Lundahl Interstage transformer, LL1692A-18mA

Tube Amplifier Interstage Transformer / Line Output TransformerLL1692A-18mA

LL1692A is an interstage transformer for tube amplifiers, impedance-wise placed between LL1660 and LL1671. LL1692A 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. It has a special high flux, low distortion audio C-core of our own production.

The Push-Pull version is assembled with a small core air gap to allow for some DC current unbalance. For the S.E. versions of the LL1692A, the core air gap is chosen such that the denoted DC current (18mA for a LL1692A/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 approx. 0.7 T for the signal.

Weight: 0.75 Kg

Turns ratio: 1+1+1+1 : 1.75+1.75

Static resistance, winding A: 220 ?

Static resistance, winding B: 175 ?

Static resistance, winding C: 345 ?

Max. DC current through any single section: 70 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV

(*) The source impedances used in the tables indicate a recommended upper limit, unless the specified LF frequency response can be compromised. At lower source impedance, bass will improve but resonance peaking might occur. Peaking can be reduced using secondary load resistors or RC networks.