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Genz Benz Shuttle Max 12.2 Peak Indicator lamp

Discussion in 'Amps and Cabs [BG]' started by bstark, Oct 12, 2012.

  1. bstark


    Sep 8, 2012
    Seattle WA
    I'm enjoying getting acquainted with my new Shuttle Max bass amp. I need some help understanding more about this incredible machine.

    The owner’s manual discusses the amber peak indicator lamp and when it lights up. It says "The amber PEAK LED indicates that the power amp has reached maximum power." I have the Low Gain pushbutton set to low gain, the Input Gain set to prevent any indication in the Input O/L LED, and the Master Volume is set really low (about 9 o'clock), I notice the Peak LED consistently lights up whenever I turn up the EQ on the lowest bass frequencies. This occurs with the active equalization and/or the global signal shape sections.

    I'm confused about this behavior because intuitively I would reason that with a clean input signal from my bass and by turning the master volume way down, I could turn the bass EQ way up and this LED won't light up. This is not my experience. Turning the bass down causes this indicator to stop lighting up.

    Are bass frequencies inherently harder to process and amplify? Does the Shuttle Max have some sort of special load sensing circuitry that can sense and report speaker distortion that loud bass frequencies are sure to produce?

    Educate me, please.


  2. The master volume knob does not regulate the actual power output of the amp. You can easily reach full power at even low master volume settings (on any amp) by really cranking the gain, or adding a lot of low end (which eats up power, hence pushing the power amp).

    The good news about the Genz power amp indicator light is that it is more of an indicator of the power management circuitry kicking in (which actually sounds good... kind of their gently compression 'all tube emulation') versus a 'danger' light like on some other amps.

    So, what you are seeing is 'normal', assuming that the result is stupid loud, which it should be:p
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Ken's description is likely what you are experiencing. Extended or boosted low frequency material takes a lot more power to reproduce, and at the same time the speakers become less efficient as the frequency gets very low. YOu will also want to be careful when doing this because there are some combinations where you could possiby overdriver the eq or filter stages, that would typically be with thegain and channel volume up very high and the master volume very low. This would not be a normal or very useable way to play any amp however. The channel clip LED will sense eq section overload but not the shape filter overload if you are using LF extreme boost/extend.
  4. bstark


    Sep 8, 2012
    Seattle WA
    These explanations make sense to me. I suspected that low frequencies take more power to process. That boosted low frequency material could go through the EQ sections and cause distortion as registered on the Peak LED. This happens even if the master volume is at a low setting.

    I'll keep this in my mind as I find my bass sound on this new amp.

    Thanks for the lessons.

  5. The max heads are very articulate, and a bit bright set neutral out of the box.

    Don't try to make up for the brightness (if that isn't your thing) by overboosting bass. The hi mid control, with the freq set at around 1K or 2K (can't remember the range on that.... probably with the freq control at about 1 o'clock) and cut a bit (or a lot, if you want to 'old school it up'), combined with a very slight boost on the very nice bass control (shelving starts at around 80hz I think, with nice true hi passing in the sub bass) will give you a very even, tight but full tone that isn't over goosed in the upper mids.

    Now, use the wonderful variable bass filter to dial in just the amount of deeper low end you want without blowing up the low end control.

    Really nice. Enjoy the head!
  6. wmheilma


    Jan 5, 2010
    I have the ShuttleMAX 6.0 and can say for sure the amp sounds fine with the Peak LED coming on occasionally. (The circuit may be slighlty different in the newer .2 models.) The LED typically lights up if I crank either the highs or the lows excessively, but unless it is on pretty steadily the amp sounds great. Clipping a Class D amp is very unmusical, so this light is a good indicator of when to stop cranking things up.

    I have noticed that the LED can light more liberally without audible clipping when I am running the head into an 8 Ohm load compared to 4 Ohm load.

    I am still thrilled with my GB and have been playing it almost two years now. My gig bag for it is falling apart, so I added more padding inside. I use the foot-switchable shelving EQ a lot!