6l6 tube amp design pdf

Acrosound vacuum tube stereo amplifier improved design. The power transformers heater winding would need to be able to provide the extra 0. If the measured voltages are correct, then turn off the power supply, and wait until all the capacitors discharged, few minutes later. Using 6 as a guideline, the following models were used in spice simulation. In looking for a tube amplifier to build for this course, i had very little experience working with tubes so i started looking at some of the original designs from fender and gibson.

It uses a power transformer scavenged from a fisher 400 receiver and hammond 1645 output transformers, and produces 25 watts per channel. Paradoxically it is possible to use a better output transformer in a given tube amplifier design and get worse performance due to the wider bandwidth of the transformer allowing oscillation to occur where it did not before with a lesser transformer. The williamson amplifier is a fourstage, pushpull, class a triodeoutput valve audio power amplifier designed by d. However, despite its lower output, we treat the sovtek 5881 wxt and 5881 6l6 wgc tubes as direct replacements for a 30 watt 6l6gc. Jan 05, 2010 and el34 and el84 tubes just enhance natural amp distortion so nicely and drive the amp so well. Low wattage 6l6 amp tube amp information, guitar amp. But for the best load, you need to connect your 8 ohms speaker in the 16 ohms output 6l6 in place of a 6v6 for the best bias, you need to change the cathode resistor. Creates the high voltages used by the 6l6 output tube. Download a pdf schematic of the amp wiring, the driver pcb schematic showing components for this build, and the power supply pcb schematic. Chances are if an amp uses 6l6 style output tubes, it has sovtek 5881s in its sockets. Figure 2 shows the schematic of the tube amplifier. Master the basics of preamp, power amp, and power supply design design your amp using a structured, professional methodology know it works by measuring performance at every point in the amplifier tv front to narrow panel to brownface to blackface reverb.

There is only one tube family that has the right tone, the 6l6 family. These are a good choice for vintage tube amps like the bassman, twin or super reverb, just to name a few, and are great in many new amps as well. Please visit my tube amplifier forum heres the place you can go to ask tube amplifier questions. The possibility of running 6l6 power tubes in a 5e3 tweed. Nos jan 6l6wgb was also an excellent sounding tube. I used a pushpullparallel set of 5b854m tubes, which are basically 807 tubes in a slim bottle with a loctal base. In 6l6, there is an electronic lens that focuses electron beam onto its plate.

The 5e3p tweed proluxe features a dual 6l6 tube pushpull output stage and fixed bias. The design allows not only the 6v6 for which it is specifically designed but the 7408, 6l6, 5881, 6f6, and 6w6 as well. The output tube type had very little to do with anything. The power amplifier involves three stages, two of which use a 12ax7, and the last of which runs through an el34 pentode tube. This kit employs commonly used pentode 6l6 6l6gc 6l6gcr vacuum tubes for the output stage of a class a amplifier with 12ax7 as input stage. These books gave a background on vacuum tubes and also their applications to guitar amplifiers. What i decided on was to build a singleended fender 5f2a princeton amp with the resistor and capacitor values from a 1957 gibson ga5 skylark amp. Most amps that i have seen that are that low are 6v6 or el84 designs. The design of this stage takes skill and care as explained in my earlier paper. A much improved design using two 6sn7 drivers and kt66 output tubes. Are there any good low wattage 6l6 designs that i could build on. The tad 6l6wgcstr has the warm lower mids and smooth top end. The common varieties use inferior insulation on rf in the base.

The 6l6 is a power amplifier tube of the allmetal type for use in the output stage of radio receivers, espe. While it is common to see them in the same types of amplifiers as an el34, the el84 is also commonly used in amplifiers with a class a design, such as the vox ac15 and ac30 class a amps are a simpler output design that typically provide a sweeter and. El84 tubes are used for lower wattage amps, typically in the 15 to 30 watt range, but have essentially the same sonic flavor as el34 tubes. Built to rigid military standards, the 5881 will tolerate higher voltages than any other 6l6. B small noval base power tubes for 10 to 15 watt amps. Pp2012 kt88 hiend push pull amplifier audio design guide. The original circuit, published in 1947 and addressed to the worldwide do it yourself community, set the standard of high fidelity sound reproduction and served a benchmark or reference amplifier design throughout the 1950s. It also results in a more efficient power output which is why a pair of tubes in these amps can produce 65 watts. Hes been using a 6l6 stereo amp every day for more. Please see the substitutes at the top of the page for more details. Thus, i was able to use my preexisting knowledge of amplifier design, coupled with. Any of these 6l6gc tubes will work well in an amp calling for 6l6 type tubes. Keep those filaments lit, design your own vacuum tube.

