Covers tube theory, tuned and untuned amplifiers, oscillators, and power supplies. In fact i think of that stuff since a really long time now since the first amp, i ve built ten years ago. Load line analysis was used to determine the behavior of this stage. Petersburg, russia, and is designed to be a direct replacement for any el34 6ca7 or equivalent. Both are valves which can distort really sweetly when pushed hard, the el34 being perhaps a bit bolder, the el84 quicker to smooth into overdrive. Mullard circuits for audio amplifiers primary windings. Posted on 20170905 by steve graham in amplification, tubes 19 comments. An easily constructed highquality singleended 8w amplifier using standard valves and the. If you want el84 single, 6l6 or el34 is recommended from experience. Tubes two jj el34 power amp tubes, seven jj ecc83s preamp tubes dimensions and weight height. Substitutes are given as a guide only please refer to original manufacturers data sheets to ensure that a substitute is safe and appropriate for your application. This circuit has been reengineered with many unconventional features. The el34 power tubes deliver signature harmonic overtones, with more dynamic compression and saturation that evoke a more modern british sound, all with the sustain and versatility expected from evh 5150iii amps.
If youre interested with classic circuit and classic components, then you should try this circuit. A tube amplifier chassis contains lethal high voltage even when unpluggedsometimes over 700 volts ac and 500 volts dc. If you want it done right, there are more resistors under the board to change the amp to el34 specs. Mullard el34 pushpull tube amp schematic dynaco a420 transformer. In the good old days it was difficult to design a powersupply with an output resistance low. The circuit above is complete circuit contains tube amplifier circuit diagram and power supply circuit diagram. The first stage, 12au7, offers a usable signal level for the next stage, the driver stage. There is a lot schematics on the internet, but finding a good one is pretty hard.
This amplifier was featured on the january 2003 issue of the highfidelity audio. The choice of a driver tube is the 12ax7 which is a common small signal tube. Marshall tube amps are the most wellknown el34 tube guitar amplifiers but there are many others who arrived on the scene in later years. An easily constructed highquality singleended 8w amplifier. Please visit my tube amplifier forum heres the place you can go to ask tube amplifier questions. Singleended classa tube amplifier design and construction. Vacuum tube el34b, tube amp doctor antique electronic. Especially striking is the large outputpower capability of the superpentode circuit 5, delivering up to an. This amplifier was originally featured on the october 2003 issue of the highfidelity audio. The tube amp library of information click the link above for tube amp info, schematics, board building information, projects, mods, transformer diagrams, photos, sound clips. El34 with its american equivalent 6ca7 which in fact. Hifi el34 vacuum tube power amplifier class a desk stereo. But many people who make valve amps appear to have a limited and narrow understanding of valve physics when applied in a circuit. El34 world tube amp building information the el34 world tube amp library of information click the link above for tube amp info, tube amp schematics, tube amplifier circuit board building information, tube projects, amp mods, tube amp transformer diagrams, photos, sound clips.
El34 excels at reproducing horns and female vocals, with silky smooth texture. Apr 18, 2017 el34 single ended 2x8w tube amplifier. The amplifier worked from 1954 to 1989, whenever and went off, with an average lifespan of 15 hours a day. Other distinctive features of this ferocious amp include an ultrahighgain preamp design custom voiced for maximum.
However they share the same pinout and can be used in el34s applications if the rest of the circuit is designed to accomodate them. El84 2020 the el84 2020 is the latest all valve power amp from marshall and utilises el84 power valves to obtain that classic. Oct 11, 2011 the largest difference from the transistor amplifier to the el34 tube amplifier is the bass. This is our collection of diy and hifi audio schematics.
El84 ul pushpull stereo power amplifier with hashimoto transformers. The advent of stereo in these years did not improve this situation. A survey of four sets of power tubes in two pushpull amps. The largest difference from the transistor amplifier to the el34 tube amplifier is the bass. Universal system and output transformer for valve amplifiers. The output of the plate on each pentode drives a transformer in order to convert high impedance and high voltage to the low. These considerations lead me to choose el34 as my output valve. The clear and harmonic open top end allows for great clean tone and at the same time the tad el34bstr offers incredibly powerful mids and equally powerful bass. Petersburg, russia, and is designed to be a direct replacement for any el346ca7 or equivalent. Tube amp schematics, ampeg, marshall, fender, gibson, hiwatt, magnatone. A combined input stage and driver drives the output valve, and a transformer matches the valve and the speaker system.
This guide discusses all relevant aspects for an integrated pushpull vacuum tube amplifier design, including the power supply unit. The circuit is interesting but i think it is hard to find the tubes. The use of a single tube in the output stage of the power amplifier is commonly referred to as a singleended. This driver tube, a 12at7 and the output tube, an el34, pure pentode, are coupled in a loop, similar to negative feedback. Design of the driver stage is concerned with voltage amplification as well as linearity in order to provide the output section with a strong and relatively clean signal.
