Άλμπερτ Κετεντζιάν, Albert Ketentzian, the Master Piano Tuner

       Ο Άλμπερτ Κετεντζιάν είναι ο μόνος που έχω γνωρίσει με εξαίρεση τον Μίμη Πλέσσα που διδάσκει ότι η μουσική οκτάβα είναι μεγαλύτερη απο την μαθηματική για να ακουστεί όμορφα στον ακροατή.

       Αυτό αναφέρεται μόνο στα καλύτερα βιβλία ακουστικής όπως αυτό του ιδρυτή του εργαστηρίου ψυχοφυσικής στο πανεπιστήμιο Χάρβαρντ, Σ. Στήβενς [1]. Η μετάφραση του βιβλίου Ήχος και Ακοή στα Ελληνικά έχει γίνει από τον Δρ. Εμμ. Τιερρή, πρώην διευθυντή χειρουργικής στον Ερυθρό Σταυρό και είχα την τύχη να έχω τον γιό του Γιάννη διπλανό στην Λεόντειο.

       Όταν το 1993 αποφoiτησα απο το Αγγλικό Πανεπηστήμιο Warwick με τίτλο B. Eng. Engineering Electronics, o Άλμπερτ που ήδη τον γνώριζα με ξάφνιαζε με θέματα όπως το παραπάνω και δεν μπορούσα να πιστέψω τι μου έλεγε.

       Μου τα αποδείκνυε όμως στο πιάνο και μετά με ηλεκτονική μέτρηση. Έψαξα και μόνος και ακόμα κάνω και από τότε έγινε δασκαλός μου και στην ηλεκτπονική αφού γενήθηκε στον Καναδά και ήρθε σε επαφή με πλήθος synthesizers και ενισχυτές που από τότε ήταν στην αιχμή της μουσικής παραγωγής.

       Πάντα με την ακούραστη γυναίκα του Μαρίνα μου συμπεριφέρονταν με αγάπη και σεβασμό και είναι τόσες οι όμορφες συζητήσεις στην αίθρια υποδοχή του εργαστηρίου στην Βάρνης, βράδυ καθισμένοι κάτω απο όμορφα δέντρα. Σχεδόν ακούραστα τελείωνε ο Άλμπερτ την εργασία για να συζητήσουμε πάλι για τα ίδια με καινόυργια οπτική γωνία. Λίγα απο τα τελαιταία έτη χαθήκαμε αλλά ερχόμενοι πάλι κοντά διαπίστωσα καινούρια ανακαίνιση στη μονοκατοικία, εσωτερικά και εξωτερικά. Μια πανέμορφη μονοκατοικία απο τις ελάχιστές πια στην Νέα Σμύρνη που ασφηκτικά δεν θέλει άλλη μια πολυκατοικία. Είναι ωραίο να υπάρχει μια αναφορά στο παρελθόν,  έμπνευση στο μέλλον και για τις επόμενες γενιές σε μια Ευρωπαική πια Ελλάδα που σέβεται την ποιοτητα ζωής, τον άνθρωπο και την ιστορική πολιτισμική κληρονομιά.

       Στο εργαστήριο μουσικής της Βάρνης και στις συναυλίες για τον συντονισμό πιάνου που με έπαιρνε μαζί του γνώρισα από κοντά τους σημαντικούς καλιτέχνες της μουσικής δισκογραφίας και του θεάτρου. 

       Το εργαστήριο αυτό βοήθησε και μένα αφού ο Άλμπερτ απλόχερα πραγματοποιούσε οποιαδήποτε ιδέα μου για να δούμε αν θα λειτουργήει ή όχι. 

      Είμαι ευνόμων στον Άλμπερτ που απο τότε που πρωτοσυντόνησε το πιάνο μου και για 30 έτη στο εργασήριο του με την θέληση μας μου δείχνει τον μαγικό κόσμο της μουσικής και της ηλεκτρονικής.

       Συνεχίζει στο εργαστήριο του ακάθεκτος και η γνώση και η μετριοφροσύνη του που χαραχτηρίζουν κάθε αξιοπρεπή ανθρωπο τον κάνουν να είναι σε πρώτη ζήτηση όταν έρχεται μεγάλος καλιτέχνης απο το εξωτερικό σε συναυλία, όπως αυτό το καλοκαίρι του 2026 στην Πλατεία Νερού με το πιάνο του Nick Cave επιμελημένα από την αρχή της μέρας συντονισμένο απο τον Άλμπερτ.

       Στα χνάρια του ο γιός της Μαρίνας και του Άλμερτ, Αλέξης που ανεξάρτητα στον επάνω όροφο έχει φτιάξει στούντιο ηχογραφησης. τον βλέπω από πριν το 2000 να το βελτιώνει συνεχως. Και η κόρη τους Άννα να είναι ανεξάρτητη και διμουργική στο Λονδίνο.

       Τους ευχαριστώ πολύ που κάνουν στην πόλη που συνίδρυσε ο παπούς μου Γιώργος Τσακίρης απο την Σμύρνη να αισθάνομαι ακόμα πιο άνετα. Και να είμαστε λίγο πιό περύφανοι για την Νέα Σμύρνη.

