Author Archives: jwk

Oops…no posts!

It looks like my automatic re-post script which posts things from the shop blog over to Retrovoltage hasn’t been working for a bit. Sorry for the lack of posts! I’ve been up to quite a few projects recently, so look … Continue reading

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Music Minder Automatic Power Controller for Hi-Fi Systems

Mixed in with some other gear I’m servicing, I found this old Music Minder power box. It’s not all that obvious what it’s for at first glance! Some digging around found an explanation in the June 1958 issue of Popular … Continue reading

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Reviewing the Gemtune APPJ PA1501A 6AD10 Stereo Tube Amplifier

I recently picked up an interesting little tube amp via a group buy on Massdrop, the Gemtune APPJ PA1501A stereo tube amplifier. Try saying that three times fast! It’s a cute little single-ended stereo tube amp using a pair of 6AD10 … Continue reading

Posted in Audio, Commentary, Electronics, Hi-Fi, Stereo, Toys | Tagged , , , , , , | 13 Comments

Fisher 400 Wide-Band FM Multiplex Receiver Overhaul

From Rain City Audio: The Fisher 400 is a very well engineered, and very collectible, vintage stereo receiver with an iconic champagne faceplate and prominent bank of controls. This one came through the shop after being stored in a garage … Continue reading

Posted in Audio, Electronics, Projects, Radios and Tubes, Vintage | Tagged , , | 4 Comments

Bose® 901 Series VI #181070 Repair

From Rain City Audio: This Bose® 901 Active Equalizer, Series VI, came into the shop recently. These are some of the most recently produced Active Equalizers, although they’re still potentially a few decades old at this point in time. This … Continue reading

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Would you look at that!

It’s pretty, but this 12BA6 tube has amplified for the last time. Vacuum failure has led to a gas intruding into the vacuum, and it makes a great light show when it’s being tested! As cool as it looks, this would cause … Continue reading

Posted in Photos, Radios and Tubes, Vintage | Tagged , , , | 1 Comment

Bose® 901 Series II #65097 Overhaul

This Bose® 901 Series II Active Equalizer, #65097, just came through the shop for an overhaul. It worked briefly, but failed quickly on its original components. Nothing that an overhaul can’t take care of! This particular unit had its three … Continue reading

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