Wednesday, May 30, 2018
Tuesday, May 29, 2018
Technology moving so fast that important findings are left behind
For example it has been well known for decades than ear brain octaves are very different from engineering octaves (x2 frequency). [Gauffin, Sundberg]. In general the human brain wants many more Hz so that the octave sounds correct. And it depends on how high the notes are. Pitch itself also depends on acoustic intensity. [Stevens]
Yet so many modern electronic tuners, midi setups, synthesizers are made ignoring this important knowledge and sounding like cheaper than cheap toys. [euroelectron]
Would a great editor of the excellent Wikipedia edit the article on Octave? [wikipedia]
Frequency and pitch are 2 different notions. Frequency is number of cycles per second measured in Hz, 1Hz is by definition 1 cycle per second. Pitch is the sensation of height of tone measured in Mels. [Stevens]. The word Mel comes from melody. There is not such thing as pitch in Hertz.
Of course great music is great music and great producers intonate by ear brain so that the music sounds correct to millions of listener's brains. For example the very high notes of the song I've had the Time of my Life from the Dirty Dancing soundtrack.
Another example of important knowledge that may be left behind perhaps undiscovered is the fact that electron tubes can brilliantly amplify with just a few volts anode voltage supply instead of hundreds of volts. This is possible if internal electron cloud negative bias is neutralized by an external positive voltage source. See for example the Pleiades V6 microphone head amplifier.
References:
Octaves and Pitch - Gauffin, Sundberg
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.431.8104&rep=rep1&type=pdf
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html
Ear brain octave vs engineering octave - euroelectron
The Pleiades tuning - euroelectron
http://euroelectron.blogspot.com/2018/05/the-great-sounding-octaves-of-casio-mt.html
https://en.m.wikipedia.org/wiki/Octave
Sound and Hearing - S. S. Stevens, Warshofsky - Chapter 4: The Mind's Influence - Life science series
Pleiades V6 schematic - euroelectron
Another interesting article on ear brain octaves with many references
Octaves and pitch - Gauffin, Sundberg
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.431.8104&rep=rep1&type=pdf
The great sounding octaves of Casio MA-100
Octaves sound very nice to human ear brain on the cheap overlooked Casio MA-100.
By monitoring frequency using a vintage cathode ray tube Hohner tuner indeed the high notes are higher than "equal" temperament. Bravo to Casio.
It sends to the cleaners instruments with many more zeros on the price tag.
See also the next euroelectron post on how each note sounds great too.
Compared to the nice MT-65, MT-100 the higher notes are even higher. And each overtone must be too as each note sounds very natural, easy and pleasing.
The Pleiades tuning (open source) is an attempt to make great sounding synthesizers such as the DX7ii and Korg Triton have great sounding octaves to listener's brain.
References:
Ear brain octave vs Engineering octave - euroelectron
Octave Stretch - Terhardt
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html
The Pleiades tuning for Yamaha DX7 ii, Korg Triton - euroelectron
Just one musical note can sound magnificent
There may be many reason why a note can sound so good.
An important one is the overtones of a particular note of fundamental frequency f to be slightly more than x2 f, x3 f, x4 f .., etc so that it sound correct and pleasing to ear brain.
Great pianos, orchestras (each individual instrument), pipe organs do this.
But sometimes very few specimens of very cheap electronic instruments can do this. One example is the Casio MA-100. Not only does each note sound nice, (for example the voice Street Organ) but but each note is tuned so that high octaves sound correct to ear brain by having the right amount increase of frequency from "equal" temperament.
In summary the wrong amount of inhamonicity (lower or higher frequencies than needed by the human ear brain) sounds bad. What is wishfully called harmonicity (exact x2, x3, x4, x5 frequency,...) sounds appalling. The right amount of inharmonicity sounds perfect. For example the great large Steiway grand pianos. Other example is the very high instrument notes of the song I've had the time of my life from the Dirty Dancing soundtrack.
References:
Ear brain octave vs engineering octave - euroelectron
Octaves and pitch - Lindqvist-Gauffin, Sundberg
Octave Stretch - Terhardt
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html
http://historicaltuning.com/StretchingOctaves.html
Bibliography:
Musical Acoustics - Donald Hall
Monday, May 28, 2018
History of the Academy of St. Martin in the Fields
Narrated by Sir Neville Marriner on this informative interview:
Adventures in Music featuring Sir Neville Marriner
https://m.youtube.com/watch?v=v38SGEcclkU#fauxfullscreen
Oxalic acid and calcium
At your own risk. This is not a medical advice.
These are just some articles found to be interesting. Somehow the impression is that problems begin when there is protein from animals and junk food in the diet. Do your own search.
http://www.realfoodforlife.com/oxalic-acid-controversy/
https://www.cretalive.gr/health/petres-stoys-nefroys-diatrofh-aytes-oi-trofes-sas-prostateyoyn-ti-na-prosechete-omos
https://www.nutritherapy.gr/index.php/el/blog/item/33-ουρικό-οξύ-το-πολύπλοκο
Sunday, May 27, 2018
Measuring high note intonation of great musicians
Does a paper exist on this subject.
Engineering octave (2xfrequancy) and ear brain octave are not the same thing. Our brain needs more than x2f, x4f, x8f otherwise it sounds cheap and small, flat.
This is an excellent publication on the subject. Octave equivalence - Terhardt:
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octequiv.html
At very high notes the difference what our brain wants and what simple intenger multiplication of frequency gives is magnified.
So, how far up is Dave Gilmour's intonation on the highest note of Comfortably Numb - Pink Floyd on the electric guitar solo towards the end of the song from "equal" temperament calculations?
Is it close to half semitone up (from "equal" temperament calculatiins) so that it sounds perfect and breathtaking to those millions of satisfied Pink Floyd listeners.
How about the high note intonation of the great St Martin in the Fields Orchestra conducted by Sir Neville Marriner. For example on Corcierto d' Aranjuez part 2.
How about the very high notes from the electronic Solina String Ensemble organ on those brilliant French band Air songs possibly inspired by the high note night forest sounds of Versailles? Is the recording studio near the forest? How much was the master tuning control of the Solina increased so that those very high electronic string notes reminds us that we are humans?
Other fabulous sounding high notes that would be of interest to be measured are on the song I've Had the Time of my Life from the movie Dirty Dancing.
See also the Pleiades tuning.
Is inputing numbers on an online tone generator while the music is being played at very low acoustic volume a way to do these comparisons? Low volume is needed, as pitch depends on acoustic intensity, so that meaningful comparisons can be made. Here is a brilliant online sinewave generator
http://onlinetonegenerator.com
Reference:
Engineering vs ear brain octave - euroelectron
Bibliography:
Sound and Hearing - S. S. Stevens, Warshofsky - Life science series - from page 77, The Mind's Influence
(Engineering) Octave Strech - Terhardt
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html
Octave Equivalence - Terhardt
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octequiv.html
Saturday, May 26, 2018
The importance of tuned snare to the song key
Lefteris mentioned this many years ago.
Alexandra too.
(There is a mistake on this post. The example song Be my Baby - Spector is in E major and not in F major. The snare sounds close to E).
An example:
Be my baby - Spector, in F major
The snare drum although a percussion instument is strongly giving the impression of the note F. It is a constant note or pedal note as after the drum is in tune with the song key it stays there.
Being in tune with the song sounds great and creates all those interesting intervals with (from) bass. For example when the bass is C the interval is a 4th reminding of the beautiful 4,5 to 3,5 chord used so much by Antonio Vivaldi. On Vivaldi music one can encounter for example bass F going to C going to F. Chord notes A,C,F going to (G,C,F and quickly to G,C,E while bass is still C) to A,C,F.
Bibliography:
Bach bass rules:
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf
Harmony - Piston
Pleiades high, low pass microphone filter schematic
_________________________________________________
| |
( _|_
) L ___ C
( |
mic in | | mic out
< <
> R1 > R2
< <
________________|____________________|____________
Pleiades high, low pass wave filter schematic
R1, R2 can be variable for variable steepness slopes.
For a 200Ω mic a typical potentiometer value of R1 may be 300Ω.
R2 should normally be higher.
L together with the mic impedance defines high pass turnover point.
C together with mic impedance defines low pass turnover point.
The wave filter should sound great are it is a minimum component signal path, with no active devices with feedback such as op amps etc.
The inductor is preferably wound on a ring tape wound magnetic core to avoid alternating magnetic field noise pickup. A ring shape creates a very efficient closed magnetic circuit where minimum magnetic flux leaks out and minimum magnetic flux leaks in.
See also improved Pleiades filters.
The objective of the use of the Pleiades wave filter is flat frequency response from producer's brain to listener's brain. [Lowe, Morgan].
The wavefilter can be connected to a microphone input transformer.
A low noise head amp may follow such as Pleiades V6. It consists of input transformer, EF183 electron tube, output transformer, 4V battery for both heaters and anode.
Pleiades concepts and schematics are open source.
References:
Improved Pleiades Filters - euroelectron
Pleiades V6 schematic - euroelectron
Flat frequency response from brain to brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.E.
Bibliography:
Motion Picture Engineering
Elements of Sound Recording - Frayne, Wolfe
Feynman Lectures in Physics
Conceptual Physics - Hewiit
Electromagnetism - Grant, Phillips
Simple Psychoacoustic Experiments
These are simple and very meaningful experiments. Simple yet powerful.
