A Pleiades music transformer of unbelievable quality.
The front end of a recording system or perhaps any system is the most important part. Any fault there (artifact, noise, hiss etc), will be multiplied by the following stages of the system. Using an analogy, we, humans are what we eat and think. The quality of raw ingredients will dictate much of our performance or happiness in life.
This is on making the Pleiades transformer. Its development, making, use, selling is open source. Same as on the Pleiades filter and any other Pleiades concept.
It can be wound by anyone, anywhere. Sun light helps watching clearly. It can be handwound under the sun.
The number of insulated wire turns of the primary winding dictates the low frequency cutoff. It can therefore conveniently be adjusted to compensate the bass proximity effect, Fletcher-Munson curves, voice effort curves etc. This reduces the number of turns needed so it becomes a joy to wind. And the result is a joy to listen too. Amazing, clear focused sound, spot on the application, with unheard of signal to noise ratio.
It is based on principles discovered hundreds of years ago by the great masters, Ampere, Faraday, Maxwell..., so no patents are infringed. Simplicity of its making is possible by recent Nanocrystalinne magnetic cores of tremendous relative permeability such as the Magnetec Nanoperm which is a great step forward for mankind.
The Pleiades transformers can be used for stepping up the signal of a microphone, moving coil cartridge, ... , with or without Pleiades 3V battery electron tube or JFET state of the art low noise pre preamplifiers or any other amplifier you would like or you would like to make.
Why transformers on 2017?
Because:
They are balanced or even make an unbalanced signal balanced. They also isolate electrically.
They reject rf, hum, low frequency and other cable induced noise.
They increase the signal to noise ratio by stepping up the signal voltage passively.
They electromagnetically damp the moving coil or ribbon microphone membrane making possibly the best pop filter on the planet.
They can compensate the proximity bass increase effect.
They complement nicely electron tubes of JFETs being in an analogous way the first lens of the telescope or electron microscope.
They match any impedance to any impedance by the square of their turn ratio. For example a turn ratio of 4 means a 16 times increase in impedance.
They are possibly the best way on the planet to mix signals (hybrid transformers). Better so than mixing resistors. (In electronic engineering the correct word is adding. Mixing means multiplication as in amplitude modulation, ring modulators etc. The unfortunate use of the word may have come from the use in some languages of the word mixer to mean blender. Mixers are nice to make healthy fresh juice).
So with the aid of signal transformers one can make a state of the art preamplifier using just one or two electron tubes or JFETs. The schematic can be very similar to the simple and wise schematic of the Neumann U47 microphone. Less is more and with just a few top quality components you can have a world class sound quality preamplifier with unheard of signal to noise ratio.
And there's joy in making it yourself.
Don't be afraid to use dynamic microphones ie moving coil microphones. Fear does not exist anyway. And dynamic microphones are used for vocals in the studio or outside by Bono, Sade, Stevie Nicks (Fleetwood Mac), Brian Wilson, Phil Spector, Amy Winehouse (ribbon)...
Since fear does not exist do not be afraid to use omnidirectional microphones. The song Close to You sung by Karen Carpenter as well as the other Carpenters songs were recorded by a microphone (next to the control room glass) stuck at the omni setting. It was a condencer U87. The techniques you will use can also make any dynamic (moving coil cardioid or omni) microphone sound as sensitive and revealing as any condenser as it will be active with a simple world class amplifier such as the Neumann U47.
Fear does not exist and inexpensive microphones can be tried. As an engineer from Abbey Road might have said: The secret of recording is the right microphone at the right position.
Increasing the turn ratio a lot reduces bandwidth quite much on any transformer. This seems to be a nice thing as it makes flat frequency responce not from microphone to loudspeaker but from the vocal chords of the actor or singer to the listener's brain, (see other euroelectron posts on the "secret" of Hollywood).
So how are Pleiades transformers made?
You need:
Great quality and simple food for yourself, for being happy, healthy, and have free time to make them. More on other euroelectron posts.
Enameled insulated wire for the primary and secondary windings.
A Magnetec Nanoperm toroidal (ring) core. The toroidal shape is the most magnetically efficient on the planet. It contains the magnetic flux inside. The flux does not leak outside. Outside interfering magnetic fields are difficult to leak in...
The primary winding number of turns dictates the low frequency cutoff.
