Radial Engineering Stealth One Guide de l'utilisateur
Radial Audio Stealth One – Setup Manual
This manual addresses the setup of the Stealth One on your turntable. Refer to the Owner manual for
day-to-day care and maintenance of the Stealth One.
Congratulations!
You have purchased the finest tone arm in the world. The Stealth One is a precision electro-mechanical
device. It plays vinyl recordings in the same manner in which the recording was originally cut on the
mastering lathe, in a straight line.
T
he
Stealth
One
completely eliminates “skating” forces during
mastering lathe, in a straight line.
T
he
Stealth
One
completely eliminates “skating” forces during
playback, along with the tracking errors present in all pivoted arms. With normal care and minimal
maintenance, the Stealth One will bring you consistent imaging and accurate sound reproduction from
the outermost groove to the innermost groove of every vinyl record. Since the arm is unlike pivoted
arms, you are strongly advised to read these instructions thoroughly before beginning installation.
Unpacking Instructions
Follow these steps:
1. Grasp the Plexiglas channel with one hand, and steady the shipping container with the other
hand. Gently pull both the arm and the attached two foam end panels entirely out of the
shipping container. Set on a smooth, uncluttered workspace.
2. Remove the two foam end blocks, and replace them in the shipping carton.
3.
Remove the accessories box from the shipping carton, and place
it
on the workspace.
3.
Remove the accessories box from the shipping carton, and place
it
on the workspace.
4. The tone arm is mounted upon a 12”x2.5”x3/8” thick black Plexiglas base plate. The arm and
base plate are held together by four Neodymium magnets (visible from the bottom of the base
plate at the four corners, where the front and back elevator towers meet the base plate).
5. The next page provides a complete listing and photos of the accessories provided. The
accessories list shows the quantity of the items and the installation step in which the accessory
is used (steps A to F). Please review the list and find the picture of the accessory below the list.
Some of the accessories are provided to assist in the initial setup of the arm on your turntable.
Select those accessories now (step A), and set the other accessories aside for midstream or
optional installation later.
6. Please contact Radial Audio if any accessories are not present, or need to be replaced in the
future.
1
Accessories Inventory: (quantity),(install step A to F), description
1. (1)(A) Base Plate shipping block, and 5mm “L”-shaped hex wrench.
2. (1)(A) Stylus overhang setup protractor: Plexiglas center hole with engraved line.
3. (1)(A) 5 volt AC adapter: power supply for the Stealth One.
4. (1)(B) Counterweight, counterweight rod, two blue knurled locking nuts, 5mm “L” wrench.
5. (2)(B) Wands: one higher mass (medallions), one lower mass (ladder), finger lifts.
6. (2)(B) Cartridge mounting pads: one pre-mounted in each wand.
7.
(1)
(B)
C
artridge “simulator” block, for verifying
cartridge
verticality
.
7.
(1)
(B)
C
artridge “simulator” block, for verifying
cartridge
verticality
.
8. (10)(B) M2.5 x 1” nylon screws, Philips head: for cartridge mounting, straight Razor blade,
microfiber cloth, small Philips head screw driver.
9. (1)(C) Stylus overhang adjustment tool: Blue knurled nut mounted on a threaded rod; M2 hex
“L” shaped hex wrench: sets depth stop inside the cartridge mounting pad.
10. (2)(D) Elevator adjustment knob: round black knurled knob with hex socket at bottom.
11. (2)(E) Stylus spotlights: curved LED’s, one bright white, one warm white spectrum.
12. (1)(F) Vial of damping and/or mass adjusting lavender “silly putty”-like viscous material.
13. (0) base plate shims,
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Tone Arm/Turntable Setup
Since Radial Audio does not manufacture a matching turntable for the Stealth One arm, these setup
examples present general approaches to the “unknown” partner.
It would be best to start the process on a quiet day, allocated for just this activity. This is an iterative
process, as the best alignment position of the tone arm on the turntable in try and retry.
