Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B11/00—Communication cables or conductors
  • H01B11/18—Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
  • H01B11/1895—Particular features or applications
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B11/00—Communication cables or conductors
  • H01B11/02—Cables with twisted pairs or quads
  • H01B11/12—Arrangements for exhibiting specific transmission characteristics
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/0009—Details relating to the conductive cores
  • H01B7/0018—Strip or foil conductors

Definitions

• This invention relates to audio cables generally and, more particularly, to a novel audio signal cable in which the geometry of the conductors therein and the dielectric which separates them has been arranged 0 to raise the capacitance and lower the inductance-of the cable, therewith lowering its characteristic impedance to the same order as that of the load, typically 2 to 10 ohns.
• the resultant loss of fidelity is espectially important in fast, transient signals which are impaired by a much slower rise time at the speaker than at the amplifier.
• several speakers are connected in parallel to the same cable, further lowering the load and enhancing the impedance mismatch.
• the result is severe HF ringing.
• twin lead cables are relatively open to neighbouring fields because of the distance between the conductors.
• the effect of this may be overplay between channels when cables are routed together, or line frequency hum picked up from adjacent power wiring.
• the kind of effects described may be avoided either by extensive cable shielding or separate routing, but either measure often adds considerably to installation costs.
• the present invention deals with improvements in speaker cables by virtually eliminating the problems outlined in the above.
• cables according to the invention are more compact and easier to install and conceal than conventional speaker cables. Due to their construction, however, special measures are required for termination and splicing which may be facilitataed by the use of specialized hardware, one embodiment of which will be described in the following.
• Speaker cables according to the invention have a low characteristic impedance, typically under 10 ohms, effectively excluding signal distortion from impedance mismatch.
• they are virtually immune to neighburing fields and may be bundled or routed next to power lines without the effects described above.
• this can be achieved by exchanging the conventional conductors in a cable with wide bands composed of solid foil or strip or"a multitude of closely juxtaposed wires of conductive material.
• a preferred embodiment of a twin cable according to the invneion may consist of two such bands sandwiched close together with a thin interlayer of a suitable dielectric material like, e.g., polyester film, and surrounded by a common sheath of suitable insulation.
• the effect of this construction is a drastic increase in capacity and a simultaneously reduced inductance, compared to conventional cables, which together bring along the desired reduction in characteristic impedance.
• the cable is virtually immune to outside fields and the emmission of low frequency magnetic fields, which some people consider a health hazard, is virtually eliminated.
• Figures 1, 2, 3 and 4 are embodiments of cables according to the invention.
• Figures 5, 6 and 7 are comparative measurements on conventional heavy gauge, twin lead speaker cable versus cables according to the invention.
• FIG 8 a clamp, also according to the invention, allowing convenient termination and splicing of the special flat speaker cables of the invention.
• elements 1 and 2 indicate flat strips of a conducting matrial, e.g., copper or aluminum placed on each side of a somewhat wider, interlayer 3 consisting of a dielectric material, e.g., polyester film.
• the dimensions of the strip depend on system requirements but a good example for audiophile application would be copper strip 0.375" wide by 0.010" thick, yielding almost the same conductive cross section as the 12 gauge wire now being used increasingly in residential stereo systems.
• the cable of Figure 1 is the simplest embodiment possible of a cable according to the invention, having no external insulation at all.
• Figure 2 is another embodiment of a cable according to the invention wherein the separating film
• FIG. 3 has been folded or cuffed around the edges of one of the strip conductors and a second film strip 4 folded around the entire sandwich, either leaving an area of one conductor open or enclosing completely the two conductors 1 and 2 and the separating film 3.
• the film layers referred to in the above can be replaced by, e.g., extruded insulation, still within the scope of the invention.
• Figures 3 is a construction similar to the one shown in Figure 2, the only difference being that the solid bands 1 and 2 are exchanged with bands of closely juxtaposed multiple wires. This cable can be terminated in the conventional manner by stripping and twisting the wires of each lead in turn. —
