Πως προκύπτουν οι συγχορδίες του Back to Black - Amy Winehouse

Δείτε επισεις το προηγουμενο post στα Αγγλικά.


Το όμορφο τραγουδι, σε σπάνιο ντοκουμέντο ηχογραφισης:
https://m.youtube.com/watch?v=2NVvzRt8fTs#fauxfullscreen


Το μικροφωνο ειναι το ταινιας (ribbon) [αγωγiμη κορδελα (ελεύθερα ηλεκτρόνια) παλλόμενη απο τη φωνη, η  πανλεπτη αλουμινένια κορδελα βριςκεται μεςα σε ιςχυρο μαγνητικό πεδίο)], RCA (Radio Corporation of America) 77DX κατασκευασμένο τουλάχιστον μισό αιώνα πριν. Το σημα η μεταβαλλόμενη μουσικά τάση το περνούμε απο τα άκρα της κορδέλας. Ενισχύεται μετα με μετασχηματιστή και έπειτα με ενισχυτη απο σωληνα ηλεκρονιων η τρανζίστορ.
http://www.coutant.org/rca77dx/


H Amy Winehouse χρηςιμοποιει τον κωδικα Μπαχ οπως δωθηκε στον Μπαχ απο τον μηχανικό Niedt [Bach].


Μπορουμε να πουμε οτι ιςως ο κώδικας Μπαχ προκύπτει απο την αρχή της μικρότερης δυνατής αλλαγής στη μουσική. Αντίθετα ιςως με το τι φαινεται, οι μεγάλες αλλαγές μπορούν να δημιουργήσουν αποτέλεσμα που ακουγεται σαν φθηνό τραγουδι, προνηπιακο. Πχ Ρε Φα Λα και μετα Σολ Σι Ρε.


Ενώ, οπως ο Μπαχ εξηγεί μπορουμε να κρατάμε κάποιες νοτες ίδιες απο την προηγούμενη συγχορδία στην επόμενη.


Συνοπτικά μπορουμε να προετοιμάσουμε τον εγκεφαλο του ακροατή για μια έβδομη η ένατη σε σχεςη με το μπαςο απο την προηγούμενη συγχορδία. Και μόλις το μπαςο αλλάξει ορίζοντας την 7η η 9η να προσθέσουμε και την 3ή νότα σε σχεςη με το μπαςο [Bach]. Ετςι καθε "διαφωνο" διάστημα ακουγεται τοςο ομορφα σαν παράδεισος στην γη.


Παραδείγματα:


Ρε μπαςο με δεξί χέρι Ρε Φα Λα και μετα
Σολ μπαςο με δεξί χέρι Ρε Φα Σιb (ύφεση)


η


Ρε μπαςο με Ρε Φα Λα και μετα
Σιb μπαςο με Ρε Φα Λα


Ειμαςτε τυχεροί που στην χώρα μας εχει ιςως ξεκινήσει πρωτοποριακά να διδάσκεται το Bach Bass Rules σε όλες τις βαθμίδες εκπαίδευσης.


Ας δούμε ομως τον κωδικα μπάσου του Back to Black:


Ρε
Σολ7
Σι7
Λα(3#) σημαίνει η 3ή απο μπαςο δηλαδή Ντο ειναι Ντο διεση


Όλο το μουσικο κοματι προκύπτει απο αυτόν τον κωδικα. Δεν χρειαζεται να θυμομαςτε τίποτα άλλο. Οι αριθμοί σημαίνουν πόσες νοτες ανεβαίνουμε σε σχεςη με το μπαςο. Τα πάντα αναφέρονται στις φυσικές οι λευκών πλήκτρων νοτες. Ντο Ρε Μι Φα Σολ Λα Σι. Αυτες ειναι και όλες οι νοτες. Το αν καποια θα ειναι ύφεση η διεση ορίζεται απο την κλίμακα η σκάλα (διαδοχικές νοτες) στην οποία ειναι γραμμένο το μουσικο κοματι η σύνθεση. Ολα τα διαστήματα αναφέρονται σε σχεςη με το μπαςο, με την απόσταση τους απο αυτο που επιδεικνύεται με τον αριθμό κοντα στο μπαςο.


Ας δούμε λοιπόν πως προκύπτουν όλες αυτες οι εκλεπτιςμενες συγχορδίες η αρμονία...


Το τραγουδι ειναι γραμμένο σε Ρε ελασονα η αλλιώς Ρε μινόρε. Η κλίμακα αυτη εχει καθε Σι, Σι ύφεση. Ειναι η εξης: Ρε Μι Φα Σολ Λα Σιb Ντο Ρε.


Το μονο ιςως που μπορουμε να θυμομαςτε ειναι οτι κανουμε τις λιγότερο δυνατές αλλαγές. Καθε έβδομη λοιπόν για παραδειγμα ειναι προετοιμαςμενη και προσθέτουμε την 3ή. Υπάρχουν και άλλοι τρόποι να προετοιμάζουμε. Πχ μεςω μελωδίας κτλ. Ενα καλο βιβλιο Αρμονίας ειναι του Piston που ήταν και ο καθηγητής του Bernstein στο πανεπιστήμιο Χαρβαρτ.


Ρε σημαίνει Ρε μπαςο και Ρε Φα Λα


Σολ7 σημαίνει Σολ μπαςο και Ρε Φα Σιb


Σι7 σημαίνει Σιb μπαςο και Ρε Φα Λα


Λα(3#) σημαίνει Λα μπαςο και Ντο# Μι Λα


Ας το δούμε και πιο αναλυτικά:


Ρε σημάνει Ρε135 δηλαδή Ρε μπαςο και Ρε Φα Λα


Σολ7 σημαίνει Σολ1357 δηλαδή Σολ μπαςο και Σολ Σιb Ρε Φα


Σι7 σημαίνει Σι1357 δηλαδή Σιb μπαςο και Σιb Ρε Φα Λα


Λα(3#) σημαίνει Λα13#57 δηλαδή Λα μπαςο και Λα Ντο# Μι Σολ


Χρησιμοποιώντας την αρχή της λιγότερο δυνατής αλλαγής στη μουσική έχουμε, (δοκιμάστε πρώτα και μετα δείτε το).


Υπάρχουν πολλοί τρόποι να παιχτεί, διάφορες αναςτροφες κτλ. Ένας απο αυτούς ειναι:


Ρε μπαςο και καπου μετα τη μεςη του πιάνου Φα Λα Ρε
Σολ μπαςο και ... Φα Σιb Ρε
Σι μπαςο και ... Φα Λα Ρε
Λα μπαςο και ... Μι Λα Ντο



Οως προκύπτουν οι νοτες; Ενα καλο σκονάκι να θυμόσαστε ειναι το 1 3 5 7 9 11 13. Πχ Σι Ρε Φα Λα (δεν ειναι απαραίτητο να χρησιμοποιούμε όλες τις νοτες). Ετςι έχουμε πχ Σίb μπαςο και Ρε Φα Λα η Φα Λα Ρε κτλ.


Αυτο ειναι λοιπόν απο την αρχή μεχρι το τέλος σχεδόν. Αν προσέξετε και η χορωδία ιςας τραγουδά αυτα τα μέρη οι νοτες.


Φιλια και απο τον Μπαχ, περιτρυγισμενος απο τοςα παιδιά και γάτες στο σπίτι, ξέροντας ομως τι κανει. Και δίνοντας το απλόχερα σε όλους μας.


