Raleigh Audio RAKK dac Mark III Extreme Preamplifier User manual

RAKK dac
Ralei
g
h Audio
K&K Audio
RAKK dac
Mark III
Extreme
Preamplifier
Assembly Manual
Version 1.1 © 2010 – 2011 Raleigh Audio

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This completed Extreme Preamplifier has a silver face plate and knobs. A black faceplate and knobs is available.
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1

GeneralInformation
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The Extreme Preamplifier is a semi-custom kit, which means that several standard offerings are
combined to form the base, while the inputs and outputs are added as options to the base. You
can choose to have from one to six inputs, which may be a mix of balanced (XLR) and single-
ended (RCA) jacks. You can choose to have from one to three outputs, which may be a mix of
balanced (XLR) and single-ended (RCA) jacks.
While a mix of analog and digital inputs is possible, this makes the preamplifier into a different
product – the Extreme Hybrid, and thus is not covered in this manual.
This kit is relatively straightforward to build, but assumes some prior skill with a soldering iron
and some knowledge of electronic components and assembly.
Kit version
Use this manual with the Extreme Preamplifier Mark III
•Use the applicable on-line manuals for component sub-assemblies.
Required Tools and Supplies
150 to 250 Watt soldering gun
35 to 50 Watt soldering iron
Phillips (cross point) screwdriver
Volt-Ohm-Milliamp Meter
Potentiometer adjustment tool (supplied)
1/16” hex (Allen) wrench (supplied)
5/64” hex (Allen) wrench (supplied)
1.5mm. hex (Allen) wrench (supplied)
2.5mm. hex (Allen) wrench (supplied)
1/4”, 5/16”, 1/2”, 9/16” open-end wrenches
Diagonal cutting pliers
Long-nose pliers
Wire stripper
Solder
Use the soldering gun only to solder the heatsink pins.
Use the soldering iron for all other components.
Support
RAKK dac and its associated components are produced through the joint cooperation of K&K
Audio and Raleigh Audio. You may contact us with questions on constructing this kit by sending
an e-mail message to [email protected] or [email protected]
2

Warnings and Cautions
Warning — a high voltage power supply (200VDC) is required to make the kit operate properly.
These voltages can be lethal. If you are not familiar with safe techniques for completing the
installation of this kit with a high voltage power supply, then you should seek someone who is
qualified to help you construct this kit safely. If you wish to review safe practice, consult the
ARRL Handbook for Radio Amateurs (www.arrl.org or often at used book stores), which has a
section on high voltage safety. Although they are usually referring to 1000v+, the techniques are
still applicable. As the purchaser, you assume responsibility for safe assembly, testing, and
application of this kit.
Caution – Use only solder that is intended for electrical circuits. Do not use acid or corrosive
flux of any kind.
Caution – Any MOSFET is subject to damage by static electricity. Thus, the MOSFETs need
special care and handling especially when the relative humidity is low. Make sure to discharge
any static electrical charge from your body before handling a MOSFET. You can discharge your
body by touching a water faucet or grounded electrical appliance.
Soldering Notes
To a large extent, the success of your kit-building endeavor depends on your ability to solder
properly. Aside from experience, there are two pretty important factors in this success. The first
is the soldering equipment. I recommend using a temperature controlled soldering station,
although any good soldering iron of 40 watts or greater will do. There are many soldering
stations on the market; I have had good experience with the moderately priced Hakko Model
936. If you do have or purchase a soldering station, or even use your existing soldering iron, I
have found a chisel style tip of about 2mm-2.5mm width to be the most useful. You can use the
flat part for large solder joints and the corner for small solder joints. The second factor is the
selection of the solder you will use. The PC boards and most of the electrical components in the
kit are lead-free, as the movement in the EU has forced manufacturers to remove the lead (and
other dangerous heavy metals) from their products. Decent (notice, I didn’t write “good”) lead-
free solder exists, such as Cardas Tri-Eutectic, but it is not so easy to use unless you have some
soldering experience. Lead-free solder tends to melt in a sluggish way and the resulting solder
joints are not the customary shiny silver color, so it’s difficult to avoid “cold” solder joints
without experience. It’s up to you to decide what to use. Choose based on your experience. I
use Cardas Quad Eutectic and can recommend it without reservation; however other high quality
solders may work just as well. Take care in handling electronic solder as most of it still contains
a significant quantity of lead. Wash your hands thoroughly after construction sessions and keep
all kit materials well out of the reach of small children.
Even though there is a “component side” and solder side” to the board, your might find it more
convenient to solder the leaded components from the component side.
3

