Sunday, January 27, 2019
Phantom powered electron tube microphone booster amplifier?
At your risk. Take all safety precautions before using any voltage.
Referring to Pleiades V6 schematic...
Today the V6 schematic was redrawn on the beach just before sunset. The gentle sea waves kept erasing the bottom battery heater and anode supply part..
So it was decided to just take a centre tap from output transformer secondary (ie phantom voltage supply) and connecting it as Vb to output transformer primary which then feeds the anode.
And then also connecting a series resistor to the phantom voltage supply and feed a direct heater filament electron tube cathode with 1.5V or less. Filament heaters of hearing aid tubes require just 10mA. And of some 7 pin subminiature tubes just 50mA. See previous posts.
The heater dropping resistor could if needed be used for bias as on the Neumann U47 schematic.
The cathode can be connected to ground or through such part of dropping resistor.
Pleiades bias can be used from anode to grid but it should not be really needed as 48V is plenty to create even large anode current which should not be needed anyway.
So to summarize:
An EF14 electron tube underheated as VF14 is on Neumann U47 could be heater powered by a say 3.7V battery (use always a fuse in series with a battery for safety) and then the anode powered by phantom power.
Of if phantom power current capability allows getting both heater and anode power from phantom power.
Grid at space potential can be tried too (see older posts). It should be fun.
(Would this arrangement be useful for moving coil, ribbon or printed coil ribbon mics stepped up by input transformer, electret or non electret condenser capsules, crystal mics, Olson grid electronic microphone etc?)
Saturday, January 26, 2019
Self Composing Orchestra
If Vangelis is right in saying that music comes from somewhere or is already there and all we have to do is just be ready...
Is it possible...
For orchestra musicians to just play (compose) without the need of a score (paranoid black dots - Hatzidakis)? This does not mean anarchy. On the contrary the musicians should be at or greater level than a conductor having for example understood and use in practice Bach Bass Rules - Bach, Neidt.
To record such orchestra near a quiet outdoor places, eg near forest with a stereo printed ribbon microphone such as Fostex? Possibly the only microphones delicate night to extract detail yet urged enough for ribbons to survive outdoors.
And feeding the stereo mic to an analog Uher reel to reel such as Uher 4200 stereo battery powered?
It is still is hard work. Carrying the mic, the 2-3Kg recorder the BASF 1/4 tape, instruments, chairs, sesame snacks or whatever healthy...
How would it sound like?
It could be any instruments.
References:
Interviews of Vangelis in Hellenic language magazines, see older post.
Bach Bass Rules - Bach, Niedt
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf
P.S.
Would Vangelis Papathanasiou music research foundation assist in this direction?
P.S.2
If it won't sound right it can always be done with a mic for each instrument.
Monday, January 21, 2019
Does the Beyerdynamic M260 handheld ribbon microphone use same back loading principle as M88or AKG D12, D20, D25 etc?
Xaudia has some very interesting photos of the inside:
http://xaudiaelektrik.blogspot.com/2014/06/whats-inside-beyerdynamic-m260.html
It looks very similar to inside the M88. In the M88 were found many multithreaded ropes inside the long tube.
So is M260 using the same principle as AKG D20 of terminating the back of the diaphragm by a transmitiin line having the same characteristic impedance as the diaphragm impedance so that diaphragm sees an infinite length transmission line? (See previous posts on the AKG parent). No standing waves are formed and the frequency response is very smooth.
How about the spiral ribbon Fostex M55RP?
Did Beyer invent the proximity compensating transformer?
It is mentioned in the specs that a low cut is in the mic.
http://recordinghacks.com/pdf/beyerdynamic/M260_DB_E_A3.pdf
Is it done by a lower inductance transformer or an RL circuit in parallel with transformer primary?
Grampian GR ribbons use a lower primary inductamce ribbon transformer than for example Coles 4038. So Grampians sound more bright. (See a previous post for measured primary inductance).
No matter what, all these were done before Pleiades filters or Pleiades transfomers.
The nice thing about Pleiades filters is that the inductor or resistor etc can fit inside an XLR female to male adapter and therefore the filter be used with any mic. Even omnidirectional moving coil microphones to compensate for Fletcher-Munson or voice effort curves so that bass heaviness is reduced.
