Category Archives: Audio

HH Scott HHS-20 “Scotsman” Receiver Overhaul

Posted on January 27, 2017 by jwk

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 →

Posted in Audio, Electronics, Projects, Stereo, Vintage | 3 Comments

Music Minder Automatic Power Controller for Hi-Fi Systems

Posted on August 24, 2016 by jwk

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 →

Posted in Audio, Electronics, Gadgets, Hi-Fi, Vintage | Tagged , , , , , | Leave a comment

Reviewing the Gemtune APPJ PA1501A 6AD10 Stereo Tube Amplifier

Posted on August 17, 2016 by jwk

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 , , , , , , | 15 Comments

DBX SFX-10

Posted on May 31, 2016 by jwk

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 →

Posted in Audio, Electronics | 5 Comments

Bose® Active Equalizer Test Platform

Posted on April 13, 2016 by jwk

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 →

Posted in Audio, Bose, DIY, Electronics, Stereo, Test Equipment | Tagged , , , , , | 3 Comments

“Won’t that ruin the vintage sound?”

Posted on March 16, 2016 by jwk

Audio as a hobby sits in an interesting place in the world. There are hard numbers and objective measurements made with lab equipment on one end, and on the other end you have the subjective and variable linguistic descriptions assigned … Continue reading →

Posted in Audio, Commentary, Electronics, Hi-Fi, Vintage | Tagged , , , , , , , | 3 Comments

Neat Little 60FX5 Stereo Single-Ended Tube Amplifier

Posted on March 6, 2016 by jwk

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 →

Posted in Audio, DIY, Projects, Stereo | Tagged , , , , , | 5 Comments

The Speaker Spotter – March 3rd, 2016

Posted on March 3, 2016 by jwk

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 →

Posted in Audio, Collections, Speakers, Stereo | Tagged , , , , , , , , , | Leave a comment

The Speaker Spotter – February 14th, 2016

Posted on February 14, 2016 by jwk

Another installment of the occasional series “The Speaker Spotter”, showcasing interesting speakers for sale right now on the local Seattle Craigslist. As always, I am not affiliated with any of these postings. If the linked ad doesn’t load, it’s likely … Continue reading →

Posted in Audio, Collections, Speakers | Tagged , , , | 3 Comments

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

Posted on January 20, 2016 by jwk

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 →

Posted in Audio, Bose, Electronics, Projects | Tagged , , , | 1 Comment