Velleman K8010 User Manual

Total solder points: 600

MONO PURE CLASS A VALVE

Difficulty level:
beginner 1o 2o 3o 4o 5þ advanced

POWER AMPLIFIER

⇒ Pure CLASS A valve sound with high quality KT88 valves
⇒ High quality chrome plated enclosure
⇒ Chrome plated valve socket covers
⇒ Easy bias adjustment with LED indication
⇒ Removable bottom for easy access and service

K8010

⇒ High quality capacitors and components
⇒ Gold plated input and speaker terminals
⇒ Standby function
⇒ Soft start circuit for power transformer
⇒ Sensitivity adjustment for exact matching of two mono amps

Specifications

• Full class A 65Wrms in 4 or 8Ω

• Bandwidth: 4Hz to 90KHz (-3dB/1W)

• Harmonic distortion: 0.1% @ 1W/1KHz

• Signal to noise ratio: >110dB (A weighted)

• Input sensitivity: 1Vrms (adjustable)

• Power supply: 100, 120, 230 or 245VAC

• Power consumption: 230VA max.

• Dimensions: 355W x 360D x 157H

• Weight: 14Kg / 31lb

modifications reserved

MANUAL H8010P-ED1

5%

1

2

3

4

5

6

7

8

9

A

B

1%

COLOR= 2… 5

4K7= ( 4 - 7 - 2 - B )

4K7= ( 4 - 7 - 0 - 1 - 1 )

I P E SF S DK N D GB F NL

CODICE

C

COLORE

O
D
E

CODIGO

DE

CORES

CODIGO
DE COL-

ORES

VÄRI

KOODI

FÄRG

SCHEMA

FARVE

KODE

FARGE

KODE

FARB

KODE

COLOUR

CODE

CODIFI­CATION
DES
COU-

LEURS

KLEUR

KODE

0

Nero Preto Negro Musta Svart Sort Sort Schwarz Black Noir Zwart

Marrone Castanho Marrón Ruskea Brun Brun Brun Braun Brown Brun Bruin

Rosso Encarnado Rojo Punainen Röd Rød Rød Rot Red Rouge Rood

Aranciato Laranja Naranjado Oranssi Orange Orange Orange Orange Orange Orange Oranje

Giallo Amarelo Amarillo Keltainen Gul Gul Gul Gelb Yellow Jaune Geel

Verde Verde Verde Vihreä Grön Grøn Grønn Grün Green Vert Groen

C
O
D
E

0

1

2

3

4

5

Blu Azul Azul Sininen Blå Blå Blå Blau Blue Blue Blauw

Viola Violeta Morado Purppura Lila Violet Violet Violet Purple Violet Paars

Grigio Cinzento Gris Harmaa Grå Grå Grå Grau Grey Gris Grijs

Bianco Branco Blanco Valkoinen Vit Hvid Hvidt Weiss White Blanc Wit

Argento Prateado Plata Hopea Silver Sølv Sølv Silber Silver Argent Zilver

Oro Dourado Oro Kulta Guld Guld Guldl Gold Gold Or Goud

6

7

8

9

A

B

__________________________________________________________________________________________________________________________________________________________

TECHNICAL DATA*

• Output power: 65 Wrms class A / 85Wrms maximum

• Output impedance 4 or 8 Ohm

• Ultra linear output transformer

• Switch-on delay, to protect the output tubes: approx. 1 minute

• Standby circuit

• Built-in bias current indicator

• Switch-on delay for the supply transformer : 0.5s

• Power bandwidth: 8Hz - 45kHz (-3dB, ref. 50W)

• Frequency range: 4Hz - 90kHz (-3dB, ref. 1W)

• Harmonic distortion:

0.1% (1 kHz/1W)

0.7% (1 kHz/65W)

• Signal/noise ratio: > 110dB (A weighted wrt 85W)

• Input impedance: 100Kohm

• Input sensitivity min 1Vrms, adjustable.

• Damping factor (100Hz): > 12

• Power supply: 100, 120, 230, 245VAC

• Power consumption: 230Wmax. / 66W standby

• Dimensions: 355W x 360D x 157H

*Modifications and typographical errors reserved

3

_______________________________________________________________________________________________________________________________________________________

1. Assembly (Skipping this can lead to troubles ! )
Ok, so we have your attention. These hints will help you to make this project successful.
Read them carefully.

1.1 Make sure you have the right tools:

• A good quality soldering iron (25-40W) with a small tip.

• Wipe it often on a wet sponge or cloth, to keep it clean;

then apply solder to the tip, to give it a wet look. This is
called ‘thinning’ and will protect the tip, and enables you
to make good connections. When solder rolls off the tip, it needs cleaning.

• Thin raisin-core solder. Do not use any flux or grease.

• A diagonal cutter to trim excess wires. To avoid injury when cutting excess leads,

hold the lead so they cannot fly towards the eyes.

• Needle nose pliers, for bending leads, or to hold components in place.

• Small blade and phillips screwdrivers. A basic range is fine.

For this projects, a basic multi-meter is required

1.2 Assembly Hints :

þ Make sure the skill level matches your experience, to avoid disappointments.
þ Follow the instructions carefully. Read and understand the entire step before you perform each op-

eration.

þ Perform the assembly in the correct order as stated in this manual
þ Position all parts on the PCB (Printed Circuit Board) as shown on the drawings.
þ Values on the circuit diagram are subject to changes.
þ Values in this assembly guide are correct*
þ Use the check-boxes to mark your progress.
þ Please read the included information on safety and customer service

* Typographical inaccuracies excluded. Always look for possible last minute manual updates, indicated
as ‘NOTE’ on a separate leaflet.

