On 11/02/15 13:58, David Christensen wrote:
On 02/10/2015 05:43 PM, Len Ovens wrote:
As an aside... I don't think I will need it at this point, The isolation
boxes that are easy to get are "DI" boxes tha go from high impedance
unball to low impedance bal. Would these still work to go from a
ballanced output to an unballanced input?
DI boxes are designed to connect an unbalanced output to a balanced
input. I've also pondered running DI boxes "backwards". From a
technical view, I'd need to study the schematics of the driving
equipment, the DI box, and the driven equipment to convince myself
that it could work and not damage anything. I might try calling
technical support. From a execution view, I'd need the right adapter
cables (such as XLR-F to XLR-F). But from a conservative/ safety
view, I'd rather hook everything up the way the equipment
manufacturers tell me to and not have to worry about it.
Or do I need a one to one
isolator? Or does it depend on the powered monitor?
I'd look in the monitor manual and follow the manufacturer's
instructions. If you don't have a manual and can't get direction from
the manufacturer, I'd use an isolation transformer with suitable
connectors and cables.
How does this one look: http://www.rolls.com/pdf/M_HE18.pdf
That looks useful.
Having "solved" my problem with a single power source, would it still be
worth while isolating all stage amps from the mixer?
If the mixer has balanced outputs, the stage amplifiers have balanced
inputs, and both are powered from the same supply, isolation
transformers should not be necessary. I'd run balanced cables from
the mixer to the amps and call it good. That said, good isolation
transformers will cause a small lose of signal and fidelity, but they
might provide protection for certain equipment failures or operator
errors.
I think I will run
ballanced audio through the snake and do the cable adapting at the stage
end anyway.
It is best to keep balanced signals in balanced cables for as far as
practical.
Right now there is a TS plugged directly into a TRS mixer
output which means the signal minus is grounded.
I wouldn't plug a TS cable into an balanced TRS output. First, you
are shorting one half of the balanced driver output circuit. Second,
you are injecting chassis ground noise into the audio circuits.
Agreed. If you run balanced -> unbalanced, it's probably best to run
shielded twisted core from the output and just leave the shield
disconnected at the input. It's discussed in those Rane docs I posted.
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