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Dynaco Stereo 80 Power Amplifier

outside view showing replaced audio i/o connectors

About the Stereo 80

The Stereo 80 was the little brother of the Stereo 120. The Stereo 80 and 120 had similar designs. The main differences were:

The 120's regulated supply maintains the power supply output at 72 volts until the current limit is reached. The 80's unregulated power supply output voltage sags as output power increases. Owing to the regulated power supply, it's my belief that the 120 should measure and sound better than the 80, but there are a wide variety of opinions on this subject.

Here's a scan of the service/user manual from my collection, Stereo 80 Manual (9 Meg Download pdf).

Stereo 80 Replacement Components

Here are the Stereo 80 replacement components available at this time:

Restoring a Stereo 80 with the PWRAMP80 Kit

This gallery shows how I started with a particularly dirty Stereo 80, and ended up with a nice sounding amp. At the end of the day, there are still some cosmetic problems. The Mother's Chrome polish did a good job, but the chrome part of the chassis was so heavily pitted that a lot of rust damage remains. Still, the amp sounds and measures great! Then too, it only cost $40 on Ebay!


Stereo 80 Capacitor Kit

The most usual failure mode in the stereo 80 is that the big can capacitors lose capacitance. We listed them above, but there's an easier way to go. Just order the Stereo 80 Capacitor Kit. It bundles the following items:

Updated Stereo 80, the Hard way!

outside view showing replaced audio i/o connectors

Long before the PWRAMP80 kit was available, one of my customers, Tim, did the first such conversion. For that conversion, he ordered:

Tim is a handy guy, and he fabricated his own version of super heatsinks, along with a special super heat sink for the power supply. He arranged them in the U-shaped form shown in the following pictures. That shape allowed him to fit (essentially) the same transformer as we use in the GT-101 power amplifier, making the power supply brawny enough to support the higher output power.

outside view showing replaced audio i/o connectors

outside view showing iec power connector

You'll note that Tim has retro-fit:

The end result is 120 Watts (60 Watts/channel) is the smaller footprint of a Stereo 80!

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