Henry 007 wrote:
"Dennis Selwa" wrote in message
om...
Hey home brewers,
I'm looking for some nice ways to point to point wire my preamp.
I've built lots of Heathkits , Knightkits , Eicokits etc. back in the
fifties and sixties. The typical method of point to point wiring then
was to use mounting strips that had between two and six terminals
that were made of stamped out metal and phenolic.
A couple of the nicer methods I've seen was in a Mac MC60 and HK
Citation II. They used boards with terminal pins which I liked a lot.
Ok I'm looking for some nice modern ways to mount my circuitry.
Can Anyone give some sources of terminals and user friendly parts for
the home brewer?
Dennis Selwa
One thing I have learned is to use solid core cabling- much easier to bend
into shape. Whether you use silver is up to you. Tagboards are good, but
require a lot of wiring. I like a mix- some components soldered directly to
valve sockets, some on tagboards.
~h~
I am still using tagboards, and point to point, and I see no reason to use
printed boards for one off amps.
It pays to think carefully about where things are going to be laid out,
and be prepared to do some things 2 or 3 times in the interests of
neatness.
Some times I use flat boards of fibreglass, and bore 1.5mm holes to a grid
pattern
and hook the wires/component leads through, so all the R&C and the
solid wire tracks are on the same side of the board, which is bolted
12 mm above the bottom of the chassis.
This way circuits for phono stages can be wired with very short leads, less
than 10mm if possible, and it all helps to stop noise and oscillations.
I often use fine ex telephone wiring looms of all different colour coding
for preamps, but I usually select something with thicker insulation for B+
lines,
and I try to stick to a colour code for main wiring,
balck = 0V, red = B+, blue = anode, green = grid, orange = screen,
yellow = cathodes, grey = bias, purple = feedback,
pink = lower level B+, white = right channel,
yellow/white = left channel, twisted brown and blue for mains,
and heaters.
I ain't allways strict, and I vary sometimes. But in 5 years when I wanna do a
mod,
or fix something, I ned to remember WTF I did 5 years before.
for the input stages to say an integrated amp, I'll run a solid 1.6 mm solid
copper
buss wire 25mm above the tube socket underside, with wire standoffs
to hold it in place soldered to the metal tube in the centre of most 9 pin
tube sockets. This buss rail is then joined to 0V at only one point
very closs to the input socket 0V.
The chassis is also connected near this point via a 22 ohm R,
and a 0.05 ceramic cap, to stop earthy loop LF voltages
and RF from interfering in the signal path.
The chassis IS NOT used to ground any components.
You'll find many resistors can be grounded with then standing
vertically in the chassis space, from socket to 0V buss,
and thus much space is saved, and when finished
a typical circuit shouldn't look like a rat's nest, or have
leads arching over all over, allowing bending to occur,
but instead, components are stretched fairly straight between
connecting points, so they cannot be swayed to touch other components.
Careful dressing of leads is nice, and looping wiring carefully to allow access
in future with
a soldering iron, and wires where stray capacitance effects is important should
not
be laced together, but thuse where it isn't important, should be laced,
or tied with cable ties.
Large caps should be glued to the chassis with silicone
sealant. You don't want vibration to fatigue the wiring.
And hot parts, such as wire wound R should be located in a breeze,
and not up against caps.
I could go on, and on, but decent tube craft was employed in many old
oscilliscopes,
scientific gear, and such levels of craft are never found in old radios, and
consumer grade
electronics.
If you want to see good tube wiring, look into old good gear.
Printed circuit boards like used in ARC and CJ amps, with heavy tracks and
mil spec boards don't sound any better than the well done DIY wire up.
It is pointless trying to copy this type of construction, and any mods, along
with repairs
can be a nightmare.
Patrick Turner.
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