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Page 75

Section 11

Testing

11.1 Overview

It's time do to some testing to make sure that amplifier has been correctly wired and that things are
working the way they're supposed to.

Our plan is as follows:



With no tubes installed, power the amplifier on to verify that the fuse does not blow.



Make some basic DC measurements: for example, checking the 5V filaments of the 300B.



Install the 6SH7 and the 300B, then power on to make sure that the 300B glows.



Install the 5U4G rectifier and measure a number of key AC and DC voltages.



Test with a 'cheap' speaker for sonics and hum. If all is well, play in a proper system, enjoy!

Before testing, it's a good idea to blow some air into the unit and make sure that there are no small
pieces of wire or solder floating around.

Summary of Contents for 300B

Page 1: ...Interstage Monoblock 300B SET Amplifier Construction Manual Version 3 05 August 2019 audionotekits rogers com 1 613 822 7188 ...

Page 2: ... Tinning 12 1 5 9 Wire Color 13 1 5 10 Optional Finishing Touches 13 1 6 Build Process 13 1 6 1 Some Good Rules of Thumb for Building Your Amplifier 13 1 6 2 Organization of this Manual 14 1 6 3 Electrical Safety Warning 17 Section 2 Mechanical Assembly 18 2 1 Overview 18 2 2 Installing the Rubber Grommets 19 2 3 Installing the Clamps 20 2 4 Installing the Valve Base 21 2 5 Installing the Ceramic ...

Page 3: ...ply Board Installation 54 5 1 Overview 54 5 2 Parts List 55 5 3 Installing the Resistors 55 5 4 Installing the Capacitors 56 5 5 Installing the Bridge Rectifier 57 5 6 Installing the Regulator 58 Section 6 Filament Supply Board Interwiring 59 6 1 Overview 59 Section 7 Front Insert Plate Wiring 61 7 1 Overview 61 7 2 Installing the Valve Bases and the Tag Strip 61 7 3 Installing the Resistors 62 7 ...

Page 4: ...sts 78 11 5 1 HT and 300B Voltages 79 11 5 2 6SH7 Voltage 80 11 5 3 Power Supply Voltages 80 11 6 Sound Check 81 11 7 Debugging 82 Section 12 Finishing Touches 83 12 1 Installing the Front Faceplate 83 12 2 Installing the LED 83 12 3 Installing the Chassis Top 83 Section 13 Final Thoughts 84 13 1 Congratulations 84 13 2 Cables 84 13 3 Tube Rolling 85 13 3 1 5U4G 85 13 3 2 6SH7 85 13 3 3 300B 85 13...

Page 5: ... 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 on...

Page 6: ...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 classAB and single ended product line digital to analog convert...

Page 7: ...amplifiers Importantly rather than an additional tube driver stage the interstage transformer takes over this task for ultimate authority providing a level of realism and detail that you may not have experienced and driving the 300B triode in single ended mode The triode then drives the output transformer OP 300 Audio Note UK s Peter Qvortrup has underscored the significance of interstage transfor...

Page 8: ...igh gloss clear coating so that it is protected from scratches and will never change color It has a new Mains transformer T 195 and uses the classic 5U4G B rectifier tube and the latest Mundorf MLytic 4 pole capacitor technology to smooth the AC power and the DC filaments and a substantial Choke CH 170 assure dead quiet operation Other amplifier features include the 6SH7 input tube which was selec...

Page 9: ... Page 9 1 3 Schematic1 1 From 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 audionotekits rogers com ...

Page 10: ...ughly 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 content2 on 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 build...

Page 11: ...rent at times With regard to voltage ratings normally the voltage rating of the supplied capacitors will be exactly what you see on the parts lists Occasionally a part may be supplied with a higher voltage Think nothing of it 1 5 5 Electrolytic Capacitors For those who have not built a piece of electronics before here is a little lesson on capacitors There are basically two types of capacitors tha...