       Η μουσική όμως λειτουργεί στην ψυχή μας με την ακρόαση έτσι ας ακουστεί για παράδειγμα το Λιμάνι του Γιώργου Ανδρέου ερμηνία Μουτσάτσου με τον χαρακτηριστικό ήχο του ακορντεόν από τον δεξιοτέχνη Ηρακλή Βαβάτσικα, πελάτη από τότε του Άλμπερτ στο εργαστήριο της Βάρνης στην συντήριση και τον συγκερασμό.    

Αναφορά [1] Ήχος και Ακόή - Εγκυκλοπαίδια Time, Life

  

Music and Electronics, molecules and electrons

 At your risk.

Music deals with vibrating molecules. for example of the metal piano string, or the vibrating molecules of air which will also hit the ear drum of the listener to create the sensation of hearing in the listener's mind.

Electronics deal with the corresponding vibration of electrons. For example inside the copper wire of a cable which carries the music of a symphony or a beautiful song.

A microphone converts the vibration of air molecules to a corresponding vibration of electrons in the cable at the output of the microphone. The microphone preamplifier will magnify or amplify these vibrations.

The cause of making the air molecules to vibrate in turn travels at the speed of sound in air, the speed of sound in air. The cause of making the electron vibrate in turn inside a wire travels at the speed of light in the metal of this wire. The speed of the light or electromagnetic wave in this metal.

It would seem correct to assume that a perfect sound system would convert exact replicas of the molecule vibration to the electron vibration.

More than often this is not true especially in popular music where the sound reproduction is louder than the moment a singer sings to record.

A reason for this is that the sensitivity of the human mind to frequency is also a function of intensity. For example for soft sounds a bass guitar needs to be as much a s a million times, that is 60db more powerful than a flute (mid range note) in order to sound as loud.

But when higher intensity is involved the sensitivity of the listener's mind to bass frequency becomes much closer to the sensitivity to mid frequencies for a similar sensation of loudness.

The curves that describe this phenomenon are called Equal Loudness Curves.

Due to the fact that the frequency response curve of the human hearing mechanism depends on intensity it may be trivial to assume that for perfect recording and reproduction we need flat frequency response from microphone of singer to the loudspeaker of listener.   

It is more appropriate to consider flat frequency response from record producer mind to the listener's mind.

For example a singer reproduced at higher level than while recording will sound bass heavy.

In addition the frequency spectrum of a singing voice depends on effort when singing. For example when a singer sings softly the bandwidth of the voice is much higher with an increase in bass and high frequency content than when singing loud where most energy is concentrated on mid frequencies.

This would make a softly sung melody sound even more bass heavy when reproduced at a higher level.

To make such a situation sound correct to the listener's mind is not only a great work of engineering but also a great work of art.

For example Suzan - Leonard Cohen

(A loudspeaker or headphones convert electron vibration back to air molecule vibration so that we can listen to the beautifully made example below):

Further Reading:

Sound and Hearing - S.S Stevens, F. Warshofsky - Time Life Encyclopedia

Sound Picture Recording and Reproduction Characteristics - D.P. Lowe, K. F. Morgan - Journal of the society of motion picture engineers

Elements of Sound Recording - Frayne, Wolfe

https://en.wikipedia.org/wiki/Equal-loudness_contour

Additions to The Melody Book

 At your risk.

It is so instructive how the singer raises the pitch of his voice as a note build up so that it sounds correct to the listeners mind.

I Follow Rivers - Lykee Li chorus harmony (chords)

 At your risk.

They can be clearly heard at 1:50.

The key is A minor, that is the first bass note is A. In the key of A minor all notes are natural, the white keys of a piano keyboard.

At chorus bass becomes F so using the simple rule 1 3 5 or 1 3 5 7 the chord is F A C or F A C E so the bass code is F or F7.

Then the harmony is G7 that is G B D F, using the Principle of Least Change in Music since the previous chords is F A C E we can play F G B D (the same trick used by Bach on the 1st prelude in C Magor from the Well Tempered Clavier for example at 1:02-1:04. The code is different but you can see the similarity of keeping the bass the same (pedal bass) in order to get from one chord to the next with the least possible note changes.

Then bass becomes A so harmony is using the simple harmonic triad code 1 3 5, that is A C E.

Then bass becomes a step down that is G. If we play harmonic code that is G B D it sounds trivial and wrong as we have parallel fifths (as Bach calls it the error in music). So again using using the Principle of Least Change in Music the composer plays G B E (E is kept from the previous chords), that is the code is G6. WIth the 6th or 7th or 9th (with respect to bass) as Bach says in his manual we add the 3rd/ So we have G B E which sounds fantastic.

It is the same chord progression as the first 2 chords of Old and Wise _ Alan Parsons Project:

So the 4 chords at the chorus are:

F A C E 

F G B D

A C E

G B E

If these are played on the left hand at the middle the keyboard of a well tuned piano and we the right hand the melody, it should sound very nice.

This is how it will be scored on The Melody Book.

