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Ultra Fast High Power Single Ended Amplifier

by Andrea Ciuffoli - 17 Jun 2002

Introduction

The main target are: After the experiments made with the
20W Push Pull converting this many times from a push pull to a single ended only connecting a grid of an output tube to ground (instead of the interstage transformer) the result has been always the more superiority of the Single Ended sound because the sound is more natural and any instrument is more true.
The my idea was to create a project with the same normal and low cost output tubes with enougth output power to drive normal loudspeakers (with an efficiency about 88-89db) and without high power supply voltage.
So a project for beginner but high performance at low cost.



Components

All the audio transformers used in this project are Lundahl products:

Lundahl is one of the world´s leading manufacturer of audio transformers used in many professional studio recording and radio stations so He have a very big experince and all these products use a custom audio C-core.

The driver stage are two 12AX7/ECC83 Mullard or Jan Philips

The output tubes used are the new Svetlana KT88.

but I have tested with this circuit  output tubes like the  KT90 EI.

About passive components types,  I don't leave many choices:  Holco or Caddock resistances on cathode, ELNA Cerafine capacitors on cathode and power supply.
For all my new projects, I am using the very good ELNA Cerafine capacitors that I love and which can be find at good price by
AUDIOKIT.
The ELNA Cerafine capacitors contain super fine ceramic particles which, through chemical reaction, improve the discharging speed between the anode and electrolyte with very low distortion.
Any other electrolytic or polypropylene capacitor give very lower sonic performances introducing some alteration. Only the Blackgate WKZ could give better sound, but I have not tested it and I know of some problems during startup phase.

About wire forget the teflon ! use only stranded tinned copper wire with pvc isulator and for loudspeakers I am testing the elevator cables (paralleled wire with a good section).

A very good quality stranded tinned copper wire could be buy directly from E-Z-HOOK that carries an extensive line of fine stranded and extra flexible wire.



The main schematic