A Belt-Drive Turntable Upgrade
Tube, Solid State,
Loudspeaker Technology
Article prepared for www.audioXpress.com
A Belt-Drive Turntable Upgrade
By Gary Galo, Regular Contributor
Give your turntable a new lease on life with these tonearm re-wiring tips.
B
ack in the mid-1980s, I published
three articles in this magazine’s
predecessor describing a beltdriven turntable based on the old
AR-XA drive system. The first part described a new base for the turntable, and
modifications to the original AR-XA
sub-chassis to reduce resonance problems
and accommodate the Mayware Formula
4 and Grace 747 tonearms1. The second
installment described an electronic speed
control designed to provide a low-distortion sine wave to the turntable motor.
A variable-frequency oscillator allowed
pitch adjustment on synchronous motor
turntables, and 45 rpm speed without
moving the belt to the larger pulley2.
The third part involved replacement
of the modified AR sub-chassis with
Merrill Audio’s acrylic sub-chassis, and
the installation of Joseph Grado’s now
legendary Signature ToneArm3. Other
enhancements included a high-torque
Merrill synchronous motor, the Merrill
replacement spindle, Merrill lead coating
for the outer platter, Merrill platter balancing, heavier springs for the sub-chassis, and hum shielding necessary in order
to use the turntable with the unshielded
Grado Signature 10MR phono cartridge.
This excellent cartridge was subsequently
upgraded to the outstanding Grado Signature XTZII. The third article included
a sidebar by George Merrill on sub-chassis design and hum shielding. All three
articles have been reprinted in The LP is
Back!4
Although I own over 6000 CDs, I
continue to buy and play LPs, and am
still actively interested in analog playback (including a large collection of 78
rpm records). The Galo/Merrill/Grado
turntable has served me well for about 20
years, but it was time to either replace the
stylus in my Grado XTZII or buy a new
cartridge. After John Grado informed me
that the XTZII stylus was still available,
I decided to obtain a replacement rather
than purchase a new cartridge ( John is
the nephew of Joseph Grado and the
President of Grado Laboratories).
The XTZII, like the other Grado cartridges, is a moving iron design, and its
low coil inductance and resistance (9mH;
70Ω), plus an ultra-efficient generator
system, provides many of the advantages
of moving coil designs without some
of the liabilities. The Grado Signature
ToneArm remains a stellar performer,
and an ideal match for the Grado cartridges. We fortunate few were able to
purchase one in the mid 1980s—during
the short time it was available—for the
bargain price of $485. If you’re looking
for a new cartridge, Grado has a full line
covering all price ranges. You can order
Grado cartridges and replacement stylii
from Audio Advisor, Needle Doctor, and
LP Gear.
SUSPENSION ISSUES
One problem with belt-driven turntables
using three-spring suspensions concerns
the tonearm interconnect cable. It’s dif-
ficult to dress the tonearm cable in a way
that doesn’t interfere with the turntable
suspension. In “The Belt-Driven Turntable Revisited,” I suggested fastening the
Grado cable to the underside of the turntable, on the end opposite the tonearm.
I also provided plans for constructing
a rectangular “sub-base,” which raised
the turntable to allow the cable to droop
without pulling on the turntable suspension or touching the surface below.
Though this system worked adequately,
it has always been rather cumbersome.
But, the Grado tonearm cable was heavy
enough that I really didn’t have much
choice (Grado used a Mogami Neglex
2534-style balanced quad cable, but Joe
Grado told me that the copper was slowdrawn to his specifications).
Grado’s tonearm cable was a fine performer in 1985, but there are many superior cables available today. My favorite
interconnect is D.H. Labs’ Air Matrix
cable fitted with their RCA-HC Ultimate RCA Plugs. Like many highperformance interconnects, this cable is
much too heavy to be connected directly
to a tonearm, so I decided on a two-stage
approach to the problem.
Cardas makes a 5-pin DIN-style tonearm base connector and a 4-conductor,
33 AWG shielded tonearm interconnect that is thin and extremely flexible.
I use the Cardas interconnect to link
the 5-pin tonearm connector to a pair of
D.H. Labs CM-R1 RCA jacks mounted
on the rear of the turntable base. The
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Cardas wire has no effect on the turntable suspension. You can then use the
interconnect of your choice—no matter
how stiff or heavy—between the RCA
jacks and your preamp’s phono input.
Although my instructions are tailored to
the Galo/Merrill/Grado turntable, this
approach is suitable for many other turntable designs, with and without a springsuspended sub-chassis.
