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Triad Magnetics: Serving the Audio Industry With Small Products That Pack Big Sound

What Is An Audio Transformer?

Audio transformers are electronic devices that transmit frequencies within the audio band. They are used in audio amplifier circuits to:

  • Increase or decrease signal voltage
  • Increase or decrease circuit impedance
  • Convert a circuit from balanced to unbalanced (or vice versa)
  • Allow AC current to flow through and block DC current
  • Isolate one device from another


Applications of audio transformers include use with microphones during the input stage, loudspeakers during the output stage, and amplifiers for interstage coupling and impedance matching. Regardless of their stage of employment, when using an audio transformer, there are several factors—such as power capacities, primary and secondary impedances, and frequency response—to keep in mind to ensure optimal performance.

As a leading provider of specialized magnetics products, Triad Magnetics understands all of these nuances. Our broad experience in the custom magnetics product market affords us insight into proper design, building, and selection practices for audio transformers, allowing us to pass along our expertise to our customers.

Triad Magnetics’ Legacy in the Audio Industry

At Triad Magnetics, we have deep connections to the audio and sound processing industry. We’ve made several significant contributions to the industry, including legacy products that have long been a staple in audio and sound studios including the recently re-released legendary J Series of audio transformers.  Our reputation for innovation goes back to our company’s beginning. Not long after we were founded in the 1950s, we helped to revolutionize amplifier technology. Our team, working with Leo Fender, created the world’s first 100W output transformer, pushing past the limits of what magnetics had previously achieved. From there, we left behind a trail of audio industry accomplishments in our wake, including:

  • Partnering with Fender (a guitar manufacturer) and Dick Dale (the surf-rock pioneer) to turn our 100W output transformers into the world’s first 100W guitar amplifier
  • Designing transformers for the professional broadcast and recording industry.
  • Establishing the company as a leading audio transformer supplier for television manufacturing during the television boom
  • Developing and providing products for low power audio and telemetry in unmanned space flights and, later, the Apollo mission

The latter point is one we are particularly proud of, as—without Triad—NASA may never have reached the moon. Jim Tracy, a sales manager who has been with us for 60 years, once said, “The SP series was definitely ahead of its time. The design was so innovative it’s still being used in aerospace products today. The high grade, reliable audio in such a small space still stands the test of time.”

At Triad Magnetics, we take pride in our long and close history with the audio industry. While our past contributions have helped the industry advance to where it stands today, we hope to continue to grow it even further.

Audio Transformers From Triad Magnetics

Among our standard product offerings, we manufacture 41 unique, high-quality audio transformers. Each of these transformers is available off the shelf for immediate delivery. Our designs can be categorized into three varieties:

Red Spec Printed Circuit Audio Transformers

These highly reliable transformers offer precision and durability. They are manufactured with epoxy molded cases and gold plated leads. With an operational range of 300 Hz to 100 kHz, they are ideal for a broad selection of applications.

Plug-In PC Audio Transformers

These transformers are designed for use in printed circuit (PC) designs. Their high versatility makes them suitable for use in a wide range of applications, including input, isolation, line matching, telephone coupling, pulse trigger, and interstage coupling.

J Series Professional Audio Transformers

Triad meticulously followed the original design and construction details including paper section windings, high-nickel laminations and specially tooled mu-metal shield can for this recently released series of audio transformers. Originally released in 1950 Triad’s J Series transformers permitted amplifiers to exceed broadcast standards closely approximating the performance characteristics of more costly hermetically sealed units.

Data/Voice Coupling Transformers

These telecommunication transformers are designed for devices that use the dial-up switched telephone network. They are found in applications that involve isolation, repeat coil, impedance matching, bridging, hybrid circuits, and line balancing.

Custom Audio Products From Triad

Equipped with over seven decades of experience in the custom magnetics industry, the Triad engineering team has the skills and knowledge necessary to design and build high-performance custom audio transformers for the audio and sound processing industry. Whether a customer needs multilayer section winding or multi-electrostatic shields with interleaved windings, we can deliver a custom solution that meets their exact audio needs.

Some examples of custom products we produced in the past include:

  • A shielded audio transformer for sound processing. When approached by a customer looking for a replacement for their existing 30-year old component, we were able to design and build an exact replica that worked seamlessly with their legacy equipment.
  • A professional audio transformer. A company in the audio interface sector came to us with a request for a transformer suitable for professional audio applications. Using multi-electrostatic shields with interleaved windings, our team created a high-performance transformer that offered flawless harmonics.

To learn more about our standard and custom audio transformer offerings, contact us today. If you need help with your next project, our experts are here to help.

