ASAR Grand Slam


Alter Sonus Audio Research (ASAR)

High performance guitar clean booster, belongs, evidently, the elite series of objectives can be reached only by means of a completely handmade building. Is expressly dedicated to more demanding guitarists, which in addition to a pedal able to best perform the functions typical of the booster, would like to be able to elevate along with the level of the signal coming from the pick-ups, also the overall quality and the class of entire system guitar/effects/amplification. The advanced circuitry, entirely by discrete and selected JFETs (no chips/op amp), consists of:

  • An input stage, which in addition to amplify the signal preserves even the most subtle nuances of timbre and dynamics, without altering them, even without the interference typically due to hiss and hum; a properly boosted signal can really afford to work at the best the amplifier, which can/should be lowered in proportion the GAIN control, with the results that you can see through the YouTube demos already linked to this  announcement;
  • FOCUS control, which does not interfere appreciably in the high frequency range, always evident, clear and defined, serves to focus the best "quantitative" response on bass and mid-bass in any context, even synergistically assisted by other controls on the amplifier, such as BASS and DEPTH. Thanks to GRAND SLAM is unlikely that you will still have to complain about bass present but not sufficiently damped (or rumbling and regurgitating), or, conversely, quite subdued and controlled, but too little present (no punchy);
  • A buffer circuit not less evolved of the input stage, which lowers the impedance of the output signal without distorting or compressing it and without appreciably reducing his amplitude.

Why circuitry entirely JFET?.. Low hiss/noise, high input impedance, timbre footprint particularly similar to that of triodes. However, JFETs are affected by a pronounced dispersion of the characteristics relative to one another, for the same symbol. For a craftsman is however not a problem to test many, one by one, and select them accordingly, as is in my case.

As is normal, the activation of the pedal is through the insertion of the input jack and this is indicated by the red LED. The green LED light up only when the pedal is “BOOST ON” via the footswitch.

The internal battery is excluded, automatically, when you insert the jack of the external power supply and if it were to have the wrong polarity, the circuit will not be damaged, due to robust protection installed.

Is, also, needless to employ power supplies with voltages higher than 9V, because the circuit does not receive more thanks to another protection, specially provided for the purpose.

Supplies that provide more than approximately 11V actual represent only an unnecessary work for these protections.

Every booster pedal is individually built, developed, tested, and then internal numbered. Every unit have an alkaline battery inside (6F22 type), in gift with the booster. The wiring is, of course, TRUE BYPASS, performed with professional shielded OFC cable, while the components are almost entirely housed on PCB.


  • ALPHA and CTS 24mm potentiometers;
  • Fairchild JFETs;
  • Panasonic FC, Frolyt ERF, SILVER MICA, WIMA MKP, Roederstein MKT 1818 capacitors;
  • Features:
  • The total power consumption of the circuit, with both LEDs lit, is 5.5 mA (about 50 mW).
  • Input impedance: higher than 1 MOhm.
  • Output impedance: lower than 500 Ohm.

The enclosure dimensions, die-cast aluminum, are 146x120x38mm (5.70 x 4.70 x 1.50D inches) and it is the smallest possible that could adapt to this project. The primary objective was, however, achieve the best sonic performance, with reliability and low noise.

Use the GRAND SLAM will be an opportunity, also, to get a tangible idea of the projectual philosophy, beliefs and goals that AlterSonusAudioResearch seeks to achieve, proposing soon even more products, more challenging and  existing at the prototype stage.

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