Category Archives: Stereo

Bose® 901 Series I Active Equalizer #28322 Repaired

From Rain City Audio: This Bose® 901 Series I Active Equalizer #28322 came through the shop for an overhaul. The original series, these Series I Active Equalizers have the oldest electronic components which are nearly universally out of their service … Continue reading

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Bose® 901 Series II Active Equalizer #81471 Repair

From Rain City Audio: This Bose® 901 Active Equalizer, Series II #81471, just came through the shop for a repair. It’s owner sent this one all the way from Ontario, Canada for expert repair from Rain City Audio. This one … Continue reading

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Bose® Active Equalizer Test Platform

This project is going to take a while since I’m slammed in the shop, but I’m in the process of converting a Bose® 901 Series I Active Equalizer to  a test platform. With sockets for the transistors, and clip connections … Continue reading

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Bose® 901 Series II Active Equalizer #46234 Repair

This Bose® 901 Series II Active Equalizer, serial number 46234, came in for a repair just recently. As is happening with nearly all of these early ’70s equalizers by now, this one had developed poor sound quality and distortion and … Continue reading

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Neat Little 60FX5 Stereo Single-Ended Tube Amplifier

While digging around, I came across a really simple circuit in the RCA Receiving Tube Manual describing a 1WPC stereo amplifier using only two tubes, the 60FX5 power pentodes, and a single silicon diode. The 60FX5s have high enough gain … Continue reading

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The Speaker Spotter – March 3rd, 2016

Some interesting stuff on Craigslist in this week’s The Speaker Spotter, a curated selection of Seattle’s local speakers for sale online. As always, Retrovoltage is not affiliated with any of these sellers and you should click through the link to the … Continue reading

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HH Scott HHS-20 “Scotsman” Receiver Overhaul

A local repeat customer recently brought in his old HH Scott HHS-20 receiver for an overhaul. It worked a few years ago when he put it away, although not without a few issues of its own, and when he dug … Continue reading

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