Further reading:

Instructions for playing thorough bass by her Johann Sebastian Bach for his scholars in music

(It can be found at the appendix of Bach's Biography by Spita)

 

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Sennheiser HD 580

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Posts

Sennheiser HD 580

 At your risk.

https://diyaudioheaven.wordpress.com/measurements/brands-s-se/hd580-precision/

Sustain piano pedal and change of key from E minor to B minor

 At your risk.

The Mic(s) and the Piano

 At your risk.

Just a Microphone Cartridge, update

 At your risk.

The microphone cartridge mentioned in the previous before previous post is more probably a Shallin D-26A. A heavy cartridge compared to similar looking ones. It is whitish color with a black plastic protective mesh. Soldering connections are on the underside than at the side.

Passive electronic components

 At your risk. Any battery must be connected to a suitable fuse to avoid burn or fire hazard.

A wire is a highway of electrons. In a conductor such as copper at room temperature some outer electrons have enough energy to leave the atom. So we have in a cable a sea of electrons.

On direct current, a stream in one direction the electrons may move quite slowly at say 5cm per second.

Why would then a light bulb connected to a 10 meter cable light immediately by connecting the other side of the cable to a battery?

The electrons next to the bulb that will almost immediately start moving.

The almost immediate is because light needs such a little time to travel 10m.

It is the electromagnetic wave that causes the electrons to move.

So they may move in some situations slowly but their cause of movement moves very fast.

Resistors impede the flow of electric current by electrons colliding with atoms. they lose energy and this energy is converted to heat. Sometimes we use resistors to cook our food in the kitchen. 

Capacitors store electrons. They store energy in the form of electric field.

Inductors tend to keep the flow of electrons constant. Inductance behaves like a mass. If a mass is stationary it was to keep being stationary and reacts to change in it kinetic condition. If a mass is moving it reacts in trying to stopping it, accelerating it or decelerating it. Try stopping a train or a ship (large mass equivalent to large inductance). By stopping abruptly a mass for example by collision great forces are created. In a similar way a great voltage is created at the terminals of an inductor if we try to stop the current by disconnecting the circuit so we must never touch the terminals of an inductor. The spark we see is possibly by ionisation of the air by the large voltage.

 A capacitor in series will cut bass frequencies

An inductor in series will cut high frequencies.

A capacitor in parallel will cut high frequencies.

An inductor in parallel will cut bass frequencies.

Further reading:

Electronics, a Systems Approach - Neil Storey

 

Just the microphone cartridge used as a microphone

 At your risk.

Today one inexpensive moving coil cartridge was tested. Its name may be Shallin D-26B.

The voice coil DC resistance was measured about 600 ohms.

It was then given AC voltage rather than taking from it by connecting it to the headphone output of the Sony CD Walkman usually used. So it was used as headphones. The sound quality was very nice. There was bass and white balanced bass, mid and high frequency content.

Compared to the Sennheiser HD 580, the HD 580 had more extended bass, treble, and less mid range but the sound quality from the mic cartridge used as headphones was possibly the closest to the HD 580 from many headphones expensive or inexpensive lying around the Pleiades lab.

Then it was used as microphone.

Signal path:

singing male voice - indoors (bedrrom0 or outdoors (balcony) - Shallin MC cartridge without a mic housing ie on its own at 24in from singer's nose - SONY TC-D5 PRO II - Sennheiser HD 580

The sound quality so surprisingly nice, without the boxy sound associated with many mics inside their housing. 

The cartridge on its own responds somewhat close to figure of eight.

One of the reasons for the natural sound could be the fact that there are no obstacles close to it like a microphone housing distorting the sound field.

Compared to the Shure Unidyne B Mexico, the Shure had more extended high frequency but the single mic cartridge sounded more warm or natural. How would Unidyne B sound without the mic housing?

How would 2 Shallin cartridges sound each back side placed at each ear for (3D) binaural recording.

How would 2 sound as stereo headphones?

\

Would it be possible to create a stereo mic or headphones using just 2 such cartridges for both which could be rotated so that at playback diaphragm faces the ear, at recording diaphragm faces in the opposite direction.

There was handling noise when holding the cartridge by hand but the problem was much improved by suspending the cartridge by the 2 thin wires soldered to it.

How would 2 of them sound at stereo, at 90 degrees to each other and very close?

Why is it so?

 At your risk.

Electric field, Magnetic field, Electromagnetic waves

 At your risk.

1. Stationary charges create an electric field.

For example an electrically charged pen by rubbing it to wool, attracts small pieces of paper.

2. Moving charges create a magnetic field.

For example a direct current passing through a wire near a magnetic compass will deflect it.

3 Accelerating charges create an electromagnetic field

For example vibrating electrons inside the radio transmitter's antenna will radiate electromagnetic waves. When they reach the receiving antenna its electrons will vibrate in a similar way, so information is received.

When there is no music broadcast the electrons vibrate at the radio station's frequency. When music is playing the carrier wave is modulated in amplitude (AM for amplitude modulation) or in frequency (FM for frequency modulation) by the music signal.

   

Electron Lab

 At your risk.

An electronic construction game with springs used for connecting the electronic components.

It was started been made up today by buying a white cardboard box, size of a UHF VHF Manual -Jessop.