TableofContents
General Information ......................................................................................................................................................2
Table of Contents...........................................................................................................................................................4
Assembly Instructions ...................................................................................................................................................5
Pre-wire the PC boards and Power Transformer ...........................................................................................................6
Pre-wire the Active Output........................................................................................................................................6
Pre-wire the RAKK Input..........................................................................................................................................7
Pre-wire the Power Transformer................................................................................................................................8
Panel Preparation.........................................................................................................................................................10
Bottom Panel Preparation ........................................................................................................................................10
Back Panel Preparation............................................................................................................................................11
Side Panel Preparation.............................................................................................................................................12
Front Panel Preparation ...........................................................................................................................................12
Panel Assembly ...........................................................................................................................................................13
Bottom Panel Assembly ..........................................................................................................................................13
Back Panel Assembly ..............................................................................................................................................16
Front Panel Assembly..............................................................................................................................................22
Final Assembly and Wiring .........................................................................................................................................23
Wire the Bottom Panel to the Back Panel................................................................................................................23
Wire the Bottom Panel to the Front Panel ...............................................................................................................26
Assemble the Panels ................................................................................................................................................31
Final Adjustments........................................................................................................................................................37
Adjust the Constant Current Sources.......................................................................................................................37
Final Assembly............................................................................................................................................................38
Parts List......................................................................................................................................................................39
Circuit kits ...............................................................................................................................................................39
Extreme Kit Contents ..............................................................................................................................................39
Document version history............................................................................................................................................42
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4

AssemblyInstructions
Before you start, read through the instructions completely to the end.
Inventory the kit contents to become familiar with the parts and to make sure you have
everything.
The assembly sequence is as follows:
1. Assemble all of the printed circuit boards
2. Pre-wire the printed circuit boards
3. Pre-wire the power transformer
4. Install PC boards and the power transformer on the bottom panel
5. Assemble the components on the back panel
6. Assemble the components on the front panel
7. Assemble the panels
8. Wire everything together
There are two sizes of stranded wire provided with the kit, #22 and #20. The larger diameter #20
is used for power and high voltage. The smaller diameter #22 is used for signal and low voltage.
Where a wire is to be connected to a PC board, prepare the end by stripping ⅛” insulation and tin
the bare wire. For other connections, strip ¼” and tin the end. Where a twisted-pair is called for,
provide about four or five twists per inch. Twisting wires together will shrink their length
slightly so you need to take this into account. With a very few exceptions, which are explicit,
insert the wire into the pad from the bottom, or solder side, of the board. Wires should be
dressed neatly as close to the bottom of the enclosure as possible.
Assemble the Printed Circuit Boards
You will assemble three boards for this project: a RAKK Input board, an Analog Select switch
board and an Active Differential Output adapter. While assembly of all of the boards is straight-
forward, the Active Differential Output is the most complex. Therefore, I recommend that you
leave that kit until you have assembled all of the other boards. The instructions for the Analog
Select switch board are included in the Analog Input manual.
The assembly manuals for the boards include installation instructions that you will not use.
Rather than using those general instructions, you will follow the specific installation
instructions contained in this manual.
Referring to the applicable on-line manuals, assemble the boards now.
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5

