A book with a great chapter on class A amplifiers

Communication Engineering - Everitt


(Can be downloaded from archive.org)


Or bought on eBay. Amazon for so little.


Nice explanation on the effect of external components in reducing the bandwidth of an electron tube which is MHz anyway without any feedback.


For understanding these effects and much more see also the modern book:


Electronics, a systems aproach - Neil Storey

Most of the chords on our planet in a few seconds

An easy way to crate them is keeping a melody part constant while having the bass descending the notes of the scale. (Pedal melody) (Step bass)


Brilliant examples are:


The intro of Julia - Pavlov's a Dog


The outro of Chi Mae - Morricone (make shure you watch the original onYouTube)
The chord before the last is the brilliant G major 7th. Ie F sharp played continuously high on the violins and Bass G. The last chord is where the bass at last becomes F sharp itself.


Bibliography:


Bach Bass Rules (free PDF)

The physical meaning of an integral in mathematics

It is a sum of infinte terms that are infinitesimally small.


So the total is a finite number.


The integral of acceleration is velocity. Time is the variable. Ie acceleration as a function of time or a(t).


The integral of velocity is distance.


The dirivative (rate of change) of energy with respect to time is power.
The integral of power is energy.


Perhaps the most brilliant description of an integral (even in vector form) with great pictures is in the Electricity and Magnetism, Berkeley Physics  Course - Purcell - Harvard University


Understanding the integral is a key to understanding electric potential,

Some books on electricity and magnetism

The ones on the previous post plus


A treatise on electricity and magnetism - Maxwel (himself) - Dover

Definition of electric potential

One of the most difficult definitions perhaps on the Universe. It goes something like the work done by the (variable with distance force of the field to the charge) when it is moved from a point A to infinity devided by the charge. A can be any point in space even the terminal of a battery. It can be a point in space inside an electron tube. It can be a point anywhere in the universe.


See: Berkeley Physics Course - Purcell - Harvard University


See also: Feynman Lectures in Physics - Feynman, Leyton, Sands (there is an electric field of 100V per meter above the earth's surface. But as soon as we are there our body changes the electric lines of force as we are grounded. A high impedance field. At a few kilometers above earth the voltage is really large. Hence we have thunders ie big sparks).

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The bias voltage of the 7586 Nuvistor when Pleiades V6 is operating

Not measured yet, but it should be negative. Close to 0 volts.


Later addition: Measured! It is -77mV with a Pleiades bias resitor of 6MΩ. More details on the nearby post:


http://euroelectron.blogspot.com/2018/07/as-it-seems-grid-bias-is-adjusted-by.html

Considering a prototype layout of Pleiades V6

This is on an one electronic valve or electron tube microphone booster preamplifier powered by just one AA size 3.7V battery including anode. In particular on construction considerations of the Pleiades V6 ultra low noise microphone head amplifier. Everything including the battery and electron tube or electronic valve to be inside an elegant small size enclosure.


Before making the prototype a hardwired version may be made but it will be in an already existing bigger box.


It was dreamed that a rectangular aluminum prototype caused setting up details in a studio environment. The microphone to be connected was the Sennheiser MD441 U3. Everything has to be ready with minimum connections or delay. The microphone connected to the low noise Pleiades V6 booster amplifier and the output from the Pleiades V6 feeding everything else. Fletcher Munson, voice effort curves can be internaly selected by a switch.


The Hammond octagon orange colored aluminum diecast enclosure is a very promising option.


It is slightly bigger than a rectangular box.


But the main advantage is symmetry and the convenience of 8 faces available for each internally mounted component of the microphone booster amplifier. No sharp edges. Another advantage is that the connections from battery holder to output transformer to electron tube will be very short. The only problem so far is that the inside of the enclosure is not painted. It would look so much better at least as good as the outside. Why orange? A beautiful color reminding the calmness of sunset.


How can each one of the 8 faces be used?


In reference to the Pleiades V6 schematic:





Rotating clockwise...


Side (or face) 1 supporting the Bulgin AA battery holder, to be housing a 3.7V li-ion battery. A 700mAh charge should give many hours with the Nuvistor 7586 electron tube consuming 100mA. The EF183 should consume double power as the underheated heaters might be at 200mA. A fuse holder should be in series with the battery holder.


Side 2 supporting the output transformer ring core. So connection of the thin Vb wire will be right next to the battery holder + terminal.


Side 3 an electron tube 9 pin base. So that the other thin wire of the output transformer is connected right next to it. The unusual concept here is that the pins will be used as stand off pins for soldering the Nuvistor base. So the Nuvistor electron tube can be inside the box. A 9 pin electron tube can be connected externally. But in any way the noval socket will generally serve as communication interface to the outside world. For example measuring potentials or with 9 pin adapters almost any electron tube can be connected, including EF14, ECC88, 6SK7 etc. So very low anode voltage performance with Pleiades bias of almost any electron tube can be accessed fairly quickly.


Side 4 supporting the ring core of the input transformer. Again this is next to the electron tube so that the thin hi Z wires can be made short.


Side 5 the mic input Neutrik female XLR connected to the 25Ω primary winding. Great for the Grampian DP4/L microphone etc.


Side 6 the mic input Neutrik female XLR connected to the 200Ω primary winding. Great for the Sennheiser MD211, MD441, Electro-Voice RE15, Shure Unidyne III, Beyer M55, Shaub Lorentz SM200 microphones etc.


Side 7 the circular Bulgin or Velleman recessed aluminum, or inox push button. It will only control power to heaters for soft on or off. Anode voltage is always supplied.


Side 8 the boosted mic output Neutrik male XLR connected to the output transformer secondary.


Note, input, output is balanced. The Pleiades bias resitor may be variable for adjusting bandwidth. The output impedance using the EF183 and a 10:1 output trasformer is approx 300Ω. It may be higher using the Nuvistor 7586. No such measurement has been made yet.


This may be possibly the first true portable electron tube amplifier operating with just an AA size battery for many hours and all components housed inside a small elegant box. And ultra low noise due to low anode voltage, absence of secondary emission effects, low cathode temperature therefore low anode internal resistance thermal noise.


There should also be a switch called FMVE, ie Flethcer Munson, voice effort compensation for flat frequecy response from producer's brain to listener's brain. It would connect a Pleiades (R,L) gentle slope low cut filter across each primary winding in turn.


Further reading:


The Pleiades Bias - euroelectron


A Study of Noise in Vacuum Tube And Attached Circuits - F. B. Llewellyn - Proc. I.R.E, Vol. 18, Number 2, February 1930


Operating Features of the Audion - E. H. Armstrong


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE

Hello

Wishing to all of you being well.

Hello to Germany

Hello to Netherlands

The 3 per cent rule (just hypothesis)

Just a hypothesis.


3% of our books are really worth. 3% of somebody's vinyl records or CDs.


3% of all books?


etc

Interesting ERSA history

https://www.kurtzersa.com/electronics-production-equipment/about-us/ersa-history.html

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BBC, Olson ribbon microphone filter, equalizing circuit

Assuming it is built in an enclosure or XLR adaptor.


From mic in pin 2 to mic out pin 2 a resistor.


From mic in pin 3 to mic out pin 3 a same value resistor.


In parallel with each resitor a capacitor.


By choosing values very high pass (shelving) can be obtained. Or gentle low cut ect.


The Haden BBC books shows 500Ω for the resistors and 2μF for the capacitors.


(It had been tried a long time ago with the Grampian ribbon GR1 /L, the sound was not quite as expected, a  possible cause could be the fact that the mic is 25Ω so different values should have been tried, or that different mic source distance should have been used.)


It is also possible that for some reason inductor filters sound better than capacitor ones. Great examples of such filters can be found on the Olson paper including one with an inductor in series with a resistor. L or R,L filters are seen connected in parallel with tapings of the ribbon microphone internal input transformer.


See also the Pleiades (R,L) gentle slope low cut, high pass filters with inductors and resistors. Such filters are inside AKG D1000, (possibly inside Senheiser MD421, MD441), and inside the Electro-Voice 642 academy award winning microphone etc. See datasheets at www.coutant.org.


References:


High Quality Sound Reproduction - Hadden - page 63 - BBC


Ribbon Velocity Microphones - H. F. Olson - JAES - June 1970, volume 19

A variation to the Pleiades V6 amplifier

Your own risk.