One can find out how the human brain perceives height of tone. Frequency is the objective engineering or physics stimulus, pitch is what we feel, what our brain perceives as height of a note. Frequency is measured in Hz. Pitch is measured in Mels from the word melody.
Acoustic volume should be turned down low to avoid damage of your ears or your speakers.
All that is needed is an online sinewave generator:
http://onlinetonegenerator.com
You may see how pitch perception changes as acoustic intensity increases. By keeping frequency constant to 440Hz for example. You will notice that even slight increase in volume will lower pitch (perception).
You may also listen to how 1600Hz sounds a very bad or flat double octave of for example 400Hz. Our brain wants more than 4x400Hz or 1600Hz. How much more you need and how much more your friends need you may discover yourself.
Keep volume down.
Our speakers ooops our ears are precious.
Bibliography:
Sound and Hearing - S. S. Stevens, Fred Warshofsky - Life Science Series
A slightly lower than x2 in frequency octave may sound horrible where as a slightly greater than x2 may sound brilliant
This psychoacoustic effect is even more prominent at double, triple octaves etc.
For example choosing a A3 note to be 220Hz, A5 at 880Hz will sound flat or a sick or an uninteresting multiple octave. A5 890Hz will be much better. It may depend on who is listening. It may even depend on which ear.
Experiments can be done with an online sinewave signal generator.
Acoustic intensity should be kept low as pitch depends on acoustic intensity too.
References:
Online tone generator
http://onlinetonegenerator.com
Engineering octave vs ear brain octave - euroelectron
Sound and Hearing - S. S. Stevens, Fred Warshofsky - Life Science Series
http://www.mmk.ei.tum.de/fileadmin/w00bqn/www/Personen/Terhardt/ter/top/octstretch.html
Variable slope high pass, low pass filter with 4 components, the Pleiades passive filter
This is how it is made:
One inductor L connected in series with a variable resistor R1.
One capacitor C connected in series with a variable resistor R2.
The 2 networks are connected in parallel.
The mic 2.3 terminals are connected in parallel too. (Attention to condenser mics, this filter is connected to the output of a mic. If a ribbon or moving coil mic or bass guitar pickup coil is used they would not mind, other active devices may do mind at some setting). Just an inductor has already been used on previous Pleiades experiments with classic electron tube condenser mics with no problem. Your own risk.
Pleiades Filter schematic
_________________________________
|
(
) L
(
in | out
<
> R
<
__________________|_________________
Pleiades filter schematic
A similar filter can be used after this with a capacitor in series with a resistor for high cut or low pass.
So many curves of any slope can be made on either side of the spectrum.
If variable or many L or C are used it will be a parametric EQ.
By adding a variable resistor in series with the source of signal a parametric filter may be possible by using just one inductor.
The improved Pleiades filters for electric bass
The new version of Pleiades filter is an inductor in series with a resistor. So it is a more general case. When R=0Ω ie no resistor we have just an inductor.
The passive filter is connected to the output of a bass instrument. L together with the output impedance of the instrument dictate the high pass or low cut frequency, R adjusts the slope. It can be a variable resistor. No makeup gain is needed. The wave filter removes what is not wanted.
For example if a bass guitar or an electronic bass synth etc sounds dull, with no treble detail, muddy, undefined to listener's brain, by removing the unwanted bass heaviness the overall sound may become a clear and deep bass with mid and treble detail.
Inductors can be easily wound on toroidal tape wound cores which suffer no magnetic pickup noise as the magnetic field is contained inside the ring.
Mu metal, nanoperm (nanocrystaline), moly permalloy, supermalloy etc tape wound cores can be used.
Pleiades filters can be also used directly connected to a microphone output. Be careful,in case some active microphones may not accept the load. They operate greatly directly connected to moving coil or ribbon microphones.
The schematic of the Pleiades filter is in the next euroecrron post:
http://euroelectron.blogspot.gr/2018/05/improved-pleiades-filter-schematic.html
The objective is helping in creating the right sound with minimal signal path. Flat frequency response from producer's brain to listener's brain.
A similar fikter may be used for high cut. It may consist of a capacitor in series with a variable resistor and the total in shunt or parallel with the signal source output.
Reference:
Flat frequency response from brain to brain, Sound Picture Recording and Reproducing Characteristics - Lowe and Morgan - J.S.M.P.E.
Friday, May 25, 2018
Simplifying Pleiades Filters?
This may not be simpler but it is just another way inspired by looking at the Electro -Voice academy award winning 642 microphone internal 2 position filter.
The filter is connected to the 50Ω output tap of the mic.
So why not when winding one's own ring core input transformer not include a very few turn (low impedance) winding tap to the primary or secondary. Or even a few turns of a third winding.
So say a 10Ω local output impedance is created.
Then making an inductor cutoff filter would be very easy. A very small inductance is needed for given cutoff. Only s few turns. This filter will be connected in parallel or shunt to the low impedance winding.
And a resistance can be added in series to this external coil for a variable low cut or high pass slope. See improved Pleiades filters.
References:
Electro-Voice 642 engineering data from the Coutant site.
http://www.coutant.org/data/642.pdf
Improved Pleiades filters - euroelectron
Pizza
The video how to make perfect pizza - Gennaro Gontaldo
https://m.youtube.com/watch?v=1-SJGQ2HLp8
The story of Concierto de Aranjuez - Rodrigo
It begins at 21:30 of Joaquin Rodrigo 90 years documentary
https://m.youtube.com/watch?v=huhKfYUbkyA#fauxfullscreen
The BBC report on Beyer M160 microphone
BBC research department report L-061, 1965/32:
http://downloads.bbc.co.uk/rd/pubs/reports/1965-32.pdf
There is no correct frequency for E5?
This applies for any note. For example C6, D7, A2.
The right frequency for example for E6 will depend on the key the music is written. It may be different if the bass is C helping create a C major chord. It may be different if the key is C sharp minor (Moonlight sonata played with an orchestra for example) and the bass is C sharp helping create a C# major chord. It will be different if the key is F major and the bass is F helping to create a F major 7th chord, when the bass is A helping create an A minor chord.
Why is this so?
Because a particular bass note from a particular bass instrument, for example the string of a double bass etc will create certain overtones (modes of vibration from a certain string). A good orchestra might match the particular overtones of a bass instrument to what a high flute is paying at that particular moment. Perhaps the best musicians and conductors find the best compromise in real time as music unfolds from all instruments in real time.
There are other reasons, for example the intensity of a particular note. Pitch does not only depend on frequency but on intensity too.
It seems a complicated subject but in reality all that is needed is the musicians making sure that it sounds pleasing and correct to the listener's brain. Good musicians are listeners of themselves and the room when they play.
What do electronic tuners have to do with all this.
Nothing. They are very good at measuring engineering octaves that have almost nothing to do with human brain octave or other pitch perception.
See also nearby euroelectron posts:
Reference:
Ear brain octave vs engineering octave - euroelectron
Bibliography:
Musical Acoustics - Donald Hall - Wadsworth
How would the high electric guitar notes of world class guitarists measure with an electronic tuner?
For example the high notes from the great solo of Comfortably Numb - Pink Floyd.
Or high notes from Still Got the Blues - Gary Moore or Carlos Santana etc.
An online sine wave generator can be also used for measuring frequency by comparison.
Acoustic levels must be low as pitch (perception of height of a frequency) depends also on intensity.
If the notes of Dave Guilmor are measured to be high, be careful not to quickly judge Dave or the electronic tuner.
Dave as all great musicians when playing is intonating according to what a human being's brain wants to hear (ear brain octaves etc).
And the electronic tuner?
The electronic tuner is based on engineering octaves (integer multipleas of a given frequency).
Ear brain octaves and engineering octaves are not the same thing. Why should they be?
See also nearby euroelectron posts.
Reference:
Ear brain octaves vs engineering octaves - euroelectron
The Philips AD5046N with 9710AM is meant to produce correct frequency response off axis
Just one PHIlIPS AD5046N with the 9710AM sounds brilliant anywhere in a house. See for example the posts on AD5046N driven by Pleiades 2N3053 single transistor power amplifier.
Another reason may be because it is more bright if one is in front of it so that it sounds balanced off axis when one moves around while listening to music which is usually a case.
Reference:
Audio Amplifier Systems - M. D. Hull - PHILIPS application book 1970 - data on 9710AM
Measuring high note intonation of great orchestras
The experiment is simple.
Music containing high notes from a great orchestra are played in the room at low volume (pitch perception depends on intensity).
A steady high note for example is matched to an online tone generator by inputing numbers until it sounds right to human brain perception.
Then the value in Hertz is compared to ordinary frequency, note tables. Or the note from the online generator is measured by an electron tuner. Or an electronic tuner directly listens to a steady high note from a great orchestra.
One is for a great surprise.
The electronic tuner will show all high notes to be substantially sharp.
There is nothing wrong with great orchestras nor with electronic tuners.
The difference is that great orchestras play for humans using human brain perception octaves whereas the electronic tuner measures engineering octaves which are exact integer multiples of a lower frequency.
This experiment can be repeated for various great electric guitar players bending by ear brain the high notes. For example Comfortably Numb - Pink Floyd electric guitar solo at the end.
See also nearby euroelectron posts:
A simple experiment to demonstrate human brain perception music octaves
Using 2 tunable electronic organs. For example Casio MT-100.
