• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Lundahl LL1517. What is it good for?

Hi

The LL1517 is designed to be driven from a very low source impedance. The datasheet even mentions 'minus 18' as the optimum source. The frequency response is given when driven by a source resistance of 10 ohms, fed into 600R. Those are too low values for tubes. Ok, a white cathode follower may achieve a R out of 10 ohms and not distort to much when driving 600R, but that is about it in the 'tube world'.

Erik
 
CD-players do have low output impedances, but if it is as low as 10R I don't know. Best thing is to check your manual. It is also important to terminate this transformer with at least 600R. This can be a tough load, or introduce a LP cutoff in the output coupling cap (if present) is too low in value.

Chech the driving habilities of your CD-player! I don't know if the manual shows this information, however.
 
How did it work out? Normally an output transformer will have to be able to look into 10 - 50K input impedance on the secondary,
and sometimes more.

I have made some measurements on a Sowter 3603 that also is specified for a 600R load. It worked perfectly into 1 K, but showed
very bad results into 10K+, with severe 100 KHz ringing.
 
I stay corrected. I didn´t think of the possibility to wire the 4 windings separately. I have allways thought of them as 2 inputs and 2 outputs,
but that does not have to be the case.

It takes some time to get the head around audio transformers, and the manufactures don´t help much in that regard.