{"id":1381,"date":"2010-09-17T09:19:54","date_gmt":"2010-09-17T13:19:54","guid":{"rendered":"http:\/\/www.engineeringradio.us\/blog\/?p=3928"},"modified":"2023-07-26T17:22:00","modified_gmt":"2023-07-26T21:22:00","slug":"rca-receiving-tube-manual-1964-edition","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2010\/09\/rca-receiving-tube-manual-1964-edition\/","title":{"rendered":"RCA receiving tube manual, 1964 edition"},"content":{"rendered":"
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\"RCA<\/a><\/figure>\n<\/div>\n\n\n

I found this in the great clean out of 2010, Bridgeport, Connecticut. \u00a0Once upon a time, I had a slightly newer version of this, I think from 1972 or so. \u00a0This version is from 1964 and gives a complete rundown of most small tubes that were manufactured back then.<\/p>\n\n\n\n

There is something about a well-designed, well-maintained piece of tube gear. \u00a0I remember an old Collins tube console that was in a production room at a small AM station. \u00a0The console went dead (the paper clip shorted the B+) and I fixed it.<\/p>\n\n\n\n

I recall listening to the test recording of my own voice from a reel-to-reel machine when I fixed the console. \u00a0It sounded better than I’d ever heard it, not that I have a great radio voice, by any means.<\/p>\n\n\n\n

A tube is a voltage amplifier versus a transistor, which is a current amplifier. \u00a0A tube does not have the same fidelity as a transistor, as the voltage reaches its peak, it gets a little fuzzy, adding some distortion and harmonics. \u00a0Tube gear adds warmth, what a musician might call Timbre.\u00a0The combination of fundamental frequency and varying amplitudes of harmonic frequencies allow a listener to tell the difference between a piano and a guitar playing the same note.<\/p>\n\n\n\n

This is what the current crop of tube mic preamps and other tube products tries to reproduce. \u00a0Several companies have come out with an amplifier design that has mostly transistors and one tube, usually a 12AX7. \u00a0 \u00a0Unfortunately, at least in my opinion, they fall a little short. \u00a0If you want to have the “tube sound,” it needs to be all hollow state.<\/p>\n\n\n\n

What is intriguing to me are the schematic diagrams in the back of the book.  There is one for an audio amplifier:<\/p>\n\n\n\n

\"RCA<\/a>
RCA receiving tube manual audio amp schematic diagram, C 1964<\/figcaption><\/figure>\n\n\n\n

This is a single-channel unit, for stereo, it would need to be duplicated. \u00a0Also, I would lose the tube rectifier in favor of a solid-state full wave bridge, which would simplify T2 somewhat. \u00a0The OA2 could also be changed to a diode. \u00a0Looks like unbalanced audio, which could be modified with an input transformer.<\/p>\n\n\n\n

Another interesting diagram is this one, which can be used as a mic preamp:<\/p>\n\n\n\n

\"Microphone<\/a>
Microphone Preamp schematic diagram RCA receiving tube manual C 196<\/figcaption><\/figure>\n\n\n\n

That looks like a pretty solid design, a few tweaks here or there to add some gain reduction and some type of output level adjustment and I would be a really cool piece of gear.  Again, the tube rectifier could be replaced with something solid state.  The output transformer would likely have to be changed to something like 600 ohms.<\/p>\n\n\n\n

Couple that to something like this, the Collins 26U compressor\/limiter, and one would have a great sounding microphone processor:<\/p>\n\n\n\n

\"Collins<\/a>
Collins 26U compressor limiter<\/figcaption><\/figure>\n\n\n\n

Looks pretty cool. \u00a0R10 is used to balance the two plate currents. \u00a0I would be interested in the transformer values, input\/output impedances, voltages, etc. \u00a0The 6386 tube is very hard to find these days, a good substitute would be a 5670 which is still made by several manufacturers.<\/p>\n\n\n\n

Update: \u00a0This is a picture of a Collins 26-U sitting on my boss’s floor.<\/p>\n\n\n\n

\"Collins<\/a>
Collins 26-U compressor limiter<\/figcaption><\/figure>\n\n\n\n

A great online source for tube information is Electron Tube Data Sheets.<\/a><\/p>\n\n\n\n

If I have some time this winter, it may be a fun project to fool around with.<\/p>\n","protected":false},"excerpt":{"rendered":"

I found this in the great clean out of 2010, Bridgeport, Connecticut. \u00a0Once upon a time, I had a slightly newer version of this, I think from 1972 or so. \u00a0This version is from 1964 and gives a complete rundown of most small tubes that were manufactured back then. There is something about a well-designed, … Continue reading RCA receiving tube manual, 1964 edition<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[102,4],"tags":[106,146],"class_list":["post-1381","post","type-post","status-publish","format-standard","hentry","category-audio","category-tech-stuff","tag-tube","tag-tube-gear"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/1381","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=1381"}],"version-history":[{"count":13,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/1381\/revisions"}],"predecessor-version":[{"id":12316,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/1381\/revisions\/12316"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=1381"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=1381"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=1381"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}