General purpose audio transformers

General purpose audio transformers for ground isolation, for splitting and for balanced-to-unbalanced conversion.

General properties:
Many different connection alternatives possible
Moderate copper resistance (50 Ω per section typically)
Medium signal level capability (Max 10 dBU at 50 Hz per section typically)
Excellent magnetic and electrostatic shielding
High mu cores (mu metal or amorphous strip core)

Isolation transformers

Type	Turns Ratio	Size LxWxH	Max Primlevel	Applications / Comments
LL1527	1+1 : 1+1	38x24x17	+16 dBU	The "standard" problem solver. Ground isolation, MS decoding, splitting 1 direct + 1 isolated outputs. Mic input 200:800 Ω.
LL1527A	1+1 : 1+1	38x24x17	+16 dBU	As LL 1527. Secondary shields available individually on connector pins.
LL1527XL	1+1 :1+1	38x24x20.5	+19 dBU	As LL1527, but with + 3 dB level capability compared to the LL1527.
LL1532	1+1 : 2	28x17x15	+10 dBU	A small size audio transformer. For isolation and microphone input (200:800 Ω).
LL1570	1+1 : 1+1	38x24x17	+16 dBU	Splitting 1 direct + 1 isolated outputs. Extra wide bandwidth. Microphone input (200 : 800 Ω).
LL1570XL	1+1 : 1+1	38x24x20.5	+19 dBU	As LL1570, but with + 3 dB level capability compared to the LL1570.
LL1588	1+1 : 1+1	47x28x24	+28 dBU	High level isolation applications 1:2 microphone input. Phase splitting.
LL1591	1+1 : 1+1	37x22x17	+16 dBU	”Naked” LL1527 -> no Faraday shields and no mu metal housing. Not for demanding applications.
LL1593	1+1 : 2	28x17x14	+12 dBU	”Naked” LL1532 -> no Faraday shields and no mu metal housing. Not for demanding applications.
LL1684	1+1 : 1+1	42x28x22	+25 dBU	Amorphous core version of LL1588. High level isolation applications 1:2 microphone input. Phase splitting.
LL1684	1+1 : 1+1	42x28x22	+25 dBU	Amorphous core version of LL1588. High level isolation applications 1:2 microphone input. Phase splitting.
LL7902	1+1+1+1 :1+1+1+1	66x32x21	+28 dBU	High level high quality general purpose transformer for very demanding applications. "When only the best is good enough".

Splitting transformers

Type	Turn Ratio	Size LxWxH	Max Primlevel	Applications / Comments
LL1581XL	1+1 : 1+1	38x24x20.5	+13 dBU (Prim in parallel)	Splitting 1 direct + 2 isolated outputs. Very high immunity to external magnetic fields and to large ground differences.
LL1583	1 : 1+1	28x17x15	+8 dBU	Splitting 1 direct + 2 isolated outputs. Small size mic. level transformer with the same excellent noise immunity as the LL1581XL.
LL1590	1 : 1+1+1	47x28x23	+13 dBU	Splitting1 direct + 3 isolated outputs.
LL7904	1+1: 1+1	66x32x21	+23dBU (Prim. in parallel	Very high level splitting transformer for 1 direct + 2 isolated outputs. Very high immunity to external magnetic fields and to large ground differences.

Transformer DIN unit

Lundahl transformers DIN unitjpg

Most of the transformers above can be mounted in our DIN housing using our kit, for easy onsite installation.

For your convenience, the following selected units are fully assembled and ready to install.

Complete DIN units

Pre-assembled units with screw terminals, ready to install

Photo	Type	Applications / Comments
	DIN1527	Provides galvanic isolation and splitting 1 direct + 1 isolated. It is suitable for low-to-medium signal levels.
	DIN1581XL	Provides galvanic isolation and splitting 1 direct + 1 isolated. It is suitable for medium-to-high signal levels.
	DIN1588	Is intended for splitting 1 direct + 2 isolated. It is suitable for mic and line level signals up to +13 dBU.