WO2020218935A1

WO2020218935A1 - Method for reducing the inductance and wave impedance of a transmission line and audio cable

Info

Publication number: WO2020218935A1
Application number: PCT/RU2019/000285
Authority: WO
Inventors: Александр Геннадьевич ПОПОВ; Владимир Иванович ПОПОВ
Original assignee: Александр Геннадьевич ПОПОВ; Владимир Иванович ПОПОВ
Priority date: 2019-04-22
Filing date: 2019-04-22
Publication date: 2020-10-29

Abstract

A method for reducing the inductance and wave impedance of a transmission line consists in the parallel connection of two-wire transmission lines, wherein two-wire transmission lines are arranged consecutively one after the other such that the forward wire of each subsequent transmission line is arranged downstream of the reverse wire of the preceding transmission line and, accordingly, the reverse wire of each subsequent two-wire transmission line is arranged downstream of the forward wire of the preceding transmission line. An audio cable for implementing said method comprises a plurality of substantially flat insulated conductors, each of which consists of two or more contiguous metallic strands laid in parallel in rows inside extruded insulators. A portion of the plurality of conductors forms a forward wire of the audio cable, and the other portion of the plurality of conductors forms a reverse wire. The extruded insulators having parallel rows of conductors are mounted end-to-end in immediate contact with one another such that in each row of conductors the conductors pertaining to the forward wire of the audio cable alternate with the conductors pertaining to the reverse wire.

Description

Method to reduce inductance and characteristic impedance of transmission line and audio cable.

Scope of invention

The present invention relates to electrical signal transmission lines, preferably audio cables, as analog signal transmission lines.

Description of the prior art

A known method of reducing the inductance and wave impedance of a transmission line by parallel connection of two-wire transmission lines (twisted pairs of wires) disclosed in the book Ed E. Reference manual on high-frequency circuitry [1] pp. 22-23.

This technical solution is taken as a prototype of the method.

The disadvantage of the prototype is that the inductance and characteristic impedance of the transmission line decreases in proportion to the number of connected two-wire transmission lines. For example, to reduce inductance and characteristic impedance 10 times, 10 two-wire transmission lines will need to be connected in parallel.

The proposed invention eliminates this disadvantage of the prototype: the number of parallel-connected two-wire transmission lines is significantly reduced to achieve the required reduction in inductance and characteristic impedance of the transmission line.

Let us explain the purpose of reducing the inductance and characteristic impedance of a sound cable. An audio cable (loudspeaker cable), like an analog signal transmission line, operates at the frequencies of the electrical signal in the audio range (J = 10Hz 50kHz). In the technology of transmission lines, such a line is considered "short": I "I, where / is the length of the line, I is wavelength (l = 2nf). Therefore, to assess the influence of the transmission line on the signal, they are limited to analyzing the equivalent circuit from the lumped parameters of the transmission line: inductance L, active resistance r of the load Z _H connected in series, and capacitance C of the load Z _H connected in parallel. But in the case of matching the "short" line with the load, when the characteristic impedance (characteristic impedance) Z _{n of the} line is equal to the impedance Z _{H of the} load (acoustic system), it behaves like an infinitely long line, without signal reflection from the load. Despite the presence of imaginary resistances from the inductance L and capacitance C distributed along the line, the characteristic impedance Z _n = jL / C is the actual resistance (see [2] p.185-188, [3] p.466-468). All the power from the amplifier, if we do not take into account the small losses in the impedance of the line, is absorbed by the load. The amplifier is loaded only by the impedance Z _{H of the} load, as if there were no transmission lines. Consequently, there is no distortion of the transmitted signal. On the oscillogram for Z _{n, the} test rectangular pulse has no distortion at the load (see the oscillogram of FIG. 1 given in [6]).

When there is a mismatch, such as Z _h > Z _H , typical for audio cables, the input impedance of the transmission line

where L _p is the "mismatch" inductance. That is, the line manifests itself as a frequency-dependent inductive reactance up to Z _H = 0, (short circuit of the line end) (see [3] p. 471). The magnitude of such an inductance "mismatch" L _{p is} the greater, the greater the mismatch and the greater the inductance L of the line. Calculation of the input impedance Z _{BX of the} equivalent circuit from lumped parameters and measurement of the impedance of the audio cable with different loads showed that for Z _n = 1, 1Z _H inductance “Mismatch” I _p = 0, 181, for Z _h = 2 Z _H inductance L _p = 0.75 L, and for Z _n > 10Z _H inductance L _{p “} L. On oscillograms for Z _n > 2Z _{H, the} test rectangular pulse has“ collapse "of the leading edge and" pulling "the trailing edge of the pulse exponentially, characteristic of a circuit of series-connected inductance and resistance, (see the oscillogram of FIG. 2 given in [6]).