Pleiades experience has showed so far that a low inductance primary may not sound as good as an R,L filter and then a normal inductance primary. Is this a reason the M260.80 has a reputation of being slightly less great than the M260?
How would the M260.80 sound terminated externally (ie to the secondary of the M260 transformer) by a Pleiades (130Ω,40mH) filter?
Index of microphone manuals from berklee.edu
https://mpe.berklee.edu/documents/studio/manuals/microphone/
Sunday, January 20, 2019
Shouldn't there be a website telling which mic was used for such and such song?
For example:
Back to Black - Amy Winehouse
RCA 77DX
When I Fall in Love - Nat King Cole
?
Sweet Harmony - Beloved
?
Saturday, January 19, 2019
Can microphones improve over time, why do same batch mics may sound different etc
This may be all subjective. But it may all be objective too.
It is not only genes but it's is the environment too.
For example moving coil microphones attract magnetic dust.
Maybe too little may raise the reasonan frequency and make the mic sound less bass bass heavy. But past a point it may be a bad thing.
(For explanation of how magnetic dust can be removed from the membrane see Lou Burroughs book on Microphones).
Yesterday 2 Sennheiser MD21 had arrived from the same eBay seller.
The Grundig gold one sounds like gold. Amazing in every respect. Connected to a Pleiades 130Ω,40mH gentle low cut filter (to reduce brain perceived bass heaviness) it sounds like someone is talking or singing next to you.
The Telefunken one sounds like a broken telephone. Initiating the nightmare of opening it up...
Everything was tried to be done under a big magnifying glass.
Wearing googles to protect eyes from metal tiny particles, the 2 pins where gently hammered in.
The metal brace was removed.
Then the metal grill was removed.
Then a cloth was revealed.
There were big iron fillings passing trough the pores of this cloth.
Eye brow tweezers were used to remove them. It was a joy seeing the metal jumping to the magnetized tweezers by the surrounding magnetic field as is described in the Burrougs book on the screwdriver example. The useful trick is one must not touch anything and you do not have to touch anything, it just jumps out.
Mic sound already a bit better.
Then the cloth was removed.
Horror of horrors there was so much magnetic dust around the air gap area.
Just a bit was tried to be removed.
Mic sounds already a bit better.
It is still very bright. And music ambience sounds bright but of very good HF quality.
If the capsule is removed from the back chamber, the sound is horror of horrors. Honky-tong.
More protective layers can be removed to reach close to the air gap. But may not be tried. The sound of the mic without any bass heaviness is interesting. Let's wait a bit a see.
Can low-fi be hi-fi
Sometimes.
It is not a paradox. It s just the context of the words.
When people say low-fi they just may mean the frequency response of a mic, loudspeaker, amp etc.
But when people say hi-fi they offer mean the whole signal path. Ie flat frequency response from producer's brain to listeners brain.
See also previous posts and the Lowe, Morgan Hollywood paper.
How about circular ring coil ribbon microphones?
They already exist and a great example is the Fostex series of printed ribbon mics. See Coutant for example.
But would they also be made unprinted? Ie not using an extremely thin plastic substrate membrane like condenser microphones.
Ie having a sheet of thin aluminum. Then a special cutting tool that would cut a spiral coil ribbon.
Friday, January 18, 2019
Interview of Bill Price from Studio Sound
Page 51
https://www.americanradiohistory.com/Archive-Studio-Sound/90s/Studio-Sound-1991-03.pdf
Cascaded inductor low cut filters inside the Beyer M600 microphone
http://www.coutant.org/beyerpdf/m600.pdf
The Pleiades cascaded filters inside XLR adapters is the same.
The Beyer has a series capacitor too possibly for not overloading the coil chokes.
Another sleeper mic, the Fostex M88 RP (printed) ribbon microphone
http://www.coutant.org/m88rp/index.html
It neither condenser, moving coil or ribbon but it could well be all three.
It has not been tried yet, looks very promising.
If understood well the idea is the following:
An extremely thin circular membrane such as one used in condenser mics is used. On it is printed a thin aluminium spiral ribbon coil.
