Feb 01, 2017 feb 1, 2017 otl tube amp amplifier production schematic stay safe and healthy. Output transformers are large, heavy, and difficult to manufacture. This results in significant cost savings if there are no output transformers in the design. Mr dakesue in japan was the first person to design a 6c33cb otl power amplifier. It seems like a beginners physicselectronics book that suddenly has a couple of exotic tube amp circuits bolted on the end. I discuss why why you need so many tubes such as 6as7, 6336.
This page is about otl amps, strengths and weaknesses, and why not having an output transformer may ruin good music. The tube based otl amplifier poured 2a peak into the 8ohm load, which into a 72ohm load, results in voltage drop of 144vpk, which in turn equals 144. At the beginning of the year, i found this interesting scheme of tube amplifiers on a forum and decided to make it. Our otl amplifiers give a sense of musical rightness, together with a realism that reveals the unique qualities of each recording.
Because it is not easy to design a good otl circuit. Diy otl tube headphone amp kit pcb, case, extras aikido wcf 6sn7, 6bx7. Our designs emphasize simple, trouble free operation. First of all i want to really thanks bruce for his work, passion and for the design sharing. Better to use a 32 ohms speaker, the amplifier will deliver 80vpp or 28vrms at 0. Weve all seen the classic gec amp schematics, but heres the whole book. Basic theory a 21stcentury approach to understanding preamp, power amp, and power supply design fundamentals of guitar amplifier system design a structured methodolody for crafting an awesome guitar amplifier. A bibliography of must have tube electronics books. Tenor tenor audio celebrating 20 years of michel vanden. Circuit simulation a deep dive into spice tube amp modeling. At any rate, if i dont find a suitable non otl amp design that i like, i may just sell off the entire lot of 6080 tubes.
Building valve amplifiers tube electronics for you and me. As a rank beginner, i bought this book to help me understand amplifier design so i could better diagnose issues with my tube amplifiers. Words alone cannot reveal the otl tube amp experience. Conventional vacuum tube amplifier designs rely upon an output transformer to couple the amplifier s output stage to the loudspeaker. As i have already said, it measures very flat, and harmonic and intermodulation distortion are both exceptionally low for a tube amp. Following is a list of must have books for the serious tube amplifier designer. Is this the kind of current required at 150 volts, for each 150 volt supply. Regular tube amplifiers have very high voltages in them and by contrast most loudspeakers are low voltage. I was aiming for the audio gdhe9 but have reconsidered. Audio engineers and designers have been trying to build otl amplifiers since the 1950s, but they met with only limited success. My passion for highend audio design always remained and my years in television repair introduced me to horizontal sweep tubes, which became my output tube of choice in single ended, push pull and otl amplifiers.
Its basicly an amp that doesnt rely on transistors, and its the tubes who make all the amplifying. How do you really design an otl amplifier with high reliability. The transcendent otl 80w diy transcendent sound forum. The tubebased otl amplifier poured 2a peak into the 8ohm load, which into a 72ohm load, results in voltage drop of 144vpk, which in turn equals 144. In order to convert from the high voltage of tubes to the low voltage of a speaker an electronic device known as a transformer is used. Otl preamps are basically almost all common hifi tube preamps. Early otl amplifiers and even modern otl amplifiers based on these early designs typically have between 8, or 16 or more output tubes per channel. Otl amplifier celebrating twenty years of michel vanden. Valve and electronics department, 1957, 126 pages thanks to eric santanen. The amp requires the most neutral preamp and sources, and works well with tube or solid state. The back cover says that the book is the most comprehensive and up to.
That is simply a part of their early history, and has no impact on the current crop of otl amps. Such an amplifier would generate between 1200 watts and 1800 watts of heat, which is about as much heat. With its very modest price tag, this kit is an affordable step into the wonderful world of vacuum tube audio. Note more than likely it will lose you a few times, and like any good referencetraining material, rereading it a couple of times you really see how what you didnt understand the first time through starts to make sense. Tubes and circuits by bruce rozenblit inner magazines. If we avoid the work of drawing load lines on a pc screen, or exercize book, then rla class a1 load for. I want to add that this is only 1 12 wpc but it sounds like 5 wpc. This type of tube in many respects is superior to the standard array of audio output tubes currently used some of the best vacuum. It is just the actual leg names that differ a mosfetjfet from a tube model. This form of otl design carries the futterman designs pioneered by new york audio labs one step forward. The otl 1 is probably the best amp available for the tube fanatic seeking the maximum possible emotional impact from recorded music. Otl output trasformer less tube amplifiers audio design guide. But he does mean if you spend a crap load on a tube amp then its better to just go with a set amp, have slightly more power, more compatibility, and better sound for the same price of an uber expensive otl.