Ο Μπαχ μελέτησε πολυ και τους Ιταλούς, Vivaldi, Marcello κτλ οπου εκει φενεται ξεκάθαρα ο κώδικας. Προετοιμάζουμε τον εγκεφαλο του ακροατή με κάποιον τροπο για το διαφωνο διάστημα σε σχεςη με τι μπαςο και προσθέτουμε την 3ή νότα σε σχεςη με το μπαςο.


Αναφορές, πηγες:


Instructions of JS Bach for playing 4 part harmony to his students in music:
(Bach Bass Rules):
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf



Harmony - Piston


Oboe Concerto in D minor, 2nd part - Marcello - transcribed by Bach for keyboard
Bach Keyboard Concertos after Vivaldi, Marcello, Telleman etc - Peters Edition

Music is paradise on earth

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Deriving the harmony of Back to Black

Amy Winehouse as all great composers of the last at least 4 centuries uses the Bach-Niedt code [Bach].


The principle of least change in music is used which may be said to be implemented by the Bach-Niedt composition manual [Bach].


Contrary perhaps to intuition great changes produce results that sound like cheap kindergarten music. For example going from D F A to G B D.


Whereas least change produces beautiful and sofisticated results as notes from previous chords may flow into the next one, preparing the human brain on "disconant" to come intervals and making them sound like heaven on earth. For example (left hand D, right hand D F A) and then (left hand of bass Bb, right hand the same ie D F A).


As an elementary summary we may state that the Bach code is to prepare for example the 7th or 9th interval with respect to bass from the previous chords or by any other way and when bass changes on the next chord adding by another part the 3rd. For example:


Bass           Harmony
D                 D  F  A         (F is being prepared for next chord)
G                 D  F  Bb       (the 3rd from bass is Bb added)


Do not worry about sharps or flats. They are automatically derived from the scale or key used.


All one needs to know is the 7 keyboard white or natural notes CDEFGAB and reference all intervals with respect to bass from them.


So here is as an example how the harmony of Back to Black - Amy Winehouse can be derived:


The numbered bass or bass code [Bach] is:


D
G7
B7
A


And that's it. All this beautiful song is derived from just this 4 line repeating code.


How?


It is very easy.


The scale or key is D minor. This means all B are B flat. The scale is D E F G A Bb C D.


Combining the rules 1 3 5, least change or prepared 7ths etc we have:


Try to figure it out before looking:


Bass Code        Bass          Harmony
D means            D                D F A
G7 means          G                D F Bb
B7 means          Bb               D F A
A(3#)                A                C# E A


So these are the chords or harmony taint repeat from Begining to end.


How do these notes come about? It may heard to think or 1 3 5 7 9 11 13. For example B bass and B D F A (we do not have to use everything). So Bb bass and D F A.


If you listen carefully the backing vocals must be singing these same chords as derived above.


For a perhaps more detailed derivation from bass code to harmony, see next post in Hellenic.






















Reference:


Bach Bass Rules or Instructions of Bach in four part harmony to his Scholars in Music:


https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf

Does increased broadband hiss from DC tape recording bias mean there is more resolution

Nothing is optimized yet. And frequency response should be less than 5KHz, yet it sounds detailed ie not restricted in information conveyed to listener's brain.

Flutter Reberb Echo when using DC bias?

Not investigated yet but while reproducing the 06 track from the original Fame soundtrack some loud singer's sss ie sibilants sound like...


S.s.s.s with decaying reberb. As if reverb has been changed to very quick repeat tape echo which is fading out or decaying.


Strange. Interesting sound.

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Connecting electron tube anode to recording head (part 3)

At your risk. Attention to all safety precautions is important for safety. Also batteries should always be connected in series with a suitable fuse in series to protect from short circuit or fire hazard.


The Pleiades V6 amplifier is used. Cc is 22nF. No input transformer. Head instead of output transformer. Rag is 1.5MΩ.





The sound so far does not rock the earth. But keeps improving. The sense is that it is worth continuing. It is a warm and natural sound.


Today it's first time a Pleiades re-recording is made in stereo by connecting each channel of 1/4 track cassette head to an anode.


Recording signal path:


Is it OK if I call you mine? 06 track from original Fame soundtrack on CD - Sony portable CD player line out - 2x Pleiades V6, EF183, Rag=1.5MΩ - side A, 2 tracks of Tascam Porta 03 head - TDK SAX type II cassette


Playback signal path:


TDK SAX cassette - Sony TC-D5 Pro II - Sennheiser HD580


The head is connected between Vb battery (+) and anode ie instead of an output transformer or impedance coupling inductor.


The following tests:


1. Feeding heads with 3.6V, ie Vb=3.6V.


Interesting first time stereo sound with this setup. Somewhat lower output. Somewhat more treble. Somewhat more distortion. Nice sound. Hiss sounds thick like playing a vinyl record. Head is under biased at around 250μA. When music stops, the thick hiss can be heard with some HF components.


2. Just one EF183 electron tube feeding both head coils for 1/2 track mono. This experiment is a preliminary to using all 4 tracks simultaneously for close to 2'track stereo on cassette. Vb=7.2V.


Better sound? Maybe. Less distortion? Yes. Bias for each coil should be 500μA. More treble than expected as the 2 head inductors are in parallel making a half inductance total, see RL filters or Pleiades filters. Treble Less or not as nice as test 1. More tape modulation, approx +3VU.


3. Back to stereo with 2 electron tubes and Vb=5.5V. At this stage 7.2 volt can't be used as with 1.5MΩ from anode to grid anode current is 1000μA. On previous test each coil shared 500μA. 1000μA completely saturates tape.


Nice big and thick sound. Still lacking treble but not in an objectionable way. Some harmonic distortion. Playback VU meters hit at times +3VU and more. Thick hiss noise heard only when song had been paused while recording. Why? Does brain ignores thick hiss while the song is being played? Or does bias noise decrease as the music signal rides above and below it?


Funnily enough this hiss cannot be heard while music is playing.


This may be good news.


But the song does not sound bright yet as there is no gap loss recording amplifier treble boost for compensation.


When cathode heaters are disconnected while recording treble increases. This must be because of 2 reasons. DC bias decreases. Anode internal resistance increases so the head is fed more correctly with constant current with respect to frequency.


It is funny hiss when recording had been paused sounds like lifting the tone arm while music is playing on record.


How to move forward?


Sticking with around 250μA-400μA tape bias ie plate (anode) current but increasing plate supply voltage. Therefore the pull up bias resistor has to be increased for given supply voltage until anode current reduces to 400μA. Would this create constant current conditions up to a higher frequency? Ie increasing of available recording voltage for high frequencies.


It is interesting recording with just one electron tube per channel on magnetic tape.


How would it sound at 7.5ios on cassette or 7.5ios or high on reel to reel 1/4in?

How does DC bias hiss sound like?

This is on sending about 500μA to a cassette head, tape running at normal speed.


When the recorded song (Is it OK if I Call You Mine, track 06 from the original soundtrack of Fame CD) is played back, the noise sounds somewhere deep below the music.


If the source CD player is paussd while recording, what is heart from the playback cassette is a deep thick hiss noise. It reminds a lot the noise heard when the stylus of an MM cartridge lands on groove before the song begins.


Not perhaps as beautiful noise, as it is missing the static noise from the vinyl.


It gives a sense of bigness to the sound perhaps like on vinyl. Of course what we hear is the filtering integration of the playback circuits.


So far playback (without boosting gap loss etc treble while recording) sounds a bit distorted with a nice distortion, warm and big.


