ANK L4 Construction Manual

Headphone amplifier c-core

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L4 Headphone Amplifier C-Core

Construction Manual

Version 1.06, June 2019

audionotekits@rogers.com

1-613-822-7188

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Page 1 L4 Headphone Amplifier C-Core Construction Manual Version 1.06, June 2019 audionotekits@rogers.com 1-613-822-7188...
Page 2: Table Of Contents
Table of Contents Section 1 — Introduction ……………………………………………..………………………….…………………… About ANKits …………………………………………………………..………………………….…………………… Evolution of the L4 Headphone Amplifier C-Core ……………………………………………………… Basic Operation of the Amplifier ……………………………………………………..…………… 1.3.1 Power Supply ..…………………………………………….……………………………………………… 1.3.2 The ECF80/EL84 Line and Output Amplification Stages …………………………… 1.3.3 Output Transformers ……………………………………………………….……………..…………...
Page 3 Section 4 — Choke installation ….…….…………………………….…………………………….…..….. Choke Installation ….…….………………………………………….…………………………….…...…... Section 5 —Power Supply PCB Installation ….…….…………………………………..….. Overview …………………………………………………………………………..………..….……………..… Parts List …………………………………………………………………………..………..….……………..… Building the Power Supply PCB ….…….………………………………….………….………………….….. 5.3.1 Mounting the Power Supply PCB …….…..…………..……………..…..... Power Supply PCB Interwiring ……………....……………….…………..…..………….... Section 6 — ECF80/EL84 PCB Installation ….…….……………………..………….…...…..
Page 4 Section 11 — Interwiring …..……………………………………..…....…........11.1 ECF80/EL84 PCB Interwiring …..………………………………………….…….……………...……... 11.1.1 Mounting the ECF80/EL84 PCB ………………………………………………….…..…… 11.1.2 Left/Right Channel Orientation …..………....………………......11.1.3 Power Supply PCB and Mains to ECF80/EL84 PCB Interwiring ……..…… 11.1.4 Output Transformers to ECF80/EL84 PCB Interwiring …......… 11.1.5 Attenuator Interwiring ……..................….
Page 5: Section 1 - Introduction
Section 1 Introduction Congratulations on your purchase of the DIY version of the ANKits L4 Headphone Amplifier C- Core. This is very high end and sophisticated piece of audio equipment that will surely become the showpiece of your sound system! We are excited that you have chosen to join us on the path of audio superiority, and thus, we have created this manual to help guide you through each step of the assembly process with as much detail and clarity as possible.
Page 6: About Ankits
Level 4 and 5 products so that a significant investment in a kit could be turned into a work of art! Since ANK Audio Kits was born in 2004, over 2,500 kits have been shipped to customers worldwide. Clearly, there is a real demand for high end audio kits and ANK Audio Kits has been delivering the goods now for 15 years.
Page 7: Evolution Of The L4 Headphone Amplifier C-Core
Khozmo step attenuators, and the front panel controls — and then we'll test everything. One of the key aspects of ANK Audio Kits success is our terrific support. We're always here to help you. So, rest assured, we'll make sure you succeed! Copyright ©...
Page 8: Basic Operation Of The Amplifier
Output Transformers (OTP-A and OTP-B) Primary — the Secondary or “output” of the Output Transformer connects to the headphone jacks. That is the complete audio path of the L4 Headphone Amplifier C-Core. Copyright © 2019 AudioNote Kits www.AudioNoteKits.com...
Page 9: Power Supply
1.3.1 Power Supply The goal was to design a power supply that will provide superior dynamics, detail and a Black background. It consists of the Mains transformer and Choke, IEC and rocker switch — the AC 120V (North America) enters the amplifier through the IEC and is sent to the Primary of the Mains transformer where it is converted to various AC voltages that are required by the amplifier.
Page 10: Equipment
Equipment Here is the list of equipment that will be required:  Philips screwdriver  A pair of quality wire strippers  A large, organized work area  Soldering iron station with wet sponge  Lead-based solder (4% Silver is recommended) 1.3.1 Overview of the Kit In your kit you will find a series of kit bags containing all the hardware, wire, and parts for the...
