
Tube Amplifier Phase Splitting Interstage Transformer
LL1660S
LL1660S is a version of LL1660 with internal Faraday shields to improve balance in phase splitting interstage
applications. The transformer is available with different core air gap for different driving tubes.
The transformer is wound with a special low capacitance winding technique to achieve best high frequency
performance. The transformer has a special high flux, low distortion audio C-core of our own production.
The LL1660S is assembled with a small core air gap to allow for some DC current unbalance.
For the L1660S, the core air gap is chosen such that the denoted DC current (18mA for a LL1660S/18mA)
generates a no signal core flux density of 0.9 Tesla when used with windings 2 through 10 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)
Weight Turns ratio Static resistance,
winding A
Static resistance,
winding B
Static resistance,
winding C
0.75 Kg 1+1+1+1 : 2.25+2.25
315 Ω 240 Ω 625 Ω
Max. current through any single section: 50 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV
Type
LL1660S/PP LL1660S/10mA
Connection Alt A
PP to PP Interst.
2.25+2.25 : 2+2
Alt B
SE to PP Interst.
2.25 : 2 + 2
Primary DC current for
0.9 Tesla
- 18 mA
Primary Inductance 290H 42H
Freq. Response (+/-1dB)
@ source impedance (*)
Secondaries open
20 Hz – 25 kHz
15kΩ
25 Hz - 30 kHz
3.5kΩ
Max output
voltage @ 30 Hz
2 x 260V r.m.s. 220 V r.m.s.
R030220
73
Bottom view
4 x M3
Mounting holes
36
56
TRANSFORMERS
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
2
3
4
5
7
8
9
10
13
16
18
21
15
16
4
3
5
2
21
20
A
B
8
9
B
7
10
A
C
C
15
20
13
18
Distance between pins 0.2” (5.08mm)
Distance between rows of pins 1.8” (45.7 mm)
Pin diameter 1.2 - 1.4 mm