Page 12: ... a transformer So if you are asked to use an M3 16mm CSK screw this is an M3 size obviously which is a thinner shaft diameter than an M4 16mm is the length of the shaft and the head type is CSK which is a countersunk or flat head screw Once you have the screws mastered look at the matching nuts such as M4 nut or M3 nut and corresponding washers Standoffs are common in the kits again they are eithe...

Page 13: ...lders who want to incorporate some of these finishing touches should feel free to do so While we don t officially support or supply parts for these optional enhancements there s no reason why you couldn t or shouldn t do them if you want to and feel that you can handle them Without getting into the details you re on your own here what you ll want to get hold of are heatshrink to bundle wires cable...

Page 14: ...to the wiring We provide easy to follow step by step assembly and wiring instructions and we prepare the parts you ll need in 15 separate sections with all IEC cabling and twisted wire prepared for you ahead of time making it easy to work through each build stage The result we hope that your kit is a joy to build We ve divided the build and the manual into the following sections 1 Introduction 2 M...

Page 15: ... 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 top and bottom as shown below Top Side Bottom Side ...

Page 16: ...t each graphic slide shows only the wiring to be done in that sub section and not to have information overload may not show wiring previously completed The overlaid routing of all the point to point wiring underscores why it s a good to go slowly think carefully about wire length and routing and use like heatshrink and cable ties to keep things neat and tidy as in the picture below ...

Page 17: ... safety 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 contact ANK Audio 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 18: ...Mechanical Assembly 2 1 Overview In this section we will prepare the mechanical aspects of the kit mostly on the underside of the chassis Let s start with the chassis and install the rubber grommets 35mm clamps 8 pin valve base ceramic posts IEC and Rocker Switch Mills 40R resistor Hex standoffs ...

Page 19: ...2 Installing the Rubber Grommets You ll find 3 large and 4 small grommets in your kit bag Install the grommets in chassis Be careful not to use a sharp object to push them in just use your hands and take your time You can push them from the underside of the chassis if you find that easier ...

Page 20: ...ling the Clamps Next install the 3 35mm clamps that will hold the power supply capacitors Position these under the chassis as shown and secure from the top with the M3 10m black flat or countersunk screws Here is the view from the underside of the chassis and the view from the top of the chassis ...

Page 21: ...e can install the Black 8 pin valve base for the rectifier tube You can see the valve base in the top left corner of the picture below Use the Black ring on the underside of the chassis to secure the valve base into position Ensure that the notch on the inside of the valve base is pointing toward the front of the chassis ...

Page 22: ... rogers com Page 22 2 5 Installing the Ceramic Posts The next picture shows the 10 position ceramic posts mounted into position Use 4 6mm steel M3 countersunk flat screws to mount the posts on the underside of the chassis as shown Here are the posts actually mounted ...

Page 23: ...e below for the correct orientation 3 Install the Rocker Switch which just snaps into position Use M3 10mm CSK screws to Install the IEC socket it can mount from inside the chassis or from the outside 3 Of course the orientation isn t critical as long as the wiring is done correctly but the orientation that is shown is what you ll see in the rest of the pictures and graphics in the manual so it s ...

Page 24: ...dio Kits www AudioNoteKits com audionotekits rogers com Page 24 2 7 Installing the Mills Resistor Position the 40 ohm Gold Mills resistor as shown below and secure with 2 x 10mm Black counter sunk screws from top of chassis ...

Page 25: ...tall to do We must position 4 10mm M3 hex standoffs which will allow us to mount the filament board later on you ll find them in your hardware bag labeled FILAMENT These 4 hex standoffs are located to the right of 35mm clamps Use these standoffs and screws and install them in the chassis as shown below Here s another view from the top of the chassis ...

Page 27: ...erview In this section we will install the transformers We have 4 transformers to mount T 195 Mains Power Transformer CH 170 Choke for the Power Supply IN 500 Interstage transformer OP 300 SET 300B Output transformer It s a good idea to read through this whole section prior to starting to so you have a good idea of what is coming ...

