Re: Remote Power Supply Connection

"West" <west@[EMAIL PROTECTED]
> wrote in message
news:JruWj.23633$5b3.10306@[EMAIL PROTECTED]
> I've built an out board power supply that (to me) looks kinda nifty, so
> I'd
> like to use handsome and modern connectors. Eons ago I was familiar with
> old
> and large but reliable Cinch Jones types of plugs and receptacles. But
> what
> is a better and craftier type plug, harness, and receptacle for today's
> audio equipment? The connections are: 12.6, 6.3, +/-5 &15, B+, Bias, and
2
> grounds. I might also make 1 or 2 control lines remote if I change my
> mind.
> A name and part number may be asking too much, but what the heck, I'll
> ask.
> All ideas and comments most welcomed. Thank you.
>


Hi West.  The situation might be different in the US,
but here in the EU you would run up against considerable
difficulties with the safety regs, and also with meeting
domestic insurance requirements.

When I started to build such an amp as you describe,
my M50 with a separate psu, I was surprised to find
that connectors rated for high DC voltage in industrial
or professional use were only rated at 70VDC for
domestic applications.

I came across a range of military grade NATO
screw connectors, by various manufacturers. They
were mainly painted "grey drab" or "military khaki"
However, I did find one firm, German, that could
supply nickel plated connectors, (maybe for the
Colonel's RT:-) . The company is part of the
Lapp Group, and the round connector is in their
Epic range.

A Google search will find their website.  There is
little point me giving you the part number I have as
it comes from the EU dealer (Farnell) catalogue.

I have used these for a several years on various projects
that require a separate psu.

http://www.kolumbus.fi/iain.churches/Pics/DCPowerConnector.jpg

I use the 9 pin connector, though 12, 18 and 24 pin types are
available, IIRC.  You *must*  use the centre pin for ground as it
is longer and more substantial than the other pins.  It connects
first and is the last connection to be broken when the cable
connector is removed. I try to follow some sort of a standard,
and use 1+2 and 3+4 for heaters. 5 for bias, 6 for B+ and 7+8
for the safety trip circuit.  9 as I say is ground.

EN 60065 very much dictates what we may or may not do in the
EU, but I could find nothing, or no-one that could tell me precisely
what the requirements or possibilities were for high voltage DC on
tube amps.

But I do know from conversation with professional tube builders
that solutions like the octal plug and socket are strictly forbidden
these days, in the EU  (I don't know about the US or Australia)

None of the builders I talked to would even consider an amp
with a separate high voltage DC supply.

So I tried another source of information, and spoke with
an industrial insurance inspector whom I had met at local
broadcast. I underlined the point that I was interested not
in industrial (broadcast) but domestic applications. He could
give me nothing firm, but made some recommendations
which would affect the safety evaluation decision made by
a company like his.   (Once again this info refers to
Scandinavia and may not be applicable to the US)

First he stresses that the DC cable needs to be as short
at possible and armoured, with a strong woven steel braid
connected to ground (So that your neighbour's prize winning
Doberman cannot chew its way through to your 450VDC,
electrocute itself, and leave you open to a huge compensation
settlement!)

Secondly, he stressed that the PSU must have a female connector
(pretty obvious really) with the male chassis connector at the amp
end.

Thirdly, there must be some method of shutting down the DC
instantaneously, if *either* end of the cable is disconnected.

Fourthly, the male connector, with the pins exposed must have
a diode on the B+ pin so that DC cannot get back from the
amp reservoir cap to the pins.

Last of all, he said that he would not be happy to see
>265VDC carried between the PSU and the amp,
unless they were mechanically joined together, and
the cabling was internal between the two units.


Hope this helps.

Cordially,
Iain