1.3 Soldering Hints :

0.000

Mount the component against
the PCB surface and carefully
solder the leads

4

Make sure the solder joints are
cone-shaped and shiny

Trim excess leads as close as
possible to the solder joint

__________________________________________________________________________________________________________________________________________________________

ASSEMBLY OF THE MAIN PCB P8010:

Foreword:

For best results and easy handling of the large PCB (Printed Circuit Board), we will start by putting the
four large valve sockets in place. This will allow us to rest the board on the bench, without having the
component leads touching the bench surface.
When the component leads are put in the appropriate holes on the PCB, we recommend to gently bend
the leads outwards, so they stay on the board when it is flipped over to apply solder. You gain a reason­able amount of time if you put approx. 10 components in place every time, before you flip the board,
and make the solder joints.

5

_______________________________________________________________________________________________________________________________________________________

VALVE SOCKET

Also mount a 15 mm spacer on the following holes in

2718543

V...

Connect the valve socket terminals 1, 3, 4, 5, and 8 to the corresponding

1. VALVE SOCKET MOUNTING

Check the position of the notch in the centre of the valve socket, it must correspond to the position of the
notch in the circle printed on the PCB. Connect the leads to the corresponding isles on the PCB using a
small piece of supplied jumper wire.
IMPORTANT:
Make the connection exactly as shown in the illustration, otherwise the small piece of wire could touch
the bottom of the cabinet, see further.

the PCB (at the solder side); use a 6 mm M3 bolt:

q A spacer next to TRAFO1
q A spacer next to SK15
q A spacer next to SK6
q A spacer next to R62
q A spacer next to V6

20mm M3 BOLT

12mm SPACER

PCB

6mm M3 BOLT

15mm M3 SPACER

q V1
q V2
q V3
q V4

15mm M3 SPACER

5

4

6

7

5

4

3

3

8

1

2

8

1

points at the solder side of the PCB.
Use a piece of supplied jumperwire. Mount the wire in such way that it can­not touch the bottom of the cabinet. (see above illustration).

6

__________________________________________________________________________________________________________________________________________________________

D

C

B

A

DCB

A

D

C

B

A

DCB

A

2. JUMPERS

Note that for J1 to J4, two jumper wires have
to be mounted in the same hole, for extra cur­rent handling.

TIP

In order to get nice straight wiring, without too

much folding and measuring, follow these
hints:

• Put the jumper wire in place.

• Solder one end of the lead.

• Then carefully pull on the free end of the

q J1 (mount 2 wires in the same hole)
q J2 (mount 2 wires in the same hole)
q J3 (mount 2 wires in the same hole)
q J4 (mount 2 wires in the same hole)
q J5
q J6
q J7
q J8
q J9
q J10
q J11
q J12
q J13
q J14
q J15
q J16
q J17
q J18
q J19
q J20
q J21
q J22 indicated with ‘F1’

(mount 2 wires in the same hole)

3. JUMPERS FOR AC POWER SE­LECTION

For 100V input (mains), mount:

q JA at the voltage selection 1

q JA at the voltage selection 2

For 115V - 120V input, mount:

q JB at the voltage selection 1

q JB at the voltage selection 2

7

_______________________________________________________________________________________________________________________________________________________

DCB

A

DCB

A

DCB

A

For 220V - 230V input, mount:

q JC at the voltage selection 1

D

C

B

A

q JC at the voltage selection 2

For 240V -245V mains input, mount:

q JD at the voltage selection 1

q JD at the voltage selection 2

REMARK:
Strike out the NOT used mains voltage indica-

tion at the back of the enclosure !! Use a per-

manent black marker

4. DIODES (Check the polarity!)

D...

CATHODE

q D1: 1N4148
q D2 :1N4148
q D3: 1N4007
q D4: 1N4148
q D5: 1N4007
q D6: 1N4148
q D7: 1N4148
q D8: 1N4148
q D9: 1N4007
q D10: 1N4007
q D11: 1N4007
q D12: 1N4007
q D13: 1N4007
q D14: 1N4007
q D15: 1N4007
q D16: 1N4007
q D17: 1N4007
q D18: 1N4007
q D19: 1N4007
q D20: 1N4007
q D21: 1N4007
q D22: 1N4007
q D23: 1N4007
q D24: 1N4148
q D25: 1N4148
q D26: 1N4148
q D27: 1N5408 not on tape !
q D28: 1N5408 not on tape !
q D29: 1N5408 not on tape !
q D30: 1N5408 not on tape !

8

__________________________________________________________________________________________________________________________________________________________

5. ZENER DIODES
(Check the polarity!)

ZD...

CATHODE

q ZD1: 3V9
q ZD2: 3V9

6. ¼W & ½W RESISTORS

R...

