
High Current Tube Amplifier Interstage / Line Output Transformer
LL1671
LL1671 is a high current interstage / line output transformer for tube amplifiers. The transformer is available
with various core air gaps optimised for PP or SE drives.
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 LL1671PP is assembled with a small core air gap to allow for some DC current unbalance.
For the S.E. versions of the LL1671, the core air gap is chosen such that the denoted DC current (30mA for a
LL1671/30mA) 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)
Weight Turns ratio Static resistance,
Winding A
Static resistance,
winding B
Static resistance,
winding C
0.75 Kg 1+1+1+1 : 2+2
88 Ω 69 Ω 156 Ω
Max. current through any single section: 100 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV
Type
LL1671 PP LL1671 PP LL1671/30mA LL1671/30mA
Connection Alt M´´
PP to PP Interst.
2+2 : 2+2
Alt N
PP Line output
2+2 : 1
Alt Q
SE Line Output
4 : 1
Alt S
SE to SE Interst.
1 : 1
Primary DC current for
0.9 Tesla
- - 30 mA 30 mA
Primary Inductance 80 H 80 H 35 H 35 H
Freq. Response (+/-1dB)
@ source impedance (*)
Secondaries open
20 Hz – 25 kHz
5kΩ
15 Hz – 50 kHz
5kΩ
30Hz - 30 kHz
3 kΩ
Max output
voltage @ 30 Hz
2 x 150V r.m.s. 75V r.m.s. 33 V r.m.s. 130 V r.m.s.
Type
LL1671/30mA LL1671/30mA
Connection Alt T
SE to SE Interst.
1 : 2
Alt V
SE to PP Interst.
1 : 1 + 1
Primary DC current for
0.9 Tesla
60 mA 60 mA
Primary Inductance 10 H 10 H
Freq. Response (+/-1dB)
@ source impedance (*)
Secondaries open
40 Hz - 25 kHz
1 kΩ
40 Hz - 25 kHz
1 kΩ
Max output
voltage @ 30 Hz
130 V r.m.s. 130 V r.m.s.
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
13
16
4
3
5
2
21
18
A
B
8
9
B
7
10
A
C
C
(*) The source impedances used in
the tables indicates a recommended
upper limit, unless freq. response can
At lower source impedance resonance
peaking will occur. It can be reduced
using secondary load resistors.