An a bit smaller smaller on one side but thicker box lid was inserted up side down. On it will be mounted 10 springs.

The idea is to create a circuit with the exact layout of the schematic.

This is to be given tomorrow to a boy and his mother visiting Athens from Bulgaria. Hopefully the bring boy will compete it.

It it designed for hopefully easily making a single transistor power amplifier in class A.

Components included or considered.

2N3053 transistor

Various precision resistors.

9 Volt battery clip

Oval speaker

Various color (tiger strip) capacitors, also blue or orange Philips capacitors

A small oval loudspeaker drive unit

Belclere output transformer

Updates to the Pleiades DL94 single electron tube battery powered audio power amplifier operating in class A1

 

At your risk. Lethal voltage present.

Five rectangular holes have been created by a jewelers saw for housing five 2 x 9V batteries for a Vb of 90 volts. 

All 5 Bulgin battery holders will be at the back of the diecast aluminum box. Then the output transformers then each DL94 for each channel and then the step up input transformer for each electron tube.

In the front will be a Bulgin holder for 2 AA batteries for the direct heated cathode voltahe Va, and a battery holder of AA size for the -6V Vc bias.

This amplifier is using no resistors or capacitors, like the original Harold Arnold 20's patent of the use of thermionic currents...

Please visit older posts for more details.

 

Other single transistor amplifier circuits

 

At your risk. Please take all safety precautions. A suitable fuse always in series with a battery to prevent burn injury or fire hazard. in this case a suitable fuse (200mA?) will prevent your speaker from blowing in case of thermal runaway etc. 

These amplifiers are similar to the Pleiades 2N3055. Now usually an air gaped output transformer is used but the second schematic is what was simplified from the book Amplifiers by Jones. There is also a very interesting book Transistor Amplifiers for the home constructor by SIr Clive Sinclair who is also behind the famous ZX Spectrum home computer.  

One of  first listening experience with such an amplifier was with just a 2N3055 fed by the song Is it a Crime - SADE from CD, the amp feeding a SONY APM speaker with just a low cut capacitor from the paper cone tweeter. Jaw drop mode. When Vicky first heard this amplifier on Constant Craving - K.D. Lang she could not believe this fabulous sound was coming from this small mess of wires on the floor and one transistor cooled by a French wrench. She still calls this amp the French wrench amplifier.

With just one amplifying stage here is only one set of distortion products and you may be in the league of the Neumann U47 with its amplifier of one VF14 electron tube. 

Marios from the photocopy shop told me that this great sounding PC USB powered Fujitsu Siemens speakers from the 90's may have just one transistor inside for each speaker.

By doing a search on google for "90's usb powered pc speakers one transistor amplifier schematic"...

https://forum.allaboutcircuits.com/threads/simple-pc-audio-amplifier-circuit.109732/

Life is good!

Why does pitch change with change of intensity?

 At your risk.

For example playing a 440Hz louder gives the perception of a lower pitch.

Why?

Not clear to me.

A piano can convert frequency to distance. For example by pressing the right pedal we leave all strings undamped. Then then if we whistle for example, the higher the frequency the more to the right strings are vibrated by resonance.

The basilar membrane converts frequency to length. 

Is it a nature's way of protecting the ear? Pitch change by stimulus intensity preventing the same hair cells being fired  along the length of the basilar membrane?

Is the change of position at the basilar membrane due to some non linearity in amplitude response. creating a DC offset?

Similar to demodulation of AM signals by the rectification effect of a diode?

(Side chain signal of a compressor created by diode rectification? Does the movement of the 3 tiny bones in the middle ear play a nonlinearity part too?)

Similar to DC bias change of single ended amplifiers with cathode current bias, RC (cathode resistor).

Similar to expansion in solids by temperature increase, there is nonlinearity in the vibration of molecules, the displacement to the right is higher that the displacement to the left.

Handbook for Acoustic Ecology

 At your risk.

https://www.sfu.ca/sonic-studio-webdav/cmns/Handbook/

Pitch

 At your risk.

https://www.sfu.ca/sonic-studio-webdav/cmns/Handbook/Pitch.html

Pitch Change of tone of 440Hz by changing the intensity

 At your risk. Please keep volume down to protect your ears especially if using headphones.

By comparing soft volume to higher volume, the higher volume sounds to me lower in pitch.

As loudness tends to zero pitch becomes maximum.

How about you?

The fact that i hear a lower pitch makes me sing along a note of lower pitch. 

This (even if it is a small difference) is important because it makes a singing note sound really bad and out of context with the music or backing track. For example annoying beats could be created.

Listening carefully to good singers, the very good world class ones, it can be heard that they too begin almost any note flat (below correct pitch) but then raise the pitch while the note sustains until it sounds correct. I tried this trick and my singing is so much better and enjoyable. I try to correct almost every note.

Psychoacoustics - Pitch Perception

 At your risk.

Vocal Exercise from real well known beautiful Song melodies

 At your risk.

For example closed lips 3:36 to 3:42 on Such a Shame - Talk Talk

Instructor can play figured bass E, then E6 then D, that is E G B, E G C, D #F A, while student can sing the beautiful melody with the nice glissando.

