I'm trying to decide on that age old question of what connection to
make from seperate PSU chassis to main valve amplifier chassis. I'm
thinking in terms of a shared PSU and two monobloks, so connectors
would only have to take the power to one amp. Criteria I decided were
essential we
a) low cost (so no Amphenol connectors)
b) potentially large number of pins (at least 15)
c) locking (so can't get pulled out by accident)
d) at least one connector must safely take 360Vdc (equals 250v AC
rating). Possibly the option of two.
e) common part, not likely to become obsolete

first I agonised over one cable or two, and decided one cable would
require too high density, be hard to wire, would be expensive, and
would be an uncommon part. Amphenol out the window.

next I did the calculations for number of connectors. Since I'm
planning for three stages of DHTs and my system is balanced, this is
what I found:
* 12 connections for the filaments of 6DHTs.
* earth
* -15vDC for CCS
* one B+ or maybe two.

that's a minimum of 15 connections. So my eye fell on D connectors.
Relatively easy to wire up and available in 15 way which is nicely
compact. Some are rated at 500v even, so a single 15 way D connector is
not impossible.
but while I was happy with the filaments and the -15v supply on D
connectors, I would really like better contacts for B+ and earth. My
two choices for an added connector we
a) speakon plugs in 2,4,8 way
b) XLRs
Speakons are cheap in four way but expensive in 8 way, so 4 way remains
a possibility. I'm not quite eliminating them but I'm a bit put off by
the following:
1) they're bigger and stick out more than XLRs
2) some idiot might plug a speaker into the PSU box

So XLRs. they offer the possibility of using 4,5,6 or 7 way. Now, I
spoke to Neutrik about the voltage rating for these, and it's a bit
more complex than you think. Some of their paperwork specifies 50v for
the whole range, some specify 150v, some specify different voltages for
different connectors. The sales guy in the UK quoted me 250vAC for 3-6
way and 125VAC for the 7 way. Not much agreement here, and the
unbranded Chinese ones have no voltage rating. In terms of availability
the 5 ways are common, 7 quite rare and gets eliminated because won't
handle the voltage. Four and six way are more unusual, and six way is
much more expensive. Four way can be had in cheap unbranded. So I'm
thinking 4 way right now, with the 15 way D connector, because this
gives the biggest pins and widest spacing so with unbranded the chances
are they're OK for 250vDC, or at least more likely to be than the 5
way.

I hope you've followed all this. So any suggestions? Anything I've left
out like BNC for just the B+ (high voltage)? Never used BNC but it's
locking at least. Is my above reasoning reasonable? Bright ideas?
Andy