Newbie Question on Phantom Power Distribution

I have half way through Bo Hansens 48v Phantom PSU

This is going to be a centralised PSU delivering Phantom Power to all my future DIY preamps


For ease of use and ruggedness (and they are cheaper than DC power sockets) I am using IEC sockets to send the 48v out...

One thing is bothering me ...
Do I send just 48v out of the unit or do I send 48v and 0V/Ground out of the unit?

UK,

:!: PLEASE DO NOT USE IEC CONNECTORS FOR ANYTHING ELSE THAN MAINS! :!:

It is utmost important to keep anything related to mains power separate from all signal lines. Using IEC-connectors will possibly confuse things - and one day when you're tired, you'll for sure plug in the wrong connector.

Better go for a DIN-connector, carrying both 0 and +48 - there are so many versions, that you'll never have to plug in a wrong one. Don't worry about connector resistance for phantom - current draw is wery small..

Jakob E.

[quote author="gyraf"]UK,

:!: PLEASE DO NOT USE IEC CONNECTORS FOR ANYTHING ELSE THAN MAINS! :!:

It is utmost important to keep anything related to mains power separate from all signal lines. Using IEC-connectors will possibly confuse things - and one day when you're tired, you'll for sure plug in the wrong connector.

Better go for a DIN-connector, carrying both 0 and +48 - there are so many versions, that you'll never have to plug in a wrong one. Don't worry about connector resistance for phantom - current draw is wery small..

Jakob E.[/quote]
oops - thanks for the advice....
I have already put the IEC conenctors into the box - so I am going to now use DIN connectors for the preamp ins....
So I will make up a few special coloured cables of IEC one end and DIN the other end.

can I just clarify - I do send 48v AND 0v down the line....

>can I just clarify - I do send 48v AND 0v down the line....

Yes, You send out the 48V and the GND...

otherwise, there is no reference point for the 48V measurement.

Yep, keep them together.

On the XLR end where the two 6K8 phantom resistors sit, connect 0V to pin1 directly at the XLR.

If you use it with a larger system - several micamps - connect phantom 0V to your analouge powersupply's 0V.

Jakob E.

[quote author="gyraf"]Yep, keep them together.

On the XLR end where the two 6K8 phantom resistors sit, connect 0V to pin1 directly at the XLR.

If you use it with a larger system - several micamps - connect phantom 0V to your analouge powersupply's 0V.

Jakob E.[/quote]
Jakob
I was going fine until the last paragraph
Now I am confused (don't worry it is not that hard a task to do... as my wife constantly reminds me...)

This is roughly what I plan


PSU 1 (being built)
Provides 48v >100mA Phantom Power
Currently 8 outputs to be hard wired to 8 yet to built mic preamps

PSU 2
e.g. Provides +15v/-15v

PSU 3
e.g. Provides +24v

PSU 4
e.g. Provides +18v/-18v

etc..
etc...

I haven't decided on what project to do next - that will drive what PSU I will have to build....

The reasoning behind this is that I am planning to build in effect a mixing desk via modules over time and don't want to build a PSU for each unit...

I will rack the PSUs away from the Desk and supply the power to the modules...

Sorry for the transgression - back to your statement

"If you use it with a larger system - several micamps - connect phantom 0V to your analouge powersupply's 0V."

I plan to have two Power DIN connectors for each module
one for 48v the other for +15/-15 or +24 or whatever...
Do you mean - connect it to the other Power in 0v ?
(just to clarify)

Yes. on a distributed power system, keep all 0V's connected.

Designing DC powersupplies for an "expandable" system is far from simple - you may need to rethink this system as it grows.

Jakob E.

PSU 2
e.g. Provides +15v/-15v

PSU 3
e.g. Provides +24v

PSU 4
e.g. Provides +18v/-18v

Click to expand...

You know, as you add more and more modules, and as the modules go farther and farther away from the main PS rack, these voltages may dip. and not be what you expect when it reaches the module.

What I am thinking is say have a +24-0-24V main PS.... then at the individual preamp modules, have a small regulator that will bring it down to +15-0-15, or 18-0-18, or whatever it needs...

The benefit I see with this approach is better voltage regulation and filtering, while keeping the hum-inducing transformers away. Downside is the need for more components (and expense, but not much).

It also provides a kinda fail-safe insurance to your preamp... you don't want plugging in a 18-0-18 to your 15-0-15 preamp. With the internal regulator approach, you're guarding the doorway, so to speak.