Caledonian Audio 6BM8/ECL82 SE User manual

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Version!3.0!
Caledonian!Audio!
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Version!
Date!
Changes!
0.1!
1st!of!May!2018!
Initial!creation!
1.0!
1st!of!Nov!2018!
Reviewed!and!accepted!
2.0!
4th!of!June!2019!
Updated!against!a!review!
3.0!
25th!of!October!2019!
Now! for! 6BM8! PCB!
Version!C!for!MKII!
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The! work!conducted! here! deals! with! high-level!voltages.! It! should! only! be!
conducted!by!:,*&9M9#N!personals.!
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Please!be!aware!that!O*P*O9A?>"!can!hold!charges!for!a!long!time!and!they!should!
be!properly!N9"OQ*>R#N!prior!to!any!work.!
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The!6.3V!or!12V!terminals!are!rated!in!relation!to!another!voltage!reference!level,!
but! in! reality,! the! potential! difference! between! the! 12V! (as! an! example)! and!
ground!earth!might!be!anywhere!up!to!400V.!So,!please!treat!any!6.3V!or!12V!
terminals!with!#SA>#$#!care.!
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Introduction!...........................................................................................................................................!7!
Assembly!Instructions!..................................................................................................................!8!
PCBs!Preparation!.................................................................................................................................!9!
Heater Filament PCB!......................................................................................................................!9!
Main!Power!Supply!PCB!...........................................................................................................!11!
Stuffing!the!Amplifier!PCBs!.....................................................................................................!18!
Socket!Soldering!......................................................................................................................!18!
Components!Soldering!.........................................................................................................!20!
Mounting!Components!...................................................................................................................!22!
IEC!socket!........................................................................................................................................!24!
Power/Main!Transformer!.......................................................................................................!25!
Audio!Output!Transformers!...................................................................................................!26!
PCBs!...................................................................................................................................................!27!
Speaker!and!Audio!Input!(phono)!Connectors!...............................................................!28!
Potentiometer!and!Potentiometer!PCB!.............................................................................!29!
Wiring!....................................................................................................................................................!30!
Power!Cables!.................................................................................................................................!33!
Safety!Earth!...............................................................................................................................!33!
IEC!to!Power!Switch!..............................................................................................................!34!
Power!Switch!To!Power!Transformer!...........................................................................!34!
Power!Transformer!to!Main!Power!Supply!PCB!.......................................................!35!
Main!Power!Supply!PCB!(B+)!to!Amplifier!Boards!(B+)!........................................!36!
Heater!Filament!Power!Cables!.........................................................................................!38!
Audio!cables!wiring!....................................................................................................................!40!
RCA!Terminals!to!Potentiometer!PCB!...........................................................................!41!
Potentiometer!PCB!to!Amplifier!PCB!.............................................................................!41!
Potentiometer!PCB!to!Amplifier!PCB!.............................................................................!43!
Amplifier!Boards!Wiring!.....................................................................................................!45!
Speaker!Output!Wiring!........................................................................................................!47!
Assembly!Completion!.....................................................................................................................!49!
Powering!Up!For!The!First!Time!...............................................................................................!50!
Questions!/!Support!........................................................................................................................!52!
Appendix!..............................................................................................................................................!53!
I.!Screws!/!Nuts!/!Bolts!Sizes!............................................................................................!53!
II.! Amplifier!PCB!Components!...........................................................................................!54!
III.! Main!Power!Supply!PCB!Components!.................................................................!54!
IV.! Heater!Filament!PCB!...................................................................................................!54!
V.! Schematics!............................................................................................................................!55!
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Figure!1!-!Filament!supply!board!with!the!four!diodes!......................................................!9!
Figure!2!-!Filament!supply!board!with!the!four!diodes!...................................................!10!
Figure!3!–!Main!power!supply!PCB!with!C4!capacitor!and!the!bleeder!resistor,!R5
!........................................................................................................................................................!11!
Figure!4!–!Main!power!supply!PCB!with!two!diodes!........................................................!12!
Figure!5!–!Main!power!supply!PCB!with!all!diodes!installed!........................................!13!
Figure!6!–!Main!power!supply!PCB!with!all!radial!capacitors!......................................!14!