PrewirethePCboardsandPowerTransformer
In the following steps, the wires should be inserted into the solder side of the board. “Preparing a
wire” means to strip ⅛” of insulation from both ends of the wire and tin the ends.
Because each wire has a “from” end and “to” end, and only one end is pre-wired, some pads are
not wired in this section. A signal line or a function will likely have the same name on the
“from” end as it does on the “to” end, therefore don’t just go by the name when you install the
wire. Rather, check that you are installing it on the proper board.
Basically there are two ways to make a twisted pair or a multi-wire cable. The quick and easy
way is to use an electric drill. So if you have a variable speed drill, all you have to do is to put
the wires together in the drill chuck and turn on the drill. It might take a little practice to get the
tension and speed right but once you get the knack, it is quick and easy to do. If you don’t have a
drill handy, the old-fashioned way of manually twisting the wires works fine. I have described
how I do it here. To make a multi-wire cable, first make a twisted pair and then wrap a third
wire around the twisted pair following the lay of one of the wires. Then stretch this new wire like
you did the others. Follow with a fourth and fifth wire as needed.
About 5% shrinkage occurs when making a twisted pair. So for example, if you wanted a 10”
long twisted pair, you would make it from two 10½” wires. It would be better to err a little on the
long side because you can always trim the length when you install the twisted pair.
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PrewiretheActiveOutput
Wire the Volume Control on the Active Output
1. Prepare a 6” #22 blue/black twisted pair.
•Connect the blue wire to the volume control “L+” pad.
•Connect the black wire to the volume control “L-” pad.
2. Prepare a 5” #22 orange/black twisted pair.
•Connect the orange wire to the volume control “R+” pad.
•Connect the black wire to the volume control “R-” pad.
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Wire the External Mute
6

3. Using a craft knife cut a gap in the trace that connects the two “external mute”
pads.
4. Prepare a 24” #22 black/black twisted pair.
•Connect the two wires to the two “external mute” pads.
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The “Input Select” pads are not used.
The “From RAKK dac” pads are not used.
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PrewiretheRAKKInput
The length of the wires between the Active Output and RAKK Input will vary depending on the
number of inputs on the RAKK Input board. The lengths here are the maximum expected and
may be too long for your unit. Trim them to the correct length when you attach the other ends.
Wire the Outputs on the RAKK Input board
5. Prepare a 17” #22 blue/black twisted pair.
•Connect the blue wire to the left “OUT +” pad.
•Connect the black wire to the left “OUT -” pad.
6. Prepare a 12” #22 orange/black twisted pair.
•Connect the orange wire to the right “OUT +” pad.
•Connect the black wire to the right “OUT -” pad.
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Wire the 12V on the RAKK Input board
7. Prepare a 13½” #20 yellow wire and connect it to the 12V pad.
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7

PrewirethePowerTransformer
For the following steps, refer to the LL1683 Data sheet.
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1. Wire the transformer for your Mains line voltage:
115VAC:
•Connect pin 2 to pin 12 with a #20 black wire.
•Connect pin 4 to pin 10 with a #20 black wire.
230VAC:
•Connect pin 4 to pin 12 with a #20 black wire.
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2. Fabricate a T-shaped AC power cable as follows:
•Cut a #20 black wire, 11 inches long. Do not strip the ends.
•Cut a #20 black wire, 19¾ inches long. Do not strip the ends.
•Cut a #20 white wire, 16¼” long. Do not strip the ends.
•Align the white wire with the longer black wire and twist them together for about 11”.
•Align the other black wire with the other end of the white wire and twist them together
for 3¾”.
•Go back to the first pair (that you twisted to 11”) and continue the twist until you get to
the junction of the second pair.
•Now twist the two black wires together until you get to the end. Don’t worry if the two
black wires are different length – you will trim them later.
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3. Wire the AC cable that you just fabricated:
•Trim the 3¾” black/white stub to be 3½” long.
•Separate the end of the stub for 2¼”.
•Trim 1¾” from the end of the black wire.
•Strip ¼” from the end of both wires and tin the ends.
•Connect the white wire to pin 10.
•Connect the black wire to pin 2.
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8

