jer0en
2007-04-29 23:46:29 UTC
I have made some drawings so now I would like to show them to you. If you ever intend to make modifications to your record player set, it may be useful to have a copy of this document, somewhere. Here's the first.
RIAA.BMP
PHONO AMPLIFICATION
This is the logical schematic of a stereo phono preamplifier that applies "RIAA correction", a correction that is to be applied to all recordings on vinyl, because they are all recorded with the opposite algorithm, but that is not included in every phono amplifier, possibly for reasons unknown.
Amplifiers that have a phono input already have a phono amplifier built in (that is normally RIAA corrected) and for this reason are often referred to as integrated amplifiers. For amplifiers without a phono input separate phono amplifiers are available, some of which come as small boxes that may be run on a 9V battery, with one of which the above schematic was actually shipped.
The purpose of a phono amplifier is to bring the low voltage MM / MC phono signal up to "line" level, i.e. the level that is used by all input connectors of an integrated amplfier besides phono. So the output of a separate phono amplifier may be used as input for all analogue input connectors of any amplifier, except phono. This also means that if you have separate pre and end amplifiers, the preamplifier will either be a very expensive phono amplifier, i.e. if a phono input is present, or a very expensive switch box, in which there is no amplification activity whatsoever.
To actually get the phono signal up to line level, the above design requires a minimum phono signal level of around 3 mV, which means that this preamplifier will only work with either MM (MD) cartridges, that usually have an output of around 5 mV, or with "high out" MC cartridges. The higher the phono input level, the better its signal / noise ratio and the higher the line output level.
The phono signal, like all AV signals, is physically just a form of AC that is to be, in this case, analoguely interpreted as carrying audio information, and to be eventually reproduced as such. With the exception of XLR systems, analogue audio signals are carried via a cinch (RCA) plug over a cinch interlink cable that has a positive core and a negative mass, that is additionally used for shielding the core.
The phono signal enters the phono amplifier by connecting the positive core of the cinch cable to the designated points of input, either by using a removable cinch plug or, for best results, by making a soldered connection. The negative complement of the phono signal, the phono mass, that passes through the cinch cable's shielding, is ignored, at least as a signal, but it must be connected to make a circuit.
The phono signal, which is a two-channel or stereo signal, is generated in the phono cartridge by two inductive coils, one for each channel, that each convert the kinetic energy of the vibrating stylus into a corresponding AC signal. Since each coil has two wire ends, the phono cartridge has four terminals, that carry the two AC signals, left and right, via four tone arm wires to two cinch plugs at the back of the turntable. So basicly the coils directly connect to the phono amplifier.
USED COMPONENTS
The above design only uses the three main types of electrical components, i.e. capacitors, resistors and transistors.
CAPACITORS are made of two separate plates, usually sheets of foil, that can each hold an amount of charge. But instead of carrying the charge itself, they only carry its electrical field, which induces a charge shift in the opposite plate. This is sufficient to carry an AC signal, within certain limits depending on the quality of the capacitor, but never so sufficient it could carry the continuous flow of DC.
However, with a big enough charge and small enough distance between the plates, charge will pass on by way of discharge, the phenomenon of lightning, which in audio is commonly known as clipping. Clipping allows DC current to reach places that can only handle the huge peak, but in comparison minute continuous power requirements of audio AC signals (at least at line level, and if relatively undistorted at the speaker level as well), like the speaker coils, causing them to burn.
Greater charges in the plates are caused by higher voltages between them, and the main secondary specification of a capacitor is therefore the maximum voltage it allows. A higher voltage allowance necessarily means a bigger size. Since capacitance is calculated as C=A/d, where A is the area of the plates and d the distance between them, and A is the main factor deciding the level of distortion, capacitors with a large value for both A and d are better, so a bigger size necessarily means better performance.
Electrolythic capacitors can actually hold so much charge that they will act as very fast rechargeable batteries and therefore as additional DC power supplies. In amplifiers capacitors act as giant eardrums, that are used to separate different amplification sections that run at different voltages. In a record player set the phono amplifier is a separate section, the power or end amplifier is, and may itself be divided into multiple sections, and of course at the input end the phono circuit is, and at the output end the speaker circuit, which both run at zero DC voltage.
Capacitors are measured in Farad (= 1 Coulomb / Volt), which is rather a large measure in electronics, so values range from picoFarads up to microFarads. NanoFarads are seldom used as a unit; values typically range from 1 to 100,000 pF, and from 0.1 to 1,000,000 µF. Normally, only electrolythic capacitors will have values above 10 µF, and they do not have values below 1 µF. Because by the type of capacitor it is usually sufficiently clear which range of values it is in, the unit, pF or µF, is often omitted. Some form of coding may be used, that is a digital variety of the colour band code as used on resistors, i.e. "10" followed by a third digit specifying the number of zeros to add. In that case "103" is not 10 to the 3rd power, but rather the 4th, so 10,000.
