How to build UralTone Champ 5F1 V2.0 KIT

The Champ 5F1 is one of the most legendary guitar amps of all time. And for a good reason: the simple structure and signal path allows great dynamics and bring out all the playing nuances.

Version 2.0 of the UralTone Champ kit has been taken to a whole new level.

Assembling a kit is possible even for a beginner, as long as care is taken and all the instructions are studied well before starting.

  1. UralTone 5F1 tweed champ 2.0 kit
    €270.00 €217.74
    Champ 5F1 is one of the most legendary amps ever designed. And for good reason: it sounds great, deliveres all the players nuances and is really easy and cheap to make. Very good DIY project. Learn More

Links / Downloads:

UralTone Tweed Champ 2.0 osalista - BOM

Step 1 - Prepare

If you are an inexperienced builder you have to first learn the secrets of good soldering and the basics of safe working.

The most important thing is your safety!

We will not go through these points here in detail, but follow this guideline throughout the project:

If you don’t know what you’re doing, or you’re unsure, don’t do it!

Rather re-read instructions, google for more information, or ask us for advice.

Step 2 - Check all the parts

Check that all parts according to the parts list have been delivered and sort them by component type (resistors, capacitors, connectors, tube sockets, etc.).

If anything is missing, please contact us and we will correct our error.

Step 3 - Quiet and peaceful workplace

Reserve table space for the project that you will not need for anything else during the entire project. It takes about 1 working day for a professional to build, 2-3 times more for beginners.

Take coffee or tea next to you, relax and focus your thoughts on this project alone.

Step 4 - Lets build a tube amp

Intermediate Note: If you already have the amplifier cabinet ready, drill chassis mounting holes at this point. After mounting the transformers, it is more difficult to align the locations of the mounting holes.

The first step in stacking is to attach the mechanical parts (hardware) and transformers to the chassis. Attach the tube sockets, transformers, potentiometers, connectors, switches, etc. according to the layout diagram.

Mechanical Installation

Typical errors:

  • The tube sockets are connected to the wrong side of the chassis (check the pictures for proper attachment)
  • Tube sockets are mounted in the wrong direction. Check that the guide track of the octal bases (large bases) points in the same direction as shown. Don't worry about the tube socket pin numbers. Check the noval tube sockets (pre amp tube sockets): spacing between pins 1 and 9 should point in the same direction as in the pictures.

Please note:

  • Cut the potentiometers locking pins with pliers (easily breaks when folded), those are not needed here.
  • Note that the washers are on the correct side of the chassis. Star washers will be installed inside the housing, smooth washers should be installed between the chassis and the nut. Be careful not to scratch the faceplate while attaching parts.
  • Make sure there is enough distance between the AC adapter and power switch contacts. If necessary, turn the power switch over.

Step 5 - First solderings

The kit uses a fabric-insulated push-back cord that does not need to be stripped with pliers. The fabric insulation of the cable is pushed inwards from the end of the cable to expose the conductor.

Connect and solder the wires that do not connect to the eyelet board at any point. These are easier to solder before installing the eyelet board. The wires that go to the eyelet board will be soldered later.

So at this point, solder: -the mains transformer cables for the lamp and the rectifier tube base -the mains cable for the mains switch and fuse -tube heater cables -the cables of the terminal and the output transformer insofar as they do not go to the eyelet board. Any unused mains transformer cables must be cut and insulated with a shrinking tube to prevent short circuits.

Also use a shrinking tube to insulate the wires coming to the power switch.

The protective earth wire must be left longer as shown so that it will be the last to be detached if the mains cable fails. This is the most important connection of the amplifier, screw it absolutely tight so that there is a lock washer between chassis, nut and connector.

Attention:

  • Also check the mains transformer wirings from the transformer package and / or from the manufacturer's website. Make sure that the color codes in the layout correspond to the correct voltages (indicated in the layout image). Sometimes manufacturers change color codes without notice, and we don't always notice updating the layout image in a timely manner.

Step 6 - Populate eyelet board

Load the components on a eyelet board. Please note the following:

  • The electrolytic capacitors should be installed in the correct direction. The plus terminal is marked with a groove and a minus with a line. Make sure that each electrolytic capacitor is facing the right way! An incorrectly connected capacitor can explode (!).
  • Populate all components so that the values ​​on the side are visible. Always connect different parts, eg resistors, in the same direction. This makes it easier to read the values ​​and looks more professional.
  • Bend the legs of the components through the eyelet so that any connecting wire that may enter the same hole can still fit through the hole.

After loading all the parts on the eyelet board, check all the parts one by one and compare with the layout. Make sure all parts are in the right places and in the right direction!

Step 7 - Soldering eyelet board

Start soldering the eyelet board from one end of the disc and proceed systematically to the other end. Always solder all components and parts from the eyelet pin at once. Cut off the long legs of the components before soldering. If the legs or copper strands of the cables are left sticking to the surface of the solder, cut them clean without damaging the solder.

The soldering of the component board can be made either from above or below. A cleaner result is obtained by tapping from below, which makes it easier to clean the flux residues.

Wire the cables as shown. The wire lengths are marked in the layout diagram.

Step 8 - Attach the eyelet board to the chassis

When the eyelet board is ready, it is time to attach it to the chassis. Make sure that the screws on the eylet board do not hit the legs with the components and cause a short circuit.

