Caledonian Audio 6BM8/ECL82 SE 2.5W Classique MKII Assembly Manual
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Caledonian Audio 6BM8/ECL82 SE 2.5W Classique MKII Assembly Manual

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Assembly Manual
6BM8/ECL82 SE 2.5W Classique MKII
Version 3.0
Caledonian Audio

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Summary of Contents for Caledonian Audio 6BM8/ECL82 SE 2.5W Classique MKII

  • Page 1 Assembly Manual 6BM8/ECL82 SE 2.5W Classique MKII Version 3.0 Caledonian Audio...
  • Page 2 Version History Version Date Changes 0.1 of May 2018 Initial creation 1.0 of Nov 2018 Reviewed and accepted 2.0 of June 2019 Updated against a review 3.0 of October 2019 Now for 6BM8 PCB Version C for MKII...
  • Page 3 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual WARNING – DANGER OF SERIOUS INJURIES AND LOST OF LIFE The work conducted here deals with high-level voltages. It should only be conducted by qualified personals. Please be aware that capacitors can hold charges for a long time and they should be properly discharged prior to any work. 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 extreme care.

  • Page 4: Table Of Contents

    Table of contents Introduction ............................ 7 Assembly Instructions ........................ 8 PCBs Preparation .......................... 9 PCB ........................ 9 Heater Filament Main Power Supply PCB ...................... 1 1 Stuffing the Amplifier PCBs ..................... 1 8 Socket Soldering ........................ 1 8 Components Soldering ...................... 2 0 Mounting Components ........................ 2 2 IEC socket ............................ 2 4 Power/Main Transformer ....................... 2 5 Audio Output Transformers .................... 2 6 PCBs .
  • Page 5 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 7 – Main power supply PCB with all dropper resistors installed .... 1 5 Figure 8 - Main power supply PCB fully populated ............ 1 6 Figure 9 - Main power supply PCB fully populated - another angle ...... 1 7 Figure 10 - amplifier PCB showing the socket side ............ 1 8 Figure 11. Valve socket soldered to the amplifier board .......... 1 9 Figure 12 - Amp PCB fully populated .................. 2 0 Figure 13 - Amp PCB socket side with a valve inserted ........... 2 1 Figure 14 - two amplifier PCB completed together with ECL82 valves inserted (illustration only) ........................ 2 2 Figure 15 - Placement of all components on the mounting bard - bottom view .. 2 3 Figure 16 - the complete system – bottom view .............. 2 4 Figure 17 - Example of IEC socket installed ................ 2 4 Figure 18 Mounting the main transformer ................ 2 5 Figure 19 - Mounting the audio transformers .............. 2 6 Figure 20 - example of PCB being mounted on the standoff ......... 2 7...

  • Page 7: Introduction

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual 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. 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 If you have any questions, please get in touch with us at: support@caledonianaudio.co.uk. We also value any feedback that you might have after going through this document.

  • Page 8: Assembly Instructions

    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 Components and devices shown in this manual might be slightly different compared to ones included in the kit.

  • Page 9: Pcbs Preparation

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual 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. Figure 1 - Filament supply board with the four diodes Now place and solder the two reservoir capacitors C5 and C6. See Figure 2. Please note the polarity of the two capacitors.
  • Page 10 Figure 2 - Filament supply board with the four diodes...

  • Page 11: Main Power Supply Pcb

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Main Power Supply PCB Begin by placing and soldering capacitor C4 and resistor R5. See Figure 3. Figure 3 – Main power supply PCB with C4 capacitor and the bleeder resistor, R5...
  • Page 12 Now place and solder the diodes [D1] – [D4]. Please note the polarity. See Figure 4 and Figure 5. Figure 4 – Main power supply PCB with two diodes...
  • Page 13 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 5 – Main power supply PCB with all diodes installed...
  • Page 14 Now place and solder all the radial electrolytic capacitors. Please note the polarities on the capacitors. See Figure 6. Figure 6 – Main power supply PCB with all radial capacitors 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).
  • Page 15 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 7 – Main power supply PCB with all dropper resistors installed...
  • Page 16 Figure 8 - Main power supply PCB fully populated...
  • Page 17 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 9 - Main power supply PCB fully populated - another angle...