There is a ring SN magnet above it and a ring SN magnetic below it.
The sound wave passes through each magnetic structure, so figure of eight.
The 2 magnetic structures above and below repel each other so the lines of force end up being perpendicular to the membrane plane. So the magnetic field is at any point on the coil perpendicular to the tangent at that point.
So each electron as membrane vibrates receives a Lorentz force in the direction of the tangent.
Electrons dance to the acoustic music waveform etc.
There is an AES 80s proceedings paper describing operation.
See:
https://www.gearslutz.com/board/so-much-gear-so-little-time/46839-fostex-m22rp-m20rp-printed-ribbon-mics.html
for the proceedings paper information.
And also there is mention at gearslutz of it being used on
Too Late for Goodbyes - Julian Lennon
https://m.youtube.com/watch?v=qVyswhYGrkQ
How would the Fostex M88RP sound connected to the Pleiades V6 electron tube battery powered booster mic amp?
God only Knows - the Beach Boys a Capella
http://www.coutant.org/petsound/gok.mp3
From in Coutant audio gear site
http://www.audiogearguide.com/articles/15
Are all these panels elastomer membrane low frequency absorbers converting acoustic mechanical low frequency energy to heat?
Some very interesting papers on ribbon microphones
Ribbon transformer, preamp damping from electrical loading etc:
http://www.aes.org/e-lib/collections/?ID=7
Thursday, January 17, 2019
First impression with beyerdynamic M88 N (C) serial number 42141
An amazing microphone. It has just arrived by DHL.
When I was a kid and even till very recently I didn't know this mic existed. Although it was seen at Live Aid with Phil Collins singing Agaist all Odds?
Big sound. Extended treble. No s problems. No p problems.
Smooth sound and frequency response. It has that kind of bigness, smoothness and naturalness of good omnidirectional moving coil microphones. It has not been directly compared yet to the other great directional mic, the AKG D25.
For close distance, ie less than 6in the Pleiades 130Ω,40mH gentle slope low cut filter was used.
Signal path:
male singing voice at 2 to 20in - beyerdynamic M88N(C) - Pleiades (130Ω,40mH) when needed - Sony TC-D5 Pro - Sennheiser HD580
It is now understood what is being said in so many forums; that this is what other mics should be if they were mics.
World class microphone
First impression with Revox 3500 s/n 016041 and 016091
They were tested after listening to the Sony F-96 omni.
They sounded unnatural with all that bass boost proximity effect and too much treble.
The Pleiades 130Ω,40mH filter was completely unsuitable (extremely bright result) as the mics are 600Ω. So the values have to multiplied by 3?.
Without anything else ie directly to Sony TC-D5 Pro, the sound is big and nice at 12in or more for male singing voice.
They must be tried with the piano.
Signal path:
Male singing voice - Revox M 3500 - Sony TC-D5 Pro - Sennheiser HD580
Recording a great vocal sound with a Sony MTL F-96 omni microphone
All that is needed is a (130Ω,40mH) Pleiades passive filter inside a Neutrik XLR barrel adapter just after the mic.
Example signal path:
male singing voice at 1-3 inch - Sony F-96 low Z - Pleiades (130ohms,40millihenries) filter - Sony TC-D5 Pro - Sennheiser HD580
The resistor R in series with inductor L, Pleiades filter can be used for reducing bass heaviness to listener's perception so that a big bright vocal can be recorded.
Attention to phase. The F-96 used was phase inverting so no phase change adaptor was needed as the TC-D5 Pro used is phase inverting too.
For comparing with a Sennheiser MD211 N microphone a phase reversal adaptor was included after the mic. The MD211 sounds much more bright and extended at HF.
But the F-96 sounds very respectable too and could be the right mic for a particular application. No handling noise too. No s problems. No p problems. Can send to the cleaners mics costing hundred times more.
One can experiment with various values of R,L on the Pleiades filter connected in parallel with voice coil. The filter due to the inclusion of R is a gentle slope low cur starting from a high frequency dictated by L and the mic's output impedance. Without the filter the sound is very bass heavy. Possibly due to Fletcher Munson and voice effort curves [Lowe, Morgan].