Page 28: ...ree large grommets are located The side with the White Black and Green wires is the Primary and positions to the single grommet side the other side with Red Orange Blue and other color wires is the Secondary and positions to the two grommet side Position the transformer upside down and beside the chassis as shown above Lay down the two rubber strips from your kit bag onto the chassis Start feeding...

Page 29: ...stretch way over to the other hole Start feeding the wires once you have made this distinction While the Primary wires can be threaded through the grommet hole quite easily the Secondary wires will need a little help we suggest you give them a light spray with WD 40 so that they can slide through the grommet hole a little easier Once all the wires are fed through you can use a cloth to wipe off an...

Page 30: ...You can do it alone but it would nt hurt to have a second set of hands for this next bit You will probably have to re position the rubber strips back under the chassis as you continue to move the transformer into position this is the toughest of the four so take your time and be patient ...

Page 31: ... 31 Here is the transformer positioned Line up the transformer as shown above and using the M4 16mm pan head screws and washers secure it into position The washer goes on the top of the chassis and the M4 serrated washer on the underside of the chassis Here a view from the underside ...

Page 32: ...9 ANK Audio Kits www AudioNoteKits com audionotekits rogers com Page 32 The picture below shows the position that we will be working on for most of the kit Well done Things should get a bit easier from this point on ...

Page 33: ...s com Page 33 3 3 Installing the Choke Now let s attach the CH 170 Choke to the chassis Feed the two Black wires through the grommet hole and then use the M4 Pan 10mm screws to secure it into place Below you can see the Choke mounted and the next transformer being readied ...

Page 34: ...com audionotekits rogers com Page 34 3 4 Installing the Interstage Transformer The IN 500 Interstage Transformer is the next to be installed Feed the wires through the grommet hole as shown and then use the M4 Pan 10mm screws to secure it into place ...

Page 35: ...ubilier 30uf 600V capacitor non polarized Mundorf MLytic 100 100 450V capacitor two capacitors in one Use the M3 16mm pan head screws and nuts to tighten the capacitors into position Make sure all the capacitors are flush where they meet the chassis as you can see they are all slightly different heights The 35mm clamps are a bit tight but you should be able to secure the caps into position as show...

Page 36: ...ght 2019 ANK Audio Kits www AudioNoteKits com audionotekits rogers com Page 36 Here is the bottom view line them up as you see in the picture and the wiring graphic below The middle capacitor is non polarized ...

Page 37: ...and Black input Primary wires go through the hole nearest the front of the chassis The Green Blue and Purple output Secondary wires want to be closest to the capacitors Here is the position of the Output Transformer Secure the Output Transformer as shown above Phew Congratulations on completing the Transformer installation section ...

Page 39: ...ers we ll position the amplifier as shown below and start working on the internal wiring of the Power Supply This is basically the entire part of the chassis that you see here As we move forward with the wiring there will be pictures and graphics in the manual to guide you There are also higher definition pictures and graphics you can refer to in the separate Interstage Wiring Guide in pdf format ...

Page 40: ...ice build that might serve as a guide Note how the wires are grouped bound with cable ties routed in a thoughtful and neat manner It s not only beautiful but should the need ever arise it will make troubleshooting so much easier Here s a picture of the underside of a nice parallel Legend build there are circuit differences between this and the Interstage 300B but there s enough similarity to make ...

Page 41: ...wist the Mains transformer Secondary wires together in groups according to how they are going to be used Here s how the Mains wires are colored So for example twist together the Orange wires of the HT the Grey wires of the 6SH7 Filament the center tap CT wires etc This will help keep us organized as we proceed ...

Page 42: ...ound Our first task is to take the Green wire from the Mains Primary and connect it to the Chassis Ground the unpainted Mains transformer screw Extend the wire past the Chassis Ground then strip and tin the wire Add a lug to the tinned wire and then solder the lug onto the wire Do this by adding solder through the front of the lug as shown below ...

Page 43: ...mped end to the GND post of the IEC socket as shown below Take the following 3 wires and position them on the Chassis Ground The Green wire from the Mains that you added a lug to above The lug end of the wire now attached to the IEC GND The other prepared Green wire with just a lug on it Tin the other end now it will be used later for the Power Supply Ground Add a nut and gently tighten We may be ...

