External PSU and transfer

Hi all…

I have some thoughts to make a four channel mic pre in a box and to use a external PSU. This is not my concern, but rather the transfer of the PSU to the mic pre box.

I have just limited experience with this using direct coupled cables for the job which resulted in a massive pack and cables and not very neat at all. I would like to use… let's say a 5-pin XLR-connectors for transferring B+, heater supply , phantom power and of course 0V/ ground.

My question is if there are specific cables that can handle this or is the idea wrong. What are the limits and pros and cons here?


Best regards

/John

I use this cable:

http://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15001&langId=44&urlRequestType=Base&partNumber=1891258&storeId=10151

and a 6 way XLR for this purpose.

http://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15001&langId=44&urlRequestType=Base&partNumber=1891258&storeId=10151

You need to extend the chassis of the mic pre to the chassis of the power supply and then to the mains safety earth and this is the purpose of the screen of the cable. I use the pins like this:

2 for heaters
2 for HT+ and 0V
One for 48V
One for chassis/screen/48V return

Cheers

Ian

Thank you Ian

Another question related to this is the possibility to individually turn of separate channels or is it preferable to just have a major power switch for all of them… maybe?

What do you say?


Best regards

/John

I do not see any advantage in turning off individual stages. You might save a little power is all. Leaving the heaters on is probably better than switching them on and off. In preamps, the amount of heat is quite small so you do not really need to worry too much about temperature rise.

Cheers

Ian

No, I guess you're right. And it would a little more complicated circuit to adjust for different current draws I suppose.

Ok, thank for the link to the cable. I'll have a serious look at it.

Best regards

/John