Re: [AH] Using DI BOX with synths?

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