Rakk Dac Raleigh Audio Extreme Preamplifier Assembly Manual

Transcript

RAKK dac raleigh audio Extreme Preamplifier Assembly Manual Version 4.3 © 2010 – 2014 Raleigh Audio   This Extreme Preamplifier is available with either a black or silver faceplate 1 General Information     This manual provides instructions to build a state-of-the-art Extreme Preamplifier. The Extreme Preamplifier is a Line Stage providing four single-ended RCA inputs, two balanced XLR inputs, one single-ended RCA output and one balanced XLR output. Amplification and drive is provided by a fully balanced differential amplifier including extremely high-quality input transformers and output transformers. Two versions of the Extreme Preamplifier are possible: the “Premium” version, over the top using the highest quality components throughout and the “Standard” version, more modest version providing cost savings by using excellent, but not the best, components throughout. Both versions are presented in this manual. The wiring and assembly is the same for both versions, so in most cases pictures of only the Premium version are shown. 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. • 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 You may contact us with questions on constructing this kit by sending an e-mail message to [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”) leadfree 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 12V Relay power supply ....................................................................................................................... 7  Pre-wire the Analog Input ......................................................................................................................................... 7  Pre-wire the Differential Amplifier ........................................................................................................................... 8  Pre-wire the Power Transformer.............................................................................................................................. 10  Panel Preparation ......................................................................................................................................................... 13  Bottom Panel Preparation ........................................................................................................................................ 13  Back Panel Preparation ............................................................................................................................................ 14  Side Panel Preparation ............................................................................................................................................. 15  Front Panel Preparation ........................................................................................................................................... 15  Panel Assembly ........................................................................................................................................................... 16  Bottom Panel Assembly .......................................................................................................................................... 16  Back Panel Assembly .............................................................................................................................................. 21  Front Panel Assembly .............................................................................................................................................. 28  Final Assembly and Wiring ......................................................................................................................................... 30  Wire the Bottom Panel to the Front Panel ............................................................................................................... 30  Wire the Bottom Panel to the Back Panel................................................................................................................ 35  Assemble the Panels ................................................................................................................................................ 39  Final Adjustments ........................................................................................................................................................ 45  Adjust the Constant Current Sources ........................................................................................................................... 45  Final Assembly ............................................................................................................................................................ 46  Parts List ...................................................................................................................................................................... 47  Circuit kits ............................................................................................................................................................... 