Having done the setup and alignment on various turntables capable of hosting the Stealth One (but not
all), what follows are some techniques that you can
evaluate and adapt to your turntable.
all), what follows are some techniques that you can
evaluate and adapt to your turntable.
Since most turntable arm mounting boards are intended for a pivoted arm, there may already be a pre-
drilled hole where a pivoted arm would be fastened. Ignore the hole.
Review the turntable’s physical design to find a straight surface that can be used as a 90 degree
reference from the center spindle. The best reference would be a plinth cast with a straight body on the
turntable’s right-hand side. Failing that, then look for a straight surface on the exterior of the
turntable’s frame. Right side is best, but it’s possible to extrapolate a 90 degree line from a straight
front or rear turntable frame.
Turntables that are “organic” in design may still be conquered, but with more ingenuity required. If the
turntable resembles an unidentified flying object, it might be best to opt for a more standard design.
The only absolute requirement is that the mounting surface for the tone arm be flat, and parallel to the
turntable
’s p
latter
surface.
The mounting surface should be continuous, not a ledge where the tone arm
turntable
’s p
latter
surface.
The mounting surface should be continuous, not a ledge where the tone arm
would extend out without support below.
Setup Overview: (General Objectives 1 to 5):
1. Setup tone arm base plate parallel to an imaginary line emanating from the turntable’s center
spindle outward to the edge of the turntable platter.
2. Mount cartridge in wand and adjust stylus overhang.
3. Setup tone arm and tone arm base at a vertical height where the wand and cartridge is parallel
to the platter surface.
4. Setup tone arm displacement to the front of the platter so that cuing (dropping the stylus under
control of the lift/lower motor) results in the stylus making contact within the lead-in groove
area, safely inside the 12” vinyl record perimeter (lip).
5. NOTE: Objectives 3 and 4 can be done together in multiple iterations, gradually achieving the
end result.
They are explained separately for clarity
.
3
end result.
They are explained separately for clarity
.
Setup Objective 1: Aligning the tone arm base plate 90 degrees to the center spindle
Standard method: The first tool needed is in the accessories, a stylus alignment “protractor” with a hole
and a straight line running from the center hole to the edge. Use tape or shims to immobilize the platter
to the plinth. Place this tool on the platter and approximate 90 degrees in relation to the future tone
arm base plate location. To get an exact 90 degree tool position, use a carpenter’s square and a flat
“board” or “sheet” to reference some straight surface on the turntable’s frame. Now position the tool
at 90 degrees, and use tape to immobilize the tool to the platter.
Don’t want to use the stylus alignment protractor?
Don’t want to use the stylus alignment protractor?
Alternate method: not using the accessory. Using a white vinyl LP and a fine Sharpie pen, draw a fine
black line on the LP, perpendicular to the center spindle (white vinyl LP now drafted as an alignment
tool). Notice that the carpenter’s square is being referenced from the front of the turntable plinth, by
association with a flat sheet of Plexiglas. Not in the photo is a parallel wooden offset whose thickness
equals half the diameter of the center spindle (9/32”, .28125”, 7.3mm). Sharpie line was drawn when
the wooden offset was in place.
4
Example 1: Rectangular Plinth
Setup is more straightforward if the plinth is rectangular, or has a straight surface that can be used as a
90 degree reference and constant distance from the center spindle.
In this example we have a rectangular plinth with a totally flat surface, meaning that the plinth has no
ridge to butt the tone arm base plate against.
So, to utilize the plinth’s rectangular form, position the Stealth One with base plate only (no arm) and
“eyeball
”
it
parallel
to
the turntable plinth
’s right
-
hand edge. Place the scribed line white LP on
the
“eyeball
”
it
parallel
to
the turntable plinth
’s right
-
hand edge. Place the scribed line white LP on
the
platter. Iteratively, adjust the tone arm base plate’s “eyeball” position by zeroing in on the stylus
overhang scribe line on the white LP, as below:
5
This process gets close to the final tone arm base plate position. Leave the tone arm base plate in place
and grab some strapping tape.