Start soldering the wires from the eyelet board at the other end of the board (input side). At the same time, connect the input connector resistors and other components outside the board. When turning the connectors, make sure that you plug the correct wire into the correct lug. Turn the jacket in the same direction as in the layout image.

Step 9 - Double check!

Once all the parts have been populated, solder in, and screwed in place, you have to go through everything again. Check each connection, solder, component installation direction, and wiring step by step. It is best to go through each eyelet pin and follow the components and wires coming out of it comparing them to the layout image. At the same time, mark which components, wires and eyelet pins have been checked. This step must take at least an hour!
Almost all operating problems are due to human factor. The most common fault is a forgotten or poorly made solder or joint. The second most common fault is the wrong component in the wrong place. The third most common fault is a short circuit between two points (for example, an excessively long component leg hits the housing under the eyelet board). When everything is guaranteed to be correct, it's time to turn on the machine!

Step 10 - Powering the Champ

When you are 100% sure that everything is correct, it is time to turn on the power. We assume here that the only test device you have is a multimeter.

Make sure the device is on a table that is clean. Excess parts, wires, etc. must be cleaned off the test table to prevent them from being accidentally short-circuited. For example, fragments of tin wire that are difficult for the eye to see can be devastating if they are trapped inside the amplifier. Shake the amplifier in the air with the component side down and make sure that no extra loose material is left inside the case.

Using a multimeters ohmmeter, measure the resistance of the ground points relative to the chassis. Turn the multimeter for the resistance measurement (smallest area), connect the black test lead in the chassis and go through all the ground points of the layout image one by one. The meter should show zero or near zero (maximum a few ohms). If not, check the connections of the problem point once more.

Make sure the fuse is installed in the fuse holder.

Turn the power switch to the "on" position. Make sure the tubes are not in the sockets. Connect the appliance to a grounded mains socket. If you notice any suspicious sound, smell or smoke, etc., pull the plug immediately from the wall. If there are no problems, you can make the first voltage measurements.

Place the multimeter in the AC voltage measuring range. Select the highest voltage range (400VAC minimum). Attach the black test lead to the housing, eg with a alligator clip or use holes in the housing. Measure using one hand, the other hand is in the back pocket during the measurements. This prevents electric shock in panic situations, where current flows from hand to hand through the heart. Measure measuring points starting with AC, eg AC 340V. At this point, if the the meter should display 340V with a tolerance of about 15% (i.e. 340V + -15% / 290 - 390V is ok at this point). Unplug the power cord between all measurements.
The voltage of the filaments is measured at the base of the pilot lamp. There should be about 6.3VAC between the soldering pins of the base (without tubes about 7VAC is still ok).

Once everything is found to be correct, it is time to put the rectifier tube in position. Make sure the tube goes in the correct direction. In many modern tubes, the base will break easily if the tube is attempted to be installed in an oblique or incorrect position to the socket. The guide slot tells you how the tube should be installed in its position.

Turn on the power again. And once again, if you notice anything suspicious, unplug the power cord immediately. Measure the voltage at point A. At this point, the measurement tolerance is 20%, because the measured values ​​in the layout image have been measured with all tubes installed.

If all is well, you can install the remaining tubes in their sockets. Note that there might be some energy stored inside the capacitors of the power supply. So you can get an electric shock even if the device is not connected to the mains. Connect the speaker cable to the speaker jack. You can also use an dummy load if you own one. Adjust all pots to zero. Connect mains cord to the mains socket. Wait a moment, and if you do not hear loud noises from the speaker, measure all the voltages at the DC measuring points. Again, other hand in the back pocket and the black probe in the chassis. Use the highest DC voltage range of the multimeter (minimum 500VDC). The tolerance is about 15%, ie the measurement results do not have to be identical to the layout image. Voltages may vary a little bit because of mains voltage variations and the tolerances of the components.

11. Biasing the Champ

The Champ power tube is cathode biased, that means the plate current (bias) is set with cathode resistors so no adjustment needed.

12. Plug in the guitar and open your ears

When all is measured to be correct, you can plug the guitar into the input jack, open the volume and tone controls, and enjoy the sound of your brand new tube amp BUILD BY YOURSELF! This probably the most rewarding moment of the day.

If something does not work, sounds strange, or suspicious, turn off the power and continue to investigate and troubleshoot any issues that may be related to the problem. This is normal, do not panic, you will find the problem! Everyone makes mistakes and, luckily, everyone is able to correct their mistakes.

13. Support

We are happy to provide technical support! To get the best support, please email us and mention the following in the first message:

  1. Which DIY KIY you are building
  2. Your name and order number (if available)
  3. Please describe the issue as accurately as possible.

    We get a lot of messages, so we don’t always remember if the matter has been discussed before. That is, always say it all over again.
    Never delete old messages from a thread
    We aim to respond within 24 hours on weekdays, but sometimes support is overloaded. If you do not receive a response within two days, please contact us again.

Congratulations, you have in your hands a very high-quality tube amplifier that will give pleasure to guitar players and listeners for decades, as long as you remember to change the tubes regularly. Generally, the power tubes last 2-5 years depending on the hours of use and the preamplifiers a little longer. If the device starts to show symptoms after a year(s), it is always advisable to replace the tubes before any other maintenance.

Mikko Kankaanpää / Helsinki / Finland 2021