What if the secondary of the input transformer is connected to a positive potential such as Vb (or even anode?) then the other terminal of the secondary connected to the Pleiades bias resitor. The other side of the resistor to control grid. A capacitor then connected in parallel to the grid Pleiadss bias resistor.


So this is grid leak bias but connected to a more positive terminal than the cathode making again electron tube operation possible at very low anode voltage.


There may be rectification side chain compressing effect at high levels. Just what happens when the Neumann U47 microphone VF14 electron tube circuit is overdriven and bias changes automatically reducing gain. See other euroelectron posts. The release time may be fast since the input impedance looking at the grid when Pleiades bias is applied is typically 100KΩ. So the interested reader sound find more suitable examples on the original U47 Neumann circuit featuring resistors of many megohms, Western Electric small signal amplifying circuits, and on the book Communication Engineering - Everitt in the section of resistance coupled, transformer coupled amplifiers.


The grid leak bias is also used for example on Emerson vintage electron tube portable gramophone amplifiers for producing great bass utilizing the property of the human brain to synthesize a missing fundamental from the presence of overtones. See older posts.


Reference:


The Neumann U47 microphone BBC report:
https://www.bbc.co.uk/rd/publications/rdreport_1954_23

Other ways to make the high pass slope very gentle

See also the Pleiades L in series with R microphone filters.


Another way can be for example:


Using a JFET or electron tube in a circuit such as Pleiades V6. But with a source resistor bypassed by a capacitor of low value. So the very low bass is not amplified.


Or using a resistor in series to the bypass capacitor etc.


Such elegant slope changing techniques may be seen on FBT electron tube PA mixers, the Altec electron tube preamplifiers etc.

How to connect a microphone to iPad part x

At your own risk.


This is on using one bipolar transistor between mic and the device. The internal device resistor that supplies power is the collector resitor itself.


On the previous euroelectron post.

A one transistor amplifier connected to iPad both for reproduction and production

At your own risk.


Apn amolifier with one electronic amplifying device is perhaps the first (1907? by Lee de Forest) and miraculous amplifier. It operates in class A (electrons flowing all the time).


A classic example of such an amplifier with just one electronic amplifying device is the amplifier inside the Neumann U47 microphone. It uses the VF14 electron tube with underheated cathode.


Now back to iPad or other devices.


A one transistor class A operating amplifier can be connected to the headphone output and drive a loudspeaker. For example the Pleiadss 2N3053 driving the high impedance Philips AD5046N loudspeaker. (Construction details are found on YouTube on one transistor amplifiers). The quality is so high that it is dictated by what is in the input perhaps with no limit. The better the quality at the input the better the quality at the output. The speaker is the collector load itself instead for example of a collector resistor. This Pleiades setup is usually used connected to a Sony portable CD Walkman at its bridged to mono line output. A series resistor to the transistor base terminal controls volume. A coupling capacitor is not used but it may be needed for an iPad etc, at your own risk. Bias to the transistor is by a resistor from collector to base. A heatsink should normally be used for safety and protection including thermal runaway.


Now how about connecting such an amplifier at the input so as to amplify an external microphone and then connect to mic in of iPad or other mic in device.


So far a JFET K117 mic booster amplifier has been described on previous posts. The Pleiades K117. The drain resistor is provided by the iPad itself while supplying power too from its mic headphone socket. Various world class microphones have been connected such as the Sennheiser MD21 HN with fantastic sound quality and ultra low noise. (Many devices have an internal low cut filter).


A very low anode voltage electron tube mic head amplifier with the iPad supplying the anode voltage from its load resistor is briefly described on a recent previous post. Pleiades bias is by a high resitor from anode to grid. This schematic is essentially a Pleiades V6 schematic with no output transformer. Electron tubes are miraculous devices for production.


But transistors too. So why not connecting a bipolar one transistor mic amplifier to the iPad's input in order to boost a microphone. Again the collector resistor will be the internal device load resistor or voltage supplying resistor. The role of a load resistor is to convert the amplified output current to output voltage, by Ohm's law. (Power is exactly the same as on the usual electret microphone powering of the internal mic JFET.)


Bias can be from collector to base by a suitable resistor. Adjusting the resistor can lead to very interesting distortion for electric bass synths etc. The mic, electric guitar, etc is connected to the transistor base through a coupling capacitor. And an inout transformer may be used too. A guitar or synth may give a too hot signal. At your own risk.


The common cathode, emitter of source amplifier. The simplest and perhaps the most fabulous sounding amplifier on the planet.


Inspiration for using bipolar transistors on top quality studio amplifiers can be found on the classic Neve preamplifier circuits. Again close to the first amplifier made on our planet. The class A one stage circuit.





Bibliography:


Tubes vs Transistors (vs op amps), is there an audible difference? - Russel O. Hamm - JAES

On the Pleiades logo the dot above the i can be the button switch

It may be a beautiful Bulgin or Velleman circular button switch.


Usually such a switch only controls heater current so that sound gradual fades in or out when switching on or off. Just like switching on a beautiful AKG C12a condenser microphone with the which has the Nuvistor 7586 electron tube deliberately underheated at 5V.


Low battery voltage can always supplied to the electron tube.


Such an arrangement may be used for example on the Pleiades V6 circuit.

Does a beautiful slim battery powered soldering iron exist?

For example taking advantage of li-ion slim hi capacity batteries?


Or using AA batteries one after the other instead of one next to the other so that it is nit large in diameter?


By ERSA which is a great company?

Hello to the United States and Polland

How would a 3 dimensional Pleiades filter sound like?

It may be strange but in engineering we use phasors or rotating vectors of 2 dimensions.


This is because we have resistance which is a real number and reactance which is an imaginary number (see previous posts). They have a phase difference of 90 degrees. Resistance dissipates energy, inductance or capacitance stores and releases energy.


No 3rd dimension?


Does nature only have energy dissipation, energy storage or release for passive systems?

Bonjour à France

How does the Pleiades (R,L) filter operate?

It is an inductor in series with a resistor. Hence the name Pleiades L,R or R,L. The free ends are connected to pins 2,3. Ie right at the mic output or head amplifier input.


At some low frequency (how low depending on inductance L) the impedanc of the inductor becomes 0Ω. It is more correct to say the reactance of the inductor is 0Ω. Ie the impedance of the R,L filter is (R,0Ω). If there is no R the impedance is (0Ω,0Ω). The magnitude of this vector ie the magnitude of impedance is 0Ω. So the microphone sees a short circuit and there is a complete voltage drop at its output due to the fact that it has a finite output impedance usual 200Ω.


As frequency rises the reactance in ohms of the inductor rises so does the output of the mic. This is at 6dB per octave. This is the max slope.


If R is not 0 we never have the case of 0 impedance or short circuit. So the bass decreasing slope is less than 6dB per octave depending on the value of R and output impedance of the microphone.


(x,y) or (R,L) or R+jL or R+iL ie complex number or vector notation is used because inductors or capacitors have a steady state phase difference between voltage applied to their terminals and current flowing through them of 90 degrees. Resistor current and voltage is in phase. Hence the notation of complex numbers to denote vectors.


In mathematics or nature 2 plus 2 does not always make 4. For examole one hand pushing against the other by 2 Kgf the resultant force being 0Kgf. If they push at other angles the resultant force is a different direction vector. Vectir addition is used to find the result. Vector angle is a different name for phase.


In engineering vectors are thought to rotate. If we take the projection in a straight line we have a sinusoidal oscilation. A sine wave.


Rotating vectors are called phasors.


Any signal can be described as a sum of infinite sinewaves. Hence the use and importance of phasors in engineering. To predict the outcome.


Since in sound engineering the end product is the lister's brain perception we must always take this too into account. Hence the importance of flat frequency response from producer's brain to listener's brain. For the frequency response of our brain perception depends on acoustic intensity (Equal Loudness or Fletcher Munson curves). (Usually between production and reproduction the acoustic intensity levels are very different. For example a very soft delicate voice is reproduced at high acoustic intensity) [Lowe, Morgan].


In order to feel the difference between resistance and reactance (90 degrees out of phase) or the difference between resistors and inductors in electricity or friction and mass in mechanical systems a favourite Pleiades example-experiment is vibrating a door by hand. As we try to move the door back and forth at a higher frequency it becomes progressively difficult (load impedance changes) and we can also feel the phase difference. The mass (or inductance) of the door is doing its thing.


