Home>Support>Tech article
Guidelines and tips for assembling a tube guitar amp
Below, we address common issues regarding the assembly of a tube guitar amp. If you are not familiar with tube amp construction, please study these points carefully before beginning.

1. Safety

After you have assembled the kit components into the chassis, you may have to work inside the chassis where the electrical components are located. If you are not familiar with basic electronic safety practices, this could be dangerous. Please take time to learn and apply the proper precautions to keep yourself safe. There are numerous online videos and other sources that will help you learn basic amp safety procedures. Here are important tips for keeping safe during kit assembly and amp servicing.
(A) Unplug. Do not leave the amplifier plugged into a power outlet while you are working on it.
(B) Discharge. Even when the amp is unplugged, certain components most notably filter capacitors, store high voltages that are potentially dangerous. These capacitors must be discharged to be safe. There are two situations, and they differ in how the discharge procedure should be performed. A handy way to do this is to connect a shorting wire in series with a resistor (100+ ohms) between the plate of a preamp tube and the chassis (ground), using only one hand and being careful not to touch bare metal or wire with your hand. Alternatively, let the amplifier sit unplugged for more than several minutes to let the filter capacitors drain.
(C) Whichever procedure you use from (B), use a multimeter to be sure that no DC voltage remains in the capacitors.

2. Amp assembly summary

After you receive the amp kit and before you begin assembly, open the carton and remove all the parts carefully. Place the components on a well-lit clean surface. Check all of the parts according to parts list published at Ebay and verify that you have received everything.
2.1 Ready your tools and supplies
(A) 40 watt pencil-tip soldering Iron
(B)0.8-1mm diameter 60/40 rosin core solder (lead free is recommended)
(C) Wire stripper
(D) Wire cutter
(E) Multimeter with minimum 500 DCV.
(F) 18 AWG insulated solid wire rated 300V/12.5A
2.2 Assembly steps
If you are not familiar with tube amps, it would be a good idea to do some research before beginning the assembly process. There are many excellent online resources that deal with theory and construction tips. Then, examine the schematic, specifications and the construction files that are specific to the construction of this amp. Please clean and organize your work area before you start to assemble. The following procedure is the one we employ to assemble amps at our factory. The actual sequence can be altered to accommodate your personal habits.
(A) Clean the surfaces of earth and ground points on the chassis.
For safety, we use a single Main Ground (Earth) point, which employs one screw of the power transformer. For grounding points, we strongly recommend that you follow our layout (see P1.1, P1.2).
Clean chassis of amp
P1.1Clean surface of chassis (1)
Chassis of amp
P1.2Clean surface of chassis (2)
(B) Install the front and back panels, paying attention to align the plates with the proper holes in the chassis (see P2.1, P2.2).
Front faceplate cover chassis
P2.1 Front faceplate post on chassis
P2.2 Rear faceplate post on chassis
(C) Install the rubber rings on the chassis to protect the wires coming from the output transformer (see P3.1).
standy SW assembly on chassis
P3.1 Rubber rings on chassis

(D) Install the standoffs that support the hand-wired or PCB board on the chassis (see P4).


standby sw assembly
P4 Standby SW assembly
(E) Install the IEC power plug with fuse holder, Power switch (SW), standby switch (SW), and the input and output jacks. Note that the input and output jacks must be insulated away from the chassis (see P5, P6). The ground lugs are connected to earth ground by wires.
IEC power assembly
P5 IEC and output jack assembly
P6 Standby and input sockets
(F) Install the tube sockets on the chassis, and install the wires that run between the sockets (see P7.1-3).
Transformer of amp assembly
tube socket connection
tube sockets connection
P7 Tube sockets assembly and connection
(G) Install the power and output transformers. Each wires of transformers have clear label description. Please connect wires according to these label.Connect the yellow-green cable from the terminals of the IEC power plug and the power transformer to the appropriate screw of the power transformer. Twist the nut tight to make sure there is a good ground (see P8).
Power and output transformer assembly
Power and output transformer assembly
Transformers assembly on chassis of amp
P8 Transformers assembly on chassis
(H) Connect the power and standby switches (see P9)
Ground,Power SW
Powertransformer connection P/T SW
Power SW, P/T SW
Ground of amp
AC Ground , power SW
Standby SW connection

P9 AC ground , Power SW and Standby SW assembly

(I) Assemble the eyelet main board and potentiometers board. Each potentiometers has a tab that serves to stop the potentiometers from rotating in the chassis. Be sure to align the tab with the small holes on the chassis. Install all parts only finger tight until all parts are in place, and then tighten (see P10).
Hand wired board assembly on chassis
P10 Assembly of hand wired board
(J) Connect the ouput leads and filament wires. Twist the output leads from the transformer to the output tubes. Keep the wires short at best to eliminate amplifier squealing to eliminate amplifier squealing. Twist the two filament wires of each tube. This will help minimize hum. (See P11,P12).
Connection of output jacks of amp
P11 The sockets on rear plate connection
Output jack connection
Output jacks connection
P12 Output Jack connection
(L) Control board connection(P13)
Control board connection
P13 Control board connection
Master and presence controller connection
P13.1 Master and Presence controls connection
Wires the input jacks with shielded cables.Use shielded wire from the input jacks to the tube and be careful when wiring input jacks.The ground wires on the input jacks go to the pre-amp ground along with the board ground at that end. To prepare the shield wire (co-axial cable) for connections:
1. Cut back the outside plastic covering at both terminals by about 5/8" to reveal the braided shield.
2. At the one terminal , pull back the shield and cut it off at the 5/8" mark. Put some heat shrink around the terminal covering the area where it was cut off.
3. At the other terminal, pull back the shield but poke a very fine screw driver or pick into the shield and work out a 'hole'. Fish the inside conductor through this hole and pull it through.
4. Twist the braid together.
5. Finally, cut back the outside plastic covering on the inside conductor at both ends by about 1/4" (M) Check each individual component one by one before power up. Measure the resistance from each part that has a ground connection to the chassis. All should be less than 1 ohm, typically 0.5 ohms. Measure the resistance from the AC input to ground , It should be infinite.
Shield wire cut
P14 Shield wire cut and solder
2.3 Power Up
Note: Smell smoke when amp turn on. Turn it off immediately and re-check the connections.
Test the High voltage AC and ensure that voltage range is in the correct. Test the filament voltages and ensure they are on the correct pins for all tubes. Power up without tubes installed. Turn on the StandBy switch.Check the plate voltages of tubes. Compare these values with voltages in Voltage layout map. The plate voltages of empty load will be same or slightly higher than the load voltages listed on the Voltage layout map. Install all tubes, connect speaker, not plug guitar into amp then turn volume to minimum, power up. Pay attention to abnormal sounds of amp such as loud transformer vibrations or humming , other crackling sounds. Check if any of the components besides the tubes are getting hot - check the power resistors. Carefully check voltages on all the tubes. Turn the volume up a bit. Touch the input lead with a small screwdriver to see if it can induce some hum, or static sound. Insert one 6.35 inch plug into input jack, touch one end.Should get a louder hum, this is means amp good. Plug in guitar and take the amp for a test run. (NEXT)
2009 Kldguitar Electronics. All rights reserved. Terms/Privacy