All done in order to record is connecting the head to the anodes of 2 Pleiades V6 electron tube amplifiers (1 electron tube per channel) while battery powering the heads with a 5.4V potential. (All safety precautions should be followed when experimenting with power, ie voltage or current).


In fact the hiss as expected sounds much better is stereo even if the recoding is mono.


See also next post.

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Leaving grid at space potential and connecting anode to tape recording head

Would Vb=18V be enough and the control grid floating? (Attention to any voltage for safety) (a suitable fuse must always be used for current safety too). And then perhaps if everything sounds fine increasing cassette magnetic tape speed to 7.5ips. Or a nice portable reel to reel tape recorder running at 7.5ips or more.


According to some previous tests on Pleiades V6 used as a mic booster. Using the EF183 grid at space potential and anode supply of 9V gives an anode current of 25μA. Doubling Vb increases anode current many times as there is the penetration of the anode field to grid [Deketh]. See previous posts.


If for example a current of 400μA is desired but is not achieved by Vb=18V then either the anode supply must be increased or a suitable megohms value of anode to grid resistor chosen.


Or using other electron tubes. The 1H4 seems to have a large anode field penetration affecting grid space potential.


See also:


https://euroelectron.blogspot.com/2018/10/connecting-directly-tape-recording-head.html


Fundamentals of radio valve technique - Deketh - Philips
Technical Library

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Automatic recording bias according to signal strength

It is amazing how low noise noise a virgin demagnetised tape is.


AC bias produces noise.


DC bias even more and it is somehow mid bass pitched. So far tried on cassette at the normal low speed. See previous posts.


The sound quality looks very promising (DC bias).


When the signal is large noise is masked anyway by the signal itself.


What if:


A side chain DC signal is created according to signal strength by the usual methods of rectification, RC filtering of the signal itself like used in compressors.


And applied as DC bias to the recording head.


In such a way that when there is no signal input, bias is zero. And the tape has max quietness.


Then as signal is increasing bias is increasing too bringing the BH operating point to the middle of the positive quadrant transfer curve.


This sounds like an expander or gate but how would it sound like?


Using DC bias it seems much easier applying this idea.


An electron tube directly connected to recording head (with all safety precautions) may cooperate with the recording head and electron tube bias will translate to head bias. See previous post.



A way to reverse DC bias direction can be to first saturate the tape by a permanent field erasing head and then applying a DC recording bias shifting the operating point down.


These are possibly bad engineering ideas...


Anyway AC bias can be used too in perhaps a similar line of thought.

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Connecting directly a tape recording head to a battery powered electron tube part 2

Attention. Any voltage can be dangerous. At your risk. Take all safety precautions. Also a suitable fuse should be used with any battery for fire hazard protection.


It is beginning to get more interesting.


Today it is the first time on Pleiades experiments that a magnetic tape recording head is connected directly to anode or plate. In place of an output transformer.


So there is treble rise due to the high output Z of electron tube (as is done with all analog tape recorders since the head (inductor) is driven at constant current). And there is DC at least bias of the magnetic tape as the anode is direct coupled to recording head in an attempt to operate it at its linear BH characteristic. And attempting to use the minimum possible number of components.


Summary: At 250μA to 500μA anode or recording head (quiescent or DC current) it worked. It was possible to record a cassette at least up to +3VU. There was more treble compared to connecting the 2N3053 transistor as recoding amp due to the higher impedance of the electron tube. But the Pleiades 2N3053 has been tried only operating from 1.3V whereas the EF183 electron tube was tried today at a range of plate potentials from 3.6V to 12V.


The Pleiades V6 schematic was used without input transformer and with the recording head of a Tascam Porta 03 transport instated of the output transformer. Pleiades bias or further pull up bias from anode to grid was used to shift away the electron tube from cutoff and make it operate the usual way with just few volts at the plate.


A range of anode currents i.e tape DC bias currents from 2.5mA to 200μA were tried. They were produced by only changing the Vb or plate (anode) supply of the Pleiades V6. And also by under heating the cathode by disconnecting the heater supply observing sound quality change as the cathode temperature decreased.


A time lag exists for listening tests as the cassette has to be removed and played to a Sony TC-D5 Pro II each time a change to recording conditions is made.


Referring to the Pleiades V6 schematic:





If no Rag resistor is used (no Pleiades or further pull up bias) the grid is negative to cutoff since the cathode thermally emitting its electrons becomes positive. The electron tube is sleeping.

Both electron tube and magnetic tape are at cutoff. As soon as the electron tube negative bias is decreased by Rag both electron tube and tape wake up as the tape is no longer at its low part of positive quadrant cutoff. By biasing the electron tube, the tape can be biased too at its center point of the straight part of the positive quadrant BH curve.


It sounds the electrons are waking up.


In fact electrons are always at thermal motion or noise agitation waked up by the sun. The electrons in the cloud around cathode are at greater thermal motion by the nearer cathode at high temperature. What do electrons, spinning or orbiting ones? do inside the tape magnetic domains? Who knows?


2 channels of Pleiades V6 amplifiers had already been sort of prototyped from previous experiments directly driving the Sennheiser HD580 300Ω per channel headphones. At the moment one channel was only connected to recording head, L channel part of side A.


Referring to Pleiades V6 scheMagic, instead of an input transformer there is a potentiometer. A CD player line out is feeding it.


Signal path on recording:


Is it OK? 06 track of Fame soundtrack on CD - Sony portable CD player line out - Pleiades V6 with Cc=22nF, Rag=1.5MΩ - recording head of Tascam Porta 03 instead of output transformer - TDX SAX 60 type II cassette running at normal speed


Signal path on playback:


TDK SAX cassette - Sony TC-D5 Pro II - Sennheiser HD580


These Pleiades V6 amps used were kind of optimized for direct driving the HD-580 headphones, see Pleiades Electra 3.


This was done by reducing the EF183 internal plate resistance by increasing as much anode current at low plate voltage. This was done by a relatively low ie 1.5MΩ pull up bias resistor from plate to grid. Circuit fed by 12V. The output impedance should be around 5 KΩ which may be too low for driving a tape recording head. So such heavy pull up bias may be a disadvantage.


So here is how the first Pleiades recodings with anode direct to tape were done. All batteries must be used in series with a fuse for safety including fire hazard. Various Vb, anode supply voltages needed were created by various series combinations of AA rechargeable batteries.


A 12 V battery is powering 2 EF183 electron tubes (for each channel) heaters in series. So there is no deliberate imderheating. This too proved to be possibly a disadvantage.


But let's see how the head was driven by various plate supply potentials.


Initially HD580 headphones were connected at anodes to check everything sounds ok. The sound was amazing. With fantastic treble for a CD reproduction.


Then the head was connected. Surprise. At reproduction there was no sound. Only some deep heavy hiss. It was apparent that the tape was saturated by anode current. Ia was measured 2.7mA so tape bias was 2.7mA DC.


Then plate supply or Vb was changed to 3.6V. Unfortunately the potentiometer was by mistake reduced to a lower signal input to the EF183. It worked. There was sound. Modulation was a few dB below 0VU. Ia was 250μA.


Then Vb was changed to 7.2V and another recording proceeded. Ia=1mA. Almost no sound. There was sound only when disconnecting the heaters while cathode temperature was being reduced.


But then accidentally while reconnecting the HD580 to check something and after increasing signsl input to EF183, they were left connected by mistake. The recoded sound was great. Tape modulation as seen on playback was +3VU, there was no distortion. Treble of course was lacking as the output impedance was lowered by the headphones. It seems the headphones shared the current and indeed the DC bias was 600μA. So this may be a value to aim for.


