Figured Bass Orchestra

Could an orchestra be made where all musicians have perfect pitch and play without reading notes, by understanding figured bass?


It would be like  the most beautiful instrument playing on its own.


They could hear something and play it or compose themselves in real time thinking fighter bass.

Pleiades Magnetec Neutrik iPad microphone setup

It would be great to make a Pleiades microphone pre preamplifier as follows:


Everything inside Neutrik XLR modules:


Inside a Magnetec 073 nanocrystalinne core,  few primary turns for bass proximity compensation.


Capacitor coupling of secondary to a K177 JFET.


Everything inside the Neutrik modules and power and drain resistor supplied by the iPad headphone mic connector.


This would provide at the same time: proximity compensation for next to mouth mic work, make up gain, extremely low noise, ie great signal to noise ratio, portability, crystal clear sound.

Maximum Information Extraction

If a Pleiades microphone transformer with Magnetec 073 core, capacitor couples the grid of a positive biased EF183 at 5V anode voltage and less than 3V? Heater voltage, a microscope equivalent is created as at such small electron speeds the electron tube is extremely quiet.


Maximum information extraction.


Makes wonders on dynamic and ribbon microphones.

10k to 600 ohm audio transformer microphone step-up step-down impedance hi-z

Just tried this step up transformer bought from TechnoFix on eBay, TL019-R 1438.


Sounded amazing connected to the Pleiades V4 pre preamplifier.


The coupling capacitor to grid on V4 is 220nF. It is very important to capacitor couple to an electron tube grid so that the valve's grid is free. (Not made by force to assume a potential).


The primary inductance of the transformer is 100mH at 1028Hz and 165mH at 97Hz making wonders at compensating the proximity effect of the MD421HL and SM58 (made in Mexico) used. Mic mouth distance approximately 1 in.


Connecting the transformer to the grid of the EF183 made the high frequency response high but not high enough to sound over detailed and unnatural. It seems therefore to compensate the high frequency proximity effect due to the obstacle effect too.


Secondary inductance is 7H making a 1:8.5 step up.


Bravo to the designers, a giant killer!

Who said that microphones should have a flat frequency response?

Perhaps nobody did.


Truth is that what counts is not flat response from mic to loudspeaker but...


Flat frequency response from the vocal cords of the singer to the brain of the listener (explained on the Hollywood paper referred to in older posts).


Apart from this are proximity boost effects at low and high frequencies which must be compensated.


All these effects may explain why a "lesser" mic or input transformer can be a giant killer.


The record industry uses Pultec filters to this end but why not producing a mic where the sound is already there?


Be prepared that frequencies below 1KHz for example must be reduced if a directional microphone is used at next to mouth distance. Similar apparently crazy things must be done at the high end of the spectrum
More on the following posts....

How does a Pleiades filter work?

A Pleiades filter is just an inductor in parallel with the signal.


By reducing the winding turns the cutoff frequency is increased and even closer mic source distances are possible. The same principle can be applied to a Pleiades transformer ie reducing primary turns thereby reducing primary inductance and increasing cuttoff frequency therefore making the mic focus at a smaller distance. Decreasing primary turns has the added advantage of automatically increasing the transformer turn ratio. So this iautomaticaly makes up gain. The core used to make the Pleiades inductor or transformer is an extremely high inductance index nanocrystalinne cores made by Magnetec. This makes possible Pleiades filters with very few number of turns. Example of a core is Magnetec Nanoperm 073.


A Pleiades filter can compensate for proximity effect even at a next to mouth mic distance minimising feedback at PA systems and virtualy eliminating pop and wind noise although its a good idea not to remove the microphone grill as it does much wind noise reducing work. After filtering the signal is so clear that one can hear the greyest detail from a voice. If high frequency cutoff is needed for reasons explained on other posts this can be done by a Pleiades high cut finger which consist of just one capacitor in parallel with signal.


A Pleiades transformer with its high impedance can drive the gate of a JFET or the grid of a vacuum tube trough a calling capacitor. On following posts Pleiades pre preamplifier are  described including an extremely low noise electron tube one powered by 5V only at the the anode (plate). This is achieved by large Megohm resistor from Anode to grid to free electrons.


Such Pleiades pre preamplifiers next to the output of the microphone transformer make dynamic or ribbon microphones so sensitive that play condenser microphones in their own game.


How does a Pleiades filter work?


The microphone output impedance is in series with the inductor and together form a potential divider.
The inductor impedance as usual increases with frequency and makes the microphone output increasing with frequency at 6dB per octave compensating the proximity effect. After the cutof frequency the impedance of the inductor becomes so high that there is no voltage drop at the mic and response contineous to be flat.


How does damping work?


At low frequencies the droping impedance of the inductor (which becomes just it's winding resistance at zero frequency) makes a large current flow through the coil (shorts circuits the coil at LF). This makes the coil behave like a loudspeker but moving in the oposite direction to the cause (sound wave, blast, pop etc) this is Lens  law in action being a represantation of concervatiin of energy for if this force were of the same direction as the cause we would have amplification for free, imposible.




This is the same principle as a brake in electric cars by short circuiting  the output of the motor when the car is running.



Another way to put it, it's kunitic energy converted to heat.



This creates a very effective pop and wind filter.
Wanted sound is  unaffected as at voice frequencies the impedance of the inductor (which increases with frequency) has become large as to no longer be a load on the voice coil, letting it free to move at the pristine quality of your voice.

Compensating for the 2 proximity effects on a Shure SM58

There are 2 proximity effects (when mic is close to mouth), one the increases bass  and the other that increases treble called the obstacle effect


Natural sound from vocal cords to brain of listener for a Mexico made  SM58 next to mouth were obtained as follows:


SM58 was shunt with 19.5mH !  i.e. low cut at 1.6KHz and 15nF shunt to the Pleiades V4 (EF183 pre preamp with 4 AA batteries) output to reduce treble boost, sibilants, saliva noise (sometimes desirable). Added advantage is the reduction of any hiss left and rounding waveform curves should instantaneous peak limiting  occurs at the electron tube, thereby preserving subjective volume due to natural harmonics produced while objectively limiting the signal.


Signal path used:


Voice - SM58 - Pleiades 1:7 input transformer, 19.5mH primary L - V4 (+ve bias from plate to grid) - 15nF across output - Realistic Disco mixer mic in - pad before headphones - Sennheiser HD560 - ears - brain