The violin sound is used in both with no vibrato.
One instument is tuned higher (using the master tuning knob at the back of the instrument) so that its high D sounds a satisfactory multiple octave to the other instrument's lower D.
Then a simple melody is played using the same notes on both instruments but using the lowers notes from the first instrument together with the higher notes from the other instrument.
The experiment is then swaping instruments to see which combination is best sounding. Ie which instrument is to prefered for the low notes and which for the highs.
It sounds horrible if the high notes are played by the lower tuned instrument.
It sounds brilliant if the Hugh notes are played by the higher than 440Hz tuned instrument.
Brilliant here means in the league, of Mile Oldfield, Vangelis, Pink Floyd Dave Guilmour high bent notes tuned by ear brain, Academy of St. Martin in the Fields high notes etc.
See also the next euroelectron post for more examples.
Electronic tuners wrong?
Why should they be right?
They are based on engineering x2f octaves, not ear brain perception octaves.
An example:
At 7:16 of the following 90 years Rodrigo music video documentary:
https://m.youtube.com/watch?v=huhKfYUbkyA#fauxfullscreen
one can listen the instruments of one of the best orchestras on the planet playing the melody D, E, F, E, D, G...
It sounds brilliant, the notes at high resisters sound brilliant, in tune, greatly intonated.
If one tunes for example an electronic instrument to this sound so that it's high notes sound correct to the high notes of this music extract from this video then this electronic instrument will be found to be tuned many cents above another electronic instrument which was tuned with an electronic tuner. For this experiment a Casio MT-100 was used which has external tuning capability. Compared to another normally tuned Casio, when both organs play the same high notes the beat is very fast, perhaps more than 10Hz, more than 10 beats per second, suggesting 10Hz higher for the instrument tuned to the high note of the orchestra. For this experiment the violin sound was used with no vibrato.
Assuming the conductor did not ask musicians to tune above 440Hz for A4 it is clear that the human brain wants those highs to be higher in frequency than the engineering relation of x2 in frequency asks.
A better experiment would be to sample (or use granulab, a granular synthesis software) such a high note from a brilliant orchestra or other brilliant orchestras then play the sample at long duration and let the electronic tuner show that the note is much higher that it wants to hear.
This is because human brains want it to be higher.
Another nice experiment could be using an online sound generator trying to match the high notes of a brilliant orchestra, then reading the value in Hz and then comparing to what is expected from engineering x2 in frequency octaves. Acoustic intensity levels should be low as human brain pitch perception depends also on acoustic intensity.[Stevens]. Are you in for surprises?
Bibliography:
Human brain vs engineering octaves - euroelectron
The Pleiadss tuning
Sound and Hearing - S. S. Stevens, F. Worshofsky - Life Science Series
Thursday, May 24, 2018
Fletcher Munson Curves, equal loudness curves, ισοφωνικες καμπύλες
They are so important that they may be considered the bread and butter of sound engineering.
For example mixing at too low monitoring acoustic intensity may create a bass heavy mix. Mixing at too loud monitoring acoustic intensity may create a bass light mix.
It is great that newer engineers are more and more aware of their importance.
It is also very important to keep our ears to safe expose levels.
Stelios Giannakopoulos, one of the main recording engineers at EMI Columbia Athens was constantly aware of their importance, not only practicing the art, but reading and consulting the acoustician George Papanikolaou.
An example recording by Stelios Gannakopoulos:
Πρωτη Φορά - Πλέσσας, Παπαδόπουλος, Κουμιωτη
https://m.youtube.com/watch?v=k7ZciKttjww
Οι ισοφωνικες καμπύλες αν και εμφανίζονται στην αρχή βιβλίων περνούν κάπως απαρατήρητες. Ειναι ομως ιςως οτι πιο σημαντικο μπορεί να κατανοήσει ένας, μουσικός, μηχανικος ήχου, παραγωγος, ακροατής.
Επισεις ειναι σημαντικο να προστατεύουμε το πολύτιμο δώρο της ακοής φροντίζοντας να ειμαστε σε ασφαλή έκθεση ήχου.
Ένας απο τους κυρίους μηχανικους ήχου στο στουντιο της Κολουμπια, ο Στελιος Γιαννακοπουλος που μεταξύ άλλων ηχογραφισε τους περισσότερους δίσκους του Μανου Χατζιδακι είχε συνεχεια αυτη την αναφορά στο μυαλό και το ηχοληπτικο του έργο. Σημασία εχει να ακουστεί οτι εχει στο μυαλό του ο συνθέτης σωστά στο μυαλό του ακροατή.
It can't be overemphasized how important it is that what the composer or producer has in mind is correctly heard at the mind of the listener.
Some musical examples:
This girl's in love - Warwick
https://m.youtube.com/watch?v=Gd2Q8VCk9co&list=RDGd2Q8VCk9co&start_radio=1#fauxfullscreen
When I fall in love - Nat King Cole
Bibliography:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.S.E
An elementary description of Fletcher Munson or equal loudness curves
For example an instrument or orchestra is playing in the desert. (Disregarding the fact that air absorbers high frequencies).
When one is so far from the music source that the acoustic intensity is very low only the mid frequencies can be heard.
As one comes closer the perceived bandwidth increases.
The closer one comes the more bass and treble perception is increased.
It follows that if one mixes at a too low acoustic volume the result will be bass heavy at higher volume.
If one mixes at very high monitoring acoustic intensity the result will be bass thin at lower volume.
How would 3 part bouzouki harmony sound like?
How would it sound like writing for 3 part (3 voice) bouzouki?
Perhaps leaving space between notes. For example 3 bouzoukis each playing one note but not for example C E G, but C G Eoct etc.
Wednesday, May 23, 2018
If you don't have anything to hide you are free
Bibliography:
Epictetous - Enchiridion
https://www.stmarys-ca.edu/sites/default/files/attachments/files/Enchiridion.pdf
Public browsing history
If one wants, it might not be such a bad idea. Everything then is under the light of sun.
For example someone at a personal blog may let others know what interesting websites or videos were discovered.
For example a nice video is this:
Jamie Oliver cooking wood fired pizza
https://m.youtube.com/watch?v=9SzxPAkd5UM
Making Great Pizza
Here are 2 nice mouth watering links:
Jamie Oliver cooking wood fired pizza
https://m.youtube.com/watch?v=9SzxPAkd5UM
How to make pizza dough at home - The New York Times
https://m.youtube.com/watch?v=k7ZciKttjww
Ενα ωραιο κόλπο ενορχήστρωσης του Μιμη Πλεσσα
Να ειναι πρωτη, δεύτερη φωνη 6ες, (αναστροφή τρίτης) αντί 3ες.
Για παραδειγμα στα μπουζούκια του Πρωτη Φορά:
https://m.youtube.com/watch?v=k7ZciKttjww
Απο σχόλιο του μηχανικού ήχου της Κολουμπια, Στέλιου Γιαννακόπουλου. Στα διπλανά euroelectron posts.
Στέλιος Γιαννακοπουλος για τον Μιμη Πλεσσα
Στο διπλανό euroelectron post.
http://euroelectron.blogspot.gr/2018/05/some-comments-of-columbia-studios.html
Αναφέρεται το έξυπνο κόλπο του Μιμη Πλεσσα να εχει πρωτη και δεύτερη φωνη στο μπουζούκι 6ες και οχι 3ες. Για παραδειγμα Σολ, Μι οκτάβα αντί Μι Σολ. Δηλαδή η δεύτερη φωνη να ειναι πιο ψηλά απο την πρωτη.
Some comments of Columbia studios engineer Stelios Giannakopoulos for composer Mimos Plessas
Stelios Giannakopoulos one of the main engineers of EMI Columbia Athens studios after 1962 says about composers songwriter Mimis Plessas that he was:
A master of orchestration, very skilled in the art of leaving frequency spectrum space so that the vocal can be perceived by its pristine glory.
Plessas would also write double parts for example for bouzouki not in the ordinary way of 3rds but also inverted 3rds or 6ths. For example instead of E,G he would write G,Eoct.
An example recording at Columbia studios is the following clearly depicting the importance of leaving space for the voice as well as the 6ths trick.
The song is recorded by Stelios Giannakopoulos in one of the newer Columbia studios, either studio 1 or 2 which started operation after 1964.
The song is written in B minor. The rhythm is 9/8. (Notice how each bar cycle completes after every 9 beats, close to heart beats).
The recording is direct to stereo analog tape with usually a Neumann U47 for each instrument. Everything, possibly the vocal too is being played live and mixed live to stereo on 2 track magnetic tape).
The echo room (reverberation or echo chamber) in the basement can be clearly heard. The power amplifier driving the speaker was a Leak electron tube according the decision with Columbia studios technician Giannis Dimitriou. The speaker possibly a Goodmans full range. And the microphone picking up the reverberation in the echo room possibly a Neumann U47.
Πρωτη Φορά - Plessas, Papadopoulos, Koumioti
https://m.youtube.com/watch?v=k7ZciKttjww
Tuesday, May 22, 2018
The sound of Bouzouki at EMI Columbia Athens, Ο ήχος του μπουζουκιού στην Κολουμπια, Ριζούπολη
Πως φτιάχνονταν ο ήχος του μπουζουκιού στο στουντιο ηχογραφησης της Κολουμπια στον Περισσό Ριζουπολη. Αντιχηση προσθέτονταν στέλνοντας τον ήχο στα echo rooms στο υπόγειο των στουντιο 1 και 2. O απευθείας ήχος του οργάνου χωρις κοντινές ανακλασεις με χιλιάδες καθυστερημένες ανακλασεις. Περισσότερα στοιχεια παρακατω.