Page 11: Components
That way of looking at things sometimes now no longer applies. Please be assured that all resistors supplied with ANK Audio Kits are rated at least per the specified wattage: in some cases, a higher than specified wattage may be supplied.
Page 12: Diodes
1.4.6 Diodes match the stripe on the diode When installing diodes note that they are oriented with a stripe — with the banding (||) stencil on the board. 1.4.7 Hardware/Mechanical Not all of us are mechanically oriented. So, the kit is well laid out such that all the hardware is provided and bagged in individual sections, so things should make sense.
Page 13: Wire Color
1.4.10 Optional Finishing Touches From time to time we get asked about some of the build details of the ANK Finished Products that you can see in the pictures in the "Assembled Kits Gallery!" (https://ankits.smugmug.com/) on our website.
Page 14: Build Process
Build Process 1.6.1 Some Good Rules of Thumb for Building Your Headphone Amplifier  Take your time, prepare, and try and work on a small task each time you start to build the kit.  Instead of rushing through a second section — use the end of the session time to check your work.
Page 15 Here's another way of looking at how the manual is organized and how the sections fit into the 'big picture': the main sections are mapped so that they mirror how the components will be positioned in the amplifier chassis: Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 15...
Page 16: Electrical Safety Warning
1.6.3 Electrical Safety Warning Electrical Safety Warning There are sufficient voltages in this kit to give you a very nasty and harmful shock so be careful when powering on, debugging, and probing around. Please be aware of proper electrical safety. Please contact AudioNote kits via phone or email (audionotekits@rogers.com) to discuss any precautions necessary when building the kit if you feel unsure about what you are doing at any stage of the build.
Page 17: Section 2 - Feet, Iec And, Rocker Switch Installation
Section 2 Feet, IEC, and Rocker Switch Installation Overview In this and the following section we will install the feet, IEC socket, rocker switch, IEC board, and the Choke, as well as make the important initial connections to the Mains transformer and install it in the chassis.
Page 18: Feet Installation
Feet Installation Let's start by installing the 4 rubber feet into the holes in the 4 corners of the chassis — using the hardware provided in the “Feet” bag in the big Hardware bag. Use an M4 Phillips Head screw along with the big washer on the outside of the foot and then a M4 nut and M4 serrated washer against the chassis on the inside of the chassis.
Page 19: Iec And Rocker Switch Installation
IEC and Rocker Switch Installation Now let's install the input AC receptacle (IEC plug) in the rear of the chassis. Use 2 small Phillips Head screws and nuts for the AC receptacle. Here you can see the correct installation of the IEC plug in the rear of the chassis along with the rocker switch.
Page 20: Preparing And Installing The Mains Ground Wire
2.3.1 Preparing and Installing the Mains Ground Wire Referencing the picture below, Cut the Green wire coming out of the Mains Primary to not less than 20 cm". This will be long enough to reach the chassis ground. Strip and tin the end and solder a ground lug to the end. We'll attach it to the chassis a bit later.
Page 21: Iec Pcb Wiring
IEC PCB Wiring 120V and 240V Operation Cut the four remaining wires (White, White-Grey, Black, and Black-Grey) coming out of the Mains Primary to 30 cm. Strip and tin the ends. (You can add some heat shrink if you like.) Connect these four Primary wires to the IEC PCB as shown in the diagram below.
Page 22 120V Operation ONLY Add the two jumpers as shown. (You can use the left over end of the Black Primary wire.) 240V Operation ONLY Add one jumper as shown. (You can use the left over end of the Black Primary wire.) Copyright ©...
Page 23 120V and 240V Operation Referencing the appropriate diagram below (they're identical except for the jumpers you've already installed), complete the IEC/rocker switch wiring as follows: Tin and solder the unprepared ends of the half-prepared Red and Black wires in the IEC bag onto the IEC PCB, as shown.
Page 24: Section 3 - Mains Transformer And Iec Pcb Installation
Section 3 Mains Transformer and IEC PCB Installation The Mains Transformer Primary consists of the standard AC voltage in your area. Secondary supplies the AC voltages (510V, 255V, 12.6, 6.3 and 5.0) needed for the various parts of the amplifier circuit. The following diagram shows the voltages and the color coding of the Primary and Secondary wires.
