Hiss from DI?

[Axtman]

The sound guy told me after practice that his was getting a hiss from my set up. After checking the bass, cables, etc. we determined that the hiss was coming from the DI box itself. I use a passive Proco DB-1. When I just plug in the DI alone to the snake, I get a hiss. It's low and not very audible, but the sound guys sees it on his laptop connected to the Presonus Live board.

This just seems weird to me. The things we might check out are to see if phantom power is some how going to the DI and check another line in the snake.

BTW, a while ago I noticed an audible hum coming from my set up and determined that if that DI box is right next to the power strip (and wall warts) that it induces a hum. This also surprises me since the DI box is all metal!

Your thoughts please.

 

[Downunderwonder]

Did sound guy make any attempt to low pass the bass below the hiss? Shouldn't be hard with his digital desk so long as it's pure hiss.

 

[T-Bird]

Hi.

This just seems weird to me. The things we might check out are to see if phantom power is some how going to the DI and check another line in the snake.

Did the 4KHz LPF affect the level of the hiss?

I assume that the "Floating Transformer-Balanced XLR Output" means an isolation transformer, and in that case, about the only possible causes are the speaker level pad resistor hissing (unlikely) and the ~200 Ohm output impedance being incompatible with the input of the Presonus (rather unlikely as well).

A broken connection or a cold solder should cause distortion across the frequency band, not just hiss.

Phantom power can saturate the transformer core, but the result should be (again) distortion not hiss.

Some cables are known to hiss on their own, perhaps eliminate the snake for testing purposes.

BTW, a while ago I noticed an audible hum coming from my set up and determined that if that DI box is right next to the power strip (and wall warts) that it induces a hum. This also surprises me since the DI box is all metal!

There's probably a broken cable shield in Your setup.

Regards
Sam