Later addition: Latter on today the Philips N8 207/00 (dark brown top) omni moving coil mic was tried. Amazing sound, does not need a Pleiades filter. Great extended treble and body to sound. It must have a very light aluminum membrane. Very loud too directly to Sony TC-D5 Pro. Sends for tea mics with 3 more zeros in the price.
Moving coil omnis have nothing to do with condenser omni capsules. In the former case the membrane is resistance controlled with a very broad damped reasonance centered at mid frequency range. In the latter case the membrane is stiffness controlled at some high reasonant frequency, shrill tinkie sound? Directional condenser capsules are resistance controlled at mid range just like pressure operated moving coils. So 2 directional condenser capsules set for omni sound good too. See also Microphones - Bore, Peus - Neumann.
Reference:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - Journal of the Society of Motion Picture Engineers
Microphones - Bore, Peus - Neumann
http://www.indigo-music.com.ua/info/downloads/neumann/docu0002.pdf
Wednesday, January 16, 2019
Keith Forsey
Interview from Modern Deummer by Erik Elderius
https://www.moderndrummer.com/article/september-2018-keith-forsey/
Monday, January 14, 2019
The Grundig GDM-19 microphone must had been made by Beyer
By browsing the patents at espacenet advanced search, with name Eugen Beyer, years 1950-1960 one of the patents that comes up has a mic that looks exactly like Grundig GDM-19.
Advantages of the Sennheiser MD211 N microphone
Very small.
Omnidirectional so leakage sounds great.
Free field equalized so on axis frequency response is flat. (Pressure doubling effect at HF is compensated).
Very smooth frequency response.
Very extended frequency response. (For intimate vocals a Pleiades (R,L) filter can be used for voice effort curves compensation so,that sound is not bass heavy).
No s problems, slight plosive problems.
Great, strong velvet lined case which is small and can nearly fit in a pocket.
Does not cost at all as much.
Small weight.
Looks fantastic.
Sennheiser MD211 n
Amazing sounding microphone.
For intimate vocals voice effort compensation is needed otherwise sound can be bass heavy to listener's perception. A Pleiades (130Ω,40mH) inside an XLR female to male barrel adaptor can be very useful. Of course values can be tweaked for particular application.
World class microphone.
Friday, January 11, 2019
Comparing a very expensive to a very cheap mic on YouTube
$20 microphone vs $12,500 Microphone - RoomieOfficial - YouTube
https://m.youtube.com/watch?v=2JjRZ-yct3U#fauxfullscreen
Thursday, January 10, 2019
Πως γινεται αυτη η βαθιά αντρική φωνη σε ηχογραφηση;
Υποθετικά...
Στο προηγουμενο post:
https://euroelectron.blogspot.com/2019/01/how-is-that-deep-male-vocal-created.html
How is that deep male vocal created?
This post is just speculation and could well be wrong.
Listening carefuly with the Sennheiser HD580 headphones on YouTube the excellent video on the vintage Beyer Dynamic M88 microphone...
https://m.youtube.com/watch?v=ar_YpOI9abU
And testing an AKG D25 with its low cut on...
It seems that the deep male voice (with no mid bass offending proximity effect) that one wanders how it is done could had been made using such microphones.
For example deep male sound such as on songs:
Sweet Harmony - Beloved
Barry White
Etc
The Neumann U47 sounds similarly as can be heard on the www.coutant.org sound example.
A Sennheiser MD21 can sound deep and big too.
Other omni microphones too. Such as Philips N8 207/00 dark brown top version?
How about Leonard Cohen?
Σκηνοθέτης του ήχου
Οπως ο κινηματογράφος εχει τον σκηνοθέτη που ειναι υπεύθυνος για το αισθητικό αποτέλεσμα της ταινιας...
Ετςι και η ηχογραφηση μουσικής εχει τον αντίστοιχο συντελεστή που ειναι υπεύθυνος για το αισθητικό αποτέλεσμα.
(Ο ηχολήπτης ειναι ιςως κοντα εννοιολογικά με τον διευθυντή φωτογραφίας η καμεραμάν κτλ).
