RFZ V781 racked - pix inside

[fgan81]

That is what the seller said:

The PSU-2448 has a (-24V) and (+24V) and (+48V) output, all with respect to GND.

So if you need -24V, just use the -24V output of the supply.  And +48V is your normal phantom power. Both are referenced with respect to GND terminal of the PSU.

Sounds good!

Which kind of output 1:1 transformer is good and cheap and fits to this project?

The V781´s are not tested yet but there are in good condition.

I have 3 * V781 and eventualy a RFZ PSU N 706.
Do you know if the RFZ N 706 could powering up the tree Units?
I need also 6 1:1 Tranformers, right? Any Special type?
What is about Phantom Power? Any DIY Projects?
And last question, do you know similar racking up and good documentated diy Projects?

Hey fgan81,

with two N706 you could power a whole console. So it is way over for 3x V781. But still it can be done.
One V781 needs typically 45mA. Say not more than 80mA.

Are you aware of the fact that the V781 need -24V supply and how to handle this? Ground is on positive rail.
This is why you possible can not use the supply you linked together with the phantom. But you better ask the seller if it is possible to get positive rail grounded on the 24V side and stack the 48V on top.
Anyway I'd not build it with the N706. Recapping the thing alone will probably  cost more than building a new one with halve the weight.  But if you do not plan to travel with your preamps and as you already have it... why not. 

First of all before racking them, have you tested the units? Are they working and in good condition?
I am asking, because I know them quite well and I had lots of troubles repairing those. But mine came from an old recording truck and were in heavy use.
Would be a shame if you build a cool rack, plug them in and then..... nothing.

You do not need an output transformer if you want to run them unsymetrical. Thats totaly fine.
But most of the 1:1 will do a good job.

And I think there is no documentation for a V781 rackjob here.  But who knows.

best,
Stephan

 

[YannLu]

Hi there

Does anyone know what are the 3 trimpots for ?
I guess there for adjustment...

 

[Gemmegemme]

I have scans of the service manual including the schematic. I will make them available asap.

Bonjour, hello Michael ! So do you still have the manual & schematic for the RFZ VZ 781?
If you still have it, can you send me a copy to [email protected].
Thank you very much in advance,
Best regards , Jean

 

[jokeramik]

Look here: www.rfzderddr.de
If you need an adapter with transformer coupled output look here: Tools
Best regards!

 

[jokeramik]

Hi there

Does anyone know what are the 3 trimpots for ?
I guess there for adjustment...

Two pots are for the adjustment of the two discrete OPA and one is for adjustment of the internal voltage filter circuit.
Best regrads!