UralTone 18W guitar tube amp - DIY kit

In 1964 Marshall copied the Watkins Dominator circuit and launched the Marshall 1974 amplifier. 18W from EL84 pair, two channels, and a great tremolo. The 1x12" combo was loud enough for practicing and small gigs. The 1958 (2x10" combo) and 1973 (2x12" combo) models were also available.

The 18W has been one of the most popular DIY projects among tube amplifier enthusiasts. And for good reason. The circuit is simple and easy to make work well. The sound represents that well-known British amplifier tradition. Good dynamics, the distortion is beautiful and controlled. The volume level is just perfect. 

Circuit

The power amp of UralTone 18W is a traditional EL84 push-pull output stage that compresses particularly beautifully. When playing clean it offers lots of dynamics with that delightful high-end chime that only EL84 can produce. When driving harder, it gradually breaks into a richly distorted sound with lots of harmonic content. This kind of power amp is one of the best if you are looking for power amp distortion. 

Both channels have volume and tone pots. 

The tremolo channel has a rather rare tremolo circuit.

The original UK versions have an EZ81 rectifier, but as its availability is sometimes challenging today, we have replaced it with an octal base 5C4 / 5Y3 rectifier, which is still widely available and reasonably priced.

The amp is built in an aluminum chassis with the same external dimensions as JTM45. So easily accessible JTM45 head and combo cabs can also be used with our 18W.

Tubes

The power stage uses two EL84 tubes, which produce about 18-22W audio power in a push-pull circuit. The amp also accepts Russian NOS 6P14P (-EV) tubes. Fear-free DIYers can also try NOS 6P15P and 6P43P tubes, as well as American 5763 tubes (Note: they have a different pinout so rewiring is needed). 

The preamp and tremolo have three 12AX7 / ECC83 / 7025 tubes.

Lower gain 12AT7 or 5751 tubes can also be used. With a small change in the heater connection, cheaper NOS 6N2P tubes can be used, which still seem to be widely available in the world.

The rectifier is a NOS 5C4 tube, which roughly corresponds to the 5Y3 and GZ34 junction. It can be replace with 5Y3, 5AR4 / GZ34 or solid state rectifier.

The good thing about building kits is that if some of the tubes become expensive or availability deteriorates, there are often affordable replacements that work with little modification without any problems.

Components

The components in the UralTone 18W construction kit are top quality throughout the line. We don’t think it makes sense to save on parts prices even if the price of the kit goes up by ten or a hundred € because of this. The quality of the parts can be heard.

The chassis is made in Finland, transformers in Italy and Canada, sockets in Korea, capacitors are as far as possible Western production. The connectors, switches and small parts are same that we have used long time without any problems. We also sell these same parts to the highest-end boutique builders. 

Assembling

The UralTone 18W is relatively easy to assemble. The chassis has lots of space and the layout is clear and consistent.

It is essential to use a high-quality tin with 3-4% silver. For example, this model.

The soldering station must be at least of "reasonable quality" and the temperature suitable for lead-free tin (approx. 375C often works). We've put together some recommended tools in the enthusiast price range: TOOL KIT FOR BUILDING AUDIO EQUIPMENTS

It is important to note that Lead-Free solder will not work if the temperature cannot be raised high enough. So check your soldering tool max temperature. 

Enclosure

We ended up making an aluminum chassis with the same external dimensions as the JTM45 case. So you can use these cabs:

JTM45 / 18W combo and head

What is included in the package?

All necessary parts are included to assemble a working amplifier. The wooden case is sold separately or you can do it yourself.

How long does it take to assemble a building kit?

An experienced builder can build 18W in a day, a beginner needs 2-3 days.

Instrucions and support

Layout and BOM is supplied with the kit. Additional build guide can be found here:

https://en.uraltone.com/blog/18w-diy-kit-build-guide/

Unlimited email support is included! But we cannot give support over the phone or at our store (please respect this!). The best way to contact us is to reply to the order confirmation email.

Who is this DIY kit suitable for?

For anyone who appreciates good guitar sounds and enjoys doing things at hand. For those who want boutique quality with reasonable budget. Boutique amps prices include marketing (brand), profit of shops/supplier, assembly, etc. In DIY kits, many of these costs are left out.

What do I get if I buy your kit? 

A carefully assembled tube amp from our DIY kit corresponds to the quality of the most expensive boutique amps. The parts are top-notch, and the KIT is carefully designed. The price includes unlimited technical support via email. We do not leave the customer alone!