Dynaco Push-Pull EL84 / 6BQ5 or 6V6 / 6AQ5 Tube Amp Schematic
![6aq5 push pull amplifier 6aq5 push pull amplifier](/uploads/1/2/5/8/125839541/889077942.jpg)
The EL84 (6BQ5) / 6V6 Push-Pull tube amplifier schematic and text below is from the Dynaco Super-Fidelity Output Transformers catalog circulated around 1955.
6AQ5W/6005 UL Single-Ended 4Ch Power Amplifier with Hashimoto Transformers. This amplifier was originally featured on the January 2004 Issue of the 'High-Fidelity Audio: Radio Technology' by Mr. Tadaatsu Atarashi. Atarashi designed this amplifier for the multi-channel SACD application with just four-channels instead of the normal five. 2019- Push-Pull (PP) EL84 (6BQ5) or 6V6 (6AQ5) Tube Amp Schematic with Dynaco A-410 Transformers.
'Figure 3 illustrates a low power circuit (12 watts at less than 1% distortion) which is similar to that used in many of the medium priced commercial amplifiers. Either EL84/6BQ5 or tubes of the 6V6 and 6AQ5 type can be used in this configuration with the Dynaco A-410 transformer (8000 ohms CT). The use of this super-fidelity transformer in commercial grade equipment makes a substantial improvement in transient response as well as drastically lowering the distortion. Most commercial amplifiers can be greatly improved merely by direct substitution of the Dynaco A-410 for amplifiers of the 6V6 type.'
Push-Pull (PP) EL84 (6BQ5) or 6V6 (6AQ5) Tube Amp Schematic with Dynaco A-410 Transformers
The power supply uses a 5Y3 tube rectifier and a C-R-C filter. More information about tube power suppies is available in the Power Supply Design for Vacuum Tube Amplifiers article.
For an application of this push-pull tube amplifier schematic using 6SL7 and 6V6 tubes, see Brad's 6SL7 driver, 6V6 push-pull DIY tube amplifier build.
The main test device I don't happen to have is a Signal Tracer. Recently, I found a circa 1960's home built project that can easily become the main part of a Signal Tracer. The circuit is almost identical to this:From 'Fun with Tubes'. My job with this one includes replacing the caps, which all look bad, and basically bringing it up to modern safety standards. For example, the original builder used an ordinary 2 conductor lamp cord with an non polarized plug, and no fuse. The metal case that the project was built into als serves as the circuit ground. So, the wire that runs from the negative side of the first 40 uf capacitor to the ground side of input to the 6AQ5 tube is the metal case itself. Finally, there is no bleeder resistor across the output of the high voltage circuit. So, once I've added the additional wire and bleeder resistor, along with possibly adding a 3 conductor power cord, the unit will be safer to use. Also, I think the original builder may have used some parts that they had on hand. There is a 470 ohm cathode resistor on the 6AQ5. That's a bit high for a beam power tube, don't you think? Another item is that a 5 pin battery connector was used for the power output and amplifier input. The high voltage ground and amplifier input ground shares a common pin. I'm hoping there turns out to be enough room in there to install an octal plug. I have a cable with octal plugs on each end that was once used to connect a McIntosh C8 preamp to a power amp. I'd like to use this since it would still keep the project largely period correct. Once this is up and running, all I'll have to add is a little two triode or double triode preamp, powered by this project, to make a signal tracer....