Tube cross-reference
EC81 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the EC81 power - triode single (under 10w). Compare core specifications and verify every restriction before using a replacement.
Exact variations of EC81
These designations belong to the same electrical variation group. Their names may differ because of international standards, manufacturing tolerances, or materials, but they are recorded as electrically equivalent—not merely substitutes.
6R4 Voltage - Triode (single high frequency)
- Base
- Not recorded
- Socket
- Not recorded
- Base pins
- Not recorded
- Sections
- 1
- Heater voltage
- 6.3 V
- Heater current
- 0.24 A
Replacement tubes for EC81
The following tubes are recorded as possible replacements for EC81. This direction does not establish that EC81 can replace them.
Voltage - Triode (single high frequency)
The database records 6R4 as a possible replacement forEC81.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Power - Triode Single (under 10W) | Voltage - Triode (single high frequency) |
| Construction | Triode | Triode |
| Base | Not recorded | Not recorded |
| Socket | B9A | Not recorded |
| Base pins | 9 | Not recorded |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.24 A | 0.24 A |
Where EC81 can be used as the replacement
In these recorded relationships, EC81 is the replacement tube. The listed original tubes are not automatically suitable as replacements for EC81.
Voltage - Triode (single high frequency)
The database records EC81 as a possible replacement for6R4.
No special restrictions are recorded for this substitution.
| Specification | EC81 replacement | Original tube |
|---|---|---|
| Tube type | Power - Triode Single (under 10W) | Voltage - Triode (single high frequency) |
| Construction | Triode | Triode |
| Base | Not recorded | Not recorded |
| Socket | B9A | Not recorded |
| Base pins | 9 | Not recorded |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.24 A | 0.24 A |
Verify before substituting
Matching a base or heater voltage is not enough to prove that two tubes are interchangeable. Check pin connections, heater current, maximum ratings, bias requirements, warm-up behavior, and the equipment manufacturer’s service documentation before making a substitution.
View the complete EC81 specifications →