The well-known expert in the field of electroacoustics I.A. came to the conclusion that a sound cable should have a minimum inductance, in contrast to the popular opinion that for correct sound reproduction, a sound cable should have a minimum capacity. Aldoshin. In his article “Loudspeakers, part 7”, based on the representation of the equivalent circuit of the transmission line as a second-order low-pass filter, I.A. Aldoshina analyzed the amplitude-frequency characteristics (AFC) of the voltage of commercially produced audio cables with an active load of 1 ohm. Only one audio cable with the smallest linear inductance out of 12 investigated cables had a flat frequency response in the audio range and a characteristic impedance Z _L ~ 7 ohms (estimated from the diagrams given in the article). Characteristic impedances of 10 out of 12 cables are in the range from 32 ohms to 210 ohms [4].

If Z _l <Z _{H the} line manifests itself already as a frequency-dependent reactance of a capacitive nature up to Z _H = oo, (no-load of the line end) (see [3] p. 471). In this case, on the oscillogram, the test rectangular pulse has aperiodic surges at the leading and trailing edges, which, with a significant mismatch, turn into damped high-frequency oscillations at the natural resonance frequency of the cable (in the case of an active load) or at the resonance frequency between the cable inductance and the load capacitance, which may already be in the high-frequency part of the audio range.

Both variants of the mismatch Z _n > Z _H and Z _h <Z _H lead to a violation of the fidelity of sound reproduction. But if the first option is a consequence of an erroneous approach in the design of an audio cable, then the second manifests itself when the audio cable is matched with an acoustic system having significant impedance unevenness in the reproducible frequency band (see, for example, [4], which shows the dependence of the impedance modulus on the frequency of a 3-band speaker system, which ranges from 5 ohms to 25 ohms, with a nominal impedance of 15 ohms at 1000 Hz.).

Let us summarize the above.

To reduce the distortion of the signal introduced by the audio cable, you need to strive to match it with the load. The loudspeaker (acoustic system) has an impedance module Z _H from 2 to 16 ohms (as a rule, | Z _h | = 8 OM). Therefore, the main requirement for an audio cable is the equality of the characteristic impedance Z _h and the impedance of the loudspeaker Z _H , for example Z _L = | Z _H | = 8 ohms.

To expand the permissible mismatch of the impedance Z _{L of the} audio cable with the impedance Z _{H of the} load, it is necessary to reduce the inductance of the audio cable.

Known technical solution, US patent N2 US 5510578A, according to which the above described method is used to reduce the wave resistance - a prototype of reducing the inductance and wave impedance of a transmission line by parallel connection of twisted pairs of wires (two-wire transmission lines). The audio cable contains 18 twisted pairs of wires connected in parallel. The measured characteristic impedance of the audio cable is Z = 8 ohms. [five] The disadvantage of the known technical solution is the extremely large number of twisted pairs of wires in the cable design.

The audio cable according to US patent N ° US 539393 3A contains a two-wire transmission line in the form of two parallel strips (buses) located one after the other with a dielectric insulator between them. Characteristic impedance of an audio cable Z = 2 ··· 8 OM. The measured characteristic impedance Z = 4 ohms was obtained with 9.5 mm wide tires with b = 0.25 mm thickness and a polyester film gap with a = 0.076 mm thickness [6].

The disadvantage of this technical solution is the manifestation of the known proximity effect (a «b), which leads to an increase in the active resistance and inductance of the transmission line wires (see, for example, LA Bessonov Theoretical Foundations of Electrical Engineering ([3] pp. 700-702). The calculation showed an increase in inductance by a factor of 6 and an increase in resistance by a factor of 3. In addition, the busbars of the cable do not allow it to be arbitrarily bent without the risk of violating the stability of electrical parameters.

The audio cable disclosed by David Saltz in US Pat. No. JVT® US 8569627 contains a plurality of conductors, each of which consists of two or more metallic conductors arranged in a plane and touching each other, essentially forming parallel strips (tires). The conductors are run in parallel within at least two extruded insulators, which are installed back to back. The package of extruded insulators with conductors is twisted in the form of a spiral in the longitudinal direction and placed in a protective extruded sheath. [7] The technical solution has no disadvantages inherent in the above analogs: there is no proximity effect (a> b), the cable is compact, flexible and has stable electrical parameters.

