Quick Patch Cables for Around the Shop
It’s a recurring story. You need a point-to-point patch cable to temporarily connect Product A to Product B, but you don’t have one with the correct connectors. If these are professional audio products the inputs and outputs should be balanced. This means that only a twisted-pair is required to make the connection. Sure, you have spools of “mic cable” (shielded twisted-pair) but dealing with the outer jacket and shield takes time. You can get hooked up much faster by making your own twisted-pair patch cable from hook-up wire.
“Hook-up wire” is an insulated single conductor. It is often used for short point-to-point connections within components, racks, electric guitars, etc. A little trick I have used for years is to twist two different colors together to make unshielded twisted-pair (UTP) cables. Just play out a few feet and fasten the ends in a vice. Fasten the other ends in a battery-powered drill and twist as tightly as you please – the tighter the better.
I recently discovered a really nice vintage push-back wire designed for use in electric guitars.
From the website: 22 AWG unshielded single conductor wire is tinned and stranded, with a white celanese wrap and waxed braided cotton outer insulation. The cloth insulation simply pushes back to expose the center conductor wire.
Since it is both stranded and tinned, two strands can be combined to form an especially tight twist that doesn’t untwist itself due to memory effect. For soldering to connectors, just push back the insulation – no stripping required.
Don’t get nervous about the cable not having a shield. For balanced, line-level signals (>1 Vrms) the shield plays a secondary role to the twisting with regard to interference immunity. In fact, it can actually make things worse by producing ground loops between the products. By eliminating the shield we have saved a lot of fabrication time without compromising the integrity of the interface. pb
Photo Below – The twisted-pair is tight and retains its shape, right up to the connection point.