Hi Dec

 

Your Mark Twain quote in this weeks 'one minute' rang a bell. This is a true story. Some years ago I worked with a guy who sold franchises (priced around £20,000). He was very very good at it. One day he told me how he did it. Firstly he said I look at their CVs, their experience in this trade, their financial status. I look for any fault or negative I can find. Then I tell them they can't have one. Works a treat. They are then put in a position of having to convince me to take their 20 grand!!

 

Good innit.

John

 

I always look forward to hearing from Ian Warrener.  He joined our 'Serious Writers Guild' and since then started his own P.A. design Company.  He custom built monitors for my studio which I must say are 'AWESOME'.  I have learned so much from Ian about the 'black art' of speaker design and the technology involved in great speaker reproduction.  Just listen to what he says about the basic idea of connections:

A basic check that could save MAJOR PROBLEMS

A major cause of problems in any system can be cured quickly and easily! How?

By checking all cables regularly!

Cables and connectors are probably the single biggest cause of problems in a system.  Often these faults can intermittent and so difficult to trace. An old solder bucket can create noise and disconnection. A loose or badly designed cable retention system will put undue pressure on the joints and as wires become loose partial disconnection's can cause intermittent faults and dangerous short circuits.

As far as signal cables are concerned, wherever possible balanced, shielded cables should be used. They cut down induced noise and can increase overall levels dramatically. XLR connectors are my preference and I always use I.D.C (insulation Displacement Connection) rather than solder buckets, they work by cutting through insulation and trapping wire, suffering less over time and with use. I also use gold pin versions for the best signal path possible but standard pin are still much better than jacks or RCA phono’s. And it has to be said, Neutrik’s cable retention system is probably the best although Amphenol are close, with an easier assembly IDC unit.

Always specify gold binding posts:

These days, other than bare cables onto gold binding posts, I feel Neutrik speakon’s are the only way to terminate loudspeaker cables; High capacity and self cleaning, they offer a twist lock bayonet system to prevent accidental removal and are available in many alternative formats.

Onto the speaker cable, the bigger diameter of the conductors, the lower their overall resistance (over the same length), the better the performance of the system due to lower losses. The best conductors are made from 100% oxygen free copper (OFC), providing much improved conductivity over time and reducing signal losses still further.

The insulation should be flexible to avoid breakage and high capacitance to reduce induced signals (‘crosstalk’ from parallel cables) especially where long runs are used. Rubber is to be avoided as it degrades too quickly when exposed to humidity and sunlight, so various polyethylene and polyvinyl compounds are used giving greatly extended cable life.

Signal loss table:

Just Email me to receive a cable loss table (courtesy of Crest).  It demonstrates just how much effect speaker cable conductor diameter has on the associated losses. Also note that losses double from 8 to 4 ohms, and double again at 2 ohms! (one more reason not to use 2 ohm loads).

One last quick note –

Remember each connection is actually at least 3 connections, often 5 (wire crimped to spade terminal, spade terminal to connector pin, connector bar to connector bar, connector pin back to wire). So by reducing connections you can improve overall signal integrity exponentially. This is yet another reason for wiring direct rather than via a patch bay if at all possible.

Feel free to forward any questions you may have and Ian will always do his best to answer them or give him a call on 01909474977 (U.K.) if he is not there he will get back to you as soon as he is (usually 24 hrs max)

And check Ian out at www.pa-direct.co.uk

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