This is a rebuild onto a custom made steel chassis in a wooden case. The aim of this project was to build a low cost valve amplifier with good quality sound output. Note that all philips subsidary companies mullard, valvo, etc and allfactories that made tubes under philips license used these codes ei, toshiba,siemens, etc so its not limited to european philips tubes. This tube amplifier designed in 1953 and worked from 1954 until 1989. Output pentode quick reference data anode current ia48ma.
Actually the transformer i am using now pulled from a 90s blues deluxe has a 4k primary. Pushpull pp el84 6bq5 or 6v6 6aq5 tube amp schematic. And when you connect the screen grids with their anodes, the tubes behave like triodes, and you have a pushpull triode amplifier circuit 3. Here is a design for a valve based, stereo audioamplifier, not using valves types which are expensive to procure because of their esteemed nature in performance and purity of sound for music reproduction, guitar amplifiers etc. Oddwatt project ecc802s srpp el84 6bq5 pushpull tube amplifier. The anode supply voltages are taken from the reservoir capacitor c15, while the supply voltages for the screen grids and for the rest of the amplifier are. The information provided is and remains the sole property of kennedy tube audio a. These old leak amplifiers sound wonderful when restored, but this route to. The output stage consists of two output pentodes, type el84, in a cathodebiased, pushpull circuit. Nov 02, 20 pushpull 58816l6 amplifier this was the second amplifier i built for myself and was completed in september 2006. These old leak amplifiers sound wonderful when restored, but this route to achieving amplifier excellence is not for everyone. The yaqin mc84l is a class a integration pushpull tube amplifier that uses a highperformance ultralinear pushpull circuit to bring rich acoustics out of your audio. Both tube amplifier projects use el84 6bq5 tubes and the earlier one used a ecc802s driver while this one uses 5751 driver tubes.
The circuit design uses 6cm5el36 power pentodes in a push pull ultralinear configuration, with a fixed 50 volt dc grid bias. A push pull amplifier is an amplifier which has an output stage that can drive a current in either direction through through the load. Tube amplifier with el84 pushpull stereo madexp by. This great amplifier is a classa, pushpull amp using a pair of 6b4g directlyheated triodes as the output stage. An output transformer for pushpull operation, with reactive load of 8k ohm. When large amounts of output power are required more than about 15w the push pull output stage becomes the order of the day. In common with all e prefix tubes, using the mullardphilips tube designation, it has a heater voltage of 6. Vintage rca tube amplifier amp pull from rca console el84 6bq5. Atarashi designed this amplifier based on the el84 schematic diagram published by rogers in england. I first saw this type of output circuit on diyparadise which is variation of the. Pushpull pp or tube amp schematic with dynaco transformers. The stereo 20 has a very active following and uses the sweet el84 valve in class a, push pull.
Many guitar amplifiers routinely run el84 tubes in. May 25, 2017 stereo push pull el84 amplifier which is technically finished. The first circuit in the pdf shows an archetypal, small to. The pushpull el84 tube amplifier schematic is from the book build your own audio valve. It can produce 17 w output in class ab1 in pushpull configuration. I built a single ended valve amplifier one power valve with single winding on output transformer at some point in the midlate 90s. A single el84 was used in lowcost equipment, and a pushpull pair for lower distortion and higher power. Owners of amps from dynaco, eico, mullard, and fisher, among others, were enjoying great sound from these reasonably. After the 50s, the growth of new ideas in tube amplifier circuitry declined, and standardized designs became generally accepted, such as the lafayette 2 x el84 6bq8 pushpull power amplifiers in pentode mode with a rather large amount of overall negative feedback and a 12w power bandwidth from 20hz30khz. The mini block tube amplifiers use a 5751 in the driver position and the el84 output circuit is biased into classa, ultralinear operation. By mike stehr, december 1, 20 in 2channel home audio. This arrangement allows the valves to be operated in class ab, which is considerably more.
Designed for the mullard 510 amplifier but may be used in any single ended design with a valve having an output impedance of 6600 ohms anode to anode, such as an el84. Pushpull el84 guitar amplifier suggested circuit using valvewizard universal amp pcbs. Yaqin mc84l el84 push pull tube amplifier hifi exquis class a integrated lamp amp headphone output preamplification part use srpp circuit, so the machine. This classa pushpull tube power amplifier uses a pair of pushpull class a. Homebrew 6bq5el84 sep amplifier based on rh84 circuit. This project is related to the other tube amplifier projects i have posted. Vintage rca tube amplifier amp pull from rca console. El84 guitar amplifier schematic pushpull pp el84 tube amplifier schematic with ecc83 input stage. Diy ecc802s srpp el84 6bq5 pushpull tube amplifier. Ive restored a magnavox 6bq5 el84 paraphrase push pull console amp, and those amps are great with high efficiency speakers. Prototype of tenwatt amplifier without controls underside of prototype without controls the push pull output stage of the circuit uses two mullard output pentodes, type el84. Recommend output transformer for 2xel84 15 watt amp the.
