Removing Mercury from the body with entropy

Diffusion takes place from high concentration to low.


Would immersing the body in clean water do the trick?


Or in other words.


Can entropy be used to get heavy metals from the body


Are bath, water, sea swimming, diving, foot bath some ways?


One needs to get any toxic molecules out of the body. Would entropy work?


When we get ourselves into water, we have the lower toxicity of water absorbing the high of the body.


By getting into the sea we are surrounded by practically infinite amount of water.


There is an excellent lecture by the great physicist Richard Feynman on entropy, called The Distinction of Past and Future:
https://m.youtube.com/watch?v=-Km7-6-J81k

An ultimate test for preamplifier low noise?

Connecting a 200Ω resistor at the input and comparing the noose out to a short circuit at the input?


Or spraying with a freeze spray, or heating the 200Ω with a lighter to determine that the noise is actually the thermal noise of the resistor?

Extra Sensitive Electrometer?

When the cathode of an electron tube starts emitting electrons the grid starts immediately becoming negatively charged with respect to cathode.

In fact the cathode is charged positive as it has lost electrons to the cloud outside of it.

This effect limits anode current at low voltage. Therefore it limits transconductance.

This of course means that the ability of the grid to control current is restricted.

But what if an external source of DC voltage is carefully connected to the grid through a very high Gigaohm resistor.

The negative potential of the grid will be neutralised and anode current will increase together with transconductance ie amplification ability.

The external DC source may have to be quite high so all necessary precautions need to be taken. And the higher it is, the higher the grid resistor that can be used to get the grid from negative to as close as zero volts?

Would by experiment values be found that make the electron tube behave as an infinite impedance to DC? Can the grid leak be omitted as described on the next post?

Is there an opposing grid current source? Could they cancel each other by appropriate choice of external applied voltages or components values?

A variable is also the heater voltage as it beautifully controls or rather creates sensitivity on a Neumann U47 microphone.

These concepts are also used in the Pleiades V series low level amplifiers or microphone preamplifiers using a few only, 6V for example at the anode. On the Pleiades V5 4.7MΩ is connected from anode to grid to free electrons. Pleiades schematics and concepts are open source.

More on the next post...

Positive Grid Neutralisation

This discussion assumes small anode voltage.


It was shown on a previous post that when the cathode of an electron vacuum tube is heated the grid becomes immediately an EMF source of voltage wrt cathode of a 4.7KΩ output impedance. This Zout value is a particular value measured on an EF183 electron tube.


This phenomenon should be possible to be verified on any tube by carefully connecting a heater voltage and then a voltmeter between cathode and grid.


In fact it is the cathode that has become a source of positive voltage as it has lost many electrons to the cloud outside it.


If the secondary of an input transformer is connected directly to grid and cathode all this current (typically 200μA for a EF183) will travel through the secondary back to cathode. The negative voltage on grid that is forced to become zero when the secondary is connected is typically -900mV.


But what if a coin battery is connected in series with the secondary so that it directs grid to the positive (not negative as it is shown in typical schematics working with high anode voltage)? Ie the positive side of the battery towards the grid.


This EMF could be arranged to exactly cancel the EMF inside the tube. And with it the current, that may be more appropriate in this particular case to think of as cathode current rather than grid current. Of course Kirchoff's current law aid us in understanding more. When the tube operates the cathode current should be the grid current plus the anode current. The external return circuits send the electrons back to the cathode.


A value of external EMF may be found that does not affect the DC self assumed condition of the grid whether the transformer is connected or not.


Would this zero external grid cathode current make an even lower noise preamplifier?


The anode voltage may have to be increased from the typical 6V used on previous experiments with Pleiades pre amplifiers.


Would this current null neutralization make an infinite grid input impedance?


Would it make an amazing electrometer?


When grater anode voltages are used is there a grid current in opposite direction by positive ions for example?


Was Georg Neumann trying to balance these two currents in order to get zero current flowing to grid? The variables were, how underheated VF14, the anode voltage, the grid leak resistor etc.


When disconnecting the capsule on the Neumann U47 microphone hiss is so small and beatifully sounding. Almost of velvet like quality without high frequency exaggeration.


There is an excellent paper describing very low noise operation of electron tubes without any grid leak resistor at all.


It appeared on the Electronics magazine shortly before 1947. It is likely that Neumann read it.


A grid leak resistor plays in fact the role of cathode leak? As electrons rush through it to return to cathode from the outside of the tube to cancel the positive potential created by those missing that are making the electron cloud...


Reference:


Open-grid tubes in Low-Level Amplifier - Robert J. Meyer - Electronics - Oct 1944

Yes Happiness Exists, Ναι Υπάρχει Ευτυχία

Il y a du bonheur!!!

Bandwidth needed for flat frequency responce from vocal chords of singer to listeners brain and Pleiades amplifiers

Using a good quality microphone produces a very small flat bandwidth to listeners brain.

The frequency responce curve perceived by ear - brain is one that starts increasing below 1KHz and increasing above 5-10 KHz. (See the next after next euroelectron post).

This is a bathtub curve.

Bandwidth defined as the distance in frequency between the 3dB frequency points is very low although the microphone can reproduce from 50Hz to 18KHz for example.

Flat bandwidth may be even less than 8KHz. The fact that it is an inverse bathtub curve makes matters even worse.

As of writing this the FM radio plays a Toscanini 30s recording. It sounds with emphasis on mid range. 60s recordings sound natural in general. And some modern recordings may sound bathtub like possibly because we have gone to extreme surpassing the flat correct frequency responce need by our brain perception.

There are many factors that explain this. This article is for voice. Voice and few single instruments can sound great on 30s recordings (Rachmaninoff chime self being recorded on the piano for example with cello). This may have to do with Fletcher Manson curves. These effects are important when there is difference between reproduced and recorded acoustic intensity. When recording a full orchestra the reproduced intensity is lower that the original. This gives and inverse bathtub curve on our brain perception.

But let's start with proximity effect first. To see half of a bathtub curve at frequencies lower than 1KHz one can refer to any frequency responce of a directional microphone at small distances from source. Of course we can listen to this by our ears as a muddy and heavy mid, mid bass, bassy heavy responce. Or a heavy responce with no high frequencies as they are dominated and buried by the bass predominance.

Also the pressure doubling effect at high frequency on pressure microphones increases the high frequency content unnaturally. They are best to be used at 45 to 90 degrees, grazing incidence.

As starting to explain above there are other psychoacoustic factors too that exaggerate the bathtub curve. Fletcher Munson curves and voice effort curves explain this.

So an added bathtub frequency responce is added by our brain itself.

This is because the original recorded acoustic intensity, (human voice for example) and the reproduced acoustic intensity (a voice matching a full orchestra) do not match. The reproduced acoustic voice is much louder.

So listening to something louder that it in reality creates another bathtub curve exolained by the Fletcher Munson curves.

The simplest perhaps way to describe the Fletcher Munson curves may be the following. The more acoustic sound intensity arrives to our ears the more more bass and treble heavy the sound is to our brain. And the corollary, the smaller the acoustic intensity the more the brain focuses on mid range. A reason may be survival itself.

An example. A crying babe (see also voice effort curves) can be heared in a dessert at great distance and be rescued.

Now on to the voice effort curves.

Softly speaking which is nice and expressive creates another bathtub curve explained by the voice spectrum effort curves. When we speak or sing loudly, the spectrum peaks at mid range, like a pyramid (inverse bathtub curve). When we speak or sing softly, the opposite ie increase at low and high frequencies, is bathtub frequency spectrum curve. We may try this ourselves even outside of a lab. All we need is our ears and our voice.

So we at least 2-3 bathtub curves to deal with and compensate before we can make a beautiful speech level singing voice sound correct at reproduction to the listeners brain. Fletcher Mansin curves explain what good engineers know and do, for example add a few dB above 2.5KHz to restore presence to voice lost by higher acoustic intensity.

These effects may explain why a flat microphone, flat preamplifier to a flat power amplifier to flat loudspeakers may sound so unnatural.

Great engineers have done great and successful efforts to increase the frequency responce of microphones and loudspeakers to cope with the most demanding transients of a piano.

A piano for example.

This great effort is not to be underestimated. Transient responce is very important.

It is just that when we consider the system as a whole, somewhere in the chain when recording speech level singing voice the bathtub curve need to be compensated with its inverse.

The preamplifier may be a good place.