  • Page 18: Stuffing The Amplifier Pcbs

    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. Figure 10 - amplifier PCB showing the socket side 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.
  • Page 19 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 11. Valve socket soldered to the amplifier board HINTS: 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.

  • Page 20: Components Soldering

    Components Soldering Now turn to the other side of the PCB. 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. Now place and solder all the capacitors. Observe the polarity signs for C4 and C6. See Figure 12, Figure 13 and Figure 14. Figure 12 - Amp PCB fully populated...
  • Page 21 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 13 - Amp PCB socket side with a valve inserted Now repeat the process with the other amplifier board.

  • Page 22: Mounting Components

    Figure 14 - two amplifier PCB completed together with ECL82 valves inserted (illustration only) Mounting Components We should now have the following PCBs ready: 1. Main power supply PCB 2. Heater power supply PCB 3. 2 x amplifier PCBs We will now start mounting all other components onto the mounting plate in the following order: 1. IEC socket 2. Power transformer 3. Audio transformers (x2) 4. All PCBs (Main supply, heater supply, 2 x amplifier boards) 5. Speaker terminals 6. Audio input terminals 7. Potentiometer Refer to Figure 15 and Figure 16 for the exact placements for these components.
  • Page 23 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 15 - Placement of all components on the mounting bard - bottom view...

  • Page 24: Iec Socket

    Figure 16 - the complete system – bottom view IEC socket The orientation for the IEC socket matters as it determines the orientation of the IEC cable that will be inserted later. As a guide, install as seen in the example image below. It ensures that the fuse slot is below the IEC socket (when viewing it from the front). Figure 17 - Example of IEC socket installed...

  • Page 25: Power/Main Transformer

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Power/Main Transformer As a guide: 1. Remove all the nuts/washers from the four screws. Please note that the top cover of the transformer is also held by these four screws 2. Remove the four screws from the transformer and place the transformer carefully into the cut-out slot. Please make sure that the orientation is correct – the primary winding terminals (the 120/240 V) is closer to the outer edge of the board (don’t worry if you get it wrong – as long as you use and connect the correct terminals later) 3. Align the transformer so that all four holes are aligned with the four mounting holes on the mounting plate 4. One by one, insert the ceramic washer, washer, shake-proof washer onto the screw and then finish it off with the supplied nut. Please note the ceramic (red) washer in between the metal mounting plate and washer. See Figure 18. Figure 18 Mounting the main transformer...

  • Page 26: Audio Output Transformers

    Audio Output Transformers There are two audio output transformers; one for each channel. Place each of them so that the terminal pins are facing to the inside of the mounting board (the two output transformers will be mirror image of each other.) Mount them by using a the M4 screw, washer and locking nut (two sets per transformer). See Figure 19. Figure 19 - Mounting the audio transformers...

  • Page 27: Pcbs

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual PCBs There are 4 pieces of PCBs (main power supply, heater supply and 2 x amplifier boards) that we need to mount onto the mounting plate. Each PCB has four mounting holes which will be mounted on M3 standoffs and secured with M3 screws. 1. Referring to Figure 15 - Placement of all components on the mounting bard - bottom view and Figure 16, place all the standoffs (four for each board) on the mounting board and secure them with M3 screws from the opposite (front) side. Make sure the orientations of the boards are correct. 2. Place the correspondent PCBs on the standoffs and secure them with M3 screw. See Figure 20 as an example. Figure 20 - example of PCB being mounted on the standoff...