RESISTORS are used to lower both current and voltage at a particular point in a circuit. Since V=I.R (voltage=current.resistance), V and I are quite evenly reduced when a current passes a resistor, V after the resistor and I before and after. For AC signals resistors can be largely interpreted as adapting just the current, because that current is usually too low to significantly change the voltage.
Resistors of many different materials are made, but they all actually carry charge, i.e.both AC and DC current, and as the immedeate result they heat up. This heat must be dissipated into the surrounding air, and therefore the ability of a resistor to dissipate its heat, i.e. its ability to keep cool, is its main secondary specification, measured in Watts.
Since heat dissipation is proportional to the area of the resistor surface, more dissipation ability necessarily means a bigger size. Inside the resistor, the added space is used to increase the diameter and the length of the resisting material, typically wound in a spool of thread, to allow for more current. Because the diameter, i.e. more mass of conductive material per length, is, in resistors as well as in other signal paths, a more important factor to the level of distortion than the length, a bigger size necessarily means better performance.
In amplifiers resistors are used to direct the flow of power supply and of AC signals within an amplification section.
Resistor values may vary from 0.1 Ohm (W) up to 99 megaOhms. On each resistor a three color band code is printed indicating its value. black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, purple=7, grey=8 and white=9. The first two bands form a two digit base value, while the third band indicates the following number of zeros. The third band may also be gold or silver. A third black band would indicate a value between 10 and 99 W, a third gold band a value between 1 and 9.9 W (x0.1) and a third silver band a value between 0.1 and 0.99 W (x0.01). A fourth band usually indicates the value's "tolerance", gold for a 5% maximum difference between printed and actual value, silver for a 10% maximum difference. Resistors come in series of standardised values, the E96, E24 and E12 series. Generally only E12 values are used. Within E12, the two digit base value can only be one of the following: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82. These values come in any number of zeros.
TRANSISTORS may be described as analoguely programmable resistors, that have three leads, an input, an output and a data input. A "program current" is set on the data input, as a function of which current will be allowed to pass from the input to the output. What kind of function depends on the type of transistor. Usually it will be a linear function, simply multiplying the program current. If that program current would be an AC signal, its amplitude would be multiplied, i.e. the signal would be amplified.
There are two types of transistors. On both types the data input is called the basis. On PNP transistors the input (positive) is called the emitter and the output (negative) the collector. On NPN transistors the collector is positive and the emitter negative. Current can not flow from output to input.
Transistors have a bunch of specifications, the type (PNP / NPN), the material (germanium / silicon), the order of the leads, the package (the standardised metal or plastic mould surroundig the transistor, and the cooler plate), the heat dissipation in Watts (P), the Hfe value (the multiplying factor), the Ft value (maximum or terminating frequency) and last but not least the "use", because a transistor may have all the right specs, but if it was made as an RF switch it cannot be used as an audio amplifier.
Because transistors are very vulnerable, the voltage allowances between the individual leads (Vbe, Vcb and Vce), as well as the maximum current it can handle (Imax) are primary specifications as well. If these values are only slightly exceeded, the transistor is likely to burn instantly. The same applies to ICs and chips, which are even more particular, specifically those at low voltages.
This already shows that you cannot just ask for a type of transistor, you must ask for a particular one. Therefore every transistor that is manufactured is given a unique number. Transistors are produced in three world regions, North and South America (numbers starting with 2N), East Asia (numbers starting with 2S, usually omitted) and Europe (numbers starting with a letter). Transistor numbers are listed in transistor guides, that list the specifications of tens of thousands of transistors, starting from the 1960s when they were first produced. Today these specifications can usually be found on the internet.
THE SCHEMATIC
The above schematic is horizontally symmetrical, showing identical sections for each of its two channels.
For each channel, a pair of identical NPN medium current audio transistors, with an amplification ratio (HFE) of 250 minimal, are used to consecutively amplify the incoming phono signal to line level.
Power is supplied by a 9V battery. A single capacitor of 100 µF is used as an additional power supply for both channels. Two capacitors of 47 µF on the emitters of the second transistors are used as local power supplies.
The two NPN transistors are supplied with DC power of the positive kind via their collectors, past resistors of 120 kW and 12 kW resp. After signal amplification, current is released to the negative side via their emitters, past resistors of 470 W and 2.2 kW resp.
The output signal of each transistor is received from their collectors.
The phono signal first passes, or rather, does not pass a 56 kW overload safety resistor onto signal mass and negative power. Next it does pass a 1 kW mitigator resistor.
Subsequently it passes a 1 µF input capacitor. The input capacitor separates the phono cartridge from the phono amplifier electrically, allowing the latter to run at a higher voltage, without DC flowing back into and burning the cartridge, while connecting them logically, allowing AC to be accepted from the cartridge.