Recording as few early sound reflections taking place near the instrument, adding to the dry signal thousands latter (delayed in time) reflections from the echo room (echo, reverberation chamber). Περισσότερα στοιχεια παρακατω:
A microphone changes music vibration of (air) molecules to corresponding electron vibration. A loudspeaker changes electron music vibration to corresponding air molecule vibration. The input and output signals do not have to be the same for psychoacoustic reasons. The objective is not flat frequency response from mic to loudspeaker but from producer's brain to listener's brain. [Lowe and Morgan].
Once in electrical domain we can do a lot of things. [Everitt]. For example sending the sound of a bouzouki using a cable to many meters down into a basement room with tiles so that its sound reverberates there. Then anothe microphone may pickup the reverberant sound and send it back so that it can be added to the dry signal. These rooms are called echo chambers and Columbia studios 2 and 3 had two of them underground.
Most elements below are given by one the main sound engineers at EMI Columbia studio Athens, Stelios Giannakopoulos, Στέλιος Γιαννακοπουλος, who maned the console of either studio 1 or 2 which started operation in 1964.
Some example recordings, some of these by Stelios:
https://m.youtube.com/watch?v=dJi9QpVqubU#fauxfullscreen
https://m.youtube.com/watch?v=k7ZciKttjww
Direct to stereo, recorded by Stelios on either studio 2 or 3.
https://m.youtube.com/watch?v=Ks25u2UKD4E
Απόψε σε θελω - Πλέσσας, Παπαδόπουλος, Μαρινέλα
https://m.youtube.com/watch?v=2FOtKmg-4uI#fauxfullscreen
Έπεφτε βαθιά σιωπή
https://m.youtube.com/watch?v=zGHo8layYic
Αν ειναι η αγάπη αμαρτία
https://m.youtube.com/watch?v=DLtCffIYN0Y
1974? transistor mixing desk?
I am not sure but the first example should have been recorded at studio 3, which started in 1936. The adding desk had mono out. Basic low and high frequency adjustments. Outboard mic amplifiers were the EMI RS61.
This is possibly a recording at the older studio 3 (studio 1936 as Stelios refers to it):
Ευγενικά παιδιά - Xatzidakis arrangement, recorded by Nikos Kanelopoulos
https://m.youtube.com/watch?v=HhYvT4vWf_w&index=8&list=PLeYcXETDsjQUvy6gGIeARr0wO2Ro4O_Y2
And now some elements on how the bouzouki sound is created as the listener's brain perceives it:
Great soul of bouzouki players such as George Zabetas, not interested in money. [αφιερωμα Ζαμπέτας ΕΡΤ - YouTube
Great acoustic instruments. Lack of thump so normally a low cut was not needed.
Great composition and orchestration.
Great acoustics by EMI acoustical engineers. Membrane low frequency absorbers etc some distance from walls. [Gilford - BBC]. Usually 2 bouzoukis, voice 1 and voice 2 were used. At the back of both players was the same acoustic screen in shape of \__/.
Great microphones. Usual distance 20-30cm, 8-12in. Usually Neumann U47 or U48. According to Stelios one U47 was used for both musicians or one for each. In the case of 1 microphone a figure of eight polar response was used, U48, each musician facing the other.
(So for example the fist electron tube in the signal path nearest to Georgos Zabetas was the VF14 inside the Neumann U47 microphone designed by Georg Neumann. The first stage of amplification ie VF14 is the most important defining the signal to noise ratio up to the listener's brain. The VF14 is deliberately supplied by Georg Neumann with a lower hester voltage possibly in the grounds of further increasing the signal to noise ratio. (Of course the acoustic noise level of the studio is most important as well as how strong the message is to the mind of the artist, composer, producer, orchestrator etc). The U47 had impressed the BBC by its high sensitivity ie signal to noise ratio is even now a world prefered mic by top singers, producers.[Charles Leonard]
(The U47 was used at cardioid polar response. According to the BBC report the U47 lacks some bass.[U47 BBC report]. This seems to have been a good thing for some compensation of Fletcher Munson curves.)
Great preamplifiers, V72 for example, electron tube or transistor operating in class A (electrons flowing all the time) [T.S. Gray]. Great passive EMI console EQs.
Some low cut might have been done at the mixing desk. Usually when an offending instrument reached the bouzouki mic.
Great sound engineers. Stelios uses the knowledge of the Fletcher-Munson curves to avoid excessive bass perception to the listener's brain.
The EMI consoles had great low cut, presence boost, high boost or cut filters, all passive.
Just 1 or 2 dB were added at HF, possibly 10KHz to sparkle the sound using the great EMI filters. No presence boost was used for bouzouki.
Great echo chambers. The direct sound was sent by cables to the basement to one of the 2 echo rooms (reverberation chambers). This perhaps explain the big sound from just 2 bouzoukis. There is also the natural delay from the (possibly) Goodmans loudspeaker driven by a Leak electron tube power amplifier sending sound to the room with acoustic delay arriving to the U47 mic inside the echo chsmber. (Tye delay is due to the time sound takes to travel from speaker to mic). In some cases asitional analog tape delay must have been used too. There must have been low cut or high cut to or after echo chambers as they like great midrange.
Great EMI BTR 2 (British Tape Recorders), electron tube reel to reel,recorders. The same EMI types used for Beatles records.
Everything was analog.
It was not uncommon for musicians to work all night at bouzouki night clubs. They would come directly from them early morning. Then sleep on carpet, or top of a piano etc until the recording engineer would arrive.
References:
Communication Engineering - Everitt
https://archive.org/details/CommunicationEngineering
Flat frequency response from brain to brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.E.
Acoustics for radio and television studios - Gilford - BBC
BBC report on Neumann U47
http://downloads.bbc.co.uk/rd/pubs/reports/1954-23.pdf
Applied Electronics - T.S. Gray - MIT
Αφιέρωμα στον Γιωργο Ζαμπέτα - epilogue - εκπομπή αφιερώματα - ΕΡΤ
https://m.youtube.com/watch?v=TCkWoHqiD_4#fauxfullscreen
Excerpts from No tricks were used in Leonard Cohen’s Popular Problems by Charles Leonard (Mail & Guardian: Sept 24, 2014)
(Record Producer) Patrick Leonard has a thing for the U47
https://cohencentric.com/2015/10/17/photo-leonard-cohen-in-recording-studio-with-neumann-u-47-microphone-used-for-popular-problems/
Monday, May 21, 2018
A list of great musicians who could not read notes
Music is a language.
When one asks what the time is, this is not read from paper, it is just said.
And the same happens when we phrase a more poetic line coming from us, our brain, the way we feel at that moment.
One way the master J.S. Bach might have used to compose music would be starting with improvising. (Anna Magdalena's book on her husband Bach). For example he might jam on the organ and if a great prelude had come out he might then write it down.
But there are great musicians who can't write or read notes. In the same same way there are poets who just say it but can't write it or read it.
A list might be as:
Vangelis (see his documentary on YouTube)
Paul Mc Cartney
Manos Hatzidakis (he was referring to printed notes as the paranoid black dots. Perhaps he learned later.)
George Zambetas
...
Example of Zambetas playing bouzouki, (recording EMI Columbia Studios Athens with U47 mics etc)
Sakena's dance - Xarhakos https://m.youtube.com/watch?v=dJi9QpVqubU#fauxfullscreen
Mike Oldfield can play, compose and write (record) not only on tape but paper too.(BBC Oldfield documentary, the making of tubular bells)
Could it be that engineer John F. Kraus used an inductor in series with a resistor connected to the vocal mic of When I Fall in Love - Nat King Cole?
Who knows? Connecting a coil to a resistor and then the resultant across the mic output...
But if he had thought of trying, it would had been very easy for him as he was a great radio ham too. Radio hams are so fluent in electronics.
See nearby euroelectron posts for promising Pleiades experiments listening results.
Such simple and great wave filters are connected directly to the mic output and the resistance part create a very gentle low cut response.
Sch L,R filters can be seen on the datasheet schematic inside the Electro-Voice 642, AKG D1000E etc.
Are they also used inside the the Sennheiser MD421 and MD441?
EQing bass artifacts for a male voice singing in falsetto with improved Pleiades filters
It is done by connecting a low value inductor in series with a resistor and the resultant across the mic's output or voice coil.
Typical values for the excellent Sennheiser MD211 might be 40mH, 140Ω.
This filter at the same time compensates for equal loudness curves and voice effort curves.
See next euroelectron post.
References:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D.P. Lowe and K.F. Morgan - J.S.M.P.E.
http://euroelectron.blogspot.gr/2018/05/connecting-improved-pleiades-filter-to.html
Connecting an improved Pleiades filter to MD211
This is part 3. See nearby euroelectron posts for 1 and 2.
In the last part an inductance of 82mH in series with 140Ω was connected across the excellent MD211 mic's output. Then the usual Altec 4722 input transformer...