The 6l6 was released in 1936 and was first announced on page 50 of the may, 1936 issue of qst magazine. The circuit structures seen in bjt and fetbased amplifiers commoncollector and commonemitter, common source and common drain, are paralleled in tube based circuitry commonplate and commoncathode. Amplifier basics and vacuum tubes tim hoernings lectures and. It is still in use in audio applications, especially electric guitar amplifiers. The 6l6gc is a type of beam power tube employing a beamconfining electrode at cathode potential in place of an actual suppressor grid. The reason this works is that guitar amps are not designed to run their tubes at %100 of their rated output. Keep those filaments lit, design your own vacuum tube audio. In guitar amps we purposely push the output tube beyond their design limits to make them distort.

Built to rigid military standards, the sovtek 5881wxt will tolerate higher voltages than most other 6l6 tubes. On the surface, an el84 tube is essentially a scaleddown version of the el34, providing lower output volume and having a lower headroom. With this single tube, my mp amp is now as authoritative as my pricier el34based coincident dynamo amplifier. Pspice spice simulations are a valuable tool that aid in the design of tube amplifiers. An easily constructed highquality singleended 8w amplifier. As you use your tube amp, tubes wear out due to the heat it. Jan 21, 2020 i believe the bjt tube cascode design is essentially a class b power amp so idle current through the outputs is lower than you would normally bias a ab class amp. Jun 04, 2014 my dad built several amps over the years and has another two big amps a marantz design and a mcintosh design in partial build. Fat when the amp starts to break up, but at moderate levels is. Mullard ltd reference manual of transistor circuits, 2nd edition, 1961, pp.

How the 5e3 works rob robinettes car and tube amp website. Note that a 6l6 model was used in place of a 6v6 because it was readily available. The sovtek 5881 delivers a warm, round tone that sweetens any vintage or modern guitar amp design. Each tube sample was installed in the same custom built, fixed bias singleended guitar amplifier see schematic with a fender black face style preamp circuit. Available both as web pages click the title and, in a few cases as pdf files for. Fi enthusiasts in the construction and use of valve operated audio amplifiers, and additional.

Nov 02, 20 pushpull 58816l6 amplifier this was the second amplifier i built for myself and was completed in september 2006. Fortunately, it is very simple to build these amplifier circuits when good tube circuits and good output transformers are available. The signal flow is identical to the 5e3 and is shown using orange arrows. The beam tetrode design of the 6l6 allowed rca to circumvent philips pentode patent.

Remember, all our power tube sets include free burnin for stability and reliability. Because of this, there are many versions by different manufacturers. If your mesa amp has this option and you are considering venturing into experimental mode, there are a. Jan 15, 2019 the 6l6 tubes can produce about twice the power produced by 6v6 tubes, and are famously known for their big american sound, bold and solid voice with firm lows and prominent highs. A typical power transformer for use with 5e3 might have its 6. Even though 6l6 tube is used primary in guitar vacuum tube amplifiers, many manufacturers use this tube in audiophile designs. This author shares with us his design of a highquality audio amp that produces 180w mono, bridge or. The leads from the tube elements to the base are long enough to cause instability, which was cured in the 807 to some extent by internal shielding, and mounting the tube socket below the chassis one inch or so. I like 6l6 s more than any other power tube that i have used. The plate voltage is about 320 volts and the output stage is a classic singleended cathode follower. The preamp and long tail pair ltp phase inverter are 100% ab763 vibroverb but the power amp uses a single, cathode biased 12au7 power tube wired in true pushpull. If your mesa amp has this option and you are considering venturing into experimental mode, there are a few important things you should know. The phasesplitter is a very critical part of the pp amplifier, and its behaviour is of great importance for the performance of the amplifier.

