Low Voltage Tubes

low mu or amplification factor for operation with low plate or anode voltage. Pleiades lab experience has found gm to be not as important for ultra low noise, low anode voltge, underheated heaters, batteriy powering (in series with protective fuse), Pleiades pull up bias or perhaps even better grid open or at space potential seem more important. So as a summary, low mu, low temperature to avoid secondary emmision, low glow to avoid photoemmision, low plate voltage to avoide secondary emmision by high velocity electron collision, open grid for no grid current seem to be important. Experience with moving coil or ribbon mics which seem much more demanding that MM cartridges due to fact that a mic signal has thousands times more dynamic range that a record playing cartridge signal (see the VU meter needle move not more than 20dB on LPs)... ECC82 are great at 6-12V anode potential with Pleiades bias. Even better for triode connected EF183. Nuvistors too. See older posts for more information. But all above electron tubes consume say 300mA at 6V which is a lot for a portable battery powered preamplifier. For just 10s of milliampers at say 1.4V... CV2269, record low consumption with just one AAA battery in series with fuse for both heaters and anode, see Pleiades v1, V6 etc, has not been tried yet at open grid with a bit higher anode potential. Also 1H4, see Pleiades V6 1H4 open grid, scary resolution and low noise. DCC90, DC90, DC96, DC70, DF97 etc which have not been tried yet at Pleiades lab seem great, promising candidates for pehaps the ultimate in quality and portability. Hearing aid tubes. For some references please see previous post.

Candidate electron tubes or electronic valves for RIAA MM or MC battery powered preamplifiers or microphone preamplifiers or astronomy radio telescopes?

They have to be low mu or amplification factor for operation with low plate or anode voltage. Pleiades lab experience has found gm to be not as important for ultra low noise, low anode voltge, underheated heaters, batteriy powering (in series with protective fuse), Pleiades pull up bias or perhaps even better grid open or at space potential seem more important. So as a summary, low mu, low temperature to avoid secondary emmision, low glow to avoid photoemmision, low plate voltage to avoide secondary emmision by high velocity electron collision, open grid for no grid current seem to be important. Experience with moving coil or ribbon mics which seem much more demanding that MM cartridges due to fact that a mic signal has thousands times more dynamic range that a record playing cartridge signal (see the VU meter needle move not more than 20dB on LPs)... ECC82 are great at 6-12V anode potential with Pleiades bias. Even better for triode connected EF183. Nuvistors too. See older posts for more information. But all above electron tubes consume say 300mA at 6V which is a lot for a portable battery powered preamplifier. For just 10s of milliampers at say 1.4V... CV2269, record low consumption with just one AAA battery in series with fuse for both heaters and anode, see Pleiades v1, V6 etc, has not been tried yet at open grid with a bit higher anode potential. Also 1H4, see Pleiades V6 1H4 open grid, scary resolution and low noise. DCC90, DC90, DC96, DC70, DF97 etc which have not been tried yet at Pleiades lab seem great, promising candidates for pehaps the ultimate in quality and portability. Some references: Open-grid Tubes in Low-Level Amplifiers - Robert J. Meyer - Electronics magagine, 28-volt Operration of Receiving Tubes - C. R. Hammond, E. Kohler and W. J. Lattin both found on the bookElectronics for Engineers - markus and Zeluff. Operating features of the Audion - E.H. Armstrong, the explanation of grid self bias etc.

Velvet Choir or Velvet Orchestra

Name given by Vicky. Ex mayor George has emphasied the importance of giving names, examples, a soft tender voice, eye communication.

Life's so good

220nF is connected from Stanton 680 cartridge to gate of 2SK170 on previous post on Walters Le Passific RIAA preamplifier