Στο εξωτερικό αυτος που ειναι υπεύθυνος για το ηχο αιςθητικο αποτέλεσμα λέγεται record producer. Πχ για το Back to Black - Amy Winehouse ειναι ο Mark Ronson. Για το Imagine - Johh Lennon ο Phil Spector. Για το Χαμόγελο της Τζοκόντα - Χατζιδακις ο Quincy Jones. Για το Billy Jean - Michael Jackson ο Quicy Jones. Για το Careless Wisper - George Michael ο George Micahel.
Στην Ελλαδα πως λέγεται αυτη η ιδιότητα;
Wednesday, January 9, 2019
"Inharmonicity" of the human brain
For example:
440Hz together with 880Hz may sound horrible whereas,
440Hz together with 881.2Hz for example may sound great.
There must be a reason for it.
See also:
end of yesterday's post:
https://euroelectron.blogspot.com/2019/01/seeing-harmonics-of-vibrating-string.html
The Pleiades tuning for Korg Triton or Yhamha DX7 MKII
A Duet recording, Columbia EMI Athens studios
Σαν με Κοιτάς - Spanos, Alexopoulos, Fertis, Manou
https://m.youtube.com/watch?v=1BT2ydCiV0A
Recorded in either studio 1 or 2 by George Constantopoulos
Is the song You - Ten Sharp in B Dorian scale?
Possibly so.
Right hand plays firstly the B minor chord. Then E major instead of E minor ie G is sharp.
By the way on all the first 3 chords, the bass is pedal bass, ie constantly at B.
3rd chord is G major with B bass.
So overall the harmony code is;
(The notes F, G, C are sharp since scale is B Dorian)
B ie B D F
B(4,6) ie B E G
B6 ie B D G(natural)
Further reading:
Bach Bass Rules:
https://normanschmidt.net/scores/bachjs-general_bass_rules.pdf
Η αρχή απροσδιοριστίας του Χαιζενμπεργκ στη μουσική
Σ' αυτο το παραμυθι η Κανελινα η γάτα δεν καταλαβαίνει και βάζει τα κλάματα.
Πηγαίνει απαρηγόρητη στους σοφούς γλάρους στην παραλια πανω στον βράχο μεςα στο νερό να της εξηγήσουν:
https://euroelectron.blogspot.com/2019/01/a-piano-does-fourier-or-spectrum.html
Τι στο καλο ειναι οι αρμονικές χορδών;
Σ' αυτόματο παραμυθι η Κανελινα η γάτα κλαδί που δεν καταλαβαίνει και πηγαίνει στους σοφούς γλάρους στην παραλια πρωί πρωί να της εξηγήσουν.
Παραδείγματα στα αγγλικά στο διπλανό post:
https://euroelectron.blogspot.com/2019/01/seeing-harmonics-of-vibrating-string.html
A piano does Fourier or spectrum analysis, synthesis at the speed of light
It is easy.
A piano can also be an analog computer.
We hold with out foot the right pedal depressed. So all strings are free to vibrate in all their permissible modes of vibration.
Then we clap our hands and we hear the reverb of the clap from the piano.
Then we can close our ears. Let someone sing loudly a vowel note towards the piano. We uncover our ears and we can hear the piano repeating vowels, notes, even words.
A pulse having a short duration of time has a high bandwidth (Heisenberg uncertainty principle). We clap our hands. It lasts for a short time. All strings will vibrate sympathetically. All strings are pushed. The blast of air is short in time. If not the strings vibrating back would be decelerated. A short pulse therefore contains a large frequency spectrum making notes of all frequencies to vibrate.
Further reading:
Waves - Berkeley Physics Course - Frank S. Crawford Jr. - McGraw Hill
Seeing the harmonics of a vibrating string
It is easy.
We need an elastic rope or string of a few meters. (Sewing rubber band is fine).
Someone else holds one end steady.
We hold the other end at a light tension and we oscillate our hand sideways.
We find the first reasonance which is the fundamental mode.
We then oscillate our hand at roughly double the frequency in order to see the 2nd mode of vibration or 2nd harmonic or 2nd overtone.
