MusicRadar

These new Series One heads are built to superb standards and represent excellent value for money.

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• Review

Over the past decade, Blackstar has developed into one of the world's leading amp manufacturers with an expanding artist list of top players, a recent Queen's Award for Enterprise (for international trade) and over 30 employees now based at the company's Northampton HQ.

Clearly a company that doesn't do things by halves, Blackstar has recently expanded its bestselling Series One range with three new heads: the four-channel S1-104 in EL34 and 6L6 versions, and the simpler two-channel S1-50.

Let's dive straight in and see how the new additions perform. All three heads have the same Blackstar look and feel: solid plywood sleeves neatly covered in hard-wearing vinyl, wire mesh grilles and steel rear panels combined with a black control panel featuring an intuitive layout and effective graphics.

The build standard is very high and the attention to detail stands up to the closest of inspections, with touches such as the embossed leather carry handle and two-tone corner protectors leaving one in no doubt that these are serious pieces of pro-level equipment.

This is further reinforced if you look inside the deep steel chassis: the Series Ones are built on printed circuit boards that are laid out and produced to an exceptionally high standard.

There are five main boards, including two for the front and rear panels and three more for power supply, preamp and power valve bases. Wide tracks for audio signals combine with top quality components: one PCB is dominated by a large alloy heatsink that cools the devices used in the Series One's Dynamic Power Reduction circuit.

All the boards are joined together using Molex-style connectors, but with individual wires rather than the more common ribbon cable - this adds significantly to reliability and ease of servicing/fault diagnosis.

All three heads are large and very heavy, thanks to massive mains and output transformers. They could balance better on their carrying handles when picked up, but that small criticism is all we can find.

Overall we're very impressed - the Series Ones combine audiophile valve know-how and digital expertise with rugged reliability and good looks, while the manufacturing standard of its Korean plant easily exceeds that of many European and US-built products.

The two S1-104 amps are proper four-channel heads, with four pairs of gain and channel volume controls feeding into two sets of EQs: one for clean and crunch and the other for the two overdrive channels.

The clean channel features a bright/warm switch that also reconfigures the output stage to run in class A or Class AB to further emphasise the different characters. Similarly, the crunch channel can be run in normal and super crunch modes, the former providing a lower gain crunch with a looser feel, while super crunch boosts the gain and tightens up the damping for a modern crunch metal tone.

In addition to bass, mid and treble, both EQs have Blackstar's ISF control, which progressively morphs the tone circuitry from British to American values, significantly expanding the amp's sound shaping abilities.

"The build standard is very high, leaving one in no doubt that these are serious pieces of pro-level equipment."