This is a great sounding 300B triode amplifier that I am sure DIYers will find to be very rewarding. I will briefly explain the cross coupled circuit here as for the rest of the 92-B amplifier, please, read the 86-B vignette. Paul Voight, England also made a feedback amplifier before Black, UK Patent 231 972 , but Voight provides no broad information about the properties gained, neither were any equations suggested about the virtues of the feedback scheme. Here above is some more pictures from the hand of Kris Walter of “radio-antiks”, showing the Victor R-34 radio with the type 245 amplifier. AL4, CL4, EL3, PT625 just to mention a few. 7-A  was intended to amplify headphone type early radios as well. It may not appear so, when visually inspecting sine waves at the oscilloscope and it may to a certain degree be hidden inside a negative overall feedback loop, but never the less this is exactly what this circuit does to the performance. Mesh plates increases the surface thereby increasing the maximum allowable plate dissipation as well. You may then connect any point between these resistors to ground and consider this point as our 0 Volt reference point. Now, as I also wanted to see with my own eyes, if the W.E. Let’s for a moment ignore the output transformer T2 and the capacitor C2 and deal only with the network of C1, R1, R2 and the secondary winding of the input transformer. AD1 The circuit above was a typical SE amp of this period. The filament of this direct heated triode are connected directly to ground via the center tap ( midpoint ) of the heater winding. When you intent to get the maximum out of a 300B, and operate this tube at the limits of safe operation, it is a better idea to use the 300B-XLS in such a case. The DC current path is shown in blue. Current (new) production 300B tubes like the Electro-Harmonix 300B and the JJ 300B sound wonderful at a fraction of the Western Electric 300B price. Both of these circuits can be made with the cathode resistor decoupled or not decoupled. Free shipping . 5 – 6000 Ω will do nicely. Several modification notes were published by W.E. This one has -3dB at about 20kHz. The cathode is returned directly to ground and biased in the same manner as the first stage. I fail to see the advantage of this network, but I will investigate this circuit throughout soon and update here. The DC idle current passes through two resistors, in this case 1k Ohm and 100 Ohm. The KTZ63’s may be swapped to same or EL84, even a pair of triodes with a medium u will do the job. Langmuir studied in Europe and went to General Electric in 1909. The 5U4G is a common rectifier, but 5Y4GT, EZ81, 5R4G etc. All others before this was merely detectors, that at best amplified a positive or negative part of the wave or rectified it into a modulated phase signal as they were gas filled, soft vacuum devices and negative grid bias was not applied. It is as simple as that. Early audio enthusiast kept sticking to acoustic recordings way up in the 1950’s. Many find them difficult to understand. ( Operating in the non linear area )  Much better is triodes such as the ones suggested. Hats off to Jefferson, Gentlemen….. 300B heater is AC direct. Continuing the 80th anniversary celebration of the 300B, Western Electric is unveiling a new single-ended amplifier called the 91E, as an homage to its famous predecessor the 91A, first introduced in 1936. Another amplifier from WE, that glamours in plain simplicity. US $385.17. More to come about this fascinating amplifier. Clone Audio Note Kit1 300B single-ended tube amplifier power amplifier, without large loop feedback HI-FI design . Sep 10 : I am for the time being working on an extensive laboratory test of the W.E. The inter-stage trannie should be close to 1:1, as well. 14) Increased consumer market due to high employment. I have redrawn the circuit  – once again, now only with the necessary components. The audio quality of TV-transmissions was said to outperform the conventional AM radio.The highest quality of audio had to be experienced in the cinemas. ( The books – that is ) And the price would have been something like a monthly regular salary. It ought to be a piece of cake, with modern technology and materials and I would guess that these are at least as good as the original. It was a 212-D PP driven by a pair of 211-E’s. Well, strictly speaking, this is not a trick performed only by W.E. I will show how this affects the quality. I am sure it was a lot better than the common carbon microphone )  A.E.G = Allgemeine Elektrizitäts-Gesellschaft which in English means: General Electric Company. Solder a wire from B+1 and ground