BONAWATT × Toroidy.pl - Power Transformers

When designing audio equipment, it is easy to focus on components directly in the signal path: vacuum tubes, coupling capacitors, resistors, volume controls and output stages. Yet the quality and implementation of the power supply are equally important to the performance of the entire design. Tube amplifiers place particularly high demands on their power supplies. High anode voltages, heater circuits, control systems and highly sensitive amplification stages all coexist within one device. They must work together in close proximity without introducing unwanted interference into the audio path.

At BONAWATT, we therefore treat the power transformer as an integral part of the amplifier's architecture, rather than a separate component selected at the end of the design process.

Power supplies in tube amplifiers - a transformer designed for the device

The mains transformer must supply the correct voltages and currents to each section of the device. In tube designs, this can mean simultaneously powering anode circuits, tube heaters, auxiliary circuits, control systems, relays and digital electronics.

Each of these sections has different requirements.

Sensitive tube stages handle signals of relatively low amplitude, while nearby transformer windings may carry considerably more energy. This makes the transformer's construction, winding layout, shielding and suitability for the specific amplifier just as important as its basic electrical specifications.

When designing an amplifier, we therefore look beyond whether a transformer simply provides the right voltages. Its interaction with the rest of the power supply and the complete audio circuit also matters.

Since 2026, we have been developing a closer relationship with Polish manufacturer Toroidy.pl, which produces toroidal transformers for our new BONAWATT tube audio equipment.

A key benefit of this collaboration is the ability to commission transformers for specific design requirements. Instead of starting with a catalogue transformer and adapting the rest of the circuit around it, we can work in the opposite direction. We first define the device's requirements: the voltages and current demands of each section, grounding arrangements, rectifier and filtering architecture, and interference-control needs. A transformer tailored to the amplifier is then developed on that basis. This gives the designer much greater freedom. The transformer becomes a component designed alongside the device, rather than a constraint around which the rest of the power supply must be built.

Our new BONAWATT designs use Toroidy.pl transformers made for audio applications. The versions we use include an electrostatic shield between the windings, intended to reduce interference coupling from the mains side to the secondary windings. Of course, no single component can solve every interference problem in an audio device. The final result depends on the complete design: rectification and filtering, grounding, component placement, enclosure shielding and the signal path itself.

However, the transformer is one of the first components between the mains supply and the amplifier's electronics. It therefore makes sense to reduce potential sources of interference at this stage.

This is particularly important in tube equipment because of the high impedance of certain parts of the circuit and the sensitivity of input and voltage-amplification stages.

Technical specifications were not our only consideration when choosing a partner.

Developing new audio equipment involves many iterations. Voltages, current requirements and winding configurations can change between prototype revisions. The ability to obtain individual prototype transformers efficiently and then move to regular production batches makes the development process much easier. The manufacturer's proximity and Toroidy.pl's flexible approach help us move more quickly from a design to a physical prototype, and make any necessary adjustments before series production begins.

For a small high-end audio manufacturer, this makes a significant difference. It helps us retain control over the design while avoiding compromises caused by relying exclusively on standard, off-the-shelf components. Toroidy.pl also works with high-end manufacturers around the world, including LAMPIZATOR and Transrotor. We see this as a strong indication of quality and further confirmation of our choice of partner.