Series One Dual Patents

Dual Patent Design

The cornerstone of the Series One design is the two patented circuits: the ISF (Infinite Shape Feature) tone control circuit and the DPR (Dynamic Power Reduction) power reduction system.

These technologies are exclusive to Blackstar Amplification and are the result of many months of in-depth technical research. The inclusion of ISF and DPR allows you to take the Series One’s highly developed sound palette and tune it exactly to your own sound signature and create ‘the sound in your head’.

ISF and DPR are perfect examples of Blackstar innovations that, through technical research and development, can significantly improve your performance and creativity as a guitarist.

DPR (Dynamic Power Reduction)

Everyone knows that valve amplifiers sound best when they are turned up loud. This is because at higher volume levels the output valves introduce musical distortion and compression which are a vital part of the valve amplifier experience.

Blackstar’s patented DPR feature controls the output power level by dynamically adjusting the output stage voltages, allowing power valve distortion and compression at any volume level.

Obviously, the fact that valve amps sound best when they are operated at full power means that they can be impractically loud.

Series One DPR Knob

Benefits of the DPR control:

1. DPR allows continuously variable power reduction, down to 10%, so you can use your valve amp in any playing situation.
2. DPR is a ‘dynamic’ circuit, delivering the exact compression (a.k.a. sag) of a small overdriven valve amp, at any volume level.
3. Unlike power attenuators, DPR places nothing between the output of the amplifier and the loudspeaker and hence as the power is reduced the feel, tone and reliability of the amplifier is maintained.
4. DPR’s dynamic power reduction is only available on Blackstar products.

Series One DPR Logo

ISF (Infinite Shape Feature)

The conventional three way guitar EQ network, or tone stack (a.k.a. Bass, Middle and Treble), is a key to the characteristic ‘voice’ of traditional guitar amplifiers. Classic amplifier designs have their own versions of this network which leads to their own tonal voicings.

The ISF control allows you to infinitely adjust the response of the tone control network between any of the traditional voicings in a way that has never before been possible.

Importantly the tone controls remain interactive in the same way as a traditional guitar amp tone control network. For example a change to the treble control will affect the depth and centre frequency of the middle control – this yields a very musical feel to the tone controls.

In this way you can design your own sound and truly find ‘the sound in your head’.

Series One ISF Graph

Benefits of the ISF Control:

1. ISF is a passive circuit giving a musical response that is not found in active parametric or 'contour' controls.
2. The whole tone stack response (i.e. Bass, Middle and Treble) is moved.
3. The tone controls remain fully interactive, just like in a regular tone stack.
4. The ISF control is continuously variable between all the traditional responses allowing you to effectively design your own sound.
5. ISF and ‘the sound in your head’ are only available on Blackstar products.

Series One ISF Logo
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