Then headphones disconnected and Vb=6.5V was used giving a DC bias of 700μA. At last it started working. There was treble loss. And modulation increased for same conditions when disconnecting heaters. It seems 700μA is too much.


Then Vb=5.5V was used. Anode current or DC tape bias was now 500μA. Great. Modulation increased. It worked. There was treble loss. Hiss was kind of thick midband. Barely head when music was playing.


Then Vb=3.6V was used again but this time driving the EF183 more at the input. It worked. There was more treble. More distortion. But a nice sound. Hiss seemed to be less. Disconnecting heaters with no music playing gives a chance to hear how bias noise reduces to the so low value of the virgin tape as cathode reduces emmision of electrons.


Conclusion:


Bias values from perhaps 200μA or less to 500μA might be aimed for.


For increasing treble, the impedance of the amp has to be increased. Ie increasing output voltage but reducing output current and certainly the quiescent anode current. What is needed is an increase in power by increasing supply voltage but without increasing the anode current. The recording head is an inductor and can be driven at constant current with respect to frequency ie rising voltage with rising frequency. This is done by driving the head with a high output impedance.


So for example Vb=12V can be tried but with much less pull up bias. For example arranging Rag so that Ia is 400μΑ.


Or even Vb=18V with no pull up bias?


How would the circuit sound by leaving the grid at space potential and supplying anodes by 18V?


See also part 3:

https://euroelectron.blogspot.com/2018/10/connecting-electron-tube-anode-to.html

Why do we have increase in treble when an inductor is connected in aparallel?

It is an R L circuit or filter. It is driven by an output resistance R.


Every source of voltage, AC or DC has a non 0Ω output impedance. Effectively Rout is a series resistance. According to Ohm's law when we draw current the voltage drops at this resistance. A potential devider.


Connecting an L in parallel is the opposite of connecting a capacitor C in parallel which reduces the high frequency content.


The impedance of C decreases as frequency rises. So it becomes increasingly towards being a short circuit. So the output voltage of the source is forced to drop.


The opposite with an L. As frequency increases its impedance increases. So the source is less and less loaded and there is treble increase.


See also L Pleiades microphone filters and gentler slope (R,L) Pleiades filters connected in parallel with mic output.


Other example is driving a magnetic tape recording head. It is an inductor. So if it is driven by a high output impedance which is the case, the voltage across it increases as frequency rises.


Other example is an output transformer if it has a low inductance compared to the output impedance of what drives it.

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Wolfgang Amadeus Mozart

https://m.youtube.com/watch?v=kdBypYaEexQ#fauxfullscreen


From the film Amadeous.

Confutatis - Mozart

https://m.youtube.com/watch?v=fjtwyZAhCcs#fauxfullscreen


It might seems completely incomprehensible how this great harmony comes about.


But if you study a score including the bass (which is missing above) you may realize that:


A great key to understand is that the 7ths with respect to bass are prepared from the previous chord and then the 3rd with respect to bass added [Bach, Niedt].


For example:


At 1:12 bass becomes E.


The altos with be ne di ctis prepare the 7th note which is D. (E to D is an interval of 7 notes). Immediately as bass becomes E the sopranos add the 3rd wrt bass which is G.


A harmonic chain [Piston], caries on where each woman voice group in turn prepares the 7th and the other ground adds the 3rd. Everything with respect to bass. So all those fabulous major seventh chords are prepared for the listener's brain [Bach].


https://m.youtube.com/watch?v=zEOybKIrxSk#fauxfullscreen


The same played in a less midi way:
https://m.youtube.com/watch?v=74_rHWFz-AI#fauxfullscreen


References:


Bach Bass Rules:


https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf


Harmony - Piston


Comfutatis - Motzart, from film Amadeous
https://m.youtube.com/watch?v=kdBypYaEexQ#fauxfullscreen

Canelina the cat, her 2 new fairytales

2 new fairytales in Hellenic on the next 2 posts.


One on the song This Girl's in Love with You - Burt Bacharach, Hal David, singer Dionna Warwick, producer Phil Ramone and how the Bach code is applied from the beginning. By preparing the sevenths with respect to bass and then adding the third wrt bass [Bach, Niedt].


The other fairy tale is on Velvetine, the German cat and how she tries to eat the best food avoiding white flour, sugar, trans fat which is refered to as vegetable oil etc so that she enhances her health, cleverness and beauty.


Reference:


Bach Bass Rules:


https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf

Η Κανελινα και η γάτα Βελουδίνα τιγρακι

Προσοχή. Το παραμυθι αυτο δεν αποτελεί ιατρική συμβουλή. Με δικη σας ευθύνη.


Ήρθε το φθινόπωρο. Η Βελούδινα με τους γονεις της εχει επισκεφτεί την Ελλαδα. Κατι ξέρουν.


Η ομορφη αυτη γατούλα φίλη της Κανελινας και της υπομονετικής χελώνας δεν ειναι σαν τις άλλες γάτες.


Κατ' αρχήν ζουν οι παππούδες και γιαγιάδες της χωρις να έχουν πάθει έμφραγμα. Η προ γιαγιά της δεν εχει σακχαρώδη διαβήτη...


Το τρίχωμα της βελούδινας ειναι σαν το ποιο μαλακό, απιστευτο βελούδο. Ειναι πολυ εξυπνη και φιλική και και με τους ανθρωπους. Κανει απιστευτο τραγουδιστικο και χορευτικό σόου οταν βλεπειε νέους ανθρωπους καθε ηλικίας. Αν στέκεται κανεις ακίνητος, μπορει να τρίβεται ευρώ απο τις γαμπες σου κάνοντας ατέλειωτους γύρους η τροχιές σε σχήμα οκτώ περνώντας ανάμεσα απο τα ποδια σου.


Και φυσικά γνωρίζει τον κώδικα Μπαχ [Bach-Niedt] ,στον όποιον ειχαν πιθανοτατα προςβαςη τοσοι μεγάλοι μουσικοί συνθέτες, απέξω και ανακατωτά. Μπορει ακομα και να γράψει μουσική χωρις να το πολυσκεφτεί. Η εξυπνη Αγγλίδα γάτα Λούσι μπροστά της δεν τολμά να κανει φιγούρα για συγχορδίες.


Οι γονεις της ειναι υγιείς και γλυτωνουν όλοι πολλα χρήματα για ιατρική περίθαλψη. Σε παλιότερες διακοπές αγόρασαν το βιβλιο προληπτικής ιατρικής [Καραβης]. Ετςι έρχονται καθε χρόνο στην Ελλαδα για διακοπές.


Η Κανελινα δεν έχανε στιγμή να την παρατηρεί. Ειδε οτι αντίθετα με τις άλλες γάτες τρώει ωμους αναλατους ξηρούς καρπούς. Πχ αποςτευτα καρυδια και φυςτικια Αιγηνης. Και οταν μπορουςε Τα κόβει οταν μπορει και κατευθείαν απο το δεντρο. Της αρέσει ο Κρητικος ντάκος (100% κριθάρι), μαύρες σταφίδες, το σουςαμι ολικής, το ταχίνι ολικής κτλ. Το ολόφρεσκο ψάρι κτλ. Εννοείται ομως οτι τρώει και αλλα λαχταριστά οπως τυρόπιτα και κρουασάν. Οταν ομως ειναι σπιτικά φτιαγμένα με αλεύρι Ζέας, παρθένο ελαιόλαδο η φρέσκο βούτυρο και οχι μαργαρίνη η φυτικά trans λιπαρά που έχουν τη φήμη να φράζουν τις αρτηριες αίματος.