Page 45: ...ins Let s have a look at how we re going to do this We ve provided a number of pre made cables and parts for this section to make it easier and neater 2 crimps Heatshrink Red Black twisted cable with crimps For 120 V operation take the twisted White White Grey and twisted Black Black Grey pairs of wires coming from the Mains ...

Page 46: ...nd make sure the solder takes such that the solder is shiny and the wire has accepted the solder Cut these wires5 strip the ends off twist the two ends together tin them add a crimp to the end solder the wires onto the crimp and then install the heatshrink Similarly prepare the Black Black Grey pair Push the crimped White White Grey and Black Black Grey Mains Primary wires that you ve just prepare...

Page 47: ... put heatshrink on the ends so that they do not interfere with anything else Connect the Orange wires to pins 4 and 6 of the 8 pin valve base as shown below It doesn t matter which Orange wire connects to which pin as it s the AC HT input to the 5U4G rectifier tube Similarly put heatshrink on the ends of the Brown wires and connect them to pins 2 and 8 of the 8 pin valve base as shown below Again ...

Page 48: ...t solder resistors or wires to the ceramic posts and capacitors until specified as in a number of instances we ll be adding more wires to them and it s neater to solder more than one wire to a ceramic post or a capacitor lug at the same time In this section then connect means position the wire and we ve indicated when to solder But if you prefer you could solder the first connection and then add a...

Page 49: ...the current supply and thus not allowing any critical circuitry to get damaged Once the resistors are physically installed we ll make some connections on the ceramic posts and add a couple of capacitors Use the following graphic as you follow the steps below Position the 103J 10nf non polarized capacitor across the 100R resistor Position the 10uf 160V electrolytic capacitor across the 47K resistor...

Page 50: ...wire from the Mains Secondary to the left end of the 40R 40 ohm Gold Mills chassis mounted resistor as shown above Position the Brown White wire from the Mains Secondary onto the NEGATIVE terminal of the 30uf 600V chassis mounted capacitor as shown above Don t solder this yet Connect the Blue White wire from the Mains Secondary to the left end of the 47K resistor and solder the connections as show...

Page 51: ...ter to the POSITIVE terminal of the 30uf 600V don t solder this connection yet and the other to the POSITIVE terminal of the input IN section of the 220uf 450V electrolytic capacitors as shown above Solder this connection Let s review what we ve done so far in addition to the Choke 6 A choke is basically one long piece of wire wrapped around a core in order to slow down any AC movement They are us...

Page 53: ...URING THE WIRE USING SOME STRING OF THE SAME LENGTH TO LAY IT OUT ADJUST THE LENGTH AS NECCESARY ALWAYS ALLOW SOME EXTRA THEN CUT TO LENGTH OR DON T CUT IT UNTIL YOU VE SOLDERED ONE END AND ARE READY TO SOLDER THE OTHER END THEN CUT IT TO LENGTH It can be a challenge to do this complex wiring neatly but here s a picture of how it can look if you spend the time and show the patience necessary to ac...

Page 54: ...re and solder the two of them together to the capacitor as shown above Connect and solder the other end of the Black wire added in the previous step to unused right side of the 100R in the ceramic posts Connect and solder one end of a Red wire from the upper POSITIVE terminal of the 100uf 100uf capacitors to the left end of the 15K resistor in the second position of the ceramic posts Solder the co...

Page 55: ...lation 5 1 Overview In this section we will be populating the Filament Supply PCB This board will take the 7V AC voltage from the Mains Secondary and DC regulate it down to 5V which will be used to supply the 300B filaments Filament Supply board7 7 The board shown in for the parallel variant We will populate only half of it ...

Page 56: ... it s shortened to 2K7 Another example like this is the 1M resistor which is 1 Mega ohms Use an ohmmeter to measure each resistor to verify its correct value There s a resistor calculator chart on the audionotekits com website and we ve included a chart in Appendix A 1 It s a good idea to orient your resistors so that the color codes can be read from left to right it makes it easier to spot any is...

