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← KT90
Rolling Candidates to replace KT90
Beam Tetrode — Octal
⚠ Safety
Drop-In Replacements
✓
6550
✓
6550A
✓
KT88
Top 10 Picks
KT77
drop-in
6.3V
⚠ Close, low Pa
6CD6G
drop-in
6.3V
⚠ Close, low Pa
6L6GC
drop-in
6.3V
⚠ Low Pa
7581
drop-in
6.3V
⚠ Low Pa
350B
drop-in
6.3V
⚠ Low Pa
5881
drop-in
6.3V
⚠ Low Pa
6N3C
drop-in
6.3V
⚠ Low Pa
6V6
drop-in
6.3V
⚠ Low Pa
6Y6
drop-in
6.3V
⚠ Low Pa
6W6
drop-in
6.3V
⚠ Low Pa
Rolling Candidates (102)
i
Heater:
4V
0
6.3V
4
●
8.4V
0
12.6V
0
13V
0
15V
0
18.9V
0
19V
0
21V
0
25V
0
26.5V
0
30V
0
33V
0
35V
0
45V
0
show all (15)
Fit:
Drop-in
0
Adapter
4
Status:
✓ Close
3
✓ Safe
1
⚠ Close, low Pa
2
⚠ Low Pa
96
4 shown (target 6.3V only)
▣ Compact
⚙ Thresholds filter
6.3V Heater
(4 candidates)
Tube
Status ↑
Pa
Ah
Fit
KT170
✓ Close
85
W
1.85
adapter
KT150
✓ Close
70
W
1.75
adapter
KT120
✓ Close
60
W
1.8
adapter
EL156
✓ Safe
50
W
1.9
adapter
Generated 2026-04-09
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