A 50 watt amp with two 6l6 or el34 tubes, or a 100 watt amp with four 6l6 or el34s, is. El34s is an economical method to achieve high quality sound with a minimum of driving stage components. Beside that, el34, el84, and 12ax7 vacuum tubes are used in many practical examples, to design the various parts of the circuits and to. So the transformers necessary to support an el34 or 6l6 tube arewill be in place. Lone wolf blues company single ended 6l6 circuitry. When repeating these tests with beam power tetrodes, such as the sv6550c, the maximum. Our website and phones are open, but shipping may take a few extra days, for the safety of our team. Feel free to send us your hifi audio schematics and we will add them here.
The first two things to consider when beginning to design are. Atarashi designed this amplifier based on the el84 schematic diagram published by. Gio writes in to tell us about his latest vacuum tubebased audio amplifier design, the 5751 srpp pushpull tube amp. This positive feedback is applied back to the input stage cathode from the phase splitters cathode. To make the stereo channel amplifier, build the similar amplifier circuit read more. Output tube biasing, an introduction wall of sound. Dynaco dynakit mark iii tube amplifier schematic and instructions manual for. It is relatively easy to find introductory information on how to design simple amplifier stages, and it is also fairly easy to find extremely advanced information on complex circuit design, and nearly all of it is intended only for hifi. These are important questions because they will dictate the choice of output valve which itself will dictate the design of the rest of the output stage and power supply. This tube amplifier designed in 1953 and worked from 1954 until 1989. Classic input in series and output in parallel design adds.
Atarashi chose this design because of the uniqueness of the positive feed back that the original blueprint adopted. Vacuum tubes wear out due to heat and high temperature. View all results for el34 tube amp at sweetwater the worlds leading music technology and instrument retailer. In addition to the larger pt and diagram of the amps original circuit.
Whats the best el34 amp besides 8b i am looking for a tube amplifier with 4 tubes of el34 pushpull. A survey of 4 sets of tubes in 2 pushpull amps by steve graham. Check out the schematic and note the differences between the us 6550 circuit and the uk el34 one. Tube amp information, guitar amp schematics, tube amp. An easily constructed highquality singleended 8w amplifier using standard valves and the lundahl ll 1664 output transformer claus byrith 2002. No, i didnt powerup with one of each installed and yes, i had four of each of the above tubes for the shootout. Note that the 6ca7 el34 vacuum tube is, in actuality, a pentode tube, although it is shown in the schematic as a tetrode.
El34 s is an economical method to achieve high quality sound with a minimum of driving stage components. Just because the tube fits the socket, doesnt mean the amp runs the tube. It has an international octal base indicated by the 3 in the part number and is found mainly in the final output stages of audio amplification circuits and was designed to be suitable as a series regulator by virtue of its high permissible voltage between heater and cathode and other parameters. Pushpull kt88 class a amp with universal driver pcb diy tube amplifier schematics ax84. Good information about kt88 tube power amplifier class. They arent exactly just different sized versions of each other, one simply having out double the power output, but they are like fairly close family. The 520 was published in order to promote the new output pentode el34. For example, in marshall amplifiers el34 devices are used commonly while fender amplifiers generally use 6l6 or 6v6 devies. How to design valve guitar amplifiers the valve wizard. Experience total control, along with the same lethal looks and ferocious el34 tone of the 100watt head. The clear and harmonic open top end allows for great clean tone and at the same time the tad el34bstr. It have to be experienced as a description is far from enough compared to feeling it in your chest. A great sounding el34 amp is a joy to listen to all day.
Never touch the amplifier chassis with one hand while probing with the other hand because a lethal shock can run between your arms through your heart. Atarashi designed this amplifier based on the el84 schematic diagram published by rogers in england. Jan 20, 2018 description 2 x 12w tube amplifier with el34 and dynavoice dm6 loudspeakers. Tubes used in the aq are currently manufactured by several factories. In the tube audio world, it was companies like dynaco, leak, and mullard among others who help boost the el34 tubes popularity. Pp el34 tube amp schematic by mullard with dynaco a420 ef86, 6cg7 input. After many years designing single ended amplifiers i have decided to start a series of test about the push pull amplifiers. Beside that, el34, el84, and 12ax7 vacuum tubes are used in many practical examples, to design the various parts of the circuits and to compute the values of the needed components. This upgraded version added preamp output function. The anodes are connected to the primary winding, the cathodes to ground circuits 1, 2, and 3, and the middle of the primary to the highvoltage supply. Octal power tube max plate watts 25w sensational new highgain el34 tube with a very dynamic tone. We carry premium hand selected vacuum tubes for guitar and hifi amps. These range from a 3w singleended amp to a 20w pushpull power amp, including the outstanding mullard 510 design.
