In The Audio Amateur issue 2 of 1981, two Dynaco ST150 amp modification articles appeared. One was titled ‘The ST-150-BJ-1 A Boak-Jung Modification of the Dynaco Stereo 150 Amplifier’, and it was authored by Pat Amer. This article was on the general ST150 modification process, and it included both circuit upgrades and a set of power regulation mods. The specific power mods were developed by Jim Boak, who also wrote a related article, titled ‘Power Modifications for the ST-150-BJ-1‘. This second article is definitely Dyna ST150 oriented, but Jim also wrote a more general version, within The Audio Amateur issue 1 of 1980, titled ‘A Family of Power Amplifier Regulated Power Supplies‘.
Not only do the articles describe a useful mod path for the Dyna ST150, but they are still generally applicable within almost any power amp, especially the power mods. Many thanks to Pat and Jim for their help in making these articles available.
We are happy to be able to make these three articles once more available, under the category of Guest Contributions. And, it is also a pleasure to renew contact with both Pat and Jim, after 30-plus years!