Thus the AC phono signal, having the same amplitude but at a higher voltage, reaches the basis of the first transistor. The purpose of which is to increase the amplitude, not the voltage level at which it occurs.
Inside an amplifier (section), that will always run at a particular (non-zero) voltage, AC signals can only exist as fluctuations of that voltage level, i.e. of an already existing general flow of current that, in this case (NPN + NPN), will always be greater than the greatest opposite fluctuation of the AC signal, so the flow of current will vary in measure, but never actually in direction.
As a linear function of the AC signal on the basis, current now passes through the first transistor's collector towards the emitter, at a rate, i.e. with an amplitude that is increased by a (HFE) factor of 250 or more.
Part of the first transistor's collector current is coming from the basis of the second transistor, the exact amount or ratio of which is determined by the value of the collector's power resistor, which is 120 kW. Note that this will cause a negative copy of the original signal to arrive at the basis of the second transistor.
In the second transistor the amplification process is repeated, only now with a higher input signal on the basis, which is then amplified by a factor of 250 once more.
Finally the relatively large power requirements of the second collector will resonate on a 10 µF output capacitor, the exact amount or ratio of which is determinded by the collector's power resistor, which is 12 kW. Note that this will cause the negative copy of the signal to become a positive again. Not that it matters, it is just a phase shift.
To prevent oscillation, a small 50 pF capacitor is put between the collectors of the two transistors, and a 470 kW resistor between the basis of the first transistor and the emitter of the second.
The RIAA correction section consists of two resistor / capacitor pairs, in the top centre of each channel section, one pair of 15000 pF and 220 kW, and a second of 4700 pF and 18 kW, connecting the emitter of the first transistor with the collector of the second.
AND BEYOND
This does not, of course, fully explain the mechanics of the phono amplifier, and new and useful questions would arise in nearly any creative mind to contemplate them, also considering that, at the speed of light, all constants will become one (1), all quantities will become one (one) and all forces identical phenomena. But it does begin to describe it.
Note however that the flow of current is a completely virtual concept inasmuch it will always go from positive to negative, while any electron in the universe will only go from negative to positive. Which puts constraints on the applications of the general electro-dynamical model in that it can only be used to explain aspects of electro-dynamical phenomena that are actually reciprocal.
Whereas on the level of perception of common electrical circuits the difference between the quantities V and I often seem anything but perfectly distinct, they do in fact project on distinct phenomena occurring between force fields on the subatomic level.
Considering force field interaction, a few things can be established. In the first place, it takes two force fields to have an interaction, without which the existence of the universe would be completely arbitrary. So, by definition, force field interaction is a mass, or at least a multiple field phenomenon, and any scientific model staying with the singular aspects of force fields would be inherently useless. A useful model would require at least two (2) fields.
Secondly, any force field in the universe will only interact with fields of its own species. To all other species it is completely neutral, to the extent that its existence cannot be established, and might as well be in another dimension, or another level of the universe, and probably is. Note that these truths have a limited physical application, and by no means could apply right down to the religious level, or even to the conceivability of such an event, where many different types of interaction would be involved.
However all force fields do share in common that, in 3-dimensional space, they expand with the speed of light, and the strength of the field diminishes from the centre 2-dimensionally rather than 3-dimensionally. Due to the latency of the speed of light, inside moving force fields Doppler-like effects are to occur to the field strength, which f.i. would explain that a gravity field moving at light speed would be infinitely heavy at the front, but completely weightless at the rear. The same would, of course, apply to other fields.
Keeping in mind that their centres are empty, and that the object of any force would be the force field as a whole, in all its infinity, such centres could be experimentally extrapolised, in that the distance between them would be indicative of the level in which the spheres of influence of the respective force fields would be sharing the same space, and virtual plains of intersection be plotted, of an infinite size, the centre point of which would have a particular level of reciprocal seizing effectivity, with a differentiated maximum density of field lines, showing the level of attraction or rejection between them, at a particular point in time.
Which would allow us to delete the current subject / object model as used in force field physics, and pass on to a more useful subject / subject model, without any implicit notions of hierarchy inherent in the subject / object model, whichever way around.
At the point of intersection of electrical force fields, i.e. at a particular point in time, the field line density is corresponding with the voltage as measured in electrical circuits. The number of force fields interacting, dramatically increasing the amount of kinetic energy in that part of the universe, is corresponding with the current.
Voltage and current may be at least partly dynamical phenomena in free space, in disconnectable electrical circuits they are typically kept static, as without current the voltage will not change either.
Due to the materials used in common eletrical circuits, that feature an abundance in free electrons, even when the circuit is connected we are immedeatly faced with the mechanics of congestion. Instead of applying to the behaviour of individual particles, V and I are now properties of a flow of streaming particles that act as one body, applying to locations in the circuit.
