Κώστας Φ.
Truth hurts. Here's a teddy bear.
- Μηνύματα
- 8.978
- Reaction score
- 894
"The 211 creates a formidable impression because of its shape. But the 211 may appear old-fashioned and unsophisticated to high-brow maniacs for audio equipment. Perhaps this is the reason why there are only a few amplifiers that employ the 211 tube today.
This type of amplifier is a challenge from the viewpoint of the manufacturer. The power supply circuit cannot be normally designed, since the supply voltage required for the 211 tube must be approximately 1000V. In manufacturing the amplifier, we must pay utmost attention to moisture-proofing the chassis and proper insulation of the wiring so as to prevent hands from getting electric shock if one reaches into the amplifier.
However, it is only large triodes like the 211 that provide the best performance that vacuum tubes can offer. The Eg-Ip characteristic of the 211 and its brothers is more linear than most other power tubes. Larger diameter wire is used for the heater, the grid to heater spacing is considerable, and coarse "pitch" is used for the grid winding geometry. This type of vacuum tube is very sturdy and promises a high vacuum integrity, since it was originally intended for demanding commercial and military applications.
When high plate voltage is employed and the pitch of the grid is made more coarse, the amount of "stray electrons" around the heater is greatly decreased, thereby allowing the vacuum tube to work in a more closely ideal manner. In particular, the large triode vacuum tube functions mare perfectly when dealing with low level signals, allowing the tone quality to be clear and distinct. If the design of the driver stage is satisfactory, the single triode power amplifier possesses an unbelievably law distortion characteristic, even in the absence of negative feedback. This fact demonstrates the excellent performance of this family of vacuum tubes."
Ολόκληρο το άρθρο: enjoythemusic.com
Ongaku schematic: Click (pdf)