Signal path, setup:
Male singing voice (απόψε σε θελω - Marinela) - improved Pleiades filter (L,R) - Pleiades V6 with Altec 4722 input transformer - Sony TC-D5 Pro at XLR mic in - Sennheiser Hd580
The sound is very nice and it was decided not to rotate the 140Ω potentiometer from the 140Ω value assumed by chance.
After a few days, ie today, the setup was turned on again. Sound was great as usual perhaps a bit bass heavy at high registers of voice. (For men using falsetto voice there may be bass artifacts on any mic setup, increasing the distance of directional mics may help as bass is reduced.).
Another 82mH Pleiades filter was lying around near the Pleiades V6 head amp. It was connected after the 85mH inductor. The two inductor together (in parallel) make a turnover of less than 800Hz. The untouched 140Ω resistance creates a very gentle slope.
The sound was phenomenally nice too. Some of the falsetto bass artifacts disappearing. Ordinary non falsetto singing sounds amazing too. Natural.
It is very easy to hear what the L,R Pleiades filter does. By just disconnecting the crocodile clip to one of the resistor's terminals it is out of the circuit. The perceived sound is back to bass heaviness.
Reconnecting the filter bass heaviness disappears. And mid and treble is back.
Adding the extra inductor in parallel to the other inductor reduces some slightly annoying part of mid range.
These filters sound similar to what is done when engaging the HF boost on an Sennheiser MD441. It is not that the treble is boosted, it is more that some mid disappears etc. This is best observed while singing a steady note and playing with the filter.
More interesting experiments are needed to approach the ideal of flat frequency response from producer's brain to listener's brain.
The Pleiades reference at the time being is When I Fall in Love - Nat King Cole.
And the mic reference is the Grampian DP4/L connected to the 140mH input transformer pluged to the Pleiades V6 head amplifier.
For some reason the DP4/L does all that is needed without the need of any EQ rather than the usual 140mH shunt that works very well with its 25Ω voice coil.
Reference:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Resproducing Characteristics - D.P. Lowe and K.F. Morgan - J.S.M.P.S.E.
Using resistance wire for primary transformer winding?
The problem is that the metal used for resistance wire (nickel?) may not sound as good.
Why having a resistive primary winding on a microphone input transformer?
In order to create a gentle bass cut slope a resistance is needed in series with the inductance connected across a mic . See improved Pleiades filters.
It is not the same as having an R is series with the primary winding. Because we do not want to decrease what the primary winding gets. We want to decrease what the mic produces. Just putting an R is series with the primary winding will make the usually 6dB per octave slope but at a higher cutoff frequency.
Using an improved Pleiades filter and then connecting an input transformer is different and it works. Because the primary is connected across L in series with R.
So a distributed resistance is needed. Either resistance wire.
Or a very thin primary wire?
Or using an improved Pleiades filter (L in series with R) across the mic output connected to an ordinary transformer primary as usual.
A typical value of R for a 200-300Ω omnidirectional mic might be 140Ω. A lower value, half perhaps might be used for directional mics as we need to compensate for the proximity effect too in addition to Fletcher-Munson and voice effort curves.
See nearby posts on improved Pleiades filter connected to the Sennheiser MD211.
An interesting, useful lecture on perceived loudness
http://www.physics.mcgill.ca/~guymoore/ph224/notes/lecture13.pdf
Also this interesting lecture.
http://musicweb.ucsd.edu/~trsmyth/loudness175/loudness175_4up.pdf
(A basic corollary of the Fletcher-Muson curves is that increasing the acoustic intensity of a recording increases bass heaviness. Hence the need of low cut or high pass wave filters on production, see Pleiades filters.)
Πως ηχογραφήθηκε το Απόψε σε Θελω, Μαρινέλα, microphones used in a recording at EMI Columbia studios Athens
The song is Απόψε σε Θελω - Πλεσσας, Παπαδοπουλος, Μαρινελα τραγουδι
https://m.youtube.com/watch?v=2FOtKmg-4uI#
Recorded by Stelios Giannakopoulos.
The information below comes from a conversation with the recording engineer Stelios. It is a long time do this is to the best if his memory.
Studio 1 or 2 is used. There are the new ones which were ready by 1964.
On vox there is EMT plate reverb. (Echo chamber too?)
On orchestra the echo chamber.
On Glockenspiel the mic is near the highs. Either Neumann U47 or U67.
There is acoustic screen behind the drums.
It is a direct to stereo recording, all live.
Marinela is singing in the speech room.
Low reverberation time. The studio had membrane absorbers fir low frequency absorption, roofing felt was used.
The echo room or echo chamber adds sweetening.
On vocals (usually Neumann U47) a boost of 2-3dB at 2-3KHz was used to compensate for equal loudness curves (Fletcher-Munson curves). 2dB at 10KHz for brightness.
The clarity of voice is aided by the ingeneous orchestration of composer Plessas leaving frequency spectrum space for the voice.
There is no conspiracy, just public relations
For example the fairy tale "Little Red Ridding Hood".
The philosophy of Epictetous is an antidote.
We have freewill.
Fear or need do not even exist.
Reference:
Enchiridion - Epictetous
https://www.stmarys-ca.edu/sites/default/files/attachments/files/Enchiridion.pdf
Sunday, May 20, 2018
Η ιστορία του Σταλιά Σταλιά - Ζαμπέτας, Μαρινελα
Στο 7:58:
Μηχανή του χρόνου - Ζαμπέτας
https://m.youtube.com/watch?v=2qlSs4TXIKY#fauxfullscreen
A photo of EMI Columbia Athens studios, μια φωτογραφια του στουντιο της Κολουμπια
At 12:57
Η μηχανή του χρόνου - αφιέρωμα στον Ζαμπέτα
https://m.youtube.com/watch?v=2qlSs4TXIKY#fauxfullscreen
A nice example of the interval major 7th, ενα όμορφο παραδειγμα του διαστήματος μεγάλης έβδομης
Αν ειναι η Αγάπη αμαρτία - Πλέσσας, Λυμπεροπουλος, Βανου
https://m.youtube.com/watch?v=DLtCffIYN0Y
It takes time place at 1 minute and 20 seconds.
Bass is D flat. Melody is C.
Some other instrument or voice is playing the third from bass, ie F.
Bibliography:
Bach Bass Rules:
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf
Another interesting recording from EMI Columbia Athens
Composer is Mimis Plessas, Μιμης Πλεσσας. Singer is Jenny Vanou, Τζενη Βάνου.
Possible year 1974.
Αν ειναι η Αγάπη αμαρτία - Plessas, Liberopoulos, Vanou
https://m.youtube.com/watch?v=DLtCffIYN0Y
The importance of the acoustic backing track intensity for singing in tune
It may be a low acoustic intensity.
You are the judge.
The references that contain the secret are:
Sound and Hearing - S.S. Stevens, Fred Warshofsky - Life Science Series
Making Records - Phil Ramone
Ήταν η Τζενη Βάνου Κοντραλτο;
Τι απίστευτη φωνη.
https://m.youtube.com/watch?v=DLtCffIYN0Y
Στο τραγουδι του Μιμη Πλεσσα, Αν ειναι η αγάπη αμαρτία, στο σημείο (για) σένανε μου λένε στο (για) η νότα ειναι χαμηλό Φα.
Ειναι απ οτι φαινεται contralto οπως πχ. Cher, Gloria Estefan, Toni Braxton κτλ.
Ωραιο ειναι γυναίκες να τραγουδούν χαμηλές νοτες οι οποίες ετςι και αλλιώς ειναι μια οκτάβα πανω απο τις αντρικές.
Ακούγονται οι χαμηλές νοτες αβίαστα αφου ειναι το χαμηλό γυναικείο ρεζιστρο.
Και ειναι πεντακάθαρος o ήχος αφου η συχνοτητα ειναι διπλάσια απο την αντρική.
Οιίδιες συχνότητες για να τραγουδισει ένας άντρας ειναι στο υψηλό του ρεζιστρο. Παλι ακούγονται ομως πανέμορφα αφου ειναι ίδια συχνοτητα και σε μια ξεκάθαρη περιοχή για το ανθρώπινο αυτί. Πχ. Careless Wisper - George Michael.
Η Τζένη Βανου ειναι καρφί στις νοτες.
Θα άκουγε σωστά. Και αυτο δεν σημαίνει τι έκανε μονο εκεινη αλλα και οι γυρω της που θα τις έδειναν backing track στην σωστή ιςως χαμηλή ένταση οπου ο εγκεφαλος ακούει σωστά τις νοτες.
Ειναι τρελό ξεκάρφωμα που το βιβλίο που το αναφέρει αυτο ειναι ξεχασμένο σε τόσες Ελληνικές η ξένες βιβλιοθήκες. Ο τόμος Ηχος και Ακοη της εγκυκλοπαίδειας Λάιφ, μεταφραση του ιατρού Μανου Τιερη απο το αγγλικό κείμενο του S.S. Stevens, διευθυντή ψυχοφυσικης του πανεπιςτημιου Χαρβαρντ και του Fred Warshofsky.
Αναφορά για το ποσο σημαντικη ειναι η ακουστική στάθμη για να τραγουδάμε σωστά (αφαλτςα) υπάρχει καπου στην αρχή του βιβλίου του μουσικού παραγωγου Phil Ramone. Πολυ γνωστό κοματι που παρήγαγε το Girl from Ipanema - Arstud Gilberto.
