From Brian Willoughby Sent Thu, Jun 21st 2018, 03:36
On Jun 18, 2018, at 7:33 PM, Ivan Schwartz <xxxx.xxxxxxxx@xxx.xxx> = wrote: > Only active DI use phantom power; passive ones with transformers do = not need phantom. True. In addition, passive DI block the phantom power - DC cannot pass = through a transformer. So, not only do they not need phantom, but they = defeat phantom if it=E2=80=99s there. > The active circuits in a DI typically do not provide any gain. >=20 > Phantom power is current limited (thus the higher voltage) so there is = little power available for a real preamp design. Phantom powered mic = are usually putting out a mic level signal, not line level. A = 500-series rack power supply has much more current available, and the = bipolar power supply design allows for plenty of headroom. >=20 > The big issue I have using a DI for synths is that a typical DI is = designed to drop the signal to mic level, and then you use a mic preamp = to add gain. This is not an ideal situation in terms of gain staging = and optimizing signal to noise ratio. That is why devices like the = SynthDriver were designed. Agreed about non ideal gain staging. (unless you like adding noise) What=E2=80=99s the SynthDriver? Who makes it? I tried a quick search and = couldn=E2=80=99t find anything. Brian > Ivan >=20 > OnJune 13, 2018 at 8:16:52 PM, Brian Willoughby via analogue = <xxxxxxxx@xxxxxxxxx.xxx> wrote: >> Considering that DI products are almost always used in a situation = where phantom power is available, and potentially even where wall power = outlets might be in short supply, it makes sense that DI designers would = include the option to power everything from phantom power. >>=20 >> In addition, since phantom power is (supposed to be) 48V, that=E2=80=99= s a lot more power for a preamp than, say, the +/-16V of 500 Series = modules. >=20