Hello everyone, my name is Patrick Turner. In 2012 I retired and closed my
business located in Canberra, Australia.

Most recent update to the site 22 July 2014.

I no longer offer repair services to any new customers.
I have several amplifier projects underway which I may get done by 2047.
I may advertize some tube amps for sale during the next few years.

This website now exists to provide much information about domestic hi-fi audio systems using
vacuum tubes and limited use of solid state. The site provides answers to most questions to enable
DIYers to build their own sound systems.
DIYers NEED to understand the basic theory about vacuum tubes
and all other
basics of electronics as described in many books on electronics written before 1965.

My address is in the .gif image so type this into your email program.
Telephone...(02) 6241 2760.......10am to 7pm
I do NOT own a mobile phone, I am NOT at Facebook, or Twitter, and don't have Skype.

Recently updated pages are :-

About health matters. Any intelligent polite comments are welcomed from anyone anywhere.

My interest in cycling and health explained.

Recently added or re-edited web pages include :-
Mr Zel's 100+100 integrated amp 2014. About 2 channel PP amp with 25% CFB in OPT, fixed bias,
bootstrapping, and several schematic options for input driver stages, detailed protection and LED bias setting.
Reformed Quad-II monobloc amps, 2014. Much more useful information about Quad-II.
Reformed Dynaco MkIV monobloc amps, 2014. Getting better performance from 1960 Dynaco amps.
Reformed Dynaco ST70. This page on famous ST70 has been re-furbished to be a better guide to all.
Reformed Quad-II-Forty monobloc amps. Getting better performance from Quad-II-Forty, 2011.
PP amp Output Stage Configurations 2014. Unusual series output tubes and use of PP
UL OPTs for CFB.
100W UL AB1 monobloc amp 2014. Four more schematics and balanced biasing.
100W UL AB1 monobloc amp 2004. Tided up old page.
SE Amp Output Stages. Basic and challenging SE tube amp output stages.
PSU for testing tubes. A schematic of my bench top PSU for testing tube performance.
OTL amps, about 6AS7, 6C33c.  All about the bad in OTL amps, and very little good,
and how to use 6AS7 and 6C33c with OPTs.
Wien Bridge Oscillators with tubes. 1Hz to 2MHz, 4 pentodes,
with improved mosfet Schmitt trigger for square waves.
Wien Bridge Oscillator. 1Hz to 1MHz sine and square waves, discrete bjts+j-fet amp
Reformed 30W RCA amps. About re-engineering of these classic monoblocs.
Tube Operation 5. About use of Differential Amp stages for PP amp inputs.
Speaker Matching Transformers. About using better impedance matching for amps.
Loudspeakers 5. About handcrafted bamboo ply boxes with NOS Tannoy drivers.
Solid state 5. About hybrid amps using tube input/drivers, mosfet outputs.

THD measurement.  About the gear needed for THD testing of amplifiers.

From 1996 to 2012, I manufactured a range of amplifiers and re-engineered many others,
and I made loudspeakers.......

POWER AMPLIFIERS.  Many pages about tube amplifiers, 4Watts to 300Watts.
ALSO 5 pages on solid state amplifiers including latest page on hybrid class A amps
with class A mosfets driven with vacuum tube input stages.

1 page on chassis and metal work for possible future amps.

PRE-AMPLIFIERS.   4  pages for tube line level and phono preamps.

LOUDSPEAKERS.   Several educational pages about full range premium quality
stereo loudspeakers and pages about DIY speakers and testing speaker performances.

RE-ENGINEERED AMPLIFIERS.   5 Pages on what might be done with old amps
such as Quad, Leak, Dynaco ST70, Dynaco MkIV, JBL amps, Jadis SET, RCA 30W,
all done to make them sing to meet 2014 expectations, and stop smoke production.

RADIO RE-ENGINEERING.  About re-engineered AM radios.

OUTPUT TRANSFORMERS FOR SALE. 58 types of OPTs for diyers and others.
OUTPUT TRANSFORMER INFORMATION.  About OPT for sale, use, choice.
for sale. 
POWER TRANSFORMERS FOR SALE. 103 types power trans for diyers or others.
POWER TRANSFORMER INFORMATION.  Properties of PT, choice, conditions of sale.
CHOKES FOR SALE.  A page with some new and old chokes for sale.
MISCELLANEOUS FOR SALE.  A small number Junk Items. 
Updated June 2012. I have a few old solid state amps, all need repairs.

SOME TUBES FOR SALE. I have small stocks of Russian output tubes and input tubes
for amps and some old tubes for AM radios.

General domestic hi-fi experience and very basic technical issues,1 page.
Tube operation, basic and complex, 5 pages.
Output stage configurations, 1 page.
Load Matching of SE and PP output tubes,
4 pages.
Output Transformer theory, design, calculations, examples of OPTs, winding, 11 pages.
Speaker Matching Transformers,1 page.
OTL amps, and alternatives, 1 page.
Power Supplies for tube amps,
1 page.
Power Transformers and Chokes,
1 page.
Chokes for CLC filters, Choke Inputs, and anode DC feed, 3 pages.
AM-FM tuner, tubed,1 page.
THD measurement, 1 page.
Amplifier frequency response testing, 1 page.
Wien Bridge oscillators with solid state or tubes plus Schmitt Triggers,
2 pages.
PSU for testing tubes with variable regulated B+ from +126Vdc to +585Vdc, 1page
Miscellaneous Schematics, power amps, preamps and other items,
2 pages.

Mr Zel's Cobra stereo amp with 6DJ8, 6BL7 and 4 x EL34 per channel.  

REPAIRS  after August 2012, I will not accept any new customers, but will service gear
purchased from me or re-engineered before August 2012.
I will not touch old customers new acquisitions of amplifiers.
Exceptions to this rule are possible if anyone wanting anything is willing to pay $80
per hour tradesman's rates for each and every hour spent including any computer time,
plus any costs for parts or material. Over last 20 years, Everyone expected that I fix
their old 1960 amps for old 1960 wage rates.