Food and Beverage Applications for Class 2/3 Power Transformers

Transformers convert alternating current (AC) from one voltage to a higher or lower voltage. Class 2 transformers are safer, more highly-rated electrical components frequently used in the food and beverage industry. Class 2 is a compliance rating which signifies that the power transformer meets safety standards that reduce the risks of fire or shock.

Essential features of Class 2 transformers include their safeguards against failure and their temperature control capabilities. The insulation used in these transformers enables them to withstand temperatures as high as 121° C without damage. Class 2 transformers also reduce the risk of shock by limiting harm from excess power.

The characteristics of Class 2 transformers make them an ideal choice for commercial food processing equipment. While all Class 2 transformers meet basic compliance standards, Triad Magnetics’ Split Pack™ transformers provide even better performance due to the increased focus on safety and innovative design.

Triad Magnetics’ PC Mount Split Pack Class 2/3 Power Transformers

pc mount split pack power transformers

Triad Magnetics’ Split Pack™ transformers are used to support a wide variety of PC board applications. These products feature split bobbin, or side-by-side transformer components. This is different from standard PC board transformers, which typically stack the secondary component on top of the primary one.

Due to this design change, Split Pack transformers may be used in series, parallel, or separate circuit configurations. Also, split bobbin transformers don’t require electrostatic shielding to protect the device, and the components in a series or parallel circuit have more secondary dielectric strength.

With Triad Magnetics’ Split Pack™ transformers, PC boards can be designed with unique circuit configurations that generate more power and control for industrial or processing applications in the food and beverage industry.

Applications and Solutions from Triad Magnetics

Screen Shot 2019-09-23 at 11.06.04 AMIt’s important to equip your food and beverage facility with the latest technology that will keep up with complex demands and give you greater capabilities than your competitors. Triad Magnetics supplies transformers and related components that enable facilities to perform at optimal levels with the highest quality. Our products are also designed to meet Class 2 and UL standards.

Some of our most popular components and their applications include:

  • Class 2 power transformers are often used to alter voltage levels to conveyor ovens and convection ovens.
  • Common-mode chokes block excessively high-frequency alternating current but allow lower alternating current and direct current through to devices. Deep fryers use these devices to control power input.
  • Control transformers are used in smaller appliances, such as coffee makers.
  • Current sense and PCB power transformers allow fast food egg cookers to sense electrical currents and change the alternating current’s voltage for safer operation.
  • Custom power toroids provide power to liquid/beverage dispensers in facility processes and customer-facing restaurants.

Triad Magnetics produces these and other electrical components to provide safer power control for applications across the food and beverage industry.

Transformers from Triad Magnetics


Transformers are vital electrical components in all industrial or commercial settings that have electrical equipment with varying voltage requirements. Food and beverage processing facilities, cold chain storage and distribution centers, restaurants, and other points across the food supply chain all need transformers that safely adjust voltage and protect against the risk of fire or shock.

Download our eBook, “Understanding UL Class 2 Power Transformers,” to learn more about Class 2 standards, the importance of transformers in various industries, and how to outfit your equipment and facilities with UL Class 2 power transformers. You can also request a quote today for Class 2 transformers for your food and beverage operation.

Download our Understanding UL Class 2 Power Transformers eBook

Autotransformer Power Transformers

What is an Autotransformer?

Autotransformers feature a single winding wound onto a laminated core. They’re similar to two-winding transformers, but their differences lie in the ways that the primary and secondary winding are interrelated. There are two varieties of autotransformers which may be differentiated by their construction.

  • In the first type, the transformer relies on continuous winding and taps are brought out at convenient points based on the desired secondary voltage.
  • In the other style of autotransformer, two or more distinct coils are electrically connected and form a continuous winding.

The Advantages of Autotransformers

Autotransformers present several advantages over traditional transformers, including:N-1X Autotransformer (1)

  • Lower cost
  • Improved regulation
  • Lower losses compared to standard transformers of the same rating

Autotransformers also save on copper when compared to two-winding transformers:

  • The weight of copper utilized for transformers is proportional to the length and area of a cross section of the conductor
  • Conductor length is proportional to the number of turns

The Disadvantages of Autotransformers

Despite these benefits, autotransformers are not without limitations. Some negative aspects of autotransformers include:

  • Only useful in limited applications which require a slight variation of output voltage from input voltage
  • If used to supply low voltage from a high voltage source, the full primary voltage may come across the terminal in the event of a break in the secondary winding. This poses a risk to operators and equipment.

Triad’s Autotransformer Power Transformers

Triad Magnetics offers autotransformers in step-up and step-down single winding models.

  • With step-up models the primary coil will only be a percentage of the full winding.
  • In step-down models, the secondary coil is a percentage of the full winding.

Any of our transformers can be converted to autotransformers by connecting all of the windings in series with each other. With fourteen different autotransformer power transformers to choose from, we have a model well suited to your needs. One of these models is a universal isolation/autotransformer/voltage control model which can operate at an output wattage rating of 4,000 output watts.