Impedance across any 2 points in universe is defined as the vector of voltage applied across these point devided by the current flowing through them. It is in itself a vector. Has both magnitude and direction or phase.


Bibliography:


Engineering circut analysis - Kemmerly


Introduction to system dynamics - Searer, Murphy, Richardson -


Elements of Acoustical Engineering (or dynamic analogies) - Olson


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D.P. Lowe, K. F. Morgan


Sound and Hearing - Stevens. Warshopsky - Life science library

Why low cut filters got a bad name

Understandably many engineers can be seen in forums not liking them.


The reason why may be just this. They do what their name is. They low cut.


Pleiades filters are not made to low cut below a certain frequency. They are made to assist on the ideal of flat frequency response from producer's brain to listener's brain.


Low cut filters can be found that are 12dB or more per octave.


Pleiades filters are much less. 6dB per octave or even less if a reries resistor is connected to the coil or inductor. So much higher turnover freiencies can be used with very gentle slope.


See for example the previous post on Sennheiser MD441 U3 and Pleiadss V6 Nuvistor.

The Sennheiser MD441 U3 to Pleiades (R,L) filter to Pleiades V6 Nuvistor

It worked!


Amazing sound as expected.


Signal path, setup:


Male singing voice - Sennheiser MD441 U3 - Pleides (R,L) filter - (Pleiades L filter) - Pleiades V6 Nuvistor head amp - Sony TC-D5 Pro - Sennheiser HD580 - Singer's (listener's ) brain


The MD441 U3 comes without a bass compensation filter.


The Pleiades (R,L) is used for Flecher Munson or voice effort curves excess bass to listener's brain compensation


The Pleiades L filter was used for proximity bass compensation if needed.


It may be remembered that a straight forward Pleiades L filter connected to the amazing MD441 did not sound too well.


Today the reason becomes more apparent in practice. A high cutoff frequency had to be used but then the microphone sounded thinner or less in sound body. It turns out the 6dB slope is already too much.


A Pleiades (130Ω,40mH) filter (R in series with L and the ends connected to pins 2,3) sounds spectacular.


Without it the mic sounded bass heavy for soft singing male voice. When the filter it is connected the sound is natural. When treble boost is activated in the mic it sounded brilliant again.


Very nice sound was also with the Pleiades 145Ω,42mH but not when HF boost was activated. There was too much lack in midrange.


This is for about 4in mic distance.


When singing at 0 to 1in the bass was excessive due to the heavy proximity effect. For this case a 333mH (100Hz) Pleiades filter was cascaded after the R,L filter. (Note: there is a 6dB per octave low cut already because of the primary inductance of the output transformer and the electron tube plate (anode) (internal) resistance the value of which may be adjusted by changing the Pleiades bias resistor. When using an EF183, 6MΩ and the specific Pleiades output transformer (see previous posts) this happens below 100Hz. So if a higher inductance output transformer is used the Pleiades filter may have to be 160mH or approx. 200Hz. It may have to taken into account top that the first case of 2 low cuts may result in 12dB per octave high pas or low cut. The EMI RS106A should be 12dB per octave.)


It sounded amazing.


This is the schemagic (auto correction of iPad for schematic) of the Pleiades V6 used but with 22nF, 6MΩ Pleiades bias resistor and the Nuvistor 7586 electron tube.











Reference:


The classic Lowe, Morgan on flat frequency response from producer's brain to listener's brain:
Sound Picture Recording and Reproducing Characteristics - D.P Lowe, K. F. Morgan - JSMPE

Phantom powering of electron tube head amplifiers

At your own risk. Take all safety precautions.


A small box can contain the electron tube head amplifier.


A battery supplies the heater.


Then a centre tap from the secondary of the output transformer furnishes 48V to the circuit which can be used for anode supply.


With such a high anode supply Pleiades bias would not be required. One could connect a very high Megohm resistor from grid to cathode. Cathode is positive since it has lost electrons to the space charge. So in this way it may still be called Pleiades bias. A very high Megohm resistor should be possible and the circuit is exactly the same as the Neumann U47. An output transformer that can stand DC can be directly connected to the anode.


If a UCC85 electron tube is used then possibly the heaters too can be powered by phantom. See other euroelectron posts.


But why should one should use a mixing console on 2018? Well,they may be useful.


But it must not be forgotten that the Motown masterpieces had the rhythm section mixed in the studio, not the control room by a made up electron tube adding amplifier with a speaker so that musicians could also listen while playing. The DI output was sent to the control room. See documentary on Motown, interviews and relevant euroelectron posts.


If needed an electron tube can be powered by just 4V including heaters and anode. See Pleiades V6 head amp.

An advantage of Pleiades filters is that they can be connected one after the other

For example when each is inside an XLR female to male barrel adaptor.


This is because they are connected to pins 2 and 3 but pin 2 female is also connected to pin 2 male and same for pin 3. In other words the Pleiades filters are in parallel or shunt to the signal.


The microphone signal passes through in the usual way.


When connecting more than one Pleiades (R,L) filter does each retain its cutoff frequency?

It should be extremely easy to solar power a JFET version of Pleiadss V6

Current may even be lower than 1mA. So operation should be posible even under ambient light conditions.


Great care should given to the battery charger used for avoiding overcharging of the battery. Also a fuse should always be used in series with a battery.


Everything can be small.

Solar powered one transistor Pleiades power amplifier

It is possible with just 8mA current consumption at 12V to have world class sound quality.


An example is the Pleiades 2N3053 - Philips AD5046N combination. Operation is in class A ie electrons flowing all the time. See relevant euroelectron post.


If it is made in a box a small solar panel could be on top. Extreme caution should be exercised in the choice or design of the battery charging circuit for safety. And of course a fuse should alway be in series with battery.


The amplifier can be ready anytime charged even under ambient light conditions.  This is a bit unlikely though. As it sounds so nice it may be switched on for most part of a day.

How would a solar panel on top of an octagon box Pleiadss V6 electron tube head amp look like?

It is possible but full attention should be exersiced on the battery charging circuit for safety. All safety precautions. At your own risk. And of course a fuse should alway be in series with a battery.


It should be possible to have a electron tube or electron valve head amplifier that is always ready even under ambient light charging conditions.

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Powering the one electron tube Pleiades Electra II headphone amplifier with one battery

8V lead acid. (A fuse in series should always be used for safety).


The battery should be in the same closer to minimize voltage drop.


It may this be possible to use no cathode bias resistor making the amplifier a true only 1 electron tube per channel and nothing else.


This is the schematic link:


http://euroelectron.blogspot.com/2014/07/pleiades-electra-schematics.html


Pleiades schematics or concepts are open source

A smoothly variable low cut filter for Sennheiser MD441 U3, MD21 and other microphones

This may be made with an inductor in series with a variable resistor. The total connected to pins 2,3 ie the output of the microphone.


She also the previous euroelectron post.

A head amplifier with Fletcher Munson, voice effort, proximity effect compensation

For example it could be the Pleiades V6 head amplifier with EF183 or 7586 Nuvistor. A Altec, Jensen, Sowter or hand made nanoperm Magnetec, Mumetal, Permalloy, Supermallow etc. core manufacturers that come to mind are Magnetec, Magmet, Arnold, Haufe.





Assuming the inductances of both transformers are high enough we can go down very low in frequency. This may be useful for recording a pipe organ for example.


If an omnidirectional microphone is connected no proximity effect exists. If voice or other instrument is still bass heavy or treble heavy due to Flether-Munson (high acoustic reproduction) or voice effort curves (soft singing voice) the following passive filter can be connected in parallel ie to pins 2,3 or input of the head amplifier. An inductor L in series with R for a gentle slope low cut or high pass. And again in parallel a capacitor is series with R for gentle slope high cut or low pass. The high cut may also be done after the secondary and then a small value of C will be needed. Both resistors can be variable producing any slope desired. L adjusts turnover frequency together with the mic output impedance. Same for C. So 2 parametric filters can be made inside the head amp.


If a directional microphone such as ribbon, or moving coil unidirectional is connected the following addition filter may be needed. An inductor in parallel again with pins 2,3. It's value will depend on the mic, the type of singing, the mic impedance and how close the distance of mic to source. Different again switchable values may be used and the process may be paralleled with the focusing adjustment on camera, macro settings for example.


All these Pleiades filters do not normally interfier with the quality of the mic's signal. The microphone is always connected to pins 2,3 ie straight to the head amp input. The passive Pleiades filters just remove what is not needed ie are subtractive.


