Ultra Fast High Power Single Ended Amplifier
by Andrea Ciuffoli - 17 Jun 2002
The main target are:
After the experiments made with the
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
high power output: about 13W
medium power supply voltage: about 430V
very good damping factor: output resistance about 1 ohm
no feedback: only local feedback on output stage
no vacuum diodes: normal diode bridge
only 2 stages
no anodic resistors
Ultra Fast signal transfert: with the use of an SRPP (Totem Pole) and the
Tetrode in the final stage
only 8 tubes per both channels
gain enougth to be drive by any CD player
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.
All the audio transformers used in this project are
Output (price about 148$ each)
Power supply transformer (price about 117$ each)
Power supply inductance (price about 65$ each)
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
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
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
E-Z-HOOK that carries an extensive
of fine stranded and extra flexible wire.
The main schematic