47  Extreme Kit Contents .............................................................................................................................................. 47  Document version history ............................................................................................................................................ 50    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. 2. 3. 4. 5. 6. 7. 8. Assemble all of the printed circuit boards Pre-wire the printed circuit boards Pre-wire the power transformer Install PC boards and the power transformer on the bottom panel Assemble the components on the back panel Assemble the components on the front panel Assemble the panels 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 sub-kits for this project: an Analog Input kit, a 12V Relay power kit, and a Differential Amplifier kit. While assembly of all of the boards is straight-forward, the Differential Amplifier 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. Several of the individual kits have a small amount of wire included with them. Use that wire for the kit it came with rather than using the bulk amount that is provided with the Extreme kit. Otherwise you will end up short of wire. Referring to the applicable on-line manuals, assemble the boards now.   5 Pre­wire 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. ————————————————————————————   6 Pre­wire the 12V Relay power supply     1. Prepare a 14” #22 red/black twisted pair. • • Connect the red wire to the DC Output “+” pad. Connect the black wire to the DC Output “-” pad. ———————————————————————————— 2. Connect a single 17” #22 black wire to the DC Output “-” pad. Wrap this around the red/black twisted pair for about 10”. ———————————————————————————— 3. Connect a single 9” #20 green wire to the DC Output “-” pad. ———————————————————————————— 4. Connect a single 10” #22 red wire to the DC Output “+” pad.   ———————————————————————————— Pre­wire the Analog Input    1. The Analog Input board will be pre-wired when it is mounted on the back panel. ————————————————————————————   7 Pre­wire the Differential Amplifier  Wire the Volume Control on the Differential Amplifier 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 6” #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. ———————————————————————————— Wire the Line Inputs on the Differential Amplifier 3. Prepare a 2½” #22 blue/black twisted pair. • • Connect the blue wire to the Left Line Input “L+” pad. Connect the black wire to the Left Line Input “L-” pad. 4. Prepare a 5½” #22 orange/black twisted pair. • • Connect the orange wire to the Right Line Input “R+” pad. Connect the black wire to the Right Line Input “R-” pad. 5. Connect a 3½” #22 black wire to the “From RAKK dac REF” pad. ———————————————————————————— Wire the External Mute 6. Using a craft knife, cut a gap in the trace that connects the two “external mute” pads. 7. Prepare a 23” #22 black/black twisted pair. • Connect the two wires to the two “external mute” pads. ———————————————————————————— 8 Wire the Ground on the Differential Amplifier 8. Connect a 13½” #20 green wire to the “chassis” pad. ———————————————————————————— The “From RAKK dac” pads are not used. ————————————————————————————   9 Pre­wire the Power Transformer  For the following steps, refer to the LL1683 Data sheet. ———————————————————————————— 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. ———————————————————————————— 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. ———————————————————————————— 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. ———————————————————————————— 10 4. Wire the high voltage: • • • Make a twisted-pair from two pieces of #20 red wire, one 7½” long and one 7¾” 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. ———————————————————————————— 5. Connect the center tap in the following manner: • • • Prepare a 10” 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. ———————————————————————————— 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. ———————————————————————————— 7. Wire the AC power for the 12V regulator • • • Make a twisted-pair from two pieces of #20 grey wire, one 4¼” long and one 6½” long. Align the wires evenly at one end. Connect the longer wire at the uneven end to pin B7 on the power transformer. Connect the shorter wire to pin B4 on the power transformer. ———————————————————————————— 11 8. Wire the power indicator • • • • Cut the leads of the 6.8K (blue, violet, red,) 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 9½” 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. ————————————————————————————   12 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 nine pieces: One (2” x 1”), four (6” x ½”) and four (3” x ½”). ———————————————————————————— Bottom Panel Preparation    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 the piece of 2” x 1” damping material on the inside of the bottom panel, centered where the power transformer will be mounted. 3. Install the four pieces of 3” x ½” and the four pieces of 6” x ½” damping material on the inside of the bottom panel, distributed as shown in the photo below. Be careful to allow at least ¼” clearance around each of the mounting holes. Note that the bottom panel in the picture above has lines drawn to show where the transformer and circuit boards will be mounted. 