Switches can be arranged such that anything can be in or out.


No make up gain may be needed as all these passive filters do is remove what is not sanded to aproach ideal of flat frequency response from producer's brain to listener's brain [Lowe, Morgan]. An ultra low noise head amp such as the Pleiades V6 may only make things better.


The Pleiadss filters can also be external to the head amp. For example they may be implemented inside XLR female to male barrels. Neutrik modules cylindrical or larger rectangular ones are recommended as they are functionally and aesthetically perfect.


D


Reference:


Flat frequency response from singers vocal chords to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE

Why even a very small voltage can be dangerous

Power is V x I, voltage times current.


Ohm's law is I=V/R


If the load is too small and for example a battery has a small internal resistance (ie not too much drop across its terminals) the current flow can be huge.


When experimenting with circuits powered even by a 1.2V battery a fuse such always be in series with the battery for safety.


For many reasons metallic (electrical conductive) jewelry should not be worn. A short circuit can result in excessive temperature rise.

Ways of powering the Pleiades V6 Nuvistor

At your own risk. Attention when using batteries. A series specially selected fuse should always be used for safety. Batteries, especially Li-ion have strict charging requirements for safety. All safety precautions must be exercised.


There are great li-ion chargers on the market. One that has been tried with impressive results is the Fujicell.


Your own risk.


Below are at least a few options.


The Pleiadss V6 head amplifier circuit is the following, Cc can be 22nF, the electron tube can be a Nuvistor 7586 too. The Pleiades bias resistor can be 6MΩ. different interesting sound quality can be adjusted by varying this resistor. If should not normally be below 2MΩ.





Solar powered.


3 AA rechargeable or fixed batteries.


One li-ion 3.7V battery. A high capacity battery should give at least half day of continued operation.


One 4V lead acid battery. (Just found out today that 4V or 8V lead acid batteries exist).


Hand crank option. Just joking. But it may power a battery charger.


A great manufacturer of battery holders is Bulgin.

The power consumption of Pleiades V6 Nuvistor

Using the RCA 7586 Nuvistor electron tube. A usual value of Pleiades bias resistor for EF183 or 7586 is 6MΩ, Cc to grid is usually 22nF.





The current consumption is 100mA for heaters and 25μA for anode.


The voltage supply is 3.9V.


So power consumption is 3.9V x 100mA = 390mW


Pleiades schematics or concepts are open source.

Hello to France and to Hungary

An electron tube becomes a source of voltage when cathode is heated

We can get this voltage between grid and cathode for example. The grid is negative.


See the previous euroelectron post.

Pleiades bias operation

(There is another euroelectron post called The Pleiades Bias.)


Even when nothing else is connected to an electron tube but heater voltage, the electron tube becomes a source of EMF (voltage) between cathode and grid.


A typical value can be -700mV, ie the grid being negative wrt cathode. A possible cause is the cathode becoming positive by emmited electrons.


The above is very easy to verify possibly for any tube. (A series fuse to heaters should always be used for safety). Any voltmeter should be suitable even one of not very high input impedance.


Curves of voltage vs current can be seen on Techniques for application of electron tubes in military equipment. The more current we try to get out of this source the less the voltage becomes, like any battery with internal resistance. The graphs show a straight line indicating a certain magnitude of internal impedance, the slope itself.


One can use the Thevenin theorem and obtain the magnitude of this internal resistance by deviding the open circuit voltage with the short circuit current [Neil Storey]. The short circuit current. It is obtained by directly connecting a micro ammeter between cathode and grid.


A typical value of internal resistance might be 20KΩ !


So when we try to operate the electron tube with a few volts at the anode it is not possibly as the grid is already at a cutoff value for such low anode voltage.



By applying Pleiades bias the grid potential is lifted up closer to 0V. A typical new equiplbium value of grid voltage can be -50mV with respect to cathode. The electron tube can now operate normally at only 3V anode voltage. Ultra low noise circuits as possible.


Below is the schematic of Pleiades V6 using a Pleiades bias resistor of typically 6MΩ from anode to grid. The 7586 Nuvistor electron tube may also be used. Another electron tube with great sound so far at low anode voltage using this principle is the 12AU7 or ECC82, see Pleiades V0, V3 amplifier.





Further reading on the classic Armstrong (inventor of FM) paper.


References:


Techniques for Application of Electron Tubes in Military Equipment - Rex Whitlock - page 1-11
http://www.dtic.mil/dtic/tr/fulltext/u2/142061.pdf


Electronics, a systems approach - Neil Storey


Operating Features of the Audion - E. H. Armstrong

Very soon euroelectron pagesviews will be 45,000

Thank you !

Hello to Netherlands

Sennheiser MD21 HN to Pleiadss L,R filter to Pleiadss V6 Nuvistor

This is the schematic of the head amp used with the difference that Cc is 22nF as usual, Pleiades bias resistor is usually 6MΩ when an EF183 or Nuvistor 7586 electron tube is used. A Nunvistor 7586 was connected and its heater was connected directly to 3.9V. (No series droping resistor). 3 AA rechargeable 1.2V Sanyo Eneloop batteries are used. A series fuse should always be used for safety.





Signal path, setup:


Male singing voice - Sennhsiser MD21 HN at 1-2in - (Pleiades L,R filter) - Pleiades V6 Nuvistor in breadboard with Altec 4722 input transformer and Pleiades 10:1 output transformer (see relevant post) - Sony TC-D5 Pro XLR mic in mono mode - Sennheiser HD580 warn by singer as usual



In the beginning no mic was connected, then the heater voltage was applied to Pleiades V6. After a while some hiss could be heard from the open input Pleiades V6 through the headphones. It happened to be raining. Then the mic was connected and so much sound and detail came out of it, it was scary. The MD21 can act as a vacuum cleaner sucking sound from everywhere. Very impressive. The Nuvistor giving a very big sound with almost no noise.


The sound was bass heavy for intimate vocals due to Fletcher - Munson, voice effort curves etc.


Then the Pleiades (130Ω,40mH) serial number 18062416, see relevant post, which was supposed to be 140Ω,40mH was connected between mic and Pleiades V6 input. Immediately the sound was balanced.


Then the experimental Pleiadss 145Ω,42mH was connected (this is made up with cable clips etc). It sounded great too. Less midrange than the (130Ω,40mH). So the 130Ω sounded more clear, the 145Ω more full bodied.


It may be a good thing that the 130Ω,40mH Neutrik module Pleiades filter has not been changed to 145mH as it sounds more suitable for the MD21 HN than for the MD211 N.


References:


Flat frequency response from producer's to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE


The Pleiades 140Ω,40mH microphone filter - euroelectron
http://euroelectron.blogspot.com/2018/06/the-pleiades-14040mh-microphone-filter.html

Hello to France, Hellas, Italy, United States

Op amps should be great for instrumentation

Not musical instruments.


See the next post with reference the Russel O. Hamm JAES tubes vs transistors (vs op amps) paper.

Another argument in favor of 1 speaker reproduction

On one of the beloved Book of Experiments - Leonard De Vries one experiment title is clearly Sound + Sound = Silence


It refers to what happens when waves meet out of phase. One wave tries to move molecules to one direction. The other wave tries to move the air molecules to the other direction.


When 2 loudspeakers are playing in the same room statistically for every frequency there should be equal number of points in space where waves meet in phase or out of phase.


This is possibly the reason why we might be asked to sit exactly between the 2 stereo speakers. Unrealistic or unnatural siting position. The only naturalness about it is a woman sitting on top of a man or the other way round when both want to be in the middle. And then again you can't be inside the other person's head.


Most of these posts are written while listening to a single Pleiades 2N3053 - Philips AD5046N. This is possibly the best argument. The sound quality.


Is a single speaker the reason why some Juke Boxes or radios sound so realistic apart from the fact they use electron tubes? By the way transistors can sound great too if they are treated like electron tubes on similar schematic simplicity. One reason is no feedback, relatively high output impedance ie semi constant current source conditions. And of course the fabulous gentle overload characteristics of
class A amplifiers. And distortion tending to 0 as the signal tends to 0.


Operation in class A means electrons flowing all the time.


Bibliography:


Tubes vs Transistors (vs op amps), is there an audible difference? Russel O. Hamm - JAES

Hello to the United States of America

Why having 2 speakers when you can have 1?