4. Wire the high voltage:
•Make a twisted-pair from two pieces of #20 red wire, one 9½” long and one 9¾” long.
Align the wires evenly at one end.
•Connect the longer wire at the uneven end to pin 17 on the power transformer.
•Connect the shorter wire to pin 15 on the power transformer.
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5. Connect the center tap in the following manner:
•Prepare a 12” piece of #20 black wire and strip 1” from one end. Connect the tip of this
end to pin 24 and then wrap the bare wire around pin 22. Solder both pins.
•Dress this wire towards pin 15 and wrap it around the red twisted pair following the lay
of the twist.
•Trim the black wire to be the same length as the two red wires.
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6. Wire the filament power
•Make a twisted-pair from two pieces of #20 grey wire, one 5” long and one 7¼” long.
Align the wires evenly at one end.
•Connect the longer wire at the uneven end to pin B1 on the power transformer.
•Connect the shorter wire to pin B6 on the power transformer.
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7. Wire the power indicator
•Cut the leads of the 22K (red, red, black, red, brown) resistor to be ½” long. Form a
loop, or hook, on each lead.
•Solder one end of the resistor to pin B2. Lay the resistor flat on the transformer
pointing towards the center of the transformer. You may choose to secure the resistor
with a drop of adhesive.
•Make a twisted-pair from two pieces of #22 black wire, one 10½” long and one 11½”
long. Align the wires evenly at one end.
•Connect the uneven end of this twisted-pair to the power
transformer: shorter wire to pin B5, and longer wire to the open end of the resistor.
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9

PanelPreparation
Cut one 10” x 2” piece of damping material into two pieces: 10” x 1”.
Cut another 10” x 2” piece of damping material into three pieces:
Two, 8” x 1” and one, 2” x 2”.
Cut the remaining 10” x 2” piece of damping material into four pieces:
Two, 4” x 1”, one, 8” x 1” and one, 2” x 2”.
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BottomPanelPreparation
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Note that the lip on the bottom panel points towards the inside.
1. Install the four feet in their holes close to the corners of the panel.
Use a 6-32 x ½” screw, flat washer and Kep nut on each foot.
Place the washer between the head of the screw and the rubber foot.
2. Install one piece of 8” x 1” damping material on the inside of the bottom panel, centered
between the vents and the lip.
3. Install one piece of 4” x 1” damping material on the inside of the bottom panel, next to and
centered on the left side of the vents.
4. Install one piece of 4” x 1” damping material on the inside of the bottom panel, about 1”
away from and centered on the right side of the vents.
Note that the bottom panel in the picture above has lines drawn to show where the transformer
and circuit board will be mounted.
10

TopPanelPreparation
1. Place the top panel such that the inside surface of the panel faces up and the edge with the lip
(front) is away from you.
2. Install one piece of 10” x 1” damping material on the inside of the top panel, centered
between the vents and the lip.
3. Install one piece of 10” x 1” damping material on the inside of the top panel, centered
between the back of the panel and the vents, but closer to the vents so as not to interfere with
attaching the back panel.
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BackPanelPreparation
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The back panel consists of two parts: an open frame that attaches to the other panels and a
customized insert that contains the jacks.
Place the insert inside the frame and secure them with ten 4-40 x ⅜” screws and ten Kep nuts.
Because two panels being clamped together inhibit vibration resonances, no damping treatment
is required for this panel.
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11

SidePanelPreparation
1. Install an 8” x 1” piece of damping material centered on the inside of the left panel.
2. Install an 8” x 1” piece of damping material centered on the inside of the right panel.
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FrontPanelPreparation
Install the two remaining 2” x 2” pieces of damping material on the inside of the front panel.
•Position them evenly and you may wish to cut one or both pieces to provide a more even
distribution.
•Make sure that there is at least ⅝” between the damping material and either the top edge
or bottom edge of the panel.
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12

PanelAssembly
BottomPanelAssembly
Steps preceded by a “note” (♪) deal with components which must be oriented properly.
TIP – To ease the alignment of the mounting holes with standoffs, slightly loosen the standoffs
from the board, install the screws through the bottom panel into the standoffs and then re-tighten
the standoffs.
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♪
Mount the power transformer
1. Mount the LL1683 transformer in its location using the four 4mm metric screws. Orient the
transformer such that the high-voltage (shorter) pins are towards the front of the panel. The
front of the panel has the lip.
•Dress the white/black twisted pair toward the edge of the panel. Then the white/black
twisted pair will go towards the rear of the panel and the black/black twisted pair will go
to the front of the panel.
•Dress the black twisted pair for the power indicator toward the front of the panel.
•Dress the grey twisted pair that will power the filaments toward the center of the panel.
•Dress the red/red/black twisted trio toward the center of the panel.
13

