Hey Greg, great looking table, beautiful plinth.
Terrific wiring solution also, shows you put some
hard work into this table!
Thanks again for the comps... means a lot!
Yeh... plenty of effort in this one to get it right.
Its an old friend (old challenge) and its a keeper.
I also had been anxious for a long time to test out
some theories to see if they'd make a positive
One of those was a wiring scheme I've had in mind
as a "fool proof" ssystem to get rid of all hum, that
might help others in the future.
Its a bit overkill, I realize, but I wanted to try it out....
and feel good that I didn't skimp or leave anything
For the power wiring, I used steel-braid sleeve
sourced from McMaster Carr covering all wiring
from the IEC plug I installed in the base to the
motorboard, the board to/from the switch, and
to/from the motor.
The wire bundle consists of:
16ga twisted pair, wrapped with foam tape, with
3rd bare-copper safety ground wire wound between
the tape and tinned copper braid-over.
This pic better shows the wiring layout
(in case it may be of help to someone)
During a pre-completion phase of assembly.
(IEC pwr jack cutout had yet to be made, and
that was done on a Bridgeport machine)
To the botom left a portion of the wire bundle
is visible, near the mounting screws for the motorboard.
(just left of motor)
The motorboard I used was the "International" board
used in the dual voltage models, which this table started
It made for a convenient solution, including mounting
provisions on bottom of top plate.
I also wanted for all the wiring to stay with the top
plate, to facillitate easy separation from the base for
ease of future maintanance.
I removed all the copper traces on the AR motorboard,
as well as all the circuitry... the switch/caps/etc. as
their configuration has only to do with the voltage
switching, and isn't helpful to this purpose.
Here's the original for comparison.
The bare board:
This is the link to my gallery page with pics from
all angles of the original board with easy viewing
of its components, for anyone needing to service
the original AR International motorboard.
https://www.vinylengine.com/phpBB2/albu ... r_id=25757
Another goal/theory I wanted to test, is grounding
the motor seperately, and isolated from the general
table grounding system.
I used the 3rd safety-ground wire in the bundle
(described above) to go ALSO to the motor housing
via a ring-lug that attaches to a motor mounting
The motor mounting screws/nuts are nylon to prevent
contact with top plate, but the lug makes good contact
with the motor housing "ear".
I also added a neoprene/nitrile-rubber dampening pad
(from Parts Express) to the motor's top, to further
isolate, both electrically and mechanically.
(in addition to the asphalt pad covering the whole top
The idea being, the motor housing, totally electrically isolated
from everything else, is "safety-grounded" via the ground
prong on the AC plug.
The seperate grounding system of the cart--> arm-->
subchasis--> top-plate are all "starred"
to one point, then on to the preamp's ground stud.
Other than keeping raw AC out of the preamp in the
unlikely event of a motor short... and shunting any
The main reason was an experiment in avoiding the
funky gounding hum-issues with these AR and AR based
tables, particularly with certain cartridge/arm combos.
The third "safety-ground" wire in the bundle throughout,
is in contact with the braid, and should provide "umbrella"
shielding even over the long length to the switch.
Also, all connections are soldered.
(except at the IEC pwr jack and motor housing ground)
On the cabling, I would wire up a pair of 45 degree
RCA plugs so yo get better clearance between the
arm and plinth.
Yeah... thats exactally what I wanted to do, but the
only one I was able to find is a very expensive Cardas
which is also so big its almost as bad as a non 45 degree
Its cable entry is also way bigger than my cable.
http://www.cardas.com/content.php?area= ... part_id=23
What I wound up doing, temporarily so as to get up
and running, was to cut down some normal high quality
RCAs at the half way point, and strip all but the inner
coating of the wires back to about 6 inches so they're
flexible enough to move easily with the subchassis.
I then covered them with shrinkwrap.
(pretty yellow and blue even :-P )
FWIW, I used this cable from navships on ebay.
Described as follows:
High quality mil. spec. wire.
4 conductors twisted of 26 AWG wires shielded
with teflon outside insulation.
Wires & shield are silver plated copper,
Conductors are each with 7 strands.
Overall OD of this wire is aprox.
0.1210 inch (3.07mm).
Capacitance is 76pf for 4ft terminated.
I covered it with a cored hiking boot lace
(from Wallmart :-) )
Switchcraft makes a nice low profile 90 degree RCA
I made up phono leads using low capacitance cable
(nothing fancy) using these right angle plugs.
Thanks so much for that info!!
If only I'd known sooner........ <sigh>
But no matter... I'll surely use those when I re-do the
Switchcraft makes very high quality connectors!
How on earth did you find them?
I googled and googled "right angle rca" and such.
Soooo... this was my "no holds barred assault"..
and it seems to have worked.
I marvel every time I listen to it.
Thanks again, and thanks to all who's knowledge and
ideas informed me!