Possibly the closest to (viral?) virtual reality.


Single point source as in real life.


References:


Pleiades 2N3053 - Philips AD5046N


Phil Spector Interviews


Joe Meek interviews

Antiwise winding of Pleiades LR mic filters

If the same inductance is needed with more R some turns can be wound anti wise.


This will give a still gentler low cut or high pass slope.


See next post.

Making still easier Pleiades LR microphone filters

With for example the input transformer is made on a ring core...


Then it is easy to just add a few turns making a very low impedance winding.


Then a Pleiades filter can be connecte to this winding to compensate for Fletcher - Munson, voice effort curves.


The turns needed for the Pleiades LR filter would accordingly be very low.


If a very thin wire is used it may be easier to create a higher resistance to inductance ratio. Hence a gentler low cut slope without the need of an external resistor. So the R element will be inside the inductor itself. If more R is needed then some turns can be made anti wise from the normal methods of winding.


The objective is flat frequency response from producer's brain to listener's brain, see reference.


Reference:


Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan

Hello to France and Poland

Playing with an online tone generator while a song is playing

An interesting psychophysics experiment.


Not easy, not difficult. (Take care to have acoustic levels low for reasons. Protecting your hearing and the fact that pitch depends not only in frequency but on intensity too.)


A nice classic song can be playing softly.


Then using an online tone generator such as:
http://onlinetonegenerator.com


Then finding a note that suits the whole song. Playing such a note at high frequency by changing the input frequency in the keyboard until it sounds perfect to ear brain.


It may not be believed how equal temperament is out of real life.


Trust your brain.


Bibliography, references:


Ear brain vs Engineering octaves - euroelectron


http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html


Sound and Hearing - Stevens, Warshopsky - Chaoter: Influence of the mind - Life science series

Dreaming of connecting a Jensen transformer on the Pleiades V6?

It was realized half awake half asleep that a Nuvistor electron tube would also work at 4V.


It looks very obvious but this idea had never come when fully awake.


Same last night-morning. The idea of using a conventional high quality transformer such as Jensen hardwired came.


A 1:10 Jensen JT-115K-E is available so why not. In the datasheet they claim to be the Worlds finest audio transformers. This is a bold statement. They should know. They also have a very helpful explanation on their website of the pin 1 problem. The connection of pin 1 in the schematic below comes from their passing of knowlege. Pin 1 is just connected to the left terminal on the Neutrik socket. So effectively pin 1 is connected to the metal enclosure.


Also trying to make life easier, an old box with electron tube socket and Neutrik XLR input and output sockets is already available. It was from an old (pre 2000?) experiment including an interstage transformer and a double triode. It never quite worked at 12V. Pleiades bias was possibly not known at the time. With Pleiades bias it is very easy for an electron tube to operate beautifully with possibly lowest noise at even 4 volts for both heaters and anode. On the Pleiades V6 schematic below the transformer secondary grid coupling capacitor is usually 22nF. The Pleiades bias resistor is usually 6MΩ. it works well with the Nuvistor 7586 electron tube too. Maybe it's time to hard wire including the transformers without octal bases.






References:


The Pleiades Bias - euroelectron


Operating Features of the Audion - E.  H.  Armstrong

The 2 frequencies used while measuring inductance

The Escort ELC-120 LCR digital meter is used on all these Pleiades experiments. (Electrolytic capacitors should really be replaced as they are old).


When the scale is switched to 20H it sends a much lower frequency signal to its terminals.


Today the 2 frequencies it uses were measured by beat comparison with the online tone generator. The Sennheiser HD580 headphones were connected to the Escort meter (careful with acoustic levels for protecting ears). The tone generator was playing on the iPad's speakers.


This is the tone generator used:
http://onlinetonegenerator.com


The 2 frequencies are 1028Hz and 97Hz, + or - 1Hz.


Some inductors have a much higher value of inductance at a lower frequency. It depends on the material of the core. Mumetal for example.


The Jensen JT-115K-E was measured:


Both measurements at 97Hz.


Primary inductance: 7H


Secondary inductance: 665H


There is some uncertainty on the 665H measurements as the instrument may already be out of its range.

A 30mW one transistor amplifier is loud

A visitor commented today on how nice does it sound.


When a louder track came up she asked if the volume could be turned down so that it would not interfere with conversation.


The volume could not be turned down as the series potentiometer used at this time was already fully counterclockwise. So it was turned off.


(R, L chanels are connected together at the CD player line output, reproduction is through 1 only speaker and it sounds with great definition and clarity as expected since it is a point source).

It is amazing thinking that the power consumption is only 8mA at 12V. Pure class A (electrons flowing all the time). And any battery lasts for so long.


Signal path, setup:


The Classic Collection CD - Sony portable CD at line out (L+R) - Pleiades 2N3053 - Philips AD5046N - half tiled kitchen with high ceiling

Hello to Hellas, Germany and Ukraine

Commercial fruits should be characterized by the date they were cut?

Not when packaged.

An approach to compensating the proximity effect

Firstly using a good quality omnidirectional microphone. Connecting to it the right inductor in series with resistor (Pleiades RL filter) until flat frequency response from producer's brain to listener's brain is approached. (Even a flat omni mic may sound bass heavy due to equal loudness curves and voice effort curves.


Then using a directional mic of the same impedance connected to said Pleiades RL filter.


Then adjusting mouth mic distance or inserting a further parallel inductor (Pleiades L filter) for given distance until the result is flat from producer's brain to listener's brain.


Will it work?


Bibliography:


Flat frequency response from singer's vocal chords to listener's brain, Sound Picture Recording and Reprocucing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE

Changing multimeter cable

The YFE multimeter cable was replaced with a good quality new silicone one.


It is the first time that the digital meter shows exactly 0.0 Ω when the 2 cables are connected together.

The hiss sound when connecting dynamic or ribbon microphones is coming from the preamplifier?

Very possibly so.


It is not from the microphone.


Some moving coil microphones for examole have equivalent acoustic noise figures that are extremely low.


When moving coil or ribbon microphones are connected to the Pleiades V6 head amplifier they sound at least as big, sensitive or low noise as the best condenser microphones. And of course with no s problems while the high frequency end sounds very extended and very natural (moving coil microphones do not have HF diaphragm reasonance. For example using Electro-Voice RE15, Sennheiser MD211 N, Grampian DP4/L etc.




(Coupling capacitor is usually 22nF, Pleiades bias resistor 6MΩ, the Nuvistor 7586 electron tube can also be used)


By feeding the follwing preamplifier with a hot signal of high s/n its gain can be reduced and the amplifier hiss decreases.

Does Pleiades bias reduce the influence of various sources of grid current on electron tube noise?

It is early to say.


This is a hypothesis. The grid to anode external Pleiades bias resistor removes many of the electrons that may cause grid noise out of the electron tube, out of the cathode grid circuit. They go externally directly to the anode. (The Pleiades bias resistor can also be connected to Vb or any other positive potential source).



Pleiades V6 schematic, Cc=22nF, Pleiadss Bias Rag=6MΩ, Nuvistor 7586 electron tube can substitute EF183


On Techniques and Applications of Electron Tubes in Military Ewuipment, page 1-14, at least 4 sources of grid current are identified.


a. Electrons of high initial velocity. (This seems to be what is described in previous euroelectron posts as what happens when just heater voltage is applied to an electron tube. Electrons emmited from cathode leave it positive or make the grid negative. By closing an external circuit between cathode and grid electrons are transported out of the grid and back to cathode. Pleiades bias externally couteracts this internal bias mechanism so that the electron tube can operates with a very low plate or anode voltage.)


b. Ions formed by collisions.


c. Interelemnt conductive paths (surface leakage).


d. Undesired electron emission (from elements other than the cathode).


The hypothesis is that the Pleiades resistor takes many of these electrons out of the electron tube and away from the cathode grid circuit.


Furthermore since the electron tube can now operate at very low anode voltage, the heater voltage can be reduced too for same space charge conditions [Pearson], [Llewellyn]. A low cathode temperature makes the other electrodes less hot too thereby minimising some of the above effects.


Space charge conditions may make this external grid to anode current be free of shot noise.


So far the experimental evidence that the Pleiades V6 is a very low noise circuit is listening microphone tests comparing with other electron tube or JFET, bipolar preamplifiers. Some of them of the highest quality.


The fact that even a very low output Grampian ribbon microphone can sound very big and of a high s/n.