It is nice to get the signal correct as soon as possible. The closer to source the ways kitty of components dictates the performance of the whole system. (An exemption may be not doing all the low cut need on ribbon microphones on the input transformer to get as much signal to the first tube stage. Other exception are deliberate high frequency preemphasis as used by FM with dee oasis to round any instantaneously clipped peaks in the waveform and make the sound loud due to a increase in average to peak ratio. This is very useful too before going to a analog to digital converter.

But the moment let us assume the signal correct as soon as possible. The closer to the source and the quality of components dictate the performance of the whole system.)

Pultec inductor capacitor equalizers are great tools for this purpose but why not getting the signal sounding right as soon as possible after the microphone. Why not attempting to reduce the number of equipment in the signal chain, reducing the weight, considering economy (including power consumption) reducing the complexity and increasing the quality of the overall system's signal path.

So the interesting fact is that a preamplifier to have an inverse bathtub curve it must have corresponding small inverse bathtub bandwidth to make the voice natural from vocal chords to brain.

Electron tubes on their own FETs and BJTs have an inherent bandwidth from DC to MHz. Surrounding components, (capacitors and inductors), have a reactance that varies with frequency and limit the bandwidth.

Pleiades (open source schematics so that anyone can perfect them) amplifiers use as few active devices as possible. Sometimes as low as just one.

For certain amplications such as voice production the MHz bandwidth is deliberately reduced to a few KHz . This us done by the surounding inductors, including transformers, and capacitors to restore flat frequency responce from vocal chords to listener's mind.

Notes:

Added advantage is the in the increase of signal to noise ratio,

On ribbon microphones it may be best not to do all the low cut compensation need at the inout transformer in order to get as much signal to the first stage. Future research will be useful.

Pleiades preamplifiers have a very low noise performance anyway.

This is because the anode voltage is as low as a few volts from one battery supplying the heaters too.

Cathode is underheted deliberately to keep electron emission cloud at smaller thermal movement and reducing the negative charge by electron cloud being induced to the nearby grid.

It may be stated that the negative bias that we have learnt to apply externally already exists inside a vacuum electron tube. At low plate operation voltage this is of paramount importance and blocks the operation of the tube.

The self assumed remaining negative charge on the grid is discharged by a high Megohm resistor from anode or Vb to grid. A typical value can be 4-8MΩ when Vb is 6 Volts. This frees electron and makes traveling to the anode very easy at very small fields created by a small voltage. So they can carry and convey as much information of a small signal amplified and arriving at its pristine glory at the anode.

Reference: Sound picture recording and reproducing Characteristics - Loye, Morgan - 1939 spring meeting at Hollywood - JMPSE

How would a regenerative microphone preamplifier sound ?

An easy implementation is having a speaker playing back what is being recorded while recording. One must be extremely careful with the ugly sound that can destroy speakers and hearing if the system goes into self oscillation. Gain must be increased very gently. And a limiter somewhere in the chain is very useful.


(In fact a tube with a high grid leak has automatic gain control.


It can be observed on a Neumann U47. (If the capsule is removed firstly one can observe there is very low thermal noise, although one because the grid leak resistor is many megohms). If we connect a signal generator and start increasing the level after some point the level on the output of the VF14 amplifier is not further increased, but the shape of the output is still sinewave. If we reduce abruptly the input signal, the output of the signal starts increasing at a time constant. This limiting action apparently happens when the grid is getting towards being positive, it attracts electrons. It therefore becomes negative. Repels electrons decreasing anode current. So transconductance decreases and with it voltage to current gain.)


With the method of the first paragraph one can get an echo room, reverberation chamber sound.


Other example is the guitar string close to the amplifier speaker effect.


Other example, a Siemens Tekefunken V72, uses positive feedback from one cathode to the other.


But how would regeneration sound on a Pleiades V6 preamplifier?


It can be implemented easily ny taking a single wire, pass a few turns through the toroidal input transformer and and continue to wind the same wire a few turns on the output transformer at the core the correct direction and then joining the two ends together or through a variable resistor. The resistor with vary the cutoff frequency of the positive feedback.


An easier method may be by a resistor from the secondary of the output transformer to the primary of the input transformer.


Or arranging the input transformer to be a hybrid transformer.


If not using a hybrid transformer it would be funny but at oscillation the sound will come out of the microphone.


A hybrid transformer will make possible the addition of the two signals, mic and positive feedback without getting the feedback signal back to the mic.


On second thoughts the membrane of the microphone be aided in movement by the preamplifier to amplify the signal to be amplified sounds nice, one has to be careful.


Regeneration increases selectivity, reduces bandwidth in rf circuits. So distant stations can be heared.


Would a similar sensitivity happen at audio applications?


Bandwidth restriction is a good thing as it makes the frequency responce from vocal chords of singer to the brain of the listener flat, (see next post).

Proximity and Bandwidth

It is interesting how much the frequency responce of a microphone preamplifier must be reduced in order to use for the human voice.


If this is not done the frequency responce from singer vocal chords to listeners brain is not flat. The frequency responce from mic to loudspeaker is only part of the chain [see Hollywood reference].


If a typical studio directional microphone is used at less than a few inches distance the proximity bass increase may begin at as high as 1KHz. It then roughly increases by 6 dB per octave as frequency goes down looking like half of a bathtub curve. Such curves can be readily observed on any directional microphone data sheet in reference to small distance from source


To compensate for this the preamplifier needs to do the inverse. This means the frequency responce of the microphone preamplifier may need to start dropping at 1KHz (-3dB point) with a slope of 6dB over octave below 1KHz. It depends on distance. 3in source to mic may need 470Hz turnover frequency etc.


And this is only part of the story. Additionaly there are the Fletcher Munson equal loudness curves and the voice effort curves.


The first describe how our mind hears, how its frequency response curve changes by intensity.


The second describe how the frequency spectrum of voice changes by how loud we sing.


So after compensating for the proximity effect the bass and treble frequencies may still sound exaggerated to our brain. As an example we may need to gently high cut starting at 10KHz.


This needed process has similarity with the playback de emphasis used to compensate emphasis while disc recording. And it has beneficial results. By reducing treble to get the the flat perception described above, the hiss noise goes down too. And any higher order harmonic distortion of an electron tube, JFET, or bipolar junction transistor decreases too.


One way to implement the high cut is the effective gentle first order low cut filter. The old trick of a C series with R filter across the plate load, the resistor being variable. It can be seen as treble control in schematics of EMI, Emmerson, Dancette tube record changers etc.


This process has another beneficial effect. Reducing high order harmonics means rounding of the extreme clipped peaks that happen all the time when using music signals. Rounding makes them more acceptable and the higher average to peak signal ratio means higher loudness. Similar process to FM radio preemphasis de emphasis.


The above may produce a dramatic increase to signal to noise ratio and loudness.


So the best preamplifier for voice applications that need 3dB points at 1KHz and 10 KHz means bandwidth restricted by 6-7 octaves (from 20 Hz to 1 KHz is 6 octaves and 1 octave form 10KHz to 20KHz) to reproduce correct voice, ie flat frequency responce to brain.


This facilitates extremely the design of input and output transformer.


Very high step up rations may be used. If state of the Art Nanocrystalinne cores such as Magnetec Nanoperm are used which have x100000 relarive to air magnetic permeability, then very few turns are needed.


So they can be wound anywhere by the user to fit the exact application.


The concept of thinking from singer actor vocal chords to listener brain is restated and emphasized. This is knowledge shared by the pioneer sound engineers of Hollywood sharing their 1930's findings on the Journal of SMPE. This concept may explain why some vintage microphones, recordings and preamplifiers shine. Sometimes what we do not do is important.


To return to the topic, lower bandwidth means the gain can be increased in audio transformers.


If we use in the chain as preamplifier front end such as the Pleiades series V one tube preamplifiers, noise further reduces.


The Pleiades preamplifier is open source. Schematics are freely available. And it can also be freely manufactured as all other Pleiades electronic concepts.


It is battery powered, only a few volts are needed. This is made possible by using a high resistor from anode to grid to discharge the grid from the induced negative charge by the nearby cathode boiling electrons. The secondary of the input transfor must be capacitance coupled to the control grid so,as not to influence the grid potential.


The cathode of the electron tube is deliberately underheated to further reduce the cathode steamlike electron emission traffic congestion. Low heater voltage apparently for similar if not more reasons is used on the legendary Neumsnn U47 microphone.


