The TNT Hydra

a cool DIY mains distribution plug!

Product: TNT-Audio Hydra mains distribution plug
Manufacturer: Not for sale, do it yourself!
Approx. price: 15 - 20 $ (depending on cable lenght and type)
Author: Geoff Husband

You've all heard it..."the best cable is no cable at all". Apart from being one of those smug comments hi-fi reviewers come out with, it's also rather a stupid comment seeing that even Zen Buddism isn't going to light up those amps unless they're connected to the National Grid... Or so I thought.

Unless you're one of those people who've rewired your house with half a dozen double sockets for the hi-fi (think of all those screw connections there...) you'll have to use a mains "gang socket" of some kind.
The cheap versions of these can cost as little as 10 pounds but most have two big failings. First the links between plugs are a mass of rivets and wafer thin brass track, and secondly they nearly always have an LED to show they're plugged in, happily chucking out RFI into your system, if you're really unlucky they'll have a switch...

There are some classy gang sockets on sale specifically for hi-fi use. These lack the lights and switches of lesser items and the tracks are made of better and thicker material.
They also come equipped with decent quality cabling to join them to your wall socket - these things start at about 100 pounds and rise into seriously silly money thereafter. But I have found something much more purist and at a fraction the price...

The heart of the Hydra is the Micromark Multi-Way Mains Plug. This is so delightfully simple, it makes you want to smile. Being simple it costs 6.99 pounds (10-12 US $) from Maplin (order code VD 02C).
All it is, is an oversized plug which accepts four cables. So instead of a length of cable and then a complex terminal and track system in a gang socket, here we have a direct connection to the three mains pins for the four sets of earth, live and neutral leads.
Where each set of cables is attached is a substancial "buzz bar" so no skimpy tracks, and because each component is connected within one centimetre of the next you get the nearest thing to perfect star earthing short of cramming all the wires into one plug.
The plug will take up to 3,120 Watts (officially) it should cope with most things you throw at it... In one stroke you eliminate at least two connections, a length of cable and all the internal tracks of a gang socket - Believe me if this were marketed as a hi-fi component it'd be gold plated, come with assorted technobabble and cost 100 pounds.

To complete the Hydra simply fit the mains wire of your choice to each connection and leave sufficient cable to reach your hi-fi :-) There are several cable designs on TNT to choose from. In my case I wired my pre-amp power supply and the two monoblock Audion valve amps to three of the vacant holes, then used the other to wire in a standard gang socket for the rest.
If I didn't have to swap components all the time when reviewing I'd not do this. If you have a double wall socket then two of these plugs will fit side by side to give eight mains leads - brilliant!
I made up leads each with three lengths (live, neutral and earth) of 1.5mm solid core mains wire, plaited a la Kimber. A four foot length of each gives enough RFI attenuation.
If using this cable I find it best to connect all the individual wires, 12 in all, to the plug and then plait them into the four cables.
Girls are born knowing how to do this - boys - just ask the nearest female... The insulation on these cables is quite soft and vulnerable, it is essential that you protect it in some way, with heat shrink, tape or woven plastic cable outer.
Then just fit the end terminations, IEC etc. The result is neat and makes tangles a thing of the past.
The internals of the plug are very well laid out and of excellent quality so wiring up is easier than with most mains plugs, the only weak point is the fuse holder which is riveted on.
A dab of solder will help hold this connection long term...
The biggest drawback is that it's a British standard plug. Adaptors are easily available, but for those out of Britain I'd have thought one British double socket dedicated to the hi-fi would be well worth the effort - certainly better than the ghastly French plugs I have to put up with!

Chez nous the immediate result was the tidying of the cabling of my system, but with it came a general increase in clarity over the old gang socket I had been using. It's not earth shattering but certainly greater than fiddling with interconnects, in fact for an outlay of 20 pounds or so it could be the most cost effective upgrade you ever make.

Warning: Electricity can kill. If you end up as a blackened char on the end of a screwdriver you've only yourself to blame, you should have got a qualified electrician to do it...

© Copyright 2000 Geoff Husband - http://www.tnt-audio.com