Also the fact that short circuiting from ground or cathode to the input coupling capacitor makes the noise at the output almost disappear in a dramatic way.


More experiments are needed and of course building the Pleiades V6 hardwired.


The increase of input resistance test can be done then until the value of output noise is double the short circuit noise. This would give the equivalent noise resistance. [Pearson]


References:


Techniques for application of electron tubes in military equipment - WADC TR 55-1
http://www.dtic.mil/dtic/tr/fulltext/u2/142061.pdf


Fluctuation Noise in Vacuum Tubes - G. L. Pearson - (can be found on archive.org)


A study of Noise in Vacuum Tubes and Attached Circuits - F. B. llewellyn

Making Pleiades filters with 2 different material cores operating simultaniously

For example a ferrite indictor in parallel with a nanoperm inductor.


Or placing 2 different ring cores  on top of each other and winding the wire through both.


Perhaps the equivalent of using laminations of different materials to exploit the different change of inductance (magnetic permeability?) with respect to frequency of both materials or other properties.

Why the Pleiades filter 70ohm,40mH,70ohm does not sound as good as expected?

The experimental mic filter with wires sticking out all over the place, crocodile cable clips, sounds more big and natural.


Why?


because there are 2 different cores operating at the same time?


the bad contact good sound syndrome?


not known yet, more experiments are needed.


The first obvious thing to be done is measuring resistance. This is measured by the Escort LRC meter which can measure R at some frequency. (DC is not recommended as it can magnetism the core).


There was difference in R between pin 2 and pin 3 on the 2 Pleiades filters.


The experimental one measured 144Ω while the hardwired one only 130Ω.


By measuring inductance between pins 2,3 the experimental measured 42.4mH while the hardwired 41.9mH.


Obviously there is change of low cut or high pass slope slope because of the different series R. Both will be less than 6dB per octave but the experimental one is even less abrupt.

Pleiades serial numbers are date time codes

For example the first Pleiades RL (Flecher-Munson, voice effort) compensation microphone filter just made inside Neutrik XLR cylindrical modules has the serial number:


18062416


18 is 2018
06 is June
24 is day
16 is time


This should be very similar to military date time code.


Used for serial numbers it has the advantage of uniqueness of number and that a later creation always has a greater number.

The Pleiades (140Ω,40mH) microphone filter is ready

Serial number (date time code) is 18062416.


It reduces bass at a slope smaller than 6dB per octave in an attempt to compensate for Fletcher Munson, voice effort curves with the minimum number of components, simplest signal path. The attempt is really flat frequency response from producer's brain to listener's brain. Some nice sounding and natural L, R values with no bass heaviness were found by singing to the magnificent Sennheiser MD211 N connected to the Pleiadss V6 one electron tube head amplifier. The input transformer used in the Pleiades V6 for these experiments is the Altec 4722. See relevant posts.


The values of 40mH and 140Ω were chosen.


The resistor is in series with the inductor. The total is connected in parallel to the voice coil (or amplifier input).


In order to make it completely symmetrical it was made as 70Ω 40mH 70mH.


A total of twenty 680Ω very small carbon resistors were measured until 2 were found with the values of 70Ω. So 2 matched 70Ω resistor were used.


Neutrik cylindrical XLR modules were used so that the end result is beautiful and of great quality. The centre stripe gap was filled with blue nail paint-varnish. (Annie Paris no 245). The stripe is made as best as possible by protecting the hills that are not to be pained by scotch opaque tape. The tapes are removed as soon as possible after applying the paint.


So it looks like a very beautiful Neutrik XLR female to male adaptor with a blue centre stripe.


How is it made?


The schematic is as follows:


Starting from input, pin 2 is connected to one side of 70Ω the other side to 40mH, the other side of 40mH to the other 70Ω resistor and the other side of this resistor to pin 3. At the same time a twisted pair thin single core cable connects pin 2 of input XLR to pin 2 of output XLR. Same for pins 3. So the mic signal goes straight through. It is only the nasty bass that we do not want that the filter removes being a subtractive passive filter.


No make up gain is needed. For a great signal to noise ratio a Pleiades V6 mic booster electron tube head amp can be used after the mic and filter. The output will be a healthy strong signal. The following preamp can be set at low gain so that it's hiss is reduced.


Pin 1 ie Xternal is connected to the metal part of the Neutrik connectors following the great advice from the Jensen transformers website, as we would do when building a preamp with XLR connector sockets to avoid pin 1 problems.


Opaque thermal sleeves are rolled inside the resistors and used to protect from short circuits of their end terminals.


So far the Pleiades mic filter has been tested will an inductance meter. Although the resistors are in the circuit, the meter still shows 40mH.


(Later same day addition)


How does it sound.


Unfortunately it sounds nice but as good as the experimental on with wires sticking out all over the place.


The one with 2 different inductors in parallel and 1 resistor all vonnected with aligator cable clips sound more bandwidth extended, less peaky etc. 2 different cores are used one Siemens ferrite and the other Magnetec Nanoperm.


Later on an obvious difference measured is higher series resistance on the experimental Pleiades filter. More on a latter post with title Why the Pleiades filter 70ohm,40mH,70ohm does not sound as good as expected?





References:


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE


Pleiades V6 schematic (with 22nF, 6MΩ Pleiades bias resistor, EF183 or Nuvistor 7586)

A Mix app?

This may require a lot of memory but not perhaps if all the files are elsewhere.


Does such an app exist where the user can mix a well known song?


For example having access to the levels of all tracks of Breathe - Pink Floyd.


It may be a very good way to understand how music works. By being able to listen very clearly to each component voice (part) or instrument and what it does to the whole, harmony, bass and rhythm. For example realized there may be 2 faders with Dave singing the same part, (double tracking) giving a nice rich phasing harmonic result.


The mix app. (Mixup)

Hello to France and Poland

More euroelectron page views this week than usual from Sweeden

Thank you !

A method to gently low cut the Sennheiser MD21 HL

At your own risk.


The Sennheiser MD21 HN is one of the best microphones on the planet.


For a not loud singing voice and loud acoustic reproduction it can sound bass heavy to our brain due to Fletcher-Munson, voice effort curves.


One way to get flat frequency response from producer's brain to listener's brain is their following:


We exploit the fact that there's is an internal transformer stepping up the voltage. So we may connect the hiZ out to a JFET or electron tube. So we have a world class signal to noise ratio. See Pleiades K117, Pleiades V4, V6 etc.


We may then use the low Z output of the transformer for filtering the excess ear brain bass. For example an LR (L in series with R) Pleiades filter can be connected, (see previous posts). So without doing any modification to the microphone a 3 conductor and screen cable can be used and everything can be implemented on the other side. We may use the fact that star quad cables have 4 conductors if we cannot find a high quality 3 conductor cable.


If we use a Pleiades K117 JFET head amp it can be powered by the mic in of devices for electret mics. Or we can use an AA battery power supply inside those plastic barrel box adapters etc. Then we may feed a world class Sony TC-D5 M, Maractz PMD430 or Uher 4200 possibly obtaining an amazing signal to noise ratio and flat frequency response from producer's to listener's brain. It might be possible to use the input resistor of a Marantz PMD430 or CP430 etc as the load resistor, further reducing the number of components, see relevant Marantz post. Or a Nuvistor 7586 electron tube can be connected to the hiZ MD21 through a capacitor to control grid. use Pleiades bias and all we need to do then is power the heaters and anode with about 4 volts. ;The anode resistor may be the device in out resistor). See previous Pleiades V6 Nuvistor posts. A fuse should always be used is series with a battery for safety. See relevant post.


Of course we may also make an XLR female to male adaptor and include inside the Pleiades LR filter (see previous posts) and then feed a balanced mic in low Z input. Even with only 82mH in parallel the MD21 can sound brilliant, but it is best to include a series resistor to the inductor to control the slope. Signal to noise will depend on the front end amplifier. An ultra low noise front end is the Pleiades V6 electron tube head amp. Recently 22nF is used and a Pleiadss biasing anode to grid resistor of 6MΩ.





Bibliography:


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE

The Bach successors

With a few exemptions...


The successors of Corelli, Vivaldi, Bach, Motzart, Medelson, Rachmaninov are:


Rodrigo, Jobim, Procol Harum, Pink Floyd, Madonna etc.


