jon- in the 1980s there were some battery powered products. They were very clean and all that, but didn't deliver current spurts well enough. Once the storage caps are drained, power out depends on power in. And battery changing is worse than tube rolling - is it fresh enough? Of course today's batteries are far better . . . there is merit in the concept.
Little-known historical factoid: In the early 80s the low-output moving coil phono cartridge became the norm, along with lots of problems interfacing with phono preamps. Even when their gain was sufficient, the preamp input stage often reacted with the delicate cartridge output to cause sonic degradation and even tracking problems. Jim developed a moving coil preamp which addressed the issues. His first patent was a new kind of circuit which took advantage of the extremely low signal levels, requiring virtually no power. Its electronics were essentially a bias-buffer, selectable via (8?) front panel buttons to best match the cartridge loading particulars. A 9 volt battery supplied the biasing voltage and was sealed along with the potted circuit inside the wooden cabinet, which was made of non-magnetic, non-conductive materials (wood and plastic laminate. No AC, no stray fields, no ripple. It performed extremely well.
Noel Lee took on exclusive marketing rights and Thiel made and shipped the units to Monster dealers. If you ever see a Monster head amp, the back panel, which we silk screen printed in our shop will say "Patented and Manufactured by Thiel.
I wonder how that head amp would hold up in today's world with higher expectations and better batteries, capacitors and resistors?