q R1: 470 (4 - 7 - 1 - B)
q R2: 220K (2 - 2 - 4 - B)
q R3: 2K2 (2 - 2 - 2 - B)
q R4: 2K2 (2 - 2 - 2 - B)
q R5: 220K (2 - 2 - 4 - B)
q R6: 100K (1 - 0 - 4 - B)
q R7: 1K (1 - 0 - 2 - B)
q R8: 1K (1 - 0 - 2 - B)
q R9: 22K (2 - 2 - 3 - B)
q R10: 3.3 (3 - 3 - B - B - 9)
q R11: 3K9 (3 - 9 - 2 - B)
q R12: 1K5 (1 - 5 - 2 - B)
q R13: 1M (1 - 0 - 5 - B)
q R14: 1M (1 - 0 - 5 - B)
q R15: 1K (1 - 0 - 2 - B)
q R16: 47K (4 - 7 - 3 - B)
q R17: 470K (4 - 7 - 4 - B)
q R18: 680 (6 - 8 - 1 - B)
q R19: 3K9 (3 - 9 - 2 - B)
q R20: 10K (1 - 0 - 3 - B)

q R21: 10K (1 - 0 - 3 - B)
q R22: 1K5 (1 - 5 - 2 - B)

q R23: 1K2 (1 - 2 - 2 - B)
q R24: 560 (5 - 6 - 1 - B)
q R25: 100K (1 - 0 - 4 - B)
q R26: 220K (2 - 2 - 4 - B)
q R27: 100K (1 - 0 - 4 - B)
q R28: 220K (2 - 2 - 4 - B)
q R29: 10K (1 - 0 - 3 - B)
q R30: 2K7 (2 - 7 - 2 - B)
q R31: 1M5 (1 - 5 - 5 - B)
q R32: 1K5 (1 - 5 - 2 - B)
q R33: 3.3 (3 - 3 - B - B)
q R34: 8K2 (8 - 2 - 2 - B)
q R35: 220K (2 - 2 - 4 - B)
q R36: 10K (1 - 0 - 3 - B)
q R37: 100K (1 - 0 - 4 - B)
q R38: 220K (2 - 2 - 4 - B)
q R39: 100K (1 - 0 - 4 - B)
q R40: 220 (2 - 2 - 1 - B - 9)
q R41: 100K (1 - 0 - 4 - B - 9)
q R42: 47K (4 - 7 - 3 - B - 9)
q R43: 220 (2 - 2 - 1 - B - 9)
q R44: 220 (2 - 2 - 1 - B - 9)
q R45: 220 (2 - 2 - 1 - B - 9)
q R46: 2K2 (2 - 2 - 2 - B - 9)
q R47: 27K (2 - 7 - 3 - B - 9)
q R48: 220 (2 - 2 - 1 - B - 9)
q R49: 220 (2 - 2 - 1 - B - 9)
q R50: 100K (1 - 0 - 4 - B - 9)
q R51: 330K (3 - 3 - 4 - B - 9)
q R52: 330K (3 - 3 - 4 - B - 9)
q R53: 330K (3 - 3 - 4 - B - 9)
q R54: 330K (3 - 3 - 4 - B - 9)

9

_______________________________________________________________________________________________________________________________________________________

7. 1W RESISTORS

R...

2mm

q R55: 270 (2 - 7 - 1 - B)
q R56: 10K (1 - 0 - 3 - B)
q R57: 10K (1 - 0 - 3 - B)
q R58: 12K (1 - 2 - 3 - B)
q R59: 39K (3 - 9 - 3 - B)
q R60: 39K (3 - 9 - 3 - B)
q R61: 39K (3 - 9 - 3 - B)
q R62: 100K (1 - 0 - 4 - B)
q R63: 47K (4 - 7 - 3 - B)
q R64: 47K (4 - 7 - 3 - B)
q R65: 47 (4 - 7 - 0 - B)
q R66: 47 (4 - 7 - 0 - B)
q R67: 180 (1 - 8 - 1 - B)
q R68: 180 (1 - 8 - 1 - B)
q R69: 180 (1 - 8 - 1 - B)
q R70: 47 (4 - 7 - 0 - B)
q R71: 47 (4 - 7 - 0 - B)
q R72: 180 (1 - 8 - 1 - B)

8. LEDs (Check the polarity!)

COLOR = 2...5

LD...

CATHODE

q LD1: 5mm RED (2) BLINKING
q LD2: WILL BE MOUNTED

LATER, SEE SECTION 27

q LD3: 3mm YEL (4)
q LD4: 3mm YEL (4)
q LD5: 3mm YEL (4)
q LD6: 3mm YEL (4)
q LD7: 3mm GREEN (5)
q LD8: 3mm GREEN (5)
q LD9: 3mm RED (2)
q LD10: 3mm RED (2)
q LD11: 3mm RED (2)
q LD12: 3mm RED (2)
q LD13: 3mm RED (2) (next to R61)

9. IC SOCKETS
(Check the position of the notch!)

10

1

IC...

q IC1: 18P

__________________________________________________________________________________________________________________________________________________________

10. REED RELAYS
(Check the position of the notch!)

1

PIN 1

RY...

q RY1: VR05R121

11. DIP SWITCHES

SW...

12. RESISTOR TRIMMERS

Vertical type

RV...

q RV1: 100K
q RV2: 100K
q RV3: 100K
q RV4: 100K

Horizontal type

1

Check that switch 1 corresponds to pin 1.

q SW2: DS-4P

RV...

q RV5: 500K (470K)

11

_______________________________________________________________________________________________________________________________________________________

13. TRANSISTORS

q T1: BC516
q T2: BC547C
q T3: BC547C
q T4: BC547C

14. 5W RESISTORS

R...

T...

T...

T...

T...

15. PCB BLADE TERMINALS

Mount them as straight AS possible against the
PCB. A good solder joint is very important !

SK...

q SK1: 4 Ohm
q SK2: GND
q SK3: 8 Ohm
q SK4: BLUE
q SK5: RED
q SK6: YELLOW
q SK7: GRAY
q SK8: GRAY
q SK9: GREEN
q SK10: GREEN
q SK21: EARTH
q SK22: EARTH

2mm

REMARK: You will have one 15 Ohm 5W resis­tors left over for later use.

q R73: 15
q R74: 15
q R75: 15

16. CINCH / RCA CONNECTOR

Mount it as straight and square as possible
against the PCB.

q SK11: CINFP/90

12

__________________________________________________________________________________________________________________________________________________________

17. PCB TERMINAL BLOCK

some blocks slide into each other !