Πηγες:
https://m.youtube.com/watch?v=DLtCffIYN0Y
https://en.m.wikipedia.org/wiki/Contralto
https://en.m.wikipedia.org/wiki/List_of_contraltos_in_non-classical_music
Ηχος και Ακοη - Εγκυκλοπαιδια Λάιφ - Η επίδραση της σκέψεως - σελίδα 77
Making Records - Phil Ramone
H Τζένη Βάνου live με μικρόφωνα AKG
Βάζοντας στο Google Τζένη Βάνου με μικροφωνο, στις εικόνες, ασπρόμαυρες φωτογραφίες, φαινονται τα δυναμικά (κινητού πηνιου μεςα σε μαγνητικό πεδίο) μικρόφωνα της AKG.
Συγκεκριμένα πιθανότατα το D1000 και το D190.
To D1000 εχει φανταστικό φίλτρο με διακόπτη 2 θεςεων πανω του για να κόβει τα λασπώδη μπάσα απο το φαινόμενο εγκυτητας των κατευθυντικων μικροφώνων. Επισεις βοηθάει η απόκριση συχνότητας να ειναι ισορροπημένη στον εγκεφαλο του ακροατή αντισταθμίζοντας τις ισοφωνικες καμπύλες οπως και τις voice effort curves.
Εσωτερικά το D1000 εχει συνδεμένο με το κινητό πηνιο, μια αυτεπαγωγη (πηνίο) σε σειρα με μια αντίσταση. Οτι μαθαίνουμε στην φυσική του σχολείου στον μαγνητισμό. Η αντίδραση του πηνιου σε Ωμ αύξανει με τη συχνοτητα. Ο νόμος της επαγωγης του Faraday. H τάση στα άκρα ενος πηνιου ειναι αναλογη του ρυθμού μεταβολής του μαγνητικού πηνιου που διαπερνά το πηνιο. Στην εδώ περιπτωςη έχουμε να κάνουνε με αυτεπαγωγη αφου το ίδιο το πηνιο παράγει το μαγνητικό πεδίο που το διαπερνά. Και ολα αυτα φυσικά γίνονται αφου το κινητό πηνιο ενος μικροφωνόυ μετατρέπει την κινηςη μορίων αέρα απο την τραγουδίστρια σε αντίστοιχη κινηςη ηλεκτρονίων μεςα σε ηλεκτικους αγωγούς σύρματα η καλώδια, αντιστάσεις πηνια, ενιςχυτες με σωλήνες ηλεκρονιων, τρανζίστορ κτλ.
Δείτε επισεις improvements to the Pleiades filters.
Όσοι ειχαν την ευκαιρία να ακούσουν live την απίστευτη αυτη τραγουδηστρια θα το απολάμβαναν.
Φανταστικά μικρόφωνα ειναι τα παντοκατευθυντικα κινητού πηνιου τα οποία δεν έχουν φαινόμενο εγγύτητας.
Για παραδειγμα το Electro-Voice 635a, το Sennheiser MD211. MD21 κτλ.
Μπορεί κανεις να ακούσει το 635a σε TV live του Dumb Blonde - Dolly Parton
Στις ηχογραφήσεις studio των περισσότερων τραγουδιστών της χρυσής εποχής του Ελληνικου τραγουδιού στην Κολουμπια EMI στον Περισσό χρησιμοποιούνταν το U47 μικροφωνο της Neumann με ηλεκτροστατικη (πυκνωτικα) κάψα και ενισχυτη μεςα στο μικροφωνο με σωληνα ηλεκτρονίων την VF14
Δείτε επισεις τον ενισχυτη (ανοιχτού κώδικα) Pleiades V6 με σωληνα ηλεκρονιων που ειναι βασισμένος στον ενισχυτη τοθ U47 με την σημαντικη απλοποίηση οτι μπορεί να λειτουργήσει με μπαταρία. Μπορεί να συνδεθεί με οποιαδήποτε μικροφωνο οπως και κινητού πηνιου. Ο Λευτέρης είχε την ιδέα να φτιαχτεί ένας εξωτερικός ενισχυτής σαν του U47. Και η Ηλιανα είχε την έμπνευση να ελευθερώνονται τα ηλεκτρόνια με πηγη πολωςης μια θετική τάση. Ο Παναγιώτης εδωςε ενα σχηματικό ενισχυτη που να εχει μονο ενα JFET και μια αντίσταση.
Πηγες:
Φυσική - Μαζη
AKG D1000E datasheet
Ευθεία απόκριση συχνότητας απο τον εγκεφαλο του παραγωγου στον εγκεφαλο του ακροατή, Sound Picture Recording and Reproducing Characteristics - Lowe And Morgan - J.S.M.P.S.E.
Microphones - Lou Burroughs
Electronics - A systems approach - Neil Storey
The Feynman Lectures in Physics
Neumann U47 schematic
Pleiadss V6 schematic
We do not learn music, music teaches us
Same with electronics, physics, art etc.
Like a mountain or the sea teaching us.
(We also learn from those who know.
We teach ourselves.)
Nature teaching us.
Την μουσική δεν την μαθαίνουμε, αυτη διδάσκει εμάς
Οπως ενα βουνό μας διδάσκει, η η θαλαςςα.
Και έχουν τοςα πολλά να μας μάθουν.
(Μαθαίνουμε και απο όσους ξέρουν.
Μαθαίνουμε απο τον εαυτό μας.)
Saturday, May 19, 2018
Variable Pleiades Microphone Wave Filter with 2 degrees of Freedom
Could it be a box with 2 rotary controls? Or 4 including a variable slope CR high cut wave filter by selecting different values of shut C in series with a variable R.
Let's describe the low cut section. The high cut section can be implemented by analogy.
For the low cut section there can be 2 controls. One for the inductance L and one for the resistance R.
The schematic is L in series with R and the resultant connected across the mic's output or voice coil.
Many inductors can be connected to a rotary switch. So with one hand the turnover frequency is adjusted while the other hand rotating the variable resistor adjusts for slope while trying to obtain the desired acoustic result.
Or switching in inductors corresponding to 100Hz, 200Hz, 400Hz in all permissible binary combinations, 8 for example using 3 inductors giving 0Hz to 700Hz in steps of 100Hz.
Or having an XLR female socket and inserting Pleiades barrel inductor filters on top of each other.
Pleiades inductor wave filters have the property that if one XLR adapter is x Hz and the other is y Hz, the resultant of connecting one barrel after the other (ie inductors in parallel), is a frequency turnover of (x+y) Hz. See older euroelectro posts on binary combinations.
See also close posts including one on connecting a fixed LR Pleiades wave filter to the Sennheiser MD211 output before connecting to the Pleiades V6 head amplifier (electron tube, battery powered).
Can the variable resistor be inside the XLR adaptor low cut filter so that the slope is variable as in the excellent Sennheiser MD421, MD441 microphones?
See next post on improved Pleiades wave filters.
http://euroelectron.blogspot.gr/2018/05/improved-pleiades-filters.html
Can the variable resistor be an elegant rotary dial around the circumference of the barrel adaptor. Or perhaps half of the adaptor being able the rotate against the other half while adjusting for close to flat producer's brain to listener's brain frequency response.
Improved Pleiades Filters
Improved Pleiades microphone filters for flat frequency response from producer's brain to listener's brain.
This update to the Pleiades wave filter is including a resistor in series with the inductor coil.
The resulting 2 terminals are then connected to pins 2 and 3 of live and return of the mic.
The inclusion of the resistor changes the low cut or high pass curve slope to a gentler one.
R can be variable for any slope.
Both passive components can fit inside a Neutrik XLR barrel adaptor.
Examples of microphones using a resistor, inductor wavefilter are the AKG D1000, Electro-Voice 642.
A typical L, R combination for close mic singing with the Sennheiser MD211 can be 85mH in series with 140Ω. A more symmetrical or balanced arrangement can be 70Ω in series with 85mH in series with 70Ω.
A 85mH, 140mH Pleiades wave filter has been tested in the following setup:
Male singing voice, usually soft to normal - MD211 at 2-4in - Pleiades wave filter (85mH,140Ω) - Sony TC-D5 Pro XLR mic in - Sennheiser HD 580
The sound is brilliant with no bass heaviness but full body.
For more detail and less hiss the Pleiades V6 booster head amp is used in the following signal path:
Male singing voice - MD211 - Pleiades (85mH,140Ω) - Pleiades V6 with Altec 4722 input trasformer - Sony TC-D5 XLR mic in - HD 580
Great natural sound.
Perhaps it may be a good idea to incorporate a variable resistor inside the an XLR barrel adaptor making the slope variable as on the brilliant Sennheiser MD421, MD441 microphones.
Can the variable resistor be an elegant rotary dial around the circumference of the barrel adaptor? Or perhaps half of the adaptor being able the rotate against the other half (with lock option) while adjusting for close to flat producer's brain to listener's brain frequency response.
References:
Electro-Voice 642 datasheet at www.outant.org
Flat frequency response from brain to brain, Sound Picture Recording and Reproducing Characteristics - D.P. Lowe and K.F. Morgan - J.S.M.P.S.E.
http://euroelectron.blogspot.gr/2018/05/a-resistor-in-series-with-inductor.html
How would the Electro-Voice 642 microphone sound connected to the Pleiades V6 head amp
On this video the Electro -Voice 642 is liked as much as a Neumann U47.