Page 57: ... Install the 100R Resistor at R2 5 4 Installing the Capacitors We ll start with the electrolytic capacitors These are the type of capacitors like for example the 4700uf 16V capacitor at C1 which has a stripe down one side You ll remember from the Introduction to the manual that the stripe denotes the NEGATIVE side On the board you ll see a sign which denotes the POSITIVE side Be sure to align the ...

Page 58: ...g the Bridge Rectifier The Bridge Rectifier accepts AC voltage and generates a DC voltage which will be used to create the DC filament voltages You ll see a notch on the Bridge Rectifier part number KBU6J match the notch with the POSITIVE stencil on the board Install the KBU6J Bridge Rectifier at B1 ...

Page 59: ...or pins and the heatsink pins in the same direction Make sure that the regulator is straight by doing the final tightening of the screw while holding the regular and heatsink in position on the board where it will go Insert the regulator and heatsink into the board at IC1 as shown in the picture below and on the next page Solder the 3 pin regulator and the heatsink from underneath the board Once t...

Page 60: ...ilament Supply board These supply the 7V needed by the 300B tube We recommend inserting the wires from underneath the board soldering on the underside and the top then cutting off the excess wire Referencing the graphic above and on the next page Tie off the Black Green and Purple wires We won t be using them they re used for the parallel 300B build Connect the Green Yellow and Black wires from th...

Page 61: ...f the Filament Supply board Next we ll connect one end of each of 2 wires that will supply 5V DC to the Front Insert Plate Connect one end of a Red wire to the DC 1 tab as shown below Connect one end of a Black wire to the Gnd tab as shown below This completes the Filament Supply Board Interwiring section ...

Page 62: ...r plate will help it retain its shine 7 2 Installing the Valve Bases and the Tag Strip Quantity Description 1 6SH7 tube 1 300B tube 1 CMC Black Teflon 8 pin Valve Base 1 CMC Black Teflon 4 pin Valve Base 1 8 position Tag Strip Let s begin by installing the valve bases the 6SH7 and 300B positioning is up to you You can work on the insert plate outside of the Monoblocks and then when we get to a cer...

Page 63: ...install the 9W Ohmite 1K5 Cathode8 power resistors Take your time and carefully wrap the leads as shown Don t cut the lead you want to wrap too short Similarly install the 1K0 1 2W AN tantalum resistor Again take your time and do a neat job 8 We re going to label the pin that is directly connect to the power resistors as the Cathode That will mean that the Cathode is Pin 4 It s unusual and has to ...

Page 64: ...ic Capacitors Referencing the graphic below note that each tag of the tag strip is lettered and that the NEGATIVE lead of each capacitor is indicated by the stripe Connect the NEGATIVE lead of the 470uf 16V Elna Cerafine Electrolytic capacitor to Tag D Connect the other POSITIVE lead to Tag E Connect the POSITIVE lead of the 220uf 100V Elna Cerafine Electrolytic capacitor to Tag G Connect the othe...

Page 65: ...unting the Front Insert Plate and Further Wiring At this point we ll want to mount the Front Insert Plate to the chassis to make the connections to the front input RCA jack and the remaining interstage components And we ll complete some additional the Front Insert Panel interstage wiring by adding several Ground and filament wires and another connection to the 6SH7 Referencing the graphic below ...

Page 66: ...ire between Pin 4 on the 300B and Tag G Connect the 2 Grey wires coming from the Mains Secondary to Pins 2 and 7 of the 6SH7 base Connect a Black wire from Pin 3 on the 6SH7 to Tag E And finally referencing the graphic below Connect a Black 300B Ground wire coming from position 7 8 9 of the ceramic posts to Tag H Connect the Green or Black 6SH7 Ground wire coming from position 7 8 9 of the ceramic...

