Forward Thinking

An in-depth look at the ASTRO-20

Tube Life

ASTRO-20 Forward Thinking


The ASTRO-20 includes state of the art circuitry designed to protect and increase the power tube’s life. It’s common practice for amps to use DC heaters for the preamp tubes primarily for noise reduction. The ASTRO-20, however, uses DC power for BOTH the preamp tubes AND the power tubes! When powered ON, tubes start from a COLD state with very little resistance. The shock of turning them ON acts like a short circuit and this abuse, over time, can shorten the tube’s life. To protect against this the ASTRO-20 includes state of the art current and voltage monitoring circuitry which precisely limits the startup current and accurately sets the voltage of the tube’s ideal operating point. This protection dramatically increases the tube’s life and to our knowledge is not available on any other guitar tube amplifier.

Latency Matters

ASTRO-20 Forward Thinking


The ASTRO-20 combines all tube tone with a powerful digital engine for impulse responses and power amp simulation. The oversized 500 Mhz ARM DSP processor is utilized solely for these two functions resulting in performance that is vastly better than competing products. How good? 50ms Impulse Response length in under 1ms of latency! This is compared to most products today which are only capable of achieving 20ms IR length at 1ms latency. At 20ms length the resolution is only 48hz, meaning the impulse response will mostly sound the same under 150hz – these are the critical frequencies where “punch” lives. Mike Soldano has earned a reputation for forward thinking with no compromises – the ASTRO-20 best in class digital engine delivers on that promise.

Universal Voltage

ASTRO-20 Forward Thinking


Mike Soldano designed the ASTRO-20 to work seamlessly anywhere in the world with the help of a voltage selector switch found on the back panel. This simple and useful feature is not common on most tube amps but is on the ASTRO-20. This is made possible thanks to Mike’s state of the art current and voltage monitoring and the cathode self-biasing circuits. When traveling or moving to a different country and want to take the ASTRO-20 with you, there is no need to re-bias the amp or use a step-up/step-down transformer – just select the right voltage, replace the Mains fuse with the correct rating and you’re ready to go!

Dont Standby

ASTRO-20 Forward Thinking


Mike Soldano is known for challenging convention and when designing the ASTRO-20 he started from the ground up, re-examining every aspect of his new design, even including the traditional Standby switch. A Standby switch is needed when the power supply uses capacitors whose maximum rated voltage is very close to the operating voltage. When tubes are cold and the current drain is low, the operation voltage may exceed the maximum capacitor rating voltage which is where the Standby switch comes in.

To address this Mike selected for the ASTRO-20 capacitors rated at a much higher voltage than normally needed. This provides additional safety and less stress on the capacitors, translating to increased longevity thereby removing the need for a Standby switch.

No Load

ASTRO-20 Forward Thinking


When Mike Soldano first designed the now legendary, Super Lead Overdrive (SLO), he wanted a design that didn’t rely on the power amp’s distortion, which is how every other amp was doing it at the time. His innovative and now famous cascading tube stage preamp design was paired with an extremely clean and hi-fi power amp, resulting in one of the most famous amp designs of all time.

Following that same philosophy, the ASTRO-20 combines Soldano’s legacy tube tone with the best DSP technology available for cab-less operation. Rather than loading down the power amp with a reactive load, the ASTRO-20 takes the signal right at the phase inverter and uses the extraordinary power of the 500Mhz ARM DSP engine to create a DYNAMIC load – both for the speaker and power amp response. During cab-less operation the power tubes are automatically disconnected and placed in a safe mode thereby preserving the life of the tubes.

The commonly used reactive load only provides two representative points of a true speaker, giving a similar but not fully accurate representation of the response. Thanks to the powerful digital engine, in addition to the fact that SOLDANO design doesn’t rely on power amp distortion, the ASTRO 20 is capable of recreating more than 2000 reference points – giving a true “high resolution” response.

Designed Better

ASTRO-20 Forward Thinking


In addition to a modern feature set and killer tone, Mike Soldano engineered the ASTRO-20 using the finest components and technology available, considering quality and ease of servicing. It’s the same way every Soldano product is designed, but the ASTRO-20 takes everything a step forward.
As will all Soldano tube amps, the ASTRO-20 amplifier and Baltic birch head shell are proudly built in the USA. We wouldn’t have it any other way.

The ASTRO-20 is constructed using three circuit boards that are linked by a SINGLE connector (with a few separate shielded signal connectors designed to minimize crosstalk). This meticulous PCB layout design provides the best possible signal to noise ratio and makes it extremely easy to service. To top things off the circuit boards are gold plated!

All accurately spaced components are industrial grade, while key components are automotive grade. This means that ALL the components used for the digital part of the design are guaranteed to be available for at least 15 years. All resistors used are at minimum 1W with low 1% tolerance and the branded capacitors, relays and tube sockets (WIMA, Nichicon, Belton) are of some of the finest available.

In addition to safety testing, the ASTRO-20 passed severe thermal stress tests, meaning all components work at their ideal temperature even under extreme use. It’s fair to say the ASTRO-20, at least from an engineering perspective, is literally cool!

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