Typically in a 1 square mm cable and at 1 ampère an individual electron will move at a speed of 1 mm / second. This doesn't seem to be harmful to anyone. But that speed is just a fractional part of a chain reaction that expands with the spead of light, which acting as a whole, and there being 1 coulomb or free electrons in every cubic mm of conductive material, could definitely kill us.
SHIELDING
Before and during amplification both phono and line level signals are to be properly shielded to fight signal distortion.
Whether cinch or XLR is used to connect audio decks, signal protection through shielding is achieved by creating a chain of interconnected cages of Faraday, that eventually connect to mains null (cinch) or to mains ground (XLR), because a cage of Faraday must be connected to ground to actually become one. The chassis of the decks are used as cages, which are interconnected by the shielding of cables that act as cages as well. To be able to connect to mains null in cinch systems, shielding and chassis are connected to and identical with the signal mass and negative power.
Inside an amplifier, the signal mass directly connects to the negative pole of the power supply, and in many cinch amplifiers even directly to the chassis of the deck. The latter actually makes the chassis part of the low voltage circuit. This is normally harmless, since it will be at the negative end of the circuit and any current in it will directly drain away to mains null, resulting in zero voltage. It may even improve performance, but some reverence should be observed when connecting such decks to an earthed outlet, unless you like unpredictable results, since they were clearly not designed for this. Generally it will even work.
On XLR systems the positive and the negative complement of the audio signal are carried over two separate shielded cores, and the XLR connector has three poles. The negative signal complement (mass) connects to negative power only, and the shielding connects to the chassis only. They must be kept stricktly separated through all decks connected, and the decks should draw power from earthed outlets, since their chassis are to connect to the mains ground wire for the shielding to become effective.
The above schematic is cinch based but could theoretically be used for XLR as well. In that case the connection of signal mass and negative power to chassis (bottom right in the schematic) should not be made. Instead, the chassis that would hold the phono amplifier would have to be electrically isolated from it and be (somehow) connected to the XLR cables' shielding, both in and out.
The cinch and XLR story is pretty straightforward and among other things explains why the systems should not be mixed, that is, with the kind exception of the cinch connected MM / MC turntable. Because of its extremely low voltage, the MM / MC phono signal is extremely succeptible to electro-magnetic interference, at least before it is brought up to line level by the phono amplifier.
For a cinch connected turntable this means that, BEFORE the phono signal is brought up to line level, the negative complement of the phono signal created by the cartridge (phono mass) cannot be used to additionally drain away the interference caught on by the chassis of the turntable, by connecting the two as is usual in other cinch oriented decks. Due to its low voltage, this would cause an intolerable signal / noise ratio on the positive complement of the phono signal. Don't ask me why, cause I dunnoh.
However, for the cinch turntable chassis, specifically the tone arm and the shielding of the tone arm wires outside of it, to become part of the cage of Faraday system and hence effective as shielding, it must be connected to the cage system by another means than the phono mass. Therefore every cinch turntable has a separate ground connector, that connects to an identical provision on the phono or integrated amplifier.
Note that this makes for a peculiar protection sequence in cinch turntables. On the turntable, the tone arm wires are shielded by the tone arm, and subsequently in the turntable by some other form of shielding, whether it be a wick, metal foil or the deck itself. But outside of the turntable, in the cinch cable, the phono signal is shielded by the phono mass again, which is eventually to connect to the turntable chassis, but not beforel the phono signal has been preamplified, or at least has reached the preamplifier.
In fact, the cinch turntable is an XLR component in an otherwise cinch based audio system. And it would be optimal, and quite feasable, to actually use some form of XLR cabling to connect it to the phono amplifier's input, while using cinch cabling for the phono amplifier's output, in case you were to build one yourself. As long as phono mass and shielding / chassis are not to connect before the phono amplifier, and ideally even at its output end. Note that as a whole the system would remain cinch based, and that none of the connected decks is to connect to an earthed outlet.
Typically you would isolate the XLR terminals from the phono amplifier's chassis at the input end, and make shure to connect the cinch terminals with the chassis at the output end. You would then have to make XLR terminals on your turntable. Instead of two, you would now have four shielded connections, two phono signals, two phono masses and a shared shielding that is connected to the tone arm, the shielding of the tone arm wires inside the turntable and the rest of the turntable chassis. Of course, if you want professional results, these would all have to be soldered connections, at least for the XLR connections carrying the phono signal.
To top it off, phono cartridges have specifications as to which terminals are their signals and which their signal masses. Though one is a negative copy of the other, it is not in fact arbitrary, since both coils are to one end connected to the cartridge chassis in order to drain away, any outside magnetic interference. This is why the catridge chassis should be isolated from the head-shell, to prevent phono mass and turntable chassis from being connected prematurely. If you are in doubt, switch the head-shell wires on the cartridge to determine which orientation produces best results. There should be an audible difference.