Mount these terminals with the wire inputs fac­ing the PCB edge:

q SK12: 2 POLE (large)
q SK13: 3 POLE

q SK14: 3 POLE
q SK15: 3 POLE

q SK16: 3 POLE
q SK17: 3 POLE

SK18 to SK20 are not mounted

18. VALVE SOCKET

19. SWITCH

SW...

IMPORTANT:

Don't leave a gap between

the SWITCH and the PCB!

SIDE VIEW

Mount it as square as possible against the PCB,
Also solder the metal support.

q SW1: 3P ON-ON-ON

20. CAPACITORS

6

V...

7

8

5

Mount them straight against the PCB

q V5: B9A
q V6: B9A

1

2

C...

3

4

9

Check the voltage rating!

q C1: 47nF (473, 0.047, 47000)
q C2: 100pF (101)
q C3: 330pF/400V (331)
q C4: 330pF/400V (331)
q C5: 68n/630V (683, 0.068)
q C6: 68n/630V (683, 0.068)
q C7: 68n/630V (683, 0.068)
q C8: 68n/630V (683, 0.068)
q C9: 68n/630V (683, 0.068)
q C10: 68n/630V (683, 0.068)
q C11: 680n/160V (684, 0.68)
q C12: 680n/160V (684, 0.68)
q C13: 680n/160V (684, 0.68)

13

_______________________________________________________________________________________________________________________________________________________

21. POWER RELAYS

The various relays have footprints that corre­spond to the footprints on the PCB:

q RY2: VR10V121C
q RY3: VR10V121C

RY...

q RY4: VR5V122C

RY...

22. ELECTROLYTIC CAPACITOR
(Check the polarity!)

C...

q C14: 4µ7
q C15: 100µF
q C16: 470µF
q C17: 470µF
q C18: 470µF
q C19: 470µF
q C20: 47µF/100V
q C21: 100µF/100V
q C22: 1000µF
q C23: 4700µF
q C24: 47µF/350V
q C25: 47µF/350V
q C26: 100µF
q C27: 1µF

14

__________________________________________________________________________________________________________________________________________________________

23. TRANSFORMER

TRAFO...

q TRAFO1: 12VAC

24. ELECTROLYTIC CAPACITOR
(Check the polarity!)

Generally these capacitors are of the snap-in
type and cannot be mounted incorrectly.

25. INSERT THE IC
(Check the position of the notch!)

1

PIN 1

IC...

q IC1: LM3914

q C28: 100u/400V
q C29: 220u/450V
q C30: 220u/450V
q C31: 220u/450V

C...

15

_______________________________________________________________________________________________________________________________________________________

LD...

5mm

5mm

26. 6.3V VALVE WIRING

q Wiring for the 4 valve sockets V1 to V4. Use the supplied brown wire. Twist them as shown in the

illustration. The polarity is not important. For safety, it is advisable to check with an ohmmeter
that the two 6.3V terminals are not shorted when the wiring is completed.

6.3VAC
f3

f4

f4

7

6

5

5

4

3

4

3

8

8
1

2

1

V4

f3

6.3VAC

f2

f2

f1 f1

3

2

1

8

3

1

8

7

V1

4

4

5

5

6

V3

7

6

5

5

4

4

3

3

8

8
1

2

1

VIEWED FROM SOLDERSIDE

27. SPECIAL LED (Check the polarity!)

q LD2: 3mm bicolor:

Carefully check the mounting of this LED:

3

1

2

1

3

LD2 ONLY !

2

V2

3

2

1

8

3

1
8

7

4

4

5

5

6

Check the complete assembly again for errors. Pay special attention to bad sol­der joints, shorts and wrongly inserted or misplaced components !

16

__________________________________________________________________________________________________________________________________________________________

ASSEMBLY INTO THE CABINET:

• Mount the caged nuts into the square holes as shown in the illustration. These nuts are later used to
fasten the covers.

CLICK INTO HOLE

FIG 1

• Mount the chromed feet on the four cabinet corners, with an M4 bolt. To avoid scratches on other
equipment, you can stick a piece of felt on every foot (not supplied).

• Mount a shakeproof washer and a 15mm threaded spacer on the front and back studding as shown
in the illustration.

15mm M3 SPACER

M3 LOCK WASHER

M3 BOLT

FIG 2

• Position the PCB in the cabinet, and fasten at the bottom with the supplied black button head hexa­gon socket screws (Use the supplied Allen key). At the component side of the PCB, two M3 bolts
fasten the PCB on the threaded spacers we mounted in the previous step.

• The mains inlet located at the back of the enclosure will be flush mounted as shown in the illustra­tion. Use two black button head hexagon socket screws , together with a shakeproof washer and an
M3 nut.

17

_______________________________________________________________________________________________________________________________________________________

M3 BOLT

MAINS INLET

M3 LOCK WASHER

M3 NUT

FIG 3

18

__________________________________________________________________________________________________________________________________________________________

• Make the connections as shown. Use the supplied blue wire for the neutral (N) terminal, and brown
wire for the live (L) terminal.

FIG 4

The earth terminal is hooked up with green/yellow striped wire. The female push-on connector on the

green/yellow striped wire must be soldered for best results.

