WHY 600 OHMS? There is a lot of history and some confusion here. The ideal impedance for driving an audio line is zero ohms and the ideal input impedance for connecting to it is infinity. The actual wire does not need to have any particular "characteristic impedance" nor does it need to be terminated like radio frequency cable. 600 ohms is a nominal value used to describe an environment.
In summary it could be said that a line driver should have an impedance no more than 600 ohms and a receiver should have an impedance no less than 600 ohms. If both driver and receiver were both 600 ohms however, half the signal would be lost in the driver. In a small system the designer may try to make the receiver impedance a factor of 5 greater than the driver but in a large or very noisy environment a factor of 10 might be attempted.

NEW SOWTER PRODUCTS We are introducing several new products for developers of studio compressors, pre-amplifiers etc using tubes or transistors. Also for converting computer sound cards, home cinema, DVD systems or most power amplifiers to balanced inputs. The list below includes some new and some existing products.

VINTAGE STUDIO EQUIPMENT We have a number of transformers available for vintage studio equipment repair or recreation. See our pro-vintage page

CUSTOM DESIGN SERVICE We are extending our custom design service to include this type of transformer. We will not make a charge for the design provided we accept the requirement as being of general interest. We can work from circuits, actual transformers loaned to us or from specifications. We may offer the service on a "best efforts" basis if we cannot be sure of meeting a particular performance.