The Electro Voice 642 - Audio Master - YouTube
https://m.youtube.com/watch?v=Rj71IFMKW7c
The 642 has a 2 position low cut, one is with a gentle slope using an inductor and resistor is series. The L R combination is connected to the 50Ω output, see datasheet schematic.
Currently the Pleiades experiments are on Sennheiser MD221 connected to such as filter and the sound for singing male voice is amazing. The Pleiades V6 head amp is used. See a nearby in time euroelectron post.
References:
Electro-Voice 642 datasheet from the Coutant website
http://www.coutant.org/data/642.pdf
http://euroelectron.blogspot.gr/2018/05/a-resistor-in-series-with-inductor.html
Friday, May 18, 2018
The great sound of bouzouki as recorded at EMI Columbia Athens studios
Some examples:
https://m.youtube.com/watch?v=Ks25u2UKD4E#fauxfullscreen
https://m.youtube.com/watch?v=dJi9QpVqubU
Great acoustics possibly with membrane bass absorbers (see other posts), each instrument separated with tall absorbing screens, Neumann U47 microphones, echo chambers at the basement, many recordings were done direct mix to mono or stereo, electron tube equipment, preamplifiers, analog tape recorders etc.
A resistor in series with an inductor connected to the Sennheiser MD211 omnidirectional microphone
L=85mH
R=140Ω
(Later addition. The idea of L in series with R and also be seen on the academy award winning Electro-Voice 642 as well as on the AKG D1000E).
This is continued from:
http://euroelectron.blogspot.gr/2018/05/primary-transformer-inductance-for.html
This is on further experiments in order to get as much flat frequency response from producer's brain to listener's brain from the amazing Sennheiser MD211 N, one of the best microphones ever made. It even is a mic with no sibilant problem while having amazing treble detail no mater how close it is used.
Signal path, setup:
Male voice singing bass register the song (Stalia Stalia - Marinela) - Sennheiser MD211 N at 2-4in from mouth - inductor in series with a 300Ω potentiometer - Pleiades V6 head amp with input transformer the Altec 4722 - Sony TC-D5 Pro at XLR mic in - Sennheiser HD580 headphones
Paying attention to how important phase is, (in this case from positive presure increase to the mic to positive presure increase from headphones) a phase reversal XLR adaptor is used before entering the Sony TC-D5 Pro in all these experiments as this particular example of TC-D5 phase reverses.
Before connecting the LR filter the following listening tests were done.
The MD211 connected to Pleiades V6 with the Sowter 260mH input transformer. Great sound but there is a sense that it can be even more natural. HF and mid is great but there is some sense of low mid missing even if there might be a slight overall bass heaviness.
The current Pleiades reference Grampian DP4/L (25Ω) omnidirectional mic connected to Pleiades V6 with the usual 140mH (primary inductance) transformer. Amazing sound. Full body and natural. Everything is there, bass, mid, HF detail. Smooth. Clear as life.
Back to the first test. Beautiful but still this sense of something missing or can be improved.
Next test is the MD211 connected to Pleiades V6 but this time with the Altec 4722 mic input transformer. Big sound, but too much bass heavy. Apart masking lack of mid or treble. This is because the primary input inductance is 3H. The following tests are done while keeping the Altec 4722 and inserting Pleiades wave filters in parallel with the mic output (or transformer input) in order to reduce the brain perceived bass heaviness.[Lowe and Morgan]
A Pleiades XLR barrel inductor filter of 330mH was connected. This gives a -3db point at about 100Hz when a mic of 200Ω is used. (The impedance of the MD211 used measures 260Ω). Sound is much better much more clear but still somewhat bass heavy.
Another Pleiades filter of 330mH is connected after the previous filter. Resultant shunt inductance is now half or 160mH and cutoff is 200Hz. Clear sound but bass light. The decision or idea comes to insert a series resistor and a filter of higher cutoff.
So a 300Ω log potentiometer is connected using 2 of its terminals to a male XLR through cable crocodile clips so that the inductor that will be inserted in the XLR socket will be in series with R. The resultant was connected to the mic cable 2,3 ie live,return. Following the fashion of the AKG D1000E previous Pleiades experiments an inductor of 85mH was inserted. This theoretically gives about a 385Hz turnover point with a 200Ω output impedance mic. The variable resistor was left to a random position, aproximately 140Ω. The sound is brilliant. Full body or big sound with no bass heaviness, great mid and treble. Very clear and natural.
The measured value of the potentiometer is 140Ω or 145Ω.
The value of this resistance in series adjusts the slope of the low cut curve.
It was easily decided not even to turn the potentiometer for the time being.
This is the schematic of the Pleiades V6 low noise head amp used. C is 22nF, Rag anode to grid biasing resistor is 6MΩ (Pleiades bias) for freeing the electrons. There is an aproximately 12Ω series to heater supply resistor (not shown) such that the anode current is reduced to typically 60μA.
References:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.E.
The song used for the test, sung with male voice:
Stalia Stalia - Marinela
https://m.youtube.com/watch?v=Ks25u2UKD4E#fauxfullscreen
Pleiades V6 schematic or description - euroelectron
Electro-Voice 642
http://www.coutant.org/data/642.pdf
If electron tubes, transistors, JFETs are flat from 0Hz to a high frequency why do amplifiers have low and high frequency roll off?
This is due to the surrounding components.
For example capacitors in series reduce bass frequencies.
Capacitors in parallel reduce treble or high freiencies. It makes sense since a capacitor tries to keep the voltage across its terminals constant. There may be stray capacitances, for example a cable and the nearby metal chassis making the plates of a capacitor. Or the conductors of a cable etc.
Inductors in parallel with the signal cut bass.
Inductors in series with the signal cut treble.
The cut off frequency of any case is determined by the value of C or L and the resistance next to them.
R and C defines a time constant. A high R in series or high output resistance will charge a large capacitor slower. In fact in physics or nature R x C makes t or time. 1Ωμ x 1 Farad = 1 second.
So a high output impedance driving a high shunt capacitance will make a duller sound as the cutoff is decreased.
These are called RL filters.
A similar interaction exists between R and L. In Physics or rather nature inductance L devided by resistance R make time.
An inductor is like a mass trying to keep it's velocity constant. A coil or inductor tries to keep the current through it constant or reacts to any change like a mass. This is why treble is cut when an inductor is connected in series.
For example a door which has mass can it be moved back and forth to quickly. Frequency response drops the higher the frequency we want to make the door oscillate. We are the driving source with a certain output impedance. The impedance of the door changes we frequency and we can feel it. with frequency.
For a similar reason bass is cut when it is connected in parallel. The lower the frequency the more a short circuit it is as its reactance in ohms goes down.
When an inductor or a transformer winding is connected in parallel with a real voltage source which has a finite output impedance a potential devided is formed. The low impedance of the inductance at LF creates a greater voltage drop at the output of a mic, electron tube etc. the cutoff frequency depends on R, L and can be anything eg. 3Hz, 40Hz, 300Hz. This can be useful as it can remove bass heaviness making a mic sound flat in frequency response from producer's brain to listers brain. See Pleiades filters. See also Lowe, Morgan paper.
The cutoff frequency depends on R and L. The higher the R and the lower the L the more bass is cut or more high is passed ie the cutoff frequency is raised.
References, bibliography:
Electronics, a systems approach - Neil Storey
Applied Electrinics - T.S. Gray - MIT
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reprocucing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.E.
Great information on the CK28 capsule and AKG C26, C28 by the BBC RD
This is the URL of the BBC research department report:
http://downloads.bbc.co.uk/rd/pubs/reports/1961-12.pdf
Wireless World article on the Neumann M49
This is the reference:
F.W.O. Bauch, "New High-Grade Condenser Microphone", Wireless World, No. 59, March 1953, pp 111-114
A list of BBC research department reports
This is the url:
http://downloads.bbc.co.uk/rd/pubs/reports/bbc-rd-report-list.pdf
The BBC report on the Neumann U47
This BBC research department report includes one if the most beautiful schematics of U47.
Report No. M.020
Serial No. 1954/23
http://downloads.bbc.co.uk/rd/pubs/reports/1954-23.pdf
The BBC report on the AKG C12
This is the url on the AKG C12 condenser microphone report by the BBC research department:
Report No. M.026
Serial No. 1954/41
http://downloads.bbc.co.uk/rd/pubs/reports/1954-41.pdf
Thursday, May 17, 2018
Another world class sound engineering text book
Motion Picture Sound Engineering
https://pdfs.semanticscholar.org/a1c9/e0faefa9c70b636ca49283a21293c79c2646.pdf
Designers of world class EQs, wave filters must have been using this or the equally excellent:
Elements of Sound Recording - Frayne, Wolfe
These 2 books by the way were favorites by Mikes Psalidas, electronic engineer who designed the electron tube adding (mixing) console for Finos Films in Athens and one for Vangelis.
So possibly at least 2 oscars, Zorbas, Never on Sunday. Did Vangelis used this console for Chariots of Fire?
The coils or inductors for voice effort EQ etc were wound by his friend Tasos Fousekis at a basement in Syntagma square (opposite the parliament) that part of a known airline company offices.
A great generous man.
Sources:
Conversation with Mikes Psakidas
Conversation with Tasos Fousekis
Οι Οκτώ Κύκλοι (Eight Rounds) - Τάσος Φουσέκης - unpublished autobiography
Comparison of Sennheiser MD211 to Sony TC-D5 Pro direct or through the Pleiades V6
The Pleiades V6 booster is open source as everything Pleiades.
