So often when we read of a modification on a classic piece of tube electronics we prepare to wince, as such work often results in senseless butchery of a well-preserved survivor. With [Frank Olson]’s work on a 1958 Ampex 601 tape recorder though we were pleasantly surprised, because while he makes a modification to allow its use as a stand-alone microphone preamplifier he also performs an extremely sympathetic upgrade to modern components and retains it in substantially the form it left the Ampex factory.

The video below the break is a satisfying wallow in pre-PCB-era construction for any of the generation who cut their teeth on tube, chassis, and tag strip electronics. We can almost smell the phenolic as he carefully removes time-expired capacitors and fits modern replacements complete with period features such as sheathing over their leads. The larger multiway can electrolytics are left in the chassis, with their modern miniaturised equivalents nestling underneath them out of sight. We all know that electronic components have become a lot smaller over the decades, but it’s still a bit of a shock to see just how tiny even a high voltage electrolytic has become.

The Ampex would have been a very high quality tape recorder when new, and while this one has a problem with its mechanism it’s that quality that makes it easier for him to do this work in 2020. There’s every chance that this one could be returned to service as a tape recorder if someone was of a mind to fix it, and meanwhile it will give Frank excellent service as a high quality pre-amp. This is how resto-mods should be done!

Ampex are very much still in existence making digital storage products, but back in the 1950s they were at the forefront of analogue magnetic tape technology. We’ve written in the past about how Bing Crosby had a hand in the development of high quality tape recorders, and also about Ampex’s part in the gestation of the video recorder.

Continue reading “A 1950s Ampex Tape Recorder Microphone Preamplifier Restoration” →