The data of this tube was much better than anything made before in the west and sanei of japan imported some 6c33c tubes for audio application in 1997, renaming them ec33c for the japanese consumer. Audio asylum otl asylum otl, output transformerless amplifier user group. The start with this little amplifier was the christmas weekends and all spare time i got together with the lack of parts to my power amplifier. Tubes and circuits by bruce rozenblit on inner magazines some people. In my amplifier i have used a 200va power transformer per channel. Please practice handwashing and social distancing, and check out our resources for adapting to these times. This is very much cheaper than other otl amps or good quality conventional tube amps. We are also producing hightech otl outputtransformerless amplifiers and custom made to extreme high satisfaction guitar amplifiers, including tube guitar otl amplifiers. Linear tube audio uses unique technology, superior quality, and unmatched value to create worldclass amps that sound like no other at a price normal people can afford.
Basic information on power supply design and function. Beginners guide to tube audio design book this guide will assist the novice in understanding vacuum tube technology and prepare the reader to build vacuum tube amplifiers. Feb 1, 2017 otl tube amp amplifier production schematic. Vacuum tube audio amplifier kits, otl amp kits, tube phono and line level preamp kits, low cost. Mcalister audio vacuum tube power amplifiers, high end. The 6c33c is today probably the best tube available for otl s, it is a pure triode, it can pass high continuous currents and it is relatively cheap and easy to come by, for more info about this tube see. Originally announced in 2010, the crack is an affordable tube based headphone amplifier kit offered by the bottlehead corporation located in poulsbo, washington state, usa. Ier i know this is a dc approximation, 32 volts16 ohms approx. Here you will find vacuum tube based amplifier, preamplifier and headphone amplifier kits, speaker kits, finished high end tube audio products, reel to reel tape machine upgrades, parts, and one of the finest support communities on the web. The otl had two 5,000 watt regulated power supplieswhich are testament to ted hamonds engineering genius.
These amps took the world by storm as the premier tube amplifier of its time and gave tenor chief engineer, michel vanden broeck, a well served place in audio history. Such amplifiers are commonly called otl tube amplifiers. Otl amps sound great and a lot of them produce good technicalities compared to other headphone amps of similar price. Great book to get a good grasp of the ins and outs of tube audio design. Apr 03, 2019 tube amplifiers with output transformers are typically preferred due to the flexibility of headphone pairing options for the owner, however the otl design has a few significant benefits. Such designs ensure that the purest, distortion free signal reaches the loudspeakers. Our tube amps and preamps are renown for their extremely low noise and musicality. New 9718 a hybrid ss driver class a2 dht amp a 50 watt monoblock version of the engineers amp. But the sound is better than any other amp ive had by far. Tube amp design wikibooks, open books for an open world. Perfect 35 year old vintage otl tube amp by aitos duration. Diy vacuum tube valve amplifier projects hifi audio.
It is silky smooth yet possesses uncanny detail and three dimensional imaging. In addition, five projects are included that you can build. For those who use high efficiency speakers of 94db or better you will be rewarded with rich natural sound. This may be considered a beginners guide for tube audio design if you have extensive electrical experience. The most up to date vacuum tube design book currently available. Son of beast otl vacuum tube amp transcendent sound.
Amp options my otl design offers several solutions. Do they sound different and why people want tubes duration. This guide discusses all relevant aspects for an integrated pushpull vacuum tube amplifier design, including the power supply unit. Welcome to my vacuum tube audio page, which i dedicate to the reader who seeks an indepth understanding of amplifier design who wants to learn the factors that contribute to audio quality who doesnt buy the myths of the highend marketplace, where old designs enhanced with premium components and dressed up in impressive packages command astronomical prices. Conventional vacuum tube amplifier designs rely upon an output transformer. I have the berning zotltype, and i think it may be the best design of all amps ever.
Beside that, el34, el84, and 12ax7 vacuum tubes are used in many practical examples, to design the various parts of the circuits and to. The lack of an output coupling capacitor extends bass response to less than 0. An approach to audio frequency amplifier design, g. I would say that the power supply solution chosen to drive the output tubes in the otl by unknow japanese company and in the otl by yozo matsuoka from mj 199511 looks a bit strange to me, because it is designed around is a voltage duplicator where there is. I see no reason to avoid otl for reliability reasons anymore. I suggest to read this article by turner audio, has a lot of information regarding otl amplifiers. Below is a short list of some of the books we have and can recommend as good resource on the subject. He calls it zotl to differentiate it from otl, but the result is the same. In that case transformer coupled preamps are the uncommon design. Projects provide stepbystep design procedures, equations, schematics, parts lists, and photos to assist the hobbyist in construction. Otl amplifier design revisited the last schematic i posted held a few typos, which have been corrected, as shown below in redrawing the schematic, however, i realized that topology was just too big a jump for many, and that i needed to work my way up to this schematic in stages, starting with the underlying otl topology without the crossovernotcheliminating aspects of the circuitry.
Anyone that uses vacuum tubes, from the hobbyist, the musician, to the design professional, would benefit from tubes and circuits. New york audio laboratories futterman otl1 power amplifier. That is you want to amplify voltage as much as possible. Just to be clear, im not trolling you, or your company, just answering the question in the thread title, whats your otl tube amp experience and suggestion. A really good otl design makes your transducers sound like they are directcoupled to the music, and that is precisely what the feliks audio euforia does to your headphones. Otl tube amps are peculiar, uncommon designs that go to great lengths to avoid using ots.