Then transposing a semitone up etc.

Such a Shame - Talk Talk

 

Update on the Pleiades 3 K117 battery powered JFET phono preamplifier

 At your risk.

If any of the two 9V batteries is discharged the preamplifier goes into motorboating oscillation.

Possible cause the increased internal resistance (ie output impedance) of the battery creates voltage drop at the first stage from the current drain of the other stages. this is equivalent to an input signal or really positive feedback signal. If series resistors and then capacitors to ground for each stage were used this could solve or reduce the effect but it is decided not to use any of them.

The battery or batteries should be replaced anyway and this is a sure sign to do so.

As a remix of Such a Shame - Talk Talk was being reproduced suddenly the beat was modulated in amplitude by this very low frequency. It was thought as a production effect and may be used as such. A very interesting stereo tremolo effect. The subsonic frequency may damage equipment or ears so please keep the volume down. If the volume is already up before the batteries are exhausted it can be dangerous.

 

The simple melody Love on previous post can also be called All My Love

Why are some songs often played on the radio, the vocal pitch increase trick for almost each note

 

At your risk.

i have the impression that a good singer may be doing it consciously. Now that i know it i can hear it if i concentrate on the part of each note after the attack which for some reason may be wrong (flat ie below correct pitch) even for the best singers. Is it how our mind works?

What ever the reason if we concentrate on correcting the poor note the feedback mechanism we create gets it right by subtle glissando. Cybernetics in singing. 

For example the first "me" at 0:20, in phonetics notation, mi: or mii the second i is clearly higher so that the singer and listener's mind is happy.

Examples are everywhere on radio but these 2 were heard today on Rock FM in Athens, Hellas.

Another example, i can not remember on which FM radio station it was heard a few days ago:

i heard about this trick from a serious looking intelligent person while i was doing my military service, long time ago. i could not really believe what he was saying. It took me many years to digest and rediscover.

It surely helps me enjoying singing.

Of course there are many more elements that can make a song liked, please see for example Hit Song Ingredients - euroelectron.

Love, a simple melody with nice chords in F minor key

 At your risk.

F minor is a very beautiful sounding key. For example:

Almost accidentally both pay buttons were pressed and a mush up was created.

The simple melody of Love was somehow inside me perhaps after listening to the radio, or after feeling something for sometime. By playing on the Pleyel upright piano some of the beautiful chords defined by the key of F minor were asked for to be used. The chord defined by bass bD, bass F, bE, bass bB.

The code (Bach's figured bass notation) of the chords is bD7, F, bE6, bB79.

So together with the melody.

-   -   F   -                         D7

A  -   B  C

o   -   -   -                          F

-   -   C  G(down)

o   -   -   -                           E6

-   -   C   B

o   -   -   -                            B7 or B9

-   -   -   - 

repeat

please remember the key signature of F minor, all A, B, D, E are flat so for example bD7 is played bass bD with chord F bA C ie bDmaj7. ANd of cource the melody notes are F bA bB C....

The symbol o means that the note carries on.

The symbol - means pause of 1/8. So each chord lasts 8 beats of 1/8.

The title on the cassette demo is love with another 2 words, not currently remembered.

 

  

A battery powered high quality sound reproduction system from phono cartridge to loudspeaker

At your risk. Please take all safety precautions. A battery must be connected in series with a suitable fuse to avoid skin burb in case metal jewelry is worn or avoiding fire hazard.

This system combines previously described Pleiades amplifiers.

It was put up together today for the first time with phono channel out of phase connection corrected and with the RIAA cooking corrections in order to correct overal preamplifier response as described on previous posts.

Preamplifier and power amplifier are operation in class A (electrons flowing all the time, even when there is no music playing).

Total number of transistors used for each channel is 4, 3 K117 JFETS for the preamp operating in low gain with local feedback (source resistors unbypassed) and one 2N3053 on very small heatsink for the power amplifier with zero negative feedback.

Both the phono preamplifier and power amplifier have an output transformer. The power amplifier has a relatively small ferite output transformer with air gap separating the 2 E sections as there is DC current flowing in the primary. Toilet paper is used for the air gap and Siemens Es anre secured together with metal clamps fastened with bolts and nuts.

The DUAL CS-627Q direct drive turntable is battery operated too with same voltage as the power amplifier. 24V from two 1.2Ah powering both turntable and stereo power amplifier.

The hono preamplifier is powered by two 9V batteries.

Power consumption is very low, current consimption is about 20mA for the stereo power amplifier now than the ambient temperature is high, 14mA in the winter. The turntable consumes about 100mA. the phono stereo preamplifier about 2 mA. So total power consumption is somewhat more than 2 Watts.

Power output should be of the order of 100mW yet it sounds surprisingly loud with huge bandwidth and no need was found in today's listening tests for higher volume in a small bedroom with speakers at about 2m or less from listening position.