They used to have crystal cartridges that directly produced line level output. Next picture.
RIAA2D.BMP
RIAA.BMP
PHONO AMPLIFICATION
This is the logical schematic of a stereo phono preamplifier that applies "RIAA correction", a correction that is to be applied to all recordings on vinyl, because they are all recorded with the opposite algorithm, but that is not included in every phono amplifier, possibly for reasons unknown.
Amplifiers that have a phono input already have a phono amplifier built in (that is normally RIAA corrected) and for this reason are often referred to as integrated amplifiers. For amplifiers without a phono input separate phono amplifiers are available, some of which come as small boxes that may be run on a 9V battery, with one of which the above schematic was actually shipped.
The purpose of a phono amplifier is to bring the low voltage MM / MC phono signal up to "line" level, i.e. the level that is used by all input connectors of an integrated amplfier besides phono. So the output of a separate phono amplifier may be used as input for all analogue input connectors of any amplifier, except phono. This also means that if you have separate pre and end amplifiers, the preamplifier will either be a very expensive phono amplifier, i.e. if a phono input is present, or a very expensive switch box, in which there is no amplification activity whatsoever.
To actually get the phono signal up to line level, the above design requires a minimum phono signal level of around 3 mV, which means that this preamplifier will only work with either MM (MD) cartridges, that usually have an output of around 5 mV, or with "high out" MC cartridges. The higher the phono input level, the better its signal / noise ratio and the higher the line output level.
The phono signal, like all AV signals, is physically just a form of AC that is to be, in this case, analoguely interpreted as carrying audio information, and to be eventually reproduced as such. With the exception of XLR systems, analogue audio signals are carried via a cinch (RCA) plug over a cinch interlink cable that has a positive core and a negative mass, that is additionally used for shielding the core.
The phono signal enters the phono amplifier by connecting the positive core of the cinch cable to the designated points of input, either by using a removable cinch plug or, for best results, by making a soldered connection. The negative complement of the phono signal, the phono mass, that passes through the cinch cable's shielding, is ignored, at least as a signal, but it must be connected to make a circuit.
The phono signal, which is a two-channel or stereo signal, is generated in the phono cartridge by two inductive coils, one for each channel, that each convert the kinetic energy of the vibrating stylus into a corresponding AC signal. Since each coil has two wire ends, the phono cartridge has four terminals, that carry the two AC signals, left and right, via four tone arm wires to two cinch plugs at the back of the turntable. So basicly the coils directly connect to the phono amplifier.
USED COMPONENTS
The above design only uses the three main types of electrical components, i.e. capacitors, resistors and transistors.
CAPACITORS are made of two separate plates, usually sheets of foil, that can each hold an amount of charge. But instead of carrying the charge itself, they only carry its electrical field, which induces a charge shift in the opposite plate. This is sufficient to carry an AC signal, within certain limits depending on the quality of the capacitor, but never so sufficient it could carry the continuous flow of DC.
However, with a big enough charge and small enough distance between the plates, charge will pass on by way of discharge, the phenomenon of lightning, which in audio is commonly known as clipping. Clipping allows DC current to reach places that can only handle the huge peak, but in comparison minute continuous power requirements of audio AC signals (at least at line level, and if relatively undistorted at the speaker level as well), like the speaker coils, causing them to burn.
Greater charges in the plates are caused by higher voltages between them, and the main secondary specification of a capacitor is therefore the maximum voltage it allows. A higher voltage allowance necessarily means a bigger size. Since capacitance is calculated as C=A/d, where A is the area of the plates and d the distance between them, and A is the main factor deciding the level of distortion, capacitors with a large value for both A and d are better, so a bigger size necessarily means better performance.
Electrolythic capacitors can actually hold so much charge that they will act as very fast rechargeable batteries and therefore as additional DC power supplies. In amplifiers capacitors act as giant eardrums, that are used to separate different amplification sections that run at different voltages. In a record player set the phono amplifier is a separate section, the power or end amplifier is, and may itself be divided into multiple sections, and of course at the input end the phono circuit is, and at the output end the speaker circuit, which both run at zero DC voltage.
Capacitors are measured in Farad (= 1 Coulomb / Volt), which is rather a large measure in electronics, so values range from picoFarads up to microFarads. NanoFarads are seldom used as a unit; values typically range from 1 to 100,000 pF, and from 0.1 to 1,000,000 µF. Normally, only electrolythic capacitors will have values above 10 µF, and they do not have values below 1 µF. Because by the type of capacitor it is usually sufficiently clear which range of values it is in, the unit, pF or µF, is often omitted. Some form of coding may be used, that is a digital variety of the colour band code as used on resistors, i.e. "10" followed by a third digit specifying the number of zeros to add. In that case "103" is not 10 to the 3rd power, but rather the 4th, so 10,000.
