12B4A SE
This micro-minidesign was found on the web and as it appeared to be super-simple
as well as rather powerful, I order the tubes from my favourite NOS-supplier
- Oldradioparts, Tubes and More; and the transformers
from EdgarAudio, a local (Swedish)
supplier of stuff for instrument amplifiers.
The main idea was to house the amplifier in a small wooden box, originally used for a dosimeter set. When the mains transformer arrived (ordered from Svebry), I noticed that it was to big for the space provided so I ordered a Hammond steel chassis instead.
To my disappointment, I had to drop a lot of voltage from the driver tube to the 12B4A's that everything inside the chassis got unfortable hot and I also had a lot of noise brom bad filtering.
This is yet another of those projects that never left the drawing board. Most of the 12B4 tubes I had, over 20 of them, were sold off, some given away and I may possible dig up a pair or two right now.
There were ideas of a simple single end amplifier based on the 12B4 and I even had one running to the Levinson schematic. However it ran really hot and showed a lot of hum, so it was scrapped.
SCHEMATICS
PHOTOS
Links
Single Ended 12B4A Integrated Amplifier (Part 1)
Single Ended 12B4A Integrated Amplifier (Part 2)