Page 25: Mains Transformer Installation
3.1 Mains Transformer Installation Let's position the Mains transformer now. It uses 2 rubber strips to isolate it from the chassis. Lay down the two rubber strips so that they are over the correct holes in the chassis — these holes are about 8 cm apart —...
Page 27: Connecting And Mounting The Iec Pcb
Connecting and Mounting the IEC PCB Again, referencing the diagrams below, Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 27...
Page 28 Push the crimped ends of the Red and Black wires coming from the IEC PCB onto the left lugs of the rocker switch, Red on top, Black below. Apply the pressure necessary to position the wires correctly onto the lugs. Using the prepared Red and Black twisted and crimped pair of wires, connect the IEC socket —...
Page 29 Next, let's test these important connections. Using your multimeter's Continuity setting, verify the following: IEC socket ground to chassis ground  IEC socket Neutral to IEC PCB Black-Grey solder tab  IEC Line (Hot) to IEC PCB White Solder tab ...
Page 30: Preparing The Mains Secondary Wires
Preparing the Mains Secondary Wires Finally, let's prepare the Mains Secondary wires for clean routing and, later, the interwiring stage. Cut a 20 cm length of heat shrink and slide over the Blue/White, Grey, and Orange/White wires. Do not use heat to shrink the bundle at this time. Similarly, cut a 23 cm length of heat shrink and slide over the Red and Orange wires.
Page 31: Section 4 - Choke Installation
Section 4 Choke installation Install the choke as shown in the picture below, using the provided M4 hardware. Cut the 2 Black Choke wires to 17 cm and cover with 8 cm of heat shrink. Do not use heat to shrink the bundle at this time.
Page 32: Section 5 -Power Supply Pcb Installation
Section 5 Power Supply PCB Installation Overview In this section we'll be building the Power Supply board. Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 32...
Page 33: Parts List
Parts List The Power Supply PCB will be populated with the parts from the Power Supply bag. Designation Description C1 C2 30uf 600V Square Mundorf Capacitors Black 8-pin Valve Sockets 5AR4 / GZ34 Tubes FB/1A 1A Fast Blow FUSE Fuse Clips Building the Power Supply PCB In the following order, Position and solder the 2 fuse holders.
Page 34 that you're heating both the socket pin and the solder lug. When you're done, examine the connections carefully to make sure there are no cold solder joints; resolder if you're in doubt. Position the 2 square Mundorf 30uf capacitors with the lettering facing the tube sockets and solder them in place.
Page 35: Mounting The Power Supply Pcb
5.3.1 Mounting the Power Supply PCB Next we'll install the four standoffs (from the "Power" bag) for the Power Supply PCB. From the top of the PCB, insert a screw through each of the four holes in the corners of the PCB and attach the standoffs.
Page 36: Power Supply Pcb Interwiring
Power Supply PCB Interwiring We'll now complete most of the Power Supply PCB Interwiring, particularly the wires coming from the Mains Secondary and the Choke. My recommendation is that you route the wires underneath the Power Supply PCB and push the leads up into the PCB; it'll be neater. You should now measure the lengths of all the wires shown in the diagram below to make sure that they are not too long or too short.
Page 37 Secondary Connect the Orange/White wire from the Mains to the lower 5V/6A tab as shown. Secondary Connect the Red wire from the Mains to the upper HT/AC tab as shown. Secondary Connect the Orange wire from the Mains to the lower HT/AC tab as shown. Connect the 2 Black wires from the Choke to the L1/AFC tabs as shown.
Page 38: Section 6 - Ecf80/El84 Pcb Installation
Section 6 ECF80/EL84 PCB Installation Overview This is the large PCB that we will start to populate and verify. This is quite a bit of work but we can take it one step at a time. We'll divide up the board into several sections and take our time! Copyright ©...
Page 39: Building The Ecf80/El84 Pcb
Building the ECF80/EL84 PCB We start with the PCB itself: The ECF80/EL84 PCB will be populated with the parts from the ECF80/EL84 bag. Note There are some component markings on the right side of the board, particularly EC1, EC2, D1, D2, D3, D4, C9 and C10 which are not used.
