Category Archives: Audio

Bose® Active Equalizer Test Platform

Posted on April 13, 2016 by retrovoltage

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 retrovoltage

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 retrovoltage

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 retrovoltage

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 retrovoltage

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

Philips High Fidelity Laboratories 673 Tuner Repair and Alignment

Posted on January 4, 2016 by retrovoltage

This Philips 673 tuner just came through the shop for an overhaul and adjustment. It was working for the most part but the alignment had shifted and there was room for improvement on the sound quality. Philips designed this tuner … Continue reading →

Posted in Audio, Electronics, Radio, Vintage | Tagged , , , | 3 Comments

HH Scott 233 Stereo Integrated Amplifier Overhaul

Posted on December 31, 2015 by retrovoltage

I was lucky enough to get to work on a very nice Scott 233 stereo integrated amplifier. This example was wonderfully well preserved, coming out of a storage unit looking like it had just left the showroom floor. Unfortunately, though, … Continue reading →

Posted in Audio, Electronics, Radios and Tubes, Stereo, Vintage | Tagged , , , , , , | 7 Comments

What do we have here?

Posted on December 1, 2015 by retrovoltage

I was reading about how to build a capacitor checker from the December 1959 issue of Popular Electronics and stumbled across something that looked very familiar. I know that shape. Nearly identical to a Bose® 901 Series I/II cabinet, and even … Continue reading →

Posted in Audio, Bose, Collections, Commentary, DIY, Electronics, Vintage | Tagged , , , , , , , , , , , , , | 2 Comments

Bose® 402E Active Equalizer #102853 Repaired

Posted on November 30, 2015 by retrovoltage

The first Bose® 402E Active Equalizer, for the Panaray speaker system, just came through the shop. It’s a small speaker array system, designed around similar drivers in the 901, and uses an Active Equalizer for the same effect. They’re designed … Continue reading →

Posted in Audio, Bose, Electronics, Projects | Tagged , , , , , , , , | 7 Comments

Harman-Kardon Festival D-1000 Tube Receiver Repair

Posted on November 17, 2015 by retrovoltage

All vintage gear has a story to tell, but something really rare and interesting recently came across the bench: the Harman-Kardon Festival D-1000. While it looks somewhat unassuming, a fairly straightforward 15-tube receiver with push-pull 6L6GC outputs and an AM … Continue reading →

Posted in Audio, Electronics, Hi-Fi, Vintage | Tagged , , , | 4 Comments