Category Archives: Audio

Bose® 901 Series IV Active Equalizer #509052

From Rain City Audio: This Bose® 901 Series IV Active Equalizer, #509052, was just purchased and sent to Rain City Audio for an overhaul. This unit was originally a 220V model but had already been converted to 110V on a … Continue reading

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Phase Linear 2000 Upgrade and Overhaul

From the Rain City Audio Repair Blog: I recently got to work on another Phase Linear 2000 pre-amp. These well regarded components are a fantastic part of any stereo system with their high output rating, multitude of inputs and outputs, … Continue reading

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DBX SFX-10

I saw this interesting set of speakers on Craigslist, but they sold quickly before I could investigate. They’re the DBX SFX-10s. There’s a very interesting article about their design in the May 1990 issue of The BAS Speaker, the publication … Continue reading

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Bose® 901 Series II Active Equalizer #66380 Repair

From Rain City Audio: This Bose® 901 Series II Active Equalizer #66380 came through for an overhaul just recently. The owner in California reported that he got these from his father, and the equalizer was sending only the right channel … Continue reading

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Dynaco ST-70 Stereo High Fidelity Tube Amplifier

From Rain City Audio: I recently got to work on another vintage stereo kit, the Dynaco ST-70 amplifier. These were powerful, 35W per channel stereo amps typically using a pair of 6L6GC, EL34, or similar power tubes. This turned out … Continue reading

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Bose® 901 Series IV Active Equalizer #265335 Overhaul

From Rain City Audio: This Bose® 901 Series IV Active Equalizer, #265335, just came through the shop for an overhaul. It’s owner bought this equalizer as a part of getting his Bose® system back up and running and sent it … Continue reading

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Bose® 901 Series I Active Equalizer #9724 Overhaul and Upgrade

From Rain City Audio: This rare early-production Bose® 901 Active Equalizer, serial #9724, came through the shop recently for an overhaul. It’s owner reported that both channels would cut out intermittently, the switches were noisy, and the power lamp was … Continue reading

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Bose® 901 Series IV Active Equalizer #223227 Overhaul

From Rain City Audio: This Series IV Active Equalizer, #223227, just came through for an overhaul. The owner reported it wasn’t making any sounds, just providing a DC offset on the output jacks which was giving his power amplifier some … Continue reading

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Dynaco FM-3 High Fidelity Tuner Repair

I recently got to work on a very interesting Dynaco FM tuner, the FM-3, which was in the shop for an overhaul. The owner reported it wasn’t working that well anymore, which isn’t a surprise given it’s age. These are good … Continue reading

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Bose® 901 Series I Active Equalizer #7790 Repair

From Rain City Audio: This rare early-production Bose® 901 Series I Active Equalizer, serial #7790, came through the shop recently for an upgrade. It’s original owner bought this new in 1969 and kept it in use until it began to … Continue reading

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