A push pull valve amplifier almost invariably follows one of the two schemes shown in block diagrams below. But as my goal is to allow you to think like a circuit designer, not to force. Next pushpull end power amplifier published by sakuma next amplifier in chronological order. After having built several audio amplifiers singleended and pushpull and compared, first their theoretical quali. There is a nice dc amplifier circuit here which could make a good basis for driving a pair of these tubes once its 40hz hf cutoffs are removed. When the screen grids are connected to the high voltage supply you have a standard pushpull pentode amplifier circuit 1. I didnt bring my 6146b push pull amp as it was only for use with 220v and big and bulky. I would like to make a push pull amplifier using 2 6c33bc triodes per channel. I actually have four of the tubes for a class a pushpull pair.
There are many pentode good for audio amplifiers but the most common in the current production are the el34, 6550 and the kt88 so follows a compare table with the main characteristics and price. The pushpull cathode follower output impedance is four times the theoretical minimum because the two cathode followers are in series, not in parallel. Two of these are often used in a push pull audio amp. The end result is a solid performer with decent power, sounding unlike pushpull pentode designs. Output, high voltage power, low voltage power, input and coupling. Id be concerned with dc saturation with a toriod opt and 6c33c, especially. This page is about unusual pp amps with series output tubes in triode class a, and for use of ul pp opts to obtain local cathode feedback for much greater linearity in the output stage. Classa pushpull tube power amplifier electronics diy.
Also history is an interesting topic as it was developed for use as a. O ne of the most particular looking electron tubes on the market, the 6c33c. Great, draw the loadline as seen by one output tube in a classab transformercoupled, pushpull power amplifier. Pushpull class b amplifiers made with bjts can be constructed using a npn transistor for one element and a pnp transistor for. A view of the 50wse6c33cb amp with the left and right. Whats so irresistible about a singleended triode set amp. This is hi quality bass guitar amplifier with output tv sweep tubes pl500 pl504 27gb5 el500 el504 6gw6 6p36s 6p41s 6gb5 push pull class ab2. A kennedy audio labs, and is provided with the understanding that this information is for personal use only. Hi quality push pull amplifier with pl500 pl504 el500. I often, all too often, get email that asks if the circuit that i had shown and. The result is the fatboy 300b amp named as such because, like me, it is a tad overweight.
The ultra linear arrangement applied to both a singleended and a pushpull stage. The class of operation has nothing to do with whether the amplifier is griddriven or cathodedriven. Version 1 uses two 6sn7s in the input stage, and delivers full output with around 300mv input. It is a pushpull amplifier using 2 845 output tubes. The long and the short of it is that the two primary windings of jacmusics schematics leaves the two in opposite phase. A pushpull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. The information provided is and remains the sole property of kennedy tube audio a. Susan parkers zeus zero feedback pushpull transformer audio amplifiers. Super triode connection drive 6c33cb single ended push pull otl. Amplifier design the design of a high power pushpull amplifier operating from 150 volts requires several decisions. Adjusting bias on one of 6c33 tubes had a profound impact on speaker level, although still seriously distorted. Hier mein projekt, es handelt sich um einen 6c33c gegentaktverstarker.
The other tubes are per channel two 12au7 and two el34. One thing about diy audio is that it is a journey, not a destination, it never ends. And, the output stage is a cathode grounded amplifier. Singleended pushpull otlin the sepp output stage the load appears in the cathode circuit of the upper tube and in. Department of electrical engineering national institute of technology, rourkela odisha, india769008 certificate this is to certify that the thesis entitled design of high performance class b push pull amplifier, submitted by abhishek anand roll. This has to be one of the reasons for using it in many amplifier designs. This classa pushpull tube power amplifier uses a pair of pushpull class a, ultra linear mono block tube amplifiers that can be used with several different vacuum tubes including kt77 6l6gc kt88 with a 12sl7 driver and 6no30 tubes.
I3xi03 single tube dual triode pushpull circuit tube audio amplifier design application of class b power amplifier with high load resistance power amplifier transformer s17 power transformer class b driver transformer amplifier. To create a push pull amplifier is possible to use triode and pentode but obviously to test many configurations like the ultra linear we need a pentode. In contrast, a pushpull amplifier, which uses a pair or more of tubes, splits the plusminus of the music signal, then it has to put them back together to form the complete musical wave in each. El86 differential push pull amplifier again at 8th aug 2008 old el86 push pull was just into junk box long time.