Αυτο ομως που εκανε εντύπωση στην Κανελινα ειναι οτι η Βελούδινα ενώ όλοι της έριχναν λευκό ψωμι, τυρόπιτα, κρουασάν και οτι άλλο ήταν φτιαγμένο με λευκό αλεύρι, ούτε που το κοιτούσε.


Μια μέρα λοιπόν ενώ εκαναν βόλτα η Κανελινα πήγε να πάρει κουλουράκι. Εκει η Βελούδινα που είχε καταλάβει οτι την παρατηρούσαν τόσες μέρες της την είπε για να την ταρακουνήσει.

Αν ήξερες πόση εξυπνάδα κρύβεις μεςα σου δεν θα το έκανες αυτο. Ιςως γι'αυτο ποτε δεν καταλαβαίνεις τίποτα οταν μιλάει η Λουσι για συγχορδίες και το Bach Bass Rules που σχεδόν ολα τα ομορφα τραγούδια και συνθέσεις το χρησιμοποιούν.


Η Κανελινα δεν άντεξε και έβαλε τα κλαματα. Έτρεξε στην παραλια στους σοφούς γλάρους να τις εξηγήσουν.


Οι σοφοί γλάροι πανω στον βράχο τους που προεξέχει λιγο απο την θαλαςςα, σκέφτηκαν λιγο και της ειπαν.


Η Βελούδινα ιςως εννοεί την αλευροκολλα.


Η Κανελινα συνεχιςε να κλαιει, δεν καταλάβαινε τίποτα.


Ιςως εννοεί συνέχισαν οι γλάροι οτι το άσπρο αλεύρι με τόση γλουτένη, και λίγη ζάχαρη στη ζύμη, το φοινικόλιπος που ειναι σαν κερι, ολα αυτα μπορει να φράζουν μεςα σου και να μην λειτουργει όσο σωστά μπορει οι εγκεφαλος σου. Να κολλάει λιγο. Να ρεταρει. Πως το λένε...Πως το καρο βαλτώνει στην λάσπη...


Πλάκα εχετε είπε η Κανελινα που αρχισε να σκουπίζει τα δάκρυα της. Τι ειναι γλουτένη;


Αν την απομονώσεις μοιάζει με αυτήν την ντομάτα παιχνίδι που την πετάμε στο πεζοδρόμιο και κολλάει σαν...


Σαν χλαπατσα πρόσθεσε η Κανελινα. Και θυμήθηκε πως μοιαζει το αθώο κουλουράκι, φθηνό κρουασάν, φθηνό ψωμι του τοστ και φρυγανιά με φυτικά trans λιπαρά οταν πέσουν στο νερό. Σαν νιανια. Ετςι γίνεται και μεςα στο σώμα μου;


Μπράβο ειπαν οι σοφοί γλάροι. Ξέρεις... για λόγους που δεν γνωρίζουμε την εποχή που μάλλον απαγορευτικε η καλλιέργεια του δίκοκου σιταριού στην Ελλάδα και αρχισε να χρηςημοποιηται το κολωδες λευκό αλεύρι, στην Γερμανία έγινε μάλλον το αντίθετο. Καλλιεργούσαν το σπελτ που ειναι παραλλαγή του δίκοκου. Και ετςι οι Γερμανίδες γάτες τρώνε ολικής ντινκελ ψωμι κτλ.

Η Κανελινα πετάχτηκε απο την χαρά της. Εντάξει κατάλαβα είπε. Τους φώναξε ολους και μαζι χόρεψαν και τραγουδιςαν κατω απο τις ακτίνες του πρωινού Ηλιου που δεν αφηνει καμια σκια στην αλήθεια.


Πηγες:


Πως κατάντησε το Ψωμι - Μπαζαιος


https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf


Προληπτική Ιατρικη - Γιαγκος Καραβης - Πύρινος Κοσμος

Η Κανελινα και το This Girl's in Love with You - Burt Bacharach

Η Κανελινα και η υπομονετική χελώνα μαζι με την γάτα Λουσι ακούνε ραδιόφωνο και ξαφνικα ξεκινάει το This Girl's in Love with You - Burt Bacharach, Hal David, φωνη Dionna Warwick, μοθςικος παραγωγος (μουσικός σκηνοθέτης) Phil Ramone.


Αμέσως πετάγεται η Λουσι με σκοπό να αρχίσει φιγούρα και αρμονική ανάλυση....


Τις κλείνουν το στόμα η Κανελινα και η υπομονετική χελώνα. Της λένε... άστο μεγάλη, κάηκες...


Και σαν αστραπή προσθέτουν...


Εκει που ξεκινάει να τραγουδάει η Dionne... This Girl '(s in) love, Ντο# Ντο# Ντο# Ντο# ειναι προετοιμαςμενη μεγάλη έβδομη αφου το μπαςο απο Λα γινεται Ρε. Και το πιάνο πρόσθετει την 3η σε σχεςη με το μπαςο [Bach]  δηλαδει Φα# η Φα διεση.


Μετα το μπαςο θα ξανα ανεβεί μια 4η θα γίνει δηλαδή Σολ. Ετςι το επαναλαμβανόμενο Φα# στο πιάνο  με τις σειρα του θα γίνει προετοιμαςμενη μεγάλη έβδομη. Αφου μεταξύ Σολ και Φα η απόσταση ειναι 7 νοτες.


Και τώρα η Dionna θα προσθέσει την 3ή που ειναι Σι για να ακουστεί η μεγάλη έβδομη πανέμορφα στον εγκεφαλο του ακροατή [Bach]. This Girl's in love with you. Ντο# Φα# Ντο# Λα Σι Σι...


Η Λουσι έμεινε άφωνη...


Και οι τρεις τους ταυτοχρονα πρόσθεσαν...


Οπως στο Comfutatis του Mozart στο δεύτερο πέρασμα της γυναικείας χορωδίας. Ποτε οι άλτο προετοιμάζουν καθε έβδομη κανονική η μεγάλη και ποτε οι αλτο προσθέτουν την τριτη νότα απο το μπαςο. Και μετα εναλαξ. Αρμονική αλυσίδα, harmonic chain [Piston] οπως στο Corcetro για τσέλο σε Ντο ελαςονα του Antonio Vivaldi.


Οι τρεις φιλενάδες γέλασαν.


Η Κανελινα πετάχτηκε απο την χαρά της.


Και όλες μαζι φώναξαν και τους άλλους με επίτιμη προσκεκλημένη την γάτα Βελούδινα τιγράκι και κατέβηκαν στην παραλια.


Και χόρεψαν και εκαναν μπάνιο με τους σοφούς γλάρους και τα μπλατσουριστικα σπουργίτια This Girl's in Love with You. Κατω απο τις πρώτες ακτίνες του Ηλιου που δεν αφηνει καμια σκια στην αλήθεια.


Πηγες:


Bach Bass Rules - Bach, Niedt


https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf


Harmony - Piston


Confutatis - Mozart (only choir score shown, no bass)
https://m.youtube.com/watch?v=fjtwyZAhCcs#fauxfullscreen


Confutatis - Mozart - full score


Comfutatis - Mozart - from the movie Amadeous
https://m.youtube.com/watch?v=kdBypYaEexQ#fauxfullscreen


Confutatis - Mozart - piano arrangement
https://m.youtube.com/watch?v=74_rHWFz-AI#

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Welcome to Belarus

Hello to Portugal

Hello to Ukraine, Unknown Region and France

Τα μυστικά του ήχου του Χόλυγουντ, Hollywood

Τίποτα δεν ειναι μυστικό.


