Twin-Iso™ Development


Understanding the Twin-Iso

Ask any sound tech what frustrates them most about their job and they will tell you that it is likely 'solving noise problems on stage'. One can often solve hum and buzz problems by introducing an isolation transformer in between two pieces of gear.

Back in the early days of audio, just about every piece of audio gear was transformer isolated. But over the past several decades, there has been a noticeable shift away from transformers to more affordable electronically balanced inputs. Good transformers are expensive. These low-cost alternatives yield tremendous 'bang for the buck' but do so at the expense of greater susceptibility to noise. In the real world, (outside of the laboratory), 'perfectly balanced' signals are often compromised due to imperfections in wiring, less than ideal power distribution and differing ground reference voltages from equipment. The result is hum, buzz and noise caused by ground loops.

Transformers eliminate hum and buzz problems and since today they have become an option that is only found in very high-end gear, the Twin-Iso presents itself as a 'welcome relief' for the informed tech.

Transformer Magic

Transformers are magical. A signal goes into a primary winding which generates a magnetic field. The metal core inside acts like a conduit, sending the magnetic field into a secondary winding, producing current on the other side. Because the signal travels across a magnetic bridge, you can disconnect the ground between the two pieces of equipment. The result: the ground loop disappears along with the dreaded buzz and hum. Happier artist and a happier tech.

But alas... not all transformers are created equal. Deane Jensen wrote the book on audio transformers and in the early 1980s discovered that the core material dictates how well the transformer will perform. It has to do with the permeability of the metal being used. Permeability refers to the metal's ability to become magnetically charged and then go back to a 'ready state' without retaining a magnetic memory. Nickel has a much higher permeability than steel.

Following Deane Jensen's pioneering, the Jensen transformer inside the Twin-Iso employs nickel laminations. These are stacked in a proprietary sequence to achieve maximum performance and the coils are wound in a careful sequence to ensure optimal signal transfer. In fact, we employ a very particular transformer design that is able to handle tremendous signal levels without distortion.


Transformer Frequency Response

Distortion versus saturation

Active circuits or buffers are limited by the headroom that is available. In other words, if you exceed the operating levels set by the circuit design, the signal goes from zero to 100% distortion instantly. This is known as clipping or square wave distortion. What few realize is that low frequencies contain much more energy than high frequencies. In basic terms, this means that real audio performance is measured by looking at how the device is able to handle bass. Something that may 'spec out' at 0.5% distortion at 1000Hz may in fact have 10% distortion at 20Hz. In transformer-land the physical size of the transformer often dictates the power handling. Look inside a bass amp and chances are, it will have a big fat transformer.

The Twin-Iso is no different. The Jensen transformers inside are huge! The larger size generally means that the transformer is able to withstand more signal before it overloads. And this is one of the tremendous attributes that transformers bring to the table: they do not 'distort' like an active circuit, they 'saturate'. And good ones saturate in a nice even fashion whereby as they reach their saturation level, they naturally compress the signal. This is often referred to as sounding 'vintage'. This makes sense considering most vintage gear employ transformers.


The Jensen Transformer Intermodulation Distortion vs Output Response

Extreme level handling

The Twin-Iso is actually capable of handling signals in excess of +24dB. Considering that most pro gear is designed to produce +4dB, the Twin-Iso has tons of headroom. In fact, the +24dB output is measured at 20Hz which means that at 1kHz, it will likely deliver +30dB without a problem. This type of level handling matters when you are interfacing high output devices such as mixing consoles, crossovers and delay towers where amplifying audio with thousands of watts can sound horrific when distorted.

Built Rugged for the Road

As with all Radial products, the Radial Twin-Iso features a rugged 14-gauge steel construction for maximum durability to stand up to the rigors of pro-touring. The unique bookend design provides a protective zone for the switches while the full bottom no-slip pad provides plenty of 'stay-put' for more active stages. The unique design features welded I-beam construction, making it practically impossible to torque the internal PC board. This reduces the opportunity for solder joints to fail due to outside stress. This also permits up to eight Twin-Isos to be rack-mounted using the Radial J-Rak™, or one can be permanently mounted to a case or rack using the J-Clamp™.