The circuit of this 6bm8 amplifier is sophisticated more than the previous works. The last few amplifiers that ive designed used pentodes and lots of nfb to get low distortion. The class b push pull amplifier is almost similar to the class a push pull amplifier and the only difference is that there is no biasing resistors for a class b push pull amplifier. Presenting a new outputtransformerless circuit with direct coupling to the loudspeaker. Pushpull outputs are present in ttl and cmos digital logic circuits and in some types of amplifiers, and are usually realized as a complementary. I cant give a definitive description of the 6c33cbs attributes because i have only heard it in this set amp and never in any pushpull design. This means that the two transistors are biased at the cut off point. Thus far he had been using a pushpull amplifier, but i think i. Designed as a regulator tube in electronic voltage stabilizers. Developed and prepared for release in the late 50s in the union, svetlana leningrad. Vt52b 6c33cb pushpull end power amplifier mj magazine 2008 july pdf file.
The amplifier in the article didnt use the original philips circuit, as can be seen in the circuit diagram this is a classic single ended push pull stage as is described by valley and wallman in vacuum tube amplifiers, this circuit has the disadvantage that the tubes. You can replace the el34s with kt66, but the sonics will be degraded. An amplifier that uses two amplifying elements in this type of arrangement is often referred to as a pushpull class b amplifier because one device pushes current into the load and the other pulls current from the load. The little 5881 tube leaning against the transformer is to show size. Transformation of the highimpedance and lowcurrent tube plate circuit into the. On the other hand, in a pushpull amplifiers output transformer, the. If four 6c33cb tubes were used in this particular configuration, biased at 145 v and 400 ma each, the openloop i. The pa12 uses only 2 tubes of type 6c33c to provide 25w of output power. Pushpull class b and class ab amplifiers analog devices.
But, my opinion is that the output tube via almarros design is extremely neutral and powerful with a crystal clear view on the musical material. Anyone building this circuit should spare no expense on the output transformers. Assuming classa pushpull operation, the two 6as7 triodes realize a. The deciding factor here is the type of output network. The output power and operating voltage cannot conveniently be decided independently of each other as shown in equation 2. Very few designs differing from these two have proven fit for real life, the quad ii being a notable exception you will find the diagram in the appendix together with a brief explanation. The class of operation has been specified as class c. This great amplifier is a classa, pushpull amp using a pair of 6b4g directlyheated triodes as the output stage. I am doing try to build up el86 dif pp amplifier same chassis again. The main characteristics of the 6c33c is that it has very high transconductance, high current capability and low internal resistance and also as the tubes were intended for use in military aircraft they are mechanically very robust. While going around in akihabara in tokyo i found several companies that sold tube amplifier kits, one of these companies was sanei that had many kits using tubes like 2a3, 6b4g, 300b, 6bq5, kt88 and others. While you are at it, explain what happens, when one output tube cuts off, to the half of the output transformers primary, when it completes no current path to the ground or to any other portion.
This kind of amplifier can enhance both the load capacity and switching speed. The amplifier in the article didnt use the original philips circuit, as can be seen in the circuit diagram this is a classic single ended push pull stage as is. The amplifier stage is based on the compact hifi power amplifier. Optionally a traditional push pull amp could be built for audio, but i dont have any transformers for that. El86 push pull triode connection differential amplifier. Illustration of class b and class ab pushpull, inverting amplifier output current and voltage characteristics of the pushpull, inverting amplifier rl 1k. The ultralinear or distributed load method of operating a pushpull output stage in an audio amplifier has been known for some years now, and was first employed in a commercially produced amplifier just after the war. Thus far he had been using a pushpull amplifier, but i think i convinced him that the singleended is something different. Heater voltage vf 6,3 v heater current if 760 ma fax. Mr dakesue in japan was the first person to design a 6c33cb otl power amplifier circuit in 1997. It is also affected by whether your choice of circuit forces you into class a operation all power tubes always conduct, or whether class ab half the tubes may. With the screen grids connected to taps on the primaries at 33 or 40% in general the amplifier is in an ultralinear configuration circuit 2.
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