In a word, amplifier speaker interaction effects are especially unpredictable. Usually when you design tube amps you design with regard to common cathode cc. This new design to reduces cost without any sacrifice in performance. The otl is a unique design concept that is different than traditional vacuum tube amplifiers. Seventeen amplifier designs ranging from 3 to 1,100 watts are presented, along with tube data and design considerations. When you hit the above link you will probably understand the difference. The company was created by the president for life dan doc b schmalle in the mid1990s, and primarily offers diy tube audio kits for both headphones and home stereos. We get a lot of people asking us for diy audio and loudspeaker book recommendations to get them started in the hobby. Diy audio books and manuals speakers, vacuum tubes, electronics. We also have a world class tube line level preamps and tube phono preamp. With precious little valve electronics in the book, it certainly is not the most up to date and comprehensive vacuum tube design book currently available. Otl output trasformer less tube amplifiers my consideration on problems of each design. Otl asylum otl, output transformerless amplifier user group.
Discover stepbystep how to design phase inverters and power amps to achieve your specific design goals. Until 1954, julius flutterman first came up with his patented otl design which aroused the audio electronic world op iron can then be disposed. This does not mean that the otl 1 is colored in any normal sense of the term. Guitar amplifier power amps helps you get the most out of it.
Transformation of the highimpedance and lowcurrent tube plate circuit into the highcurrent and low impedance needs of a. Tubes and circuits is a condensed engineering manual that teaches the theory and operation of vacuum tubesas well as circuit design. Given the 72ohm load, the solidstate power amplifier was voltage limited. Hifi el84 vacuum tube amplifier integrated class a singleend stereo audio amp. The basic steps of power amp design 19 the commoncathode amplifier 19 the dc operating point 20 using triodeconnected curves 21 vacuum tube response to ac signals 23 cutoff and saturation 23 setting the dc operating point 25 the ac load line 26 optimum load line for pentodes 30 screen dissipation 33 maximum power and headroom 35 dc grid bias. The new otl designs on sale here from transcendent are low power in comparison to the old one, so im quite confused. Tenor makes hybrid tube amps an update to their hybrid 300 mono blocks i owned briefly in 2004 now. By stating you made the first reliable otls does indicate that some or all of your predecessors were in fact, not reliable. Some of them are long out of print, and can only be obtained from used book sellers, although they are occasionally seen for sale on the internet. All of the theory is put to use and made practical in the project chapters. This inexpensive tube amplifier kit has been available for a number of years now and makes for a nice little tube amp. My amp shown above 10 wattschannel by berning no longer in production, alas is singleended, and in actual use is like an otl type amp the best of both worlds. Fleming used the principle to design the diode, the first vacuum tube.
Another problem was how to realize a symmetrical output stage when tubes do not come as complementary npn and pnp pairs as with transistors. This gives some unique features like giving more power the higher the impedance, the tube may or may not color the sound, and theres a high output impedance, so it doesnt pair well with low impedance headphones. Only a tenor amplifier renders the music the way it was originally recorded. Im really interested to build a the transcendent otl 80w from audio reality book, but im wondering if it does have any sense nowaday. Back to otl designs for us tubeloving folk, the ideal tube power amplifier would be both output transformer and coupling capacitor free, the. The acronym otl refers to a tube amplifier that is output transformerless. The author systematically steps through single one stage amplifiers, simple gain circuits, negative feedback, output stages and transformers including single ended types. Qtron pa12 otl tube amplifier delivering the full promise of otl technology. Transcendent sound single ended otl amplifiers user. Instead, otls use one of two primary methods for output stage coupling.
Review by dick olsher even 60 years after the concept gained some traction, the notion of an output transformerless otl tube amplifier still seems mind blowing. Qtron pa12 otl tube amplifier delivering the full promise of otl. After design of layout i ordered the necessary parts. The dynamics of power amp distortion create the heart and soul of an amplifier. It is the foundation of our success and the reason tenor amplifiers sound so perfect and become the last amplifier you will ever want or need. Qtron pa12 otl tube amplifier delivering the full promise.
A power output of 15 watts per channel will drive many highperformance loudspeakers on the market. The other speaker design thats often teamed with an set amp is the singledriver speaker thats close to 100db efficient, has no crossover, and has very easy impedance curves. Output transformerless otl is a type of vacuum tube audio power amplifier, which omits an output transformer for the purpose of greater linearity and fidelity. He specializes in otl no output transformer amplifiers that produce maximum fidelity. There are a lot of books on the topic and naturally we cannot go over all of them all. Conventional vacuum tube amplifier designs rely upon an output transformer to couple the amplifiers output stage to the loudspeaker. Dec 30, 2006 otl amplifier design revisited the last schematic i posted held a few typos, which have been corrected, as shown below in redrawing the schematic, however, i realized that topology was just too big a jump for many, and that i needed to work my way up to this schematic in stages, starting with the underlying otl topology without the crossovernotcheliminating aspects of the circuitry. The initial intent was to design an otl amplifier that i saw in the back of a bruce rozenblit amplifier design book. First, in order to protect the loudspeakers in the event of a fault, it needed to be naturally current limiting without using auxiliary protection circuits.