Winding a Pleiades filter on Siemens Epcos core for using on AKG D112 for vocals

200 turns on the black ferrite Siemens Epcos core that just fits inside an XLR male to female barrel produced an inductance of 86mH. The insulated enameled wire diameter was 0.1mm and filled almost one complete layer.


This can be just about right for using in parallel with an AKG D112 for great vocals at 4in (bass proximity compensation) or in other words passive eqing. So the inductor is just connected to pins 2 and 3 inside the barrel and everything is nice and balanced.


On a Magnetec 073 core much less turns are needed for the same inductance.


The wire resistance should play a part too as it will shelve out the bass reduction at some low turnover frequency. (The coil reactance at 0Hz is 0ohms but we are left with the resistance of the wire).


Apparently a variable resistance is used in series with an inductor and the whole lot in parallel with the mic output on the Sennheiser MD421 to give variable bass cut slopes.

A way to connect the Sennheiser MD421 HN HL or MD21 HN HL balanced without modifying it

We just assume it is balanced and it may be.


The good news is that the center pin of the microphone is not connected to the metal part of the microphone.


So a cable can be made as follows:


A male Neutrik connector is connected  to a balanced twisted pair cable the normal way. X L R (external live return) ie 1 2 3.


On the other side of the cable:


The central mini Female Tuchel pin is connected to cable return. The live cable is connected normally to the low impedance Tuchel pin.


And the external screen of the cable is connected to the metal part of the mini Tuchel only.


The internal shunt autotrasformer? is a good thing as it electromagnetically damps extremely low frequencies, pop and wind.

iPad low cut filter on GarageBand audio recorder

A -3dB point was measured at around 250Hz. Lower frequencies than this seem to be greatly attenuated as seen on the Garagebands VU meter. Response at High frequencies was great 3dB at around 20KHz.


On the sampler of GarageBand the LC seems a bit more gentle.


Would the amazing engineers behind iPad and GarageBand add a switch to full bandwidth?


The inherent low cut can be useful for proximity compensation.


Fewer options force creativity, in the meantime one could record on sampler a high note of an instrument and play the low notes on the sampler keyboard. This works even on high pitch oscillators recorded by microphone or direct as on this setup. 10KHz tone recording gave great bass and mid notes as there was some kind of interesting distortion.


Setup:


Test tone CD - Sony D-EJ758CK CD player - Canford red Neutrik impedance converter 1/4in jack - Pleiades K117 - iPad mini

Could this have been recorded with MD21?

Rudi Carell can be seen on the MD21 instructions using the mic in his TV show.


A great singing video can be seen including Esther Ofarim:
https://m.youtube.com/watch?v=uGFeKdwJIb8


Have they sang using an MD21?

STC 4021 microphone

There is an amazing demonstration of 4021 by Martin Mitchell on YouTube.


https://m.youtube.com/watch?v=zXICfcS1fd0

Sennheiser MD21 vocals

It can be seen on YouTube, Steve Winwood Spencer Davies Group:


https://m.youtube.com/watch?v=TG32gmIIsVo


It is a great omnidirectional microphone so it exhibits no proximity bass boost effect.


The link was found on Martin Mitchells's microphone website.

How to convert an AKG D112 to a great vocal microphone without modifying it

An easy way is to connect to it a Pleiades filter.


This is an inductor in parallel with the signal out (ie voice coil).


An inductance of 47mH to 82mH should be great.


It can all be fitted inside an XLR male to female adaptor, more information on previous euroelectron posts.


The magnetic core used can be a Magnetec 073 or an Epcos Siemens ferrite etc.


These filters will also electromagnetically damp pops.


The AKG D112 is an interesting candidate as its frequency response has similarity with Neumann U47. The sound on voice is extremely natural.


More information on how to make these on older and newer euroelectron posts.

Close distance equalizer

Close distance microphone equalizer may be a more usable term for proximity effect compensating low cut filter.


A Pleiades filter is just an inductor in parallel with the microphone to do just this, attenuate the bass that is increased by using a directional microphone close.


When we use a directional microphone at very small distance even 500Hz is increased 400Hz even more 300Hz even more etc. So a Pleiades filter of 500Hz cutoff can be used to make the overall response flat from 100Hz to as high as the microphone can hear. We can still increase or reduce bass in voice by moving close or further from the optimum distance. (Examples of proximity effect for any distance can be seen on the AKG D310 frequency response curves.


