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Sourcing sockets and plugs for power supply umbilicals

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jmillerdoc

jmillerdoc

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Joined 2009
#1
I have seen several DIY designs where power supplies and amps are built on separate chassis and connected with umbilicals.

I wanted to know what type of sockets/plugs are typically used for this application (high voltage).

Ideally all of the power supply components would reside in the separate chassis including filament supplies, etc. I can imagine a plug/socket with multiple pins, maybe six to eight. I have seen a few sockets/plug combos at Partsexpress.com but these have a max of 3 connectors/pins.

Where can I source some nice plug/socket gear to build a HT umbilical with several supplies (HT, Filament, etc.. all in one umbilical)?

Thanks!
Jeff
 
#2
The connectors are one thing, but another is the cable itself. Cables with asymmetrical wire gauges (heavy gauge wire for filament, less heavy for B+, etc) do exist, but are not as common. I guess you could have multiple wires in parallel, though. Also remember that most wire is rated at 300 V. If your B+ is higher than that, you need wire rated for it.

For PCB connectors, I've found that most of them are rated at 250 V. But I figure that if I skip a pin between the high-voltage circuits and the low-voltage ones, I'd be OK... It's a hack, but it's not like I'm going into production with the amps I'm building...

Amphenol/AMP makes some nice (but spendy) multi-pin, chassis mount connectors. I've seen their style of connectors on a lot of military gear. That's probably where I'd look.

When picking a connector make sure you can't accidentally connect it the wrong way. A lot of times I find you can get the pins of two connectors to touch even if the connector isn't mated up correctly. That could be a disaster waiting to happen. And I'd have a male connector on the amp's power input - female on the cable to prevent sparks and zaps if the connector is dropped or touched when the power is on.

~Tom
 
#3
Amphenol or Bendix MIL-C series will do the job. Up to 60 pin......try Digikey or Mouser..
Cables- make your own....proper gauge and insulation, braid, flex tubing, heat shrink, - all by the yard..... THis is the way it's been done for high reliablity stuf for years and ages.
Not cheap, though... mil plugs are often in surplus though....
 
#4
The ones I have made have used whatever wire I needed, then put in a jacket of that expandable black woven mesh. I have a reel of it that I got somewhere, I can't recall, but I am sure it is readily available.

The connectors I prefer are the mil spec multi-pin types with a threaded barrel. I am not sure the voltage rating on any of them but I have never had an issue with dielectric breakdown with B+ supplies in the 450-600v range, but YMMV.
They all have great cable stress reliefs on them, which is pretty important.
All the ones I have used and seen are indexed.

I have found them and their chassis mount mates, on various surplus sites and stores.

Here are some interesting links:
Mil-Spec & Circular Connectors Listed
High Voltage Connectors (see the Rowe connectors)
https://www.fairradio.com/catalog.php?mode=view&categoryid=88
 
#5
tomchr said:
The connectors are one thing, but another is the cable itself. Cables with asymmetrical wire gauges (heavy gauge wire for filament, less heavy for B+, etc) do exist, but are not as common. I guess you could have multiple wires in parallel, though. Also remember that most wire is rated at 300 V. If your B+ is higher than that, you need wire rated for it....
~Tom
Click to expand...

Easy to make your own. Just bundle the wires together and apply heat shrink tubing over the cable and/or use flexible sleeving such as this from Newark Electronics:

Sleeving | Newark.com

As far as connectors, I would look at what AMP has in the way of circular connectors. Remember to choose the cable end that plugs into the amp with something that does not expose pins or wires.
 
#6
Loren42 said:
Remember to choose the cable end that plugs into the amp with something that does not expose pins or wires.
Click to expand...

Good point! 🙂

It is ok for the amp to have male pins on the chassis connector but definitely NOT the power supply! The best solution (but harder to source) is to have a female bulkhead connector at the power supply chassis, and a male bulkhead connector at the amp chassis. Then the cable has one male and one female connector. That way the cable end that goes the chassis (and may be hot, if the power supply is connected and powered up) is female.

That way there is never an exposed pin that has power.