Schematic by georges matore led magazine, januaryfebruary 97. The circuit allows for adjustment of the bias the 25 ohm variable resistor but the. If youre interested with classic circuit and classic components, then you should try this circuit. Step by step design of a pushpull vacuum tube amplifier. Schematic is from the dynaco superfidelity output transformers catalog. It have to be experienced as a description is far from enough compared to feeling it in your chest. Design of push pull amplifier using vacuum tube gadgetronicx. More specifically, the design of this vacuum tube amplifier is described in details in chapter 6. Hi i am looking for a schematic for a good el84 ecc83 amp i have the valves and the ecc83 seems more applicable to a guitar amp, think about using. It has more than a casual similarity to the first pushpull el84 6bq5 oddwatt project from nearly two years ago. It is a distributed load pushpull output topology called ultralinear back in the day. El84 ul push pull stereo power amplifier with hashimoto transformers. I have a 8k output transformer without ul 2 el84 and a ecc82. His latest amplifier project shares a similar topology with the other oddwatt tube amplifier projects available on the diy audio projects website.
Amplifier service technicians listing tube amp schematics and layout diagrams everything from acoustic to wurlitzer pdf tube amp books that you can download right click on the links below and then choose save target as save the pdf files to your computer where you can find them and then read them via adobe acrobat note that these are very. Bruce heran of oddwatt audio has shared another of his great sounding oddwatt amplifier designs with the diy community. Sep, 2017 ive never heard an eico 6bq5 el84 amp, but i would imagine those to be very nice amps. High voltage capacitors and 1w resistors shown in blue. This amplifier was a gift to my fatherinlaw for christmas a few years back. El34 push pull amplifier schematic for yaqin mcs el34 6ca7 4 vacuum tube integrated pushpull amplifier i am glad to report the printed circuit board is designed to where internal. By the late 1950s there was a large selection of stereo hifi audio tube amplifiers available. On that note, what is the optimum primary impedance for a pair of el84s, pushpull cathode biased. A kennedy audio labs, and is provided with the understanding that this information is for personal use only.
Bruce heran outlines the design and construction of monoblock push pull el84 6bq5 valve amplifiers. Ive never heard an eico 6bq5el84 amp, but i would imagine those to be very nice amps. There is more information available about tube power supply design in the power supply design for vacuum tube amplifiers article. I have 95 db sensitivity speakers, so the lowish 5 watts of power produced by a triodestrapped pp el84 amp would be enough. Schema of the amplifier output stage designed around el84 tubes. Yaqin mc84l el84 pushpull tube amplifier hifi exquis class a integrated lamp amp headphone output preamplification part use srpp circuit, so the machine. The first circuit in the pdf shows an archetypal, small to medium power pushpull amplifier configuration that uses a triodepentode ecf83 in the frontend. Theres nothing on the web, and thought id ask here before getting onto reinhard. It has more than a casual similarity to the first push pull el84 6bq5 oddwatt project from nearly two years ago. A friend of mine, neal haight, who has contributed many of his great ideas to this magazine, recently mentioned a lack of articles regarding what i consider to be the king of the baby bottles, the 6bq5el84 power tube. Oct 11, 2011 the largest difference from the transistor amplifier to the el34 tube amplifier is the bass. What really kicks that nice midrange into highgear, however, is the el84 tubes, which provide a solid bottom end and shimmering highs but also allow you to really hear the. A high quality 10w at 20hz push pull ultra linear output transformer. Weve covered theory and applications behind a push pull amplifier.
On that note, what is the optimum primary impedance for a pair of el84s, push pull cathode biased. The circuit is interesting but i think it is hard to find the tubes. Mar 06, 2019 a single el84 was used in lowcost equipment, and a pushpull pair for lower distortion and higher power. However, i dont think the output transformers are built to handle the loads of quad electrostatics. I have built some pushpull amps using this wonderful, hardworking little tube, but even though they were fairly simple. The push pull el84 tube amplifier schematic is from the book build your own audio valve. Note that all philips subsidary companies mullard, valvo, etc and allfactories that made tubes under philips license used these codes ei, toshiba,siemens, etc so its. Eirc electronic tubes factory data sheet el84 page 1 of 8 telephone. I have built an 18w push pull tube amplifier using a pair of el84s and. Atarashi designed this amplifier based on the el84 schematic diagram published by. An easily constructed highquality singleended 8w amplifier. An easily constructed highquality singleended 8w amplifier using standard valves and the. Stereo pushpull el84 amplifier which is technically finished. El84 ul pushpull stereo power amplifier with hashimoto transformers.