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Figure!7!–!Main!power!supply!PCB!with!all!dropper!resistors!installed!.................!15!
Figure!8!-!Main!power!supply!PCB!fully!populated!...........................................................!16!
Figure!9!-!Main!power!supply!PCB!fully!populated!-!another!angle!..........................!17!
Figure!10!-!amplifier!PCB!showing!the!socket!side!...........................................................!18!
Figure!11.!Valve!socket!soldered!to!the!amplifier!board!................................................!19!
Figure!12!-!Amp!PCB!fully!populated!......................................................................................!20!
Figure!13!-!Amp!PCB!socket!side!with!a!valve!inserted!...................................................!21!
Figure!14!-!two!amplifier!PCB!completed!together!with!ECL82!valves!inserted!
(illustration!only)!...................................................................................................................!22!
Figure!15!-!Placement!of!all!components!on!the!mounting!bard!-!bottom!view!..!23!
Figure!16!-!the!complete!system!–!bottom!view!.................................................................!24!
Figure!17!-!Example!of!IEC!socket!installed!..........................................................................!24!
Figure!18!Mounting!the!main!transformer!...........................................................................!25!
Figure!19!-!Mounting!the!audio!transformers!.....................................................................!26!
Figure!20!-!example!of!PCB!being!mounted!on!the!standoff!.........................................!27!
Figure!21!-!speaker!and!audio!input!connectors,!and!star!earth!lug!.........................!28!
Figure!22!-!potentiometer!and!PCB!mounted!......................................................................!29!
Figure!23!-!Wiring!Diagram!-!USA!(120VAC)!.......................................................................!31!
Figure!24!-!Wiring!Diagram!-!UK!(240VAC)!..........................................................................!32!
Figure!25!-!Ground!safety!earth!from!IEC!socket!wired!to!the!chassis!and!secured!
by!shakeproof!washer!and!insert!lock!nut!..................................................................!33!
Figure!26!-!Live!(brown)!and!neutral!(blue)!cables!connecting!the!IEC!socket!to!
the!power!switch!....................................................................................................................!34!
Figure!27!-!Live!(brown)!and!neutral!(blue)!cables!from!the!power!switch!
supplying!main!power!to!the!power!transformer![0V,!240V]!............................!35!
Figure!28!-!Two!cables!(brown)!connecting!power!transformer!secondary!
terminals![0-250V]!to!the!main!power!supply!PCB![AC!IN].!!The!green!cable!
is!the!ground!level!cable!connecting!the![0V]!to!the!star!ground.!Note!the!red!
cable!carrying!B+!voltage!from!the![B+]!terminals!on!the!PCB!to!the!two!
amplifier!boards.!.....................................................................................................................!36!
Figure!29!-!Completed!main!power!supply!board!wiring!...............................................!37!
Figure!30!–!Twisted!cables!(red!and!black)!connecting!power!transformer!
secondary!terminals!(6.3V,!0V)!to!the!filament!power!supply!PCB!(AC!+/-!
IN)!..................................................................................................................................................!38!
Figure!31!–!Two!pairs!of!black!and!red!cables!(+V!and!0V)!feeding!the!two!
amplifier!boards.!The!green!cable!connecting!the![0V]!terminal!on!the!
filament!power!supply!PCB!and!the!star!ground!point.!The!polarity!of!the!H1!
and!H2!terminals!do!not!matter.!......................................................................................!39!
Figure!32!-!Heater!cables!coming!connected!to!the![H1]!and![H2]!terminals!on!
the!amplifier!boards.!.............................................................................................................!40!
Figure!33!-!Potentiometer!on!its!IO!PCB!................................................................................!42!
Figure!34!Connecting!the!RCA!input!connectors!to!the!potentiometer!IO!PCB!....!43!
Figure!36!-!Connecting!the!potentiometer!IO!PCB!to!the!amplifier!PCB.!In!this!
example!a!screen!cable!is!used.!Note!how!only!one!end!of!the!screen!is!
soldered!to!the![Audio!In!-]!terminal!.............................................................................!44!
Figure!37!-!Amplifier!Board!Wiring!..........................................................................................!47!
Figure!38!-!connecting!the!output!transformer!to!speaker!terminals!......................!48!
Figure!39!-!Complete!wiring!and!components!assembly!................................................!49!
Figure!40!-!Schematics!...................................................................................................................!55!