Page 67: ... are 4 wires Black Red White and Blue coming from the Interstage transformer grommet Referencing the graphic below Connect the Black wire coming from the Interstage transformer grommet to position 1 D on the ceramic post Connect the Red wire coming from the Interstage transformer grommet to pin 8 of the 6SH7 valve base Connect the White wire coming from the Interstage transformer grommet to Tag C ...

Page 68: ...e chassis from the outside The white insulating washer with the raised ring facing inwards into the hole The RCA jack Attach from the inside of the chassis onto the protruding jack The other white insulating washer The ground lug The nut don t immediately tighten this more than one or two turns Bend the ground lug up about 30 degrees and position at about 2 o clock Make sure it is away from the ch...

Page 69: ...ts rogers com Page 69 9 3 Wiring the RCA Input Jack Quantity Description 1 100K 2W AN Tantalum Resistor 1 1K 2W AN Tantalum Resistor 1 330R 1 2W AN Tantalum Resistor 1 100R 2W AN Tantalum Resistor Now we ll add the input resistors as shown in the following graphic ...

Page 70: ...easily Measure the lengths of the Red and Black wires that you ll need to make the connections Allow a little extra Tin the ends of the Red and Black wires Connect a 100R 2W resistor on the 6SH7 valve base between pins 6 and 8 Wrap the ends of the resistor around the pins to secure it Connect the other end of the 1K resistor to pin 4 of the 6SH7 valve base Connect the other end of the 100K resisto...

Page 71: ...s on the Secondary Green is Ground Blue is the 4 ohm tap Purple is the 8 ohm tap 8 ohm Speaker Wiring Connect the Purple wire to the Red speaker post Connect the Green wire to the Black speaker post Cut the end of the Blue wire cleanly and cover it with a small plastic wire connector 4 ohm Speaker Wiring not shown Connect the Blue wire to the Red speaker post Connect the Green wire to the Black sp...

Page 72: ...om Mains Secondary Pin 8 100R resistor to Pin 6 Red Wire from Interstage Secondary 300B Pin 1 Red filament wire from Filament Supply board Pin 2 Red wire from O P transformer Primary Pin 3 1K0 resistor to Tag F Pin 4 Black filament wire from Filament Supply board Black wire to Tag G 2 x 1K5 resistors from Tag H 5U4G Pin 1 Not connected Pin 2 Brown filament wire from Mains Secondary Pin 3 Not conne...

Page 73: ...tor Mains Secondary Blue White CT POSITIVE of 10uf 160V capacitor Position 10 Green wire to Chassis Ground 100R resistor 103J capacitor Tag Strip Tag A Wire to Tag H Blue wire from Interstage Secondary Tag B Not connected Tag C Wire to Tag F White wire from Interstage Secondary Tag D 470uf 16V NEGATIVE 330R resistor to 6SH7 Pin 3 Green wire to Power Supply posts right side near bottom 100K resisto...

Page 74: ...ot connected Position 5 Not connected Position 6 330K resistor Wire to Right Side Position 2 Red wire to POSITIVE of the output OUT section of the 220uf capacitor Position 7 Wire to Right Side Position 8 Position 8 Wire to Right Side Position 9 Green wire to Tag D and Black wire to Tag H Position 9 Wire to Right Side Position 8 Black wire to NEGATIVE of 100 100uf capacitor NEGATIVE of 10uf 160V ca...

Page 75: ...amplifier on to verify that the fuse does not blow Make some basic DC measurements for example checking the 5V filaments of the 300B Install the 6SH7 and the 300B then power on to make sure that the 300B glows Install the 5U4G rectifier and measure a number of key AC and DC voltages Test with a cheap speaker for sonics and hum If all is well play in a proper system enjoy Before testing it s a good...

Page 76: ...g use a screwdriver a flat edge or your fingers to pull it out you ll need to squeeze it to completely remove it Install the fuse in the small plastic fuse holder and insert it into the IEC You can ignore any lettering like 240V only there is only one fuse holder type for all world voltages Turn the amplifier on If the fuse does not blow continue to the next step If it does jump ahead to Debugging...

