ANK Legend Monoblock 300B-2A3 Instructions for use

Legend Monoblock 300B–2A3
Parallel SET Amplifier
Construction Manual
Version 3.04, October 2019
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1-613-822-7188

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Table of Contents
Section 1 —Introduction ……………………………………………..………………………….…………………… 5
1.1 About ANK Audio Kits ……………………………………………..…………………………..…………………… 6
1.2 Basic Operation of the Amplifier………………………………….……………………….………..…………… 7
1.3 Schematic ……………………………..…………………………………………………….….…………………… 9
1.4 Equipment ……………………………..……………………………………………………..……………………… 10
1.4.1 Overview of the Kit ………………………………………………………..….……….…………… 10
1.5 Tips and Suggestions …………………………………………………….………….…..………………………… 10
1.5.1 Soldering …………………………………………………….……….….…….……………………… 10
1.5.2 Components ……………………….…………………………….………….…….……………………… 11
1.5.3 Resistor Sizes ……………………………………………….……….……….………….………………… 11
1.5.4 Capacitor Manufacturers and Voltage Ratings …………….…………………………… 11
1.5.5 Electrolytic Capacitors ……………………………………………………….………………………… 11
1.5.6 Diodes ………………………………………….……………………………..………….……………………… 12
1.5.7 Hardware/Mechanical …………………………………………………………….…………………… 12
1.5.8 Wire Stripping and Tinning ……………………………………………….…………………… 12
1.5.9 Wire Color ……………………………………………………..……………….…….………………… 13
1.5.10 Optional Finishing Touches …………………………..………….…….……………………… 13
1.6 Build Process ………………………………………………………………………………..………………..………… 14
1.6.1 Some Good Rules of Thumb for Building Your Amplifier …………………….……… 14
1.6.2 Organization of this Manual …………………………………………………….…..…….…… 14
1.6.3 Electrical Safety Warning …………………………………….………….………..………… 16
Section 2 —Mechanical Assembly ...............................................................................…17
2.1 Overview ……………………………………………………………………………….…..…..………..…….…… 17
2.2 Installing the Rubber Grommets……………………………………………………….…….………..…….…… 18
2.3 Installing the Valve Base …………………………………………………….….……………..…….…… 19
2.4 Installing the Tang Strips ………………………………………………….…….……………..…….…… 21
2.5 Installing the Capacitor Clamp ………………………………………………….….………………..…….…… 23
2.6 Installing the Ceramic Hardwiring Posts …………………………..………………..…….…… 25
2.7 Installing the Filament Supply Board Hardware ….………………………………….…… 27
2.8 Installing the Choke ……………….................................…………....................................…………… 29
2.9 Installing the IEC and Rocker Switch ….................…………....................................…………… 30
Section 3 —The Transformers .................................................................................…32
3.1 Overview ………………………………………………………………………………...…..….………..…….…… 32
3.2 Installing the Mains Transformer ………………………………………….…..….………..…….…… 33
3.3 Installing the Output Transformer ……………………………………..….………………..…….…… 38

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Section 4 —The Power Supply .................................................................................…40
4.1 Overview ………………………………………………………………………….………..…...………..…….…… 40
4.2 Installing the Chassis-Mounted Capacitor ……………………….……...…...………..…….…… 42
4.3 Preparing the Chassis Ground …………………………………………………….…..…...………..…….…… 43
4.4 Wiring the IEC, Rocker Switch, and Mains Transformer ……..…………....….………..…….…… 45
4.5 Installing the Resistors ……………………………………………….………………….......….………..…….…… 47
4.6 Wiring the Chassis-Mounted Capacitor ……………………………….………........…………..…….…… 54
4.7 Connecting the Choke ………………………………………………………….……….………………..…….…… 56
4.8 Initial Mains Secondary Wiring ……………………………………………………..………………..…….…… 57
4.9 Power Supply to Front Insert Plate Wiring …………………....….....………………..…….…… 59
4.10 Connecting the Output Transformer ……………………………….…....….………………..…….…… 60
4.11 Wiring the Rectifier Filaments ……………………..…………………….………..………………..…….…… 61
Section 5 —The Filament Supply Board ....................................................................…63
5.1 Overview ………………………………………….………………………………………..…..………..…….…… 63
5.2 Parts List ………………………………………….………………………………………..…..………..…….…… 65
5.3 Installing the Resistors …………………………….………………………………………..…..………..…….…… 66
5.4 Installing the Capacitors ……………….…………………………………………….………..…….…… 67
5.5 Installing the Bridge Rectifiers ……………….………………………………………...….………..…….…… 67
5.6 Installing the Regulators ……………….………………………………………...….………..…….…… 68
5.7 Connecting the Filament Supply Board ….………………………………………...….………..…….…… 70
Section 6 —The Front Insert Plate ...................................................................… 73
6.1 Overview ………………………………………………………………………….………..….……………….…… 73
6.2 Installing the Valve Bases and the Tag Strip …………………….…………………………….…… 74
6.3 Installing the Jumper Wires ………................................…………….…………………………….…… 76
6.4 Installing the Resistors …………………………………………………………….….……..….………..…….…… 78
6.5 Installing the Capacitors ……………………………………….………….……..….………..…….…… 82
6.6 Additional Front Panel Insert Wiring …………………………….……………..….………..….….…… 84
Section 7 —The IO Connections ................................................................................…86
7.1 Overview ……………………………………………………………..……………………..….………..…….…… 86
7.2 Installing the RCA Input Jack …………………………………..……................…..….………..…….…… 86
7.3 Wiring the RCA Input Jack …………………………………..……................…..….………..…….…… 87
7.4 Mounting the Front Insert Plate ……………………........................……………………………..…….…… 89
7.5 Installing the Speaker Posts ……………………........................……………………………..…….…… 90
7.6 Wiring the Speaker Posts ……………………........................……………………………..…….…… 91

