
High Level Tube Amplifier Input Transformer
LL1674
The LL1674 is a large, high signal level audio transformer built with the well know Lundahl amorphous core.
The LL1674 consists of two coils, each with a two-sectioned primary winding and a high level secondary
winding separated by electrostatic shields. The core is a two-component amorphous strip core. The very high mu
of the core results in a phase shift of less than 0.5 degree at 10Hz.
The transformer is magnetically shielded by a mu metal housing.
Turns ratio: 1 + 1 : 4 + 4
Dims (Length x Width x Height above PCB (mm)): 43 x 28 x 21
Pin layout (viewed from component
side) and winding schematics:
Spacing between pins:
5.08 mm (0.2")
Spacing between rows of pins:
30.48mm (1.2")
Weight:
80 g
Rec. PCB hole diameter:
1.5 mm
Static resistance of each primary (average):
33Ω
Static resistance of each secondary (average):
605Ω
Distortion
(primaries connected in parallel, source impedance 150
Ω
):
22V rms (+29 dBU) secondary level,
30 Hz: 1%
22V rms (+29 dBU) secondary level,
50 Hz: 0.2%
Self resonance point :
70 kHz
Optimum termination for best frequency response
(source imp. 150
Ω
) :
No termination required
Frequency response
(source 150
Ω
, load 10k)
10Hz – 45kHz +/- 0.5dB
-3dB @ 80kHz
Isolation between primary and secondary windings/ between
windings and shield (rms):
3 kV / 1.5 kV
Suggested usage, 1: 4+4
R011127
Tibeliusgatan 7 International Domestic
SE-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
2
1
4
5
7
6
9
10
5
4
2
1
10
9
7
6
LL1674
(Top view)
8
5
4
2
1
10
9
7
6
LL1674
(To
view)
8
Indicates phase