13 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. ———————————————————————————— Back Panel Preparation     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. ————————————————————————————   14 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. ———————————————————————————— Front Panel Preparation  1. 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. 2. Install an 8-32 x ½” setscrew in each of the five holes. The screw should be snug but do not over-tighten. ————————————————————————————   15 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. ———————————————————————————— ♪ 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 grey twisted pair that will power the -12V toward the right side of the panel. Dress the red/red/black twisted trio toward the center of the panel. 16 ———————————————————————————— 17 ♪ Mount the 12V Regulator module. 2. Place the 12V Regulator module in its location next to the power transformer. Orient the board such that the AC Input is closest to the edge of the panel. Do not secure the board yet. 3. Dress the grey twisted pair that is connected to transformer pins B4 and B7 along the edge of the panel to the Regulator module. Connect that grey twisted pair to the AC Input pads. 4. Dress the red/black twisted pair towards the center of the panel. This twisted pair has the single black wire wrapped around it. 5. Dress the single red wire towards the back of the panel. 6. Dress the single green wire towards the back of the panel. 7. Secure the board with four 6-32 x ¼” screws. ———————————————————————————— 18 ♪ Mount the Differential Amplifier board 8. Mount the Differential Amplifier 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. 9. Locate the grey twisted pair that is connected to transformer pins B1 and B6. Connect this twisted pair to the “6.3VAC” pads. 10. 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. 11. Locate the red/black twisted pair that is connected to the 12V power supply and has a black wire wrapped around it. • • • Connect the red wire of the twisted pair to the “12V+”pad on the output board. Connect the black wire of the twisted pair to the “12V-”pad on the output board. Dress the extra black wire towards the front of the panel. 12. Secure the board with thirteen 6-32 x ¼” screws. 13. Dress the Line Level Input wires towards the end of the panel. 14. Dress the twisted pairs for the volume control towards the front of the panel. 15. Dress the black twisted pair from the “external mute” pads towards the front of the panel. ———————————————————————————— 19 ———————————————————————————— ♪ Mount the Line Stage Input board 16. Mount the Line Stage Input board in its location near the end of the chassis. Orient the board such that the output pads are closest to the Differential Amplifier. Do not secure the board yet. 17. Locate the blue/black twisted pair from the Left Line Input on the Differential Amplifier. • • Connect the blue wire to the “Left Output +” pad. Connect the black wire to the “Left Output -” pad. 18. Locate the orange/black twisted pair from the Right Line Input on the Differential Amplifier. • • Connect the orange wire to the “Right Output +” pad. Connect the black wire to the “Right Output -” pad. 19. Connect the black wire from the “From RAKK dac REF” pad to the “REF” pad. You will secure the board later. ———————————————————————————— 20   ———————————————————————————— Back Panel Assembly  You have six pairs of input jacks: four pair of RCA and two pair of XLR. You have two pairs of output jacks; one RCA pair and one XLR pair. 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, labeled “XLR/RCA,” associated with the output jacks, that selects the proper grounding for the jacks. ———————————————————————————— 21 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. Note that here we are using the convention that the left channel is on the top of the panel when mounted on the chassis and the right channel is on the bottom of the panel. 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. Install the DPDT toggle switch in the “RCA/XLR” location. Position the switch so the toggle alternates between the “RCA” and “XLR”. 4. Install the fuse in the power connector. Note that there is also a place for the spare fuse in the fuse holder. 5. Install the power connector from the inside 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. 6. 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. 22 Wire the Safety Ground on the Power Connector: This wire will be used a single-point chassis ground buss to which other wires are soldered. • • • • • Strip the insulation from the 2½” 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 Chassis Ground to the Output Jacks Connect a 6½” #20 green wire from both center pins on the “RCA/XLR” switch to the ground buss. Solder both ends and dress the wire along the bottom of the panel. ———————————————————————————— Wire the Output Jacks: Even though you have two pairs of output jacks of different types, they are electrically a single pair of outputs. The two 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 switch. The switch is wired such that when the switch is in the RCA 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 such that the switch handle is pointing in the opposite direction of the two outside pins that are connected to the center pins. For example, with the switch oriented horizontally, when the switch is in the RCA position, then the center two pins are connected to the two pins that are closest to the power connector. The pins on the XLR jacks are numbered on the outside of the jack. Note that the pins on the female jacks (inputs) are a mirror image of the pins on the male jacks (outputs.) 