Page 40: Tube Socket Installation
6.2.1 Tube Socket Installation Designation Description Beige 9-pin Valve Sockets V1A, V1B ECF80 / 6BL8 Tubes V2A, V2B, V3A, V3B EL84 / 6BQ5 Tubes We'll begin by installing the tube sockets. The key is to Use some masking tape to secure the valve base to the board prior to soldering. make sure the valve base is level : if you have a base that is soldered in on an angle then your tube will also lean over! You'll want to solder from the underside of the board.
Page 41: Resistor Installation
6.2.2 Resistor Installation Color Code Designation Description R1-A, R1-B 150K 1/2W R2-A, R2-B 390R R3-A, R3B 100R 1/2W R4-A, R4B 560K 1/2W R5-A, R5-B, R6-A, R6-B R7-A, R7-B 1/2W R8-A, R8-B 1/2W No Color Code R9-A, R9-B, R10-A, R10-B 2.2K 1/2W No Color Code R11-A, R11-B, R12-A, R12-B...
Page 42 Let's start by installing all the resistors correctly and verifying. When you see R1-A — this means that R1 has a value of 150K (for example) and that there is a right and left channel which are designated as R1-A = 150K, R1-B = 150K. I suggest you use an Ohm meter to verify the values of the resistors that you are installing.
Page 43: Capacitor And Diode Installation
When you're done, if you want to double check your connections, here's a way to be absolutely sure: 1. Set your multimeter to the Ohm position. 2. Touch one end to the lead of a resistor above the PCB (not the PCB solder pad to which it's connected).
Page 44 Other capacitors Designation Description C7-A, C7-B 33pf, 500V C8-A, C8-B 39pf, 500V C9-A, C9-B 68pf These caps can be positioned in either orientation. They also may have some unusual markings, but I don't think you'll have too much difficulty figuring them out! Install the non-polarized C7, C8, and C9 capacitors.
Page 45 Congratulations! You've now completed the ECF80/EL84 PCB. Place it aside for the moment. We'll install and wire it when we do the Interwiring section. Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 45...
Page 46: Section 7 - Rca Jacks Installation
Section 7 RCA Jacks Installation Mounting the RCA Jacks At the rear of the chassis let's install the RCA jacks. The two RCA jacks install into one of the three pairs of vertically aligned holes. In our build, we've used the middle set of holes and mounted the Red jack above the Black jack.
Page 47: Section 8 -Attenuator Installation And Rca Jacks Wiring
Section 8 Attenuator Installation and RCA Jacks Wiring There are three steps involved in wiring the signal and ground from the RCA Jacks on the rear of the chassis to the Khozmo attenuators and from there to the ECF80/EL84 PCB. I don't think there's any magic order to these steps.
Page 48 Here's a picture of what we want to do: Let's begin: Take one end of the AN-A cable supplied with your kit and, using your wire clippers or an X- Acto knife, carefully make a small cut between the two halves of the cable so that you can Be careful not to nick the shield;...
Page 49 Next we'll do the other end, which is a bit different. Please follow this closely. Begin, as above by separating the two halves of the cable for 12 cm. For each half, Using your wire strippers set to AWG 10, strip off 3 cm of the yellow outer insulation. Do not cut it off Carefully unravel and pull down the stranded shield wire.
Page 50: Wiring The Attenuators
8.1.2 Wiring the Attenuators Before we begin, take a moment to review the diagram below of the wiring of the Khozmo attenuators. Let's begin by installing the input resistors. Examine the mini PCB on the attenuator carefully, especially the five solder pads. As you can see, the solder pads for the input resistors are only a few millimeters apart and the resistor is much larger.
Page 51 Look at the pictures below: Carefully bend the resistor leads as shown and solder them to the attenuator. You may want to clip just a little bit off the end of each lead to be able to fit them through the holes. Don't take too much off or the leads will not reach the solder pads. I strongly suggest practicing this tricky bending and insertion bit with a small spare resistor first.