RESISTORS are used to lower both current and voltage at a particular point in a circuit. Since V=I.R (voltage=current.resistance), V and I are quite evenly reduced when a current passes a resistor, V after the resistor and I before and after. For AC signals resistors can be largely interpreted as adapting just the current, because that current is usually too low to significantly change the voltage.
Resistors of many different materials are made, but they all actually carry charge, i.e.both AC and DC current, and as the immedeate result they heat up. This heat must be dissipated into the surrounding air, and therefore the ability of a resistor to dissipate its heat, i.e. its ability to keep cool, is its main secondary specification, measured in Watts.
Since heat dissipation is proportional to the area of the resistor surface, more dissipation ability necessarily means a bigger size. Inside the resistor, the added space is used to increase the diameter and the length of the resisting material, typically wound in a spool of thread, to allow for more current. Because the diameter, i.e. more mass of conductive material per length, is, in resistors as well as in other signal paths, a more important factor to the level of distortion than the length, a bigger size necessarily means better performance.
In amplifiers resistors are used to direct the flow of power supply and of AC signals within an amplification section.
Resistor values may vary from 0.1 Ohm (W) up to 99 megaOhms. On each resistor a three color band code is printed indicating its value. black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, purple=7, grey=8 and white=9. The first two bands form a two digit base value, while the third band indicates the following number of zeros. The third band may also be gold or silver. A third black band would indicate a value between 10 and 99 W, a third gold band a value between 1 and 9.9 W (x0.1) and a third silver band a value between 0.1 and 0.99 W (x0.01). A fourth band usually indicates the value's "tolerance", gold for a 5% maximum difference between printed and actual value, silver for a 10% maximum difference. Resistors come in series of standardised values, the E96, E24 and E12 series. Generally only E12 values are used. Within E12, the two digit base value can only be one of the following: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82. These values come in any number of zeros.
TRANSISTORS may be described as analoguely programmable resistors, that have three leads, an input, an output and a data input. A "program current" is set on the data input, as a function of which current will be allowed to pass from the input to the output. What kind of function depends on the type of transistor. Usually it will be a linear function, simply multiplying the program current. If that program current would be an AC signal, its amplitude would be multiplied, i.e. the signal would be amplified.
There are two types of transistors. On both types the data input is called the basis. On PNP transistors the input (positive) is called the emitter and the output (negative) the collector. On NPN transistors the collector is positive and the emitter negative. Current can not flow from output to input.
Transistors have a bunch of specifications, the type (PNP / NPN), the material (germanium / silicon), the order of the leads, the package (the standardised metal or plastic mould surroundig the transistor, and the cooler plate), the heat dissipation in Watts (P), the Hfe value (the multiplying factor), the Ft value (maximum or terminating frequency) and last but not least the "use", because a transistor may have all the right specs, but if it was made as an RF switch it cannot be used as an audio amplifier.
Because transistors are very vulnerable, the voltage allowances between the individual leads (Vbe, Vcb and Vce), as well as the maximum current it can handle (Imax) are primary specifications as well. If these values are only slightly exceeded, the transistor is likely to burn instantly. The same applies to ICs and chips, which are even more particular, specifically those at low voltages.
This already shows that you cannot just ask for a type of transistor, you must ask for a particular one. Therefore every transistor that is manufactured is given a unique number. Transistors are produced in three world regions, North and South America (numbers starting with 2N), East Asia (numbers starting with 2S, usually omitted) and Europe (numbers starting with a letter). Transistor numbers are listed in transistor guides, that list the specifications of tens of thousands of transistors, starting from the 1960s when they were first produced. Today these specifications can usually be found on the internet.
THE SCHEMATIC
The above schematic is horizontally symmetrical, showing identical sections for each of its two channels.
For each channel, a pair of identical NPN medium current audio transistors, with an amplification ratio (HFE) of 250 minimal, are used to consecutively amplify the incoming phono signal to line level.
Power is supplied by a 9V battery. A single capacitor of 100 µF is used as an additional power supply for both channels. Two capacitors of 47 µF on the emitters of the second transistors are used as local power supplies.
The two NPN transistors are supplied with DC power of the positive kind via their collectors, past resistors of 120 kW and 12 kW resp. After signal amplification, current is released to the negative side via their emitters, past resistors of 470 W and 2.2 kW resp.
The output signal of each transistor is received from their collectors.
The phono signal first passes, or rather, does not pass a 56 kW overload safety resistor onto signal mass and negative power. Next it does pass a 1 kW mitigator resistor.
Subsequently it passes a 1 µF input capacitor. The input capacitor separates the phono cartridge from the phono amplifier electrically, allowing the latter to run at a higher voltage, without DC flowing back into and burning the cartridge, while connecting them logically, allowing AC to be accepted from the cartridge.
