Using a 6 Pin XLR for a Tube Preamp PSU?

[smilan]

Hi, I have an old Ampex 602 preamp and I would like to put the PSU away from the pre amp for a quieter operation.
I need to send the following currents from the PSU to the preamp:
340 VDC @ 35mA = 11.9W (B+)
13.8 VDC @700mA = 9.66W (DC filament)
6.3 ACV @ 400mA = 2.52W (AC filament for the oscillator)
I'm thinking of using a 6 pins XLR connector.
The XLR datasheet says:
Rated voltage < 50 V
Rated current per contact 7,5 A
50V at 7.5A = 375W
So my question is: can I use >50V with low currents as long as I'm keeping the power way under 375W per pin?

 

[rock soderstrom]

I would rather take something like this. For example Lumberg.

https://www.distrelec.de/en/cable-socket-5a-160v-poles-socket-lumberg-connect-gmbh-kv-60/p/14402931?itemList=compatible

The data sheet says (in contradiction to the website) that this connector can withstand 250V and 5A up to the 7-pole version.

I have used this myself for 180V and 0.3A for a mic, no problem so far.

 

[ruffrecords]

If you look at the Neutrik spec for a 6 pole XLR it recommends not using voltages above 50V. But if you read the Amphenol data sheet it says the 6 pins is good for 250V. I use these for the power connection for the poor man's tube mixer. The only problem is it is very hard to wire all 6 pins and properly insulate the wires from each other. I am on the lookout for a connector with more widely spaced pins.

Cheers

Ian

 

[nielsk]

Use a Switchcraft?
I would be more concerned about the current, but seeing as XLRs are used for tube power supplies commonly and I have yet to see one fail, you could try it and see if it ever warms up. I would be very surprised if 350 VDC at 35 mA causes arcing.
I would be more concerned about the AC and having to shield that from the DC. It can be difficult to stuff that much in an XLR.
What is the oscillator for? Usually there are sections of tape electronics that are not used in a preamp only application, you can disconnect them...

 

[JohnRoberts]

Whatever connector you use, I hope the male pins are not energized when disconnected.

Putting the female connector on the power supply might reduce accidental contact to high voltages when unplugged.

JR

 

[radardoug]

XLRs are a good connector, but there are any number of other more suitable connectors. Check the usual suppliers. You can also find connectors with an extended earth pin, so the earth mates first/last.

 

[smilan]

Thank you all for your comments.
For now I ended up with a 4 pin XLR (0V, B+, DC heaters + and DC heaters -).

What is the oscillator for? Usually there are sections of tape electronics that are not used in a preamp only application, you can disconnect them...

The oscillator tube was disconnected for years but the AC line was used to power the VU meter's bulbs and an LED on/off indicator. Yesterday I connected the bulbs and the LED to the 6DJ8 6.3 DC supply to eliminate the need for an AC supply.

In future I might use the 6.3 AC line to run a 48V phantom supply by using a rectifier and a dc to dc converter lick this one, so I'll need an extra pin for the +48V.