Signal path:

CD or vinyl records - Sony CD Walkman D-EJ758CK or Dual CS-627Q with original Ortofon cartridge and new stylus - Pleiades 3 K117 phono preamplifier - Pleiades 2N3053 power amplifier - Celestion Ditton 150 loudspeakers - small room with 3 Pleiades membrane (bitumen felt) bass absorbers inside white painting stretched canvas frames of 3 different dimenssions 

CD used is The Year of the Cat - Al Stewart

Records used: Only Love LP - Nana Mouskouri

                        Brothers in Arms LP- Dire Straits

                        One Day in your Life 7" single - Michael Jackson

                        Take a Look - Natalie Cole double LP

The sound quality was amazing, breathtaking with huge bass, smooth mid and very extended treble about 3 more octaves than listening to YouTube, at least one more octave than listening to CD. About at least one more octave that listeningto other CD systems even very high quality ones yet without the harshness. 

Anbience sounded amazing.

And strings did not sound harsh at any time. This is possibly due to the fact that the passive RIAA filter comes immediately after the low gain 1st stage. Therefore clipping of the extreme content of high frequency due to preemphasis on records is avoided, see previous posts on the Pleiades 3 K117 design.

The whole system was exremely quiet no noise or hiss heard at any time even when volume control is at max and no record is playing.

Very impressive is how exteded treble sounded with no harshness, the deep bass and smooth liquid midrange.

The power amplifier is just one transistor for each channel.

   

Equal Loudness Curves can be translated as Καμπύλες Ισης Ακουστότητας

Ωκεανός - Ναντια Διολιντζή Lyrics, Γιωργος Τσακίρης music, Ocean - Nandia Diolingi, George Chakiris, elements of the song

In B minor.

Bossa nova.

Step down bass.

Bass Code (Bach figured bass notation):

B

A6

G7

F7

modulation to E Dorian

E

E46

Example melody with lyrics:

-   B   D   -            στα - γο           chords   (harmony) B D #F

B  -     -    A           να      πεύ-                    

o   B   ο    -            τω                                                  A  #C #F       

-    -     -    E          βυ-

F   D   B    ο           θί - ζο - μαι                                   G B D #F

-    -     -    Α           στον

-    Β    Β   Β          ω-κε-α                                          #F A #C E

Α    ο    Β   ο          νό σου

.   .    .

-   -   B   A              κρά -τα                                           E G B

B  -   -    A

o  o   B   o                                                                     E A #C

A simple MOSFET power amplifier with just a 12V battery, a potentiometer and resistor for bias, an input coupling capacitor and no output transformer

 

At your risk. It may blow your spekaer if  a protective fuse is not connected in series etc.

Please see previous post on Pleiades K951 amplfier with speaker connected directly to the drain of the MOSFET.

Update on Pleiades K951single MOSFET zero feedback single ended power amplifier

 

At your risk.

Today the bifilar 1:1 output transformer was disconnected from drain and connected to the source. This was done fairly quickly as all connections are done with Wago snap terminal connectors.

Source follwer configuration worked with change with readjustment of bias from the 50K potentiometer in series with 47K  but sensitivity was low as there is no voltage gain.

Signal path:

CD - SONY CD Walkman - Pleiades K951 as source follwer - Marantz Imperial 5C

So power suppling the speaker was low.

The amplifier was remodified to drain follower.

Then the output transformer was removed and the AKAI SR H-44 speaker connected directly to drain instead of a load resistor. This should not blow the speaker if drain currect (which now passes through the voice coil) is kept by suitable bias to up to say 300mA. It worked and sounded nice, but less loud than when using the output transformer due to loss of efficiency.

Betasilk or Betaplast etc

 

At your risk. This is not a medical or dermatologist advice. Betadine cream is not suitable for persons with thyroid problem.

Combining 2 products together to create a new product. 

Hansaplast with Betadine cream.

Hansaplast moistened with Betadine cream applied on skin spots may vanish the spot if applied overnight(s) or during the day. 

Betadine cream softens the spot until it breaks, it disinfects and the Hansaplast tisue absorbs.

Thsi idea comes from adapting my dermatolosgist Yiannis Peros' advice when I had a serious skin infection.

 

Merino Wool t-shirts

At your risk.

One of the best thing bought this year. Black long sleeved.

They are 3 times more expensive than cotton but they last at least 3 times more.

Minerva brand.

They keep you warm in the winter, dry on both seasons.

When the is heavy air conditioning in the summer, you are saved as you are dry before entering the air conditioned environment and you don't feel cold.

Dryness in the key.

And they feel compatible with one's skin.

Πολυκυκλωματιστής 501-Β, electronic construction game Polykyklomatic 501-B

At your risk.

Educational Electronics Laboratory.

It is made in a box similar to Monopoly.

70's, 80's game. 

Springs are used to secure contact to electronic components.

The amplifier does not have an output transformer.

The germanium transistor is directly coupled to the loudspeaker.

Everything operated on a 9V battery.

C1 100nF

C2 2nF

C3 220uF 10V

C4 1.8nF?

