The tape recorder's manual is available with circuit diagrams [1] and more pictures [2]. I'm not seeing an hf bias oscillator in the circuit unless the manufacturers are being clever. It was half track mono with two speeds, 3.5 ips and 1.875 ips.

Someone did a lot of work to restore these recordings!

[1] https://manualmachine.com/concertone/tr100/8544644-schematic...

[2] https://www.radiomuseum.org/r/transicord_tr_100.html

https://youtu.be/YjRbmtrDJI4

For those of you who don’t know…John Coltrane is a legend in jazz music. Posted a YouTube link to an excellent work of his above.

And the recordist, Frank Tiberi, is a jazz saxophonist and has played with the Woody Herman big band (with whom I saw in the 70s). Also teaches at Berklee College of Music in Boston.

John Coltrane has a special meaning in jazz for me.

I don't see any other musician creating harmonies as rich as him. Yes, not even Miles Davis, Bill Evans or Tom Jobim (other jazz musicians that I like a lot).

It is surprising how fresh and accessible his music remains today. He never became a top hit, but also never stopped being relevant.

When you say accessible I guess you're excluding his free jazz period. And "rich" harmonies doesn't really mean anything. If you're saying that he stacks more extensions than Bill Evans, that seems hard to quantify.

I picked a hell of a day to stop impulse shopping.