By doing all the above we are left with a dramatic increase in signal to noise ratio. This means even a deliberate faint voice can be amplified in a clean way and without thermal noise hiss. The low and high frequency roll offs that have to be introduced are added by the outside passive components. Electron tubes and other devices are inherently flat from DC to MHz. The surrounding components may be used to advantage to reproduce flat frequency responce to the listener brain.


The turnover frequency depends on application. For example which microphone is used and what distance. If the singing reproduced intensity is different from the actual intensity of the acoustic sound emitted by the singer in the studio.

The point is that of looking at the chain as a whole system (from vocal chords to brain) and taking this into account in the design of the microphone preamplifier.


An attempt is the Pleiades amplifier. By using only one EF183 (triode connected), 2 transformers, an anode to grid resistor, one capacitor and a battery. With it we can possibly obtain the best sounding and quietest from noise signal in the world.


It can be perfected.


The very few components needed between vocal chords and brain make the most natural sound.


The Pleuades pre preamplifier is small, has low power consumption and is portable.


The Pleiade K117 version implemented with a K117 or 2SK117 JFET fits inside the female microphone connector and the other side of the audio cable gets phantom power when connected for example to iPad GarageBand or any mobile device that can power electrets.


The fact that dynamic microphones have their broad band reasonance in the mid band (resistance control of reasonance), greatly synergies with the above concepts.


Ribbon (reasonance at low frequency) as they are mass controlled and condenser and crystal microphones which have the disphragm reasonance at high frequency as they are stiffness controlled are excellent microphones too and can sound very natural and low noise too using the above concept.





Reference: Sound picture recording and reproducing characteristics - Loye, Morgan, Journal of motion pictures sound engineers

Pleiades electron tube RF amplifier and oscillator with battery operation

It would be nice to make a Hartley oscillator with an electron tube that operates at only 6V.


It may be possible by canceling the self assumed negative grid voltage using a high Megohm resistor from plate to grid. The same technique that is used on the Pleiades V series microphone pre preamplifiers for low noise and battery operation. Deliberate reduced heater voltage may be used too to reduce noisy electron cloud near grid as explained on previous euroelectron posts.


Using grid leak bias a very low noise and pure sinewave oscillator may be made. Can the high Megohm resistor play this role too stabilizing gain by automatic gain control. On the Neumann U47 the much higher Megohm resistor provides automatic gain control and it is connected from grid to ground.


How about an audio frequency oscillator like this, one oscillator for each musical note. Intonation can be great by tuning correct to the human mind high octaves which need to be stretched in frequency for correct musical pitch.


An RF front end preamplifier could be made using the same principles. Reduced anode voltage and heater voltage makes a very quite preamplifier. If it can hear the subtlest and quietest sound of the human voice from a ribbon microphone with very low hiss why should it not pick the furthest faintest radio signal from space?


A simple receiver could be initially tried with 2 aluminum foils separated by an A4 paper for dielectric. In parallel connected could be 60turns wound on kitchen paper bobbin. A capacitor coupling to the electron tube grid. The other side of the coil capacitor combination to ground and cathode. A high Megohm resistor from anode to grid. An output transformer from battery plus to anode. The cathode connected to ground. The secondary of the output trasformer to a mic input. Antenna connected to the coil. Underheated cathodes, optimum temperature (heater voltage) found by experiment. A regenerative receiver would be interesting as such a low noise electron tube topology feeding back to itself may produce lesser noise and high sensitivity.


A suitable tube is a triode connected EF183 as on the Pleiades V series pre preamplifiers.

Pleiades Public Domain

Everything Pleiades is free of copyright, royalties...


Anybody, companies can use anything Pleiades including for commercial purposes.

Pleiades Electra headphone amplifier with ordinary tubes?

It may be possible by using a high Megohm resistor from plate to grid as is done on the Pleiades V series preamplifiers.


On a previous post the principle was mentioned as a Pleiades V6 preamplifier was used to drive 150 ohm headphones through its output trasformer.


The influence of the 8.2MΩ resistor to free electrons was tested and made a dramatic difference. When it was disconnected the 100μA anode current dropped to almost zero and sound almost became inaudible. this is because without it the grid self assumes a high negative potential, typically hundreds of -millivolts which restrict the passage of electrons to the anode at low anode voltage.


Cathode was connected to ground as usual.


The sound quality was beautiful but more power is needed.


Power supply was 5.8V for the anode and aproximately 3V for the heaters.


Further experiments need to be done.


It may prove possible to connect 300Ω headphones directly to the anode without an output transformer.


Changing to 12V as is used in other Pleiades Electra headphone amplifiers may make a lot of difference in power output and lowering of output impedance.


A 12SK7 gives perhaps more than 1mA at 12 Volts with the trick of positive grid neutralization.


Other candidate tubes can be 6SK7, 6K7, EF86, ECC82, E88CC...

Μαγικο γλυκό σάντουιτς

Με ώριμο αβοκάντο οπως το σάντουιτς της Λουσυ, Αγγελικής, Παναγιώτη


Ψωμι ολικής με προζύμι κσι χωρις λάδι
Αβοκάντο απλωμενο κσι στις δυο φέτες με πιρούνι
Μαύρη σταφίδα
Μικρά κομματάκια καρυδιού
Κανέλλα Κευλανης
Σουςαμι ολικής


Περιγραφή στο επόμενο euroelectron post στα αγγλικά

Pleiades magic sandwiches

At your own risk.


1st
Ingredients:
Top quality whole sliced bread with no oil
Whole grain tahini
Nettle dried leaves
Pepper
Top quality salt
Black resins


2nd
(Based on the sa witch made by Lousy, Angeliki, Panayiotis)
Ingredients:
Mature Avogadro spread by a fork on both sides of bread
Dried Nettle leaves
Rosemary
Top quality salt
Pepper
Black resins


3rd
Sweet magic sandwich
Ingredients:
Top quality whole sliced yeast bread
Mature Avogado spread by a fork on both sides of bread
Black raisins
Ceylon Cinamon
Small pieces of walnut
Whole grain sesame

How to reform vintage electrolytic capacitors

At your own risk, take all precautions.


Vintage electrolytic capacitors can be reformed by carefully connecting them close but not higher than rated voltage through 1 Megohm resistor for a couple of days until the voltage across the capacitor very nearly equals the voltage source.

Sennheiser MD21 HL directly to Sony TC-D5 Pro through Pleiades filter or through Pleiades V6 pre preamplifier comparison

description is to be found on the 2nd previous in time post

Active dynamic microphone

please refer to the previous in time post.

Compensating for increased perceived bass by varying the heater voltage on electron tubes

It is great that audio engineers have always used not only their ears to listen but also their mind and their heart.


Any world class microphone such as the Sennheiser MD21 can sound bass heavy to our mind due to many psychoacoustic effects of our brain perception.


The Fletcher Munson curves and the voice effort curves are two reasons and there are more. And of course directional microphones have the proximity effect too which is not the case with omnidirectionals such as the MD21.


While testing in the past various Pleiades filters (inductors in parallel with the microphone) an inductance of 85mH was found to produce very natural results on male voice for the MD21 HL. The voice is very clear, not bass heavy and psychoacousticaly it sounds deep presumably as the mind is now not disturbed by exaggerated lows.


Assuming a 200Ω microphone output impedance this inductance corresponds to aproximately a 380Hz cutoff. The filter created by the R and L is first order and gives a gentle slope of 6dB per octave in reducing bass.


While testing the Pleiades V6 preamplifier with a flat input trasformer (Altec 4722) and a Pleiades output trasformer that gave a similar cutoff when driven directly by the EF183 electron tube the same pleasing and natural effect was observed on voice.


The Pleiades V6 is possibly the simplest microphone amplifier using an input trasformer, an electron tube and an output trasformer directly connected to the anode.


A coupling capacitor connects the input trasformer to the control grid so as not to disturb the grid potential.


A high megohm resistor from anode to grid, 8.2MΩ, neutralizes the grid from its negative self assumed potential due to electron cloud emitted violently from the cathode.


This Rag resistor allows operation of the tube at a typical plate voltage of 5V.


Operation is very quiet as it is battery powered with same battery (6V in these experiments) for both heaters and plate circuit. The Vb is connected directly to the other side of the primary of the output trasformer.


The cathode is connected directly to ground. This maximises gain due to no negative feedback cathode resistor and further increases simplicity.


2 setups were used for sound comparison on male speech and singing voice.