Τα παντα υπάρχουν γυρω μας αρκεί να γνωρίζουμε τι θελουμε και τι ψάχνουμε.


Τότε οι καλύτεροι του Χόλυγουντ μηχανικοι απο τα καλυτερα στουντιο συγκέντρωσαν οτι σημαντικο και γράφτηκε το βιβλιο Motion Picture Sound Engineering. Οπως και το Elements of Sound Recording - Frayne, Wolfe


Εκει εξηγείται σε ανώτερο επίπεδο οτι τις περισσότερες φορες πρεπει να το κανεις "λάθος" για να ακουστεί σωστά.


Ένας ηλεκτρονικός μηχανικος, ο Μικες Ψαλίδας ύστερα απο παράκληση του Φίνου να βρει γιατι οι ελληνικές ταινίες δεν ακούγονται σωστά μελέτησε και αυτα τα 2 βιβλία και κατασκεύασε παθητικά εκουαλαισερ με πηνια με την βοήθεια του φίλου του Τάσου Φουσέκη. Επισεις ζήτησε στον Φινο να γίνει συνδρομητής του Journal Of Society of Motion Picture Engineers, πράγμα που άμεσα έγινε. Θα παθητικά πηνια βοήθησαν στην γραμικη απόκριση συχνότητας οχι απο μικροφωνο σε ηχείο αλλα απο τις φωνητικές χορδές του ηθοποιού η τραγουδιστή στον εγκεφαλο,του ακροατή [Lowe, Morgan].


Ετςι τότε με σωστή ηχογραφιςη του Παιδια του Πειραιά - Χατζιδακις, Ζορμπας - Θεοδωράκης πήραμε Όσκαρ.


Και με το Δρόμοι της Φωτιάς - Παπαθανασιου. Και εκει πρεπει να έπαιξε ρόλο. Ο Μικες Ψαλίδας είχε κατασκευάσει 2 κονσόλες ήχου με σωλήνες ηλεκτρονίων και παθητικά EQ. Μια για την Φίνος Φιλμς και μια για τον Βαγγέλη Παπαθανασιου.


Τα πηνια τυλίχτηκαν σε υπόγειο αεροπορικής εταιρίας στην πλατεία Συντάγματος απο τον Τασο Φουσέκη [Φουσεκης].



Αναφορές:


Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - Journal of the Society of Motion Picture Engineers


Οι οχτώ κύκλοι - Τάσος Φουσέκης (ιςως δεν εχει εκδοθεί ακομη)

Summary of electric sound recording and reproduction

It is converting (with a microphone) air molecule vibration (music) to corresponding electron vibration.


Then converting electron vibration back to air molecule vibration (with a loudspeaker).


The air molecule vibrations do not have to be the same at the output compared to the input. They might have to be only when reproduced acoustic sound pressure level or intensity is the same as acoustic intensity when recording.


If intensities are different which is usually the case (in any popular music production) the impression to the listener's brain will be very far wrong. The frequency response of the human ear, brain depends on acoustic intensity [Lowe, Morgan]. Also the bandwidth of human singing or speaking voice depends on effort or acoustic intensity output. Soft singing produces a much greater bandwidth [Lowe, Morgan].


Therefore suitable EQing by the best possible equipment is needed so that flat frequency response from the brain of the producer to the brain of the listener is achieved [Lowe, Morgan].


Reference:


Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - Journal of the
Society of Motion Picture Engineers


Further reading:


Motion Picture Sound Engineering


Elements of Sound Recording - Frayne, Wolfe

Hello to Netherlands, Germany and to Ελλας

Pleiades V6 driving headphones

A Pleiades V6 without an input transformer and instead of output transformer the voice coils of Sennheiser HD580. See also Pleiades Electra 3 or EF183 power amplifier.


Signal path:


Fame soundtrack CD - Portable Sony CD player line out - 2x Pleiades V6 with EF183, 12V - Sennheiser HD580


Power supply is 12V. One EF183 electron tube per channel. Possibly no cathode underheating. Anode supply 12V. Fuse in series with battery for safety. Same battery powering both heaters in series and anodes through headphone voice coils. So ground of headphones is connected to + battery. Battery in series with suitable fuse.


Pull up bias is by a 1.6MΩ resistor from anode to grid.


Amazing sound. Possibly the best treble that can be heard out of a CD. The headphones seem to be constant current driven as the output impedance of the amp should be around 5KΩ.


How would this amplifier sound directly connected to recording head coils of a reel to reel recorder or a cassette recorder running at 7.5ips? Perhaps decreasing bias so that less current is flowing through the head so that the tape is biased at near mid point of straight part of BH curve. It should be tricky. Both electron tube and recording head should be simultaneously biased at the correct point. Bias of the electron tube will affect both electron tube and tape. This is DC bias for the recording head or tape which should be more noisy. If DC bias proves too noisy or not giving desired max output level from tape then AC can be used. See nearby posts. In the meantime it so much simpler to experiment with DC bias, no components should be needed, just DC coupling of a high output impedance driving the magnetic tape recording heads.

Analog Hackers

It should be fun to hack a portable cassette recorder to run at 7.5ips, 2 track stereo.


According to the tiny air gap of cassete recorder heads could it be equivalent to 15ips reel to reel?


Is it worthwhile? Increasing motor voltage (attention to warm up or fire hazard safety). Changing to simpler class A (electrons flowing all the time) electronic amplifier stages with simpler wave filters or EQs as in top quality reel to reel tape analog recorders.


Reel to reel 7.5ips or higher sounds so nice anyway.

Hello to Germany

Hello to Germany, Finland, Ελλας and to United Kingdom

Driving a magnetic head directly from a single ended battery amplifier, the Pleiades 2N3053

The Tascam Porta 03 was used as transport with direct connection to its head.


Signal path:


On recording:
the song Is it OK if I Call you mine? from Fame soundtrack CD - Sony Portable CD Player line out - Pleiades 2N3053 one transistor amplifier - magnetic head side A, L channel, biased at 1mA DC - TDK SAX 60 new cassette


On reproduction:
Is it OK if I call you mine? TDK SAX - Sony TC-D5 Pro II - Sennheiser HD580


Before connecting the head to Pleiades 2N3053 output, the Sennheiser HD580 headphones were connected to check sound quality. It was very good but the amplifier was slightly overdriven by line out. It operated at just 1.3V. (Always use a fuse in series with a battery for safety).


Then the headphones unplugged, the head was connected and play was pressed to move the tape.


DC bias current is 1mA.


Then the cassette was taken to Sony TC-D5 Pro II for reproduction.


It worked. Sound came just from the left headphone. It did not sound like chewing sand. This is because there was DC bias from the 2N3053 collector. Ie direct coupling to collector and battery, the head inbetween the two (with fuse for safety).


The sound was not good.


It was like a bass midrange telephone.


The vocal reminded of someone singing to a mic without an R,L Pleiades filter in parallel with the mic.


There was lack of high pass filtering.


The Sony TC-D5 VU meter showed up to -5dB.


There was some bass hiss noise. Mostly apparent when the song was paused while recoding. As it seems noise comes from the DC bias.