Thus the AC phono signal, having the same amplitude but at a higher voltage, reaches the basis of the first transistor. The purpose of which is to increase the amplitude, not the voltage level at which it occurs.
Inside an amplifier (section), that will always run at a particular (non-zero) voltage, AC signals can only exist as fluctuations of that voltage level, i.e. of an already existing general flow of current that, in this case (NPN + NPN), will always be greater than the greatest opposite fluctuation of the AC signal, so the flow of current will vary in measure, but never actually in direction.
As a linear function of the AC signal on the basis, current now passes through the first transistor's collector towards the emitter, at a rate, i.e. with an amplitude that is increased by a (HFE) factor of 250 or more.
Part of the first transistor's collector current is coming from the basis of the second transistor, the exact amount or ratio of which is determined by the value of the collector's power resistor, which is 120 kW. Note that this will cause a negative copy of the original signal to arrive at the basis of the second transistor.
In the second transistor the amplification process is repeated, only now with a higher input signal on the basis, which is then amplified by a factor of 250 once more.
Finally the relatively large power requirements of the second collector will resonate on a 10 µF output capacitor, the exact amount or ratio of which is determinded by the collector's power resistor, which is 12 kW. Note that this will cause the negative copy of the signal to become a positive again. Not that it matters, it is just a phase shift.
To prevent oscillation, a small 50 pF capacitor is put between the collectors of the two transistors, and a 470 kW resistor between the basis of the first transistor and the emitter of the second.
The RIAA correction section consists of two resistor / capacitor pairs, in the top centre of each channel section, one pair of 15000 pF and 220 kW, and a second of 4700 pF and 18 kW, connecting the emitter of the first transistor with the collector of the second.
AND BEYOND
This does not, of course, fully explain the mechanics of the phono amplifier, and new and useful questions would arise in nearly any creative mind to contemplate them, also considering that, at the speed of light, all constants will become one (1), all quantities will become one (one) and all forces identical phenomena. But it does begin to describe it.
Note however that the flow of current is a completely virtual concept inasmuch it will always go from positive to negative, while any electron in the universe will only go from negative to positive. Which puts constraints on the applications of the general electro-dynamical model in that it can only be used to explain aspects of electro-dynamical phenomena that are actually reciprocal.
Whereas on the level of perception of common electrical circuits the difference between the quantities V and I often seem anything but perfectly distinct, they do in fact project on distinct phenomena occurring between force fields on the subatomic level.
Considering force field interaction, a few things can be established. In the first place, it takes two force fields to have an interaction, without which the existence of the universe would be completely arbitrary. So, by definition, force field interaction is a mass, or at least a multiple field phenomenon, and any scientific model staying with the singular aspects of force fields would be inherently useless. A useful model would require at least two (2) fields.
Secondly, any force field in the universe will only interact with fields of its own species. To all other species it is completely neutral, to the extent that its existence cannot be established, and might as well be in another dimension, or another level of the universe, and probably is. Note that these truths have a limited physical application, and by no means could apply right down to the religious level, or even to the conceivability of such an event, where many different types of interaction would be involved.
However all force fields do share in common that, in 3-dimensional space, they expand with the speed of light, and the strength of the field diminishes from the centre 2-dimensionally rather than 3-dimensionally. Due to the latency of the speed of light, inside moving force fields Doppler-like effects are to occur to the field strength, which f.i. would explain that a gravity field moving at light speed would be infinitely heavy at the front, but completely weightless at the rear. The same would, of course, apply to other fields.
Keeping in mind that their centres are empty, and that the object of any force would be the force field as a whole, in all its infinity, such centres could be experimentally extrapolised, in that the distance between them would be indicative of the level in which the spheres of influence of the respective force fields would be sharing the same space, and virtual plains of intersection be plotted, of an infinite size, the centre point of which would have a particular level of reciprocal seizing effectivity, with a differentiated maximum density of field lines, showing the level of attraction or rejection between them, at a particular point in time.
Which would allow us to delete the current subject / object model as used in force field physics, and pass on to a more useful subject / subject model, without any implicit notions of hierarchy inherent in the subject / object model, whichever way around.
At the point of intersection of electrical force fields, i.e. at a particular point in time, the field line density is corresponding with the voltage as measured in electrical circuits. The number of force fields interacting, dramatically increasing the amount of kinetic energy in that part of the universe, is corresponding with the current.
Voltage and current may be at least partly dynamical phenomena in free space, in disconnectable electrical circuits they are typically kept static, as without current the voltage will not change either.
Due to the materials used in common eletrical circuits, that feature an abundance in free electrons, even when the circuit is connected we are immedeatly faced with the mechanics of congestion. Instead of applying to the behaviour of individual particles, V and I are now properties of a flow of streaming particles that act as one body, applying to locations in the circuit.