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Section 8 —Wiring Check Lists …………………………………............................................. 92
Section 9 —Testing …………………………..............………………………………………....………….. 95
9.1 Overview ......................................................................................................................................... 95
9.2 Installing the Fuse ......................................................................................................................... 96
9.3 Initial Tests ......................................................................................................................................... 96
9.4 First Power-Up ......................................................................................................................................... 100
9.5 Voltage Tests ......................................................................................................................................... 102
9.6 Sound Check ......................................................................................................................................... 106
9.7 Debugging ......................................................................................................................................... 106
Section 10 —Finishing Touches ……………………..………..…………….…………………….…....………… 107
10.1 Installing the Front Faceplate ………..………………….……..…………..……………………….…………… 107
10.2 Installing the LED ……………………..….………………………..………..……………………...….………… 107
10.3 Installing the Chassis Top ………..….…………………………...........………………………....………… 107
Section 11 —Final Thoughts ……………………..……………………….…………………….…...………… 108
11.1 Congratulations ……………………………………………………………..…………………………………… 108
11.2 Break-in ……………………..…………….…………….…………………………………………….…...………… 109
11.3 Cables …………………………………..…………….…………….…………………………………………….…...………… 109
11.4 Tube Rolling ……………………..…………….…………….…………………………………………….…...………… 110
11.4.1 5U4-G ………..………………………….……..……….……………………..……………………...…………… 110
11.4.2 6SH7 ……………………..…………….……..……….……………………..……………………...…………… 110
11.4.3 300B and 2A3 ……………………..……………………………………………………….…….…………… 110
11.5 Thanks ……………………..…………………………………………………..……………….………….………………….… 111
Appendix ……………………………………………..……………………………………………………...……….……….…… 112
Resistor Color Code Reference …………….……………………………………………………….…..…….…… 113
Mains Wiring for 240V ……………………….…………………………………………….…..………………….…… 114

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Section 1
Introduction
Thanks for purchasing the ANK Audio Kits Legend Monoblock 300B-2A3 Parallel SET Amplifier. Our
goal is to provide you with the highest quality kit that you will build from scratch with these
instructions.
This is very high end and sophisticated piece of audio equipment that will surely become a showpiece
of your sound system. We're excited that you have chosen to join us in enjoying and appreciating
superb audio and we've created this manual to help guide you through each step of the assembly
process with as much detail and clarity as possible. To facilitate the build process, the manual has
been divided into a number of sections, each focusing on a separate aspect of the system: follow the
sections in order and we guarantee you not only a problem-free experience, but a pleasant time
doing so. If you are new to building kits, or if at any time you feel as though you need help or advice,
feel free to contact us and we will do whatever it takes to get you on the right track.

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1.1 About ANK Audio Kits
Audio Note (UK) started out in the early '90s developing several DIY audio kits while they were
building up their finished product business. DIY Audio has a long history and it was an opportunity
for knowledgeable customers to take advantage of world class designs and components. Audio Note
(UK) was focused on using the very finest materials and components custom-made to their
specifications, across their entire product line —from custom film and electrolytic capacitors to
tantalum resistors, transformers, binding posts, wires, etc. The Kit1 300B single-ended integrated
amplifier was born during development of the Meishu and it proved to be extremely popular
worldwide. The ANKit business was born!
As the finished product business and dealer network started to flourish, Audio Note (UK) eventually
moved the kit business off into a separate division; thus, in 2004, Audio Note Kits started up and was
supported by a website so that customers not located near Audio Note (UK) dealers could order kits
and have them shipped direct. Kit development continued in earnest during the 2000s with
development assisted by Audio Note (UK) engineering. Audio Note (UK) parts were used throughout
the kits, depending on the various levels and budgets. By 2013, ANK Audio Kits (as it came to be
called) had developed a wide product range covering all areas of two channel audio: a single-ended
300B product line, an EL34 Class AB and single-ended product line, digital to analog converters, pre-
amplifiers, phono stages, and Audio Note (UK) speaker kits. The end result today is that customers
worldwide with DIY skills can now build an entire high end audio system to their liking. With the
introduction of higher product levels in 2013 and the release of the Level 5 Mentor Pre-amplifier and
the DAC 5.1 Signature, some customers wanted these high end products assembled by a professional
builder. As a result, ANK Audio Kits began offering this service for some 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.
We believe and hope that you will have a great experience building your kit and we look forward to
hearing from you about your experience.
Regards,
Brian Smith —Director ANK Audio Kits