Creating Your Own Autotransformer Using Off-the-Shelf Power Transformers

All of Triad’s off-the-shelf transformers can be wired in a series or parallel combination to create an autotransformer. This is achieved by combining the primary of the transformer with the secondary to create a step-up or step-down transformer.

Before going into examples on how to wire an off-the-shelf transformer into an autotransformer, we must know how windings must be wired and why they must be wired in that manner. One end of the winding will have a dot indicating the start of the winding and the other end of the winding will be the finish.

The windings must be wired in phase. Phasing is important because it determines the direction in which the current flows. If the windings are wired out of phase, the currents from each winding would oppose each other causing a short within the transformer.

Take this schematic, for example:

schematic example

Each winding has its own pair of leads that are specified with different lead colors. The leads on the left represent the primary winding of the transformer and the leads on the right represent the secondary winding of the transformer. By wiring the primary and secondary windings in series, the transformer would be considered an autotransformer.

To wire the windings in series, the WHT lead would have to be wired to the RED lead. This will result in a single winding with the WHT/RED connection being a center tap and the BLK and YEL leads being the full winding. Wiring the two windings in series will cause the total voltage across the full winding to be the sum of the voltages of each winding.

For example, the primary winding is rated for 115VAC, whereas the secondary winding is rated for 12VAC. Wiring the two windings in series will cause the voltage of the full winding to be 127VAC. When making this type of connection, the transformer loses its isolation properties.

Below is another real-world example of making an autotransformer from a 4-winding transformer:

4-winding transformer

This can be done for applications that require a transformer with a 277VAC input. The schematic above represents the VPT48-2080. This transformer has two windings on the primary and two windings on the secondary. The four windings can be wired in series to make an autotransformer with a 278VAC output.

This can be done by wiring the following leads together: GRAY to VIOLET, BROWN to BLACK and RED to ORANGE.

Each series connection will accumulate the voltage for each winding. Wiring the 4 windings in series will sum up the voltages as follows: 115 + 115 + 24 + 24 = 278VAC.

For this example, we will make a 4-winding transformer into an autotransformer for applications that require a transformer with a 480VAC input. Below is the schematic for the medical grade toroidal transformer, VPM240-1040:


The 4 windings can be combined in series to make an autotransformer with a 480VAC output. This can be done by wiring the following leads together: BLU to BRNVIO to RED and BLK to YEL. Similar to the VPT48-2080, the voltages for each winding accumulate as follows: 120 + 120 + 120 + 120 = 480VAC.

For this final example, we will use the same schematic as the VPM240-1040. In this example, the primary windings will be wired in parallel, the secondaries will be wired in parallel and the two resulting windings will be wired in series. When windings are put in series, the voltages are added together and that sum is the voltage capability of the two wired windings. For windings have the same current rating, the current capability doubles when they are wired in parallel.

The different connections for parallel and series are as follows:

·         Primaries in Parallel: BLU to VIO and WHT to BRN, WHT/BRN and BLU/VIO is the full winding rated for 120VAC.

·         Secondaries in Parallel: BLK to ORG and RED to YEL, BLK/ORG and RED/YEL is the full winding rated for 120VAC.

·         New Primary & New Secondary in Series: BLU/VIO to RED/YEL, WHT/BRN and BLK/ORG is the full winding rated for 240VAC.

Making these connections doubles the power rating of the transformer due to the higher current and voltage capabilities. The autotransformer made from the VPM240-1040 will now have the capability for a 240VAC input and a current of 2.08A. The product of the voltage and the current is 500VA as opposed to 250VA as an isolation transformer.

Depending on the difference between the input voltage and the output voltage, the power rating will be affected. For instance, if the difference is higher, the power output will be lower and vice versa.

Safety Considerations

The main safety consideration when making an autotransformer from an isolation transformer is the loss of isolation. The isolation is lost due to the direct connections made when combining windings in series or in parallel. The output of the transformer would then be referenced to ground and making contact with the connection can be harmful or even fatal.

When making an autotransformer from an isolation transformer with multiple windings, it is important to take into account the current rating of the windings. We must be mindful of the current ratings for each winding to ensure that the transformer does not heat up excessively, or, in some extreme cases, melt the magnet wire insulation, causing a short. The current rating for the autotransformer should be limited by the lowest rated current winding.

Transformer Solutions from Triad Magnetics

Triad Magnetics has more than 1,000 part numbers for customers to select from and we offer a pioneering design process that fosters innovation and growth. These factors, along with world-class manufacturing and steadfast commitment to quality and reliability, position us as the number one choice for all of your transformer needs.

Interested in learning more about transformers from Triad Magnetics? Contact us today or request a quote for further information.