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Vacuum Tube Circuits, page 1
Vacuum Tubes:  # - H        I - S       T - Z

Last Updated on:
Thursday, June 25, 2015 06:20 AM

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

25 Watt Music Amplifier -  schematic only, no description  . . .  [by IQ Technologies Industry, unless otherwise noted online]


2A3 Push-Pull Class A Stereo Amp -  The input stage is comprised of a both halves of a 6SL7 octal dual hi-mu triode in a differential amp configuration with a 1ma constant current cathode load. I'm using field-effect (constant-current) diodes for simplicity. the diff amp approach was chosen for good power supply rejection, ease of balancing, good gain, and ease of application of *feedback*, if desired (hey, i like to keep an open mind). It also takes care of phase-splitting right up front. Note: I've returned the constant current diode cathode to -9V instead of ground in order to avoid the non-linearities about the pinch-off region (Vpo ~= 1. 5V) . . .  [Bob Danielak's website]


500W 4X150A/7034 Tube 26-30MHz VHF output amplifier -  The more information about tube 7034 can be found at this address http://www. g8wrb. org/data/Svetlana/pdf/4X150A. pdf Shortly: The heater voltage 6v 2. 6Amp. You can see the yellow light in it. All metal/ceramic construction. First apply the 6v heater voltage 30 second before the anod voltage. Sufficient cooling must be provided for the anode. The best is to use an anode chimney. Air-flow is in the base-to anode direction. . .  [by IQ Technologies Industry, unless otherwise noted online]

845 20W A1 class monotriode amplifier -  This project is finalized, that means it is no longer experimental. This amplifier, altough limited in output power (20W) , has been designed to give the best listening pleasure. No compromise has been made during components choice: the 845 output triode is one of the best tube available today in that range of power for single-ended applications, the driver stage uses a 300B, a long revered audio tube (note that you must use a WE 300B or a Sovtek 300B). This technical choice has been made in some commercial (like Marantz T1) or amateur . . .  [puechmor AT mygale.org]

A DC-Coupled Tube Amplifier With Futterman Output Stage for Dynamic Headphones -  The Futterman output stage in this tube amp offers the choice of DC- and AC-coupled outputs. The class AB design can output up to 24mW into a 30-Ohm load or nearly 500mW into a 600-Ohm load. . . .  [Design by Rudy van Stratum ]


A Low-Voltage Class-A Tube Headphone Amplifier -  This OTL design features a high-voltage power supply that is less than half of the one used in the author's first amp and most other tube amps, but without compromising performance. . . .  [Design by Helmut Ahammer ]


A Single-Ended OTL Amplifier for Dynamic Headphones -  A simple OTL design that uses just two tubes (dual triodes) for stereo. It has a common cathode input stage direct-coupled to a cathode follower output stage. . . .  [Design by Aren van Waarde ]


A SRPP-Input Tube Amplifier for Headphones & Loudspeakers -  This transformer-coupled design uses a series regulated push-pull input stage and a parallel-triode cathode bias output stage. The audio output transformer is hand-wound from a kit. The amp will drive both headphones and speakers. . . .  [Design by Tony Frazer ]


A Tube Headphone Amplifier/Preamp with Relay-Based Input and Power Switching -  A tube headphone amplifier inspired by the "Top-Level" and "No-Compromise" amps of Andrea Ciuffoli, except that the output stage uses a triode-connected pentode. Because this amp also serves as a preamp, the author has put in a sophisticated relay-based switching system (both input source selection and power supply). The power supplies also feature slow-on and stepped delayed turn-on. The power-on LED doubles as a warm-up status indicator. . . .  [Design by Helmut Ahammer ]


A Vacuum Tube Microphone Preamp/ Direct Box Project -  From January 1997 EQ Column, includes phantom power supply. . . 