Life is Good

The fabulous Walter's Le Pasific RIAA Pre revisited

2nd stage added. It did not sound much impressive when connected to Realistic Disco mixer line in. But when feeding the Sennheiser HD580 headphones directly, jaw droped. Amazing smooth sound. Lucy on vinylengine listening at 3am to Pink Floyd raves about it. Congratulations Mr Hiraga and Mr Walters. Signal path: I've had the time of my life from Dirty Dancing LP - Technics SL1200MK2 - Stanton D6800 EEE-III - Stanton 680 moving iron cantilever cartridge - Le Passific MM RIAA by Walters, derived from Hiraga, one channel - Sennheiser HD580. 4 6V camera type batteries can be used in series inside a Bulgin 2AA battery holder? A fuse in series for protection. It is very low noise too. How would DCC90 triodes compare at such low anode voltage and perhaps open grid for perhaps even less noise or better sound quality? Heaters underhetated a bit or more too for even more detail extraction from magical vinyls. The high Gm model needs perhaps modification?, electron tubes can sound scaringly low noise even at 14 micramperes anode currect especially when open grid, see Pleiades V6 1H4. If more gm is needed then Pleiades bias from anode to grid could be used, but it may not sound less or equally low noise. How would such a fabulous 2SK170 stage sound as a microphone preamplifier? Would an open gate or less drain voltage make it even more low noise, or sounding better? Would an input or output transformer create easier a flat frequency response from producer's brain to listener' brain But back to MM or moving iron or moving coil. Can Le Passific Walters be modified for open gate?

How would radio waves from space sound like if converted to audio frequency?

Vicky sugested this while we were viewing vids on radio astronomy, how radio telescopes work etc. For example using a local oscillator and mixer to convert high frequency to low frequency.

Kimitirio Megalon Eterion

Giant Company cemetery

A great attenuating pad to feed transistor base?

Is possibly a series resistor. It can convert a mic in to line input. Example signal path: mic - Pleiades Siemens AC151 IV open base front end - 100K series pot - Realistic Disco mixer mic in - Sennheiser Hd 580

Electronic Devices with open signal control electrode

For example the Pleiades Siemens AC151 IV front end LNA (low noise amplifier) is so low noise when bias resistor is disconnected from base that it can descriminate between short circuit and 200 Ohms capacitively coupled to base. Ie it can read the thermal noise of a 200 Ohm resistance. Not so impresively as the Pleiades V6 1H4 open grid but it can do it even without an input transformer. It is very impressive how quiet both amps are at short circtuited input. And how loud they then sound when a dynamic mic is connected. Ambient acoustic noise is so much magnified.

A rough investigation on the Walter 2SK170 Le Passific RIAA preamp

Only the first stage was made up today on breadboard with 20 per cent at least variation in component values. Signal path:Dirty Dancing lp - Stanton 680 - 1st stage of Walter's le Passific - Realistic disco mixer at mic in (lower input load, a series resistor should had been used) - Sennheiser HD580. When Vb=9V, Vd is 200mV. When Vb is 18V, Vd is 2.5V. When Vb is 27V, Vd is 7 volts. It sounded clear, dynamic and nice but there was lack of depth (even in mono listening). For some reason best sound so far was with 9V with gate open and so charged that VD is 300mV. More investigation and second stage is needed.

How would an open control grid battery powered DCC90 (5A3) RIAA or mic preamplifier sound

Grid at space potential. It does not mean that grid potetial is 0. On the contrary it is negative because of thermal emission of electrons from cathode. But less negative due to electric field penetration from the positive anode. See older posts.

element (terminal) of electronic devices be left open (flowting)?

Pleiades lab experience has shown so far that it sounds better (more depth for example)and with low noise figure. On electron tubes, transistors (germanium so far), JFETs. Devices are left free to assume their bias, but we can steer the value by appropriate choise of Vb, load resistor etc. It reminds what can be read on the Wright Tube Preamp Cookbook that what moves must be free to move.

Our best times are now or those to come

All times are good anyway if we like what we are doing!

Sodium bicarbonate, sea water self cleaning teeth experiments failed?

At your risk, this is not a medical advice. After 2 or so years dentist Dimitris found some lack of adamantine. He suggested very careful mechanical cleaning of teeth after every meal with tap water if i do not want toothpaste, dental flosh as well.

Sound Volume and the Ear - Alec Nisbett

Intensity (sound wave power or energy/time) and volume (subjective loudness) As it happens the ratio of intensities in 3 dB is about 2:1. This is convenient to remember, because if we double up a sound source we double the intensity (at a given distance). So if we have one soprano bawling her head off and another joins her singing equaly loudly the sound level will go up 3dB (not all that much more than the minimum detectable by the human ear). But to raise the level by another 3dB two more sopranos are needed. Four are needed for the next 3dB -and so on. Before we get very we are having to add sopranos at the rate of 64 or 128 a time to get any appreciable change of volume. (euroelectron note, this should also explain why low power amps can sound much louder that we expect them to sound). Extract from the excellent book The Use of Microphones - Alec Nisbett. Vicky's gift.