Page 52 Next, let's prepare the wires that will go from the Khozmo attenuators to the ECF80/EL84 PCB. Cut two 18 cm Red wires and two 18 cm Black wires. Strip 6 mm off each end, twist them neatly so that there are no dangling strands, but do not tin them. Finally, let's wire the attenuators: we'll use the AN-A cable we prepared in Section 8.1.1, that is, the end without the shield and the four wires we've just prepared.
Page 53: Mounting The Attenuators
8.1.3 Installing the Attenuators Now let's install the two attenuators at the front of the chassis. Mount the attenuators as shown in the picture below, using the supplied hardware. 8.1.4 Wiring the RCA Jacks Referencing the picture-diagram below, look closely at the AN-A cable. We've already wired the ends without the shields to the Khozmo attenuators in the steps above.
Page 54 When working with the RCAs and the AN-A cable I use the following procedure: Tin the RCA ground lead and put a puddle of solder in the center of the RCA  Heat the solder puddle and slide the Red tinned lead into the center of it ...
Page 55: Section 9 - Headphone Jacks Installation
Section 9 Headphone Jacks Installation Mounting the Headphone Jacks At the front of the chassis let's install the headphone jacks. Mount the two headphone jacks as shown in the pictures below, using the supplied Black screws and serrated nut hardware. 9.1.1 Wiring the Headphone Jacks Cut the following lengths of wire: One 8 cm Orange, one 8 cm White, one 8 cm Black...
Page 56 Referencing the following diagram, complete the wiring to the headphone jacks. Start by wiring the jack on the right so that once you've got the wires routed and are sure the lengths are sufficient, you can trim the lengths of the 8 cm wires to the jack on the left a bit if you like. Do not trim the 45 cm wires at this time and do not connect them to the ECF80/EL84 PCB.
Page 57: Section 10 - Output Transformers Installation
Section 10 Output Transformers Installation 10.1 Output Transformers Installation Examine the triple C-Core Output Transformers (OPT-A and OTP-B) closely. You'll see Purple, Blue, and Green wires; these are the OTP Secondary. You'll also see Black, Orange, Yellow, Brown, and Red wires. These are the OTP Primary. Position the Output Transformers as shown below and secure with the supplied hardware.
Page 58: Section 11 - Interwiring
Section 11 Interwiring At this stage of the kit you'll have completed the major tasks of the kit build and we can now look at hooking everything up together — this is considered the Interwiring stage. This guide explains the interwiring – best to zoom in on these slides as necessary to show the details! READ through this section first! 11.1 ECF80/EL84 PCB Interwiring 11.1.1 Mounting the ECF80/EL84 PCB...
Page 59: Power Supply Pcb And Mains To Ecf80/El84 Pcb Interwiring
11.1.3 Power Supply PCB and Mains to ECF80/EL84 PCB Interwiring Using the following wiring diagram: Before you make the following connections adjust the heat shrinks on the Mains Secondary and the Red and Black wires coming from the Power Supply PCB to what you feel will give you the look you're after, and apply heat.
Page 60: Output Transformers To Ecf80/El84 Pcb Interwiring
11.1.4 Output Transformers to ECF80/EL84 PCB Interwiring both Using of the following wiring diagrams: The 8R and COM connections have two wires going to each solder pad, so don't jump ahead. Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 60...
Page 61 Connect the OPT-A/B Secondary Purple wires and the left and right signal wires (White and Orange respectively) coming from the headphone jacks to the 8R solder tabs as shown. Connect the OPT-A/B Secondary Green wires and the left and right ground wires (both Black) Use your multimeter to check that you've got the correct to the COM solder tabs as shown.
Page 62 Notes 1. You'll see that there is an additional Blue Secondary wire on each Output Transformer. These wires are there to allow for a Future Option configuration of the amplifier. For now, just route the two Blue wires between the Output Transformers towards the back of the amplifier, bundle them neatly, cut off the (ragged) bare wire on the ends, and terminate each with a small screw on wire connector.
Page 63: Attenuator Interwiring
11.1.5 Attenuator Interwiring Referencing the diagram below, let's complete the interwiring from the attenuators to the ECF80/EL84 PCB. If you like, you can insert the four wires that will go to the ECF80/EL84 in a short length of heat sink. Copyright ©...