At roughly 3 x (fundamentally frequency) we see the 3rd overtone etc.
Both partners in the experiment can feel the wave bouncing back and forth. As it finds impedance mismatching (our hand), it is reflected back and the back and forth reflections create the vibration of the string.
Tension is light. The speed of travel of the wave in rubber band at light tension is slow.
So we can see and feel everything.
If fundamental is A, 2nd overtone is roughly A octave above. 3rd overtone is E octave above A. 4th overtone is A double octave. Fifth overtone is C sharp above double octave...
When we play A on a piano all these permissible modes of vibration take part and we hear a rich tone. Each component of this complex waveform decays at a different rate.
Additional information:
The word roughly was used in this post. The wave may travel at a slightly different speed inside the string for different frequency. Why should the speed be the same? For example steel strings are elastic but also have stiffness. The second overtone of a piano string may consequently be a higher frequency than x2 fundamental.
At the same time the human brain wants a little more than x2 fundamental for a pleasing result.
If this "Inharmonicity" between string and human brain is matched for every note by the corect scaling of a piano we have a great piano. An evolution of hundreds of years leading to the great Steinway, Pleyel, Bechstein etc.
Further reading:
Musical Acoustics - Donald Hall
A Level Physics - Roger Muncaster - 3rd edition
Conceptual Physics - Hewitt
The Pleiades tuning - euroelectron
Tuesday, January 8, 2019
Εχω ενα μυστικό
Αλίκη singing to possibly an AKG D25:
Εχω ενα μυστικό - Χατζιδακις, Σακελάριος, Βουγιουκλακη
https://m.youtube.com/watch?v=ar_YpOI9abU
First experience with an AKG D25 microphone
Just preliminary test:
Hard to believe.
What a sound.
Possibly the first cardiod mic that has a proximity bass effect which sounds nice. The bass is deep but not offending.
So far it was only tested with the 12dB minus at 50Hz filter on. Is it an inductor in series with a resistor filter, Pleiades (R,L) filter?
The signal path used is as follows:
male singing voice at 3-20 in - AKG D25 with its deeper low cut on - Western Electric 1:2, (1H:4H) transformer - Sony TC-D5 Pro - Sennheiser HD580
What is also striking about this mic is the sound that makes you fall in love with it. Lack of coloration. Smooth frequency response. As if there are no abrupt microvariations. High frequency detail. No s problem. No s problem at all.
And the fact that it can be used more than a foot away in unfavorable acoustics and still get a world class sound quality.
Out of curiosity the Beyer M61 which was lying around in its box was tried. It is a mic that has a lot of proximity effect, a Pleiades (R,L) filter was connected. The sound is big but there are peaks in frequency response and coloration, hardness is apparent.
The AKG D25 sounds smooth as silk.
How is this done? Is it the impedance matching of the acoustic wave at the back creating an infinite tranmission line and no reflections or reasonant frequency spots of the membrane? See previous posts on the relevant AKG patent.
The sound also reminded the Beyer M88 example on YouTube:
https://m.youtube.com/watch?v=ar_YpOI9abU
Apparently D88 uses a similar acoustic impedance matching mechanism with its long tube at the back, see previous posts. An M88 has not been tried yet.
Also the very very much cheaper Beyer M55 omni was tried. It sounds very respectable. And also the Philips N8 207/10. The latter sounded bigger than M55 less clear but with a nice sense of harmonic distortion and a less somewhat plastic feel. Is it because it has an aluminum membrane?
But back to AKG D25. What a deep sound without offense. A ribbon mic kind of sound delivery at a larger distance. Singing at the back of it created an attenuated but still smooth sound. So nice detail.
Big output mic with its rocking balls.
Sunday, January 6, 2019
Abbey Road Studios mic collection shown by Lester Smith
The Abbey Road mic collection with Sylvia Massy - YouTube
https://m.youtube.com/watch?v=-QGYH7WN5X0
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Patent of AKG D12, D20?
US2848561
https://worldwide.espacenet.com/publicationDetails/mosaics?CC=US&NR=2848561A&KC=A&FT=D&ND=3&date=19580819&DB=EPODOC&locale=en_EP
Saturday, January 5, 2019
Similarity between AKG D12, D20, D25 and Beyer M88
It may be wrong.