A very important reference for Pleiades experiments is the recording of When I Fall in Love - Nat King Cole.
Below is the first signal path:
Sennheiser MD211 N - Sony TC-D5 Pro mic XLR input - Sennheiser HD580
All the above equipment are world class, on the league of the best mankind has made.
Yet the sound to listener's brain leaves so much to be desired. So if in a hurry one may by accident dismiss a singer, a world class mic, a world class analog preamp and recorder.
The sound as perceived by the listener's brain is bass heavy plus giving the impression of a tubby quality if the acoustics have low frequency reverberation. The direct and reverb bass heaviness masks the mid and high frequency detail. If the singer sings softly the gain on the TC-D5 has to be set near max so there is hiss too. This hiss is possibly not from the microphone thermal noise. If one sings very close to the mic the reverb almost disappears but still the sound is bass heavy even if MD211 is an omni mic and has no proximity effect. There is still hiss.
When the Pleiades V6 booster electron tube battery powered amplifier is inserted between the two equipment the sound immediately becomes big, clear, natural, with no hiss. Almost no hiss.
As if there is no electronics involved, just acoustic perception of the singing voice.
The difference is that by increasing the headphones volume control one can achieve a louder acoustic intensity for a given acoustic intensity voice than real life.
The world class MD211, TC-D5, HD580 headphones shine in their own right.
Signal path, setup:
(Test includes male voice singing When I Fall in Love - Young, Heyman)
Male singing voice - MD211 N - Pleiades V6 with Sowter 9126g 260mH input transformer - TC-D5 Pro mic XLR input - HD580 - listener
(The Sowter 9126g is a programable (user adjustable) inductance input transformer. See the euroelectron post with title Primary Transformer Inductance for the Sennheiser MD211).
Why such a difference?
One reason is that the inductance of the primary of the input transformer is 260mH which compensates for the bass heaviness and gives flat frequency response from singer's brain to listener's brain. [Lowe, Morgan]
260 millihenries is suited for this particular microphone at a given singing application. Another microphone would like to see another input transformer primary inductance, L, see nearby euroelectron posts. Inductance is not to be confused with impedance. Impedance of an inductor Z=ω times L, ω=2 times π times frequency, π is the ratio of circumference to diameter of any circle ie the Πυθαγόρας π or 3.14.....
(Note: Why does a shunt inductance reduce bass? Because the output impedance of the mic and L form a potential devider. At LF where the impedance of the inductor is decreasing it loads the mic and there is more voltage from across its impedance. Therefore the voltage output at the mic's terminals themselves drops).
A second reason is that the EF183 electron tube at such conditions is ultra low noise and the subtlest information that the mic gives passes through, is amplified. The gain on the excellent TC-D5 can be substantially decreased so it's thermal noise disappears. The recording level potentiometer can be set to 2-3 out of 10 instead of to 9-10 out of 10. The world class HD580 headphones are driven in a brilliant natural way.
Another reason may be the generous driving of the analog TC-D5 stages. At peaks there may be gradual peak limiting increasing average level and subjective level. [Hamm]. How much this effect takes place should be normally adjusted by the recording level knob.
Pleiades V6 schematic.
The coupling capacitor is 22nF and the anode to grid bias resistor is 6MΩ.
References:
Flat frequency response curve from brain to brain, Sound Picture Recording and Reproducing Characteristics - D. P. Loye and K.F. Morgan - J.S.M.P.E
Pleiades V6 Schematic
Tubes vs Transistors (vs operational amplifiers), is there an audible difference? - Russel O. Hamm - JAES
Comparing Microphones
It is not as easy as it seems.
Each microphone like to be terminated by or likes to see a particular input tranformer primary winding inductance so that it approximates the ideal of flat frequency response from producer's brain to listener's brain.
The primary inductance seems to have a big influence on the end result as it controls whether the sound will be bass heavy or bass light according to what is the acoustic intensity when recording and what is the acoustic intensity when reproducing. So a specific value of inductance is a guideline.
For example the Grampian DP4/L (25Ω) sounds so good terminated by 140mH that it may be thought it sounds slightly more detailed than real life. More detail is possibly because we usually reproduce a voice at a higher acoustic intensity level than the original voice acoustic level. Compared to all mics tested so far the Grampian is the most natural in every respect but it has to be terminated with 140mH and preamplified by a ultra low noise booster amplifier such as the Pleiades V6.
The Sennheiser MD211 prefers to see an inductance of the order of 260mH in order to approach the ideal of flat frequency response from producer's brain the listener's brain. [Lowe, Morgan]
The same model of a mic but with a double output impedance should like to see a double optimum inductance.
Directional mics should like to see a lower inductance for compensation of the proximity effect. (Pleiades wave filters). But there is danger of overloading the core and perhaps an inductor in series with a resistor (improved Pleiades wave filter) connected shunt (in parallel) to the voice coil should be used as is done on the AKG D1000.
The inductance values suggested are rough guilines. Another reason for this is that there is already some low cut effect due to the intersection of the V6 booster amp electron tube anode resistance with the output transformer primary inductance.
Signal path, setup:
Male voice singing When I Fall in Love - microphone - Pleiades V6 front end booster amp jig with octal base input transformer - Sony TC-D5 Pro used as followup preamplifier - Sennheiser HD-580
Reference:
Brain to brain flat frequency response curve, Sound Picture Recording and Reproducing Characteristics - Loye, Morgan - Journal of the Society of Motion Pictures Sound Engineers
Wednesday, May 16, 2018
Anybody can sing or play in tune
Perhaps all that is needed is (flight hours or) singing hours and listening correctly.
By listening correctly we may mean a very low acoustic intensity level of the backing track, karaoke track, radio playing etc.
Or the correct acoustic intensity. See Phil Ramone.
Pitch perception depends on acoustic stimulus intensity.
See page 77 of possibky the best book ever written on sound and hearing, by S.S. Stevens, the founder of Harvard Univeristy Psychophysics lab.
It is great fun that this book can be found in many typical households.
References:
Sound and Hearing - Stevens, Warshopsky - Life Science Series - chapter: The Mind's Influence
Making records - Phil Ramone
Is there a programable plugin?
For example a computer sends an impulse signal or a frequency sweep to the equipment we wish to emulate and the impulse response or sweep response is recorded.
Same for emulating the reverb of a room.
In a few words the theory is:
Assuming a system is linear. In practice no system in nature is linear.
By the uncertainty principle in signals, the shorter a pulse the more bandwidth it contains.
A Fourier transform transforms from time domain to frequency domain. For example a sine wave looks like a sinewave in time domain. But in frequency domain it is just a point indicating the frequency.
A short duration sinewave is not a point in frequency domain as the shorter it is the more uncertain we are to its frequency. So in frequency domain it is curve with peak its frequency.
An impulse is a signal with infinite amplitude and infinitesimal duration so that it still has a finite area or energy in time domain.
The Fourier transform of the impulse is a straight line from minus infinite frequency to infinite frequency.
A realistic impulse approximation contains a large bandwidth. For example clapping hands once in front of a piano (this damper release pedal pressed) sets all strings of all available frequencies in sympathetic vibration. See Waves - Barkeley Physics Couse.
If the impulse output of a linear system is recorded and then the Fourier transform taken we receive the frequency response of the system.
The impulse response is unique for each system or characterizes it.
From it the behavior to any signal can be computed using the convolution theorem etc.
Is this a way plug ins operate?
Nice or ingenious as they may be they are not the real thing and consume energy.
It is great that plug ins are beginning to be used only when really needed.
For example why should one use a plug in to a mic chain when most of what is unwanted from a mic can be removed by connecting an inductor, or inductor capacitor combination, or inductor resistance combination. See RCA 77DX schematic, Electro-Voice RE-15 schematic, Shure SM7 schematic, EMI RS106A, Pleiades filter. They are all passive, no energy consuming, they just remove the signal energy that is not needed like photograohy filters. They can be directly connected to a mic getting rid of unwanted bass heaviness to listener's brain before it gets and compromises the rest of the analog stages. Wave filters can be balanced. [Elements of Sound Recording].
Why should one carry something unwanted even to the digital domain and not eliminate it at source? Plug ins are great. Why not giving them the best source signal?
Now a little on echo chambers.
They should be fun to make by converting an unwanted relatively small room. See for example Frank Laico interview on the Columbia church studio in New York and the small church store room used for reverb. Also installing drain pipes etc for diffusion as can be seen on BBC and Abbey Road studios photos, see references on other euroelectron posts.
Now a little on singing in tune. A singer should be in tune if the right sound acoustic intensity of the backing track is heard. See next euroelectron post. [Stevens], [Ramone].
Plug ins must be a great invention.
It is great that we are beginning using them rather than them using us.
Reference:
Introduction to System Dynamics - Shearer, Murphy, Richardson - Addison Wesley
Waves - Berkeley Physics Course, Vol.3
Anatomy of a Session - Frank Laico AES interview - YouTube
Sound and Hearing - S.S. Stevens, Warshofsky - Life Science Series
Making Records - Phil Ramone
Elements of Sound Recording - Frayne, Wolfe
Information Theory and Noise - Pettifer lectures at Warwick University Physics Department
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