Tag Archives: Active Equalizer

Bose® 901 Series II Active Equalizer #64364 Overhaul

This Series II Bose® Active Equalizer came through the shop. It had suffered age-related failures in its electrolytic capacitors, and the resistors had drifted with age and moisture to produce the wrong curves. Fortunately, it’s nothing some maintenance can’t solve! … Continue reading

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Bose® 901 Series I Active Equalizer #6878 Repair

This early-production Bose® 901 Active Equalizer came through the shop recently for a repair. These Early models were the very first production run, back in 1968, and have a pretty significantly different circuit design from the later models, and feature … Continue reading

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Bose® 901 Series IV Active Equalizer #253288 Overhaul

This Bose® 901 Series IV Active Equalizer came through the shop for a full overhaul. Inevitably over the years, various parts wear out and degrade and can make the equalizer sound bad – or not work at all. Without the … Continue reading

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Bose® 901 Series IV Active Equalizer #501554 Overhaul and Upgrade

From the Rain City Audio Repair Blog: This Bose® 901 Series IV Active Equalizer, serial #501554, came into the shop with the owner reporting that it loses output on one channel and the sound degrades the longer it is powered … Continue reading

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Bose® 901 Series IV Active Equalizer #219533 Overhaul

From the Rain City Audio Repair Blog: This Bose® 901 Series IV Active Equalizer, serial #219533, came through the shop for an overhaul. The owner was reporting the left channel went out, so it’s clearly time for an overhaul! A … Continue reading

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Bose® 901 Series IV Active Equalizer #269557 Repaired

From the Rain City Audio Repair Blog: Another Bose® 901 Series IV Active Equalizer came in through the shop for an overhaul recently. This one was a bit unusual, and represents a fairly significant deviation from the published service manual. … Continue reading

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Bose® 901 Series IV Active Equalizer #221114 Repaired

From the Rain City Audio Repair Blog: Another Bose® 901 Series IV Active Equalizer came through the shop, this one serial #221114. It’s owner reported that it had lost one channel, so it was clearly due for an overhaul. It … Continue reading

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Bose® 402E Active Equalizer #102853 Repaired

From the Rain City Audio Repair Blog: The first Bose® 402E Active Equalizer, for the Panaray speaker system, just came through the Rain City Audio repair bench. It’s a small speaker array system, designed around similar drivers in the 901, … Continue reading

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Bose® 901 Series I Active Equalizer #51616 Repaired

From the Rain City Audio Repair Blog: Another Bose® 901 Series I Active Equalizer came through the shop for an overhaul! This one was from the very end of the Series I production run, serial #51616. This one appeared to … Continue reading

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Bose® 901 Series II #101043 Repaired

Cross-posted from the Rain City Audio repair blog: Another Bose® 901 Series II Active Equalizer came into the shop recently for a full overhaul. These equalizers are getting pretty old and even if they power up and pass some sound, … Continue reading

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