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14

♪
Mount the Active Output board
2. Mount the Active Output board in its location in the center of the chassis.
Orient the board such that the power input pads are closest to the power transformer.
Do not secure the board yet.
3. Locate the grey twisted pair that is connected to transformer pins B1 and B6. Connect this
twisted pair to the “6.3VAC” pads.
4. Locate the red twisted pair that is connected to transformer pins 15 and 17 and has a black
wire wrapped around it.
•These three wires will be connected to the “250V-0-250V” pads.
•Connect the two red wires to the outer pads.
•Connect the black wire to the center pad.
5. Secure the board with thirteen 6-32 x ¼” screws.
6. Dress the twisted pairs for the volume control towards the front of the panel.
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15

BackPanelAssembly
You may have as few as two pairs or as many as six pairs of input jacks. You may have as few as
one pair or as many as three pairs of output jacks. The jacks may be RCA jacks, XLR jacks or a
mix of the two. Here are some general guidelines for mounting the jacks:
•Mount the jacks from the inside of the panel.
•The XLR jacks are secured with two 4-40 x ⅜” screws and nuts.
•Orient XLR jacks such that the center pin is on the bottom.
•XLR inputs use female jacks (with a tab), XLR outputs use male jacks.
There is a switch associated with the output jacks that selects the proper grounding for the jacks.
If all of the output jacks are RCA, then the switch will be labeled “Ground/Lift.”
If there is a mix of RCA and XLR output jacks, then the switch will be labeled “XLR/RCA.”
If all of the output jacks are XLR, then the switch is not needed and will not be present.
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Mount the jacks and hardware:
1. Install the analog input jacks. For RCA jacks, position the red washer on the outside of the
right jack and the white washer on the outside of the left jack.
2. Install the analog output jacks. For RCA jacks, position the red washer on the outside of the
right jack and the white washer on the outside of the left jack.
3. If you have chosen to have unused input holes for future expansion, install filler plugs in
those locations.
4. Install the DPDT toggle switch in the “RCA/XLR” (“Gnd/Lift”) location.
Position the switch so the toggle alternates between the “RCA” and “XLR”.
5. Install the fuse in the power connector. Note that there is also a place for the spare fuse in the
fuse holder.
6. Install the power connector from the outside of the panel. Orient the connector such that the
fuse is on the bottom, and secure with two 4-40 x ⅜” screws and nuts.
7. Install the solder lug on the inside of the panel, in the hole adjacent to the power connector.
Secure with a 4mm screw and nut. Orient the solder tab away from the power connector and
form the solder tab at a 90-degree angle away from the panel.
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16

This example of a back panel has three pairs of RCA inputs and two pair of RCA outputs.
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Wire the Input Jacks to the RAKK Input board
Each input jack will be individually connected to the RAKK Input board so there is no common
input grounding on the panel. However, XLR jacks will have their shield (pin 1) connected to the
chassis at the connector.
Repeat each instruction for each jack. Use a #22 blue/black twisted pair for the left channel and a
#22 orange/black twisted pair for the right channel.
It takes a lot of heat to solder the shell of the Cardas RCA jacks – you may want to use a
soldering gun to solder the shell.
1. Notice that there is a metal tab adjacent to pin 1 on the XLR jacks. Connect a wire between
this tab and pin 1 on each jack.
2. Connect a 1¼” twisted pair to each XLR jack. Solder the blue (orange) wire to pin 2 and the
black wire to pin 3.
3. For each RCA jack, make a twisted pair from a 1¼” blue (orange) wire and a 1¾” black wire.
Solder the blue (orange) wire to the center post and the black wire to the shell of the jack.
4. Dress the left channel wires toward the top of the panel and the right channel wires towards
the bottom of the panel.
5. Install the 1” standoffs on the RAKK Input board on the same side of the boards as the
relays.
♪
6. Mount the RAKK Input board in its location on the back panel.
•Orient the board such that the input connector is closest to the center of the panel.
•Secure with four 6-32 x ¼” screws.
17

