Hi-Fi audio lovers have noticed differences in the sound when changing the direction of interconnection cables long time ago – back in the seventies of the last century they began to draw arrows on audio cables that determine their input and output. The manufacturers claimed that the sound quality is better when the cable is run by the arrow, although no one could explain the reasons for this behavior of the cables without logical contradictions. Attempts to explain this phenomenon at the level of physics were also not successful, measuring devices did not register any significant changes in the electrical signal when the wire was reversed, however, at the level of subjective impressions, these phenomena was confidently confirmed.
Subjective impressions, like a voltmeter and an oscilloscope, is a measuring instrument in audio engineering. This means that under certain methodological conditions, auditory measurements (subjective measurements) are recognized as substantial. They are widely used in psychophysics and in audio expertise. In contrast to the so-called objective measurements, subjective measurements contain a large statistical error, so it is necessary to evaluate the reliability of the results obtained. Subjective measurements can be considered reliable if one expert or several experts in a blind test have estimates repeated in, say, 80-90% of cases. The reliability depends on the experts’ ears, the musicality of the material used, the clarity of the evaluation criteria, and revealing of the system [2].
The study of the directionality of wires and audio elements in the signal chain of audio systems began in the same seventies. At the moment (2005), the known results are quite contradictory: on the one hand, it was found that the directions of the wires in the circuit section between the DAC and the input tube grid are closed into contour. Moreover, the cold (ground) wire is directed towards the DAC “from effect to cause”, and the hot (signal) wire is directed to the grid of the input lamp “from cause to effect” [3]. The same rule was established in the section “tonearm cartridge – input tube grid of the RIAA corrector” [4]. On the other hand, there is an opinion that both the signal and ground wires should be oriented “from cause to effect” [5]. At the same time, few researchers took into account that the correct direction of the wires and all other elements of audio amplifiers are equally important in signal and in DC/AC mains circuits. The article provides recommendations on how to choose right component direction for each circuit of the audio system.
Terms and definitions
The nature of the wire sound connected in the forward and reverse directions differs in its Coloration and Clarity. There are other more subtle differences, but we will not touch on them here.
Coloration is “…the accentuation (or darkening) of certain frequency regions of the sound range, which is marked by our perception” [7] . This emphasis can be both subjectively harmonious, and vice versa. Each component of the audio system has its own individual, inherent only to it, coloration. The overall coloration of the system is a kind of “chorus”, consisting of individual colors of each component and each piece of wire. In a revealing system, the voice of each component is heard. Therefore, to achieve the natural sound, components and wires are selected only with a natural, harmonious, mutually complementary colorations. This is how the harmonization of the sound of the system is achieved [8].
Clarity – wherever the opposite is not indicated, Musical Clarity is meant. It is a subjective characteristic of the sound that closely intersects with the concept of sound-carrying that is a criterion from the vocabulary of violin makers. Clarity is a key indicator of the sound quality of audio equipment [9]. Clarity is responsible for the intelligibility and amount of details of the sound, determines the ability of the system to convey intonation and distinctive features of the performer. The loss of clarity increases with the addition of each new component, wire, or connection in the system.
The correct direction of the wire is the direction that provides the highest Musical Clarity of sound. Subjectively, the increase in Clarity is accompanied by the enlightenment and enrichment of the HF, the sound as a whole becomes less veiled, more natural and plastic[10]. It happens that sound of a wrong directed wire is more balanced tonally in systems with no or insufficient clarity and therefore it is quite easy to prefer the wrong direction. However such wire inclusion is not recommended, since the loss of clarity is not compensated, while the tonal imbalance can be eliminated by harmonizing the system with selective elements and wires connected in the right direction.
Experimental Audio System
The survey was carried out on a tube, single-ended amplifier (Fig. 1), its features correspond to the principle of the shortest path of the signal [11]. The shortest signal path guarantees the highest possible revealing of the audio reproducing system at the initial stage of operation, when the conductors are mostly randomly oriented.
Method for determining the direction of wires and elements
Stage A – determining the correct direction of the conductors and marking them: A long piece of solid core wire was connected between J10 and J13 (see fig 1) first in one direction and then in the other. After determining the correct direction, the beginning of the wire has been marked with paint.
Stage B – each wire in the amplifier wiring in turn, starting from the signal chain, was replaced with segments of the wire marked at stage A. Each new marked piece of wire was tested at its new place in both directions and position with the best sound of the conductor was selected, only then the wire was finally soldered. Upon completion, the direction arrows were applied to the diagram Fig 1 according to the marks on the replaced wires.
The experimental system, even with the initially arbitrary directions of the conductors and elements, had enough revealing to reliably determine the correct directions of the elements and wires in the signal part of the amplifier. When working in step B, the sound clarity of the amplifier had been increasing with each conductor and element turned in the correct direction. At the end of stage B, the sensitivity to the direction of the components became so high that it allowed us to determine the correct direction of the tubes socket pins, the filaments of the tubes, metal parts of RCA connectors, power plugs and sockets, resistors (their carbon coating) and capacitors. As a result of the analysis of the acquired direction schematic, the following rule were formulated:
For the sake of order, all the contours in the audio system can be contingently divided into two groups:
–The first group of contours is the contours through which a constant current flows or which have sections with a constant component of the electric current. In such contours, the direction of the conductors and components coincides with the direction of movement of the electrons in the sections of the circuit with a constant current component. This group is divided into general circuits, which contain a mutual branch No.1 (MB1): “TR3-W2, VL3, TR3-W3 and the conductors connecting this circuit (Fig.1) and local contours.
The amplifier circuits in Figure 1 contains ten general contours and one local contour. The general contours contain, in addition to the wires and the tube sockets contacts, omitted for simplicity, the following components:
- MB1, С5.
