Tag Archives: mic preamps

DIY Tube Broadcast Console c. 1964

Posted on 04/23/2013 by chris

From BROADCAST ENGINEERING Mag, circa 1964, plans by one Robert Tiffany on the design and construction of a low-cost ‘standby’ broadcast console.  Output amp stage uses my fav line output transformer, the UTC A-25: still unequaled among air-gapped plate:line transformers … Continue reading →

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EMI Redd 47 Mic Preamp build

Posted on 04/11/2013 by chris

So I was flipping through Recording The Beatles recently and I was reminded that I had yet to make one of those famous EMI console preamps.  As luck would have it, we were hit with a pretty major blizzard and … Continue reading →

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Audio Mixing Consoles circa 1959

Posted on 02/20/2012 by chris

Langevin stereo console circa 1959 Today: from the “Audio Cyclopedia,” Howard Tremaine, 1959: a quick visual survey of professional mixing consoles in service in 1959.  A PS Dot Com reader turned me on to the “Audio Cycolopedia”; many copies of … Continue reading →

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AWA (Amalgamated Wireless Australasia) Broadcast Equipment

Posted on 02/06/2012 by chris

Download a 24pp pdf with schematics and technical information regarding all AWA-brand vacuum-tube broadcast audio amplifiers circa 1967: DOWNLOAD: ABCstudioEquipment Big thanks to PS dot com reader E. Lorden.  E. lives in Australia and has provided us with extensive schematics … Continue reading →

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The BRDCSTR

Posted on 12/15/2011 by chris

Above: The BRDCSTR, a two-stage vacuum-tube microphone preamp inspired by classic 1940s broadcast audio preamps.  Single-ended design with a 6SJ7 and 6J7 tubes, massive output transformer, and only one capacitor in the signal path.  I have built more of these … Continue reading →

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The Old ’76

Posted on 11/22/2011 by chris

My latest microphone preamp design is completed and sounding very cool… The Old ’76. The Old ’76 is a novel three-stage design; it’s not based on any past or current production microphone preamp.  That being said, the circuit is nothing … Continue reading →

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UDPATED (3): Presto Recording Corp: Pioneers of ‘Instant’ Analog Disc Recording

Posted on 09/13/2011 by chris

Download the fifty-page 1940 PRESTO RECORDING CORP catalog: DOWNLOAD (part 1): Presto_1940_Cat_1 DOWNLOAD (part 2):Presto_1940_cat_2 Products covered, with text, some specs, and photos, include: Presto Model A, Model B, Model F recording installations; Presto Model C, Model Y, and Model … Continue reading →

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RCA OP-6/BA-2 Hybrid Mic Pre Amp: Listening Test/Shootout

Posted on 06/04/2011 by chris

Alright!  So earlier this week I described the successful completion of the RCA OP-6/BA-2 microphone preamp.  Check out this previous post for all the construction and technical details.   The short story is: the RCA OP-6 is one of the … Continue reading →

Posted in Custom Fabrication, Gold Coast Recorders, Technical | Tagged , , , , | 2 Comments

Building an (almost) RCA OP6 Mic Preamp

Posted on 05/31/2011 by chris

(image source) The RCA OP-6 ‘Portable Amplifier’ is one of a handful of truly visually-iconic vintage mic preamps.   The OP-6 was designed as a “remote,” as-in, ‘on-location’ single-channel mic preamp for radio station broadcasts.  It uses three 1620 (6J7) tubes  … Continue reading →

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A Few Interesting DIY Audio Projects c. 1955

Posted on 05/28/2011 by chris

Circuit for a simple bass/treble parametric equalizer that uses no inductors.  Could be  a useful piece.  Not sure if 250k/500k dual pots are still available?  Since I have still not finished building the last tube EQ project that I described, … Continue reading →

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