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1 Designing Vacuum Tube Amplifiers And Related ...



The MC3500 Mk II is powered by eight EL509S high-power output vacuum tubes. The EL509S tube was chosen specifically due to it having many similar qualities and characteristics of the 6LQ6 "sweep tubes" used on the original MC3500. Like the 6LQ6, the EL509S is very rugged thanks to its robust cathode and associated heating element which produces a high peak plate current capability in excess of 1 Amp.




1 Designing Vacuum Tube Amplifiers and Related ...



Sweep tubes like the original 6LQ6 were primarily designed for 1950-60s era TVs where they would sweep the cathode ray gun in the picture tube across the phosphor screen. This was a very power-hungry process that required these high-powered sweep tubes. The use of sweep tubes by McIntosh engineers in the original MC3500 amplifier was a very cool and innovative application. By using the high-power EL509S vacuum tubes, the MC3500 Mk II amplifier remains as faithful as possible to original MC3500 output design. In addition, just like in the original MC3500, the MC3500 Mk II uses an additional feedback loop to enhance the linearity of the output tubes.


Tech TourThe Dragon Inspire IHA-1 is a single-ended vacuum tube design that has its inputs directly coupled to the grids of two 6SN7 dual-triode tubes with only a selector switch and volume control between the inputs and the tubes. The IHA-1 has only three tubes total in its circuit, two 6SN7 dual triodes and one 5Y3GT rectifier. The IHA-1 can also be configured with different dual-triode tubes, such as a 6BL7 or 6BX7 (with the 6BX7 you lose some output power) and different rectifier tubes, including a 5Y3, 5U4, or a 274B. Because the 6SN7 tube is a dual triode, it allows the IHA-1 to have two gain stages, powered by each section of the 6SN7. While the IHA-1 is not a true dual-mono design because the right and left channels share the same power supply, the two channels remain separated throughout their signal path.


Some headphone amplifiers are designed to be general-purpose devices, with multiple gain and impedance adjustments, while others are made to work best with certain headphones that fall within a more limited specification set. The IHA-1 is definitely one of the latter. Dennis Had told me that the two headphones he used when designing the IHA-1 were the Grado PS-1000 and Audeze LCD-3. My experience is that the IHA-1 is better suited for medium- and low-sensitivity headphones than anything with sensitivity greater than 90dB. With higher-sensitivity in-ear monitors, the IHA-1 has a noticeable hiss that obscures low-level details. Some of the headphones that were too noisy for my tastes included the Oppo PM-3, Audeze EL-8, and virtually every in-ear monitor in my collection.


"The art of Electronics" is often adviced as a basic, non-academic textbook for beginners and for all the enthusiasts. It is referenced also in several questions like this one. But in the Table of contents it does not have a chapter dedicated to vacuum tubes.


There are a number of great vacuum tube books, but it kind of depends on what you want to do. If you're doing guitar or hifi amps, I would highly recommend the appropriate book (he has one for each) by Merlin Blencowe (a.k.a. Valve Wizard). He's an exceptional writer who's very good at making tubes VERY easy to understand.


The most complete and practical modern reference on audiophile vacuum tube technology! Destined to become a true classic in its field, this unique DIY design & construction manual presents the theory and practice of amplifier design & construction in a balanced way.


Although the focus is on audiophile or "hi-fi" vacuum tube amplifiers, those interested in tube guitar amps will also benefit from the wealth of material presented, most of which directly applies to tube guitar amps as well. Apart from various audio circuits, electronic components, power supplies and tests & measurements are also covered in depth. Even tube testing and tube testers are discussed at great length, as is troubleshooting, repairing and modifying (upgrading) tube gear. The advanced topics that other books don't even mention, such as audio transformer design, construction and testing, make this reference manual a valuable addition to your technical library.


For those familiar with solid state devices, such as bipolar transistors and FETs, an easy and seamless transition into tube technology is provided in the book, which adopts a unifying approach to amplification and rectification devices, be they of solid state or vacuum tube kind.


This practical DIY manual is richly and professionally illustrated with photographs of tubes, components and amplifiers, circuit diagrams, tube pinouts, curves and loadlines, graphs and charts. Hundreds of such valuable illustrations make it easy to comprehend issues. There is no need to search for, download and print such information, saving you valuable time. All the information required to design and build tube amplifiers is compiled in one place.