SOLDER

FIG 5

Connect the earth wire to SK21 on the PCB. Remove the fuse holder lid, and insert a miniature glass

fuse. For mains voltages of 100-125VAC, use the supplied 8A slow-blow fuse, while for 220-240VAC
operation the 4A slow-blow fuse needs to be fitted. The spare fuse can also be stored in the fuse
holder lid.

• Mounting of the speaker terminals: Mount them as shown in the diagram. Watch the position of the
plastic insulator rings : one is flat, while the other has an elevated ring on the inside. There is no
need to mount the solder lugs.

SPEAKER TERMINAL

INSULATOR RING

NUT

NUT

INSULATOR RING

FIG 6

HINT : For easy fastening of the speaker terminals, immobilise the terminal by inserting a screwdriver in
the wire hole, while fastening the nuts.

IMPORTANT: The speaker terminals must be electrically isolated from the metal enclosure. For safety,
check for infinite resistance between every terminal and the metal enclosure.

19

_______________________________________________________________________________________________________________________________________________________

• Use the supplied 1,5mm² wire to make the connections. For best results, solder the female push-on
connector (fig 5). Apply enough heat, in order to make a good solder joint.

FIG 7

• Mounting of the toroid transformers : The output transformer marked ZD043 must be fitted according
to the illustration, on the right hand side of the cabinet. Watch the location of the wires.

RUBBER WASHER

OUTPUT TRANSFORMER

RUBBER WASHER

M8 BOLT

STEEL DISHED WASHER

FIG 8

!

IMPORTANT: Do not trim the wires of the transformers, leave them at their original length. If there
is more than one conductor in an insulating sleeve, you have to make sure they are soldered together
and make a good electrical connection before they are connected to the terminal block.

20

__________________________________________________________________________________________________________________________________________________________

• Connect the double yellow wire with the connector marked ‘YELLOW’ SK6.

Connect the red wire with the connector marked ‘RED’ SK5.
Connect the blue wire with the connector marked ‘BLUE’ SK4.
Use the supplied female push-on connectors (fig 5) and solder them onto the wires !
Connect the remaining wires to the terminal blocks SK16 and SK17. Pay attention to the colors.

FIG 9

• The supply transformer must be fitted according to the illustration, on the left hand side of the cabinet.

Watch the location of the wires. The sturdy grey and green wires, which supply the 6,3V filament
voltage, must sit on top.

RUBBER WASHER

POWER
TRANSFORMER

RUBBER WASHER

STEEL DISHED WASHER

M8 BOLT

FIG 10

21

_______________________________________________________________________________________________________________________________________________________

• Connect the grey wires to the connectors marked SK7 and SK8 (GRAY). Connect the green wires to

the connectors marked SK9 and SK10 (GREEN).
Connect the remaining leads to the terminal blocks SK13, SK14 and SK15

FIG

11

FINAL INSPECTION :

!

WARNING : THE PCB CARRIES VOLTAGES THAT EXCEED 400V !

THESE VOLTAGES CAN KILL ! MAKE SURE NO ONE CAN TOUCH ANY LIVE PARTS

Use suitable isolated measuring equipment

• Put the mains switch into its fully OFF position (all the way down).

• Connect the unit to a wall outlet, by means of the supplied cord. In some countries, the supplied plug

will not fit the local wall outlets. If this is the case, cut the supplied plug, and replace it with a suitable
one (not included). Make sure to wire it correctly : blue : neutral (N), brown : live (L), yellow/green :
earth.
If the mains voltage is present, LD2 should light continuously red.

• Turn the unit on by pushing the mains switch to its fully upward position.

LD2 should now blink for a while, this indicates the standby mode. After approximately one minute,
LD2 should light continuously green, indicating ‘ON’, and a relay should click.

• Now check the following voltages with a multimeter:

Measure about 6.3VAC between SK7-SK8 and SK9-SK10
Measure about 6.3VAC between pins 2 and 7 of the tube sockets V1 to V4 (illustration)

22

__________________________________________________________________________________________________________________________________________________________

FIG 12

!

SWITCH OFF THE UNIT AND REMOVE THE MAINS PLUG. WAIT A COUPLE OF MINUTES

UNTIL THE DANGEROUS HIGH VOLTAGE HAS DISSAPEARED

(UNTIL HIGH VOLTAGE INDICATOR LD13 TURNS OFF)

• Put the small valves in place:

V6 type ECC82 or 12AU7, CV491, 6189, 8136
V5 type ECC81 or 12AT7, CV455, 6201, 8162

• Reconnect the mains plug, and switch the unit ON again (switch in full upward position)

Wait until LD2 lights green continuously.

• Now check all indicated voltages on the PCB with respect to ground. A suitable ground for these

measurements is J4, at the centre of the PCB. The point indicated VB2 should carry approx.

3.5VDC.

REMARK : All voltages may vary a bit, due to mains voltage fluctuations. At this stage, you cannot
measure the 3.6VDC voltages yet.

CALIBRATION

Switch off the unit, disconnect the mains plug and wait until the high voltage has disappeared.
Turn the trim potentiometers RV1 to RV4 fully counter clockwise with a small screwdriver.
Put the four KT88 or equal tubes in their sockets. Watch the position of the notch.

IMPORTANT : The remaining 15 Ohm / 5W resistor must be hooked up between the centre and the 8 ohm
speaker terminal at the back of the unit. A valve amplifier must never be operated without a suitable load
at the speaker terminals. Make sure there is a good electrical connection between the terminals and the
resistor.