Typically in a 1 square mm cable and at 1 ampère an individual electron will move at a speed of 1 mm / second. This doesn't seem to be harmful to anyone. But that speed is just a fractional part of a chain reaction that expands with the spead of light, which acting as a whole, and there being 1 coulomb or free electrons in every cubic mm of conductive material, could definitely kill us.
SHIELDING
Before and during amplification both phono and line level signals are to be properly shielded to fight signal distortion.
Whether cinch or XLR is used to connect audio decks, signal protection through shielding is achieved by creating a chain of interconnected cages of Faraday, that eventually connect to mains null (cinch) or to mains ground (XLR), because a cage of Faraday must be connected to ground to actually become one. The chassis of the decks are used as cages, which are interconnected by the shielding of cables that act as cages as well. To be able to connect to mains null in cinch systems, shielding and chassis are connected to and identical with the signal mass and negative power.
Inside an amplifier, the signal mass directly connects to the negative pole of the power supply, and in many cinch amplifiers even directly to the chassis of the deck. The latter actually makes the chassis part of the low voltage circuit. This is normally harmless, since it will be at the negative end of the circuit and any current in it will directly drain away to mains null, resulting in zero voltage. It may even improve performance, but some reverence should be observed when connecting such decks to an earthed outlet, unless you like unpredictable results, since they were clearly not designed for this. Generally it will even work.
On XLR systems the positive and the negative complement of the audio signal are carried over two separate shielded cores, and the XLR connector has three poles. The negative signal complement (mass) connects to negative power only, and the shielding connects to the chassis only. They must be kept stricktly separated through all decks connected, and the decks should draw power from earthed outlets, since their chassis are to connect to the mains ground wire for the shielding to become effective.
The above schematic is cinch based but could theoretically be used for XLR as well. In that case the connection of signal mass and negative power to chassis (bottom right in the schematic) should not be made. Instead, the chassis that would hold the phono amplifier would have to be electrically isolated from it and be (somehow) connected to the XLR cables' shielding, both in and out.
The cinch and XLR story is pretty straightforward and among other things explains why the systems should not be mixed, that is, with the kind exception of the cinch connected MM / MC turntable. Because of its extremely low voltage, the MM / MC phono signal is extremely succeptible to electro-magnetic interference, at least before it is brought up to line level by the phono amplifier.
For a cinch connected turntable this means that, BEFORE the phono signal is brought up to line level, the negative complement of the phono signal created by the cartridge (phono mass) cannot be used to additionally drain away the interference caught on by the chassis of the turntable, by connecting the two as is usual in other cinch oriented decks. Due to its low voltage, this would cause an intolerable signal / noise ratio on the positive complement of the phono signal. Don't ask me why, cause I dunnoh.
However, for the cinch turntable chassis, specifically the tone arm and the shielding of the tone arm wires outside of it, to become part of the cage of Faraday system and hence effective as shielding, it must be connected to the cage system by another means than the phono mass. Therefore every cinch turntable has a separate ground connector, that connects to an identical provision on the phono or integrated amplifier.
Note that this makes for a peculiar protection sequence in cinch turntables. On the turntable, the tone arm wires are shielded by the tone arm, and subsequently in the turntable by some other form of shielding, whether it be a wick, metal foil or the deck itself. But outside of the turntable, in the cinch cable, the phono signal is shielded by the phono mass again, which is eventually to connect to the turntable chassis, but not beforel the phono signal has been preamplified, or at least has reached the preamplifier.
In fact, the cinch turntable is an XLR component in an otherwise cinch based audio system. And it would be optimal, and quite feasable, to actually use some form of XLR cabling to connect it to the phono amplifier's input, while using cinch cabling for the phono amplifier's output, in case you were to build one yourself. As long as phono mass and shielding / chassis are not to connect before the phono amplifier, and ideally even at its output end. Note that as a whole the system would remain cinch based, and that none of the connected decks is to connect to an earthed outlet.
Typically you would isolate the XLR terminals from the phono amplifier's chassis at the input end, and make shure to connect the cinch terminals with the chassis at the output end. You would then have to make XLR terminals on your turntable. Instead of two, you would now have four shielded connections, two phono signals, two phono masses and a shared shielding that is connected to the tone arm, the shielding of the tone arm wires inside the turntable and the rest of the turntable chassis. Of course, if you want professional results, these would all have to be soldered connections, at least for the XLR connections carrying the phono signal.
To top it off, phono cartridges have specifications as to which terminals are their signals and which their signal masses. Though one is a negative copy of the other, it is not in fact arbitrary, since both coils are to one end connected to the cartridge chassis in order to drain away, any outside magnetic interference. This is why the catridge chassis should be isolated from the head-shell, to prevent phono mass and turntable chassis from being connected prematurely. If you are in doubt, switch the head-shell wires on the cartridge to determine which orientation produces best results. There should be an audible difference.
They used to have crystal cartridges that directly produced line level output. Next picture.
RIAA2D.BMP