CONNECTOR PLATE
I mounted the new RCA jacks and
ground posts on a brass plate, cut from
a piece of 2″ wide brass stock, which I
purchased in the hobby section of my
local hardware store (Photo 1). Cut the
brass stock 5 3/8″ long and drill the plate
for the two RCA jacks (a 3/8″ hole is
just right for the insulating washers supplied with the D.H. Labs jacks), two
ground posts, plus a hole for a 4-40
machine screw, which will hold a nylon
cable clamp between the two RCA jacks.
You should also drill five mounting holes
5/16″ from the edge of the plate.
Mount the connectors and ground
posts as shown in Photos 1 and 2. The
ground posts are made with 6-32 × 5/8″
machine screws, #6 ground lugs, lock
washers, hex nuts, and knurled thumbnuts. One ground post should be insulated from the brass with a nylon shoulder washer and nylon flat washer and
mounted closest to the RCA jacks. The
remaining ground post should make electrical contact with the brass plate.
Prepare a 12″ length of the Cardas
tonearm cable by stripping about 1½″
of the outer insulation from one end
and about ¾″ from the other. Carefully
unravel the braided shield on each end,
twist the strands together, and tin the
ends. The Cardas center conductors are
grouped into two twisted pairs. Carefully strip ¼″ of the Teflon insulation
from the end of each conductor, twist
the fine strands together, and tin them.
PHOTO 1: The assembled connector plate. New RCA jacks and ground posts are
mounted on a piece of 2″ brass stock. The ground post closest to the RCA jacks is
insulated from the brass plate.
PHOTO 2: The connector plate mounted on the rear of the turntable base. Nearly any interconnect cable, no matter how heavy, can be used to connect the turntable to the preamp.
2 audioXpress 2008
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Make the white/blue pair left signal and
ground, and red/green pair right signal
and ground.
Figure 1 is the wiring diagram. Solder
the end of the Cardas cable—with ¾″ of
insulation removed—to the Cardas DIN
Phono Connector (the view in Fig. 1 is
facing the solder terminals on the Cardas
connector). Solder the other end of the
Cardas cable to the connector plate assembly. The shield should be soldered to
the ground post that is insulated from
the brass plate. Use a short length of
heat-shrink tubing over the shield, and
another short piece over the entire cable.
Make sure that the cable clamp holds the
cable firmly in place, and that there is
no strain on the thin center conductors.
After you’ve finished, use an ohmmeter to verify that the signal and ground
connections match those of the original
Grado tonearm cable.
DISASSEMBLY
You must disassemble the turntable in
order to install the new tonearm wiring.
Remove the outer platter, the belt, the
counterweights, and head shell from the
Grado tonearm. Then, remove the arm
from its base, using the Grado instruction booklet as a guide (you don’t need
to remove the Grado arm base; it can remain fastened to the Merrill sub-chassis).
Remove the inner platter and wipe any
oil remaining on the spindle with a soft,
lint-free cloth. Store in a safe place. Disconnect the Merrill sub-chassis ground
wire from the motor mounting bolt and
remove the sub-chassis. Keep the subchassis upright so you don’t spill any oil
from the spindle well, and store the subchassis in a safe place, covering the spindle hole to keep out dirt.
As you face the rear of the turntable,
the left edge of the brass plate will be 1
7/8″ from the edge of the oak turntable
base (Photo 2). Remove the rear piece
of aluminum angle stock that supports
the top plate assembly (Photo 3). Make
a rectangular cutout—about 1 3/8″ × 4
1/8″—in the back of the turntable base
(Photo 4). Cut the aluminum angle piece
so it doesn’t extend beyond the rectangular cutout, and re-install. Include a 1/8″
cable clamp as shown in Photo 3.
Drill pilot holes for mounting the assembled brass plate, and mount with five
#6 × 5/8″ brass wood screws. Mount
FIGURE 1: Wiring diagram for the belt-driven turntable upgrade. Separate chassis and
signal ground posts accommodate a variety of installation requirements.
another 1/8″ nylon cable clamp for cable
support, as shown in Photo 3. The cable
should be able to slide in this clamp, allowing you to adjust the position of the
cable as needed.
Temporarily secure the Cardas DIN
connector to the sub-chassis suspension
bolt with a nylon cable tie, to prevent strain
on the cable and connector. Connect an
PHOTO 3: Bottom view of the turntable
base with the new connector plate installed. The rear aluminum angle bracket
is shortened to make room for the connector plate cutout.
18 AWG ground wire from the motor
mounting bolt to the ground post closest
to the edge of the brass plate. Route this
ground wire through the first cable clamp.
Use a #6 ground lug on the end connected
to the motor mounting bolt.
BRASS CONES
With the new tonearm wiring arrangement, the turntable no longer needs the
old sub base. You can re-use the old rubber feet of the main turntable base, but
I prefer to replace them with something
more effective at dissipating energy away
from the turntable. A variety of suitable
metal cones are available, including some
that are rather exotic and expensive.
