Using DP for Live Backing Tracks (Stems or Mix?)

[daniel.sneed]

Hey James! Some days later, here it is.
I wish it may help you in your project.
Of course, feel free to ask anything around.

Connecting a line input to a mic input
Goal :
- Source may provide any type of +4dB line signal including
balanced floating, balanced non-floating, unbalanced.
- Mixer mic inputs may send 48V phantom power without damage.
- Ground-lift button needed.

I made experiments with many transformers and many di-boxes.
During experiment, I encountered many signal level problems (distorsion) and many sub-bass loss (at high levels), and some various other signal degradations.

My understanding is that transformer manufacturers provide data-sheets with very good specifications, but they will mostly not apply with real world equipments.
Data-sheets are often stated for: source output Z<10 Ω, input load Z>20 kΩ, which is rare to say the least.

By far, my best results have been with a Lundahl step-down transformer
The transformer ratio is 7:1, which means around -16dB gain.

The transformer is a Lundahl 1576, wired to achieve 7:1 ratio.
In fact this is a mic input transformer, used in reverse mode. That is to say line to mic signal flow.
Datasheet is here:
http://www.lundahl.se/wp-content/upload ... 576_77.pdf
Price is around 80 $ each