The optimum distance depends on the microphone, the Pleiades filter cutoff, the singer, the end result wanted etc.


The Pleiades filter cutoff depends on the number of insulated wire turns wound on the magnetic core. Toroidal cores are very suitable as they as balanced even geometrically. They can do the trick with relatively few turns.


The process reminds photography were at close distance a macro lens is needed. Different Pleiades filter cutoff frequencies are used depending on the distance.


Pleiades filters can be combined together (one after the other). This is easy if each is made inside an XLR female to male adapter. So not many are needed as can be seen from earlier euroelectron posts.

Low cut by passing DC through microphone

At your own risk.


Current must be small. A high impedance source is to be used, one for example that has a high series output resistor.


This was by chance observed when a Philips N 8207 omnidirectional dynamic microphone was connected directly to iPad.


It sounded less bass heavy than usual and the reason might have been the resistor with voltage on one side inside iPad to power electret mic (amolifiers). The force on the diaphragm may change its reasonant frequency.


Variable current by a variable resistor may change low cutoff frequency.


It may not be recommended as this may produce contact sensitive noise.


Even barely twisting the headphones-mic plug may produce noise.

Ο στόχος στη ζωή Target in life

Ο στόχος στη ζωή ακολουθεί παντα εμάς.


We do not follow the target in our life but the target follows us.


References:
Interviews of Brian Eno on YouTube 

Nice sounding octaves and pitch dependence on intensity

We know a nice octave is a ratio in frequency slightly higher than 2:1.


Is this also affected by the fact that a higher intensity at higher frequencies gives lower pitch.


Experiments should be done very carefully at low intensity.


When good musicians play they take care of all of this automatically. They play by ear.


But how do they make sure that the listener hears the same? Same question for a conductor. Is the job easier for a producer to judge as he, she is sitting in front of speakers? What is the best reference level?




References:
Ernst Terhadlt paper on stretched octaves found on earlier euroelectron post

S.S. Stevens, H. Davies on pitch depending on intensity, Hearing - Stevens and Davis - John Wiley and Sons

Grampian GR1/L ribbon microphone to Pleiades to iPad to GarageBand

It took 1 day and 44 years.


A Pleiades step up transformer was made to increase the delicate ribbon microphone's signal which already has its internal transformer giving 25-50Ω output impedance. The Oleiades transformer is connected after this transformer, steps up the signal as normal input trasformer do and at the same time compensates for the bass proximity effect so that the mic can be used at 4in with natural frequency response from singer's vocal cords to listener's brain. [1]


The core used is the Magnetec Nanocrystalinne M073.


Primary winding is 14 turns of wire wrap orange wire giving and inductance of 4.7mH.


Secondary is 280 turns of 0.1mm enamel wire giving and inductance of 3.1H.


The transformer was placed inside an XLR female to male adapter.


It was then connected to the Pleiades K117 JFET impedance matching preamplifier inside a black female Neutrik XLR which is then connected by a video green cable and powered directly from the ipad's headphone mic socket.


The sound of singing voice was amazingly natural at 4in.


So was acoustic guitar.


Setup:


Living room - 4in - Grampian GR1/L - Pleiades 4.7mH:3.1H - Pleiades K117 - iPad - GarageBand - Sennheiser HD 580


[1] Sound Picture Recording and Reproducing Characteristics - D.P.Loye and K.F.Morgan - J.S.M.P.E.

Regenerative Echo on iPad by connecting a capacitor between headphone ground and mic hot pin

At your own risk.

Various values of capacitors were connected between headphone socket ground and mic hot pin on iPad mini air 2? The latency gives Echo and the capacitor gave regenerative echo (feedback, feeding back from headphone out to mic input). This gave a really interesting sound recording singing voice.

This came by accident while connecting a Heathkit box of capacitors to low cut high frequencies on the Pleiades K177 preamplifier inside the Tuchel connector for the MD421 HL mic. Various capacitor values were tried in order to compensate for voice effort and Fletcher Munson curves on the high frequency part of spectrum. 

The echo became apparent by chance by the clicking sound of the capacitor switch. Feedback can be adjusted by iPad's headphone volume until positive feedback takes over!

Amazing sound, analogous to the multiple selfs seen if you watch yourself between parallel mirrors. Electromagnetic waves bouncing which is really the same thing.

22nF for example gave nice results including reduction of any hiss from ambient noise.