Classa pushpull tube power amplifier electronics diy. The first circuit in the pdf shows an archetypal, small to medium power push pull amplifier configuration that uses a triodepentode ecf83 in the frontend. This amplifier, like the my other designs, can be connected directly to a cd player or to a dac without using a preamp. The el84, or commonly known as 6bq5 in north america, was intended for use as an inexpensive alternative to the larger audio tubes of the time, such as el34, 6l6, and kt66 power tubes. After the 50s, the growth of new ideas in tube amplifier circuitry declined, and standardized designs became generally accepted, such as the lafayette 2 x el84 6bq8 pushpull power amplifiers in pentode mode with a rather large amount of overall negative feedback. Rl of 200k ohm to give some margin to the resistance of the bias voltage circuit. Claus byrith l an approach and a practical circuit. Pushpull pp el84 tube amplifier schematic with ecc83 input stage.
Ive restored a magnavox 6bq5el84 paraphrase pushpull console amp, and those amps are great with high efficiency speakers. Weve also demonstrated different types of push pull amplifiers, like class a, class b and class ab push pull amplifier models. Sep 06, 2014 push pull pp el84 tube amplifier schematic with ecc83 input stage. Pushpull 58816l6 amplifier this was the second amplifier i built for myself and was completed in september 2006. We will design a hifi amplifier that provides roughly 12 watt rms, using el84 power vacuum tubes in the output stage. The very good result got with the pp2010 and availability of a pair of old 10kohm tecnotrafo italy push pull transformers have forward me to create this new amplifier. I used el84 power vacuum tubes and 12ax7 vacuum tubes as input and phase split. The most popular highend tube amps in the market top. B amplifier or modulator driven by two el34 in directcoupled cathode follower circuit see circuit, a. At the time i was given a circuit for the amp i built and a push pull amp, i never did build the pp.
This amplifier was originally featured on the october 2003 issue of the highfidelity audio. Pushpull pp el84 tube amplifier schematic ecc83 input. His latest project is similar to the first pushpull el84 6bq5 oddwatt project posted two years ago. Fisher used the 12dw7 7247 tube in similar circuit. Did some changes to the original schematic to make it less sensitive and quieter. Class ab, two tubes in push pull anode voltage va 250 300 v common cathode resistor rk 270 270. Designed for the mullard 33 amplifier but may be used in any single ended design with a valve. That is driven by a directcoupled splitload phase inverter, preceded by a single gain stage, all using the common 12au7. Tube amp schematics, tube amp information, tube amp projects. A push pull valve amplifier almost invariably follows one of the two schemes shown in block diagrams below. Version 1 uses two 6sn7s in the input stage, and delivers full output with around 300mv input. The cost of such an amplifier is determined mainly by the transformers and the audio output valves.
These yield a rated output power of 10 w with a level of harmonic distortion under normal loading conditions, of less than 0. Simple and elegant push pull amplifier circuit designdiagram and its. Also here, i designed it using the approach described in my book. Mar 17, 20 ive dug this one out from the attic, and was hoping someone could tell me what sort of power output i might expect to get from it for a little biamping experiment i have in mind.
Its deep as the internal hell, clear like tuned piano and makes a world of difference to enjoying music. It uses a power transformer scavenged from a fisher 400 receiver and hammond 1645 output transformers, and produces 25 watts per channel. For a number of years, i have been an admirer of the h j leak valve amplifiers made in the 1950s and 60s. El84, 6l6, kt66, el34, 6550a, 6sn7 types etc which typically command high prices when offered for sale. The very good result got with the pp2010 and availability of a pair of old 10kohm tecnotrafo italy pushpull transformers have forward me to create this new amplifier. Nice work the humble 6bq5, either singleended or pushpull, has become a real favorite of mine, up there with the 45, 2a3, and 300b. Ten watt amplifier the classic 510 amplifier design from mullard ltd. This arrangement allows the valves to be operated in class ab, which is considerably more efficient than class a up to 80% compared with up to 50% respectively reducing the amount of power wasted as heat in power valves. Practical implementation of the pushpull, common source amplifier method 1 c lr vin vout iout vdd m2 m1 m3 m4 m5 m6 m7 m8 vgg3 vgg4 vss fig. A stereo 17 watt per channel ultralinear, push pull amplifier using 6cm5el36 output valves. This is the circuit diagram of 35w tube power amplifier with el34.
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