Parts Express carries its own Dayton brand of isolation cones that work
very well, and a package of four costs
only $25. The cone itself is a two-piece,
threaded arrangement that is heightadjustable, which is handy for turntable
leveling. The cones come with flat receptacles, which prevent the sharp points
from damaging the surface below, and
are available in either gold or chrome
(gold is a better match for my oak turntable base).
The cones are also supplied with eight
adhesive foam cushions, but I prefer to
secure them with a very thin drop of silicone glue. I mounted the cones just inside the old rubber feet, as shown in the
photos, because this was the best position
for the top shelf on my equipment rack
(I left the old rubber feet in place). If
your turntable shelf is large enough, you
can remove the rubber feet and install
the cones in the four corners.
Long-time readers will note that I no
longer use the turntable isolation shelf
that I described back in TAA 1/875. We
moved to a new house in Sept. 2005, and
my downstairs listening room has a concrete floor, so I have no need for it. If you
have an unstable floor, I still recommend
using some type of wall-mounted shelf.
After the brass cones are in position,
let the weight of the turntable base hold
them in place for 24 hours to allow the
silicone glue to fully cure. Use the leveling feature of the cones to ensure that
equal pressure is applied to all four. I
also glued the receptacles to the shelf
on my equipment rack. Use as little silicone glue as possible (the tiniest dab will
PHOTO 4: Rear view of the turntable base, showing the cutout and pilot holes for mounting the connector plate.
audioXpress 2008 3
be enough to hold the cones firmly in
place), to avoid having a reactive coupling of the turntable to the cones and
the shelf below.
REASSEMBLY
Remove the cable tie temporarily holding
the Cardas connector to the sub-chassis
mounting bolt. During reassembly, take
care not to strain the cable and connector.
Reassemble the turntable following the
directions in “The Belt-Driven Turntable Revisited.” Be sure to reconnect the
ground wire from the Merrill sub-chassis
to the motor mounting bolt.
You may need to add a small amount
of Merrill Ultra High-Film Strength
Turntable Oil to the spindle well (this
is the oil originally supplied with the
Merrill sub-chassis). Fortunately, George
Merrill still has this oil in stock, if you
need more. Contact him at George Merrill’s Analog Emporium, or try MerrillScillia Research.
AR-XA drive belts stretch out over
time and eventually need replacement.
The best source is A-B Tech Services,
a company supplying parts for old AR
loudspeakers and turntables. The company is run by Alex Barsotti, a long-time
employee of Acoustic Research. A-B
Tech’s parts are manufactured to original
specifications, and are often less expensive than the substitutes sold by other
dealers.
Replacement belts normally have a
powdery white coating of talc already applied. If yours doesn’t, be sure to talc the
belt before re-installing, using pure talc,
not talcum powder.
After you reinstall the Grado tonearm,
plug the Cardas connector into the base
of the arm. It will be a tight fit. The Cardas cable will form a small loop under
the tonearm. Adjust the position of the
Cardas cable in the cable clamp as needed. Follow the original Grado Signature
ToneArm setup instructions to the letter.
Once you have re-assembled the turntable, connect it to your preamp with
your choice of interconnect cables. As
mentioned, I am extremely pleased with
the performance of D.H. Labs’ Air Matrix Interconnect Cables fitted with their
RCA-HC Ultimate RCA Plugs, which
you can buy from Audio Concepts, the
well-known loudspeaker manufacturer.
The Air Matrix cables are not sold in
bulk form—only pre-assembled.
For those who wish to assemble their
own interconnects, I recommend D.H.
Labs’ Pro Studio Interconnect Cable,
plus the RCA-HC Ultimate RCA Plugs,
both available from Parts Connexion.
Parts Connexion also carries a D.H. Labs
cable custom-manufactured for them, the
BL-Ag, which consists of 23 AWG solid-core silver center conductors, a foamed
Teflon tape-wrapped dielectric, plus a
foil shield and drain wire. I have not tried
it, but it’s certainly worth investigating.
The BL-Ag is too small for the Ultimate
RCA Plugs—D.H. Labs recommends
its RCA-2C for this cable. For a costeffective solution, D.H. Labs’ BL-1 fitted
with RCA-2C connectors is still hard to
beat for the money.
Normally, I recommend putting a
jumper between the two ground posts,
and running a single ground wire to the
preamp. Make the ground and jumper
wires with 18 AWG stranded, insulated
wire and crimp-on spade connectors. My
system is silent using this grounding arrangement.
However, some preamps or integrated
amplifiers may yield lowest noise with
separate ground wires from the tonearm
and the turntable chassis ground posts.
The two-ground post arrangement allows maximum flexibility for a variety of
installation requirements.