A Zero-Feedback SRPP-Input Headphone Amplifier -  Features a series regulated push-pull input stage and transformer-coupled output stage with an output impedance of about 2. 5 ohms. It has zero global feedback for open, natural sound without any harshness. . . .  [Design by Simon Busbridge ]


All-Triode Direct-Drive Tube Amps for Electrostatic & Electret Headphones  -  Two electrostatic headphone driver designs: the second is DC-coupled and uses high voltage Apex op-amps as DC regulators. They will drive Stax and Sennheiser electrostatic phones, and the author includes directions for adapting the designs to other models. These are "the best electrostatic headphone amplifiers currently available, anywhere in the world. " Will also drive electret headphones. Recommended only for intermediate-advanced builders familiar with high-voltage safety!. . .  [Design by Kevin Gilmore ]


Altec 1566A:Vacuum Tube Preamp & Direct Box Project -  There are all sorts of tube circuits, some of which actually deliver The Sound people associate with Vacuum Tubes.   Did you know, for example, that asymmetrical distortion generates even-order harmonics while symmetrical distortion produces odd-order harmonics?  Neither vacuum tubes nor transistors are exclusively responsible for either type of distortion, . . . 


Amp based on a Silvertone Twin Twelve -  ampbased upon an old Silvertone Twin Twelve -- I decided to try another guitar amp (actually, I intend to build two identical single 12" combo's - one for me and one for my TWIN brother, Rich). Although I'm sure a Fender Deluxe knock-off would be just fine for what I needed , I wanted to do something a bit different. . .  [from Bob Danielak's website]


Baby of Camel: All-directly-Heated Pushpull Amp-Spy Photos -  Project a Camel is a take-no-prisoners DHT PP based on Lynn Olson Aurora topology. Unfortunately, I'm stuck waiting for Lundahl transformers (three monthsthat famous Nordic attention to detailone turn a day). Well, before Camel is born, there was his baby. . .  [klausmobile @ yahoo.Com]


Bass Guitar Amp -  I've been wanting to put these EL509's to use!!! Figured a nice high-power bass guitar amp would be a perfect application. I have the amplifier built to the point shown in the schematic, above. Initial testing with tone-stack replaced with a 10:1 voltage divider is very promising. Still need to decide on the tone stack arrangement. The unit is built as a stand-alone head, and will be used with a Peavey 15" + 2x 10" Bass cabinet. . .  [from Bob Danielak's website]


Battery heaters in a tube amplifier: A simple battery switch with undervoltage protection -  This simple circuit controls 6. 3V SLA heater batteries (two batteries are shown, but it is stackable to practically unlimited number of batteries). Batteries are floating in 'on' state, paralleled in 'off' (external charger) state. If any battery voltage falls below threshold for more than 1 second, the circuit latches up in 'off' state, disconnects the batteries and shuts down plate power supply (which is normally controlled through a delay relay). Once in 'off' state, it can be reset to normal only with master mains switch. 1-second 'grace period' set by C2R2 takes care of power-on surge currents that can cause temporary undervoltage. . .  [from Klausmobile Tube Tester Files]


Brute Force In A Line Stage 100% Tube!) -  An OTL mu follower design. "One, often forgotten, purpose of the preamp is to drive headphones. I listen with a pair of AKG K240s, which is a relatively easy load to drive. This all-tube line stage and driver can power them, without resorting to output transformers. ". . .  [Design by Eric Barbour ]


Capacitive Sensor -  Special design for shop-windows animation; Useful for many types of touch controls. . .  [Flavio Dellepiane's web site]


Class A2 SE 812A Amp -  This Amp is a variation on the SE 826 amp, below. It uses positive grid bias derived directly from the cathode follower driver stage. The 6F8-G driver/input tube was chosen because it biases to the required voltage (+14V) for the output stage's bias. (Note that the 6F8-G can be replaced with a 6SN7. I just happen to like the looks of the 6F8-G better) . . .  [Bob Danielok]


Class A2 SE 812A Amp power supply -  This is the power supply for a Class A2 812A Amp. . .  [Bob Danielok]


Class A2 SE 826 amp -  The schematic for the SE 826 amp. This Amp was an attempt to create a nice Class A2 power amp, similar to the SE 833 amps, described below, but without a 10:1 step-down transformer. Instead, it uses a choke-loaded cathode follower to drive the output tube. It uses positive grid bias derived directly from the cathode follower driver stage. The 6F8-G driver/input tube was chosen because it biases to the required voltage (+14V) for the output stage's bias. (Note that the 6F8-G can be replaced with a 6SN7. I just happen to like the looks of the 6F8-G better) . . .  [Bob Danielok]