- MB1, С4, L1.
- MB1, VL2 cathode-anode, TR2-W1, L1.
- MB1, BAT2, R3, VL2 grid-anode, TR2-W1 , L1.
- MB1, VL1 cathode-anode, C3, VL2 grid-anode, TR2-W1 , L1.
- MB1, VL1 cathode-anode, R2, L1.
- MB1, BAT1, R1, сетка-анод VL1, C3, VL2 grid-anode, TR2-W1, L1.
- MB1, BAT1, R1, сетка-анод VL1, R2, L1.
- MB1, J14, Cable, J12, DAC, J11, CABLE, J13, C2, VL1 grid-anode, C3, VL2 grid-anode, TR2-W1 , L1.
- MB1, J14, Cable, J12, DAC, J11, CABLE, J13, C2, VL1 grid-anode, R2, L1.
One local contour:
- TR3-W2, VL3 filament
The second group of contours are contours that do not contain sections with a constant current component. In them, the direction is set by the mains voltage generator. The schematic contains seven contours belonging to the second group:
-
Contours 1 and 2 contain a mutual branch No. 2 “TR3-W4”.
- TR3-W4, VL1 filament
- TR3-W4, VL2 filament
- TR2-W2, SP1
- TR2-W2, C4, SP2
- MB4, TR1-W1
- MB4, TR1-W1
- MB4, Field coil speaker power supply.
Contours 1 and 2 contain a mutual branch No. 2 “TR2-W2”.
Contours 5, 6 and 7 contain a mutual branch No. 4 (MB4), which starts from the mains socket and passes through the entire wiring of the house, then through the generator winding or the step-down winding of the substation and returns to the mains socket. If you live in the city in apartment house, this branch become the weakest point of a audio system, which can only be improved by using an independent, analog power mains generator.
When wiring the amplifier, it is important to follow the sequence of connections of the contour groups with the corresponding mutual branches shown in the schematic (ie the tube cathode circuit should always be connected closer to the power transformer than the grid circuit). A violation of the sequence of mounting contours reduces the clarity of the system sound. If there are extraneous electrical devices in the room that are powered from the same phase as the audio system, then they must be connected to contour No. 8 (closer to the 220 V generator than field coil power supply) and oriented to the contour with MB4.
The general contours in the power supply of the DAC follow the above rules also. Using the rules, you can determine the contours and their directions of any amplifier stage. These rules were checked and confirmed by A. Likhnitsky during the wiring of the push-pull amplifier.
Distinctive features of the amplifier
Components – The system uses wires and components from Telefunken and Siemens receivers from the 30s-40s.
Signal capacitors – are homemade: copper foil – oiled paper. The terminals of the capacitors are connected to the foil without soldering – the roll is just tightly twisted and pulled together with electrical tape. When assembling, the directions of the foil and terminal wire are taken into account.
Rectifier – half-wave [12] – a standard full-wave rectifier sounds less clear.
Resistors – the terminal wires are connected directly to the graphite coating, taking into account the directions of both the wires and the graphite coating.
Tube socket pins, audio and mains connectors – Like all other conductors, all the other metal parts are directional. The sockets are assembled using pins with the necessary directions according to the outline scheme. RSA connectors, both “mom” and ” dad ” on the interconnection cable, are made from selected parts with necessary directions.
Signal source – to achieve the shortest possible audio signal path, the signal is taken directly from the output pins of the DAC, all filters are omitted.
Speaker – “Noema” – 75GDSH33-16, the voice coil has been rewound with Telefunken 1930s wire and was connected directly to the output contacts without using stranded wire.
Music material – CD discs with remastering of jazz and classical records from the 1940s-1960s.
Installation – Wherever possible, instead of soldering, wires are just tightly twisted together. The signal capacitors and signal wires do not touch the steel chassis. Only solid-core wires are used, as in stranded wires, the veins (small gauge solid core wires) are often go different ways. The sound of stranded wires is always less focused than that of a solid-core ones.
Footnotes:
[1] – A. M. Likhnitsky Reflections on the sound coloration, AM No. 1(48), 2003 pp. 160-163.
[2] – F.E.Toole. Listening test – Turning Option into Fakt. – JAES, V. 30, No. 6, 1982, p. 431-445.
[3] – Established by Oleg Havin (stated earlier on the forum www.aml.nm.ru)
[4] – Established by Anatoly Likhnitsky (stated earlier on the forum www.aml.nm.ru)
[5] – Established by Evgeny Komissarov (stated earlier on the forum www.aml.nm.ru)
[6] – A.M. Likhnitsky “Sound quality – a new approach to testing audio equipment”. “Peak” St. Petersburg 1998 p. 13-20
[7] A. M. Likhnitsky “How to talk about what we hear” AM №5(10), 1996 p. 45.
[8] A. M. Likhnitsky “Testing the audio cables” AM №2(3) 1995, p. 43.
[9] A. M. Likhnitsky “Testing the audio cables” AM №2(3) 1995, p. 44.
[10] – In complex transistor amps, the HF concentration is the only reference point. The sound begins to “come to life” only after reaching a certain threshold, which is quite difficult to achieve on transistor technology with multi-way speakers.
[11] – “Revived recording” Interview with A.M. Likhnitsky AM, No. 1/1994
[12] – The preferred sound of a half-wave rectifier was first noted by Sergey Shabad.
[13] – Established by Oleg Havin on the forum www.aml.nm.ru
Article review – 10-07-2005, by AML+
Most of the information we get from the world around us: newspapers, television, the Internet (including our forum) has zero value. Only in very rare cases do we witness an information breakthrough, that is, the appearance of really valuable, otherwise new and important information for achieving certain goals. Anton’s article on our website is such a breakthrough.