These artists or their producers use the same harmony or code proven for centuries to sound correct and pleasing to the human ear or brain. Only the instruments change or the production techniques.


the book that describes this code has only be read by so few or understood by so few while listening [Neidt, Bach].


Example: To Have and not to Hold - Madonna


Reference:


The Neidt, Bach manual, (instructions for playing though bass or 4 part harmony made by Johann Sebastian Bach for his scholars in music)
Bass Bass Rules PDF: (ear brain rules)
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf

Pleiades filters should look very nice too

They should not only sound correct to ear brain they would look nice too.


A Pleiades LR (gentle slope low cut) filter is being prepared to be used with Senheiser MD211 and other world class microphones.


It is made with Neutrik XLR cylindrical modules. The central module stripe is painted blue with nail color varnish.


The magnetic core is a toroidal Siemens Epcos wound at 40mH. 2 sirens resistors of 70Ω will make a total of 140Ω series resistance.


It would be RLR. And the ends of the resistors connected to signal or pins 2,3.

A UV frequency is 1000THz

(At your own risk, this is not a medical advice, take all safety precautions).


(10 to the power of 16) Hz. This is electrons going up and down at a frequency of 1000THz or at thousand million million times per second.


Is this why we feel so happy when we are our early in the morning? Or near sunset? Or being on the beach or swimming to the sea at such hours? The sky is violet at that time.

Songs with each choir note on a different fader

Playing the console is much different to playing the keyboard. There are delays and crossfades while hands are playing the faders. (Very interesting harmony or code is created as we may not be realising what we are playing). And it sounds ethereal.


Examples:


Souvenir - OMD
https://m.youtube.com/watch?v=XDIYOiQUi2s#fauxfullscreen


I'm not in love - 10cc
https://m.youtube.com/watch?v=OtBHfxU2wmc


References:


OMD documentary
https://m.youtube.com/watch?v=LyYaWD3DWIU#fauxfullscreen
At 1:08:50


Good Vibrations - Mark Cunningham

Hello to the United States of America

A great example of pedal bass, Ab

OMD documentary - YouTube
https://m.youtube.com/watch?v=LyYaWD3DWIU#fauxfullscreen
After 38:00


It was supposed  to be G but the transpose was on by chance. The Ab key gives a very distinct atmosphere as most black keys or scales do.

The OMD sounds

OMD Documentaey - YouTube
https://m.youtube.com/watch?v=LyYaWD3DWIU#fauxfullscreen


Very interesting, for example after 24:00, how Electricity - OMD was made...


A great example of pedal bass, from 38:00


53:00 Enola Gay and unisons, (many synths playing the same notes).


At 1:08:50
Souvenir

Hello to Argentina, to Denmark and Canada

Preparing a Pleiadss LR filter for MD211

It is getting too scientific.


A Siemens Epcos ferrite powder core of similar size as the Magnetec nanoperm 073 was picked up. And an enameled wire of 0.2mm was chosen by chance or first glance.


According to previous experiments a 40mH inductance is aimed for. And then a series resistor of 140Ω will be connected (or 2 of around 70Ω on each side). Then the total will be connected to pins 2 and 3 of a Neutrik XLR female to male adapter. The objective is to compensate not for the proximity effect (omnis do not exhibit the proximity) but for other effects, Fletcher Munson curves, voice effort curves so that the result does not sound bass heavy to the listener's brain [Lowe, Morgan]. The bass heaviness is very easy to verify by singing at not a loud voice and monitoring with reference headphones. The Sennheiser MD211 N is understandably one of the best microphones on the planet and will be used in these experiments connected to the Pleiades V6 electron tube battery powered head amp. See previous posts. The MD211 has possibly complete absence of s problems.


Before winding the 0.2mm wire to a wooden a few inch long thin wooden stick (this helps to wind all the length of wire to the ring core) it was realized that the stick was already wound with a very thin wire from a previous winding experiment. It was too thin to be seen. It can be a very good wire for introducing the required resistance.


But due to haste the 0.2mm was wound on a different wooded stick and the core was already under way. So perhaps the too thin wire will be wound at some other time.


Filling all the space at one layer (100 turns) gave 20mH. Too low perhaps for this experiment but who knows?


Fortunately in the same core drawer was found the same type of core wound with 0.16mm red colored enameled wire. It turned out that it's inductance is 40mH! So again when we rush it takes more time.


So all is set. Or Rather was already set. The 20mH may be used at a different experiment. Τιποτα δεν παει χαμένο.


Neutrik modules will be used to assemble the XLR barrel Pleides LR filter.


Bibliography:


Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - JSMPE

Hello to Australia and United Kingdom

The importance of contact cleanliness of 200Ω mic circuits

On minimum number of component systems every detail can make much difference.


If the signal levels involved are low and the microphone head amplifier is ultra low noise, analytical a change in input circuit resistance will manifest as increase in thermal noise or hiss.


Such is the case for example with the Pleiades V6 battery powered electron tube head amplifier. If cables are reinserted to the breadboard a small hiss can be heard to decrease.


A small problem in any contact including batteries can be heard as a very loud noise.


At the moment it is in breadboard stage and a problem in the 200 Ω input cabling will increase thermal noise or hiss.


Microphone plug and socket contacts should kept very clean. The Pleiades V6 should be built in a hard wired experiment box even perhaps before moving to the octagon Hammond orange aluminum die cast box.


Should barrier strip be used for the mic input terminals having resistance tending to 0Ω or a clean Neutrik XLR?


On noisy amplifiers these effects many not be heard as they are covered by the noise.


Would the Pleiades V6 sound even less noise when hard wired? Either Nuvistor 7586 or EF183 will be used. See previous posts.

Star quad cable

It seems a brilliant idea.


A shop where the Mogami W2893 mini quad cable can be found is the nice PA solutions shop in Athens.


By looking at the crossection of the cable we see 4 cables in a cross crossection.


The upper and lower part of the cross are to be joined together forming for example live.


The left and right part of the cross are to be joined together making for example return.


Are star quad cables made by twisting all 4 cables together? It may be tried, twisting 4 cables produces twisted pairs. And the total crossection is a cross which is much closer to a circle.


How would this cable sound with Sennheiser MD211 driving Pleiades V6?

The Pleiades 2N3053 to Sennheiser Hd580 powered by 3 volts

It was first tried with 1.5V (in fact 1.3V) and sounds brilliant with a very extended bandwidth.


The so beautiful Don't you Forget About Me - Simple Minds 80's song was on the portable Sony CD player.


The Sennheiser HD580 have just had their ear pads replaced by genuine parts and sound like new.


The HD580 were first connected directly to the Sony CD player. The sound was very nice.


Then through Pleiadss 2N3053 at 1.3V. Bandwidth ear-brain perception was extended. There was some euphonic harming perhaps enhancement. The sound was loud.


Then 2 AA 1.2V batteries were connected in series. The sound was louder and perhaps clearer. But in the end the 1.2V was prefered. At 2.6V it was starting getting too loud. Bias was not readjusted. It may have to be done to optimize for 2.6V operation.


With such conditions the 1.2V sound was relaxed, easy and big.


It has to be considered that as DC current increases since it passes through the headphones (no capacitor) the reasonant frequency of the headphones may change because of a change in tension.


As some grain was observed, so an older CD from Columbia was played too. Ray Conniff. It sounded brilliant.

How CD may gets away with it

If a CD is listened in a room with a loudspeaker the reverberation of the room seems to cover some of the grain nastiness.


Listening with a very analytical headphone setup as the one transistor per channel Pleiades 2N3053 to Sennheiser HD580 the sand grain can be heard. Also at small modulation levels if the amplifier is increased noise is very easy to hear. This would be 0 1 random noise. Sand.


At digital systems distortion tends to infinity as the signal tends to 0.


On analog class A (electrons flowing all the time) distortion tends to 0 as signal tends to zero just like nature.


And analog hiss (thermal agitation of electrons) sounds so nice.

Replacing genuine only Sennheiser HD580 earphones pads

This time spares were bought from Nakas shop in Athens, the authorized distributor and not from online.


They felt different. The thin foam layers that are inserted before inserting the pads were much larger covering the whole area. So much more force was required to fit the pads in place.


But the sound is amazing. The headphones sound like new.


Before inserting the pads dust was blown carefully away by a (usually used for piano mechanism dust  removal so was bought form piano parts supplies) hand air blow pump. It is tricky as the membranes can move up nand down as air in blown. But by looking with a magnifying glass there was much dust to be blown away. And this must have happened because of the smaller circumference thin fabric that was supplied last time.