The echo energy is low cut as ther is a capacitor involved in series. It is also high cut as the capacitor is between JFET drain and ground.

Setup:

Singing male voice Somewhere Over the Rainbow - 1 to 1.5in from mic - Sennheiser MD421 HN (LC low cut) - Pleiades K117 inside Tuchel connector - 3m video red cable - iPad (22nF between headphone ground and mic hot), GarageBand volume at 7, headphone volume at 7 - Sennheiser HD 580

Sennheiser MD421 HN and Pleiades K117 inside Tuchel connector and iPhone, schematic and photos

Possibly the closest there is to wire with power gain...



The complete setup from sound to recording



Caution: A gate resistor should possibly be included to avoid voltage build and possible damage to the mic transformer secondary when the microphone is connected.


         

The Pleiades K117 preamplifier inside Tuchel connector for MD421 HN and iPad, iPhone etc. No battery is needed as power comes directly from iPad's headphone mic socket which provides power for electret condenser microphone high to low impedance FET preamplifiers.





The cable with Pleiades K117 preamplifier inside Tuchel connector and schematic (pins shown are for XLR not Tuchel). The input transformer is not needed in this case as the Sennheiser MD421 HN HL already has one.

Connecting the Sennhesiser MD421 HN HL microphone to iPad GarageBand

The amazing MD421 HN very conveniently has a step ups transformer inside.


The high impedance is ideal to connect to a K117 JFET for extremely low noise.


The internal low cut is ideal for using the microphone at small distance, is this a Pleiadws filter?! (Inductor connected in parallel).


A Pleiades K117 preamplifier was built inside the Tuchel connector. It consists of just a K117 and a 220ω source resistor.  A schematic can be found on earlier or later posts. The drain of the K117 is connected to the signal cable to iPad. The iPad has internally the drain resistor and supplies power as well.


The sound was amazing as expected.


The iPad's GarageBand microphone recorder low cuts too, so the microphone needs to be used at 1in  which is convenient as ambience and noise is out. When the low cut is off the  mic needs to be used at about 9in?

An easy way to calculate Pleiades filters

Assuming 200Ω  mic impedance:


Examples:

100Hz is made of 320mH parallel to mic inductance
320Hz is made of 100mH
200Hz of 160mH
400Hz of 80mH
640mH of 50mH
160Hz. of 200mH


The product of cutoff frequency and inductance (Hz and mH) is constant.


The easy way to calculate any frequency or inductance is:


200 dividing by 2 dividing by 3.14... (π) devidibg by frequency or inductance to find one from the other.


Fco=200/(2πL)


L=200/(2πFco)


More properties of Pleiades filters such as the possibility to add cutof frequencies when 2 or more filters are connected one after the other (in electrical parallel) are shown in earlier posts.

Cutoff frequency for Pleiades low cut proximity compensating microphone filters

By using almost any directional microphone experimentally or looking at published frequency response curves for small distance, we can see (hear) the following:


The proximity effect affects frequencies that are right into the human vocal band when directional microphones are held at the usual distance of 9in to 1in from mouth.


So the Pleiades low cut filters must have a cutoff frequency anywhere between 200Hz to 677 depending on application. This corresponds to 160mH to 47mH. An input transformer with 47mH primary winding inductance is used on the Pleiades V5 electron tube battery preamplifier and compensates greatly for Electro-Voice RE16.

Electro-Voice RE15 to Pleiades with Neutrik modules to iPhone or iPad description and photos

Electro-Voice RE15 to Pleiades M073 step up transformer to Pleiades K117 preamplifier to iPhone, iPad or any device that accepts an electret condenser microphone



The Electro-Voice RE15 microphone is a variable D directional world class microphone. If we sing very close to it (one inch) like using all directional microphones we still get a great increase in mid bass and bass. Sensitivity may start increasing below 700Hz or even 1KHz in some directional microphones.


The mic is connected to a Pleiades input transformer. The primary inductance is deliberately low so that frequencies below say 700Hz are reduced in order to equalize the bass increase proximity effect. The Pleiades microphone transformer is inside the XLR adaptor made form Neutrik modules. This Pleiades microphone input transformer is wound on a state of the art Magnetec Nanocrystalinne tape wound core (metal glass) type M073. The primary winding is 30 turns, actually somewhat more is needed as the iPad Garageband has a low cut filter too. The secondary is 700 turns but actually less should be better as reasonance can be evident. Another XLR barrel adaptor containing a 100KΩ shunt (parallel) resistor can be connected at the output of the transformer to damp the reasonance.