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1.2 Basic Operation of the Amplifier
ANK Audio Kits is proud to present the Legend Monoblock 300B-2A3 Parallel SET Amplifier. As
anyone who has ever heard the transcendent musicality of a single-ended amplifier will tell you,
there is something very special about the music that flows from (relatively) simple, classic Class A
triode circuits. Perhaps it's the absence of crossover distortion, perhaps it's the gorgeous midband
reproduction, perhaps it's the zero feedback design, perhaps it's the organic (even desirable)
expressiveness of the second harmonic; more likely it's all of this and more.
ANK Audio Kits and SET amplifiers go a long way back, right to the beginning in fact, with our Kit1
300B, which has had successive and successful anniversary editions. It's no surprise then that these
300B Single and Parallel SET monoblocks are simply awesome! A pair of these power amplifiers are a
perfect mate for the Mentor pre-amplifier and a path to truly exceptional audio enjoyment.
Design Elements
The Legend Monoblock 300B-2A3 Parallel Amplifier is a true high-end amplifier, a beautiful
expression of single-ended amplification, reserved for the discerning audiophile.
The Legend series monoblock single-ended amplifiers employ a 6SH7 driver tube —selected by Andy
Grove for reasons related to the input impedance and sensitivity in mating with a pre-amplifier —
wired in a pentode configuration to drive a Parallel or Single triode 300B or 2A3 tube. It's the
ultimate in configurability for anyone serious about SET amplification and is a class amplifier —a
Legend in its own right! With 2 special Mains transformers, the T-194 and T-195, the following 4
options are available:
Option 1 Single 2A3 amplification, 3.5W single-ended
Option 2 Parallel 2A3 amplification, 7W single-ended
Option 3 Single 300B amplification, 8.5W single-ended
Option 4 Parallel 300B amplification, 18-20W single-ended
The Legend amplifiers deliver that gorgeous zero feedback single-ended triode sound. Simplicity is
the key to the circuit of the amplifiers which are targeted at higher efficiency speakers. They
provide remarkable sound quality to rival the best of SET amplifiers, yet they do this at a real world
price. A remarkable achievement!
They are a pure power amplifier with approximately 2V sensitivity and are ideal when mated with
our L2 or L3 pre-amplifiers. Among its high-end features are a classic 5U4-G rectifier tube, which
smoothes the AC for the Power Supply; DC filaments; a large 300ma Power Supply Choke installed
inside the chassis —assuring dead quiet operation; high quality black Teflon 4- and 8-pin valve
bases; and Audio Note (UK) hardwire tag strips.

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Here’s a pair of completed Legend Monoblock 300B-2A3 SET Amplifiers

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1.3 Schematic1
1From time to time revisions and upgrades to products result in circuit changes that are not always reflected
in manuals. If you encounter any issues with how this schematic relates to your build that need clarifying,
contact us at [e-mail].

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1.4 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)
1.4.1 Overview of the Kit
In your kit you will find a series of kit bags containing all the hardware, wire, and parts for the
associated sections of the amplifier. See the Parts List files on the disk to match up the parts in the
kit bags with the lists. There is also a Master list for the kit.
1.5 Tips and Suggestions
We have learned a lot about kit building over the last decade from our customers and I'd like to share
some tips with you to ensure a successful project. Please read through this section thoroughly, it will
give you a good idea of what's ahead and help ensure your success!
1.5.1 Soldering
We highly recommend using lead-based solder with some silver content2on the build. You should use
lead-free ONLY if you are experienced using it and confident. Lead-free solder requires a higher
melting temperature and thus is more difficult to use. We don’t recommend lead-free solder for first-
time builders.
We suggest that you practice your soldering before starting on the kit. Feel free to request practice
parts with your kit so that you can practice tinning wires and making nice solder joints. The key is a
good soldering station with a sponge, the right temperature, a good size tip, and experience;
remember, tips can wear out so make sure your tip is working. (You can also check out YouTube
videos for soldering lessons and examples.) The solder should flow freely; if it’s forming balls then
there is likely a problem with the tip, the temperature, or (sometimes) the surface. Feel free to
contact us for help!
2For example, WBT-0800.