Expensive transformer for bass DI?

[chrispenycate]

There's no doubting that a Jensen DI transformer will give a good sound, just whether, for a particular application, it's worth the not inconsiderable sum it costs. I have, over the years, collected a fair number of mic input transformers out of scrapped out tube studio gear (and occasionally installation PAs). I've found that these, while not designed for DI, gave a precision in the sound sufficiently exceeding miked speakers that I've frequently had to filter them down to prevent them invading the mix – live or studio. Driven fron a low impedance (which even a tube preamp should be), their frequency response is more than adequate, and at bass guitar frequencies (which do not descend into the chthonian depths like synthesizers and bass drums) they give masses of level for anything with a mic sensitivity input before any core saturation.

For the 10kΩ transformer mentioned above I'd recommend a cathode follower, or it won't be the transformer distorting but the tube driving it.

[phase_accurate]

What do you regard as expensive ? Here you can have transformers by Neutrik that go down to 30 hz and cost around USD 30 (probably more in the US) in the "naked" version. If you want one that is capsuled in u-metal then it costs about three times that much.

If you have a transformer with three windings you may probably use it with some NFB to further reduce THD and improve FR at the same time.

Regards

Charles

[ruffrecords]

The thing about transformers is that their bass response depends mainly on the primary inductance and the bigger the inductance the better the bass response. Obviously more inductance costs more money so it it is not surprising that a good transformer for a bass DI is going to be expensive. The cheap transformer made bu the likes of OEP have relatively low primary inductance and so are not ideal for bass DI. The more expensive makes like Sowter and Jensen generally have a much higher primary inductance and hence work better for bass DI.

Cheers

Ian