C5 40uF 16V

speaker Sanyo PAN  Q GH 8ohm 0.3W

potentiometer: 8.8KOhm

lamp: 14ohm when cold

3 Germanium Transistors, using the diode setting of a digital multimeter they measure:

T1, 9H: BE 0.13V, BC 0.123V

T2, 9o: BE 0.4V, BC 0.142V

T3 7c: BE 0.125V, BC 0.111V

By examining the schematics and internal connections below the springs, the amplifier output stage seems to be an emitter follower capacitor coupled (C3) to the speaker

I fondly remember this game. It gave the opportunity to make my first amplifier. I did not know whether it worked. I did not know how to test it. All I could hear was a click in the small speaker and I thought I had done something wrong.

It all came to life when the radio AM tuner from the bigger game 1002 (102 constructions) was connected and radio could be heard around the room with good quality.

 

Pleiades K951 single N channel MOSFET zero feedback audio power amplifier in class A1

At your risk. Take all safety precautions. A suitable fuse must be in serries with any battery for injury or fire hazard protection.

Today the 2SK951 MOSFET was placed on the big heatsink.

Vb=12V. Output transformer bifilar 1:1 with air gap.

Signal path:

music on CD - SONY D-EJ758CK CD Walkman line out - Pleiades K951 - Marantz Imperial 5-G

It sounded not loud, and when the 1K pot was near maximum the sound started to fade out.

Fortunately before abandoning, on a quick decisive move the Wago connector was opened and the signal was sent bypassing the volume pot directly to the gate terminal through the 560K Philips orange coupling capacitor.

Sound became big and loud indicating a broken potentiometer.

The amplifier sounds very nice with deep bass and extended treble, smooth midrange. Some overload at peaks as the full signal is feeding the gate without attenuation.

Id is 500mA at Vd 12V. So power dissipation 6W. Possible power output 3 Watts?

It seems a suitable MOSFET can do the trick without the need of a step up input transformer.

But the electron tube Pleiades DL94 seems to sound better.

Thanks to Vasilis encouragement the Pleiades single transistor amplifier experiments were not abandoned

At your risk.

After so many failed experiments today the power is ten times what it was last year. About 3 Watts? 

So according to S.S. Stevens law loudness is double.

 

Humans Are Idiots and I Am a Very Good Specimen

 

Can diabetes be prevented or even reversed by eating whole grain food instead of products made with white flour, sweeteners etc

 

At your risk.

This is not a medical or nutritionist advice.

For example by eating whole grain tahini?

Advantages of Electron Tubes (Electronic Valves), (Vacuum Tubes) in audio amplifiers

 At your risk.

1. They are cute.

2. Some of them can glow nicely in the dark, orange or blue.

3. They are small size and low mass as no big and heavy heatsink is needed for an amplifier operating in class A (electrons flowing all the time)

4. They are very low noise. So low noise that you don't hear any hiss on Sinatra voice recorded with a Telefunken U47 microphone having a VF14 electron tube inside it. The noise performance of a whole system is dictated by the first stage. Also Harry Olson chose an electron tube instead of a JFET on his experiment on measuring  the thermal agitation noise of molecules with a ribbon microphone inside an evacuated chamber.

5. They sound great. We know that for more than a hundred years.

6. Triodes are so far the most linear electronic amplifying devices without any feedback or its side effects.

7. They are perhaps the most compact and easy way to experiment with electrons themselves and what they can do in a small glass evacuated envelope.

8. They do not need air blowing fans. They radiate heat effectively as the anode can be at a very high temperature without destruction of the device.

9. They cannot be so small that we can place millions of them in a small area and then wonder why do we waste energy.

10 They have high output impedance forcing us to use an output transformer, possibly the greatest sounding and most linear passive device ever made. Dozens of microphone, console, reel to reel tape recorder, signal transformers on our favorite sounding records.

11 They teach us to be careful with electricity which can be dangerous. For example by applying the military practice of one hand inside the back pocket so that touching circuits with both hands in avoided.

12 They teach us to be careful in handling electronic devices.

13 They can amplify straight line frequency response from DC to Megahertz and much more as they have small input capacitance and no heatsink which can be a high output capacitance.

14 They can operate at very high but also at very small voltage if the inherent negative grid bias by the electron cloud near the cathode is compensated by a few Megohms resistor from low voltage anode to grid.

The Pleiades single Darlington BD650 power amplifier in class A supplied by 12V sounds very nice

 At your risk.

Update to Pleiades IRFS450 zero feedback single ended power amplifier with air gap output transformer

 At your risk.

Today a freshly charged 1.2Ah 12V battery was connected. Still using the 1:1 output transformer.

Playing the song Blue Velvet the sound was not impressive. As if the amp has reduced gain at small signals and increased gain at large ones. Is this because the operating point is at a current less than 500mA?

Back to the Pleiades single Darlington BD650 with approximately 3:1 output transformer the sound is phenomenally better with so deep bass, bandwidth.

Brothers in Arms - Dire Straits

 

Update to the Pleiades IRFS450 single MOSFET zero feedback power amplifier in class A operation

At your risk. Please take all safety precautions. A suitable fuse must be in series with a battery for injury or fire hazard protection. 

It is almost one MOSFET, an output transformer and gate biasing arrangment.

Today the cute little IRFS450 MOSFET was mounted on a big black anodised aluminium heatsink about 20 times the area of the transistor itself.

Vb is 12V from a 1.2Ah lead acid battery.