Why? Because for example at 0 frequency you are left with just the resistance of the wire as the reactance which is proportional to frequency has fallen to zero. This short circuit loads the microphone and since it has an output impedance of 200Ω its output drops to nearly zero. The same reasoning applies for any frequency. It is not that a trasformer does not pass low frequencies. It is that they drop right at the microphone output terminals 2,3 when the trasformer is connected. If you understand this you have already mastered most of the art.
Any cutoff frequency can be made by choosing the primary inductance which is of course affected by the square of the number of primary winding turns. To repeat, frequency selectivity comes from the potential divider created by the microphone internal series resistance and the shunt reactance of the primary winding inductance.
Pleiades transformers are not only electrically balanced but geometrically balanced, symmetrical too.
Firstly the thin wire of the secondary is wound which needs many turns.
For the sake of beauty, symmetry and balanced operation just one layer of winding can be wound on the toroid until all the color of the core is covered. We then do very carefully a double knot. The end wires are twisted. Their ends are then heated with a soldering iron and tined (openning windows, attention to fumes etc). The secondary is ready.
A piece of wooden stick a bit thinner than what you can find at Startbucks can be used to handle all this long wire. The top and bottom is filed to a suitable shape so that the wire can be wound to this stick along its length. We then use this stick to wind our secondary by passing it through the hole of the toroid for every turn.
The stick passes through the toroid so that many turns can be wound without messing with a long wire dropping on the floor.
Each turn can be placed adjacent to the previous.
Then the primary is wound. It needs much less turns so it usually can be wound directly without the piece of wood.
As mentioned the number of primary turns dictates the low frequency cutoff right at the output of the microphone. We may do anything we like. Compensating for the proximity effect of any mic for any distance.
The turns ratio is the step up voltage signal ratio.
The turns ratio squared is the impedance conversion ratio. For example a turn ratio of 10 gives a voltage increase of x10 and an impedance increase of x100.
This is due to the principle of conservation of energy. Power input must equal power output. Power is voltage times current. So Vin x Iin must equal Vout x Iout. Zin equals by definition Vin/Iin. And Zout equals by definition Vout/Iout. By rearranging mathematically these relations one proves the turn squared impedance relation.
The Nanoperm core is so good that one should be able to make transformers of tremendous bandwidth.
But for correct reproduction to our brain perception than to a loudspeaker a much lower bandwidth may be needed.
So the turn ratio may be even further increased and with it the signal to noise ratio and naturalness of sound.
Double knot of the primary end wires as much near to the magnetic core and it is ready. The microphone is connected to the primary. The secondary is the higher voltage high impedance output much like a condencer microphone capsule output. So you may treat it as such by connecting it (usually through a capacitor) to the grid of an electron tube or gate of JFET. Same practice as is done inside a Neumann U47. You may find Pleiades schematics based on the Neumann U47 that operate with electron tubes and 3 volt battery only as the there is no need to polarize a diaphragm. Nature is doing the analog of this by the permanent magnetic field from the microphone magnet. The Pleiades V series prepreamplifiers are even simpler designs than the U47 amplifier, their development is open source and schematics can be found on euroelectron blogspot.
Using transformers is equivalent to instantaneous analog tape recording and playback. You have nature working freely for you. Moving electrons, oscillating electrons, spinning electrons, dancing to the music signal. Moving electrons create a magnetic field on space around then. Transformers are passive like ancient weight lifting levers. Like a gear box. Like a hydraulic car lifter. The same equations apply. For example the ratio of the diameter of two gears is equal to the ratio of torque and inverse ratio of angular velocity. And all these do the most important. Impedance matching so that least energy is reflected back and most energy passes through.
References:
Enchiridion - Epictetous - Free online PDF
The Feynman Lectures in Physics - Feynman, Leighton, Sands - Caltec - Addison Wesley
Electromagnetism - Grant, Phillips - The Open University - Wiley
Introduction to System Dynamics - Shearer, Murphy, Richardson - MIT - Addison Wesley
Coil Design and Construction Manual - B. B. Babani - Bernard Babani publishing LTD
Magnetis Circuits and Transformers - E.E. Staff M.I.T. - John Wiley & Sons
Electronic Transformers and Circuits - Reuben Lee - Wiley
Applied Electromagnetics - Plonus - McGraw Hill
(The "secret" of Hollywood), Sound Picture Recording and Reproducing Characteristics (for flat frequency responce from vocal chords of actor, singer, to listener's brain) - Loye and Morgan - JSMPE - Hollywood
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