Lundahl Line output transformer, LL1689S-18mA

Line Output Transformer LL1689S-18mA
(With a static shield, between the input and output, avoiding unwanted signals to go INTO the pre amplifier via the output cables)

LL1689 is a line output transformer for tube amplifiers. The transformer is available with different core air gap for PP or SE drives.

The transformer primaries are 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 LL1689PP is assembled with a small core air gap to allow for some DC current unbalance. For the S.E. versions of the LL1689, the core air gap is chosen such that the denoted DC current (18mA for a LL1689/18mA) 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.

Weight 0.75 Kg
Turns ratio 9+9 : 1+1+1+1
Static resistance, winding A: 19W
Static resistance, winding B: 15 W
Static resistance, winding C: 655 W

(*) The source impedances used in the tables indicates a recommended upper limit, unless freq. response can be compromised. At lower source impedance resonance peaking will occur. It can be reduced using secondary load resistors.