7. Now would be a good time to personalize the jumpers on the RAKK Input board if you
haven’t already done so. Refer to the instructions in the RAKK Input manual.
8. Connect the twisted pair from each input jack to the “IN” pads on the RAKK Input board.
Solder the blue (orange) wire to the “+” pad and the black wire to the “-” pad.
————————————————————————————
Wire the power connector:
1. Wire the safety ground:
This wire will be used a single-point chassis ground buss to which other wires are soldered.
•Strip the insulation from the 2” piece of #18 solid wire so that it is bare.
•Connect one end of this wire to the top (center from the outside) terminal on the power
connector.
•Dress the wire straight to the side and then down toward the solder lug. Connect the wire
to the tab on the solder lug.
•Solder both ends of the wire.
•Tin the wire by flowing solder over the whole length.
The “hot” and “neutral” pins will be wired later.
————————————————————————————
Wire the chassis ground connections:
The length of the first two of these wires will vary depending on your configuration of input and
output jacks.
1. Connect a 12” #20 green wire between the ground buss at the power connector and the
“chassis” pad on the RAKK Input board. Solder both ends and dress the wire along the top
edge of the panel.
2. Connect a 6” #20 green wire from both center pins on the “RCA/XLR” (Gnd/Lift) switch to
the ground buss. Solder both ends and dress the wire along the center of the panel.
3. Prepare an 11” #20 green wire. Connect it to the ground buss.
4. Prepare a 26” #20 green wire. Connect it to the ground buss.
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18

Wire the output jacks:
Even though you may have several pairs of output jacks of different types, they are electrically a
single pair of outputs. The multiple pairs of output jacks are wired in parallel. Use orange/black
for the right channel and blue/black for the left channel.
Observe the labeling on the RCA/XLR (Gnd/Lift) switch. The switch and the labeling may be
positioned in any orientation but will be wired in only one way – such that when the switch is in
the RCA (Gnd) position, the shells of the RCA jacks are grounded. The center two pins are
switched to either of the two outside pins. The switch is constructed so that the switch handle is
pointing in the direction of the two outside pins that are not connected to the center pins. For
example, if the switch is oriented vertically with RCA (Gnd) on the bottom, when the switch is
in the RCA (Gnd) position (down), then the center two pins are connected to the two pins that
are closest to the top of the panel. This orientation of the switch is assumed for these instructions
and your wiring should be adapted to match the orientation of your switch.
1. Notice that there is a metal tab adjacent to pin 1 on the XLR jacks. Connect a wire between
this tab and pin 1 on each jack.
2. Connect all of the positive pins together on the left channel jacks. The positive pin is pin 2 of
an XLR jack and the center pin of an RCA jack.
3. Connect all of the negative pins together on the left channel jacks. The negative pin is pin 3
of an XLR jack and the shell of an RCA jack.
4. Connect all of the positive pins together on the right channel jacks.
5. Connect all of the negative pins together on the right channel jacks.
6. Connect one of the two pins that is closest to the top of the panel on the RCA/XLR
(Gnd/Lift) switch to the shell of one of the left channel RCA jacks.
7. Connect the other of the two pins that is closest to the top of the panel on the RCA/XLR
(Gnd/Lift) switch to the shell of one of the right channel RCA jacks.
8. Prepare a 19” long #22 blue/black twisted pair. Attach this twisted pair to the left channel
output jack that is closest to the input jacks. Solder the blue wire to the positive pin (pin 2 of
an XLR or the center pin of an RCA) and the black wire to the negative pin (pin 3 of an XLR
or the shell of an RCA).
9. Prepare a 14” long #22 orange/black twisted pair. Attach this twisted pair to the right
channel output jack that is closest to the input jacks. Solder the orange wire to the positive
pin and the black wire to the negative pin.
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19