No.43
Hi-Fi Audio
6N1P
Using the Svetlana 6N1P Dual Triode in New
or Existing Designs
By: Eric Barbour
The Svetlana 6N1P is a medium-mu dual miniature triode with a unique
Russian-originated design. Its construction is not like that
of a typical concentric-grid triode such as the 12AU7, nor
is it a "frame grid" construction like the 6DJ8/6922/ECC88;
its grid structure has features of both families. Originally
designed for cathode-follower service in pulse power systems,
it also happens to possess very low signal distortion in typical
RC-coupled audio circuits. Figure 1 shows that the 6N1P's
linearity is competitive with, and in some cases superior
to, commonly-available dual medium-mu triodes.
Audiophiles all over the world have discovered that the 6N1P works very well in the 6DJ8/6922/ECC88 sockets in their equipment. Some have commented that it is less microphonic than low-cost 6DJ8/6922 types currently on the market. The 6N1P has been reported to work in the driver stages of current power amplifier models by Audio Research, Sonic Frontiers and Conrad-Johnson. Although not an exact 6DJ8 replacement, it is similar enough to deliver very good performance.
The major issue with its operation in existing 6DJ8 audio equipment is the heater consumption, which is 600 milliamps (versus 365 milliamps in a 6DJ8-family type). Some high-end preamplifiers might have difficulty providing the extra heater current, so we strongly recommend contacting the preamp manufacturer about the usability of the 6N1P in their product.
For new design, the circuit may be kept in the 6DJ8 form, provided the heater power supply is upgraded for the 6N1P. If 6DJ8 compatibility is not desired, the gain stage designs shown in Figure 2 are recommended. Bias requirements for the 6N1P are different from the 6DJ8 family, requiring less negative grid voltage to reach the same anode current. If the two triodes in a 6N1P are used for different signals, grounding the internal shield (pin 9) is recommended.
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**The information provided in this application note is intended for general design guidance only. The user assumes all responsibility for correct and safe usage of this information. Svetlana Electron Devices does not guarantee the usefulness or marketability of products based on this material.