Page 64: Led Installation And Wiring
Connect the Read (2) and Black (2) wires to the ECF80/EL84 PCB as follows: Connect the Red wire coming from the OUT of the left Khozmo attenuator to the IN/P-A on the ECF80/EL84 PCB, as shown above. Connect the Black wire coming from the GND of the left Khozmo attenuator to the GND next to the IN/P-A.
Page 65: Interwiring Chart
11.3 Interwiring Chart Now, use the Interwiring Chart to carefully verify all your connections! If you are in any doubt as to any of the connections, please contact audionotekits@rogers.com. FROM Mains Transformer Orange/White PS PCB 5V/6A Grey PS PCB GND next to 5V/6A Blue/White PS PCB 0/CT Orange...
Page 66 Purple wire to OPT-A Black wire to headphone jack Green wire to OPT-A Black wire to headphone jack Green wire to OPT-B Orange wire to headphone jack Purple wire to OPT-B RED (Channel B) Black wire to OPT-B No Label (Channel B) Orange wire to OPT-B OPT-B (Channel B) Yellow wire to OPT-B...
Page 67: Section 12 - Testing
Section 12 Testing Well done! Your amplifier is built and ready to be tested — take a deep breath... The first thing to do is to check — and check — and check again your work! We won't insert any tubes at this point until we've done some important voltage checks.
Page 68: Power On And Voltage Checks
12.1 Power On and Voltage Checks There are a couple of voltage basics that can really help the cause. There are two types of voltage: DC AC. DC is a constant voltage, for example the High Voltage in a 300B amplifier is typically 425V DC, so when you measure from the high voltage point to any ground in the circuit (even the chassis), you will measure 425V DC.
Page 69: Supply Voltages
12.1.2 Supply Voltages Power on the amplifier and check the following AC voltages: Black Lead Red Lead (Test Point) Voltage PS PCB HT/AC (other pad) 510V AC PS PCB HT/AC (nearest edge to front of chassis) PS PCB 0/CT 255V AC ECF80/EL84 PCB 12V/CT left pad 12.6V AC ECF80/EL84 PCB 12V/CT right pad...
Page 70: Output Tubes Cathode Voltages
12.2.2 Output Tubes Cathode Voltages Finally, if all is well, let's install the line stage and output tubes and make a few remaining voltage checks. ECF80/6BL8 Line Stage Tubes EL84/6BQ5 Output Tubes If you measure 10-12V DC on the cathode of each output tube (test points TP1 TP2 TP3 and TP4 on the ECF80/EL84 PCB) this tells us that all the tubes are operating correctly.
Page 71: Section 13 - Finishing Touches
That's it! Place the cover over the unit and secure it in place as well. You're done! 13.2 System Configuration Options The L4 Headphone Amplifier C-Core has two attenuators and input buffering. Therefore, you can choose to provide it with an input signal directly from a high-level source such as a CD player or streaming device, or from the output of a preamplifier.
Page 72: Section 14 - Final Thoughts
14.3 Tube Rolling 14.3.1 ECF80 and EL84 The sound of the L4 Headphone Amplifier C-Core is both classic and modern. Its characteristic warmth is complemented by a detailed and transparent presentation with gorgeous sonics. Rolling some nice NOS or different new production tubes in the ECF80, EL84, and GZ34 positions will allow you to tailor the sound to your particular preferences.
Page 73: Headphones
14.4 Headphones In order to fully realize the potential of the L4 Headphone Amplifier C-Core, we recommend that you pair it with high quality headphones from manufacturers such as Audeze, Bowers & Wilkins, Focal, HiFiMan, JH Audio, JPS Labs, Sennheiser or Sony, among others. Our experience is that top quality headphones are able to both sort out complex recordings —...
Page 75: Resistor Color Code Reference
You can also find an 'Interactive Resistor Color Code Calculator' on our website (available from the Links page). Copyright © 2019 AudioNote Kits www.AudioNoteKits.com audionotekits@rogers.com Page 75...

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