Re: Remote Power Supply Connection

On May 21, 12:20 pm, Patrick Turner <i...@xxxxxxxxxxxxxxxxxx> wrote:

No connector should be "solid" at any end in this sort of
applications. Both ends should be suitably socketed against the sort
of eventuality you describe. Mil.Spec. connectors and some medical
connectors, machine-tool connectors and others are locking-types for
very good reasons - the consequences of a fall such as you describe
may be far less than an accidental unplugging - but that sort of
equipment has suitable strain-relief designs as well.

There are not many plug and socket designs which can withstand sideways
forces of say 20 times the weight of an amp or PSU due to one or the
other
falling off a bench and being halted in the fall by a cable.
So the umbilicals MUST be longer than 1.2 metres, so that if an amp
chassis and psu
are both on a table or bench of say 750mm height then
a fall to the floor by either chassis doesn't wreck a cable or the
connector.

That is the point. And a fall is not the only potential for forcible,
sudden plug removal. There are tripping persons, running dogs (pun
intended), even small children who might get involved if
unsupervised.

1.5M is a nice length, and if too long one loop tied up with
a loop of masking tape won't hurt.

No, it won't and I agree, a good length.
But remote PSU should be REMOTE, so on the floor they go!

The turn on switch should be on the amp chassis and turn on
is achieved by the switch grounding one end of a relay coil requiring
12Vdc.
In the psu chassis the live end of the relay coil is connected to a 5VA
12Vdc auxiliary dc supply.
This supply also sends 12Vdc to the amp chassis to operate active
protection measures.

So there is NO access needed for the psu, and with its silicon diodes
its just like a gigantic plug pack, outa sight and outa mind.
No need to worry about it.

I would posit the umbilical should be male at the P/S, female at the
Amp.

Huh?, I always have a female chassis socket at th psu, and the cable is
hard wired into the
amp and has one male plug. Is that what you meant?

Nossir. My *preference* would be that neither the amp nor the PSU are
hard-wired, but the umbilical is a separate entity plugged at both
ends with appropriate opposite receptacles at each box.

 The strain-relief to the (presumably armored) cable should be

sufficient to carry the weight of either end, but, again, the
connector should come apart well before umbilical failure. And given a
proper design along the lines Patrick has described, DC voltages would
either drop within a few millesconds, or be entirely disconnected. The
days of the old Dynaco/Eico octal plugs at either end of the umbilical
to octal sockets at either component is simply nuts any more - 'cept
for Bret, of course.

I think octal plugs and octal valve sockets are fine.

And you take the appropriate measures to make sure that this is so.
Writing only for myself, and these days, I would not use them were I
in that position. And this for TWO (2) reasons: 1. Better means are
available that handle all the heroics, shields and set-backs as part
of the design. 2. I have not, will never, make a custom amp for
another person. Accordingly, expense is no object when I do things of
this nature, so spending $100 - $150 or so on the appropriate
connectors with strain-relief and freeloading from any of several
sources I have the appropriate Armor-Flex cable would be my choice.
Crane cables are excellent, especially the sort with the steel mesh
below the first layer of rubber insulation. They can get a bit fat,
but not really a big deal.

And we have all three potential threats in this household on a regular
basis -large, active dogs, sometimes clumsy people and small, very
curious, very active children. Hence my "placement" of tube equipment
in this house even if covered - high and out of reach.

Very convenient actually.
If they are yanked straight, iti's good that they pull out easy.

I use an old tube base, solder up all the wires well, and drill out the
spigot
and place a 4mm threaded rod inside projecting back up where the wires
are.
This re-inforces the spigot which can often get broken off when someone
treads on plug.
120Kg audiophiles are like big dopey elephants sometimes.
I sometimes cut off the bakelight or plastic surround down to the botton
of the base level.
Then I get some PVC conduit and cut a 30mm length which fits snugly
around the
plug with its soldered wires. One ends up with a very rugged plug
costing almost nothing,
and one that can be easily replaced by cutting a damaged one off and
placing a new made one on.
Finally, I pour it some polyester resin to fill the plug to stop wire
movement
and bind it all together.

Its possible to also glue a second PVC tube over the final plug so this
tube projects
slightly further than the location spigot, tand thus it shrouds the
pins.
But I have never bothered because octal sockets made to allow a shroud
to push in
are not made afaik, and are too hard to diy.
I have 20mm plywood blocks around the octal sockets with a neat sliding
fit for the
plug. This prevents side ways foces on the cable from yanking the plug
over
and bending pins.

The beauty of the octal plug ans socket is that it IS designed for tube
amp voltages and currents

And heat. Don't forget the heat on those bases.

In one other amp I have here I have ONE psu chassis for two power amp
channels
which are on one chassis. I have three octal plugs and sockets and 3
mobile crane wire
cables twisted and bound together; extremely rugged cabling.
This set up was the first lot I did, and is for my own use only.
I have never had any troubles.

Come back in 200 years and the cables will be fine.

Very most likely. Just not in this house - for now, for the reasons
stated.

Peter Wieck
Melrose Park, PA
.

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