  • Page 28: Speaker And Audio Input (Phono) Connectors

    Speaker and Audio Input (phono) Connectors There are two pairs of speaker connectors and one pair of audio input (phono/BNC) connectors. Mount all the connectors onto the board. Make sure that no metal parts of the connectors are touching the metal plate. The plastic washers (part of the connectors) are there for this reason. Please refer to Figure 21 (ignore the star earth for now). Figure 21 - speaker and audio input connectors, and star earth lug...

  • Page 29: Potentiometer And Potentiometer Pcb

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Potentiometer and Potentiometer PCB A simple potentiometer I.O. PCB has been included to make the wiring easier. Please note the correct side to mount the potentiometer. Place it on the side which says, “Potentiometer this side” and solder all (six) terminals. Mount the potentiometer onto the mounting plate as per Figure 22 - potentiometer and PCB mounted. Figure 22 - potentiometer and PCB mounted You should now have all parts mounted on the mounting board ready to be wired together.

  • Page 30: Wiring

    Wiring Please make sure that you have all appropriate cables for this part. Refer to the wiring diagrams Figure 23 and Figure 24 (120 or 240 VAC systems) and the schematics first to get an idea what we are trying to achieve. Some notes: • Bear in mind that most of the connections / wires in the system are of high voltages (LETHAL). Please DO NOT TOUCH ANY BARE CABLES when the system is powered up EVEN if it is carrying low voltages • Charged up capacitors will be stay charged for long time. So please make sure that they have been discharged before touching them • It is advisable that you have all exposed terminals and high voltage cables insulated and use suitable wiring colour codes • Heater filament cables should be rated at 2 amps • Capacitor C1 is not mounted on the amplifier PCB We will start with wiring the power supplies and then move onto the audio signal circuitry.
  • Page 31 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 23 - Wiring Diagram - USA (120VAC)
  • Page 32 Figure 24 - Wiring Diagram - UK (240VAC)

  • Page 33: Power Cables

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Power Cables Safety Earth Start with connecting the ground safety earth connection from the IEC socket to the chassis (Figure 25). Please note that this connection should not be removed – ever. Figure 25 - Ground safety earth from IEC socket wired to the chassis and secured by shakeproof washer and insert lock nut...

  • Page 34: Iec To Power Switch

    IEC to Power Switch Connect the live (brown) and neutral (blue) from the IEC socket to the main power switch. See Figure 26. Figure 26 - Live (brown) and neutral (blue) cables connecting the IEC socket to the power switch Power Switch To Power Transformer Connect the main switch terminals (live and neutral) to the primary terminals of the main power transformer (0V and 240V for 240V system – refer to wiring diagram for 120V system). The two cables (brown and blue) will be carrying the main input AC voltages (240VAC) from the switch to the transformer. See Figure 27.

  • Page 35: Power Transformer To Main Power Supply Pcb

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 27 - Live (brown) and neutral (blue) cables from the power switch supplying main power to the power transformer [0V, 240V] Power Transformer to Main Power Supply PCB Connect the [0,250V] terminals from the [Sec 1: 100mA] on the power transformer to the [AC In] terminals on the main power supply PCB. These are the two brown cables seen in Figure 27 coming out from the transformer.

  • Page 36: Main Power Supply Pcb (B+) To Amplifier Boards

    Main Power Supply PCB (B+) to Amplifier Boards (B+) Now we need to connect the [B+] from the power supply PCB to [B+] on both of the amplifier PCBs (NOTE THIS IS THE HIGH VOLTAGE CONNECTION). This is the red cable from the power supply PCB seen in Figure 28. Connect the [0V OUT] on the power supply PCB to the star ground – this is the green cable seen in Figure 28. 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 [B+] terminals on the two amplifier boards.
  • Page 37 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 29 - Completed main power supply board wiring...

