UralTone AC15 tube amp DIY kit

UralTone AC15 is our take on the sound palette of perhaps the most iconic British guitar amplifier family. The AC15 responds exceptionally well to the player’s dynamics. For traditional tones, nothing more than a guitar and amplifier is needed, but when required, the AC15 also works excellently as an extension of a pedalboard. The sound is healthy and well balanced.

Circuit

The UralTone AC15 power section is a traditional EL84 power amp that compresses especially beautifully, offering sparkling highs and gradually crumbling into harmonically rich overdrive when driven hard.

The power stage features a master cut control that can trim the high end just before the power stage.

The first channel is a late-1950s British circuit built around an EF86 tube with only a volume control. The channel is familiar from the first amplifier models in the series.

The second channel is the Top Boost channel with volume, treble, and bass controls.

The whole unit is built into an aluminum chassis matching the dimensions of a JTM45 / 18W, meaning readily available JTM45 head and combo cabinets can also be used with the AC15.

Tubes

The power stage uses two EL84 tubes producing over 15 W in a push-pull configuration. The power section also directly supports Russian NOS 6P14P series tubes. Mad scientists may also experiment with NOS 6P15P and 6P43P tubes, as well as American 5763 tubes with socket rewiring.

Channel 1 uses an EF86 tube, which fortunately is still available as NOS stock at a relatively reasonable price. If availability becomes difficult, the channel can either be modified for a 12AX7 or other pentodes can be used.

The Top Boost channel and phase inverter use 12AX7 tubes. You can also try lower gain 12AT7 or 5751 tubes. With a minor socket wiring modification, affordable NOS 6N2P tubes can also be used in the preamp, and these still seem plentiful worldwide.

The power supply rectifier is a NOS 5C4 tube, roughly equivalent to a hybrid of a 5Y3 and GZ34. It can be replaced with a 5Y3, 5AR4/GZ34, or a solid-state rectifier.

One of the benefits of DIY kits is that if tubes become expensive or harder to find, there are often reasonably priced substitutes that work flawlessly with minor modifications.

Features

• Traditional Class A British power section, approx. 15 W
• EF86 preamp for older VOX tones (our favorite!)
• Top Boost channel for classic AC30 tones
• 4-8-16 impedance selector switch
• Can be installed in 18W/JTM45 cabinets - same chassis size

Kit instructions

Instructions for building the kit can be found here:

UralTone AC15 illustrated building instructions

You can also download the layout image, parts list, and other required documents from the instruction page. In some cases, the schematic is delivered separately.

Browse through the instructions beforehand to see what the building process is like and what kind of guidance is available. The parts list shows the components included in the kit at the time of sale.

We do not include printed instructions with the package.

Links to related products

JTM45 / 18W combo and head cabinets
Speakers

Components

The components in the UralTone AC15 kit are top quality throughout. We see no sense in saving on component prices, even if it raises the kit price by tens or hundreds of euros. Quality can be seen and heard.

The cabinet is made in Finland, transformers in Italy, sockets in Korea, and capacitors are Western-made whenever possible. The connectors, switches, and small parts represent components we have found reliable through extensive long-term experience.

Assembly

The UralTone AC15 is relatively easy to assemble. There is plenty of room to work inside the chassis and the layout is clear and logical. It is important to follow the instructions!

In addition to the printed instructions, you can use our illustrated online guide:

https://uraltone.com/blog/uraltone-ac15-kuvia-rakentamisen-avuksi/

It is important to use high-quality solder with 3–4% silver content. For example, this model.

The soldering station should be at least reasonably high quality and suitable for lead-free solder temperatures (around 375 °C often works well). We have gathered recommended hobbyist-priced tools here:
Beginner’s soldering tool kit

It is important to note that old soldering irons intended for lead-free solder may not work if the temperature cannot be raised high enough.

Cabinet compatibility

For ease of cabinet installation, we chose to make the metal chassis with the same outer dimensions as a JTM45 / 18W cabinet. This allows the use of, for example, these cabinets:

JTM45 / 18W combo and head cabinets

What does the package include?

The package includes all the necessary parts to assemble a working amplifier. The wooden cabinet is sold separately or can be made yourself.

How long does assembly take?

An experienced builder can assemble the kit in a day, while a beginner may need 2–3 days.

Who is this kit suitable for?

Anyone who appreciates great guitar tones and enjoys working with their hands. Also for those who want boutique quality but whose budget does not stretch to high-end boutique gear. Boutique amplifiers include costs for design, marketing (branding), assembly (if made in Western countries), etc. Many of these costs are eliminated in DIY kits.

What value do you get for your money?

A carefully assembled amplifier from our kits matches the quality of the most expensive boutique devices. The parts are top-notch and the devices are carefully designed. The price also includes unlimited technical support via email or our support site. With us, the customer is never left alone!

What kind of tools do you need to build this kit?

Basic tools are enough, but especially beginners should invest in reasonable quality.

Especially the soldering station and solder must be good enough to ensure proper solder joints. Always buy your soldering station from a knowledgeable electronics retailer that can help you choose the right one for this kind of work.

We have assembled a tool kit for beginners that makes building easy and will take you far in the hobby. You can choose the tools you want from the package:

BEGINNER’S SOLDERING TOOL KIT

In addition to this, you basically only need screwdrivers. If you are unsure whether your current soldering station (perhaps inherited from your grandfather) is sufficient, feel free to contact us and we will help determine whether it is suitable to get started!

How can I get support if I have questions I cannot find answers to?

A properly built device according to the instructions will work. So always read the instructions carefully. In problem situations, read through this article and follow its instructions:

DIY tube amplifier troubleshooting

If something still concerns you, you can contact us via email. Unlimited technical support via email is always included in the price. Please note that we cannot provide support by phone or in-store, because our technical support staff do not work in the store or behind our phone numbers.

WARNING: Building guitar gear is highly addictive!

NOTE: Component deliveries in the kit may differ from the components shown in model images due to component availability.