Today while opening up a Beyer M88N(C) a plastic tube almost the length of the mic body was found inside a larger diameter tube touching the metal part of mic body.
The small tube feeds the larger one. So it seems it is an acoustic tranmission line of double the length of mic body.
By reading the AKG patent on D12 (see previous posts) could this tube arrangement be an impedance match of the back side of the capsule so that the acoustic wave sees an infinite length tube.
This is a relevant AKG patent:
https://worldwide.espacenet.com/publicationDetails/mosaics?CC=GB&NR=786111A&KC=A&FT=D&ND=3&date=19571113&DB=EPODOC&locale=en_EP
Inside the smaller? tube were found hundreds of twisted threads, acoustic resistance for damping?
When there is impedance matching the wave sees an infinite transmission line
Thinking for example of an open window where an acoustic wave keeps traveling trough space.
The game with the pendulums one striking the other. If there are for example 5 pendulums the last, 5th ball does not find impedance match and the wave comes back or is reflected. If the are infinite pendulums the wave never comes back or comes back in infinite time.
Does a book on History of Microphones exist?
For example showing the evolution of great microphone design.
The book could include sound examples for example Back to Black - Amy Winehouse using RCA 77DX ribbon mic.
Ribbon types.
Condenser types.
Crystal types.
Moving coil types.
Describing in simple words the great patents for example begin AKG D12, D25, Sennheiser MD441, MD421,...
Showing all the classic mics eg Neumann U47, AKG C12, Electro-Voice RE15 etc,..
Similarly for a book showing how to safely open classic microphones for servicing. It could be a book edited by someone and each particular mic section written by an expert for example on AKG D12, Sennheiser MD21 etc...
Friday, January 4, 2019
A setup is a vector space
For example:
(Song, singer, mic, mic distance, mic filter, mic booster amp,..., recorder, headphones)
Small dimension vectors may sound sound better as the signal path may include less components
Thinking of proximity compensation as a multidimensional vector space
For example:
When using a cardioid mic there is an optimum distance from mic to mouth for a natural non bass heavy brain of listener response. This distance may be 1-3ft. If a Pleiades gentle slope hush pass is used it may be 3in to 1ft.
Other parameter is the kind of song or voice register etc.
Other parameter may be the type of mic.
So we have a vector space of for example such elements:
(mic type, singing song register, Pleiades low cut filter cutoff and slope) <--> mouth to mic distance
The optimum distance may vary at different parts of a song.
Thinking of harmony or chords as a four dimensional vector space
For example the intro harmony of Hello - Lionel Richie
(A,B,C,E)
(G,B,C,E)
(F,A,C,E)
What's a vector space?
In mathematics it is a set of vectors. A 4 dimensional vector space has elements of the above kind ie (a,b,c,d)
Second experience with a Beyer M61 microphone
This mic came today protected inside its tiny box. It seems mics that come with their factory box sound better as they have been protected from iron particles.
This baby mic sounds fantastic and big.
Signal path, setup:
male singing voice - Beyer M61 - Pleiades (130Ω,40mH) gentle slope LC filter - Western Electric 1:2 transformer - Sony TC-D5 Pro - Sennheiser HD580
It sound reasonant in a nice way and broader band than a previous M61 tested. The low end is huge. It has to be more than 2ft away for flat response? With the Pleiades filter a few inch is fine and big.
How would it sound with a Pleiades V6 mic booster amp operated with just a 1.5V battery and the 2DV4 Nuvistor electron tube? Low cut filter should not be needed as at such low anode current there is already some bass heaviness cut.
What to watch out when opening a Beyer M88
At your risk.
Only do this if the mic is already in a terrible condition unless you know.
To be honest I do not know.
This is just some of my experience. The non working for parts mic that arrived looked as if it was used as a drum itself rather than a drum mic.
It is likely that while opening it up things may become even worse.