1st setup:


MD21 HL at Low Z - Pleiades 82mH - Sony TCD5 PRO - Sennheiser HD580


2nd setup:


MD21 HN at Low Z - Pleiades V6 preamplifier - Sony TCD5 PRO - HD580


Anode current on the triode connected vari μ electron tube was from 100μA to 200 μA. This was varied by varying the rheostat in series with heaters to battery.


Although the heater voltage is specified at 6.3 volts only for example 3 volts is a typical value used and varrying around this.


It is known that underheating an electron tube cathode gives a very nice sound quality to a microphone amplifier and a legendary example is the underheated VF14 tube on the Neumann U47 microphone.


The sound appears much more focused and the low noise produced is a joy to observe.


The apparent reduction in noise may be explained by less cathode to grid induced current (see earlier euroelectron posts). The cathode electron cloud may resemble a boiling water steam cloud. This seems relevant at such small input signals to be amplified. On the Neumann U47 operating at higher plate voltage there must be other phenomena too, reduction of secondary emission? Etc. it was also observed in previous experiments that at some sweet value of cathode temperature perceived voice output maximizes.


This maximum occurring at slightly less than Ia=100μA was objectively verified as a 3dB increase on the VU meter of a Realistic disco mixer on previously described setups. The best way to observe gain increase while cathode temperature lowers is as follows. The heater rheostat bypassed. The cathode heats at full 6 Volts. Then the heaters are disconnected. (Actually whenever heaters are disconnected an jump is anode current is observed). With heaters disconnected the anode current is normally decreasing from about 400μA. When it reaches aproximately 100μA the gain increases by about 3 dB. This experiment was conducted on previous setups while a 440Hz square wave constant acoustic source was at constant distance to a Grampian ribbon microphone.


Continuing on today's experiment, while varying the heater voltage, i.e. the cathode temperature, it was found that the low frequency cutoff point was changing by listening on the headphones.


It was then confirmed by connecting an on attenuated portable Sony CD player with as test disc, connected to the Altec transformer. Response was observed on the Sony TC-D5 VU meters. Throughout all tests the TC-D5 was switched to mono operation so that the voice could be heard on both channels.


The change in 3dB cutoff point varied from 300Hz to less than 500Hz.


Values greater than 300Hz produced with less heater current gave a more focused sound on voice and a natural quality that is hard to describe with words.


The change in frequency responce is explained by the change in the output resistance of the electron tube as gm (transconductance) reduces with less anode current.


So the heater voltage can be used as a methods to adjust for compensation in perceived bass increase.


With a heater voltage that gave the same subjective bass naturalness on both setups their sound could now be compared more effectively.


While the 1st direct to Sony setup gives a world class sound quality there seem to be 2 advantages on the 2nd setup.


It sounds much more noise quiet and when the microphone is connecte one is surprised by low loud and sensitive the microphone sounds.


On the 1st setup the Sony recording level potentiometer has to be at 10 (maximum value).


On the 2nd setup,it has to be at just 2 for the same VU meter responce. So any noise generated by the Sony preamplifier is almost completely minimized.


The Pleides V6 with the above mentioned techniques is very quiet.


In fact the sensitivity of the MD21 is now comparable to the AKG C24 which has to be operated too at comparably very low potentiometer setting on Sony TCD5.


Although the bass responce on both setups is now similar the 2nd setup seems to have a more focused quality with the voice ready to jump at the listener.


This may be explained by the big signal, that drives the Sony input trasformer and input electronics.


Further tests need to be done.


And it must not be overlooked that setup 1 is much more simple and consumes much less power.


A very portable setup is using the Pleiades K117 JFET preamplifier inside the mini Tuchel connector of the MD21 HL. The output of the MD21 HL (Hi Z connection) internal step up transformer is connected directly to gate. The resistor and power supply comes from the device it is connected to, eg iPad. The iPad when using GarageBand introduces a similar around 400Hz cutoff. This makes a world class and simplest setup that is very suitable to the MD21 HL.


The world class MD21 HL was used at aproximately 1 inch and at 45 degrees from mouth.

USB Pleiades microphone electron tube pre preamplifier

It may be possible with an extremely low noise preamplifier such as the Pleiades V6. Phantom powering may be an option too.


The EF183 for example operates at about 5V including anode supply voltage when a resistor of a few megohm is connected from plate to grid to free electrons.


It operates even better when it is underheated so 150mA should be fine and possible for USB powering or phantom powering.


So it would be nice to make a whole small unit including a top quality analog to digital converter.


The Pleiades K117 JFET is great too as it can be made inside an XLR connector or a small Tuchel connector and take the high impedance of an MD21 HL for example and feed directly an electret mic input. Such inputs are on any device like iPad and can supply power directly to the  JFET through their load resistor.


So we can have a world class extremely low noise studio quality pre preamplifier at minimum weight and power consumption and maximum portability.

Ένας κανόνας υγειηνης διατροφής; A simple rule for healthy eating?

Θα μπορουςε να ειναι ο παρακατω;


Το τρως με τα χέρια και δεν λερώνεσαι; Η το πιάτο πλένεται μόνο με νερό και καθαρίζει;


Για παραδειγμα σάντουιτς με ψωμι ολικής χωρις λάδι, ταχίνι ολικής και ξηρούς καρπούς, μαύρη σταφίδα κτλ.


Could it be the following rule?


That one eats it by hands and hands do not get dirty.


Or that the plate can be cleaned with just water.


Example a sandwich with whole bread without oil, tahini, and various nuts, black raisin eye.

Η Κανελινα και τι δεν ειναι επιστήμη

Η Κανελινα κοιμάται κοντα στην κουκουτσιά.


Η κουκουτσιά φτιάχνει απίστευτα κουκούτσια με μανταρίνι. Ειναι όξινα και άρα μάλλον έχουν πολυ ασκορβικο οξύ που ειναι η βιταμίνη C. Τρώει ενα καθε μέρα και δεν αρωσταινει. Αν ποτε αρρωστήσει γινεται καλα με ενα τέτοιο η με ενα νεράντζι στημένο σε ενα ποτήρι νερό. Η ανακάλυψη της βιταμίνης C και ο συσχετισμός της με τη ενίσχυση του ανοσοποιητικού συστήματος πήρε βραβείο Νομπελ. Φυσικά δεν ειναι τυχαίο που τα εσπεριδοειδή ευδοκιμούν το χειμώνα. Ειναι για να γινόμαστε αμέσως καλα πριν αρρωστήσουμε.


Η Κανελινα έκλαιγε απο χθες γιατι οι άλλες γάτες την ειπαν εμπειρική.


Το πρωί αφού έφαγε κουκουτσινι με μανταρίνι και ψωμι ολικής με ταχίνι ολικής και καλο μέλι κατέβηκε αμέσως στην παραλία να βρει τους δυο σοφούς γλάρους στον μαγικο βράχο μεςα στο νερό.


Να σου θυμίσουμε Κσνελινα οπως λέει ο Ντέιλ Καρνεγκι στο βιβλίο του, μόνο ένας χαζός κατηγορεί τους άλλους. (Only a fool criticizes, condemns or complains).


Η Κανρλινα άρχισε να σκουπίζει τα δάκρυα της.


Απλά να έχεις χαμηλό προφίλ συνέστησαν οι γλάροι.


Πολυ μεγάλο μερος της αναζήτησης της ανθρωπότητας για γνώση (επιστήμη) οφείλεται στην εμπειρία και στην παρατήρηση, στο πείραμα.


Ο μεγαλύτερος ιςως θεωρητικός φυσικός και δάσκαλος ,ε την έννοια του καθηγητή πανεπιστημίου, Richard Feynman λέει οτι οι καλύτερες θεωρίες που εξηγούν την παρατήρηση ξεκινούν συνήθως με μαντεψια (guess).


Η θεωρία του Feynman, Κβαντο Ηλεκτρο Δυναμικη (QED, quantum electrodynamics) πήρε βραβείο Νόμπελ. Περιγράφει χρησιμοποιώντας σκίτσα σαν κινούμενα σχέδια (Feynman diagrams) πως συμπεριφέρονται ηλεκτρόνια και φωτόνια. Ετςι λύνονται πολυ δύσκολες εξισώσεις που αλλιώς θα απαιτούνταν παρα πολυ προσπάθεια.


Μια θεωρία αντέχει μέχρι να διαψευστεί απο το πείραμα η να συμπληρωθεί. Παραδειγμα η θεωρία του Αινσταιν που συμπληρώνει του Νεύτωνα για πολυ μεγάλες ταχύτητες.