to the resistor or use GOOD high quality high Voltage clips. What really tends to hold the tube characteristics as constant as possible in a space charge vacuum tube is the temperature of the filament. Below you have the cosy night vision…. Other good reason for using the power tubes as rectifiers as well, was in the maintenance and service. At the illustration in Fig.2 above the two 1,5 Volt batteries are connected to ground at the plus pole. ), The Western Electric 216A triode. amplifier from 1932. AEG was founded by Emil Rathenau in 1883. New production KT66, 6L6G, EL34 or EL37 is indeed available. Add Reverb to the western electric circuit. The early amplifiers from the beginning of the 1920’s were just as often used for speech amplification , meaning telephone as for radio. お問い合わせ 資料請求. Western Electric developed the 211-A in 1923. Today we can swap the 6u paper capacitors to something a little larger. Note the grounded cathodes, the Voltage divider ( 45R and 670R ) in the current loop of the PSU and the clever use of the lamp as ballast. ( 4,7Ω x 1A = 4,7V  +/- the precision of the resistor ). The 102D’s are supposed to draw 1 Ampere through the series coupled heaters. Western Electric 42A, 205D PP and 205D rectifiers. The wireless telegraph in the form of  “Hertzian waves” ( radio waves ) had been introduced by Marconi , Braun and Tesla shortly before WW 1. Armstrongs contributions is often overlooked due to his ever lasting disputes with Deforest. I have got this mail from Andreas Schubert : “Reading your page the Klangfilm 31620 diagram is simply in error.This happened frequently with Siemens diagrams and was even more likely in the “simple” old drawings of pre-war cinema equipment.It does not work, the grid must be connected to the other side of the choke, the bottom choke side grounded, where to connect the 250pF cap must be found out by comparison with an actual amplifier. This is an unaltered copy of the original 1993 article, re-published for the information it … Here we go: The Amplifier Compendium: “100 Amplifiers to lift your hat”, _________________________________________________________________. 32-A, does not provide any load to the input transformer. This amounts to a total gain of 92dB’s. Many industrial, military or otherwise professional tubes were also produced. Anyway – damn interesting design, thank you for drawing our attention to that odd amplifier, Joe. Brand New. As always with significant inventions and discoveries, it may be questioned whom was the sole person behind. The First Series "030" (FS-030) is specifcally designed for use in sophisticated low-to-medium power single-ended circuits. ( Keep the resistor load connected during this test ) And be ready with the on/off switch. It is mono block amplifier x 2, western Electric 91A type, prestage is 310A drive 300B tube. I would probably change it to autobias, reduce the gain and at the same time get rid of the input cap. That is – if you can get your hands on some 205D’s. WAD 300B amplifier: page 2: Part 2: page 4: All Pages: Page 1 of 4. The second stage is a nice interstage triode phase splitter – again  however – with that degrading resistor in series. I am impressed and I really like the odd look of this amplifier. Two chokes to smooth – I like that too. Jefferson, 2A3 PP. DA41’s are available at reasonable prices. The “secret” behind these power driven amplifiers are the transformers. Drinks. This calls for an AC coupled input, hence the 5nF input capacitor. ( Wrongly claimed to be 100.000:1 – in the IEEE article ) The Swede Nyquist, also at Bell Labs, worked out the maths behind the negative feedback scheme. Certainly the first commercially available audio amplifiers were mechanical acoustic horns. 211 Pictures courtesy of Kris Walter, www.radio-antiks.com ( Lots of beautiful pictures. and October 1993 DIY Supplement No5. The u was a rather modest 6 ! Harold Black and Harry Nyquist, Bell Labs. The “secret” is the two resistors I have marked R1 and R2 in the redrawn schematic. Using audio output transformers with a primary impedance of about 3000 to 3500 ohms you can expect about 8W of output with at about 2.5% THD. Top Rated Seller Top Rated Seller. grid to cathode trick, that is discussed in the Vignettes regarding W.E. This means that even the very small current drawn through the large 500k Ohms grid bias resistors may saturate the core of the gridchoke. The purpose of the feedback scheme in the 92-B, may have been to improve the freq response as positive feedback at high freq will lift the upper roll off pole. This is so wonderful that you feel that nothing can equal it at similar prices certainly. Yet another forgotten, but delicious W.E. From China +C $22.83 shipping. 