Place two lengths of strapping tape exactly adjacent to the tone arm base plate. This is a “ballpark”
reference marking, which will be improved upon.
Use a depth gauge, or a digital calipers (this example) with a depth extension rod. First, measure near
the front of the turntable plinth (left below), and then near the rear of the turntable plinth (right below):
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On the tone arm base plate, locate the four mounting holes (with a slotted sliding depression between
each pair). Use a sharp pointed compass needle to scratch the outer rim of the four mounting holes on
the turntable plinth’s bottom. Center drill the four mounting holes into the turntable’s plinth.
Example 2: Custom turntable mounting board:
You may prefer to have a custom Stealth One mounting board for your turntable.
This example relates how a custom Linn Sondek LP-12/Stealth One mounting board was developed.
Hopefully, this process demonstrates certain techniques you may find useful.
Remove the Linn Sondek LP-12 supplied board.
Create a new mounting board from material of your choice, but make the rectangular dimensions the
Create a new mounting board from material of your choice, but make the rectangular dimensions the
same as the original Linn Sondek mounting board. Except,the plate is 2mm thicker than the original.
Position the custom tone arm mounting board squarely equidistant against the inside of both the right-
hand and left-hand sides of the Linn Sondek’s wooden frame. Several parallel wooden slats of constant
thickness are used to maintain equal distance within the turntable frame’s mounting board void area.
With the wood slats tightly in place: On the custom mounting board’s underside, mark the position of
the three original Linn Sondek mounting board holes (using a sharp metal point, like a compass center).
The three underside holes are drilled on center, and then hand-tapped for 3mm screws.
Fasten the custom mounting board to the Linn Sondek’s plinth mounting board extensions, while the
parallel wood spacers are still in place. Finally, remove the parallel wooden spacers. The mounting
board appears to float with an equal mote on all four sides. This process transfers the square accuracy
of the Linn Sondek’s wooden frame to the custom moun
ting board’s position.
of the Linn Sondek’s wooden frame to the custom moun
ting board’s position.
Sometimes, it is just more direct to replace the manufacturer’s tone arm mounting board with a board
that is a perfect interface between the Stealth One and the turntable. See photo on next page.
Notice the four Neodymium magnets embedded in the custom mounting board. These magnets are
aligned with four corresponding magnets on the bottom of the Stealth One base plate. To drop the
Stealth One onto this custom mounting board, simply position the Stealth One base plate approximately
along the base plate scribe lines in the custom mounting board (look hard, some can be seen).
The Stealth One base plate will “snap” into a magnetically “locked” alignment. No need for mounting
screws between the tone arm base plate and the custom turntable mounting board.
The standard Linn mounting board is 10mm thick.
The cus
tom replacement is a 12mm thick
black
7
The standard Linn mounting board is 10mm thick.
The cus
tom replacement is a 12mm thick
black
Plexiglas sheet, beveled 2mm all around on the top surface. The extra 2mm thickness assures that the
tone arm will not bottom out on the Linn Sondek LP-12 turntable frame, as the tone arm base overhangs
the frame slightly in the front.
This custom Plexiglas mounting board is available from Radial Audio as a special order.
Above: custom Linn Sondek LP-12 tone arm mounting board using magnets for alignment and hold
down.
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Setup Objective 2: Mount cartridge in wand and adjust stylus overhang.
Objectives:
1. Counterweight mounting
2. Wand insertion/extraction procedure.
3. Vertical cartridge alignment tool.
4. Mount your “test” or “production” cartridge.
5. Adjust stylus overhang.
Counterweight mounting.
The counterweight is Delrin, cast with Bismuth alloy, and then milled into a cube. It is shipped with the
accessories to prevent damage during transport. Find the counterweight, the black counterweight rod,
and the two blue round knurled thumb nuts (5x20mm). Notice that the counterweight has semi-circular
voids on two sides, hosting the two thumb nuts. To get a feel for the fit and rotation, do a “dry-fit” of
the thumb nuts and the counterweight onto the counterweight rod. Position the counterweight and
thumb nuts, untightened, approximately in the middle of the counterweight rod.