Class A2 SE 833 Stereo Amp -  The schematic for the SE 833A amp is shown HERE.  . . .  [Bob Danielok]


Class A2 SE 833 Stereo Amp Power Supply -  The schematic for its power supply is shown HERE. . . .  [Bob Danielok]


Class A2 SE SV572-160 Stereo Amp -  This amp uses a 6BM8 drive stage similar to the big 833A amp below, except it utilizes CATHODE drive. I presently have this amplifier set up so i can adjust the grid bias from about +2V to +30V. There is also a switch that connects the output tube grids to ground (0 Bias) instead of the grid bias supply. This way i can experiment with various output tubes, including 811A, 812A, SV572-10, SV572-30, SV811-10, etc. So far, i think the SV572-160 sounds best in this amp. I think it is because of the cathode drive (also called grounded grid) topology. I think i like the medium mu transmiting tubes, like 812A, 826, SV572-30 in grid drive amplifiers better. But in this amp, the 572-160 can be "dialed in" to a nice sweet-spot that sounds great!. . .  [Bob Danielok]


Class A2 SE826 power supply -  The schematic for the power supply. . .  [Bob Danielok]


Convertible Single Ended SV572-30/3 Stereo Amp -  This project makes use of at least two of the new SV572 series audio power triodes from Svetlana. This series includes the SV572-3 , SV572-10 , SV572-30 , and SV572-160. The circuit topology is easily re-configurable ("convertible") to use either the -30 (in Class A2 - Zero Bias operation) or -3 (in Class A1 operation). In addition, the -30 can be configured for two different drive schemes (standard grid driven configuration or Cathode Driven. A set of switches are used to reconfigure (with power off). But for clarity, the schematics are re-drawn for each mode as shown below. . .  [Bob Danielak]


Darling and DC Darling SE 1626 amps -  This has become a very popular set of amp designs. They are all based upon the 1626 Triode output tube and the philosophy to keep things SIMPLE. I am continually amazed how good these amps sound for what they are. The name "Darling" came from a good friend's description of my original design. It looked like a miniature version of "full-sized" SE 300B. The name stuck  Click  HERE  to find out more. . .  [Bob Danielak]


DC Coupled Phono Preamp -  Schematic, Only     Using 6SL7 instead, and DC-coupling of the two stages. RIAA Preamp based upon the classic RCA 12AX7 design. . . .  [from Bob Danielak's website]


Designing A Pocket Equalizer for Headphone Listening (Solid State & Tubes) -  Design principles and circuits for building opamp-based headphone amplifiers. This article reviews selection criteria, feedback configurations, capacitor coupling, RF shielding, output stage topology, short circuit protection, equalization, acoustic simulation, headphone distribution amplifiers and power supply options. AlsoDesigned by HeadWize . . . 


Direct Coupled 15 Watt Amp -  . . .  [by IQ Technologies Industry, unless otherwise noted online]


Dynakit Mark E 40 Watt Power Amplifier -  . . . 


Fender-Tone Tube Headphone Amplifier -  This tube amplifier with sonic controls has a paralleled White cathode follower output stage for driving low impedance headphones. The sonic controls consist of a Fender tone stack (bass, mid and treble) , and ambience and blend controls. Includes simulation files for use with OrCAD Lite software. . . .  [Design by Alex Cavalli ]


Get More Power With A Boosted Triode -  04/03/03  EDN Design Idea   Even though 6L6 beam-power tubes have been around for 66 years, they are still quite popular for use in electric-guitar amplifiers, and its cousin, the 6CA7 (EL34) power pentode, is a favorite among audiophiles. The developers of these tubes designed them. . .  [by Dave Cuthbert, Boise, ID ]


Hybrid vacuum tube/solid-state audio power amplifier -  08/11/14  EDN Design Idea   An audio power amp design that combines vacuum tube input circuitry with solid-state output and feedback components. Read More. . . . . .  [by Craig D. Merz]

Vacuum Tubes:  # - H        I - S       T - Z

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