300B STC solved this by means of a 6L6G beam power tube and lots of Voltage at the plate. ( See Fig. Nice ! Explore. will do just as good. trick later on. Apparently WE suggested that it should be driven by WE 9-A, which is a 205D Push Pull, capable of some 4-5 Watt’s. From the collection of Ernie Hite, Photo. Progressive tax systems kept this circle going. In this case it is relatively easy for a single 310A to serve as the Voltage amplifying stage as well as the driver for a 300A, the 300A being auto biased with a grid resistor of 500k Ohm. But as the grids enter the positive area, the 807’s will gradually open for current to pass between the cathode and plate. Down below is what I suspect to be a mislabeled or “false” Western Electric circuit. You may keep the input trannie, in which case a 1:1 or similar low ratio type will do fine. I'm skeptical about rebirth of Western Electric tubes. The … It wont draw much current even though these grids are at ground, the same potential as the cathode. Seen from the power supply, there is no AC current drawn, only a steady DC current, provided that we drive the amp in class A. 6L6G’s is to this day the most commonly used power tube in electric guitar amplifiers. ( A peculiar side note – the same year as these two 1924  amplifiers was introduced, Siemens invented the ribbon band microphone. Now, this DA250 amplifiers is an extremist  amongst the extreme. A field coil speaker may be employed, should you happen to have such laying around. Neither will they sound too good in such set up. IMHO, the las choice you can make 43A is the same circuit as 42A….Only big as a desk….and 211’s instead of 205D’s. Note the parafeed driver and the 1:4 step up ratio at the tapped autotransformer. Charlotte ARC, Western Electric 46 A/B/C/D/E/A-46-A , 205-D PP, 1927 to 1933. Finally is it known that Philips in Nederland was investigating feedback, but no proof of their findings are brought to the public – as far as I am aware. First of all we need a lot of high Voltage and that is not really what I long for, secondly and more importantly the danger of errors. Awesome. Hi-fi. In this schematic also there are no passive components on the signal! 91-B drawn with the PSU and amplifier separated from one another. The Russian GM70 is not an equivalent, although a similar – but less linear triode. It is not necessary to use Western Electric 300B vacuum tubes. Later 10-A models used 242’s triodes – 242’s is very close equivalents to 211’s. The power tranformer is a Hammond 278X (800V CT @ 230mA + 5V CT @ 3A + 6.3V CT @ 6A). Well, to be perfectly correct, the capacitor also provides a lower inner impedance of the tube, hence a higher roll-off. In case that you would want to play with the adjustable bias network I have suggested in Fig.3, be aware that adjustment affects all valves in the bias loop. I have received some mails regarding the W.E. Although this “pro-use” Klangfilm amplifier is not as straightforward as it may seem at glance, it is a good example of such application. The important thing is that we end up with Voltages close to the suggested 500 V, when the amplifier is on. Buy It Now. It deserves a deeper analyse and I will probably get back to this fascinating design later. If you have a personal radio home page, club web site, or commercial site you'd like shown here, send an e-mail to Friendly Webmaster and I'll post it here. The input resistors was used to attenuate – if wanted and the resistors at the output is used for the meter and to maintain loading and to ground the secondary winding. I would place an input volume pot before the 310A and it is worth trying to triode couple it. Later data sheets say 40 Watt. Western Electric also designed and engineered audio amplifiers, CD players, phono pre-amplifiers along with other audio components. 1 in this vignette ). ( Suggested by Joe Roberts ) If we ground at point A we only have positive Voltages available. Another beauty from the hands of the Bell Lab. did it this way, was due to the poor technology of capacitors back then. Click to get the latest Buzzing content. ( Pardon my French ), Shortly after this amplifier was released, WE changed the orientation of the small pin at the side of the socket at the 300A, in order to make it fit the old 205D sockets. It is plain and simply rubbish. ( 1929 ), Western Electric 100A & 100B amplifier. Fig. It can be matched with all genre of music even Jazz or classical. Most of the special WE tricks were practical and economic solutions made to practical problems and clever practical solutions to improve stability and to insure safe long term use. Same thing with Sun Audio SV-300B. It just does its job, period. 