The price tuned out to be as much as the online. No shipping.

How to connect an electron tube to iPad or other electret mic in device

At your own risk.


This is to be used with a Pleiadss low voltage supply amplifier. A battery should always be connected in series with a fuse for safety.


On how such mic amplification may be done see the next euroelectron post.

Can the anode voltage be supplied by the iPad or other device headphone connector

Your own risk, use all safety precautions.


The iPad 1/8in headphone-mic connector sends a small voltage through a load resistor which is inside it. Is it 1.8V?


It is a very small voltage normaly used to power a JFET.


Would it power a Nuvistor 7586 electron tube anode or an EF183 or a 2DS4 Nuvistor etc?


If the Pleiades V6 mic booster amplifier is used with Pleiades bias it may be possible.


The Pleiades or anode grid bias resistor may have to be reduced.


In it works it may be nice as the load resistor and capacitor would be inside the device.


All then needed to do is supply the electron tube with a heater voltage. It can be redused as the space charge condition is achieved at lower temperature the lower the anode voltage is. See previous posts and referenced papers on fluctuation noise in vacuum tubes.


So a 7586 or EF183 would need a 3.8 heater battery. A 2DS4 should be fine with an 1.2V C type battery for example. (A fuse should always be used in series with a battery for safety).






Above is the schematic where both heater and anode voltage is supplied by the same battery. In order to connect this to an iPad a Pleiades K117 JFET amplifier can be connected and it will be powered by the iPad in the same way.

So the first option if it works may be simpler as no output transformer is needed, no extra anode resistor or output coupling capacitor.

Hello to France and Polland

The best enema?

This not a medical advice.


Neither is it a serious post.


It was discovered by chance after eating an apparently bad quality piroshki supposedly oven baked but who knows what was the oil it was brushed with before it entered the oven. And who knows what was the quality of the white cheese used.


After a few hours output from the body may become so liquid and visisting the toilet it may feel as such. Is it effective?


Repeating again this post is not a medical advice one may make a great, healthy, tasty meal. The Pleiades (oat flake, sesame, raisin,...) meal based on Muesli, see previous posts, is such an attempt.

Playing with electrons

At your own risk. All safety precautions should be exercised.


Even when using a small battery it is very important that a fuse is connected in series.





See earlier post.


Of course another way to play with electrons is the one transistor Pleiades 2N3053 amplifier driving a loudspeaker. See previous posts.

Listening to the sound of electrons and positive ions

At your own risk. All safety precautions should be exercised including fuse in series with battery and using low acoustic levels, limiters etc to protect the ears.


Even earlier that 1930 where electron tubes were as popular as they are today the limit of amplification was reached or explained.


Many electron tube amplifiers would be connected one feeding the other until the thermal noise of electrons was clearly heard as hiss.


Much larger ions when they are attracted near the cathode grid space change have a different sound quality especially when the effect is prominent by an increased cathode temperature [Pearson].


Inside an electron vacuum tube we have a great lab to study electrons, ions and their effects.


The Pleiades V6 microphone booster electron tube amplifier is a low noise attempt to play with electrons or amplify the smallest signal without the need of high voltage and bulky power supply. You act at your own risk and all safety precautions should be exercised including a fuse in series with any battery.





Normally the Pleiades bias (anode to grid) resistor is 6MΩ. The coupling capacitor is usually 22nF. The Nuvistor 7586 can be used. The ECC82 also etc. Sound quality or anode current, input impedance can adjusted by the Pleiades bias resistor.


It is based on possibly 2 of the best low level amplifiers on our planet for microphones. The Neumann U47, VF14 amplifier and the RCA BA-2C booster amplifier. Note the cathode temperature of the VF14 electron tube is reduced by a lower heater voltage than specified by a datasheet of VF14.

References:


Neumann U47 schematic, can be downloaded from the BBC link below:
https://www.bbc.co.uk/rd/publications/rdreport_1954_23


RCA booster microphone BA-2C amplifier
http://www.coutant.org/ba2c/

Is the Pleiades bias anode grid current space charge limited?

If this external current [Pleiadss V6 schematic] is then it may be good news meaning that it produces no shot noise [Pearson]. Space charge or (charge sea) make shot noise tending to zero as there is not descrete emission of electrons. The sea of electrons is already there.


At the same time Pleiades or anode to grid bias increases anode current, decreases internal plate resistance, increases transconductance. (Therefore thermal anode internal impedance noise. The input impedance is also reduced. Measurements according to the classic paper of Pearson should be made.)


The electron tube can be powered by just a few, typical 3V, at the anode.


The heater voltage therefore can be reduced as the cathode temperature can be lower for a space charge saturation effect.


Secondary emission is reduced, positive ions too and therefore most sources of electron tube noise should be eliminated or greatly reduced.


More measurements are needed according to this classic paper that says so much. [Pearson]


Back to the 1930's where electron tubes were as popular as today there was so many fantastic research and papers written by the pioneers of electronic engineering or control of electron flow engineering or art. For a formal definition of electronics [Gray]





References:


Fluctuation Noise in Vacuum Tubes - G. L. Pearson
https://archive.org/details/bstj13-4-634


Applied Electronics - T. S. Gray - MIT

The pedal bass, unison tricks of Enola Gay - OMD

This 80's songs sounds are fresh and dynamic as ever reproduced on the Pleiades 2N3053 - Philips AD5046N reproduction system.


OMD very few months after their school mates critisised badly their abilities were being heard through Enola Gay and Electricity in many European countries.


Pedal bass is used in a generalized sense. It is the melody riff Fa Re Fa Mi Fa Re Fa Mi Fa ... which is kept unchanged, constant while bass and harmony is changing. So together with the pedal bass (melody) all sorts of interesting intervals or code from bass to melody is being created. Listen also to how nice a double tracking is done to this riff, one on the left channel,the other to the right channel.


Also great unisons can be heard as apparently the same note in a melody is being played by many synths simultaneously.


Very interesting documentaries of OMD and the making of these songs can be found on YouTube.


For example at 53:00 we can hear many synths playing the same notes (unisons) of Enola Gay.
OMD Documentary - YouTube
https://m.youtube.com/watch?v=LyYaWD3DWIU#fauxfullscreen

Hello to United States, Australia, Germany, Hellas

Το βιβλίο που μπορει να βγάλει την Ελλαδα απο την κριση

Εγχειρίδιο - Επικτητος.


Μπραβο που εχει αρχίσει να διδάσκεται στο σχολείο.


Επισεις για άσους ασχολούνται με τη μουσική το βιβλίο απο το οποιο ο ίδιος ο Μπαχ έμαθε πως λειτουργει η μουσική.  Εχει γραφτεί απο τον μηχανικό Niedt και δωθηκε στον Μπαχ σε μικρη ηλικία. Οταν το διαβάσετε θα καταλάβετε οτι ελάχιστοι μουσικοί ειχαν προςβαςη η αξιοποίησαν αυτη τη γνωςη οπως Corelli , Vuvaldi, Beethoven, Mendelson, Rachmaninov, Beatles, Pink Floyd, Χατζιδακις, Depeche Mode, Madonna κτλ.


Bach Bass Rules
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf

Hellas is getting out of the crisis

Bravo to the Metro in Athens.


They are reducing the big poster advertisements of horror fiction books.


They are reducing the advertisements inside the trains of bikini bodies blown up in front of the passenger nose.


They are reducing advertisements of cheap snacks, processed food etc made with vegetable or palm oil which have the reputation of clogging blood arteries. On the contrary they are increasing advertisements of health food such as sesame or tahini so that passengers bodies can at become at least as good as the bikini bodies of older advertisements. (Certain subsets of population who take great care in their diet such as monks and photo models are great fans of whole grain tahini).


They are controlling train speed and noise to protect the ears of the passengers.


They are reprogramming good quality music in the train stations.


They have started advertising books that promote in-phobia rather than fear such as the book of philosopher Epictetous.


In fact Epictetous is now a main subject of school curriculum.


It is great that society realizes that it is not only fear, sex phobia, insecurity that sell.


On the contrary, in-phobia, (fear does not exist anyway) help people become happy.


Happy people like what they do and they do it better.


And society prospers.


Bibliography:


Enchiridion - Epictetous


How to stop worrying and start living - Dale Carnegie


Fringe Knowledge for Beginers - Montalk