The upgraded turntable is shown in
Photo 5 . The number of high-priced
turntables on the market continues to
amaze me, with some stretching well into
the five-figure range. With the tonearm
4 audioXpress 2008
wiring upgrade, and a new stylus or cartridge, the Galo/Merrill/Grado turntable
should continue to provide musically satisfying sound from your vinyl collection
for years to come, without breaking your
aX
bank account.
REFERENCES
1. Galo, Gary, “AR System Drives New Turntable,” Audio Amateur, 3/85, pp. 27-38.
2. Galo, Gary, “An Electronic Speed Control,”
Audio Amateur, 1/86, pp. 7-13.
3. Galo, Gary, “The Belt-Driven Turntable Revisited,” Audio Amateur, 3/88, pp. 24-30 (including
the sidebar “Sub-chassis Design and Hum Shielding Considerations” by George Merrill).
4. The LP Is Back! Peterborough, NH, Audio
Amateur Press, 1999 (available f rom www.
audioxpress.com).
5. Galo, Gary, “A Turntable Isolation Shelf,”
Audio Amateur, 1/87, pp. 45-47 (Not reprinted in
The LP Is Back!).
VENDORS
Grado Laboratories
4614 Seventh Ave.
Brooklyn, NY 11220
(718) 435-5340
www.gradolabs.com
[email protected]
Audio Advisor
3427 Kraft Ave., S.E.
Grand Rapids, MI 49512
1-800-942-0220
www.audioadvisor.com
Needle Doctor
419 14th Ave., SE
PHOTO 5: The upgraded belt-driven turntable. Dayton adjustable brass cones replace the
old turntable sub-base.
www.audioXpress .com
Minneapolis, MN 55414
800-229-0644 (orders only)
612-378-0543
www.needledoctor.com
[email protected]
LP Gear
2227 Double Tree Ave.
Henderson, NV 89052
www.lpgear.com
[email protected]
D.H. Labs
9638 NW 153rd Terrace Alachua, FL 32615
386-418-0560
www.silversonic.com
[email protected]
Parts Connexion
2885 Sherwood Heights Drive
Unit #72
Oakville, Ontario
Canada L6J 7H1
1-866-681-9602
www.partsconnexion.com
[email protected]
Audio Concepts, Inc.
PO Box 26
Onalaska, WI 54650
608-786-4729 www.audioc.com
[email protected]
www.partsexpress.com
[email protected]
Mouser Electronics
1000 North Main Street
Mansfield, TX 76063
800-346-8673
www.mouser.com
[email protected]
George Merrill’s Analog Emporium
820 Herbert Rd. #109
Cordova TN 38018
901-751-3337
www.gmanalog.com
[email protected]
Merrill-Scillia Research, LLC
PO Box 539
North Branford, CT 06471
901-619-3322
www.merrillaudio.com
[email protected]
A-B Tech Services
800-225-9847
www.abtechservices.com
[email protected]
Parts Express
725 Pleasant Valley Dr.
Springboro, OH 45066
800-338-0531
(1)piece 0.064″ thick brass stock, 2″ wide × 5 3/8″ long, K&S Engineering #14121-10249 or equivalent (local hardware store or hobby shop)
Cardas SDIN, 5-pin DIN tonearm connector, straight (Parts Connexion #53481)
Cardas 4 × 33 AWG tonearm wire with shield, 12″ (Parts Connexion #64312)
(1)pair DH Silver Sonic CM-R1 chassis RCA jack (Parts Connexion #68098)
(2) each 6/32 × 5/8″ machine screws, lock washers, nuts and knurled thumbnuts (local hardware store)
(1) each nylon shoulder washer and flat washer (local hardware store)
(3) #6 ground lugs (Mouser #534-7312)
(3) 1/8″ polypropylene cable clamps (Radio Shack #64-3028)
(5) #6 × 5/8″ brass wood screws (local hardware store)
1/8″ heat-shrink tubing (Radio Shack #278-1627)
Dayton ISO-4G (gold) or ISO-4C (chrome) Isolation Cones (Parts Express 240-720 or 240-721)
D.H. Labs Air Matrix Interconnect Cables (Audio Concepts)
or
D.H. Labs Pro Studio bulk interconnect cable (Parts Connexion #64786 or Audio Concepts) and RCA-HC Ultimate RCA
Plugs (Parts Connexion #64434 or Audio Concepts)
or
D.H. Labs BL-Ag bulk interconnect cable (Parts Connexion #66070) and RCA-2C RCA Plugs (Audio Concepts)
or
D. H. Labs BL-1 interconnect cable (Audio Concepts) and RCA-2C RCA Plugs (Audio Concepts)
Miscellaneous: 18AWG ground wire; crimp-on spade connectors (Radio Shack #278-1220 & #64-3124)
audioXpress June 2005 5
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