Tube cross-reference
EC91 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the EC91 voltage - triode (single high frequency). Compare core specifications and verify every restriction before using a replacement.
Exact variations of EC91
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.
6AQ4 Voltage - Triode (single)
- Base
- 7DT
- Socket
- Not recorded
- Base pins
- 7
- Sections
- 1
- Heater voltage
- 6.3 V
- Heater current
- 0.3 A
Replacement tubes for EC91
The following tubes are recorded as possible replacements for EC91. This direction does not establish that EC91 can replace them.
Voltage - Triode (single)
The database records 6AQ4 as a possible replacement forEC91.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage - Triode (single high frequency) | Voltage - Triode (single) |
| Construction | Triode | Triode |
| Base | Not recorded | 7DT |
| Socket | B7G | Not recorded |
| Base pins | Not recorded | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.3 A | 0.3 A |
Where EC91 can be used as the replacement
In these recorded relationships, EC91 is the replacement tube. The listed original tubes are not automatically suitable as replacements for EC91.
Voltage - Triode (single)
The database records EC91 as a possible replacement for6AQ4.
No special restrictions are recorded for this substitution.
| Specification | EC91 replacement | Original tube |
|---|---|---|
| Tube type | Voltage - Triode (single high frequency) | Voltage - Triode (single) |
| Construction | Triode | Triode |
| Base | Not recorded | 7DT |
| Socket | B7G | Not recorded |
| Base pins | Not recorded | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.3 A | 0.3 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 EC91 specifications →