This technical solution was taken as a prototype of a sound cable.

The disadvantage of the prototype is the relatively high characteristic impedance. Depending on the cable modification, Z> 23 ohm.

The proposed invention eliminates this disadvantage of the prototype by implementing in the audio cable the claimed method for reducing the inductance and wave impedance of the transmission line. This results in an audio cable with low inductance and reduced characteristic impedance to the level of the loudspeaker impedance. In addition, the matching of the audio cable to the load allows a multiple increase in the cable length in comparison with the accepted standard dimensions without compromising the fidelity of sound reproduction.

Disclosure of invention

A method for reducing the inductance and characteristic impedance of a transmission line, which consists in the fact that at least two two-wire transmission lines are connected in parallel.

Unlike the prototype, two-wire transmission lines are sequentially arranged one after another in such a way that the forward wire of each subsequent two-wire transmission line is placed behind the return wire of the previous two-wire transmission line, respectively, the return wire of each subsequent two-wire transmission line is placed behind the forward wire of the previous two-wire transmission line.

An audio cable that implements the method contains a plurality of conductors, each of which consists of two or more metal cores located in a plane and touching among themselves, the conductors are laid in parallel in the same plane inside at least two extruded insulators of N - pieces in each, where N> 1, extruded insulators with parallel rows of N conductors are installed close to each other, so that each conductor from the previous row of N conductors is aligned with the corresponding conductor from the next row of N conductors, a package of extruded insulators with conductors is twisted in the form of a spiral in the longitudinal direction and placed in a protective extruded sheath, one part of the plurality of conductors forms a straight wire of the audio cable, and the other part from multiple conductors form the return wire of the audio cable.

Unlike the prototype, in each row of N conductors, groups of S conductors belonging to the direct wire of the audio cable alternate with groups of S conductors belonging to the return wire of the audio cable, where S> 1, and behind each conductor belonging to the direct wire of the audio cable from the previous row N conductors there is a conductor belonging to the return wire of the audio cable from the next row of N conductors, respectively, behind each conductor belonging to the return wire of the audio cable from the previous row of N conductors, there is a conductor belonging to the direct wire of the audio cable from the next row of N conductors.

Brief Description of Drawings

FIG. 1 - oscillograms of a rectangular pulse at the load S and at the output of the pulse generator A in the case of matching the transmission line with the load Z _n = Z _H.

FIG. 2 - oscillograms of a rectangular pulse at the load S and at the output of the pulse generator A in the case of a mismatch between the transmission line and the load Z _L > Z _H. FIG. 3 is a schematic diagram of the parallel connection of 4 two-wire transmission lines.

FIG. 4 is a diagram of an arrangement of forward and reverse flat wires when 4 two-wire transmission lines are connected in parallel according to the inventive method.

FIG. 5 is a cross-sectional view of an audio cable with four rows of conductors in extruded insulators with two flat conductors in each row and six contacting cores in each

conductor.

FIG. 6 is a cross-sectional view of an audio cable with four rows of conductors in extruded insulators, with four conductors from two contacting conductors in each row.

FIG. 7 is a cross-sectional view of an audio cable with four rows of conductors in extruded insulators with two groups of two conductors in each row and two contacting conductors in each conductor.

FIG. 8 is a cross-sectional view of an audio cable with six rows of conductors in extruded insulators with six conductors from two contacting conductors in each row.

In FIG. 3 - FIG. 8, the conductors belonging to the direct wire of the audio cable are conventionally marked in white, and the conductors belonging to the return wire are in gray.

Detailed description of the invention

Both in the prior art method and in the method of the invention, two-wire transmission lines are connected in parallel. In the diagram of Fig. 3, this is

two-wire transmission lines 31, 32, 33, 34 with straight wires 35 and return wires 36. As a result, a transmission line with reduced characteristic impedance, where 37 is the forward wire of the transmission line, 38 is the return wire.

The method of the invention is illustrated by the diagram of Fig. 4, where

two-wire transmission lines 41, 42, 43, 44 in series

placed one after the other with a minimum allowable gap between the transmission lines. The forward wire 45 of the subsequent two-wire transmission line 42 is placed behind the return wire 46 of the previous

of the two-wire transmission line 41, respectively, the return wire 46 of the subsequent two-wire transmission line 42 is placed behind the forward wire 45 of the previous two-wire transmission line 41, etc.