Bias current calibration
This calibration does not require a measuring instrument, as the bias level of each tube can be displayed
on the LED scale. The four dipswitches allow valve selection, while each valve has its own trim
potentiometer. RV1 controls V1, RV2 controls V2 etc…

IMPORTANT : This calibration determines the bias current trough the expensive output valves.
Therefore, it requires your absolute attention. Perform the calibration in the correct order.
No signal may be present at the input of the amplifier, during the calibration.

Flip all four DIP switches (SW2) to their OFF position
Every switch enables the bias readout of one valve, so do not switch on more than one at a time, or the
readout will be incorrect.

Reconnect the mains plug, and switch the unit ON again (switch in full upward position)
Wait until LD2 lights green continuously.

23

_______________________________________________________________________________________________________________________________________________________

Put the first switch in the ON position (use a pen or a small screwdriver)
Gently turn RV1 clockwise until the second or third LED lights (LD4 or LD5)
Switch off the first switch.
Switch on the second switch
Gently turn RV2 clockwise until the second or third LED lights (LD4 or LD5)

Perform the same operation with RV3 and RV4

Wait for about 10 minutes, before continuing the rest of the calibration.

Repeat the calibration of RV1 to RV4, but this time the trim potentiometers must be turned clockwise
until one or two green LEDs light.
When this operation is finished, check the 3.6V DC voltages at R65, R66, R70 and R71. Again, use J4
as ground reference.

FINALLY !

It is time to listen to your amplifier !
Switch off the unit completely before connecting or disconnecting any cables.
Connect a 4 or 8 ohm speaker to the correct terminals at the back of the unit. Speakers with imped­ances between 4 and 8 ohms can be connected to the 8 ohm terminal.
The common negative speaker terminal is located in between the 4 and 8 ohm positive terminals.

Hook up an audio source to the RCA connector at the back. Make sure the volume control of the source
is set to minimum before the unit is turned on.
The ‘SENSITIVITY’ trimmer located at the centre of the board allows you to trim the amplifiers input
sensitivity, so two units put out exactly the same level, which improves the stereo image. Normally, this
trimmer should be set fully clockwise.
If necessary, feed a mono signal to both amplifiers, and trim both sensitivity trimmers, until the sound
comes from the exact centre between both loudspeakers.

• Valve amplifiers run hot ! Operate them in a well ventilated area ! Do not put them in a closed

rack, stack or cabinet.

• It is a good habit to check the bias current on a regular basis, especially when the valves are

new.

• They need to run-in for a while, during which the bias level may shift.

• For short intervals between listening sessions, put the amplifier in stand-by mode (mains

switch in middle position).

FINISHING THE ENCLOSURE ASSEMBLY

• Check if none of the components on the PCB will touch the chromed cover plates, when they are put

in place.

• Turn the unit, so it rests on its left or right hand side.

• This allows you to fasten the bottom lid, by means of the supplied black button head hexagon socket

screws.

• Click the caged nuts into their holes on the chromed vertical plate (Be careful not to scratch the sur-

face).

• Mount the chromed cover plate on the chromed vertical plate with two silver button head hexagon

socket screws. Tighten by hand.

• Position this assembly onto the enclosure, and put the silver button head hexagon socket screws in

place. Tighten them by hand. Connect the chromed vertical plate to SK22 (chassis earth) with a

24

__________________________________________________________________________________________________________________________________________________________

length of yellow/green striped wire and 2 female push-on terminals. Make sure you solder both ter­minals. (See fig 5)

• Mount the top cover on the enclosure (Make sure the earth lead of the vertical plate is bent down, so

it does not get squeezed between the lid and the enclosure). Use the supplied black button head
hexagon socket screws.

• Mount the front panel. Use the supplied right angle mounting brackets, together with the shakeproof

washers and the M3 and M4 bolts. Take care of the correct position of the mains switch and LD2.

• Make sure everything fits well, and tighten all screws.

!

THIS AMPLIFIER RUNS HOT, OPERATE IT OUT OF THE REACH OF CHILDREN !

CHECK YOUR MAINS VOLTAGE

MAKE SURE IT MATCHES THE SELECTED VOLTAGE

REMOVE THE MAINS PLUG AND WAIT AT LEAST 15 MINUTES BEFORE REMOVING THE

COVERS

SOME PARTS MAY CARRY DANGEROUS VOLTAGES, EVEN WHEN THE UNIT IS UNPLUGGED

TROUBLESHOOTING

Hum coming from the speakers :

To make sure the amplifier is the source of hum, short the RCA input (by means of a spare male RCA
plug, which you short internally), and disconnect the earth connector SK21.
As a reference, listen at about 1m (3 ft) from the speaker, there should be an negligible amount of hum
present.
If there’s still a reasonable amount of hum present, check the bias current of every valve. Also check
the electrical connection between the PCB ground and the enclosure, which is done trough the bolt next
to R1.
A defective valve can also be a source of hum.
If hum is only present, when the amplifier is hooked up to an audio system, then a hum-loop could be
the cause. To verify if this is the case, disconnect SK21

Use good quality, as short as possible, interconnecting leads.
For best results, choose equal lengths for both left and right amplifier.

If the high tension is not present, check the transformer wiring and the mains fuse, located at the back of
the unit, below the mains inlet.

An intermitted crackling sound coming from the speakers could point to a defective resistor R62.
Replace it with the same value and power rating.

A continuous buzzing sound coming from the speakers or a crackling sound during bass peaks could be
caused by oscillation of the amplifier.
In this case, try raising the value or R46 (e.g. 2K7 or even 3K3). This will also slightly increase the input
sensitivity.
If your speaker system includes a piezo driver, make sure it has a 10 ohm/ 1W resistor in series with the
unit.