Σύμφωνα με τον Carl Popper επιστήμη ειναι οτι μπορεί να διαψευστεί. Τα υπολοιπα δοξασία.


Ειναι εντάξει λοιπόν να είσαι εμπειρική και να ψάχνεις την αλήθεια να βρεις.


Διαβάζουμε φυσικά οτι κρίνουμε καλο, αλλα πειραματιζομαςτε και με το μυαλό και έχουμε κριτική ικανότητα. Ειμαςτε καλοί δεκτές κσι πομποί. Με χαμηλό προφίλ, για να μην κάνουμε τους άλλους να αισθάνονται άβολα.


Και δεν οικειοποιούμαστε τίποτα για να έχουμε πρόσβαση στα παντα.


Η αγάπη οπως είπε ο Feynman ειναι πιο συμαντικη στο οποιαδήποτε εξίσωση.


Κσι μην ξεχνάς Κανελινα πως πρώτα παρατηρήθηκε πως εμείς οι γλάροι πετουμε πλαναρωντας με δυναμική άνωση κσι μετά έγινε το αεροπλάνο.


Πετάχτηκε η Κανελινα απο χαρά.


Ειρθε και ο γάτος με την πρασινη κορδέλα κσι όλοι μαζι χόρεψαν κσι τραγούδησαν κατω απο το φως του μαγικού Ηλιου που δεν αφηνει καμια σκιά στην αλήθεια.



Πηγές:


Richard Faynman on YouTube


How to make friends and influence your environment - Dale Carnegie - free pdf

Variable proximity effect compensation by varying the load of the output transformer

This is in reference to the previous euroelectron post.


The Pleiades V6 microphone preamplifier  with the EF183 electron tube is in a single ended output transformer configuration. It operates in class A, ie electrons flowing all the time. DC current is passing through the primary of the output transformer as it is connected directly to the anode instead of using an anode load resistor.


It was verified as expected that by decreasing the load connected to the secondary of the output transformer the bass responce increases while gain decreases.


It may prove simple and effective to have a potentiometer as a variable load resistor at the output.


In this way the cutoff frequency can be adjusted compensating for the proximity effect at various distances from mic to source.


Effectively it behaves as an equivalent to the focusing adjustment of a camera for close up (macro) photography.


Different time constant for different sound object distance for a flat (focused) frequency responce.

Pleiades V6 with Pleiades output transformer measurements

It is interesting.


By implementing the time constants (low cut usually) on the transformers themselves the transformer design and making is extremely simplified. Very few relatively turns are needed. Sooner or later a young person will be able to make a world class electron tube, JFET or bipolar transistor microphone preamplifier at home including the input and output transformers.


Only one electron tube was used. The legendary EF183 used on Pleiades V4 and V5.


As the V6 is in experimental stage, connections were in breadboard (surrounded by a metal opened box), including Neutrik XLR male and female chassis connectors.


Anode current: 100μA.


Supply voltage, Vb=5.8V


Anode voltage is very close to Vb as the output trasformer (carrying the anode current) is connected directly to anode. Very similar to single ended class A triode 300B power amplifiers. The stage of course behaves as an extremely low noise front end preamplifier.


Heater voltage Vh=3V


The low noise performance of the V6 is described earlier on euroelectron.


This time it was time to listen to the other extreme driving directly 300Ω headphones. The Sennheiser HD580 was bridged to mono with a special XLR female to headphone connector cable. So the load impedance is 150Ω.


Setup:


Sony portable CD player headphone out - Canford red high to low trasformer inside 1/4in jack - Altec green 4722 step up - coupling capacitor - EF183 triode connected with 8.2MΩ from anode to grid - Pleiades Magnetec 070 16H:140mH output transformer - Sennheiser HD580


CD used: Ray of Light - Madonna


It sounded nice!


Louder than expected.


It was easy to overload now by increasing the volume out on the CD player headphones out. The distortion was a nice electron tube distortion.


Substituting the Altec 15095 the distortion was worce as the low frequency responce was more extended due to its very high primary inductance.


It was then decided to drive a microphone input again instead of the headphones.


Setup: as above but stereo disco mixer included.


Sony CD - Canford red - Altec green - EF183 (8M2 from anode to grid) - Pleiades 070 - realistic disco mixer - HD580


CD used : audio test CD from the Ηχος magazine with tones from 20Hz to 20KHz


As now the load impedance (the disco mixer input impedance) is 5KΩ, both transformers are expected to have a worst case scenario low frequency response.


With the Altec output transformer the 3dB point was at 100Hz and 10KHz.


With the Pleiades Magnetec 070 (with relatively few turns) the 3dB points were 340Hz and 11KHz.


The high frequency cutoff made be due to the Altec or Canford input trasformer. The Canford was used as a step down trasformer to reduce the signal, as much as possible. A resistor pad should have been used.


The 350Hz cutoff was very promising and since it represents the cutoff used on the Pleiades filter to make the Sennheisr MD21 sound very natural on voice,a Sennheiser MD21 HL was decided to be connected. On previous experiments the 380Hz, 6db per octave high pass was implemented with a 82mH Pleiades filter in parallel with the microphone output.


New set up:


Sennheiser MD21 used as low impedance - Altec input trasformer - EF183 (8M2 from Plate to grid - Pleiades Magnetec 070 output trasformer - realistic disco mixer mic input - Sennheiser HD 580


The sound on make voice, speech or singing was amazing. So natural that it sounded as the microphone instead of cable was connected to and acoustic waveguide of flat frequency responce, the other side of the waveguide touching the ear.


With the Altec output trasformer the voice was bass heavy as expected and ambient low frequency rumble could be heard.


The MD21 sounded so detailed and sensitive that sounds from very far could be heard as is the case when testing condenser microphones.



Conclusion:


A flat input trasformer can be used on a Pleiades V6 one electron tube one battery pre preamplifier and a Pleiades bass compensating trasformer this time at the output of the Pleiades pre preamplifier.


Or if a Pleiades compensating input trasformer is used (82mH primary inductance in the case of MD21)...


Then the output trasformer could play the role of a second time constant to simulate a tape recording amplifier pre emphasis. Another combination may be a flat input trasformer and a high cutoff at the output trasformer. Then an integrating circuit (post emphasis) and integration stopped at the proximity effect frequency as explained on a previous euroelectron post.


This would allow the making of the output trasformer very easy as the time constant to simulate 30ips tape recording use is a high pass filter at aproximately 10KHz.


The output trasformer can now become an interstage step up transformer. Its secondary simulating playback (coupled coils without tape use). The interstage trasformer can drive another EF183 battery powered amplifying stage.


In fact a transformer is like a record head kissing a playback head on the air gap! It may be interesting to experiment with two magnetic tape heads mounted in such a way at the one touches the other to the lips thereby completing the magnetic circuit. The air gap may be useful since DC current is passing from the anode of the driving electron tube. But winding both coils on a toroidal Magnetec or other core is great too. In this way both coils are hugging each other and music passes on from the one to the other with the aid of the electrons dancing inside the magnetic circuit!


Then at instantaneous playback a low pass filter on the other electron tube stage with a 3dB point at 10KHz can be used to get back to flat frequency responce. The advantage is rounding off of any instantaneous peak limiting waveform by the high cut action (sharp edges are created by high overtones) and making tape simulation sounding as expected. Loud and big.

A musical instrument with just inductance capacitance LC filters?

At your own risk.


How would it sound like?


A keyboard.


For each keyboard note a toroidal coil in parallel to a capacitor.


For example the capacitor connected to the voltage supply and when the key is pressed it is connected to discharge through the coil.


So each electrical resonator for each note.


All resonators connected to a high impedance FET or electron tube amplifier?


Will it sound like a percussion instrument, each LC naturally decaying?


One can hear a note even by simply connecting a capacitor across the primary of an output transformer, the secondary being connected to a speaker. And just a battery. One must be very careful as the back EMF of inductors can be a very dangerous voltage. Always one hand in the back pocket.


This may be a Pleiades musical instrument.

Measuring self assumed grid voltage and current on an EF183 electron tube

The only connection to the EF183 being the heater voltage.


Heaters supplied by Vh=5.9V.


Then a high impedance digital multimeter was connected between grid and cathode.


When the cathode is heated at max temperature:


Vg=-855mV !!


Ig=-185μA !!


In fact when measuring current from cathode to grid in this way we effectively short circuit from cathode to grid.


So by Thevenin's theorem the grid to cathode terminals behave like a voltage source of output impedance Vg/Ig.