Let us prove that in the invented method there is a decrease in inductance and wave impedance in comparison with the prototype, with the same number of two-wire transmission lines in parallel connection and equal impedances of the original (before connection) transmission lines. In each of the N two-wire transmission lines (hereinafter referred to as the lines), an electromotive force (emf) is induced due to self-induction in the line and mutual induction with the rest of the N-1 lines.

In the first line, in the order of the sequence of lines, the emf is equal to

in the second line emf is equal to

in the third line of emf is equal to (1)

in the fourth line emf is equal to

and so on, where L is the self-induction coefficient of the line, M _jk is the coefficient

_• „dii

mutual induction of the j-th line with the k-th line, -

is the rate of change of the current in the k-th line. In expressions (1) for the emf M _jk = M _{kj ·} . The index k in the designation of the current of this line can be omitted since the modulus of the reactance of the lines is two to three orders of magnitude less than the active resistance (\ X _L - X _c \ "R), therefore, the currents and the rate of their change in the lines can be taken equal to each other.

Taking into account the above, we rewrite formulas (1) for the case N = 4.

where the expressions in parentheses are the inductance L _j for the j - line. The mutual induction coefficient is related to the value of the flux linkage of the contours of a pair of lines and depends on the distance between the lines - the smaller the distance, the greater the mutual induction coefficient. Pairs of adjacent lines have the highest mutual induction coefficient, that is

Therefore, the inductance L _j lines in formulas (2):

L _± = (L - M ₂ i + M ₃₁ - M ₄₁ ) <L,

and we conclude about a decrease in inductance in the lines, which leads to a parallel connection to inductance

or in general for parallel connection of N lines

·

If in the prototype method the capacity C £

= N - С, where

- capacity of the parallel connection, C _to - capacity of the k-th line. Then, in the method of the invention, the capacitance C ^ increases many times, especially in the circuits of Fig. 3 and Fig. 4, where a flat forward and backward wire alternate one after the other (compare with a capacitor device). Characteristic impedance calculated by the formula Z =

decreases many times compared to the prototype, and

Calculation of the mutual induction coefficients M _jk does not make much practical sense. Therefore, we present the results of an experimental verification of the method. As a two-wire transmission line, a transmission line of a commercially available audio cable with a coplanar arrangement of strip wires in a fluoroplastic insulator was used (see Fig. 4). Audio cable parameters: width of strips W = 3mm, gap between strips S = 2mm, thickness 0.2mm, cable thickness in insulator 1mm .; linear inductance L = 0.75 μH / m, linear capacitance C = 20 pF / m, characteristic impedance Z = [W = 194 ohms.

In parallel connection of 4 lines according to the method of the invention we have. Measured, linear inductance

= 0.043 μH / m., Linear capacity C £ = 667 pF / m. Characteristic impedance Z =

= 8.03 ohm.

To achieve a characteristic impedance Z = 8 ohms in a parallel connection according to the prototype method, which is implemented in an audio cable according to US Pat. No. 5,510,578, 18 lines (twisted pairs of wires) were required, each with a characteristic impedance Z = 144 ohms. [five]. In parallel connection of 6 lines according to the method of the invention we have. Measured, linear inductance

= 0.029 μH / m., Linear capacitance C ^ = 1112 pF / m. Characteristic impedance Z = jL ^ / C ^ = 5.1 ohms.

The method for reducing the inductance and characteristic impedance of a transmission line is implemented in an audio cable, four embodiments of which are presented below.

The audio cable Fig. 5 contains 12 flat conductors, each of which consists of 8 copper conductors 51 with a diameter of 0.4 mm, located in the plane and in contact with each other. The conductors are laid in parallel in one plane inside 6 extruded insulators 52, 1.25 mm thick, two conductors 53 and 54 in each. The conductors 53 of the extruded insulators 52 belong to the forward wire (not shown) of the audio cable, and the conductors 54 belong to the return wire (not shown) of the audio cable. Extruded insulators 52 with two conductors are installed side-by-side such that conductor 54 from a subsequent extruded insulator 52 is located behind conductor 53 from a previous extruded insulator 52, and conductor 53 from a subsequent extruded insulator 52 is located behind conductor 54 from a previous extruded insulator 52 The material of the insulators 52 is polyethylene or other extrudable polymer. A package of extruded insulators 52 with conductors 53 and 54, measuring 7.5 X 7.5 mm, coiled in the longitudinal direction with a pitch of 30 mm (not shown) and placed in a protective extruded sheath 55. At the ends of the audio cable, all conductors 53 and all conductors 54 with insulators removed are electrically connected to each other, for example by soldering tin silver-plated solder, respectively forming the direct and return wires of the audio cable.

