GenzBenz L.F. - Filter Question

Discussion in 'Amps and Cabs [BG]' started by TheRealKong, Jul 7, 2013.

  1. TheRealKong


    Mar 17, 2011
    I have heared a lots of good things about using a HPF. It protects the speakers and takes away some boomyness from the low, low end.

    I also literally have seen a lots of good things about HPF. When attached the excursions of the speakers are more controlled. You don't waste a lots of power in uncontrolled speaker movements. If your cab has no grillcloth you can see this.

    The first stage of GenzBenz-amps has two low-cut-points at 23 and 20 Hz according to the manual. OK, so the subsonics will be under control. :bassist:

    I am interested in the function of the L.F.-Extend - Filter, that "lowers the low frequency roll off response of the preamp (between 30 and 45 Hz) to allow the full effect 0f 5+ and extendet scale instruments", thus sayed the manual. :D

    Does the LF-Filter work like a HPF? And: In which direction have I to turn the knob to have a roll off at 45 Hz, which direction lowersd the roll off? As my GBE is firing up a Tecamp L 810''-cab whith a massive low end it is difficult to hear this, at least there is no audable effect when turning this knob while playing a 5-string bass.

    Thank you for any help.


  2. It is a combined 'bass boost/Hi Pass Filter' in a single knob on the Max heads, and an 'all or nothing' on/off button on the Shuttle heads.

    Very nice... according to many posts by Agehorse (Genz engineer) and lots of listening on my part:D, it lowers the frequency range from around 35hz (off) to around 30hz (full on with the Max heads, and also boosts the volume of the deep low end). So, the entire range of the knob is pretty subtle, and it is not a pure 'variable hi pass' like the nice FDECK pedal.

    On the Max heads, the more you turn the knob up, the hi pass gradually lowers while the general low bass frequencies are boosted.

    If your TecAmp 810 cab is sealed, it might not be putting out much below the 'off' position on the LF filter, which is why you aren't hearing much. It is highly impactful on the cabs I own, even my little Berg AE210.
  3. To answer you question directly, the 'tightest' low end is with the filter turned off (button 'out' on the Shuttle, or knob all the way counterclockwise on the Max... or the 'engage' button off).
  4. TheRealKong


    Mar 17, 2011
    Thank you, KJung. This helps a lot.

    No, the L 810'' is ported and produces a massive ammount of low end. I barely touch the Filter knobs when going on stage, because this often ends up an a massive twiddeling orgy. I just cut the lows if I am on a boomy or hollow stage. Maybe I cannot hear any effect because the rehearshal room is small and stuffed with things. We are moving to another room soon, maybe there it is better audible.

    So if I did get it right, the highest LowCut (45Hz says the manual) is with the L.F. turned out or full counterclockwise, for more lows (down to 30 Hz) go clockwise.

    Thanks again, it helped me understanding the pre of this great amp a bit more. :D


  5. Yes, in your situation, you will most likely always leave all three filters 'off'. That will result in the most even response, tightest low end, etc. The low mid semi-parametric is your friend for punching up the low mids relative to deep bass. The shelving bass control is also nice and punchy, impacting frequencies (I think) 80hz or so and below, up to the hi passing of the amp.

    My guess is, the filters off, bass control at noon, and the low mids punched up around 100 hz or so should work for you quite well.

    Also, +1 that a big cab in a very small room can be a mess!
  6. PS Andy has not been on this site for a while, but you might try PM him (agedhorse). He is very helpful, and will give you the exact scoop on the frequencies impacted by the LF filter.
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I've been on the road the past few days, great sound gig last night with some really seasoned pros (and nobody under the age of 35 on the touring or local tech crews... yay!) Things will get a bit spotty as I'm out again for a 3 week run of a horse entertainment event that I produce a segment for.

    It depends on which model amp you are talking about, but in general on all of our amps, the LF boost switch does 2 things at the same time. The HPF shifts downward and a slight amount of compensating boost gets inserted, this helps compensate for what happens at the 3dB point of the acoustic rolloff of many speakers. The total boost is very small (IIRC around 2-2.5dB) but the combination really helps the performance of larger and more capable cabinets.