After this single take, another one was recorded but this time on top of it was recorded again the same song. It worked, both sounds could be heard together but distortion was much worse. And it sounded as if the bias was much less. The output was much less than when the head records at one pass.


A possible cause for the bad sound is that the output impedance of the 2N3053 transistor is about 300Ω or less. So there is impedance match with the head. And the head is driven at constant voltage with respect to frequency rather than constant current wrt frequency.


The much higher output impedance of an electron tube amplifier, eg Pleiades V6, should be tried or a series resistor at the output of transistor etc. All precautions for voltages of any magnitude and safety should be strictly followed. Even if it a battery powered amplifier such a the Pleiades V6. And a series fuse with any battery must be used for current warming up safety or fire hazard in case of a short circuit.


Looking through at a JVC cassette recorder and the Uher 4200 portable reel to reel schematics a 22K or 10K resitor respectively can be seen in series feeding the recording head. The resitor has a few nanofarads (nF) shunt capacitance possibly making an additional high turn over gentle slope high pass, RL Pleiades filter. The resistor in itself with the shunt inducstnce of the head form a 6dB per octave high pass filter, a 6dB per octave Pleiades L filter. This slope is then reversed in a playback amplifier until a some turnover frequency, defined by the μS time constant. For example 70μs for IEC 7.5ips. (μ ie micro comes from the Hellenic word μικρο pronounced mecro with short e sound meaning little or tiny). So after some frequency we stop reducing the treble at playback to compensate for head gap compared to recorded wavelength losses etc.


It is not known yet what is the optimum DC bias current.


If memory is correct sound on sound on reel to reel recorders with erase head disabled sounds a lot better, at 7.5ips.



For better news on quality of sound see part 2:
https://euroelectron.blogspot.com/2018/10/connecting-directly-tape-recording-head.html

Connecting a cassette recorder playback head directly to mic in

A Tascam Porta 03 was used just for transport and its head.


Signal path:


Denon DX90 cassete, recorded in the 90's - Tascam Porta head, L track side A - SONY TC-D5 Pro - Sennheiser HD580


The impedance of the head is 250Ω so very similar to a moving coil mic. The multi pin connector was carefully removed from the Tascam board and a nice balanced connection was made with small aligator cable clips to XLR in.


It worked and when the Sony rec level was at max the VU meters went up to 0VU.


So in terms of signal strength it is similar to a 200Ω mic when one sings softly.


To repeat, this is a playback head directly connected to mic in of a system of flat electrical frequency response.


The sound was appalling.


It sounded like an almost bad quality telephone, carbon stuff and worse.


Bass and treble was missing and mid was like barking. Like coming from a bad gramophone horn.


It is amazing what playback equalization does to cassette tape. It seems to do not only integration ie low cut or high pass but treble boost too.


Of course things would be much better if the cassette tape was running at 7.5ips.


To compare, connecting an MM vinyl record phono cartridge to high Z mic in, electron tube grid for example, gives as sound of full treble, like bats or birds singing but it is an interesting and nice sound.


See next post on how driving the head directly form an amplifier with DC sounds like.

Hello to Finland and United Kingdom

Hello to Germany and France

Flat frequency response from producer's brain to listener's brain with a specific recording characteristic

What if...


One drives a recording head with such a high impedance source (plus AC or DC bias) that constant recording current is achieved up to a very high frequency. Or anyway doing anything needed until a flat mic becomes close to sounding corect from singer's vocal chords to listener's brain...


Ie removing all the bass heaviness that results from all causes discussed in previous posts [Lowe. Morgan].


And keeping the playback integration (high cut) characteristic at given tape speed which is standard anyway.

How would a carbon mic sound connected to a tape recording head?

Recording without an active device.


With its nice DC, biasing the tape.


Just a battery in series between the two and a fuse for safety. The fuse better be thinner than the recording head wire.


It may not work nicely. The driving impedance must be large to create constant recording current wrt frequency. But who knows?


Some of these questions may happen because of Panos discussing years ago about connecting a music signal to a head without even constant current premphasis and listen to what will happen.

Hello to Germany and to the Netherlands

Hello to Ukraine

Is one transistor or electron tube from line out to recording head possible?

For example initially connecting a CD source line out to a Pleiades V6 or Pleiades 2N3053.


Then using the recording head as output transformer and the passing DC becoming magnetic DC bias to bring the tape to its linear operating center or slightly of center operating point.


Technically it is not a one transistor recording as there are thousands of transistors inside a CD player.


If it works with good quality it may show that a 2 to 3 transistor minimal signal path recorder is possible from mic to tape.


Would it produce a nice sound on sound too by re recording many times the tape without using an erase head current?

Comparing tape noise from AC or DC bias in practice

A normal (type I) Fuji DR60 cassette was used.


A portion of Side A had been passed from the permanent magnet erase head of Sanyo TRC-2500 portable cassette recorder with the recording AC head bias either not operating or at a very low level due to malfunction.


Another portion of Side B had passed through the Sony TC-D5 Pro II with REC levels at 0 and pad at -20dB, so in practice there is no recorded sound.


The increase of noise of Side A, Side B was compared with adjacent virgin parts of side A or Side B as vergin tape being degaussed? from the factory.


Playback of both sides were compared on the Sony TC-D5 Pro II with Sennheiser HD580 headphones.


The subjective noise impression was as follows.


The virgin tape of course is the most quiet. How different are side A or side B to this reference?


In fact this was not the reference. The reference set was the amplifier noise when the Sony was in pause mode.


By comparison to pause mode noise:


Vigin tape sounded 4 times louder.


AC bias noise impressed to tape from Sony TC-D5 sounded 8 times louder.


DC bias noise to tape from Sanyo permanent magnet DC erase head sounded 16 times louder. The main difference was that the noise was not only HF hiss but it was a broadband noise containing bass components too.


DC noise was large but perhaps not as much as expected. This type of DC bias can be equivalent to 8mA passing from an erase head. See yesterday's post on JVC erasing DC current as shown in the service manual.


Would a recording bias of a few hundred microamperes or less be adequate for nice recording including sound on sound and of a much lower noise?

Good morning to Germany and to Ukraine

Recording random canons or random music

Can ambient music be created by re recording many types the same tape by re passing it through the recording head but with the erase head disabled?


Monitoring is not impossible but it may be difficult.


So why not exploit this difficulty by not monitoring at all.


For example recording the same melody many times. Each take may be completely different in time length, when it begins or ends etc, phrasing etc.


Recording loops of different time lengths Brian Eno style.


Creating random music...


Much like over painting on the same canvas but not looking what is already there.


Of course some rules must exist. For example using the same scale ie the same notes, using a step bass etc, some repeating patterns etc.


Would it be fun?

Overdubbing by magnetically printing (recording) many times the same tape

This involves disabling the erasing head and see what happens when recording the same tape many times.


Which method is better for this in terms of least affecting what has already been recorded. AC or DC bias?

How would push pull DC bias sound like on each half track of a magnetic tape?

Would it be more quiet?


For example recording the same audio signal on each track but with reversed DC polarity. Then summing the 2 signals. Would some bias induced tape noise be statistically canceled?


Would this technique help sound on sound? Ie recording many signals on each pass of a tape by disabling the eraser head?


Would reversing the polarity of DC for each overdub even on a single track tape produce batter noise results? Or a larger reversed DC bias as tape is nonlinear.

How did HF AC bias came about for magnetic tape recording anyway?

If memory is correct...


First it might had been DC bias.