THE MODIFICATIONS MENTIONED ABOVE ARE ONLY TO BE PERFORMED WHEN REPEATED
INSPECTION OF THE CIRCUIT BOARD, SOLDER JOINTS AND WIRING DID NOT POINT TO ANY
OBVIOUS FAULTS OR MISTAKES OF ANY KIND.

25

_______________________________________________________________________________________________________________________________________________________

REMARK: Valves are very sensitive to mechanical shocks. Therefore, we recommend not to move the

unit when the valves are hot. Always let them cool down for a while. Avoid sudden temperature
changes, e.g. when the unit is moved from a cold room to a heated room. Always leave it idle for a
while, so it can adapt to the new environmental condition.
A valve that breaks down starts glowing cherry red. Turn off the unit immediately. Usually, the 47
ohm/1W cathode resistor of the defective valve will also need replacement.

If you have the impression that for some reason, the unit still does not operate as it should, you can
send it to our technical dept. for inspection. Send the PCB only, not the enclosure or the transformers.
Use the original box. Include a detailed description of the fault. Check www.velleman-kit.com for your
nearest Velleman dealer.

Velleman wishes you many hours of listening pleasure !

26

__________________________________________________________________________________________________________________________________________________________

DIAGRAMS

27

_______________________________________________________________________________________________________________________________________________________

PCB

C1

SK11

R1

C18

J9

100-120V/8A Slow
230-245V/4A Slow

AC POWER

N

L

SK12

12VDC

D17
D18

C2

R2

R3

D1

R4

T1

ZD1

R5

C14

SK21

C16

C15

YELLOW

RED

D11

D12

J2

80VDC

J5 J6

f4f3

C4

RED

SK15

C31

SENSITIVITY

R47

R16

C11

C12

C13

D5

D27
D28

R17

RV5

R18

SK22

A: 100VAC
B: 120VAC

D

C: 230VAC
D: 245VAC

C

245V
230V
120V
100V

0

T4

B

A

VOLTAGE

SELECTION1

R8
ZD2

R74 R75

RY4

D7

C19

C3

100VDC

12VAC

TRAFO1

2x J22

F1

J10

J11

D19

D20

A: 100VAC
B: 120VAC
C: 230VAC

J7

D: 245VAC

RY3

D8

C29

J12

R11

R62

220VDC

R12
75VDC

VIOLET

SK13

D C B A

VOLTAGE

C20

C21

SK7 SK8

f1

GRAY GRAY

R44

R63

R64

R13

C5

J19

BROWN

BLUE

ORANGE

SK14

FROM POWER TRANSFORMER

SELECTION2

R9

C30

f2

6.3VAC

J14J13

1 9

V5

D9

D10

BLACK

YELLOW

2x

R14
R45
R15
R46

R6

R7

RY1

1

T2

D2

D3

R55

C17

D4

T3

D6

RY2

SK1 SK2 SK3 SK4 SK5 SK6

YELLOWREDBLUE8 OhmGND4 Ohm

LD13

R61

SK16

SK17

FROM OUTPUT TRANSFORMER

R59

R60

ORANGE
BROWN
BLACK
BLACK
GREEN
VIOLET

J15

C6

300VDC

R56
R57

D29
D30

R73

SK9

f5 f6

R43

D14

D13

R10

J16 J17

R48

1

D15

J18

V6

6.3VAC

GREEN

D16

9

395VDC

GREEN

C23

J1

2x

SK10

f7 f8

155VDC

R49
R19

R50

C22

R40

J8

R58

190VDC

390VDC

C28

R41

R42

J3
2x

FROM OUTPUT TRANSFORMERTO LOUDSPEAKER TERMINALS

C24 C25

HIGH VOLTAGE INDICATOR

4

5

TO POWER ON SWITCH

6 3
5

2

4

1

SK18

1
2
3
4
5

D21

D22

6

SK19

R22

LD1

3 6

2

5

R23

1

4

SW1

1

LD2

3

D23

J20

D24

R24

TO POWER ON LED
SK20

1

2

3

-50VDC

V1

1

8

R21

C9

C10

2

1

3

R29

R26

R51

RV1 RV2 RV3 RV4

3

R28

SW2

R25

R27

1

R68

R69

4

5 8

R52

J21

YELL0W

YELL0W

K8010: 3.6VDC
K8011: 0.4VDC

V2

3

BIAS CURRENT ADJUST

LD6LD4LD3

LD5 LD9LD7 LD8

YELL0W

YELL0W

GREEN

VELLEMAN P8010'1 / P8011'1

1

LD11

LD10

RED

RED

GREEN

R65

K8010: 3.6VDC
K8011: 0.4VDC

R70

LD12

RED

RED

D25

J4

2x

R53
R54

R30
R31

D26

C27

C7 C8

R66

K8010: 3.6VDC
K8011: 0.4VDC

R71

R32
R33

C26

VB2

K8010: 3.6VDC
K8011: 0.4VDC

8

1

VB1

R34

IC1

V3

1

VB1 K8010: 1.6VDC
K8011: 0.2VDC

VB2 K8010: 3.5VDC
K8011: 0.45VDC

5

4

3

R20

1

DANGER
HIGH VOLTAGE

R36

R35

R37

R72

R38

R39

!