1-A. This means that we have a minus 3V supply. The OPT for the bass is connected the conventional way, but the transformer for the high end of the freq range are AC connected via a single capacitor. The 87’s amps was supposed to be driven by a WE 1086 Amplifier ( 86-B , 300-A PP ) . [/size] [size=16.0pt]I have created a Dropbox folder to put all the schematics, BOMs, Photos, and Specs. 3: The usual choke input power supply that seems to be mandatory for W.E. or Best Offer. Apart from the mentioned, this amplifier is quite similar to the earlier Western Electric single End amplifiers. The two interstage transformers could be about 1:1 or 1:3. In the meantime it is here for you to admire. 3) Spectrum analyzer: Hewlett Packard 8535B , 20Hz – 40MHz This AC signal is in parallel with the tube, the plate resistor ( not shown ) and the grid circuit of the following stage – indicated by the red line. The power output of the Woodham is about 8 watts of … This is an advanced circuit, despite the few components. This precious design uses the W.E. There was a lot of fine made English amplifiers during the 1930’s. It is frankly a mess, too many crossing lines and so forth and so back. It makes good sense to do ones best to reduce any possible capacitance in a class B circuit as these loads the driver hard, in particularly at high frequencies. This was indeed times of which the logo and name tags meant a great deal. 205′ amps in my archive. There is no doubt the Western Electric 300B offers amazing sound quality, but other brands of tube are very close behind, each offering a subtly different presentation. ( 205E and 4205E ). お問い合わせ内容. 2) Version with soft start option. Take A Sneak Peak At The Movies Coming Out This Week (8/12) “Look for the helpers” – Celebrities helping out amid Texas storm I cant help but smile and rejoice this elegant and simple design. The 9-A was made for “Sound Projector Systems” = cinema. Hallelujah….. Radiodyne by Atwater Kent 4340 Model 10, 1923 from the collection of Ernie Hite, Photo: Charlotte ARC. For best performance you will want to used the best audio output transformers you can get your hands on. This 20mH coil and the common 4uF at the cathodes of the 271’s are meant to cancel differences, meaning distortion at the output. Excellent mechanical lay out. On the other hand is this same current very low for a heater and may easily be supplied from a low noise phantom alike PSU. Even better, dump one of the 262’s as well…The 252’s draws some 40mA, meaning that a peak of 40 Volt will provide full output. This one obviously had a “gramophone” as well. Western Electric performed the same little trick in the W.E. ( Plate Voltage: 2500 Volts, cathode current: 100mA, load: 17-18kΩ ! ) The 126A tube was apparently made exclusively for the 7-A  amplifier. Now, if we want to apply a load of 34mA between the 500V point and ground, we will need a resistor of 500V/34mA = 1470Ω. We appreciate the achievements of old-fashioned single- ended 300B amplifiers, but the dream of the full potential of 300B for musical reproduction has only come true with the creation of the EC-300B amplifier. Just as many audiophiles today stick to vinyl and/or tubes, so did serious audiophiles stick to acoustic reproduction all the way up to the 1950’s. This is Altec A7 and 300B Single Ended Amplifier Western Electric Site Hashimoto was division of Transformer for ex Sansui Audio Company Hashimotowas ex SansuiUSA Cetron 300B using Single Ended Amplifier on 2016 June Note: Cetron 300B is made by Rechardson Electronics around 1995 Made in USA .100 % copy or same of WE300B BC-614 was a combined transmitter and PA-amplifier/modulator. But the principle – or method if you like, is absolutely the same. Note the large field coil speaker and the decorative tuning adjustment. This means that the bias is made by the current through the resistors R3 and R4. In Fig. This is the first true full wave vacuum tube power amplifier – that I have been able to find. These are the only components involved in the relation between the grid and the cathode. But even there the journey will not end, the concept can be enhanced to an all DHT amplifier with directly heated triodes in the driver stage as well. The famous triode was developed at Bell Labs in 1933 in the form of its predecessor, the 300A, which was modified, patented, and then produced at many historic works facilities … ). First the input transformer, then the two 310’s and finally a little gain from the 300A.