The signal now is extremely clean and natural. Ambient low and mid low frequencies are extremely reduced becaude they do not excibit the proximity effect as they are far from the mic. We have maximum level from voice as we are extremely close and minimum level from anything less including bad acoustics.


Still this may be a small signal as the extra bass and mid bass have been reduced and we may like to be able to sing at speech level without putting effort to our voice. And we do not want any hiss (electron thermal noise or Johnson noise) to get in our way as it may be in a great recording studio.


The small and clean signal is passively amplified by the Pleiades step up transformer without adding any noise.


The Pleiades low noise JFET K117 preamplifier (inside black female XLR) matches the high output impedance of the Pleiades transformer to iPhone or iPad or any similar device. The circuit consists of just an K117 JFET and a 220Ω source resistor. As already mentioned a 100KΩ resistor may be needed to terminate the secondary of the mic transformer in order to damp an electric reasonance if it exists or is needed.


Devices like iPad have a resistor inside them which is connected to a positive voltage at the device side and becomes the drain resistor when the JFET preamplifier of an electret microphone capsule is connected.


So we use this to advantage to power the Pleiades K117 JFET preamplifier.


The signal by the time it enters the recording device is already clean, natural, devoid of any noise and high in level so the device is not given any chance to add its own noise.




Electro-Voice RE15 to Pleiades V5 electron tube preamplifier to Pleiades K117 JFET preamplifier to iPhone, iPad or any device that accepts an electret  condenser microphone



Similar reasoning applies to the Pleiades V5 electron tube pre amplifier.


The microphone signal is applied to the Pleiades transformer made from the Magnetec brown M 060 core shown inside the V5 preamplifier.


Only 35 turns of primary winding are used to give a primary inductance of 47mH (millyHenries).


47mH gives an excellent natural response with a mic such as RE16 at 0 to 1 inch when its low cut is on.


The secondary of the Pleiades step up transformer is 350 turns increasing the mic signal by 10 times and impedance by 100 times.


The EF183 electron tubes in triode connection can operate at extremely low noise and extremely low battery voltage because the grid is positively neutralised by a 4.7MOhm resistor from Anode to Grid. This happened from a comment by Hliana who said that the grid must be positively charged to make electrons free.


The amplified signal from the 1st EF183 tube is applied to the second EF183 tube so  and we can now drive it a bit harder and get that famous electron tube instant limiting sound with dynamics intact subjectively but compressed objectively as is done on all great recording studios.


The electron tubes are under-heated as is done on the Neumann U47 microphone for extremely low noise and maximum extraction of subtle information.


The very high, dynamically processed, extremely clean, hiss and noise free signal is attenuated at the output of the second EF183 electron tube to be brought back to mic level.


This signal is now fed to the Pleiades K177 JET pre amplifier to feed the iPhone, iPad or any other device. A 100KΩ resistor much be connected between V5 and K117 if it is not inserted inside the female XLR in order to make the JFET operate.


Pleiades circuit diagrams, schematics, and block diagrams shown on previous posts.

The sound is world class studio quality even if recorded in relatively noisy places with bad acoustics or
outdoors.

The small print on food ingredients/ Μπορούμε να διαβάζουμε στα προϊόντα διατροφής τα μικρά ψιλά γράμματα

Ειναι καλό να έχουμε μαζι μας γυαλιά η μεγενθυντικο φακό.


Οτι τρώμε μπαίνει μέσα μας. Μας αξίζει να γνωρίζουμε τι μπαίνει μέσα μας.


Λέγεται οτι τα επεξεργασμένα φυτικά λιπαρά φράζουν τις αρτηρίες. Προς το τέλος ακολουθεί μετάφραση.


Τα περισσότερα προϊόντα ευρείας κατανάλωσης φτιάχνονται με επεξεργασμένα και φθηνά φυτικά λιπαρά όπως φοινικελαιο, φοινικόλιπος, μαργαρίνη κτλ.


Τέτοια προϊόντα ειναι γκοφρετες, φθηνές βάφλες, φθηνό παγωτό, φθηνά κρουασάν, πάστα αλειμστος φουντουκιου,, φυστικοβουτυρο που στα συστατικά του έχει φοινικελαιο, φρυγανιές με φυτικά λιπαρά, χωνακια παγωτού, σοκολάτες και σοκολάτα ρόφημα εκτός απο 100% κακάο και σοκολάτα 100% κακάο που τότε λέγεται πάστα 100% κακάο.