V4

58

4

3

PCB CONNECTED TO MAINS
HIGH VOLTAGE

R67

28

__________________________________________________________________________________________________________________________________________________________

DIAGRAM POWER SUPPLY SECTION

+V1

+V2

C30

TRAFO1

5
D

245V

1N4007

1N4007

9

4
C

D5

D22

D21

12VDC

1N4007

1N4007

ON

SW1

D17

D19

1N4007

230V

D3

1N4007

+V

STB

3

B

1N4007

R55

4u7

D23

D24

1N4007

115V

BC547C

270/1W

C14
C16

C15

1N4148

OFF

D18

1N4007

D20

2
A

7

SI

D2

1N4148D41N4148

T2

D6

1N4148

T1

BC516

3V9

ZD1

D1

1N4148

470u

R2

220K

100u

LD1

R24

L-56BHD

R23

C18

470u

R1

470

12VAC/2.5VA

1

0

100V

C17

R4

R5

R22

560

1K2

470u

2K2

220K

1K5

RY2

VR10V121C

T3

BC547C

R3

GREEN

LD2

RED

R61

R60

R59

2K2

D8

L-93WEGW

LD13

RED

39K/1W

39K/1W

390VDC

39K/1W

395VDC

1N5408

D27

R57

10K/1W

R56

10K/1W

POWER TRANSFORMER

RY3

VR10V121C

1N4148

BC547C

ZD2

1K

R8

D7

300VDC

D29

1N5408

3V9

1N4148

R58

R73

290

RED

T4

C19

470u

100u/400V

12K/1W

C29

220u/450V

C28

220u/450V

C27

220u/450V

15/5W

D30

1N5408

D28

1N5408

0

290V/0.7A

RED

VIOLET

245V

DBC

VR5V122C

RY4

ORANGE

R75

R74

+V

D9

YELLOW

230V

15/5W

15/5W

-50VDC

1N4007

D11

1N4007

V+

R9

BLUE

LD12

RED

4.75

10

3

C26

100u

D25

1N4148

-V

22K

D12

50V/0.1A

BROWN

120V

A

LD11

4.5

9

NC

C20

47u/100V

C21

100u/100V

D10

1N4007

YELLOW

RED

11

MODE

1N4007

100V

LD10

4.25

12

f4

GREEN

RED

SIG

SW2

1

R51

BLACK

LD9

4

13

5

BIAS1

6.3V/7A

0

LD8

RED

3.75

14

IC1

6

RHI

243

330K/0.5W

R52

f3

GREEN

GREEN

3.5

LM3914

R33

330K/0.5W

BIAS2

GRAY

LD7

f2

15

4.7

R53

GREEN

LD6

3.25

7

REF

BIAS3

RED

16

R32

330K/0.5W

R54

6.3V/7A

GRAY

LD5

3

1K5

BIAS4

f1

RED

2.75

17

8

ADJ

RLO

330K/0.5W

LD4

18

4

R30

RED

3K9

LD3

2.5

D26

R31

1
2

12K

RED

V-

R34

1N4148

10M

4A SLOW @ 230/245VAC

F1

L

8A SLOW @ 100/120VAC

MAINS

N

29

_______________________________________________________________________________________________________________________________________________________

DIAGRAM AMPLIFIER SECTION

-50VDC

-V

100K

100K

RV1

RV2

KT88

3

R69

180/1W

KT88

3

R68

180/1W

R26

R25

R27

300VDC

+V2

V2

V1

100K

220K

100K

1

1

4

4

68n/630V

220VDC

3K9

R11

R42

R41

3.6VDC

3.6VDC

R21

155VDC

47K/.5W

100K/.5W

190VDC

8 Ohm

BLUE

ZD043

TRANSFO3

ORANGE

BIAS2

8

5

BIAS1

8

5

10K

C9

47K/1W

R63

R62

100K/1W

C3

330p/400V

110VDC

C24

C6

68n/630V

R50

100K/.5W

C25

R70

7

2

R65

7

2

R28

68n/630V

1

6

ECC81

47u/350V

1

6

V6

47u/350V

4 Ohm

YELLOW

BROWN

47/1W

f2
f1

47/1W

f2
f1

R29

220K

C10

68n/630V

C5

2

7

V5

C11

680n/160V

R17

470K

ECC82

R7

BLACK

390VDC

R13

R14

2

7

IN

+V1

10K

68n/630V

1M

1M

C12

RV5

R6

C2

1K

BLACK

R36

10K

3

4

5

8

680n/160V

500K

3

8

100K

100p

C1

GND

INPUT

GREEN

f4
f3

f4
f3

C7

1K5

R12

9

C13

R16

R18

4

9

5

R19

47n

47/1W

R71

7

2

47/1W

R66

7

2

R35

220K

f1
f2

680n/160V

80VDC

47K

680

3K9

14
1

13
2

RY1

SI

GND

RED

VIOLET

BIAS4

8

V3

KT88

BIAS3

8

V4

KT88

C8

68n/630V

75VDC

R64

330p

R46

R15

27K/.5W

R47

C22

8
7

6

VR05R121A

GND

LS

5

5

R20

47K/1W

C4

2K2/.5W

1K

3.6VDC

3.6VDC

10K

-V

-V

R49

R10

3.3/.5W

1000u

R48

1

4

1

4

R38

220/.5W

C23

220/.5W

R72

R67

220K

100K

180/1W

180/1W

100K

f1

GRAY

4700u

f3

3

3

RV4

RV3

220/.5W

R44

D15

1N4007

D14

1N4007

R43

GREEN

R39

R37

6.3VAC

220/.5W

100K

100K

R45

D16

D13

R40

6.3VAC

f2

220/.5W

GRAY

1N4007

1N4007

220/.5W

f4

GREEN

30