• Figure 4 is a cable according to the same basic principle utilizing even wider, band shaped conductors which have been folded lengthwise and arranged in a mutually interlocking relationship, the objective being a further reduction of characteristic impedance combined with ease of installation through the reduction in width of the assembly.
• Another variation would be forming the cable into an elongated hollow tube, or the use of tubular conductors arranged concentrically surrounding a core of a filler material or air.
• the characteristic impedance of the cables referred to in the above will depend largely on the width of the conductors and their mutual distance as well as the dielectric constant of the material of the interlayer. For example, using solid conductors 0.375" wide and an interlayer of 0.003" thick polyester film will produce a cable having a characteristic impedance of approximately 4 ohms.
• Figure 5 illustrates comparative measurements using a 12 KHz square wave transmitted via I, a 25 foot long cable according to the invention with a charactieristic impedance of 4 ohms and II, an equally long cable of conventional construction with 100 ohms characteristic impedance, both connected to a 4 ohms load.
• A is the signal at the amplifier and S the signal at the speaker terminals.
• II indicates a clear leading edge spike at the amplifier and significant distortion at the speaker terminals.
• I in contrast, is entirely distortion free, showing only the resistive loss en route.
• Figure 6 is the same set up with a 2 ohm load, indicating aggravated distortion at both amplifier and speaker in the case of the conventional cable and " no distortion with the new cable.
• Figure 8 is a preferred embodiment of a clamp suitable for termination and splicing of cables of the invetnion and comprising a non-conducting body 5, e.g., injection molded from a suitable thermoplasic, with a slot 6, somewhat wider than the cable, and a metal strap 7, having holes 8 and 9, threaded to accept screws 10 and 11, and a metallic insert 12, fitting in a depression 13 located at the bottom of slot 6.
• the strap and insert are each provided with sharp projections 14 facing each side of the cable 15 in turn as it is placed in slot 6.
• a short length of conventional cable is used for hook up to speakers and amplifier.
• the clamp is suited for termination at either end, or at any point along a calbe according to the invention, and for splicing two cables together, with or without simultaneous termination.
• Screws 10 and 11 are loosened and the cable 15 is inserted into slot 6 from one or the other side of the clamp, or one screw is unscrewed and the strap 7 opened and the clamp hooked onto the cable for midway termination.
• the hook up wire is stripped and one lead 16 inserted in the hole to emerge behind the insert 12, while the other lead 17 is guided around screw 10 just behind its head.
• strap 7 will make contact with one side of the cable, cutting through any external insulation-,- and, at the same time, contact will be established between strap 7 and one of the hook up wires via screw 10.
• the insert 12 will establish contact between the opposite side of the cable and the other hook up wire, and the termination is completed as the screws are tightened home.
• the clamp described can also be used for splicing two cables together as they are inserted from either end with their ends not touching each other inside the clamp.
• mutual contact is established via the dual projections on the strap and the insert respectively, and a simultaneous termination can be carried out by means of a hook up wire if desired.
• Most manufacturers of audiophile signal cable emphasize the importance of a very low capcity per linear unit and it is a very significant characteristic of the new cable that the capacitance may be, e.g., 100 times higher than in other cables.
• the impedance of the distributed capacitance and inductance cancel each other out and the result is a cable appearing to the amplifier as a purely resistive load. This fact is amply evident from the oscilloscope pictures which indicate a total elimination of both "kickback" to the amplifier and distortion at the speaker terminals even in the case of the 1:2 mismatch ratio illustrated in Figure 6.

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• Communication Cables (AREA)
• Manufacturing Of Electrical Connectors (AREA)
• Insulated Conductors (AREA)

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Applications Claiming Priority (2)

Publications (1)

Family

ID=21860865

Family Applications (1)

Country Status (8)

Cited By (1)

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Citations (3)

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• 1993
  • 1993-03-15 US US08/031,687 patent/US5393933A/en not_active Expired - Fee Related
  • 1993-09-03 TW TW082107228A patent/TW266298B/zh active
• 1994
  • 1994-03-15 AU AU62188/94A patent/AU6218894A/en not_active Abandoned
  • 1994-03-15 EP EP94909280A patent/EP0689716B1/en not_active Expired - Lifetime
  • 1994-03-15 DE DE69405381T patent/DE69405381T2/de not_active Expired - Fee Related
  • 1994-03-15 CA CA002158250A patent/CA2158250C/en not_active Expired - Fee Related
  • 1994-03-15 WO PCT/IB1994/000053 patent/WO1994022148A1/en active IP Right Grant
  • 1994-03-15 JP JP6520853A patent/JPH08507897A/ja not_active Ceased

Patent Citations (3)

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