Woo Audio is a fine audio components designer and manufacturer in New York. We sell our products worldwide and to selected dealers. Our store offers curated high-end headphones, audio cables, vacuum tubes, and accessories. Expert advises and professional services are guaranteed.


Approved return is subject to a 10% restocking fee on Woo Audio products. A 15% restocking fee on vacuum tubes, headphones, cables, accessories, and all non Woo Audio branded products. Confirmed defective products are not subject to restocking fee.Only confirmed defective products can be exchanged for the same item or another product. Cost differences are adjusted accordingly by Woo Audio. A credit or a refund will be applied if the replacement item cost less than the item for exchange. Customer is responsible for paying the difference if the replacement item cost more than the item for exchange. Customer pays shipping on all exchanges.


The principal limitation imposed on the design was that it had to beconstructed on a Dynaco PAS chassis using the original power transformer,whose high voltage winding is specified at a wimpy 10mA. I squeezed a littleextra current out of it by using a separate filament transformer mountedon the back,5 but I was still limited to six tubes (two in newsockets mounted in chassis holes behind the line amplifier PC board). Thetubes must be 12AX7s, which perform well at plate currents around 1mA,lower than other popular tubes used in preamplifiers (12AT7, 12AU7, 6DJ8).The 12AX7 is ideal for use with negative feedback (local or global) becauseof its high amplification factor (mu). A high-mu tube with NFB has muchmore precisely controlled gain than a low-mu tube without NFB.


The attractive blue meter is flanked by two rows of output vacuum tubes that bring even more visual appeal to the front panel to go along with the knobs and brushed aluminum handles that all effortlessly blend with the polished stainless steel chassis. The MC2301 is well suited for stereo music systems.


Valve amplifiers pose special challenges for the output transformer and power supply. Obtaining the best performance involves very careful design of the transformers, and an idea that "seemed like a good idea at the time" can cause major problems in use. Chief amongst these is the choice of rectifier for the power supply. Valve (tube) diodes have the inevitable nostalgia value, but they are fundamentally one of the most useless components you can include in a power supply.


Valve rectifiers do provide one small benefit, in that the HT supply gets an automatic soft-start as the heaters or filaments take time to reach operating temperature. This may be an advantage in some circuits, but if a delay is needed it's far better to do it electronically (using a MOSFET for example) than to use a vacuum tube rectifier with its many faults and limitations.


As noted earlier, valve rectifiers do provide a small benefit - the HT supply gets an automatic soft-start as the heaters or filaments take time to reach operating temperature. This may be an advantage in some circuits. If a delay is needed to allow the output valves to reach operating temperature before the HT is applied, do it electronically using a MOSFET, rather than using a vacuum tube rectifier with its many faults and limitations.


Regardless of the mythical qualities that are all too often attributed to vacuum tubes, they are still components that can be damaged and wear out over time. Much like with transistors and kin, they come with a stack of datasheets, containing various curves detailing their properties and performance. These curves will change as a part ages, and validating these curves can help with debugging a vacuum tube-based circuit. This is where one can either spend an enormous sum on a commercial curve tracer like the Tektronix 570, or build your own, as [Basin Street Design] has done.


Moon Audio is proud to host and share the return of the legendary Dennis Had, to the world of tube headphone audio. This IHA-1 Dragon Version, stereo vacuum tube headphone amplifier maintains Dennis' philosophy reinforced over decades of listening, designing and building audio amplification.


As with Dennis' previous designs, his main concern is always the sonic purity of the output signal as perceived by the human ear. The IHA-1 Dragon is vacuum tube amplification in its purest form. It is a very clean short signal path. There are no capacitors, resistors or other passive components that make up the circuit. The signal enters the RCA jack, travels to the DACT stepped attenuator, then the 6SN7 tube, followed by the Output transformer and exits via the Headphone Jack or Preamp RCA. The Tubes become very important in this sort of circuit. The better the tube the better the end result. You can also very drastically change the tonality based on the tube you choose to use. Each tube has a very different sound signature or flavor. 041b061a72


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