The XLR connector can be uncrewed after removing a very tiny screw near the end of the Beyer logo sticker. The tiny screw needs the exact size tiny screwdriver of great quality, otherwise the screw can be damaged. Watchmaker quality screwdrivers should be used. The wires inside the XLR compartment are very short and will be twisted many many times. It has to be done very carefully. But now thinking about it it is unlikely that the problem is there.
The mic capsule protective shell can be removed by removing 3 small screws. I washed mine with detergent and tooth brush as it was in a terrible state. Then used methylated spirit. It still needs more cleaning as the light does not pass through clearly from all points of the double mesh. The mic should be under a magnifying glass. Handling should be extremely delicate. Take your time. Breaking a tiny wire can cost much more time. Watch carefuly before trying to touch the capsule or turn it in order to start pulling it out. Handling may cause wires to break. It is important to find out where to place your fingers. More important where to not place your fingers. Or the so delicate wired may had already been broken.
There is a hum canceling coil wound around the capsule. This should be connected in series with the voice coil. If this is broken the mic won't work.
I do know yet how to proceed. Found 2 soldering terminal instead of 3. Beyer has been contacted for capsule replacement parts and service manual.
Fortunately a boxed Beyer M61 came by post today. It looks like a baby M88 and stronger and it sounds great and so big. Like a giant. (See next post).
For what was found inside (long acoustic tubes etc) see tomorrow's post:
https://euroelectron.blogspot.com/2019/01/similarity-between-akg-d12-d20-d25-and.html
Thursday, January 3, 2019
Did Donna Summer use a Sennheiser MD421?
It was read today on a www.hearthemusicplay.com article on best dynamic mics.
https://hearthemusicplay.com/best-dynamic-microphones-someone-know-going-mic-drop/
It makes sense.
A new Pleiades reference mic, Philips N8 207/00
Excellent sound.
Detail at HF. Great midrange. Bass without proximity bass heaviness.
Punchy and aggressive, due to the very light aluminium diagram?
Very loud and low noise.
500 ohms.
Omnidirectional.
Sounds correct without the need of any EQ.
Lightweight.
Attractive bright beige color.
(it seems the ones with the brawn top sound best).
Setup, signal path:
male singing voice - Philips N8 207/00 - Sony TC-D5 Pro - Sennheiser HD580
It sounds big and reminds the MD211.
How to make a random corugation ribbon
This is how 2 Grampian GR1/L or GR2/L ribbon microphones were re ribboned about 20 years ago. They sound very nice.
The corugations were made before the ribbon stripe was cut.
The few micron thin aluminium foil was held sandwiched between the 2 thin papers. It was then zig zag bent by hand in an accordion shape. Then it was placed flat again and then cut. So the corrugations were already there.
The ribbon was tensioned while listening to the mic (protect your ears) and tension was adjusted for max bass. The resonant frequency must be near sub audio.
Connections to the input transformer were done by same length cables in parallel like antennas, so that any field picked up would cancel. (Even the small length side wire was made long and placed straight along the side of the magnetic circuit structure. So there was geometrical symmetry between the 2 wires).
Wednesday, January 2, 2019
Another way to compensate for the proximity effect...
Is not having a proximity effect in the first place.
Or for example:
Trying a Philips EL1979 2 capsule stereo mic as follows:
Both capsules are connected in parallel. (The idea comes from AKG D45).
One of the mics removed from the base support. This is done by pulling it carefully.
Then mics placed side by side 180 degrees. So one mic is facing singer. The other mic is facing away from singer. Bass heaviness disappears and the resultant sounds like a good omni mic.
The diaphragm of these capsules is aluminum giving an interesting kind of aggressive sound. (The metal diaphragm can be seen if the plastic cover is removed and capsule carefully removed from disintegrating foam.
But why not using an omni in the first place?
This was tried after this test and the sound is great. The mic used is the Philips N8 207/00. Similar size capsule. Omni. Possibly metal diaphragm. Out of three examples of this mic one sounds really great. (Later addition, 2 sound great, phase polarity corrected. The 2 nice sounding mics have brown color top as opposed to black).
Signal path in above tests:
Male singing voice at 1-7 in - mic or mics combination - Sony TC-D5 Pro in mono mode - Sennheiser HD-580
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