By male and female, I mean the male connector has exposed pins. This is not always true, but I am using this convention for the purposes of discussion.
 
#7
Jeff,

I researched this a bit when building my last amp, and I couldn't find a nice looking solution at a price I considered reasonable. I have since seen some nice stuff at electronics surplus stores. You might call JB Saunders in Boulder, CO.

I ended up using an octal tube socket and an octal 8 pin tube base. That combo set me back around $8. For the cable, I bundled 600V rated appliance wire, wrapped it in teflon gas line tape, covered it in braid salvaged from a big old computer cable (connected to the chassis) and then covered that all in Tech Flex. I couldn't think of a nice way to cover the termination to the tube base, so I wrapped it with electrical tape. It has held up through much moving and testing, and I am not at all concerned about safety.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
 
#8
I remember an old McIntosh MI200 amp that worked on had the good old Jones connectors connecting the power supply and amplifier sections together. I think the B+ on that was close to 1000VDC. They are definitely not the best looking connectors but they are cheap and available at Mouser.

Craig
 
#9
I've used octal plugs and sockets -- this was pretty standard ham radio practice -- the octal "plug" was chassis mount on the receiving end of the transceiver. For a phono preamp I used XLR for power -- they are up to the task. for my first adcom gfp-565 I used Neutrik. heat shrink tubing by the yard can be gotten from any of the usual suspects. keeping the magnetics of a power supply for an RIAA stage is a very good idea.
 
#10
funkytek said:
Good point! 🙂
By male and female, I mean the male connector has exposed pins.
Click to expand...

This the very definition of male and female connectors....and should always be true...😛

For MIL plugs, the pins are usually inside a shroud of some sort, to protect the pins...

Tube type Octal plugs and sockets were often used on old amps and radios....but they don't give the best protection....

MIL type plugs are often sold as surplus... and unless you specifically want plugs in both ends of the cable, you really don't need to. Leave it fixed at one end,- saves one set of plug/socket.........

BTW - Jack.. what was the brand of those square multipins often used, a.o by Drake...?
 
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#16
Nikon1975 said:
So at the end you have two cables running, one for HT and the other for filaments.

D.
Click to expand...

Hi Davide,
If you would like to source your connectors in Tokyo then look for Hirose connectors,
these things are top notch and surplus ones can be found in Akihabara for decent prices.

I'm off for a few days of snowboarding, but if you're not in a hurry then I can provide more when I'm back.

Cheers,
Jeff
 
#19
I build my first amp with a separate power supply. (20 years ago)
Do you realize the powersupply is directly in the signal path? If I ever would consider this again I would make shure that the signal stays in the amplifier part and has a shortcut to ground as close to the signal tubes as possible.
Here's wat I would do: I would use a C-L-C powersupply, and put the transformers and the first C, and the L in the powersupply case. The last C would be a motorrun cap or other very good C, and that would be put in the amplifier case.
The L has high resistance to higher frequencies, and keeps the signal out of the powersupply case. The good quality C provides a way for the signal to ground.

A good friend of mine still uses a copy of the amp as I build it 20 years ago, and recently put a high quality cap in the amplifier part, and immediately he noticed an improvement of the sound quality. (not very long though, he shortcircuited some pins of the umbilical connecter... and he has a 2200uF 450v C in the powersupply case. Needless to say, he was wide awake after that. It cost him a EL34...but it is fixed now. He is happy.)
 
#20
pauldune said:
I build my first amp with a separate power supply. (20 years ago)
Do you realize the powersupply is directly in the signal path? If I ever would consider this again I would make shure that the signal stays in the amplifier part and has a shortcut to ground as close to the signal tubes as possible.
Here's wat I would do: I would use a C-L-C powersupply, and put the transformers and the first C, and the L in the powersupply case. The last C would be a motorrun cap or other very good C, and that would be put in the amplifier case.
Click to expand...

I'm using the Broskie PS-2 LM1085/10m45s powersupply, it has a 150uf cap on the output. I was planning on another cap in the amp case, thinking 50uf oil can.
 
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