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. 23 1. Notice that there is a metal tab adjacent to pin 3 on the XLR output jacks. On each jack, connect a #22 black wire between this tab and pin 1. 2. Connect a #22 blue wire between the center pin of the left (top) RCA jack and pin 2 of the left (top) XLR jack. 3. Connect a #22 orange wire between the center pin of the right (bottom) RCA jack and pin 2 of the right (bottom) XLR jack. 4. Connect a #22 black wire between the shell of the left (top) RCA jack and pin 3 of the left (top) XLR jack. 5. Connect a #22 black wire between the shell of the right (bottom) RCA jack and pin 3 of the right (bottom) XLR jack. 6. Looking at the back of the RCA/XLR switch, locate the pin which is closest to the XLR jacks and closest to the top of the panel. Connect a #22 black wire between this pin and the shell of the left (top) RCA jack. 7. Looking at the back of the RCA/XLR switch, locate the pin which is closest to the XLR jacks and closest to the bottom of the panel. Connect a #22 black wire between this pin and the shell of the right (bottom) RCA jack. 8. Prepare a 19” long #22 blue/black twisted pair. Attach this twisted pair to the left channel XLR jack. Solder the blue wire to the positive pin (pin 2 of an XLR) and the black wire to the negative pin (pin 3 of an XLR.) 9. Prepare a 14” long #22 orange/black twisted pair. Attach this twisted pair to the right channel XLR jack. Solder the orange wire to the positive pin (pin 2 of an XLR) and the black wire to the negative pin (pin 3 of an XLR.) ———————————————————————————— 24 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 have their shield (pin 1) connected to the chassis at the connector. Use a blue/black wires for the left channel and orange/black wires 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. The pins on the XLR jacks are too long and will interfere with mounting the Analog Input board. Each pin has a main shaft and a tip. For each pin on all of the XLR jacks, bend the tip, where it meets the shaft, horizontal to the panel. Don’t worry if a tip breaks off – you will solder the wires to the shaft. 2. For each XLR jack, solder 1¼” blue (orange) wire to pin 2 and the 1½” black wire to pin 3. Strip ⅛” from the other end of each wire. 3. For each left RCA jack, solder a 1” blue wire to the center post. Strip ⅛” from the other end. 4. For each left RCA jack, solder a 1½” black wire to the shell of the jack. Strip ⅛” from the other end. 5. For each right RCA jack, solder a 1½” orange wire to the center post. Strip ⅛” from the other end. 6. For each right RCA jack, solder a 2” black wire to the shell of the jack. Strip ⅛” from the other end. 7. Dress the left channel wires toward the top of the panel and the right channel wires towards the bottom of the panel. 8. Install the 1” standoffs on the RAKK Input board on the same side of the boards as the relays. Secure the standoffs with 6-32 x ¼” screws. ♪ 9. 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. 10. 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. ———————————————————————————— 25 Wire Chassis Ground to the Analog Input board: Connect a 7½” #20 green wire from the “chassis” pad on the Analog Input board to the ground buss. Solder both ends and dress the wire along the top of the panel. ———————————————————————————— Pre-Wire the Outputs from the Analog Input board: There are two sets of output pads on the board – one set on each end of the board. You will use the set closest to the end of the back panel. 1. Connect a 4” #22 orange/black twisted pair to the bottom (right) pair of “OUT” pads from the back side of the board. Connect the orange wire to the “+” pad and the black wire to the “-” pad. 2. Connect a 6½” #22 blue/black twisted pair to the top (left) pair of “OUT” pads from the back side of the board. Connect the blue wire to the “+” pad and the black wire to the “-” pad. ———————————————————————————— 26 27 Front Panel Assembly  Suggestion: You may want to place a towel on your work surface to ensure that you don’t scratch the panel. ———————————————————————————— 1. Notice that the Power-On LED has one lead that is longer than the other. This identifies the functions of the leads – the longer lead is the anode and the shorter lead is the cathode. You will now shorten both leads while keeping the length distinction. • • Cut the shorter lead on each LED to be ¼” long Cut the longer lead on each LED to be ⅜” long 2. Mount the Power-On LED in its hole and secure it in place with a drop of adhesive. 