Graham Slee Spatia Speaker Cable

Graham Slee Spatia Speaker Cable

You owe it to your amp and speakers!

Music consists of rapid changes in asymmetrical waveforms which due to capacitance are remembered by cables and confuse the spatiality, upsetting the sound stage and often altering tonality.

The Spatia is a low memory speaker cable. The two wires of a speaker cable are in-effect two drawn out metallic plates with insulation separating them - the equivalent of a capacitor.

Cables are very much like capacitors where the insulation which spaces the plates apart is known as dielectric - a scientific way of saying insulation - the insulation between and surrounding the plates.

Dielectric quality affects how quickly a capacitor can 'forget' its charge and swap direction to the next charge. Music being comprised of rapidly changing complex asymmetrical waveforms at multiple frequencies all at once (bass notes included) will be distorted and highly coloured if the cable dielectric isn't fast like the Spatia.

And because you read so much about speaker cables you know other manufacturers are preoccupied with everything but dielectric quality - that is if they've ever heard about it?

Therefore you know the Graham Slee Spatia is already something special.

Dielectric quality could also be affected by lay direction and the Spatia subtly suggests to the user the direction of best subjective results under its braided covering. The unobtrusive blue marker goes to the amp end.

At only 80pf per metre its low capacity makes it safe for use with really fussy amplifiers!

Damping Factor, Characteristic Impedance And Cable Losses

People can get overly concerned about damping factor and how a cable can affect it. They are also easily convinced that characteristic impedance robs speaker voltage, but does it?

Damping factor is supposed to tell us how much control the amplifier has over the speaker cone. If the amplifier sends a single polarity pulse to a speaker cone, the explanation insists that the cone will want to bounce and spring in the opposite direction. A good damping factor is supposed to prevent this. That suggests that whilst the amplifier is on with no signal applied, the cone is held stiff, but that is not the case: slight finger pressure on the cone will move it.

Amplifiers with negative feedback have extremely low output impedance, that is not to say they can drive extremely low impedances, no, output impedance refers to their driving or "source" impedance.

Cone bounce, being no part of an amplifier's signal, can overcome, or use up all the amplifier's negative feedback (which is really there for reason of reducing distortion and noise), and hence the amplifier's output resistance, which is much higher, can dominate the output impedance. And in amplifiers claiming zero negative feedback the output impedance equals the output resistance, period.

In solid state amplifiers the output resistance is equal to the amplifier's emitter (or source if FET) resistor value (plus the output device's intrinsic resistance), and is often between 0.1 and 1 Ohm. In a valve amplifier it is the driving impedance of the output transformer secondary, which is within a similar resistance range.

It is debatable whether damping factor actually exists or is just an imagined hi-fi "invention".

Characteristic impedance is the resistance the cable would exhibit if the cable were infinite in length, so if a speaker cable were to have a characteristic impedance of say 80 Ohms, the speaker connected to it at this imaginary infinite distance - forever away - would see gross attenuation and receive only 1/10th of the amplifier's voltage.

In reality, your speakers aren't going to be forever away - they're going to be between 2 to 10 metres away in most domestic applications, so the characteristic impedance is of no consequence. The resistance between the amplifier and the speaker at audio frequencies, and quite a bit beyond, will simply be the DC resistance of the wires in the cable.

If you consider all the above, a cable resistance in the region of your amplifier's output resistance (as opposed to output impedance) is going to be perfectly adequate.

For our Spatia speaker cable the sum of feed and return wires is approximately 0.04 Ohms per meter. 10 metres contributes 0.4 Ohms. That's perfectly adequate, unless you're running a big stage PA rig!

Specification

A high speed high voltage low memory cable designed for DC to high frequency use including the audio spectrum

• Available terminations: 4mm plug; 8mm spade
• Connector plating: Gold
• Voltage rating: 1,000V max
• Test voltage: 4,000V
• Bend radius: 30mm/1.25"
• Conductors: Fine bare copper
• Core insulation: Special compound
• Jacket: PVC compound
• Braid: PVC
• Suggested Direction: Marked blue under braid to source end
• EC directive: to ECD 73/23/EEC