DBX: CT-3 Cable Tester

Cables are the brakes of our “studio bus” – necessary to get anywhere and ignored until they malfunction. There are numerous ways to troubleshoot: continuity meters, known good connections, signal generators, or all-in-one testing boxes are all ideal for short-run, easily accessible connections. However, these can be unwieldy when you can’t access both ends with a hand-held tester.

The CT-3 looks like the familiar all-in-one checkers, but with a dbx logo. Looking closer, there are two 9-volt battery compartments and thumbscrews on the shorter sides. Why? Because the CT-3 can be separated into two units: send and receive. Wondrous!

Here is one example where my CT-3 has paid for itself. During a voice-over session, the mic signal wasn’t making it to the DAW. This chain had several elements: live room mic to input panel, panel to patchbay, bay to gear, and patch cords routing among components. Swapping cables is a reasonable option in a small studio, but with a client present and the billing clock running, any fix that takes longer than five minutes will interrupt work momentum and reduce our professional credibility. Placing the CT-3’s send module at the mic XLR and CT-3’s receiver where the signal enters the A/D, I continued testing until I found the offending component.

In this case, phantom power was not making it from the preamp to the mic. The defective cable was replaced, and the session was up and running. Total downtime: four minutes. The client barely noticed.

The CT-3 can work with common studio connectors such as RJ45, RJ11, MIDI, Speaker Twist, XLR, RCA Phono, BNC, DIN, TRS, TS, DMX, and Banana connectors. It has built-in adjustable tone and probe inputs for continuity testing. Inexplicably, there is no provision to test TT cables on the CT-3. Perhaps the DMX jack was a clue; this is designed with live sound in mind. When you want to use the CT-3 to send or receive through a patchbay, the easiest way is using a TT to XLR adapter cable but testing patch cords would necessitate building adapters using female TT-ports. By the time you make that, it would be just as easy to create a jig or reserve a few jacks on a bay for testing. TT arguments aside, I really wanted a tool for testing longer, installed connections, and the CT-3 provides rapid results, especially with a client staring over your shoulder.