Then one day the inventors noticed a particularly good sounding prototype.


It was investigated and it was found that the recording amplifier accidentally oscillated.


The old saying.


If you want to build an amplifier, build an oscillator.


And if you want to build an oscillator, build a amplifier.

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How would a push oull class C amplifier sound AC biased at a high frequency?

This is possibly a silly question just out of curiosity.


Bias on magnetic tape recording seems to operate this way as a magnetic material eg demagnetized, demagnetized head laminations, tape is self biased to cutoff [Hellyer].


Yet magnetic tape recording sounds so nice. AC bias effectively shift the operating point to the centre of the H-B characteristic on both positive karts of the X,Y axis and the negative quadrant.


Perhaps a bit like making 2 push pull electron tubes operate in class A (electrons flowing all the time).


Class A operation creates least distortion for small signals and saturation if the larger peaks.


But perhaps the title is a very silly question. We can just bias 2 or even a single ended electron tube or transistor with DC. DC looked as a step function has indinite bandwidth (see Fourier transforms).


Why is AC high frequency bias used on magnetic tape? This is possibly for noise considerations. The noise of a demagnetized tape increase when passed through AC bias. But it should increase even more when passing through DC bias [Hellyer]. Also both quadrants of the H-B magnetization curve are used. Like using a push pull amplifier instead of a single ended one. So maximum output level should be more.


Perhaps DC bias for example by using the head as an output transformer in transistor or electron tube circuits may be investigated in Pleiades experiments. (Attention to any voltage, all safety precision must be strictly followed).


How do signal transformer get away with it? If we look at the magnetising current when a sine wave voltage is applied it looks seriously distorted with crossover distortion. But possibly because exactly the same core carries the magnetic flux to link the secondary there is an exact cancellation and the secondary reproduces in realtime almost at the speed of light a sinewave too.


Do transformers with a bit of DC bias sound better or lower noise?


Reference:


Tape Recorders - Hellyer

How would a magnetic tape recording head sound like used as an output transformer?

Attemtion. Any voltage can be dangerous. All safety precautions should be strictly followed.


This is on DC bias of magnetic tape. Possibly all books say AC bias is better. A very nice book explains both DC and AC bias is [Hellyer].


How would a recording sound like with the recording head being the output transformer itself?


For example on Pleiades Electra 1.2 or 3.


On Pleiadss 2N3053.


On Pleiades V6.


Just sending a music signal to a recording head does not recorded almost anything. The demagnetised tape is by nature magneticaly biased to cutoff. So only the peaks are recorded which is exactly the opposite of what is wanted.


A magnetic head looks almost exactly like an output transformer for a single ended amplifier. The magnetic laminations. The winding or windings. 2 in fact air gaps. Hmmm...


A DC current flowing through the recording head can bring the magnetic operating point of tape near the mid point of the straight part of the BH curve characteristic. For example on the positive X,Y quadrant.


How would it sound like? At high tape speed too?


How would then superimposing another recording sound like?


Would the head polarity have better be reversed for the next overdub?


Anyway. There seems to be a great analogy. We change, ie pull up the bias of an electron tube so that it can operate at say 6V plate voltage without cutoff (pull up or Pleiadss bias) and this same bias procedure pulls up the magnetic operating point or bias of the recording tape.


Sounds nice. Mabe it is a very silly idea.





Reference:


Tape Recorders - Hellyer

Pull up bias of magnetic recording head

Inductance and impedance of various magnetic heads

There must be a previous post. This one may concentrate in measuring the inductance at both 1.28KHz and 96Hz. Measurments by Escort ELC - 120 LCR digital meter.


Philips cassete recorder head, blue type New Old Stock
120mH at 1.28KHz
170mH at 96Hz
250Ω at 1.28KHz
(Looks like a microphone voice coil?, stepping up by a microphone transformer?)


Photovox? new old stock head for FBT PA echo
950mH at HF
1.11H at LF
1.22KΩ


SONY head in car cassete adaptor CPA-11
53mH
650mH at LF
2.6KΩ


Heads of 4 track Tascam Porta 03 cassete recorder
133mH at HF
190mH at LF
250Ω AC impedance

Singing in practice to a backing track with MD211 N

It was decided to sing this time while music is being heard in the background coming from a speaker in an adjacent room.


The Is it Ok if I Call You Mine? was used from the original 80's Fame soundtrack.


Surprise.  Although the Wetesrn Electric transformer was used which reduces a bit bass heaviness by its 1H primary inductance and projects voice ...


The sound was more bass heavy than expected. It seems there is an additional effect of masking of high frequencies by the backing track. A deep low slope high pass filter made the singing voice register similar to the original backing track song.


In fact since the song playing on the CD was the original with the singer, it was really singing along with him and a very direct comparison could be made between registers in real time.


Setup, signal path:


Portable Sony CD player - Pleiades 2N3053 power amp - Philips AD5046N 800Ω speaker


male singing voice - (Pleiades 130Ω,40mH) filter - Western Electric 1:2 step up transfomer - Sony TC-D5 Pro - Sennheiser HD580


Without an R,L filter the voice sound was somewhat bass and mid heavy with none of the sparkle of the original vocal.


With the 130Ω,40mH Pleiades filter the vocal became bright and sparkling. Perhaps even more than needed. Annoying chestiness was gone. So it sounded quite similar to the original vocal. R,L values can be fine tuned.


The particular RL filter used may or may had not been too much. But it sounds that an RL Pleiades filter should definetly be needed.


The quality of treble on voice was excellent from such a wonderful world class microphone. Noise was minimal. The Western Electric transformer (1H:4H) did I an excellent job of further reducing any plosive, pops etc by its Lenz's law damping action or its sub bass reduction.

Hello to Germany and to the Netherlands

Would DC bias allow more effective sound on sound recording?

This is on recording sound on sound by disabling the erase head. (See previous today's posts).


Would DC bias be more effective in affecting what has already been recorded less?


To give some perhaps relevant figures...


Refering to a typical 70's JVC cassette recorder's service manual. JVC NIVICO 9425LS.


Erase DC current is 7mA!


Record head AC bias current is 900μA.


Recording current at 1KHz is 60μA.


Would a DC bias current of the order of 60μA do the trick?


How would a Pleiades V6 battery powered electron tube amplifier operating in this or larger current area sound like with the low voltage anode connected directly to the head on a reel to reel tape transport? Ie connecting the recording head instead of the output transformer? Of course more than one amplifying stage should be needed from mic level to magnetic tape.

Playing with electrons part 2

See for example next posts.

Bulk Tape Erasers

This has not been tried.


According to the book [Hellyer] a well erased tape may be even more quiet than when new.


Reference:


Tape Recorders - Hellyer

Connecting the recording head directly to anode, drain, collector Ie DC bias

At your risk All safety precautions should be exercised.


Biasing for a magnetic material is very similar to biasing a transistor or electron tube for example.


We need to shift the operating point to the linear portion of the transfer characteristic.


DC bias can be employed on tape recording [Heelyer]. But it uses only the positive part of the magnetization curve. And it will also produce increased noise [Hellyer].


Nevertheless a DC signal has an infinite bandwidth. See Fourier transforms.


And it should be simple to try.


How would a recording sound like for example on a cassete running at FF speed? Minimum EQ if any should be used on playback. Just a full low pass filter at 6dB per octave on reproduction? The high driving impedance of active devices would produce constant current drive wrt frequency of the recording head which is what is normally used on tape recording.


Reference:


Tape Recorders - Hellyer