Tube Output Transformers
All OPTs are built to order in our dual coil single C-core style and can be ordered with a choice of core air-gap for Push-Pull or Single-Ended applications. Most of our OPTs can be configured for different primary and secondary impedances. For the comprehensive list of sub-types, please click here.
The use of C-cores with well-defined air-gap results in an almost constant inductance throughout the whole operating voltage range. For SE transformers, the primary inductance variation due to signal level is less than 7%.
Most of the transformers below are available with amorphous iron C-cores. The amorphous cores are considered to have sonic advantages, but the signal level capability with amorphous core is about 30% less than with a conventional silicon-iron C-core.
 
Special OPT for Electrostatic Speakers, click here.
 
 
 
Tube output transformers, sorted in Primary Impedance
 Model
Primary Impedance
Secondary impedance
Max power at 30Hz Push Pull
Max power at 30Hz Single Ended
Weight KG
Configuration
see data sheet
Price
USD
Suitable for tubes
600Ω
700W
140W
4.5
C
361.00
650Ω
250W
50W
2.5
C
241.00
680Ω
4Ω, 8Ω,16Ω
700W
140W
4.6
C,D,E
357.00
1K
360W
70W
4.5
B
361.00
1.2K
4Ω, 8Ω, 16Ω
125W
25W
2.5
B,C,D
241.00
1.2K
4Ω, 8Ω, 16Ω
360W
70W
4.6
B,C,D
387.00
1.2K
4Ω, 8Ω
180W
36W
2.5
C,D
available in AM & Ag, call for pricing
241.00
1.6K
4Ω, 8Ω, 16Ω
250W
50W
2.5
C,D,E
241.00
2K
4Ω, 8Ω, 16Ω
105W
21W
2.5
B,C,D
available in AM & Ag, call for pricing
241.00
2A3
2.3K
8Ω, 16Ω
180W
35W
4.5
B,C
361.00
KT66,2A3   
2.3K
8Ω, 16Ω
62W
13W
2.5
B,C
241.00
KT66,2A3
2.6K
4Ω, 8Ω, 16Ω
188W
36W
2.5
C,D,E
243.00
2A3
2.6K
8Ω, 16Ω
180W
35W
4.6
B,C
387.00
2A3 
3K
4Ω, 8Ω, 16Ω
125W
25W
2.5
B,C,D
241.00
300B,2A3
3K
8Ω, 16Ω
112W
2.2W
0.74
B,C
132.00
300B,2A3
3k
8Ω, 16Ω
112w
2.2W
0.74
B,C
Nanocrystalline core
301.00
300B,2A3  
3K
55W
10W
1.4
  
150.00
300B,2A3  
3K
5Ω tap
N/A
16W
2.5
288.00
300B,2A3  
3K
8Ω tap
N/A
16W
2.5
  
288.00
300B,2A3  
LL2785CAM
3K
  8Ω tap
N/A
16W
2.5
Amorphous core
482.00
300B,2A3
LL2785B
3K
special for Elekit TU8600, this OPT has a cathode feedback tap
288.00
300B,2A3 
Elekit TU8600
3.1K
105W
21W
2.5
3.1K : 5
241.00
300B,2A3  
3.2K
100W
20W
2.5
3.1K : 8
241.00
300B,2A3  
3.3K
4Ω, 8Ω, 16Ω
250W
50W
2.5
C,D,E
241.00
EL34,300B
845,2A3  
LL1620AM
3.3K
 4Ω, 8Ω, 16Ω
 250W
 50W
 2.5
 C,D,E
421.00
EL34,300B
845,2A3
3.3K
 4Ω, 8Ω, 16Ω
 250W
 50W
 2.5
 C,D,E
264.00
EL34,300B
845,2A3
LL1620AM-CFB
3.3K
 4Ω, 8Ω, 16Ω
 250W
 50W
 2.5
 C,D,E
445.00
EL34,300B
845,2A3
4.3K
4Ω & 8Ω
160W
N/A
2.5
Multi tap secondary OPT
289.00
EL34,KT88, KT120
4.5K
4Ω, 8Ω, 16Ω
105W
20W
2.5
B,C,D
243.00
EL34,KT88, KT120,845
4.6K
8Ω, 16Ω
45W
10W
2.5
B,C
available in AM & Ag, call for pricing
241.00
EL34,KT88
EL84,845
4.7K
5Ω & 8Ω
100W
20W
2.5
5+8 Elekit
241.00
EL34,KT88,
KT120,845
4.7K
5Ω, 8Ω
100W
20W
2.5
5Ω,8Ω
241.00
EL34,KT88,
KT120,845 
5K
40W
8W
1.4
  
150.00
EL34,KT88,
KT120,EL84
LL1663AM
 
5K
40W
8W
1.4
Amorphous core
330.00
KT88,KT120
EL84,845
LL1663Ag
 
5K
40W
8W
1.4
Silver wire
4098.00
KT88,KT120
EL84,845 
LL1663AgAM
 
5K
40W
8W
1.4
Silver wire and amorphous core
4365.00
KT88,KT120
EL84,845 
5.5K
4Ω, 8Ω, 16Ω
320W
60W
4.0
C,D,E
361.00
845
5.5K
40W
8W
1.4
  
150.00
EL84,845
LL1682AM
 
5.5K
40W
8W
1.4
Amorphous core
330.00
EL84,845
LL1682AgAM
 
5.5K
40W
8W
1.4
Silver wire and amorphous core
4098.00
EL84,845
5.6K
8Ω, 16Ω
62W
13W
2.5
B,C
241.00
845
6K
4Ω, 8Ω, 16Ω
125W
25W
2.5
B,C,D
241.00
845
6K
4Ω, 8Ω, 16Ω
24W
4W
0.75
B,C,D
132.00
EL84,845
6K
N/A, SE only!
5W
1.35
198.00
845
6.5K
4Ω, 8Ω, 16Ω
250W
50W
2.5
C,D,E
241.00
845
9K
160W
30W
4.6
  
361.00
300B,845
9.2K
4Ω, 8Ω, 16Ω
160W
30W
4.0
B,C,D
361.00
845
9.7K
8Ω, 16Ω
45W
9W
2.5
B,C`
243.00
845
10K
4Ω, 16Ω
160W
30W
4.6
  
361.00
845
11K
4Ω, 8Ω, 16Ω
125W
25W
2.5
B,C,D
241.00
845
11K
95W
18W
4.6
  
361.00
845
11.5K
8Ω, 16Ω
62W
13W
2.5
B,C
241.00
845
16K
4Ω, 16Ω
N/A
5W
1.4
  
150.00
10Y, 801A
EML20B
LL2735FAM
16K
 4Ω, 16Ω
N/A
5W
1.4
330.00
10Y, 801A
EML20B
16K
N/A
5W
1.4
  
150.00
10Y, 801A
EML20B 
LL2735BAM
 16K
 8Ω
 N/A
 5W
1.4
330.00
10Y, 801A
EML20B 
20K
4Ω, 16Ω
160W
30W
4.6
  
362.00
211
20K
160W
30W
4.6
  
362.00
211
LL1691BAg
20K
160W
30W
4.6
Silver wire
10513.00
211
23K
8Ω, 16Ω
62W
13W
2.5
B,C
241.00
To place an order, please send your inquiry with your complete shipping address to erhardaudio@gmail.com, thank you.