This is aproximatelly 4.7KΩ !!


So in fact when we measure grid current in this way we effectively measure cathode emission current intercepted by grid. A nice simulation to see emission is by keeping a glass under hot water for a few seconds and then holding the glass and observing the steam coming out violently in a cold room.


When the cathode temperature is gradually reduced by disconnecting Vh, Ig decreases but Vg initially is reduced and then remains constant at about -300μV (systematic error?, why does it not stay at -800mV?).


The value stays constant as the cathode to grid structure is a charged capacitor.


So at cold heater temperature Vg/Ig approaches infinity ie the grid to cathode output impedance approaches infinity.


Of course when Vg is short circuited to become zero and then the electron tube cathode is heated we observe the grid potential gradually decreasing from 0V until it stabilizes at -855mV with the Vh voltage used.


These observations explain why a grid bias resistor from a positive source is needed to neutralize the control grid and make possible the electron tube operationing at small transistor like voltages. Very low noise performance can be obtained too as observed on the Pleiades V series preamplifiers. (Reduced cost, low power consumption and small weight is an advantage too dispensing with complicated and noisy power supply in favor of just a noisiless single battery for both heater and snode).


These observations also explain why when reducing the heater voltage on the Pleiades V6, V5, V4 series preamplifiers the gain increases and noise goes further down. As is done on the Neumann U47 microphone with its underheated VF14.


It is a great playing with electrons.

How would an analog FM synthesizer sound like?

A good candidate is the Exar XR-2206 sinewave and not only function generator IC which has provision for frequency modulation.


One could connect an analog synthesizer as the modulating signal to save much work.

Analog simulation of magnetic recording with Pleiades filters

By studying a magnetic tape reel to reel electron tube recording amplifier schematic (example Ferrograph series 6) one observation is:


That the high plate resistance of the driving tube is directly connected to the recording head coil. So we have a high pass filter, rising in voltage at 6dB per increasing octave, defined by the output resistance of the tube stage at the inductance of the recording head.


This is exactly the same way the Pleiades microphone filter operates, creating a rising 6db responce defined by the microphone output impedance (usually 200Ω) and the Pleiades filter inductance. The R and L define the 3 dB cutoff point to compensate for the proximity bass increase effect.


Now back to magnetic tape recording.


We have a rising recording voltage characteristic, or constant current into the coil. The is the premphasis. Cutoff points are usually defined by the time constant in microseconds. For example the IEC standard for 7.5ips speed is 70microseconds. (Strictly speaking the curves defined by standards are playback characteristic curves, of course the same time constant must exist during recording).


It is very easy to calculate R or L from the time constant. We know from high school physics that Farad x Ohm is Second and Henry decided by Ohm is Second.


So inductance is time constant x resistance. L=TxR


So for a 200Ω microphone for T=70μS we need a Pleiades filter of


L=70μS x 200Ω = (70 / 1000000)S x 200Ω = 0.014 SxΩ = 0.014 H


So we need 14 milliHenries


An audio (input for example) transformer with 14mH primary inductance is very easy to make as it needs just a few turns for the primary.


So we have a characteristic similar to recording on tape. Then after the signal passes through some tube stages, (the preamp itself) we integrate or high cut to get back to flat frequency response.
As is done on tape playback amplifiers.


This process should do instantaneous peak limiting with rounding of the waveform from the high cut filter.


In fact a very similar process is used by Mike Oldfield to get his guitar sound as explained on an interview.


Since for the mic there is also the proximity effect to take care off we must stop integrating at the time constant of the proximity effect which depends on the distance for source. This may be done by adding a resistance in series with capacitor which is used for high cut at playback


Even for an omnidirectional mic this may about 300-380Hz. (For an MD21 a Pleiades filter of 82mH makes a very natural male singing sound).


The above example is for using the tube gentle curvature for peak limiting and increasing average level.


If we need to to do this magnetically as in tape recording we much arrange to saturate gently a transformer in the signal path. In constant current high pass way as explained above.


In the meantime how would a Pleiades V5 preamplifier sound connected directly to the high impedance output of a portable Sony CD player.


The time constant should be very small corresponding to what premphasis is used for speeds as high as 30ips and more.


A capacitor in series with a resistor must be connected across the anode resistance of the V5 output tube to get back to flat frequency responce with the added advantage of rounding any instantaneously peak limited waveform as on tape recording and playback.


References:
Sound Recording Practice - Borwick
www.261.gr

Πρώτα γίνεσαι ο πιο ευτυχισμένος , First you become the happiest

Πρώτα γίνεσαι ο πιο ευτυχισμένος άνθρωπος στη γη και μετά βρίσκεις το ταίρι σου.


First you became the happiest human on earth and then you find your sweetheart.

The 2nd octave of 1000Hz is 4200Hz? Η 2η οκτάβα της 1000Hz ειναι 4200Hz;

Find out yourself.


Make sure you keep the volume down to protect your ears.


Try on Google (online signal generator).
http://onlinetonegenerator.com is an amazing website.


Choose sinewave.


Input 1000Hz for a few seconds so that you can remember.


Then try 4000Hz.


Go back to 1000Hz and try higher than 4000Hz until you find a satisfactory 2nd octave!

Η επιτυχία ειναι να μην χρειάζεσαι χρήματα

The greatest success is not needing money 

Η Κανελινα το ημιτονο και το wobbulator

Η Κανελινα συναντιέται με το ημιτονο.


Καλημέρα.


Ξέρω ποιο είσαι. Αν περιγραφεις ηλεκτρική τάση και σε συνδέσουμε με ενα μεγάφωνο ανεβοκατεβαίνει η μεμβράνη και ακούμε τόνο, τη συχνοτητα σου.


Μπράβο Κανελινα. Και εσυ που είσαι γάτα ακούς μέχρι πολυ υψηλές συχνότητες.


Ακομα πιο πολυ, προσέχω τα αυτιά μου πολυ.
Και επισεις γνωριζω οτι άλλο συχνοτητα και άλλο ύψος τόνου. Συσχετίζονται αλλα δεν ειναι το ίδιο, το πρώτο ειναι αντικειμενικό το δεύτερο αφορά την αντίληψη στο μυαλό.


Τι; Το γνωρίζεις και αυτο; Τι γάτα είσαι εσυ.


Φυσικά, αν παίξεις μια συχνοτητα αλλα το κανεις με μεγαλύτερη ένταση ο εγκέφαλος ακούει λιγο πιο χαμηλό τονικα τόνο, λιγο προς το ύφεση.



Μπράβο Κανελινα. Ετςι οταν τραγουδάς βάζεις τα ακουστικά η το ηχείο οςο σιγα πρεπει για να μην ακούς λάθος άρα και τραγουδάς φάλτσα.


Ναι, οι γάτες στο εξωτερικό και παλιά στην Columbia το γνώριζαν. Τώρα το είπα και στον γάτο με την πραςινη κορδέλα και ακομα και αυτός τραγουδά καρφί τις νότες.


Μπράβο σας. Τι κανει η υπομονετική χελώνα;


Τυλίγει τα πηνια των φίλτρων με υπομονή. Τι κανει η συναρτηςη δέλτα;


Ειναι άφοβη και έχουμε γίνει φίλοι.


Για πες μου πως μπορω να παίξω μαζι σου;


Ειναι απλό. Βάλε στο Google (online sine generator). Βγαίνει αυτο: http://onlinetonegenerator.com
Γράψε οτι συχνοτητα θελεις και θα με ακούσεις.


Επισεις μπορείς να παίξεις με το wobbulator. Σαν αυτο που ειχαν στο BBC οταν η Delia Derbyshire (προφέρεται Ντιλια Ντερμπισερ) έκανε με τους συνεργάτες της το μουσικο θέμα της σειράς Dr. Who. Θα το βρεις και αυτο virtual online να παίξεις. Βάλε στο Google (online Wobbulator).
Μου μεταβάλει γρήγορα τη συχνοτητα και με ζαλίζει αλλα μ' αρέσει: http://webaudio.prototyping.bbc.co.uk/wobbulator/


Μπα; Και πως γινεται αυτο;


Ειναι σαν με ταρακουνάει κάποιος την ώρα που τραγουδάω τον τόνο μου. Ζαλίζομαι λιγο αλλα μ' αρέσει. Αυτο με κανει να περιέχω πληροφορία.


