Category Archives: Audio

Sherwood S2000-III Tube FM Tuner Repair

Posted on January 8, 2015 by retrovoltage

Sherwood made some excellent hi-fi FM tuners back in the day, and this S2000-III is no exception. Unfortunately, there’s not a lot of documentation about this model available, but that didn’t stop it from getting an overhaul and alignment. The … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Radio, Radios and Tubes, Vintage | Tagged , , , , | 1 Comment

Harman-Kardon Citation 17S Pre-Amplifier Refurbishing

Posted on January 2, 2015 by retrovoltage

I recently got to work on a Harman-Kardon Citation 17S pre-amplifier. Vintage HK gear is some of my favorite to work on: it’s robust, reliable, and built to be easy to service. The Citation 17 pre-amplifier is the companion for … Continue reading →

Posted in Audio, Projects, Stereo, Vintage | Tagged , , , , , , , , | 1 Comment

Watch a McIntosh Tube Amp Come to Life

Posted on December 27, 2014 by retrovoltage

Discovery’s How It’s Made shows us how a McIntosh vacuum tube audio amplifier comes to life: http://www.youtube.com/watch?v=2HgS6gvokEI Definitely worth watching!

Posted in Audio, Commentary, Hi-Fi, Radios and Tubes, Stereo | Tagged , , , , , | Leave a comment

Sony TA-5650 VFET Integrated Stereo Amplifier Overhaul

Posted on December 18, 2014 by retrovoltage

I recently got to work on a very interesting piece of vintage stereo gear from the golden age of hi-fi in the ’70s, the Sony TA-5650 VFET Integrated Stereo Amplifier. It’s a little rough, and while the power amp section … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Projects, Vintage | Tagged , , , , , , , , , | 1 Comment

How Speakers Make Sound

Posted on December 3, 2014 by retrovoltage

If you’re looking for a great visual primer on how speakers convert electricity into the music you hear, check out this fantastic animated infographic by Jacob O’Neil at Animagraffs  How Speakers Make Sound

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Boxed Kit Amps’ Gobo Stereo Amplifier Build and Review

Posted on November 26, 2014 by retrovoltage

If you’re a subscriber to Nuts and Volts Magazine, check out my article in the December 2014 issue where I build, test and review the Boxed Kit Amps Gobo Stereo Amplifier, a great little desktop reference amp for any skill … Continue reading →

Posted in Audio, Commentary, DIY, Electronics, Gadgets, Hi-Fi, Projects, Stereo | Tagged , , , | 2 Comments

VD-1221 Replacement Substitute Diodes

Posted on November 25, 2014 by retrovoltage

VD-1221, VD-1212, VD-1220, VD-1222, and many other vintage multi-junction diodes probe to failure, which are used in bias and RF mixer circuits, can be easily replaced by series combinations of 1N4148 diodes for reliability and longevity. Continue reading →

Posted in Audio, DIY, Electronics, Vintage | Tagged , , , , , , , , , , , , , , , , , , | 8 Comments

Harman/Kardon Control Amplifier A-401 Restoration

Posted on November 19, 2014 by retrovoltage

This little Harman/Kardon Control Amplifier, model A-401, just came through the shop for a full overhaul. It was in a pretty sorry state to begin with – one channel distorted, one barely gasping for air, and a world of scratchy … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , , , | 8 Comments

EICO Stereophonic Integrated Amplifier HF-81 Repair

Posted on November 7, 2014 by retrovoltage

From the late ’50s, I had this nice example of an EICO HF-81 amplifier come through my shop. These are nice little stereo amplifiers with a built-in phono pre-amp and RIAA equalization and feature about 14W of power output per … Continue reading →

Posted in Audio, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , , | 1 Comment

Boes 901 Series IV Active Equalizer #241792 Refurbishment

Posted on November 3, 2014 by retrovoltage

Bose® 901 Series IV Active Equalizers are getting up there in years now, too, so more and more are coming up for repair. This one came in with a flickering power supply in need of an overhaul. Series IV was … Continue reading →

Posted in Audio, Bose, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , | 1 Comment