the SGI sounded great and proved to be a useful addition to the session.


As has been the case with other Radial Engineering products I have used (and purchased) in the past, the operation and build quality of the SGI system was literally without fault. Highly recommended!

Contact: Radial Engineering | 604-942-1001 |

Richard Alan Salz is a producer/engineer and founder of Vermont Audio