3. Install the Power on/off switch in its location on the right end (from the front) of the panel using the supplied nut. Tighten the nut snug but be careful to not over-tighten the nut because the thread is plastic and it may strip. 4. Install the ribbon cable in the connector on the Analog Select board. Orient the cable so that it goes away from the switch. 5. Install the input select switch and PC board in its location on the left end (from the front) of the panel. Install the lock-washer on the switch between the switch and the panel. Orient the PC board such that the cable is on the bottom. Tighten the nut snug but be careful to not over-tighten the nut because the thread is plastic and it may strip. 6. Pre-wire the Standard volume control Skip this step if you are building the Premium version of the preamplifier • Position the volume control such that the pins are facing up and the shaft is pointing towards you. • Notice that there are two rows of three pins each. Solder a jumper wire between the left-most pin and the center pin on each row. 28 7. Install the volume control in the remaining hole. 8. Install the five 8-32 x ½” setscrews. ————————————————————————————   29 Final Assembly and Wiring  ———————————————————————————— Wire the Bottom Panel to the Front Panel    Lay the front panel down adjacent to the bottom panel where it will be installed. ———————————————————————————— Trim the lengths of the wires as needed in the following steps. ———————————————————————————— 30 Wire the Premium Volume Control Skip this section if you are building the Standard version of the preamplifier. 1. Connect the twisted pairs from the “volume control” pads on the Differential Amplifier board to the volume control as follows: • • • • Connect the blue wire to the tab extending from the switch wafer closest to the front panel. Connect the associated black wire to the “com” pad on the board closest to the front panel. Connect the orange wire to the tab extending from the switch wafer closest to the back of the switch. Connect the associated black wire to the “com” pad on the board closest to the back of the switch. ———————————————————————————— 31 Wire the Standard Volume Control Skip this section if you are building the Premium version of the preamplifier 1. Connect the twisted pairs from the “volume control” pads on the Active Output board to the volume control as follows: Connect the orange/black pair to the set of pins closest to the front panel. • Connect the orange wire to the pair of pins that are connected together. • Connect the associated black wire to single pin in that set. Connect the blue/black pair to the set of pins furthest from the front panel. • Connect the blue wire to the pair of pins that are connected together. • Connect the associated black wire to single pin in that set. 32 Wire the Power Switch The power switch has four terminals. Two of the terminals will be used to switch the mains power and the other two terminals are used for the external mute. 2. Locate the #20 black twisted pair that is an extension from the white/black power cable. Connect it to the two terminals closest to the bottom panel. It does not matter which wire goes to which terminal. 3. Locate the #22 black twisted pair from the “external mute” pads on the Differential Amplifier. Connect it to the other two terminals on the power switch. It does not matter which wire goes to which terminal. Wire the Power-on LED 4. Locate the #22 black twisted pair from the pins B5 and B2 on the power transformer. 5. Solder the wires to the LED leads about ⅛” from the body of the LED. It does not matter which wire goes to which lead. ———————————————————————————— Wire the Select Switch 6. Connect the black wire from the 12V regulator to the “com” pad on the Analog Select board. ———————————————————————————— 33 Mount the Front Panel 7. Mount the front panel onto the bottom panel. • The stud in the center bottom of the front panel fits into the hole in the lip of the bottom panel. • Secure the panel with an 8-32 KEP nut on the center stud only finger-tight. 8. Neatly dress the wires along the bottom panel close to the front panel. Dress the ribbon cable directly back towards the rear of the panel. Place this cable under all of the other wires. 34 Wire the Bottom Panel to the Back Panel  Trim the length of these wires as needed. ———————————————————————————— • Lay the back panel down adjacent to the bottom panel where it will be installed. • Dress the wires along the bottom edge of the panel towards the opposite end from the power connector. • Fold the ribbon cable at a right angle and dress it towards the power connector. • Dress the ground wires towards the ground buss. • Dress the red wire from the 12V power supply towards the Analog Input board. ———————————————————————————— Wire 12V Power • • • • Dress the red wire from the 12V regulator close to the chassis Route it to the “12V” pad on the RAKK Input board Trim it to length Connect it to the “12V” pad ———————————————————————————— Connect the Ribbon Cable • • Dress the ribbon cable along the chassis, and then back to the connector on the RAKK Input board. Plug the ribbon cable into the connector on the RAKK Input board. ———————————————————————————— 35 Wire the AC Power and Ground Position the back panel on the back of the bottom panel and secure it with three 6-32 screws. 