Bias (quiescent point) of Pleiades Siemens open base transistor LNA (low noise amplifier) has changed by change in ambient temperature

As it is spring time and more photons come each day from the sun to the earth, the temperature at Pleiades lab is 24oC, collector current increased to more than 300 micramperes and more volatge drop (by ohm'sl aw) to the 33K load resistor caused a 0.5V collector voltage. The front end amplifier still worked but with distortion, (see also yesterday posts) and there were very severe sibilant problems while singing to Shure VP24 mic. So dentist Dimitris is not to blame. Load collector resistor has been changed to near 20kohms and amp is back to good low noise, interesting sound work again. Vc is again 1.6 volts.

Fastening signal transformer ring core with the large nut of 3 pin DIN connector

So for example the ring itself is around the connector or for example a Bulgin vandal resistant circular switch. But probably not a very good idea aestheticaly at least.

Plexiglass looks nice

A vandal resistant stainless steel switch is mounted on a small plexiglass sheet and looks nice. neutrik XLR, RCA mounted from the inner side should look great too as it is transparent. Should some Pleiades preamplifiers be made on a Plexiglass box?

Other failed Pleiades RIAA experiments

Connecting the Stanton 680 cartrudge to Pleiades Siemens open base AC155 amplifier to Realistic disco mixer line in: VU meter needle moves a little, there seems to be some distortion. Then connecting a passive RIAA network after the AC155 and going to mic in: Distortion at mid range. Sounds nice if 3.3Megohms is connected after the AC155 front end (this was found by chance by an interminent RCA dirty contact).

Is the best rule knowledge?

Is the worst rule ignorance? Are the worst rules knowledge being wrong?

1st Pleiades attempt of RIAA equalisation immediately after the cartridge

It works but takes noise considerations to limit. Signal path: I've had the time of my life from Dirty Dancing LP soundtrack - Technics SL1200 MK2 - Stanton 680 with low output D6800 EEE-III A&R stylus - 33K series 2K7 series 100nF series to gnd - 28nF from 33K to gnd and signal taken from 33K (inacurate network just used for a first impression) - directly to Realistic Disco Mixer mic in or to Pleiades Siemens AC151 open base pre or to Pleiades V6 1H4 open grid pre both feeding Realistic Disco Mixer at mic in - Sennheiser HD580 - listener's brain if any. When RIAA network directly connected to realistic mic in VU needle barely, barely moves but sound is nice smooth dynamic with nice deep bass and extended treble. When the AC151 is connected needle goes crazy, there is hiss at low passages, sound is nice but RIAA inacuracy may be taking place. When Pleiades V6 1H4 is connected more RIAA inacuracy is apparent possibly due to input and output transformers interplay with (V6 1H4 starved heater , plate voltage condition for low noise) input and output impedance in order to make flat frequency response to listener's brain when mic is used at soft voice, sound is more clear but less perhaps interesting with some hiss but less than the AC151. No input transformer should be tried too. Perhaps it might be better to do half of RIAA after the cartridge or all RIAA after the open base or open grid front end. Hiss would be inaudible but there may be overload of open grid base. 1H4 should be fine and after it a volume control should be a good idea to avoid peak overload of 2nd stage. Mic pres have to cope with a thousands times more dynamic range live signal anyway. The original Walter Le Pacific with 2SK170 should be tried.

Is it best to first knowing the rules of the game before any attemp to break them?

For example Bach Bass Rules pdf.

Should the RIAA equalisation be before any active stage?

An MM or MI (Moving iron cantilever such as Stanton 680)record player cartidge gives such high output that if it is connected to mic input of Realistic disco mixer, VU needle hits 0VU whereas a dynamic mic barely moves the needle. But it sounds like shaving a light bulb as there is no RIAA equalisation. Why feeding an electron tube or transistor something that would never want to listen to in our right mind? So why not putting the passive RIAA equalisation network right after the cartridge and then feed with a series capacitor an open grid tube extremely low noise amp such as the Pleiades V6 1H4? Would it work, for example using the Le Pacific MM RIAA passive filter or the pre itself with 1st stage removed? Would this avoid possible 1st stage overload by the razor blade signal usualy fed to the front end?

