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 — Schematic Circuit Diagrams —

The following is a list of Valve equipment and some classic transistor schematic diagrams.

To increase clarity and or reduce the file sizes some have been traced, redrawn and output in Adobe Acrobat pdf format.

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Where possible I have redrawn the following schematics in the original style and layout so there may be a few inaccuracies, please let me know and I will correct them — Where components are concerned I have generally used common symbols for basic parts i.e. an electrolytic capacitor is drawn in the old British style and looks like where the shaded end is negative — The American symbol would be where the curved side is negative

I have elected to use the british symbol for redrawn schematics — Resistors are drawn which is common to nearly all older schematics and looks like a difficult path for current or even a heating element which is actually what it is! — The box symbol indicates nothing but I use it for the day job and some schematics that I produced for this site

Another area to look out for is junctions, most older schematics use bridges to show wires that cross later becoming a simple cross + — Junctions are often marked with dots — As a rule however drawn no more than 3 wires should meet at a junction — I have elected to use bridges or simple crosses with junction dots (often coloured differently) and more than 3 wires at junctions if it reflects the original style and is obvious what is connected

Schematic Source
File Size
AcroSound 6L6 Rebuild DCD customer re-build drawing as supplied with repaired amp
33kB
Ultra-Linear Amplifier Hafler and Keroes from Audio Engineering 1951 — Searchable and scaleable pdf — Also see Original Article
172kB
High Quality Amplifier 1947 Wireless World Article by D.T.N. Williamson
57kB
High Quality Amplifier 1949 Wireless World Article New Version by D.T.N. Williamson
66kB
QUAD II Power Amplifier From the QUAD II handbook redrawn in the original style
49kB
QUAD II Power Amplifier Relaid for PSPICE Analysis gives a different perspective
33kB
QUAD "Concordant" Mod Traced from a "Concordant" modified QUAD II
80kB
Quad AM II Tuner Scan from drawing supplied with original handbook
80kB
Quad 22 Control amplifier Redrawn on A4 but as scaleable and searchable pdf file
300kB
QUAD405 Evolution A Compilation of redrawn QUAD 405 circuit diagrams covering all production versions plus some Keith Snook DCD mods
280kB
QUAD 405 Service Data pdf version of the original QUAD 405 and 405-2 service data
2MB
QUAD 405 input stage mod DCD 405 Article
27kB
QUAD 606 service data Scanned QUAD 606 schematic
800kB
QUAD FM4 pdf of scan (A3 size) for s/n 11,000 onward
172kB
QUAD 34 Pre-amplifier Redrawn —To support my QUAD 34 Mods
196k
QUAD34 Moving Coil Disc input modules modifications From DCD QUAD 34 Mods
24kB
11Ω BBC LS3/5A modified DCD Speakers LS3/5A external crossover modification
92kB
11Ω BBC LS3/5A Standard DCD Speakers — Standard 11Ω model diagram
83kB
SAI guitar amp Passive tone control modification for this "Marshall" copy amp
37kB
Note: This information is offered for free and without warranty — All files carry either a watermark or a unique identifier — If you intend to use this information for commercial use certain laws may apply in some parts of the world — Otherwise share and enjoy — And please be careful not to electrocute yourself

QUAD Hi Fi Quad Modifications and information Valve data Sheets Component Colour Codes QUAD Hi-Fi Buy Beer Button

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