Quick Output Transformer Question

[dsavitsk]

I am going to use a pair of the Edcor transformers for a headphone amp. My headphones are 32 ohm, and I'll probably put a 32 ohm resistor in parallel. Do I need to do anything different to use the amp as a preamp? That is, will seeing a 10K, or a 50K input impedence cause reflection problems? Will I need to use a different resistor on the secondaries, or would transformers with a 600 ohm tap be a better idea? Thoughts?

 

[leadbelly]

These would work with a tube that could handle a 2K load:

http://www.edcorusa.com/classx/matching/xsm/XSM10k-150.htm

I'm no guru, but the fact that they are interleaved whereas the $17 ones are not would work to your benefit.

 

[dsavitsk]

They are certainly cheap enough to try them both, so I may do that. If the tube wants a higher impedence, could I simply add a resistor in series with the headphones?

And, to the original question ... is the 16 ohm output okay as a line stage or will there be frequency problems?

 

[Geek]

You want the tubes to see a constant load for best fidelity.

Using an Edcor with an 8 ohm secondary, then paralleling a pair of 18 ohm resistors (9 ohms) will provide an excellent load match with 32 ohm phones.

I did some experiments with this on my 6FD7 amp, which has a switched headphone output and XSE15-8-5K's and it seems optimum.

 

[ttan98]

Hello fellows,

Do you know which company(ies) makes VERY high QUALITY transformers, single ended and Push pull, in the states and international?

Edcor?, Hammond? Sowter? etc

 

[Geek]

If you mean DC to daylight with zero phase shift ( 😀 ), I hear Lundahl is a good place to start 🙂