Should not there be a volume control after the first amplifying stage of a microphone or RIAA MM cartridge preamplifier is order to avoid clipping of the 2nd amplifying stage?!

Which is more low noise, open grid or open base?

After some preliminary listening test comparison between Pleiades V6 1H4 and Pleiades Siemens AC151 both are impresively low noise. When connecting the Shure VP64 microphone the transistor gives more gain and voice edge, it seems to overload easier when fed from Pleiades V6 1H4 as Vc is 1.5V. The electron tube is so smooth, quiet. How JFET would compare, open gate? Do radio telescopes use such low noise amplifiers as front end in order to detect few photons from the beginning of the univese?

Lee de Forest did it right in 1907 by connecting only a capacitor to the grid of his 1st triode electron tube amplifier on planet earth

Dr. Lee de Forest, father of electronics patented on 1908 the inclusion of a control grid inside an evacuated electron tube. Thus flow of electrons could be controled by an external tiny signal and the first electronic amplifier was made. After so many years we now have the internet. And the human race is inteligent not to waste earth's energy resources on sensual virtual reality. Ather all it is less energy consuming to caress a real human hand or foot. Lee de Forest on patent US879,532 clearly states that when the grid is flowting by isolating it with a coupling capacitor tiny rdio signals get even more loud on the earphone. This is confirmed on the Pleiades V6 1H4 front end microphone preamplifier. When grid is at space potential and a dynamic microphone is connected to the input transformer it sounds not very unlike the universe expanding. So low noise is the first amplifier on our planet. (a fuse should be connected in series with any battery for safety, a pad, series resistor, potential devider etc should be connected after the front end small signal amplifier to avoid overloading of subsequent amplifying stage(s). Further reading: patent US879532, Operating Features of the Audion - E. H. Armstrong, Open Grid Tubes in Low-level amplifiers - Robert J. Meyer - Oct., 1944 - Electronics Magazine

H Veloudina h gata tou dasous kamparetzou

Velvetine the forest's cat cabaret dancer

Have tests been run between Placebo and nothing? At your risk, this is not a medical advice.

Is it love or care that cures?

Can dilluted sodium bicarbonate in high quality water cure (aparent?) kidney disorder in a cat?

At your risk, this is not a medical advice. Tip of a sugar spoon sodium bicarbonate dilluted in (Theoni) mineral water has been sugested by Lambros for stone disapearance. After the pet hospital, Bebis (aged castrated California spangled cat) who has been given short life started drinking a bit more water again. He also visited Veloudina (young female California spangled) at the forest.

Last sentense of previous post should be...

... powered by one 1.5V battery through safety fuse. Everything in a small lightweight box. The preamplifier (small signal) amplifier is low noise. No sibilant problem.

Maximising gain of the one germanium open base transistor Pleiades Siemens AC151 VI common emitter RC coupled front end microphone pre pre amplifier

Maximum gain takes place at RL=33KOhm. Vb=-9V, Vc becomes -1.5V, Ic=250microamperes. It sounds very nice bringing out the edge of the voice. Signal path: reverberant room - male singing voice - Shure VP64 - Western Electric 1:2 input transformer - phase reversal (x(-1)) Neutrik XLR adaptor - Ci=56nF - Siemens AC151 VI open base - RL=33KOhms - Co=820nF - Realistic 32-1101A Disco Mixer at line in - Sennheiser HD580 - Singer's, listener's ear brain. It should be great fun to make a ring core ferrite Philips Ferroxcube output transfomer connected directly to Collector and power the transostor through this transformer with 1.5V.

Specifications of a Pleiades 2 open base transistor long tailed pair microphone booster preamplifier

It should be small like a cigarette packet so as to fit inside a pocket. There should be no edges or protruding switches etc so a Bulgin vandal resistant switch is used. It should be self contained with battery and lightweight. Power consumption should be rediculusly low. It should operte in class A but the trnsistors left open base to self bias themselves with low current for low noise?, high imput impedance? etc. It should therfore be very linear at very small mic signals and progresively non linear at higher parts of the signal waveform in order to hve edge nd bring out the detail of music, singer, sax etc. Everything inside should be neat and beautiful and the box may be made of transparent plexiglas etc. Input and output should be traansformer balanced and isolated. Beautiful ring cores should be used for such transformers. There should be no capacitor, no resistor. Miou. It may be called Pleiades open base BC109c long tailed pair. Schematic should be engraved on top of box and is public doamin. Connector may be female nut secured DIN 3 pole. Transistors may be pluged in on IC type base terminals. It should be fun to make at home, beach, forest etc.

