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Page updated: 1-Sep-2010

Audio Wiring

Audio wiring seems quite innocuous at first, but as you add more gear you start to realise that its weight when multiplied up is a force to be reckoned with.
Wires unplugged    More wires unplugged

You can use compact multi-core looms or go fully digital with a computer, but if you want to stick with analogue and use individual wires then this clamping system may give you some ideas:-

Back of rack    Small mixer

Racks can now be moved around for maintenance without plugs falling out!

Details

The basic method is to clamp the wires in groups to the horizontal rack bars (in my case, QuikLok racks) using short metal plates, each fastened with a couple of bolts.

Metal clamps

Future expansion is catered for by standardising the plate size and pre-drilling more holes in the racks than are needed. Once all the gear is in place, drilling extra holes is not recommended: electronics + swarf = expensive repair bills.

The number of wires per group needs some thought; you don't want too many as they'll all go loose when the bolts are slackened, making maintenance tricky. If you have too few, then you need more clamps and hence more 'wasted' space at each end for the bolt holes, and as discovered later, there's less space than you think.

8 wires per clamp seemed a sensible number as mixers & recorders tend to group tracks 8 at a time, so the plate length was defined by (8 x wire diameters) + (2 x bolt holes). Wires with different diameters such as midi, mains etc. should be grouped separately, so you may get more or less than 8 per clamp.

Measuring the rack width for items requiring the densest wiring (mixer, patch panel rack & multi-track recorder rack) showed that a row of simple clamps would not hold enough wires, so I lengthened the bolts to allow for a double-sided option, with a plate top and bottom of the rack bar fastened by a single pair of bolts; these would hold up to 16 wires each.

It's essential that the plates grip all the wires equally without flexing; I erred on the safe (overkill?) side and went for 6mm steel. I would also recommend using wing-nuts if possible; I had to use a spanner with my earlier setup as the unbalanced wires had a waxy, slippery outer coating, but the new balanced ones have a rubbery surface so the nuts only need to be finger-tight.

The final size of each plate was 75 x 25 x 6 mm, with holes 60mm apart. This meant the 19" racks could hold up to 5 horizontal clamps per bar. The bars on the mixer & keyboard stands were also pre-drilled to allow for vertical clamps using shorter bolts (shown later).

Results

Here's the back of one of the racks showing a few single-sided clamps. Mains wires are clamped separately and kept to the sides of the racks; by using daisy-chained 4/6-way adapters strapped to the vertical bars, there's only one mains feed for each rack:-

Back of rack     Back of rack

A close-up of a mains clamp (left), and double-sided clamps (right). Spare holes allow for adding more clamps in the future:-

Single clamp close-up    Double clamps close-up

Multi-track recorder

A more densely-packed rack clamping 24 inputs & 24 outputs:-

Multi-track recorder

Large mixer

The back of the large mixer (below, left) used to be a nightmare, but now the wires drop down and are clamped to the mixer stand's horizontal support bar (right), this time using plates on either side of the bar instead of above & below.

Large mixer sockets    Large mixer clamps

View from under the mixer looking up towards the back showing the other side of the double-clamps:-

Large mixer rear clamps

Small mixer

The clamps for the small mixer also make it easy to disconnect for location recording:-

Small mixer    Small mixer

Keyboards

The shorter bolts were also used for the horizontal bar behind the keyboard stand:-

Keyboard

Patchbays

Extra horizontal bars (25mm square tube) were added as the standard QuikLok rack only comes with one, and I wanted one bar for each patch panel. Each panel has 48 wires, so 3 double-clamps holding 16 wires each were used per bar. This leaves enough space (only just!) to get your hands in and also allows for the odd extra clamp or two for cables with different diameters.:-

Patchbay front    Patchbay front
Patchbay rear    Patchbay rear

Close-ups of the 25mm square tubing; the two vertical sections are bolted to the rack frame sides, and the horizontal pieces are then bolted to these:-

Patchbay clamps close-up    Patchbay clamps close-up    Patchbay clamps close-up

A few patchbay lessons learnt

  • If you can only access the patch panels from the rear, leave more vertical space between the bars than I did for getting your hands inside!
  • Better still, plan your layout so the patch panels are at the top of the rack and make the lid removable, then you can access the wiring from above. The QuikLok lids are normally bolted from below, so I replaced the bolts with some threaded studs (e.g. cut the heads of some old bolts). These screw into the lid and then rest/locate in the original bolt holes on the rack frame top.
  • If you intend putting heat-producing gear below the patch panels, add a shelf to prevent dust being drawn up into the sockets.
  • Keeping track of what wires go where is easier if you match top & bottom clamps with their corresponding panel jacks, e.g. outputs on top and inputs below.