Show off your AR XA tables

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pivot
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Post by pivot » 17 Jun 2009 19:34

MuZak wrote:Actually, I've been thinking of PMing you to ask some
things about the SME.
Specifically about arm cabling, and how you delt with
the fact that the arm RCAs are so close to the base corner.
Switchcraft makes a nice low profile 90 degree RCA connector, SW3502RABAU.

Available here:

http://www.audiogear.com/cgi-bin/shoppe ... add=action

I made up phono leads using low capacitance cable (nothing fancy) using these right angle plugs.

MuZak

Post by MuZak » 24 Jun 2009 05:12

Hey Greg, great looking table, beautiful plinth.
Terrific wiring solution also, shows you put some
hard work into this table!
Hey Steve...
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
difference.

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
aside.

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.

8792
8793
9985
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.

8794
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
out as.
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.

9122
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.
8788
The bare board:
8852

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
screw.
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
plate's bottom)

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
dangerous voltage...
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
plug.
Its cable entry is also way bigger than my cable.
http://www.cardas.com/images/oem/MALE_RCAS/GRNO.JPG
http://www.cardas.com/images/oem/JPEG_DRAWINGS/GRNO.jpg
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.
8491
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.
(19pf /ft)

I covered it with a cored hiking boot lace
(from Wallmart :-) )
------------------------------------

Hey Kevin..
Switchcraft makes a nice low profile 90 degree RCA
connector, SW3502RABAU.

Available here:

http://www.audiogear.com/cgi-b.....add=action

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
cable!!
Switchcraft makes very high quality connectors!
Thanks again!
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!

fscott
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Location: USA - Oh

Post by fscott » 27 Jun 2009 02:59

I can finally say I'm done with my XA. New caps, new cart, new base, new RCA jacks, everything cleaned, polished, lubed, and oh so quiet! What a great TT AR made!

http://www.flatpick-l.org/tonytab/ar15.jpg
http://www.flatpick-l.org/tonytab/ar16.jpg

solex
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Location: New York

Post by solex » 01 Jul 2009 02:24

looks great fscott you paint work looks great did you go with the hammerite?. Let's see some pictures underneath and from behind... :lol:

MuZak

Post by MuZak » 01 Jul 2009 22:45

Wowww!
Stunning!
Congrats!!

Plz do post more pix.
Also, details on the armrest plz.

danieldust
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Location: Northeast Florida

Post by danieldust » 02 Jul 2009 03:28

Hi all!

I'm geting the warm fuzzies looking at all the beautiful AR XAs that have been posted on here lately. Keep up the good work!

MuZak

Post by MuZak » 02 Jul 2009 06:29

Hey Scott! WB!
Hope all went well with your move.

Did you notice what I wrote about my grounding scheme?
Thats kinda what I was trying to describe to you
awhile back.

Also, how do ya like what I did with the International
(dual voltage) motor board?
You're the only other owner that I know of that has
(had) it.

Btw.. I used the same color hammerite that you
did (if I recall correctly).

danieldust
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Post by danieldust » 04 Jul 2009 03:27

Hi Greg. Interesting about all the steps you took to ensure proper grounding. Most of your description is over my head though. How does it work?

I am pretty convinced there is nothing I can do to eliminate my RFI issues short of moving away from the Radio station that's down the street. I just grin and bear it for now.

xmas111
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Post by xmas111 » 20 Jul 2009 01:00

Just finished rebuilding this baby....nice and plain!

New motor, rewired tonearm, etc. I'm putting together a webpage with lots of pictures of the rebuilding. Should have it up later this week.

http://johnsweather.com/ar%20turntable.JPG

pbda
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Location: London, England

Post by pbda » 29 Jul 2009 16:27

xmas111 wrote:Just finished rebuilding this baby....nice and plain!

New motor, rewired tonearm, etc. I'm putting together a webpage with lots of pictures of the rebuilding. Should have it up later this week.
Gorgeous.

solex
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Location: New York

Post by solex » 29 Jul 2009 21:48

Agreed, looks great, nice authentic restoration...

snfrosten
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Post by snfrosten » 30 Jul 2009 00:15

Yes, great stock looking table with a beautiful wood plinth, love the grain in the wood :)

John111
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Joined: 20 Jun 2009 11:18
Location: massachusetts

Post by John111 » 30 Jul 2009 00:34

pbda wrote:
xmas111 wrote:Just finished rebuilding this baby....nice and plain!

New motor, rewired tonearm, etc. I'm putting together a webpage with lots of pictures of the rebuilding. Should have it up later this week.
Gorgeous.
Thanks!

I finally finished the webpage on rebuilding the AR XA.

I didn't go into every little detail but I hope it helps someone who might think about getting one these great turntable.

here's the link....
http://johnsweather.com/Turntable.html

John

fscl
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Post by fscl » 30 Jul 2009 16:21

Thanks for the link, I've got it bookmarked.

I'm going to have to break open my hermetically sealed cabinet holding my XB and update / refirb soon. My original dust cover is cracked. Any tips?

Thanks for the inspiration.

Fred

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Location: Hays County, Texas, USA

Thirtyeight years later...

Post by pmsummer » 10 Sep 2009 01:07

...I've finally got an XA again.

http://img228.imageshack.us/img228/5482/p9080001h.jpg

http://img80.imageshack.us/img80/6251/p9060003.jpg

It's a late model (vinyl base), but in great shape (as soon as I trace down the dead channel cause... the usual suspects not yet confirmed).

I'm keeping my eye's peeled for a wood plinth. But boy O boy does this bring back gret memories!

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