Ναι σκέτο ημιτονο δεν περιεχεις και πολυ. Ακομα και για να σταλούν σήματα Μορς πρεπει κάποιος να σε διακόπτει συνέχεια. Το ίδιο κσι οταν κατεβάζουμε η ανεβάζουμε απο το Ίντερνετ. Το modem σε διακόπτει συνέχεια για να σταλεί καθε bit (binary digit) 0 η 1.


Μπράβο. Αλλα στην περίπτωση του wobbulator με αφήνουν να τραγουδάω οςο χρειάζεται και αυξομειώνουν τη συχνοτητα μου αναλογικά. Η μεταβολή περνάει απο όλες τις απειρες τιμές. Μεταβάλουν λοιπόν τη συχνοτητα μου. Αυτο λέγεται διαμόρφωση συχνότητας η frequency modulation η FM. Ετςι λειτουργεί και το ραδιόφωνο FM που εφεύρε ο Edwin Armostrong για να μεταφέρεται η πληροφορία. Αυξομειώνεται ο ρυθμός με τον οποίο χορεύουν τα ηλεκτρόνια στην κεραία του πομπού με το ρυθμό της μουσικής.


Πεταχτηκε ενθουσιασμένη η Κανελινα. Και frequency modulation ειναι αυτο που κανει μια τραγουδιστρια οταν κανει vibrato. Η ο βιολιστής η κιθαρίστας οταν κουνάει περίεργα και δεξιοτεχνικά το δάκτυλο πανω στη χορδή. Αυξομειώνει τη συχνοτητα.


Μήπως και η μετατροπεια απο κλίμακα σε κλίμακα οταν συνθέτουμε ενα τραγούδι να λέγεται διαμόρφωση απο το ενα κλειδί στο άλλο; (modulate from one key to another). Τώρα που τα ωδεία αρχίζουν να γίνονται τα καλύτερα...


Βέβαια, και η ΕΡΤ ξεκίνησε εκπομπές που εξηγούν πως φτιάχνονται ομορφα τραγούδια. Σκίζει η ΕΡΤ.


Επισεις στο Google με λέξεις κλειδιά (online drum machine) μπορείς να παίξεις με ρυθμούς που σου αρέσουν.



Και αν θελεις να παίξεις με τους αριθμούς με μένα μπορείς απο αυτο το website:
http://js.do/blog/sound-waves-with-javascript/


Το βρίσκεις γράφοντας στο Google (Online JavaScript FM of sinewave).


Σε αυτο μπορείς να αλλάξεις το ορισμα μου η μεταβλητή που ορίζει την συχνοτητα μου. Μπορείς να βάλεις εκεί ακομα κσι μια άλλη συναρτηςη για να με μεταβάλεις. Αυτο λέγεται συνάρτιση της συναρτισης. Και ετςι στο website αυτο θα ακους προγραμματίζοντας online σε JavaScript που ειναι η γλώσσα των app (application η εφαρμογή η προγραμμα) του internet.


Μπορείς λοιπόν να με ταρακουνάς με μαθηματικό τροπο και να κάνω διαμόρφωση συχνότητας. FM οπως λειτουργεί το συνθεσάϊζερ DX7 της Yamsha κσι τα Casio CZ που κανουν phase modulation η διαμόρφωση φάσης. Με αυτα έχουν γίνει τοςο ομορφα Τραγούδια.


Καταχάρηκε η Κσνελινα.


Κσι όλοι μαζι κατέβηκαν στην παραλία.


Είχε συννεφιά και αέρα. Οι σοφοί γλάροι βρήκαν την ευκαιρία και έκαναν το αγαπημένο τους παιχνίδι. Ειχαν ανοιχτά τα φτερά τους και εωρουνταν με δυναμική άνωση ακίνητοι πετώντας πανω απο το έδαφος. Βρηκαν ευκαιρια κσι μάθαιναν τα μικρά τους να πετούν.


Έκανε το ίδιο κσι η Κανελινα το ημιτονο, η συναρτηςη δέλτα, ο γάτος κσι η χελώνα. Η χαρά τους τοςο μεγάλη που η ψυχή τους πετούσε άφοβη. Και σκέφτηκαν τα φωτόνια του Ηλιου απο το διάστημα και τα ηλεκτρόνια στη γη που τα περιμένουν με αγάπη να έρθουν να αγκαλιαστούν.


Και όλοι άρχισαν να χορεύουν Ray Conniff και το τραγούδι των 80s electric dreams - Oakey, Moroder αναμένοντας τον Ηλιο που δεν αφηνει καμια σκιά, παρα μόνο χαρά.

Horn loaded microphones?

The membrane of a microphone has a different impedance than air.


This makes a mismatch with reflection of energy.


A horn can do acoustic impedance matching.


Phil Collins can be seen using his hands in front of his mouth to direct the sound to the microphone. Possibly it can be seen on the In my Life - George Martin documentary on YouTube.


How would it sound like to record many musicians gathered near a horn and the other side of the horn to a top,quality dynamic microphone?


A big horn, eg 2 square meters.

How the Doctor Who music was made Πως έγινε η μουσική του Doctor Who

There is a very interesting video on YouTube:


https://m.youtube.com/watch?v=C1Pl83oqGhg


It shows the BBC radiophonic workshop.


It takes you through to the creation of the Dr. Who music sound by sound.


First synthesizer shown is the
Yamaha CS80 that Vangelis is also using:
https://m.youtube.com/watch?v=zoEkyBX7qsg


This from the original Delia Derbyshire tapes?
https://m.youtube.com/watch?v=I-e_TCqb4qQ


Another interesting music again from the BBC radiophonic workshop is Delia Derbyshire playing Bach - Air:
https://m.youtube.com/watch?v=zoEkyBX7qsg


This one showing many Ferrograph tape recorders:
https://m.youtube.com/watch?v=6N1I_03wPEE


This very interesting documentary on Delia Derbyshire born in Coventry who was influenced by the war sounds and meaningful sirenes to revolutionize music:
https://m.youtube.com/watch?v=85SEfawIKXc

A pair of Electro-Voice 635a as binaural 3D microphones

Using possibly the simplest signal path analog recording.


The microphones were held by hand next to each ear, pointing to various directions.


Most directions sounded great, even both mics pointing toward each ear.


So great that while playback the recorder had to be stopped many times to figure out if the ambient sound was happening now or was the one that had been recorded.


It was amazing that what was thought to be real was in fact recorded.


Pleiades filters (just 82mH in parallel with each mic's output) did an excellent job of giving a flat frequency response to listeners brain, by gently compensating exaggerated bass in the signal path. 333mH was also tried being somewhat bass heavy.


Signal path:


Ambience - right channel 635a on right ear - Pleiades 82mH -

                         - SONY TCD5 Pro II - Sennheiser HD580 - ears - brain

Ambience - left channel 635a on left ear - Pleiades 85mH -

How similar are the best front and last end amplifiers.

It is interesting.


Some of the best recordings on our planet are done with an electron tube microphone. An obvious example is CBS recordings done at Columbia 30th street converted church in New York. Ray Conniff for example.


Some of the best reproduction is done by a single ended triode class A power amplifier.


The interesting part is that in producing and reproducing from the brain of the performer to the brain of the listener the closest amplifiers are almost identical.


How similar is the schematic of a Neumann U47 microphone to the schematic of the 300B output stage!


One difference is that the microphone has the output transformer coupled to,the electron tube through a capacitor.


On the Pleiades V6 battery microphone pre preamplifier the output transformer is directly coupled to the electron tube.


The V6 can be connected to a world class dynamic microphone too. So in fact it plays the part of what amplifier world class condenser microphones have inside them as front end. Lefteris Logaridis gave a very important spark by suggesting years ago building a VF14 amplifier based on the schematic of U47.

Μαγικο Σάντουιτς Νο 3

Με δίκη σας ευθύνη.


Ψωμι ολικής φτιαγμένο χωρις λάδι.


Αλειφουμε και τις δυο φέτες με ταχίνι ολικής Κοσμιδη Γαβριλη.


Βάζουμε τσουκνίδες που έχουμε αποξηράνει όσες μέρες χρειάζεται.


Λεπτα κομμένα ωμά μανιτάρια.


Πιπέρι, αλάτι.


Σταφίδες μαύρες, λιγο Γκοτζι Μπέρι, λιγο κανέλα Κευλανης.

Το τραγούδι Νύχτα Στάσου εχει όμορφο κώδικα

Το Νύχτα Στάσου - Νικολοπουλος - Πυθαγορας - Διαμαντη εχει πολυ όμορφο κώδικα.
https://m.youtube.com/watch?v=Wd5W04V35gE
(Τι ωραια που ακούγεται και το echo room στο υπόγειο του στούντιο της Κολουμπια.)