If supply spool on Telefunken automatic magnetophon 72 runs erraticaly, possible cure in cleaning of breaking surface with methylated spirit water soluction while spool is running

From the Telefunken Tonbandgerate Magnetophon 75-15, 76 Werkstattanleitung Ersatzteilverzeichnis service manual.

Interesting youtube video on the adventures of a one transistor microphone preamplifier

Christos from Paulatos distributors kindly gave a Philips Soft Ferrites 1998 Data handbook mA01 and white low profile ring ferroxcube cores

A 2 open base transistors long tailed pair microphone booster preamplifier with no capacitors , no resistors, only 2 transformers

Mic is connected at primary winding of input transformer. Secondary winding is connected to each transistor base. Emminters to minus supply ground. Collectors to to output transformer primary. Center tap to Vb+ through a fuse for protection. Secondary is lower Z balanced output. It is thought to be tried with 2 BC109C or BC549 and 1:3 input transformer and 3:1 output transformer. Will it work? How would it sound like?

(RL) load resistor on previous post should had been written 5K6 or not 56K

What is the optimum value anyway?

Listening to the Pleiades Siemens AC151 one transistor open base front end microphone amplifier at overload level

Signal path: Shure VP64 with male singing voice or Alan parsons Sound Check 2 CD played on Sony Walkman cD Player with its line out attenuated by a 600ohm to 600ohm variable dB laboratory Solartron attenuator - Pleiades Siemens AC151 with Cb 56n when mic is used or 220nF when cD is used for -3bD at 100Hz and flat beyond 20KHz with no negative feedback, base open, Vb=9V, RL=56K, Cout+820nF - Realistic disco mixer at mic in or line in when mic was used or line in when CD was used - Sennheiser HD580 fed by disco mixer or directly by AC151 through a Canford red output transformer inside a Neutrik 1/4in jack. The AC151 prepreamplifier passes the low noise test by canselling effectively the ambient noise when mic is connected out of phase (caution to ear protection needed, see previous post). Mic sounds very clear, the WE 1:2 input transformer was also used with excellent results. The unprocessed sounds on the Alan Parsons CD, near or after overload: Sinewave nice gradual overtones at gradual overload. Voices very nice, soprano reverb out of control intermodulating. Piano nice. Acoustic guitars excellent like Torn - Natalie Imbruglia. Electric, bass guitars very nice distortion. Flute great distortion. Saxophone amazing distortion at any overload level, shows how these amps bring out the edge inside music. Percusion great like those amazing Enoch Light LPs. Cymbals sound bad at overload.Hi hat sounds amazing at overload, again detail inside music brought out. The first orchestral track sounds bad but the later one sounds very good at overload. The techno track sounds amazing. Pipe organ nice too. It seems definetly worth building this preamp inside a plastic box with 9V battery cover. Just a transistor, 2 coupling capacitors and a 56K load resistor. Current consumption at microamp level. Battery may last for ages. Solar powered too?

The more transistors are treated like electron tubes the more they behave like them

For example when comparing an open base low level amplifier transistor stage to an open grid one. The transistor becomes very low noise with a high input impedance. Even biasing with 1Mohm from Vb to base increases gain but noise becomes unacceptable high see Pleiades Siemens AC151 one transistor microphone booster front end. At open base distortion is gradual too as well as overload behaviour like an electron tube. Do transistors behave like JFETS when base is left open, unbiased?

So many decades had been wsted by looking at scopes or spectrum analysers rather than using the best instrument available in the universe which possibly is the ear brain

Forunately it is the music lovers listening and the recorders listening too that have saved electronics

I have never understood what bias to electronic amplifying devices is

At university I was told it is a voltage

Why not letting the first amplifying stage after the microphoneto be the most linear at low levels and gradualy non linear at higher level?

After all is this not what we do when we listen to Frank Sinatra on YouTube? Or what nature does with human or cat ears-brain in order to extract as much information?