1. Dress the green wire from the Differential Amplifier “chassis” pad close to the chassis and connect it to the ground buss on the back panel. 2. Dress the green wire from the 12V regulator close to the chassis and connect it to the ground buss on the back panel. 3. Dress the power cable that is connected to transformer pins 2 and 10 as follows: • Dress the cable to the edge of the panel. • Dress the white/black twisted pair along the edge of the bottom panel toward the back of the panel. • The black twisted pair was previously connected to the power switch. 4. Connect the white/black cable to the power connector as follows: • Trim ½” from the end of the black wire. • Strip ¼” from the end of both wires and tin the ends. • Connect and solder the white wire to the center pin. • Connect and solder the black wire to the bottom pin. ———————————————————————————— 36 ———————————————————————————— Wire the Line Inputs 5. Connect the blue/black twisted pair from the left “OUT” pads on the RAKK Input board to the left “Line Input” pads on the Differential Amplifier. Connect the blue wire to the “+” pad and the black wire to the “-” pad. 6. Connect the orange/black twisted pair from the right “OUT” pads on the RAKK Input board to the right “Line Input” pads on the Differential Amplifier. Connect the orange wire to the “+” pad and the black wire to the “-” pad. 7. Secure the Line Stage Input board with four 6-32 x ¼” screws. ———————————————————————————— Wire the Outputs 8. Connect the orange/black twisted pair from the right output jack to the “Right Output” pads on the Differential Amplifier. Connect the orange wire to the “+” pad and the black wire to the “-” pad. 9. Connect the blue/black twisted pair from the left output jack to the “Left Output” pads on the Differential Amplifier. Connect the blue wire to the “+” pad and the black wire to the “-” pad. ———————————————————————————— 37 ————————————————————————————      38 Assemble the Panels    The back panel has been temporarily mounted on the bottom panel so that the two panels could be wired together. Likewise, the front panel has been temporarily mounted on the bottom panel. You will now permanently mount and adjust all of the panels so that they fit together nicely. You will tighten the screws in a specific order. As you do, ensure that the side panels and back panel stay in alignment with the edges of the bottom panel. This is a two-step process with the screws first being slightly tightened to the extent that the side panels can be moved sideways with some force, but won’t return on their own to their previous position. I will use the term “snug up” for this first step. Then, when everything is snug and in alignment, the screws will be tightened firmly. Use 6-32 x ¼” button head screws for assembling the bottom, sides and back panels. Use 6-32 x ¼” Phillips head screws for securing the top panel. Position the back panel 1. Slightly loosen and then snug up the three screws securing the back panel to the bottom panel. 2. Align the surface of the back panel with the edge of the bottom panel. 3. Make sure that the left and right edges of the back panel align with the left and right edges of the bottom panel. 4. Firmly tighten the three screws securing the back panel to the bottom panel. ♪ Position the two side panels on the ends of the bottom panel 1. Orient the side panels such that the ends of the side panels with the open holes are at the front and the ends of the panels with the insert nuts are at the back. 2. The studs on each end of the front panel fit into the holes on the ends of the side panels. 3. Install two screws through the back panel into each side panel. Leave these four screws slightly loose. 4. Install three screws through the bottom panel into each side panel. Leave these six screws slightly loose. 5. For each side panel, align the back edge of the side panel with the outside edge of the back panel and snug up the screws that secure the back panel to the side panel. 6. For each side panel, align the surface of the side panel with the edge of the bottom panel and snug up the screws that secure the side panels to the bottom panel. 39 Position the Front panel 1. Tighten the KEP nut in the middle of front panel while lifting the front panel so it contacts the tops of the mounting holes. This ensures that it's straight with respect to the shelf it will be sitting on. 2. Secure the front panel to the side panels with four 8 x 32 KEP nuts. Snug up these four nuts. Now with all of the screws and nuts snug, a side panel can be moved with some force, if need be. Position the top panel 1. Place the top panel on the top of the unit and check that the holes in the top panel are centered over the screw holes in the side panels and back panel. 2. Adjust the side panel alignment at the front by moving the top of the side panel left or right as is necessary to make the holes in the top panel align properly with the holes in the side panels. Secure the back, side and bottom panels 1. 