Page 77: ...probe to each side of this resistor to check its resistance you should see something close to 40 ohms Now let s have a look at the Chassis Ground an important point in the testing process In the picture below10 I m touching the Black test probe of my multimeter to the Chassis Ground right next to the 40R resistor The Chassis Ground is the universal ground point in the amplifier with the Black lead...

Page 78: ...e turn on procedure carefully DO NOT AT ANY TIME ONLY INSTALL THE 5U4G TUBE WITHOUT ANY OTHER TUBES SUCH AS THE 300B INSTALLED The reason for this is that the 5U4G tube is counting on having a specific load to drive If the 5U4G is used without other tubes installed then the amplifier will see significantly higher DC voltages close to 600V which can overextend the Power Supply capacitors You could ...

Page 79: ...e 6SH7 tube is keyed and you need to match up the notch on the 8 pin valve base with the tube base Make sure you don t mix it up with the 5U4G tube which is also an 8 pin valve base tube The 300B tube can only be installed one way in the 4 pin valve base Tubes Installed At This Point 6SH7 and 300B Turn the amplifier on After a few seconds the 300B should begin to glow Turn the amplifier off If all...

Page 80: ...ad Approximate Reading DC Chassis Ground Anode Pin 2 of 300B 400V 5 The first measurement is the HT voltage on the Anode Pin 2 of the 300B the Anode of the 300B is the pin with a Red wire connected to it from the Output transformer It s a good idea to get your schematic out and check the location that you are measuring Pin 2 The measurement will be in the 400V DC range it could be higher or lower ...

Page 81: ...d about 160V DC If the voltage is high here say over 220V then contact us 11 5 3 Power Supply Voltages Let s measure the output of the Power Supply after the last 15K resistor We should see about 166V DC Then check the other side of the 15K resistor we should see about 302V DC Next measure the voltage at input to the 15K resistors we should see 440V Multimeter Setting Black Lead Red Lead Approxima...

Page 82: ...4G Pin 2 5U4G Pin 8 5V AC Well done if all these voltages are good Let s move on to the sound check 11 6 Sound Check Now that we have an amplifier with correct DC conditions it s time to see if we can get some sound We recommend hooking up your CD player or computer to the input and a pair of cheap speakers and pass an audio signal through the amplifier to verify that it is working correctly When ...

Page 83: ...lace to start is by doing some basic checks Make sure you have a signal entering the amplifier Make sure that your speakers are connected Recheck the wiring in the Power Supply and Front Insert Plate If that doesn t fix things contact ANK Audio Kits at audionotekits rogers com We ll figure things out Please have a few telling digital pictures ready to share with us ...

Page 84: ...d back of the front faceplate Install the front faceplate using four Black M4 CSK flat head screws 12 2 Installing the LED Carefully trim the LED leads so that they are not exposed It s a good idea to trim the NEGATIVE lead a bit shorter than the POSITIVE lead so that if you need to remove the LED later for any reason you ll know which is the POSITIVE lead the longer lead and will be able to reins...

Page 85: ... Thoughts 13 1 Congratulations If you ve made it to this point then CONGRATULATIONS you are ready to insert your amplifier into your real system sit back and enjoy the music 13 2 Cables In our experience a high quality power cable and good interconnects should make a noticeable improvement to the sound ...

Page 86: ...t the one to have is the 274A or 274B Western Electric rectifier if you can find one and have 1 000 or so burning a hole in your pocket In any case do not substitute any other 5V rectifier for the 5U4G B type for which this amplifier was designed there are some significant differences between a 5U4G B and other rectifiers with respect to voltage drop and current specifications and the result of a ...

Page 87: ...nt were there any errors in the manual or instructions parts lists etc Your ideas regarding greater clarity or tweaks will also be truly appreciated If you have some suggestions that you feel would help other kit builders please also let us know We can put them on a support page for other users We d also like to see some great pictures of your build process or your final build We can post them on ...

Page 89: ...Copyright 2019 ANK Audio Kits www AudioNoteKits com audionotekits rogers com Page 89 You can also find an Interactive Resistor Color Code Calculator on our website available from the Links page ...

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