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Caledonian!Audio!
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Introduction
Congratulations! and! thank! you!for! purchasing! on! this! kit.! This! guide! enables!
readers!to!build!and!assemble!the!6BM8/ECL82!SE!Classique!MkII!DIY!amp!kit.!
The!6BM8/ECL82!SE!is!a!pure!Class!A!Single!Ended!valve!amplifier!that!uses!a!
two-stage!amplification!-!single!valve!per!channel!topology.!
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Its!features!include:!
• 2.5W!-!Pure!Class!A!per!channel!output!
• Single!ended!topology!
• Fast!Silicon!Carbide!Schottky!Diode!and!audio!grade!Electrolytic!Capacitor!
for!power!supply!producing!well!filtered!DC!power!
• DC!heater!filament!supply!
• Quality!electronic!components!
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If!you!have!any!questions,!please!get!in!touch!with!us!at:!
[email protected].!!
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We! also! value! any! feedback! that! you! might! have! after! going! through! this!
document.!
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• Heater!filament!PCB!Version!A!
• Main!power!supply!PCB!Version!A!
• Amp!PCB!6BM8!PCB!Rev!C!
• Alps!RK27!I.O.!PCB!Version!B!
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1. Only!parts!and! devices,! which! are! part! of! this! kit,!are! used!in! the! build.!
Caledonian!Audio!will!not!support!usage!of!any!other!parts!or!components!
other!than!supplied!and!mentioned!by!us!in!this!document!
2. The!supplied!aluminium!mounting!board!is!used!
3. Reader!is!capable!of!performing!wiring!/!soldering!and!understands!risks!
of!fatal!level!of!voltages!!
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• Screwdrivers!(multiple!sizes)!
• Long!nose!pliers!
• Soldering!iron!(with!solders!etc.)!
• Wire!cutters!
• Wire!strippers!
• Heat!shrinks!
• Cables!/!wires!for!hookups!and!power!lines!(please!see!wiring!diagram!for!
exact!ratings!and!colour!codes!
• Fuse!–!5x20mm!–!250VAC!–!1!Amp!slow!blow.!(This!is!to!be!added!to!the!
fuse!slot!in!the!IEC!socket)!
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Assembly Instructions
The!general!assembly!plan!is!as!follows:!!
1. Prepare!all!PCBs!(Power!supply,!heater!supply!and!2!x!amplifier!boards)!
2. Mount!power!transformer!onto!mounting!board!
3. Mount!audio!output!transformers!onto!mounting!board!
4. Mount!all!connectors!(power!and!audio)!
5. Mount!potentiometer!(and!its!I.O!PCB)!
6. Install!power!cables!
7. Install!audio!/!hookup!cables!
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PCBs Preparation
Heater Filament PCB
Place and solder the four diodes (D5, D6, D7 and D8); note the polarity of the
Diodes. See Figure!1. Use the marking on the PCB as a guide.
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Now place and solder the two reservoir capacitors C5 and C6. See Figure!2. Please
note the polarity of the two capacitors. The PCB is now complete.

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Main Power Supply PCB
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Begin!by!placing!and!soldering!capacitor!C4!and!resistor!R5.!See!Figure!3.!
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Now!place!and!solder!the!diodes![D1]!–![D4].!Please!note!the!polarity.!See!Figure!
4!and!Figure!5.!
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Now! place! and! solder! all!the! radial!electrolytic!capacitors.! Please! note! the!
polarities!on!the!capacitors.!See!Figure!6.!
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Place!and!solder!the!dropper/smoothing!resistors![R1]!–![R4].!Figure!7!shows!the!
resistors!placed!and!soldered.!The!main!power!supply!PCB!is!now!ready!(Figure!8!
and!Figure!9).!!

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Stuffing the Amplifier PCBs
There!are!two!amplifier!PCBs!included!in!the!kit,!one!for!each!channel.!Start!with!
one!of!them.!
Socket Soldering
On!the![Socket!Side]!of!the!amplifier!PCB,!place!and!solder!the!valve/tube!socket.!
See!Figure!10.!!
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Ensure! that! the! valve! socket!is! sitting! correctly! and! leveled! with! the!PCB.! It! is!
important!to!sit!the!socket!correctly!(the!axis!of!the!socket!and!PCB!are!parallel)!
as!this!will!determine!the!angle!of!the!valve!when!it!is!inserted.!!
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@<DL5V(Put!a!small!amount!solder!on!only!one!of!the!socket!feet!first!and!check!
and!make!sure!that!all!others!are!sat!correctly.!Only!proceed!with!soldering!others!
once!you!are!100%!sure!that!the!base!is!correctly!placed.!See!Figure!11.!
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Components Soldering
Now!turn!to!the!other!side!of!the!PCB.!
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Place!and! solder! all! the! resistors.! Follow! the!labeling! on! the! board!against! the!
labels!of!the!resistors’!packaging.!It!is!highly!recommended!that!you!double!check!
the!resistor!values!using!a!digital!multimeter.!!
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Now!place!and!solder!all!the!capacitors.!Observe!the!polarity!signs!for!C4!and!C6.!
See!Figure!12,!Figure!13!and!Figure!14.!
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