2. 3. 4. Install nine screws in the top panel. Firmly tighten these screws. Firmly tighten the four screws securing the back panel to the side panels. Firmly tighten the three screws securing each side panel to the bottom panel. All screws should now be firmly tightened. Secure the front panel 1. Remove the top panel. 2. Firmly tighten the four KEP nuts that are securing the front panel to the side panels. 3. Place the top panel on the top of the unit and check that the holes in the top panel are still centered over the screw holes in the side panels and back panel. Set the top panel aside for now. You will install it after the final electrical adjustments are made. ————————————————————————————   40 41 42 43         44 Final Adjustments    Adjust the Constant Current Sources  1. Install a tube in locations V1 and V2. - 6H30P tube if Premium Line Stage - 6N6P tube if Standard Line Stage ———————————————————————————— 2. Power on the preamplifier and allow it to warm up for about one minute. ———————————————————————————— The adjustments that you are about to make interact. Therefore, the first time you may have to alternate adjustments to get them in range. ———————————————————————————— 3. Adjust the Left B+ to be 200V. Measure the voltage from the “Left B+” pad on the power board to the ground buss. Adjust R34. ———————————————————————————— 4. Adjust the Right B+ to be 200V. Measure the voltage from the “Right B+” pad on the power board to the ground buss. Adjust R30. ———————————————————————————— 5. Measure the voltage across each of the four CCS current sense resistors and adjust the associated potentiometers for 210mV across its resistor. Measure R39 R44 R49 R54 Adjust R38 R43 R48 R53 Voltage 0.210V 0.210V 0.210V 0.210V ———————————————————————————— 45 6. Allow the unit to warm up for about 15 minutes and then check and re-adjust the above six adjustments. ———————————————————————————— Final Assembly  1. Position the top panel on the top of the unit and secure with nine 6-32 x ¼” Phillips head screws. Tighten these screws. ———————————————————————————— 2. Install the knobs. Align the knobs and tighten the setscrews using a 1.5mm. hex wrench. The larger knob is for the volume control. ———————————————————————————— Congratulations! You have finished the assembly and installation. Enjoy the music and be aware that the character and quality of the sound will improve with time. The first 100 hours are most noticeable so hold off making evaluations until after that. 46 Parts List   Circuit kits  Refer to the parts list for each of these kits. The following kits are provided. • • • Analog Input Differential Amplifier for Line Stage 12V Relay power supply Extreme Kit Contents  In addition to the parts in the circuit kits and options listed above, these parts are provided: Chassis and Front Panel Parts Part Description Qty Chassis set Top, bottom, front, back frame, two sides 1 Foot Damping, black 4 Damping material 2” by 10” with adhesive backing 3 Power transformer LL1683 1 Volume control 1 Knob for volume control 1 Power switch Rotary, 1 Knob For power switch 1 Knob For select switch 1 LED blue 1 Resistor, 6.8K (blue, violet, red,) bands 1 47 Back panel Parts In addition to the parts received with the Analog Input kit, these parts are provided Part Description Qty Back Panel 1 AC inlet module Black with three prongs 1 Fuse 0.5A, 250V 5 x 20mm for 115VAC or 0.315A, 250V 5 x 20mm for 230VAC 2 RCA jack Output jacks 2 XLR jack Output jacks 2 Switch, toggle For RCA/XLR or Ground lift 1 standoffs 1” female/female 4 screws 6-32 x ¼” 8 Wire List From this, twisted pairs and individual pieces are called out in the individual assembly steps. Twisted wires are best made using a small electrical drill to do the twisting. Between 4 and 5 twists per inch is good. Be sure not to twist all the wire of a given color as some individual pieces are needed as well as twisted ones. Remember the twisting will slightly shrink the length so take this into account. Part Wire, 20 gauge Wire, 22 gauge Wire, 18 gauge Description Qty white 20” black 100” red 23” green 60” grey 15” yellow 15” black 140” blue 60” orange 50” solid 2” 48 Hardware List Part Description Qty Screw 4-4 x 0.375” button head 16 Screw 6-32 x 0.25” button head 21 Screw 6-32 x 0.5” button head 4 Screw 6-32 x 0.25” Phillips head 9 Screw 4mm x 8mm button head 5 Screw 8-32 x 0.5” setscrew 5 Nut 4-40 Kep nut (with star washer) 16 Nut 6-32 Kep nut (with star washer) 4 Nut 8-32 Kep nut (with star washer) 5 Nut 4mm machine nut 1 Washer 6-32 flat washer 4 Ground lug 4mm 1 standoff 6-32 x ⅜” female-female 4 Wrench Hex, 5/64” for 6-32 button head screws and 8-32 setscrews note 1 Wrench Hex, 1/16” for 4-40 screws note 1 Wrench Hex, 1.5mm, for knobs 1 Wrench Hex, 2.5mm for 4mm screws 1 Notes: 1. 2. 1/16” and 5/64” wrenches are included with the Differential Amplifier parts. The 1/16” wrench is almost the same size as the 1.5mm wrench, however even the small difference is important for properly fitting the screws. 49 Document version history  Version 4.0 4.1 4.2 4.3 Description Original clarify instructions clarify instructions (This document) clarify instructions 50