Tag Archives: vacuum tube hi-fi

Stereo Audio Power Amplifier (Home Use)

Posted on 01/31/2012 by chris

Above, a recently completed piece.  Built on commission for KJ.  K. selected the well-tarnished steel case from my stock; it is one of two identical NOS cabinets that I pulled from a Milford CT basement some years ago.  “Are you … Continue reading →

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The Williamson Amp, part one

Posted on 01/09/2012 by chris

The original Williamson hi-fi amplifier schematic as published in “Wireless World” magazine (UK) May 1947.   The Williamson amplifier is considered one of the earliest hi-fidelity audio amplifier designs.  It is certainly one of the most popular audio circuits ever … Continue reading →

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Mystery Amp Circa 1955: Mystery Solved. Anyone have a schematic?

Posted on 11/15/2011 by chris

I picked up a big pile of old audio equipment this past weekend; notable items included a Shure Level Loc, a massive Bogen tube pa head, a kit-built Acrosound ultralinear 5881 amp, and a Gibson acoustic gtr case from the … Continue reading →

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Sound From A Glass Box

Posted on 10/14/2011 by chris

This design project began with the goal of crafting an entire amplifier that echoed the form of a vacuum tube itself.  See here for example of the intial execution.  Thanks to cabinet-maker N.N. for the beautiful walnut frames. The 22277 … Continue reading →

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Mullard 520 Power Amplifier c.1956

Posted on 09/26/2011 by chris

Download a four-page article from “Radio & Television News” 4/1956 regarding the Mullard 520 power amp: DOWNLOAD: Mullard_520_amp American industrial titan RCA offered schematics for a variety of tube-audio equipment in the back pages of their many “receiving tube manuals.”  … Continue reading →

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1957: A Few Bits From The End Of The Mono Age

Posted on 09/22/2011 by chris

From some 1957 issues of “Radio and TV News,” an electronic-serviceman’s publication, comes this collection of American Hif-Fi home audio kit of the era.  Notice the fact that…  it’s all mono. Commercial recordings released on stereo magnetic tapes were available … Continue reading →

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Marantz 7 RIAA Phonograph Preamp

Posted on 09/12/2011 by chris

I received a commission to build a vacuum-tube phono pre-amp.  For my non-technical readers: a phono preamp is a device which does two basic things:  1) it equalizes the program that the phono cartridge picks up off the LP record, … 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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Audio Engineering Magazine Pt 4: Schematics

Posted on 05/07/2011 by chris

Today we’ll look at some of the more interesting audio-circuit plans and schematics from the first two years of Audio Engineering magazine.  Pictured above is a great lil’ amplifer (approx. 30watts) that uses a single 6AS7G tube for push-pull output. … Continue reading →

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Recent Custom-Build Stereo Amplifier (Home Use)

Posted on 04/07/2011 by chris

TR commissioned this 2x 5watt Stereo Amplifier as a gift for JK.  It is a very minimal single-ended stereo amplifier with very low gain, designed to accept headphone-level input from an iPod or Laptop and drive a pair of loudspeakers. … Continue reading →

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