  • Page 38: Heater Filament Power Cables

    Heater Filament Power Cables Connect the 6.3V and 0V from the power transformer secondary [Sec2: 2A] to the [H1] and [H2] filament power supply PCB as shown in Figure 30. This is powering the heater filament supply board. The output from the filament power supply board is 6.3VDC which we will shortly connect to the heater filaments on the amplifier board. Figure 30 – Twisted cables (red and black) connecting power transformer secondary terminals [6.3V, 0V] to the filament power supply PCB [AC +/- IN] Now we will supply the heater filaments [H1] and [H2] on the amplifier boards with the 6.3VDC from the heater filament power supply board. The setup will be as follows: • Two pairs of cables will come out from the heater supply board (0V and +V) • Each pair goes to [H1] and [H2] terminals on the amplifier board • A ground level cable connects the [0V] terminal on the filament power supply board to the star earth connection. So, there will be 2 cables coming out from the [+V] and 3 from the (0V) terminals. Each cable will be carrying around 750 milliamps of current. Figure 31 and Figure 32 show the wiring between the heater power supply board and the heater filament terminals on the amplifier boards.
  • Page 39 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual 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 does not matter.

  • Page 40: Audio Cables Wiring

    Figure 32 - Heater cables coming connected to the [H1] and [H2] terminals on the amplifier boards. Audio cables wiring We will now perform the wiring of the audio signals, starting from the point where the signals enter the system. If you see the potentiometer IO PCB (Figure 33), you will notice that there are two groups of four terminals (labelled Chan1 and Chan2). The four terminals are: 1. [OUT +] 2. [OUT –] 3. [IN +] 4. [IN –] The idea is that we want to route the audio signals from the RCA connectors (where audio signals first enter the system) to the potentiometer and then to the amplifier PCBs.

  • Page 41: Rca Terminals To Potentiometer Pcb

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual RCA Terminals to Potentiometer PCB Referring to Figure 34 Connecting the RCA input connectors to the potentiometer IO PCB Potentiometer PCB to Amplifier PCB We will now connect the audio signal from the potentiometer PCB to both of the amplifier PCBs. Bearing in mind that we are working on CHAN1 side of the potentiometer (please refer to Figure 35): 1. Connect the [OUT+] on potentiometer PCB to the [Audio In +] on the amplifier board 2. Connect the [OUT-] on potentiometer PCB to the [Audio In –] (on the amplifier board) Do the same for CHAN2 side of the potentiometer board (but connect to the other amplifier board).
  • Page 42 2. Connect RCA negative (cold) terminal and the [IN-] terminal on the potentiometer PCB. Do this for both channels Figure 33 - Potentiometer on its IO PCB...

  • Page 43: Potentiometer Pcb To Amplifier Pcb

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Figure 34 Connecting the RCA input connectors to the potentiometer IO PCB Potentiometer PCB to Amplifier PCB We will now connect the audio signal from the potentiometer PCB to both of the amplifier PCBs. Bearing in mind that we are working on CHAN1 side of the potentiometer (please refer to Figure 35): 3. Connect the [OUT+] on potentiometer PCB to the [Audio In +] on the amplifier board 4. Connect the [OUT-] on potentiometer PCB to the [Audio In –] (on the amplifier board) Do the same for CHAN2 side of the potentiometer board (but connect to the other amplifier board).
  • Page 44 Figure 35 - 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...

  • Page 45: Amplifier Boards Wiring

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Amplifier Boards Wiring First of all, let’s have a look at the amplifier terminals on the amplifier board which we are working on. Table below describes all the terminals on this PCB. Item Label Function Connects To No. [H1], [H2] Heater filament [0V] and [+V] on power in. These the filament power are the DC voltage supply PCB input for the valve heater filament [Pentode Ground] Grounding the Star ground pentode section of the valve [O/T-] Return path from [Anode] on output the output transformer transformer [O/T+] Supplies the B+ [HT] on output (amongst others) transformer to the output transformer [B+] The high voltage [B+] on the main input for the...
  • Page 46 current flowing on the B+ cable (but worry not as the current is too low to have any negative impact). [H1] and [H2] These terminals should already by now, be connected to the filament power supply board. If not, please refer back to section: Heater Filament Power Cables. [Pentode Ground] Simply connect to the star ground. [O/T-] Connect to [Anode] terminal on the output transformer. [O/T+] Connect to [HT] terminal on the output transformer. [B+] Connect to [B+] terminal on the main power supply board (or [B+] terminal on the other amplifier board if daisy chaining method is used) [Triode Ground] Connect to the star ground.