Συνέχεια η μελωδία με το μπαςο δημιουργούν ενδιαφέροντα απροσδόκητα διαστήματα.


Ειναι αυτο που λει ο Ray Conniff σε συνέντευξη του. Μπορεί να παιχτεί με ενα μόνο δάκτυλο στο δεξί και αριστερό και να ακούγεται πολυ ωραια. Όπως στα καλα κομμάτια καθε καλής μουσικής.

Do we have to impedance match the antenna to rf amplifiers?

We do not do this when we want to amplify the faintest signal from a microphone.


We use a step up transformer to feed an electron tube or JFET which have a high input impedance.


We are not interested in maximum power transfer. We are interested in maximum voltage and amplifying this.


Why not use the same principle on RF amplifiers?


Would the Pleiades battery electron tube front end preamplifier make a contribution to space communication?


Would the US Patent 1944574 on positive grid bias which shows that when the slope of grid current with respect to grid voltage curves gets negative we have regeneration, prove important if not already?


If there is life on the Pleiades star cluster would we able to communicate?


It takes about 300 years for a signal from there to arrive to earth.


How would we know at which frequency to tune to?


May we investigate the most efficient wavelength for this kind of communication, and then try to guess what this intelligence would have chosen as a wavelength that we could figure out from universal constants.


For example, we easily see 7 stars from the earth. Another constant is the distance, the speed of light. Could playing with the numbers enable us to find the right wavelength they had in mind aiding us to figure out?

Pleiades Electra one tube headphone amplifier with other tube types?

It would be nice to experiment with other electron tubes too.


Space charge tubes with less power output than 12K5.


Also the possibility of EF183, this time as a power amplifier with a resistor from anode to grid to free electrons as is done on the Pleiades preamplifiers.


A 12SK7 is a good candidate too as with the positive bias grid neutralization it may give a one or two milliamperes even at 12V plate supply through the headphones.

Edwin Armstrong on electron tube positive bias

Some inventors are centuries ahead of their time.

The first 100 years have already passed since Edwin Armstrong, not only inventor of FM radio,  published in 1917 (re edited from 1914) a paper mentioning kindly how the operation of the triode vacuum electron tube is not very well understood...

In modern time (and backwards in time too), it seems technology goes so fast that sometimes details are left behind.

God is in the details, as master composer Johan Sebastian Bach used to mention...

The Armstrong paper is cited at the end of this post.


A small part of it, relevant to the Pleiades V series preamplifiers operating with less than 6 volts anode potential thanks to positive bias grid neutralization, will be copied on the following paragraphs.

As it has been mentioned on euroelectron posts, electron tubes can operate as very sensitive and low noise preamplifiers with very small battery anode voltage (as well as reduced heater voltage although it seems this can be done anyway), when positive bias neutralizes the grid. The first point on the Armstrong's paper is copied below, being the most relevant.

At the time (1917) the word Wing was used instead of Plate or Anode and Audion instead of Triode.

The modern terminology and comments will be given in parenthesis.

So let us hear the master inventor...

(End of the paper's second paragraph...)

The characteristic shows that, starting with the grid and filament at zero potential difference, a negative charge imposed to the grid produces a decrease in the wing (anode) current and a positive charge imparted to the grid produces an increase in the wing (anode) current.

(So far so good, this is what we know too on 2017).

Edwin Armstrong continues...

This is the fundamental action of the audion (triode) when used either as an amplifier or as detector. The reason for this action will appear upon examination of the behavior of the audion of the type shown in Fig.3.

(Before moving on to the very important 3rd paragraph, it seems fit to clarify that on figure 3 is drawn a triode which has 2 anodes, one on the far left of the glass valve envelope and one on the far right).

Edwin Howard Armstrong...

The wings (anodes) of the audion (triode) were placed symmetrically with respect to the filament, but only one grid was employed. (between filament and right plate). It was found that, under similar conditions of filament temperature and voltage of the battery V2 (plate supply battery), a considerably smaller current was obtained between the filament and plate on the side in which the grid was inserted. In both measurements the grid was left entirely free of any connection with the rest of the apparatus. Obviously the grid obstructed the flow of the thermionic current. Investigation showed that this was due to the charge accumulating on the grid when exposed to bombardment by the electrons passing from filament to wing, the electrons pass readily enough into the grid but cannot easily escape from it, and as a consequence of this, negative electricity piles up on the grid. The potential assumed by the grid when exposed to this bombardment may be several volts negative with respect to the negative terminal of the filament, it may be the same as the negative terminal, or it may be positive with respect to the negative terminal, but it will always be negative with respect to the potential of the field in the plane of the grid which would exist if the grid were removed from the bulb. The negative charge on the grid, therefore, impedes the flow of electrons from filament to plate, causing the decrease in wing (plate) current. The placing of a positive charge on the grid from an external source tends to neutralize the negative charge on the grid, thereby permitting an increase in the wing current. The addition of a negative charge to the grid increases the deflection of the electrons and produces a further decrease in the wind current...

So this is the third paragraph of the amazing paper written 100+ years ago.

This is a very helpful and revealing explanation on why the Pleiades preamplifier operates at even less than 6 Volts on the plate when the grid is neutralized from its self assuming negative potential. This is done by connecting a resistor of the order of 4.7MΩ from anode to grid on the Pleiades front end preamplifiers. The electron tube used is the EF183 triode connected.

Armstrong describes that the negative potential is caused by electrons passing from filament to wing (anode).

It was found by accident while experimenting with the Pleiades V6 on breadboard that the grid is negative even without any plate source connected to the apparatus.

At the time of Armstrong there may not have been voltmeters of very high input impedance, so direct true measurement of the grid potential may not had been feasible.

Now it may be argued that Armstrong was experimenting with a tube that had more gas, less evacuated, than modern tubes.

The Pleiades experiments were performed on modern vintage ECC82 and mainly EF183 vacuum electron tubes.

It is striking performing the following experiment. This is by carefully (fuse in series with battery is important for safety), supplying 6.3V only to the cathode heaters while a high input impedance (Z=10MΩ) voltmeter is connected between cathode and grid.

As soon as the cathode starts heating up, a large voltage of millivolt order keeps increasing until the temperature rises to its peak value.

If we then measure grid to cathode current, (we in fact short circuit the grid to the cathode using a micro ammeter), a substantial grid to cathode current is caused by the measuring procedure itself.

So it is observed that just the boiling of electrons out of the cathode can induce this grid (cathode) voltage and current.

The same phenomenon occurs by repeating the same measurements to plate instead of to grid but it is much less pronounced as the plate is much further from the cathode than the grid.

Acknowledgement is due to Hliana for insisting that the grid must be positively biased.

Reference:

Operating Features of the Audion - E. H. Armstrong - Annals N. Y. Acad. Sci. Vol XXVII, pp. 215-243, 2 August, 1917

Pleiades 1 transistor /channel headphone power amplifier

It is the corresponding circuit to the tube (Electra) version and to the JFET version but this time with a bipolar transistor.


The headphone is the collector resistor itself.


So for stereo we just need 2 transistors for the simplest signal path.


One resistor form the collector terminal to the base is for biasing.


Everything is in Class A (electrons flowing all the time even through the headphones themselves).


Germanium transistors sound very nice, is this due to the higher mobility of electrons?


One can experiment with OC series germanium bipolar transistors, OC58, OC71, OC72...


Silicon transistors should sound very nice too.


Sound is big, detailed and amazing. Deep bass!


We must protect our ears when listening through headphones, levels must be low.


Reference:


Transistor Audio Amplifier Manual - Clive Sinclair - Bernard's Radio Manuals, Bernards Publishers LTD, London, first published 1962 -reprinted November 1977 - pages 5-7

Η ωμή Τσουκνίδα

Με δίκη σας ευθύνη.


Αν κόψουμε με γάντια καθαρές τσουκνίδες και τις αφήσουμε σε ενα πιάτο για 2 μέρες...


Και φάμε στην αρχή πολυ προσεκτικά...


Έχουν γεύση σαν να τρώει κανεις ψάρι.


Έχουν ω λιπαρά;


Υπάρχει απίστευτη Ιταλικη συνταγή με ομελέτα και τσουκνίδα.


Εκεί μοιάζει η υφή και η γεύση σαν ροκφόρ.