LL2766 2766

User Manual: 2766

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Small Size Tube Amplifier Output Transformer LL2766
LL2766 is a small size power output transformer for tube amplifiers. The transformer is available with different core air gap
for PP or SE drives.
The transformer has a special high flux, low distortion audio C-core of our own production.
The LL2766PP is assembled with a small core air gap to allow for some DC current unbalance.
For the S.E. versions of the LL2766, the core air gap is chosen such that the denoted DC current (50mA for a LL2766/50mA)
generates a no signal core flux density of 0.9 Tesla when used with all primaries in series. This leaves a flux density swing of
0.7 T for the signal.
Winding schematics, physical dimensions, pin and mounting hole layout (all dimensions in mm)

36

2
L (1)
13

16

18

21

13

5
K (40)

56

3

16

4 x M3
Mounting holes

M (2)

4
73

Bottom view

9
2 3 4 5

7 8 9 10

M (2)

21

8
K (40)

10

18
53

L (1)

61

Weight

Turns ratio

0.75 Kg

40+40 : 2+2+1+1

Static resistance,
winding M
0.3 

7

Static resistance,
winding L
0.6 

Static resistance,
winding K
140 

Max. current through any primary (“K”) section (4 W heat dissipation):
120 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV
Actual turns ratio
Max output voltage
Approx primary
Secondary
Secondary
RMS SE / PP
impedance
impedance
connection
6k

4

A

79:2

3V / 7V

6k

8

B

79:3

4.5V / 10V

6k

16

C

79:4

6V / 14V

3k

4

B

79:3

4.5V / 10V

3k

8

C

79:4

6V / 14V

3k

16

D

79:6

9V / 20V

Type

LL2766/PP
LL2766/30mA
LL2766/50mA

Primary
inducance

Primary
magnetizing
DC current for
0.9T

125H
43H
25H

30mA
50mA

Max output
power across 8
ohm @ 30Hz,
Sec. connection
B
12.5W
2.5W
2.5W

Max output
power across 8
ohm @30Hz,
Sec. connection
C
24W
4W
4W
R171130 PL

Lundahl Transformers AB, Norrtälje, Sweden, Phone +46 (0) 176-139 30, office@lundahl.se, www.lundahl.se

B+
Primary
connection
for
Single-End

B+
21

18

Primary
connection
for
Push-Pull

21

18

16

16

13

13

Indicates phase

Secondary
connection
A
(2)

Secondary
connection
C
(4)

10
9
8

Secondary
connection
B
(3)

10
9
8

7

7

5

5

4

4

3

3

2

2

10
9
8
7

Secondary
connection
D
(6)

10
9
8
7

5

5

4

4

3

3

2

2

Lundahl Transformers AB, Norrtälje, Sweden, Phone +46 (0) 176-139 30, office@lundahl.se, www.lundahl.se
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Page Count                      : 2
Language                        : en-US
Tagged PDF                      : Yes
Title                           : LL2766
Author                          : Anna Kvicker
Creator                         : Microsoft® Word 2013
Create Date                     : 2017:11:30 15:51:51+01:00
Modify Date                     : 2017:11:30 15:51:51+01:00
Producer                        : Microsoft® Word 2013
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