Thus, the four pairs of conductors 53 and 54 are, in fact, two-wire transmission lines connected in parallel with each other according to the method of the invention. The width of the flat conductors 53, 54 W - 3.2 mm and the distance between the two-wire lines of the audio cable Fig. 5 approximately coincide with the corresponding dimensions of the parallel connection of 6 lines in the above experiment according to the method of the invention. And the gap 5 = 0.5mm between conductors 53, 54 is 4 times smaller. It is known that a decrease in the spacing S in a coplanar strip line leads to a decrease in the characteristic impedance (characteristic impedance) of the Z line. In our case, the characteristic impedance Z of a two-wire line will decrease by 1.5 times (see the graph of the dependence of Z on the ratio 5 / (5 4- 2 W) in [8] page 262). Consequently, the characteristic impedance of the audio cable should also be reduced by 1.5 times compared to the parallel connection of 6 lines in the experiment according to the method of the invention. That is, when implementing the invention, one should expect Z <4 ohms.

The audio cable of Fig. 6 contains 16 conductors, each of which consists of 2 copper cores 61 located in a plane and in contact with each other. The conductors are laid in parallel in the same plane inside four extruded insulators 62, 4 conductors 63, 64, 65, 66 each. Conductors 63 and 65 belong to the forward wire of the audio cable and conductors 64 and 66 belong to the return wire of the audio cable. Extruded insulators 62 with parallel rows of four conductors 63, 64, 65, 66 are mounted side by side so that behind conductors 63 and 65 of the previous extruded insulator 62 conductors 64 and 66 from the subsequent extruded insulator 62 are located, and behind the conductors 64 and 66 from the previous extruded insulator 62 are conductors 63 and 65 from the subsequent extruded insulator 62.

A package of extruded insulators 62 with conductors 63, 64, 65, 66, measuring 5 x 5 mm, is coiled in the longitudinal direction with a pitch of 30 mm (not shown) and placed in a protective extruded sheath 67.

At the ends of the audio cable, all conductors 63, 65 and, respectively, all conductors 64, 66 with removed insulators are electrically connected to each other, for example, by soldering with tin-silver solder, respectively forming a forward and return wire of the audio cable.

In the structure of the audio cable in Fig. 6, we see two regions with parallel connection of two-wire transmission lines according to the method of the invention. One area 68 is highlighted with a dashed line. Parallel connection of two-wire transmission lines in these areas has a characteristic impedance Z ₀ = 18.6 ohms. As a result, for a sound cable we have linear inductance L = 0.068 μH / m, linear capacitance C = 832 pF / m and characteristic impedance Z = / L / C = 9 ohms.

The audio cable of Fig. 7 contains 16 conductors, each of which consists of 2 metal cores 71 located in the plane and in contact with each other. The conductors are laid in parallel in the same plane inside four extruded insulators 72 with 2 groups of conductors 73, 74 and 75, 76 in each. The group of conductors 73, 74 belongs to the forward wire of the audio cable, and the group of wires 75, 76 belongs to the return wire of the audio cable. Extruded insulators 72 with parallel rows of four conductors 73, 74, 75, 76 installed side-by-side one after another, so that behind the group of conductors 73, 74 from the previous extruded insulator 72 is a group of conductors 75, 76 from the subsequent extruded insulator 72, and behind the group of conductors 75, 76 from the previous extruded insulator 72 is a group of conductors 73, 74 from the subsequent extruded insulator 72.

A package of extruded insulators 72 with conductors 73, 74, 75, 76, measuring 5 x 5 mm, is twisted in the form of a spiral in the longitudinal direction with a pitch of 30 mm (not shown) and placed in a protective extruded sheath 77.

At the ends of the audio cable, all conductors 73, 74 and, accordingly, all conductors 75, 76 with removed insulators are electrically connected to each other, for example, by soldering with tin-silver solder, respectively forming a direct and return wire of the audio cable.

In this version of the audio cable, we have linear inductance L = 0.082 μH / m, linear capacitance C = 378 pF / m and characteristic impedance Z = yJL / C = 13 ohms.

