Bob's Mods said:
Please try an describe the sonic difference between the passive xformer and the active DI box?
thanks all,
Bob the Mod guy
Sonically, it depends on the DI. But, in general, the better the DI, the better it will sound. The Countryman is just about always a safe bet. It is a quality DI.
Common wisdom (and technical theory) says this:
Passive instruments (magnetic/piezo pickups)- use an active DI
Active instruments/line level gear- use a passive DI
Why?
Active DIs have much higher input impedance than passive DIs. Passive pickups like to see very high input impedance, or they may suffer high-frequency rolloff and other tonal issues.
Passive DIs (generally) can handle hot input signals and transients better than active DIs, as instead of harsh electronic clipping, the transformer overloads in a smooth way.
That being said, sonically, it depends on the DI.
A cheap passive DI has a crappy transformer, which may not have full range response, and saturates with only modest signals, which further restricts it's range, and affects sound quality.
A cheap active just sounds like crap, and will overload at very low levels. Even decent actives can overload with a hot signal, if the battery is weak or the phantom power is lower than 48V.
Most of this stuff is pretty accepted info, but I have definitely seen cases where a passive DI sounds better than an active, on a passive source, where by theory an active DI should be used.
Electric bass, for instance, is very forgiving. As are
some acoustic instruments.