Solid-Tube Design

Years of experience have shaped the founder's preferences towards one technique versus another, and along the way, some discoveries have been made too. One which we patented and called Solid-TubeTM. Although this page does not contain any trade secrets, it does describe the principle of Solid-TubeTM.

What is Solid-TubeTM

Solid-TubeTM is a technology we discovered in October of 1998 initialy designed for our next generation of amplifiers. It offers extremely open sound stages while keeping the neutral, accurate and natural sound of a live recoding. Solid-TubeTM is a new and clever combination of various transistor technologies each working at hiding the shortcomings of the others while extracting only the most desirable linear characteristics of each.

Why Solid-Tube

Common amplifier design operate in a closed loop configuration. This means that there is a feedback loop where a fraction of the output produced by the amplifier is compared to the input signal and a residual error is injected back into the amplifier to compensate. We conducted more simulations, test prototypes and subjective listening sessions than we can count, all of which demonstrated, time after time, that a non linear amplifier whose loop is closed does not sound as good as a linear amplifier with a similar band pass and gain in a closed loop (and sometimes even in open loop). Although the difference is hardly measurable, this phenomenon seems quite logical.

We have spent an incredible amount of time during the design of our amplifier stages to achieve the most linear possible transfer function in open loop. Birdland Audio's Solid-TubeTM technology is a result of this relentless quest for linearity, and the purity of the sound quality is a testament to that nutured research.

How does it work

Solid-Tube employs a combination of multiple transistor technologies, namely jfet, mosfet and bipolar, where each technology is working at extracting the most desirable linear regions of another technology while hiding the undesirable characteristics. This aproach is not totally new for some known designs do take this route. The Cascode assembly is a well known example of this - but never before did anybody try the combination we call Solid-TubeTM which employs three technologies. The Solid-TubeTM analog design is extremely linear and highly immune to power supply noises, a heavenly characteristic seeked by every audio designer.

What does it sound like

Because Solid-TubeTM results in extremely linear stages which exhibit outstanding characteristics, it virtually disappears leaving the sound almost un-touched. It is experienced as a very natural and extremely open sound stage where the system disappears to leave only the music. Yet this transparent sound comes with a touch of warmth otherwise found in tube electronics.

It was named Solid-TubeTM because it is mainly based on solid-state technology but it reminds of the Tube designs in that the result is extremely transparent and open.

Who uses it

Currently, Solid-TubeTM is our proprietar technology and is only being used in our products although, we have been considering licencing the technology to third party interested in OEM integration with their products. Please contact us if you are interested in including Solid-TubeTM technology and sound in your designs.

Gilles Gameiro - Birdland Audio

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