The audio cable of Fig. 8 contains 36 conductors, each of which consists of 2 copper conductors 81 located in a plane and in contact with each other. The conductors are laid in parallel in the same plane inside six extruded insulators 82 with six conductors 83, 84, 85, 86, 87, 88 in each. Conductors 83, 85, 87 belong to the forward wire of the audio cable and conductors 84, 86, 88 belong to the return wire of the audio cable. Extruded insulators 82 with parallel rows of six conductors 83, 84, 85, 86, 87, 88 are installed side by side, so that behind conductors 83, 85, 87 from the previous extruded insulator 82 are conductors 88, 86, 84 of subsequent of the extruded insulator 82, and behind the conductors 84, 86, 88 from the previous extruded insulator 82 are the conductors 87, 85, 83 from the subsequent extruded insulator 82.

A package of extruded insulators 82 with conductors 83, 84, 85, 86, 87, 88, measuring 7.5 X 7.5 mm, twisted in the form of a spiral in the longitudinal direction with a pitch of 30 mm (not shown) and placed in a protective extruded sheath 89.

At the ends of the audio cable, all conductors 83, 85, 87 and, respectively, all conductors 84, 86, 88 with removed insulators are electrically connected to each other, for example, by soldering with tin-silver solder, respectively forming a forward and return wire of the audio cable.

In the structure of the audio cable in Fig. 8, three regions are seen vertically with parallel connection of two-wire transmission lines according to the method of the invention. One area 90 is highlighted with a dashed line. Since the regions 90 contain six two-wire transmission lines, against four in the regions 68 of the cable Fig. 6, the wave impedances Z ' _{0 of} parallel line connections in the regions 90 will be 1.5 times less than the wave impedances Z ₀ = 18.6 ohms in the regions 68 (see cable description Fig. 6), that is, Z ' ₀ * 12.4 ohm. Therefore, when carrying out the invention, the expected characteristic impedance of the audio cable is Z "4 ohms.

Technological note. Before soldering, in all versions of the audio cable, the conductors are protected with electrical insulating varnish along the entire bare length, except for the soldering point.

The described embodiments are examples of the present invention and do not limit the scope of the invention. Sources of information

1. Ed E. Reference manual for high-frequency circuitry.

Circuits, blocks, 50-ohm technology. Per. from German - M .: 1990. (prototype)

2. R. Feynman, R. Leighton, M. Sands Feynman Lectures on Physics, issue 6 Electrodynamics.

3. L. A. Bessonov Theoretical Foundations of Electrical Engineering (in three parts), ed. 5.

4. I.A. Aldoshina Article “Loudspeakers, part 7”, htlp: // vvw w .mo in Г in Go / articles Kui i speaker-- ⁷

5. US patent US5510578A.

6. US patent W US5393933A.

7. US patent N "US 8569627. (prototype)

8. E. F. Kuester Theory of waveguides and transmission lines (Course notes for ECEN 5114) https://b-ok.org/book/3429343/b767b9

Claims

Claim

1. A method of reducing the inductance and characteristic impedance of a transmission line, which consists in the fact that at least two two-wire transmission lines are connected in parallel, characterized in that the two-wire transmission lines are arranged in series one after the other in such a way that the straight wire of each subsequent two-wire line the transmissions are placed behind the return wire of the previous two-wire transmission line, respectively, the return wire of each subsequent two-wire transmission line is placed behind the forward wire of the previous two-wire transmission line.

2. A sound cable that implements the method according to claim 1 contains a plurality of conductors, each of which consists of two or more metal cores located in a plane and touching each other, the conductors are laid in parallel in the same plane inside at least two extruded insulators along N - pieces in each, where N> 1, extruded insulators with parallel rows of N conductors are installed close to each other, so that each conductor from the previous row of N conductors is aligned with the corresponding conductor from the next row of N conductors, a package of extruded insulators with conductors are twisted in the form of a spiral in the longitudinal direction and placed in a protective extruded sheath, one part of the plurality of conductors forms a direct wire of the audio cable, and the other part of the plurality of conductors forms the return wire of the audio cable, characterized in that in each row of N conductors groups alternate of S conductors belonging directly mu wire of an audio cable with groups of S conductors

18

SUBSTITUTE SHEET (RULE 26) belonging to the return wire of the audio cable, where S> 1, and behind each conductor belonging to the direct wire of the audio cable from the previous row of N conductors there is a conductor belonging to the return wire of the audio cable from the next row of N conductors, respectively, behind each conductor belonging to the return wire of the audio cable from the previous row N conductors is a conductor belonging to the direct wire of the audio cable from the next row of N conductors.

nineteen

SUBSTITUTE SHEET (RULE 26)