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Author Archives: retrovoltage
Upcoming Projects – Q4 2026
I’m working on a few projects right now, and hope to have several of them fixed up and ready to post before the end of the year. Likely a few more ad-hoc, too. KLH Model 20 set with speakers and … Continue reading
Posted in Electronics
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The Speaker Spotter — October 2, 2026
A recurring feature curating interesting speakers for sale on Craigslist from around the Pacific Northwest. Links to Craigslist postings might go down at any time if they’re sold or pulled from sale. 1977 Klipsch La Scala $3,500 · Portland Someone’s … Continue reading
The Speaker Spotter — September 26, 2026
After a short hiatus while I sorted out some tech issues with automation that helps me create these posts, we’re back! The Speaker Spotter is a recurring feature curating interesting speakers for sale on Craigslist from around the Pacific Northwest. … Continue reading
Posted in Audio, Electronics, Speakers
Tagged audio, music, Speakers, Technology, vintage
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New Bench Gear: September 2026
A few new pieces of gear join the bench in September 2026: an HP 53181A frequency counter, and a Tektronix 434 Storage Oscilloscope. Continue reading
Posted in Electronics, Gadgets, Test Equipment
Tagged Flea Market, hp 53181a, tektronix 434, test equipment
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The Speaker Spotter — August 14, 2026
A recurring feature curating interesting speakers for sale on Craigslist from around the Pacific Northwest. Links to Craigslist postings might go down at any time if they’re sold or pulled from sale. Some really interesting, highly unusual things in today’s … Continue reading
Posted in Audio, Electronics, Speakers, Stereo, Vintage
Tagged audio, Cerwin Vega, hifi, jbl, KLH, Klipsch, Speakers, vintage
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Everything to Know about the Bose 901 Series IV Speakers & Active Equalizer Repair
A detailed look at the Bose 901 Series IV speaker system and Active Equalizer, with a brief history and explanation, plus repair tips and tricks, schematics, a discussion of the 5 different Active Equalizer versions for this generation, and a parts list with direct links to buy. Continue reading
Posted in Audio, Bose, DIY, Electronics, Hi-Fi, Stereo, Vintage
Tagged 901, audiophile, Bose, Bose 901, electronics, Equalizer, repair, restoration, series IV, stereo, Technology, vintage
3 Comments
The Speaker Spotter — August 7, 2026
A recurring feature curating interesting speakers for sale on Craigslist from around the Pacific Northwest. Links to Craigslist postings might go down at any time if they’re sold or pulled from sale. Slightly fewer in today’s roundup than usual, but … Continue reading
Posted in Electronics
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Everything to Know about the Bose 901 Series III Speakers & Active Equalizer Repair
A look at the Bose 901 Series III speaker system and Active Equalizer, with a brief history and explanation, plus repair tips and tricks, schematics, and parts list with direct links to buy. Continue reading
Posted in Bose, Electronics, Hi-Fi, Stereo, Vintage
Tagged Active Equalizer, audio, audiophile, Bose, Bose 901, electronics, Equalizer, repair, restoration, series 3, series III, stereo, Technology, vintage
4 Comments
The Speaker Spotter — July 31, 2026
A recurring feature curating interesting speakers for sale on Craigslist from around the Pacific Northwest. Links to Craigslist postings might go down at any time if they’re sold or pulled from sale. klipsch la scala industrial split $2,300 · Eugene … Continue reading
Posted in Audio, Electronics
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1961 Audax CA-70 “Sonoteer” Speaker Refurbish
This set of 1961 Rek-o-Kut Audax CA-70 Sonoteer speakers got a full overhaul inside and out. Come learn about these interesting mid-century open baffle hi-fi speakers from a little known manufacturer and see how they turned out with detailed interior and exterior photos, and the original advertisement from September 1961. Continue reading
Posted in Audio, Hi-Fi, Projects, Speakers, Stereo, Vintage
Tagged audax, ca-70, mid-century, restoration, sonoteer, speaker repair, Speakers, upgrade, vintage speaker
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