  • Page 47: Speaker Output Wiring

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Connect to the [18] ohm terminal on the output transformer of the channel that we are working on. Wiring is now complete for one of the amplifier PCB. Repeat the process on the other amplifier PCB. Figure 36 - Amplifier Board Wiring Speaker Output Wiring The aim for this section is to connect the secondary winding of the output transformer to the speaker terminals. There are 4 speaker terminals for the two audio channels in the system. Each channel contains a positive (hot) and a negative (ground) cable. We will start with one of the channels. Please refer to Figure 37.
  • Page 48 Audio Signal Connection Connect the [8] ohm terminal on the [Secondary] winding of the output transformer to the positive (hot) speaker terminal. This is assuming that you will be using the 8 ohm speakers. Change this to another output impedance if necessary. Repeat the process for the other channel. The wiring for speaker output is now complete. Figure 37 - connecting the output transformer to speaker terminals...

  • Page 49: Assembly Completion

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Assembly Completion We have now completed the assembly of the kit. It should look something like Figure 38. Figure 38 - Complete wiring and components assembly...

  • Page 50: Powering Up For The First Time

    Powering Up For The First Time There are a number of items that you have to prepare/gather before powering up the amplifier for the first time. CAUTION– Valves can reach very high operating temperatures when in use and can cause burns if touched. Please see the checklist below: No. Item Note Done? IEC power cable For powering up the system Fuse For 220/230/240 (UK/Europe) version, a slow blow 1 amp fuse is needed. This is installed in the IEC socket. Speakers Never power up the amplifier without speakers connected. Bad things happen when this is done. Turn off the power as soon as possible and do not touch any of the...
  • Page 51 Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Normal power Once all above have been noted/done, you up and voltage can power up with the valves connected. readings Perform a complete voltage reading verification by comparing the voltages stated in the schematic diagram. Please allow margin of 10% on the reading, due to the fluctuations of the main AC supply and the electronic components.

  • Page 52: Questions / Support

    Questions / Support If you have any question, please get in touch with us at: support@caledonianaudio.co.uk...

  • Page 53: Appendix

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual Appendix I. Screws / Nuts / Bolts Sizes All fixings are included in the kit. Table below summarizes the sizes of the fixings used for all parts (use it as a reference). Part Fixings • Slot Pan Head Machine Screw Brass Output transformers Nickel Plated, M4, 20mm • RS PRO, M4, Bright Zinc Plated Steel Nylon Insert Lock Nut •...

  • Page 54: Amplifier Pcb Components

    II. Amplifier PCB Components Label Specification Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list Check packing list III. Main Power Supply PCB Components Label Specification Electrolytic Capacitor, 47 µF, 350 V, Radial Leaded, 16 mm C2, C3 Electrolytic Capacitor, Snap-in, 100 µF, 400 V Film Capacitor, 0.1 µF, 400 V, PET (Polyester) D1, D2, Silicon Carbide Schottky Diode, Z-Rec 600V Series, Single, 600 V, 2 D3, D4 A, 3.3 nC, TO-220 Through Hole Resistor, 100 kohm, 350 V, Metal Film, Axial Leaded, 500 mW R1, R2, Axial Wirewound Resistor 220Ω ±5% 7W R3, R4 IV.

  • Page 55: Schematics

    Caledonian Audio 6BM8-ECL82-SE-Classique Assembly Manual V. Schematics Figure 39 - Schematics...

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