Selected documents from the Retrovox Archives scanned at 300 dpi from the original hard copy documents. No copyright is implied or assumed. Adobe Acrobat Reader required to view PDFs. Screen shots are gif images, lower resolution than Acrobat files.
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PROFESSIONAL TRANSMISSION, BROADCAST and STUDIO EQUIPMENT
A.B.C. Studio Sound Equipment. Australian Broadcast Commission Training Publication with diagrams of early pre-amps and line amps used by the ABC and PMG. There is a useful table which shows where in the reproduction chain and at what typical levels each type of amp was used, along with input and output impedances. 27 pages PDF download 1.5MB
Trimax A30 Limiting Amplifier. Full handbook with parts lists and circuit diagrams, plus detailed explanation of circuit function. Uses one 6J7, four 6SN7GT, two 6SJ7GT, one 6X5GT and one 0D3. Published by Trimax Transformers Melbourne Australia, late 1940s. 11 pages PDF download 1.4MB
Type 2 Amplifier. The Type 2 Amplifier was used as an isolating and bridging amplifier. Uses two EL91 / 6AM5 pentodes. Operating Handbook published by Centre Industries, North Manly, NSW. January 1965. 4 pages PDF download 210KB Screen shots (gif) Specifications Parts list Circuit diagram
Type 3 Amplifier. The Type 3 Amplifier is a power amp using one 6AU6, one 12AT7 and two EL34 valves. Operating Handbook published by Centre Industries, North Manly, NSW. January 1965. 5 pages PDF download 260KB Screen shots (gif) Specifications Parts list Circuit diagram
Westrex RA-1593A compressor and RA-1594A control unit. USA made vari-mu type compressor. The variable gain stage uses 12BA6 valves. Variable attack, release, compression ratio, threshold and de-essing. These circuit diagrams are from Tremaine's Audio Cyclopedia. 2 pages PDF download 250KB Screen shots (gif) 1593A 1594A
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