Some collaborations in audio are more than technical partnerships. They become part of sound history.
For Lundahl Transformers, our long-standing connection with Focusrite is one of those stories. It goes all the way back to 1985, when Beatles producer Sir George Martin asked Rupert Neve to design a no-compromise microphone preamp and EQ for the Forte console at AIR Studios in Montserrat. The result became the ISA – Input Signal Amplifier – a design that would become one of the most respected microphone preamp families in professional audio.
At the heart of that original ISA microphone preamp was the Lundahl LL1538 transformer. And almost 40 years later, it is still there.
The transformer behind the ISA sound
The Lundahl LL1538 has been used in every Focusrite ISA microphone preamp since 1985. For us, that is something we are deeply proud of. A transformer is often hidden inside the product. It is not always the part you see first. But in high-quality audio design, it can have a major influence on how a circuit behaves, how a microphone interacts with the preamp and how the final signal feels.
The LL1538 became part of the ISA sound because it offered something that great engineers and producers continue to look for: openness, detail, musicality and reliability.
It is a small component with a long story.
From AIR Studios to modern recording workflows
The original ISA design was created for a world of large-format consoles, world-class studios and analogue recording sessions. It was a time when every part of the signal chain had to perform at the highest level.
Today, the studio landscape looks very different. Engineers, producers and creators work in professional studios, project studios, home setups and hybrid environments. Workflows are faster, more flexible and increasingly digital.
But the need for a great analogue front end remains.
That is why t
he new Focusrite ISA C8X feels like such a natural continuation of the ISA story. It brings the classic ISA sound into a modern 26-in / 28-out USB-C audio interface, combining analogue character with the control and flexibility expected in today’s studio environment.
The first two ISA preamp channels in the ISA C8X feature Lundahl LL1538 transformers — carrying the heritage of the original ISA design into a new generation of recording technology.
Lundahl inside
For Lundahl, seeing the LL1538 continue to be part of the Focusrite ISA range is both an honour and a reminder of what long-term engineering partnerships can become.
Our transformers are designed and manufactured in Sweden, with a focus on precision, consistency and sonic integrity. Focusrite’s continued use of the LL1538 shows how a carefully chosen component can remain relevant across decades of product development.
From the original ISA modules to modern studio interfaces like the ISA C8X, the same idea remains: to preserve the musical quality of the source while giving engineers the tools they need to shape sound with confidence.
A proud part of audio history
The Focusrite ISA C8X is a modern product, but it carries a heritage that began in one of the most iconic chapters of studio recording. For us, this is not only about one transformer in one product. It is about trust built over time. It is about craftsmanship, engineering and the pursuit of sound quality. It is about how a component made in Sweden became part of a globally recognised audio legacy.
Almost 40 years after the first ISA preamp, the Lundahl LL1538 is still helping shape the sound of Focusrite ISA. And we are proud to be part of that story.
Discover the Lundahl LL1538
The Lundahl LL1538 is a high-performance microphone input transformer used in professional audio applications where sound quality, reliability and long-term consistency matter. Explore the LL1538 and learn more about how Lundahl transformers are used by leading audio manufacturers around the world. Datasheet 1538