El84 6bq5 c large octal base power tubes for 30 to 100 watt amps. I decided to build this small single ended amplifier based on 6l6 vacuum tube using a classic three stage single ended design. Singleended classa tube amplifier design and construction. The el34 tubes produce a little more output than the 6l6 s, and are characterized by a juicy voice with crunchier mids and softer lows compared to the 6l6 s. It seems to possess virtually all of the attributes i love about the 6l6 familythe elasticlike punch of guitar, the almost unparalleled ability outside of directly heated triodes to capture the warmth.

Original tungsol 5881 from 1950s was legendary in its tone. Thats it for the signal path, now lets examine the amps power supply shown at the bottom of the schematic. Check out our 6l6 tube catalog page for 6l6 tubes we stock. Figure 2 shows the schematic of the tube amplifier i used for all the tests. Custom power tube enter tube max power in watts and filament current draw in amperes only considered when no tube type is selected. Gec, alldatasheet, datasheet, datasheet search site for electronic components and semiconductors, integrated circuits, diodes, triacs, and other semiconductors. Following the introduction in july 1936 of the 6l6, the potential of the. After reading these books, i felt that i was ready to start designing the amp. The sovtek 5881wxt tube is a reliable beam tetrode delivering a warm, round tone that sweetens any vintage or modern guitar tube amp design.

Biasing an amp requires some knowledge of tube amp circuits and experience with high voltage. Jan 16, 20 this pin was discovered by amplified parts. Ac wall power from the power cord flows through the onoff ac switch and on to the power transformer shown at bottom center which steps up the wall voltage to 325 volts rms root mean square average ac for the high voltage supply and steps it down to 6. Schematic of the loftinwhite 2a3 singleended tube amplifier.

A class a amplifier is defined as one in which the output device is conducting for. Master the basics of preamp, power amp, and power supply design design your amp using a structured, professional methodology know it works by measuring performance at every point in the amplifier. Loftinwhite 2a3 singleended triode tube amplifier schematic. If you use distortion less often, you might want to consider the 6l6 and 6v6 tube amplifiers. Another problem with the 6l6 is that it is designed as an audio tube. Design my design involves a fourstage preamplifier, which uses two dualtriode 12ax7 tubes. Beam pentode for af power amplifier applications, 6l6 gc datasheet, 6l6 gc circuit, 6l6 gc data sheet. If you are uncertain that you are experienced enough to work on a live high voltage amp, please take your amp to a professional to get it biased.

There are hundreds of pages of tube amp information on my library page. In fact, i did all this research to design a special series of new toroidal output transformers, the socalled specialist series. Once our driver stage was optimized, we added an output stage to the circuit to amplify the current for the speaker. 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. Schematic for 6l6 single ended amplifier with 6n3p srpp driver. The crystalclear clean tone and infinite headroom of these amps is a great foundation to add pedals and get any sound that you want. Universal system and output transformer for valve amplifiers. The difference between a svetlana 6l6 and an rca 6l6 is the difference in the way the tube sounds when it is pushed beyond its design limits. This tube is commonly found relabeled by fender and groove tubes to gt6l6b. Rr763m blackvibe micro this is the one watt, 12au7 pushpull power tube version of the blackvibe that is perfect for true bedroom level practice and studio work.

The 6l6 revolutionized power tube design by forming the electrons into beams and using aligned control and screen grids to limit grid and screen currents. Coming into the project, i knew that i wanted an amp with roughly 60 watts of output that had two preamp channels with separate tone controls. It uses a higher voltage output gz34 rectifier tube to give the 6l6 power tubes the higher voltage they like. Jul 24, 2016 pp el34 tube amp schematic by mullard with dynaco a420 ef86, 6cg7 input 50 watts, pp, classab1 6l6, 5881, kt66, 7027 beam power pentode. The 6l6gc is a beampower pentode primarily designed for use in audio frequency power amplifier applications. At the time philips had already developed and patented power pentode designs, which were rapidly replacing power triodes due to their greater efficiency. To get 60 watts output, i decided to use two 6l6 beam power pentodes in a class ab1 pushpull but. The inside of a combo tube amplifier is a superabusive environment for tubes because you crank up the volume, create a huge amount of sonic vibration, directly couple the tubes to the chassis of your amp and then. 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. The switchable bias feature in mesa amps allows the user to choose between 6l6 or el34 power tubes with just the flip of a switch and once the corresponding tubes are installed. That is the reason for all the frequency compensation networks in that kt88 schematic above. In combination with the driver tube variations, this is a total of 42 different driverpower tube combinations.