This is demonstrated by the bewildering and illogical variations of valve amp designs including basic circuit design mistakes, particularly with power valve biasing. The project details the build of a singleended 6l6 harp amp. The drive circuitry of the control grids is not shown i assume perfect. I shall not give you a step by step building manual, only some guidelines. The tube data is available on the new sensor website. In an effort to give a little back to the internet harp and tube amp communities, i have decided to offer this free project. A push pull valve amplifier almost invariably follows one of the two schemes. Vacuum tube el34b, tube amp doctor antique electronic supply. Even with just 5 w amplifier the tube amp sounds awesome sound structurally thin vacuum tubes tend to have thin sound. In each amp, anode a2 of the lower tube b4 is connected to the lower tag 1 green. May 20, 2010 but many people who make valve amps appear to have a limited and narrow understanding of valve physics when applied in a circuit. Figure 1 shows several pushpull tube amplifiers only the power tubes and the output transformers primary winding. Mullard tube circuits for audio amplifiers mullard on.
The el34 tube is a classic, wellestablished and stable design. The original amp had an outputlevel meter, being driven from the ot secondary, via a small tube rectifier. Tubesforamps is your source for replacement vacuum tubes. Are kt88s interchangeable with el34s the gear page. If you have not been trained to work with high voltage then have an amp technician service your amp. Class a single end el34 tube integrated amplifier hifi stereo vintage tube amp. The two pre amp tubes are ef804s, essentially the same as ef86s, but with a somewhat different pinout. What sound are you looking to get from the power amp, and how much output power do you want. Keep in mind, that by using pedals, you can make one amp sound pretty much like any other one, so this discussion is focused on how a few of the most popular power tubes differ from each other when using the amp, and not the pedals, to get your sound. In the circuits 117 i used el34 power tubes at 370 v high voltage supply with a quiescent current of 50ma per tube.
Due to its narrower profile, el34 tubes can run quite hot and tend to. Other common substitutes for el34 vacuum tubes are 6ca7 and kt77 tubes. This is the circuit diagram of 35w tube power amplifier with el34. I was tempted to retain it, but for the sake of simplicity, i have chosen to drop it. Instruction book for specimen single ended stereo tube amp 62718. There are hundreds of pages of tube amp information on my library page. El34 is very famous tube and great for power tube amplifier. The valve wizard single ended how to design valve guitar. Singleended tubebased guitar amplifier by joe linn senior project. Mullard el34 pushpull tube amp schema avec dynacoa420. Resistors with names such as rgain1 and rgain2 represent potentiometers, with the node between the resistors being the wiper. Its deep as the internal hell, clear like tuned piano and makes a world of difference to enjoying music. If you have built any of these circuits, we would love to hear from you so send us your comments. Among amplifiers employing two el34 s per channel in pushpull, i suspect that a pair of marantz 2 monoblocks in good condition would outperform an 8b.
To open the amplifier simulation in the editor, click on the 2x30w el34 tube amplifier tab then click on the green pencil icon in the upper right of the view window, save the file if prompted and then follow the instructions in the schematic. As can be seen, the design of the seamplifier is simple. The first tube amplifiers were constructed with triodes, directly coupled to high impedance. Marshall jmp 220304 6550 to el34 conversion the gear page.
Hifi el34 vacuum tube power amplifier class a desk stereo audio amp diy kit 24w item description notice. Two mullard output pentodes, type el34, rated at 25w anode dissipation. Ive designed a hifi amp that uses both interchangeably. Jan 05, 2010 keep in mind, that by using pedals, you can make one amp sound pretty much like any other one, so this discussion is focused on how a few of the most popular power tubes differ from each other when using the amp, and not the pedals, to get your sound. Kt88s are not big bottled el34s, they are a different type of tube tetrode than el34 6ca7 pentode. The svetlana el34 is manufactured with the original mullard design in the svetlana factory in st. This is demonstrated by the bewildering and illogical variations of valve amp designs including basic. From schematic to ordering parts to cab design, it is all here and explained in detail. The el34 is a thermionic valve or vacuum tube of the power pentode type. Compared to the hk av630 receiver, it takes a hemi of a tube amp to provide the same bass hauling capacity of a modern solidstate receiver. Tube amp schematics, tube amp information, tube amp projects.
The circuit can be used with a variety of different power tubes without modification e. The poddwatt is a small classa stereo vacuum tube amplifier that will provide about 5 to 7 watts of high quality sound. The tubes that readers ask about most often are the el84, el34 and 6l6. It contains simple, clear descriptions of the theory of valve amplification and the design of circuits, together with practical stepbystep instructions for building a number of excellent amplifiers. The two preamp tubes are ef804s, essentially the same as ef86s, but with a somewhat different pinout. The tungsol el34b is a higher impedance el34 tube design with increased touch responsiveness and a unique clipping characteristic with a hint of the 6l6 sound. The following diagram is the circuit diagram of 20w power amplifier which build based tube component el34. This website aims to fill the gap between the two extremes.
Vacuum tubes for amps pre and power tubes tubes for amps. Second, the use of real pentodes such as the el34 is essential for achieving the large output powers as shown in table 1. Introduction a couple of years ago i met per lundahl of the swedish company lundahl transformers and his father at an exhibition in connection with an audio engineering society convention, and i tried. In audio amps, el34 tube produces that signature velvetsmooth mids.
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