
Amorphous Core High Level Line Input Transformer
LL1690
LL1690 is a high-level line input transformer with an uncut cobalt-based amorphous strip core. The transformer is
designed for high end audio applications such as tube amplifier line input with or without phase splitting. The
windings are arranged to give a high degree of symmetry if the transformer is used for phase splitting. The dual-coil
structure also greatly improves immunity to external magnetic fields from e.g. power supplies and motors. Primary
and secondary windings are separated by electrostatic shields.. The transformer is housed in a mu-metal can.
Turns ratio: 1 + 1 : 1 + 1
Pin layout (viewed from component side) and winding schematics:
Dimensions (L x W x H above PCB, in mm)
42 x 28 x 22
Spacing between pins
5.08 mm (0.2")
Spacing between rows of pins
30.5 mm (1.2")
Rec. PCB hole diameter:
1.5 mm
Weight:
81 g
Static resistance of each primary:
150 Ω
Static resistance of each secondary:
150 Ω
Distortion (primaries connected in series,
source impedance 600Ω ):
+ 23 dBU 0.1% @ 30 Hz
+ 26 dBU < 1 % @ 30 Hz
Self resonance point:
> 150 kHz
Suggested load for best square wave response, serial-serial
connection.
40k // 7k + 400pF
Frequency response (serial connection , source 1kΩ,
load 40 kΩ in parallel with 7k + 400pF):
10 Hz -- 100 kHz +/- 1.0 dB
Phase splitting balance (connection 2:1+1. Source 1kΩ,
load (20kΩ +20kΩ) in parallel with 7k + 400pF):,
>55dB, 10Hz – 50kHz
Phase response (deviation from linear phase)
(source 600 ohm, load 10k (Audio Precision))
20 Hz – 20kHz, < 2°
Isolation between windings/ between windings and shield: 3 kV / 1.5 kV
Connection alternatives and suggested applications:
R040113
Serial-serial connection (1 : 1) for high level line input
TRANSFORMERS
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
LL1690
Top view
Phase splitting for
1 : 1+1 input
Centertap
LL1690
Top view
LL1690
Top view
LL1690
Top view
Phase splitting for 2 : 1+1 input