Δεν έχει κανείς παρα να παρατηρήσει το πιάτο η κατσαρόλα φαγητού αφού κρυώσει οταν ειναι μαγειρεμένο με φυτικά λιπαρά αντί για ελαιόλαδο. Μοιάζει με πηγμενο κερί. Με αυτο φράζουν οι αρτηρίες; Έτσι πεθαίνουν τόσοι που μπορεί και να μην κάπνιζαν η έπιναν; Δεν είμαι διατροφολόγος και δεν γνωριζω.


Τα παιδιά δεν παθαίνουν εύκολα και έτσι ειναι βολικό τέτοια προϊόντα να απευθύνονται κυρίως σε παιδιά;


Μήπως ειναι καλό να προσέχουμε τι τρώμε μικροί για να είμαστε απόλυτα υγιείς μεγάλοι;


Το άρθρο αυτο μπορεί να ειναι όλο λάθος. Καλύτερα ελέγξτε μόνοι σας.


Ακολουθεί μετάφραση παραγράφου απο το βιβλίο Fringe Knowledge for Beginers -  Montalk


Food and Medical Industries


Τροφή και Ιατρική Βιομηχανία


Οι υγιείς έχουν περισσότερα χρήματα, χρόνο και ενέργεια για να κάνουν τη διαφορά στον κόσμο απο αυτούς που ειναι άρρωστοι, φτωχοί και με κατάθλιψη. Η βιομηχανία τροφίμων έχει χειραγωγηθεί απο το σύστημα ελέγχου για τη δημιουργία ανθυγιεινής διατροφής που μειώνει το ανοσοποιητικό και αυξάνει τον κίνδυνο καρκίνου. Η ιατρική βιομηχανία ....
Η συνήθης δίαιτα κάνει τους ανθρώπους ευάλωτους (ασθενείς) παχύσαρκους, χαζούς και αρρώστους. Το φθόριο στην οδοντοπαστα περισσότερο εμπλέκεται στη λειτουργία του εγκεφάλου παρα στην προστασία των δοντιών. Το λευκό αλεύρι στο ψωμί και τα γλυκά μειώνει το ανοσοποιητικό σύστημα, εοιταχυνει την παραγωγή των fat cells (κατα λέξη μετάφραση κυττάρων λίπους) και ειναι οδηγητικη αιτία διαβήτη. Η Μαργαρίνη (φυτικά, υδρογονωμένα έλαια) δεν μεταβολίζεται και καταλήγει στην κυκλοφορία του αίματος όπου βουλώνει τις αρτηρίες και οδηγεί σε έμφραγμα...
Μια ισορροπημένη δίαιτα με φυσική τροφή όπως ανεπεξέργαστα δημητριακά, σκούρο ρύζι, ελαφρά γεύματα, λάδι ελιάς και 100% βούτυρο (σ.τ.μ. βλέπετε συστατικά στη συσκευασία), φρέσκα φρούτα και λαχανικά ειναι απλούστερη και πιο φθηνή απο ψωμι (σ.τ.μ. εννοεί κοινό ψωμί;),  δημητριακά με χρωστικές, συντηρημένες τροφές και σκουπιδοτροφες (junk food). Η βιομηχανία σκουπιδοτροφης παράγει μέρους απο το κέρδος με το να ενσωματώνει βιομηχανικά απόβλητα σε προϊόντα διατροφής. Αυτός ειναι ο λόγος γιατί φαγητά για μικροκύματα, συσκευασμένα γλυκά και τσιπς έχουν στα συστατικά τους λέξεις που δεν μπορούμε ούτε να προφέρουμε. Άλλος ένας λόγος για να αντικαταστήσουμε αυτά με με φυσικά και υγειηνα.


Τέλος μετάφρασης.


Τι ειναι καλό. Πχ ελαιόλαδο, σησαμελαιο, ταχίνι.


Έχουν δεκαπλάσια τιμή ανα κιλό. Φυσικά η ζωή αξίζει.


Ισοκράτης: Η τροφή μας το φάρμακο μας.


Τρώμε τις μη επεξεργασμένες ωμες τροφές που τρώγονται.


Η τιμή ειναι καλός γνώμονας.


Πολλά απο τα καλύτερα υπάρχουν ήδη σε δέντρα γύρω μας.