Bias is created as follows. From Vb a potential devider is created with one 47Kohm resistor in series with a multi turn 50Kohm potentiometer. Bias is taken from the wiper of the potentiomer and directly applied to gate.

1st test with a 100 ohm load resistor. Vd=7V at Vg=3.3V

2nd test with 6R8 load resistor. Vd=7V when Vg=3.3V

3rd test with only the primary of the Pleiades 1:1 output transformer with air gap, connected between Vb and drain. The primary DC resistance is 2.4ohms. For given conditions best sound is when Vg=3.7V.

Signal path:

Brothers is Arms - Dire Straits on vintage compilation CD - SONY D-EJ758CK CD Walkman line out - Pleiades IRFS450 - Marantz Imperial 5-G

Yes it worked and sounded surprisingly nice.

Initaly there was some clipping distortion as no volume control had been connected. A potentiometer should always be connected for ear protection anyway. The nearest potentiometr found on the table was a 220Kohms. It worked attenuating the output of the CD walkman but once there was attenuation there was severe treble cut. Possibly form high impedance feeding the high? gate capacitance.

When poentiometer (which must be changed soon to a low K value) was at max, at the begining of the song which is quiet the sound is phenomenal, bright, clear with great bandwidth.

As bias is increased sound is not getting better. There seems to be voltage drop at the small battery.

Heat sink is running hot.

Things look promising. Thank to Panos for giving me the inspiration to try a MOSFET by letting me know of the Suzan Parker zero feedback schematic.

In Music the bass line or melody line are both one note at the time

 At your risk.

For example listening:

On exaple below Melody is the top line, Bass the bottom line:

Anothe bass example, bass going in octaves:

Another example:

Classic example of just voice and bass at 0:38, True - Spandau Ballet:

The rainbow makes you feel happy

 At your risk.

It can be seen while watering with a hose thirsty plants on a field, while sun rays are scattered by the water expanding beam.

The only Product of Art is Hapiness

 At your risk.

Paraphrasing the quote by Brian Eno.

Beginning of the Pleiades IRFS450 single MOSFET audio power amplifier in class A operation (electrons flowing all the time)

 At your risk.

Possibly the first time experimenting with a MOSFET in the Pleiades lab.

I think it is same to IRF450 on a different case.

It is placed on a relatively small heat sink.

In order to check the MOSFET is in order, a digital mulimeter was used at resistance measurmnet. Drain to source resistance reading was infinite.

But when an exhauted 9V battery giving 5.6V was connected from source to gate, the MOSFET had tuned on and Source to Drain resistance was of the order of 0.3 ohms.

Thia condition was preserved even after removing 5.6V to gate. Gate keeps the charge.

Promising. I am curious how will it sound with an output transformer driving the Marzntz Imperial 5-G loudspeaker, MOSFET driven by the SONY D-EJ758CK line out.

 

Update on the Pleiades derivative of simplified no negative feedback Musical Fidelity A1

 At your risk.

Refering to the original Musical Fidelity A1 schematic.

The idea is to try just a BD135 driving a 2N3055 driving an output transformer and no negative feedback.

A BD139 was used instead, a Mitsubishi 2N3055, a bifilar 1:1 output transformer istead of perhaps a more suitable 2:1 output trasformer. Air gap is made by sticking a layer of 3M scotch invisible tpae on the stacked Es.

Vb is 12V.

BD139 is mounted on a small heatsink. 2N3055 is mounted on a larger audio cassette case size heatsink, black aluminium. It run bare touchable hot at 24V.

4R7, 100 ohms, 300ohms resistors are used as on the Musical Fidelity output stage schematic.

Bias is adjusted by a 220Kohm in series with 1Mohm variable resistor from Vb to the base of BD139.

2N3055 Ic was set to about 400mA.

Signal path:

various CDs, Dire Straits, Barbara Streisand, Year of the Cat - Al Stewart - Sony CD Wlkman line out, Pleiades simplified striped down Musical Fidelity A1 - Marantz Imperial 5-G

It worked, it sounded loud, even louder at Vb=24V, Ic=800mA.

Changing 4R7 to 6R8 made for a somewhat more open sound.

Quick changes are posble thanks to using Wago snap connectors.

But there was lack of treble, as if one or two high octaves were missing.

Going back to such a single 2N3055, the sound so softer, less power output but better sound quality, a bit more treble.

Going back to the Pleiades Darlington BD650. It sounded much more open with extended high frequency bandwidth and deep bass too, as if 2 more high octaves were added. Loudness was between the 2 above extremes.

Why does it sound much better? Is it because there are no resistors around the transistors? Should a BD135 driving a 2N3055 be tried in this way with least possible resistors?

The Darlington BD650 at Vb=12V  sounds great at just Ic=100mA, saving charged battery time.

On a small heatsink it run luke warm.

Moving closer to the spekaer at abot 1m from 3 m the sound is even more impressive.

WHat makes this so simple Darlington amplifier stand out is how alive drums sound, hi-hat sounds for example as if there is a hi-hat inside the room, for example of Sultans of Swing - Dire Straits, or On the Border - Al Stewart.