Find the 5mm “L” wrench and insert it into the hex head end of the counterweight rod. Point the
opposite end of the counterweight rod at the “hole” end of the breech block and insert therein. Rotate
the wrench until you feel resistance to further rod insertion. Give it an additional eighth turn, and pull
the “L” wrench out of the counterweight rod.
To adjust the position of the counterweight loosen the blue thumb nut in the direction that the
counterweight should move, and then rotate the other blue thumb nut in the same direction, to again
snug up to the counterweight.
When setting stylus tracking force, pay close attention to the counterweight’s distance from the outer
gimbal. The wand and breech block must swing freely, not touching the outer gimbal. Binding could
occur if the counterweight is adjusted too close to the gimbals.
Wands: insertion/extraction procedure.
The lower mass “ladder” wand comes with the green vertical cartridge alignment tool pre-mounted.
The end of the wand that inserts into the breech block has a pair of sliding square grooves. These
grooves will fit snugly into the breech block’s square grooves.
9
You should insure that the volume level is are at zero prior to all wand insertions and extractions.
Wand Insertion: Wand top facing UP: with your left hand, grasp the wand by the thumb and forefingers
approximately in the middle where vertical grip grooves reside. With your right hand, firmly grip the
two smooth (non-rod) sides of the counterweight and hold the counterweight and breech box steady.
Now, with your left hand, begin sliding the wand onto the two grooves located at the front of the breech
block. Slow, steady sliding is recommended, no fast or irregular movements. Eventually the wand will
“bottom-out” onto the breech block when the six male gold connectors fully seat inside the six female
gold connectors located near the front/center of the breech block. Connections for the 4 signal wires
and two LED stylus spotlight wires are now complete.
WARNING: The bearings are stainless steel, the pivot points are 10.9 steel, but the inner gimbal is
Delrin. The bearings and pivots are rigid, but Delrin has some flexibility by nature. If pushed without
any constraining support it is possible to flex the Delrin enough so that a pair of bearing/pivots could
be pressured to unseat (as opposed to break). The method described here for wand insertion and
extraction works well,
and
MUST
be practiced without
any
exception
s
.
extraction works well,
and
MUST
be practiced without
any
exception
s
.
Vertical Tracking Force: For normal cartridges, now would be the time to utilize a vertical force gauge
and adjust the counterweight position to comply with the cartridge manufacturer’s stylus force
recommendations.
Vertical cartridge alignment tool.
The green vertical cartridge alignment tool comes pre-mounted on the lightweight ladder wand. It is the
last check that is made before shipment. Since the green vertical alignment tool can be pressed down
onto the platter surface manually by finger pressure, setting tracking force is not yet required
This tool insures that the stylus will be standing up perfectly straight when attached to the cartridge
mounting pad. Less than perfect vertical could be the result of either the front tower’s elevator or the
back tower’s elevator not being adjusted to exactly at the same vertical displacement from the tone
arm’s base plate surface
.
arm’s base plate surface
.
Press the blue LED button to send the lift/lower motor into cycling the wand down toward the platter.
Manually push the green cartridge alignment tool down onto the platter and observe whether any light
is present at the left or right bottom edge. If present, then adjust one of the tower elevators to
compensate. Read the next paragraph for wand extraction process, then remove the wand, dismount
the green cartridge alignment tool for placement back into the accessories box.
Wand Extraction: With your left hand, grasp the wand by the thumb and forefingers closer toward the
channel where a second set of vertical grip grooves are present. With your right hand, firmly grip the
two smooth (non-rod) sides of the counterweight and hold the counterweight and breech box steady.
Now, with your left hand, begin pushing against the Plexiglas channel, while sliding the wand straight
back and away from the breech block. Slow, steady sliding pressure is recommended, no fast or
irregular movements. Eventua
lly the wand will “free” itself from the breech block, with signal and LED
10
irregular movements. Eventua
lly the wand will “free” itself from the breech block, with signal and LED
connections being disengaged.
