Kala UBass live sound problem

Discussion in 'Live Sound [BG]' started by Colin Maddocks, Feb 25, 2018.


  1. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    I have a residency at a live music pub in central Liverpool. It has a house PA that I go through with my U-Bass with Pyramid steel strings. However, I face a constant battle when playing straight into the desk in that one particular bass note (an F) results in a really loud booming, (almost feedback) which reverberates through the large room and if left unchecked results in feedback. Plus it makes it almost impossible to play smoothly as I'm constantly fighting the boom on F notes.

    I've taken ALL the bass and middle off the channel on the desk and all the bass off my bass but still get that boom. Plus the sound of the bass then is very toppy and I get an audible click when playing the strings that you can hear through the PA.

    I wondered if anyone could suggest way around the problem?
     

  2. Parametric EQ, either built-into the console or an outboard unit. Dial in a bandwidth of about 1/6-octave, cut about 8-10 dB. Play that F-note and then sweep the frequency knob. When it hits the right frequency, it will suck the “boom” right out. Once you find the right frequency, you can then tweak the bandwidth and dB cut.

    Regards,
    Wayne A. Pflughaupt

    Ecclesia: Unique Arrangements of Hymns, P&W Standards, and Original Tunes
    Administrator, Pedulla Club #45
    Administrator, Tobias Club #133
    Fretless Club #943
    Big Cabs Club #23
    My Rig: Stage and FOH Friendly
    My Basses


     
  3. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    Thanks Wayne. As a technophobe (!) can I ask if that would be possible by buying and placing a Parametric EQ to put between my U-bass and the desk?
     
  4. saabfender

    saabfender Inactive

    Jan 10, 2018
    Indianapolis
    It’s the room. The only real solution is to get with the owner of the venue and encourage him to incorporate some acoustic treatment into the space. It’ll not only help that one issue with the F but make it a more acoustically pleasant space in general.

    EQ is not the answer. You’d be better off just not playing the note.
     
  5. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    Sadly the owner/s of the room wouldnt' do anything I'm afraid. They are great people but wouldnt' do anything, I know that.

    I've tried not playing the F (or playing it quickly and trying to damp the note almost immediately) but it's almost impossible as you can imagine.

    Would something like a Fishman Platinum Pro EQ not help? Sadly the room alterations just wont' happen.
     
  6. saabfender

    saabfender Inactive

    Jan 10, 2018
    Indianapolis
    The acoustic reality of the situation is just too great. If you were to do a sweep of the room, you'd probably find a peak of around +12-16dB on that frequency. Any analog EQ solution that will get you in the ballpark will mess up the adjoining notes as well, making them nearly disappear in context.

    Yes, I can imagine. My deepest sympathies.
     
    Colin Maddocks likes this.
  7. saabfender

    saabfender Inactive

    Jan 10, 2018
    Indianapolis
    If you could get some panels in one or two corners of the room, you might have a fighting chance. Anything to "stuff a rag in the horn" those corners create.
     
  8. JRA

    JRA my words = opinion Supporting Member

    i agree with both solutions. buying a parametric could be an advantage in other rooms/gigs as well. but using a parametric to 'notch out' a particular frequency (sounds to me like you're dealing with a problem around 43Hz or so) is a common use for that gadget. of course you have to keep in mind that you get what you pay for (EQ's) so a parametric may or may not be worth the expense.
     
    Colin Maddocks likes this.
  9. Wasnex

    Wasnex

    Dec 25, 2011
    There are lot's of preamps designed for use with acoustic electric instruments that have a built in notch filter. Google "preamp notch filter" Also if your Kala is one of the "acoustic electric" versions you may need a sound hole plug U-Bass Feedback Freezer - Kala Brand Music Co.


    If the house PA has a 31 band graphic, it may be beneficial to dip one or two bands that are most adjacent to the problem frequency. Dipping octave harmonics and subharmonics can also be beneficial.
     

  10. Yes indeed! You’ll want a pro-audio unit that has bandwidth, frequency and gain controls for each filter – the Fishman you linked doesn’t appear to have the critical bandwidth control.

    The bandwith adjustment lets you determine how wide (or narrow, in this case) you want the filter to affect. With a narrow enough filter, these things have surgical precision – you can EQ a single note on the neck! No kidding, I’ve done it. With the method I mentioned above you can get in the ballpark. Then you can tweak the bandwidth control to make sure you‘re only notching the offending note and not the ones adjacent to it. You can't do that with a graphic 1/3-octave EQ - they cut too wide a path.

    I’d suggest an analog unit. Digital models “step” the frequency selections, say 1/25-octave, which means you can select only one of 25 frequencies in a given octave range. Analog models have a continuous sweep on the frequency knob, so you can precisely nail the offending frequency – again, with surgical precision.

    No one hardly makes any analog parametric EQs anymore, so you’ll have to get a used one. For a while they were practically giving them away, since capable parametric EQ is built into digital consoles these days. But prices seem to be going back up – I guess people are re-discovering their usefulness.

    Ideal models you can get fairly cheaply would be a Symetrix 551, Rane PE-17 or Ashly 571 / PQ16 (but the Ashly’s often cost more). Since you only need a single filter, something like the half-rack Symetrix 201 would be ideal. It even has a low-level pre-amp input that would be suitable for a guitar or bass to plug straight into.

    As JRA mentioned, you get what you pay for with an equalizer. I’d avoid cheap brands alike Pyle, DOD, Behringer, et.al. Background noise is an issue with cheap equalizers, and it’s especially critical for you, as you’ll be feeding it a low-level signal from your bass. That will probably have to be boosted at the mixing console, and an increase in the equalizer’s noise will come with the boost. So you have to start with a quiet EQ, not a noisy one.

    The million dollar question though, is this problem happening anywhere in the room, or just where you’re standing on stage? If the former, the EQ will make a difference. If the latter, the EQ will fix the problem for you, but will also make that note disappear anywhere else in the room. You’ll have to decide if that’s a worthwhile tradeoff or not.

    Alternately – is this happening in the house PA, or with an on-stage amp you’re using? If a stage amp, the EQ can still help, but you also might try relocating it (and/or yourself) to a different place on the stage.

    Regards,
    Wayne A. Pflughaupt

    Ecclesia: Unique Arrangements of Hymns, P&W Standards, and Original Tunes
    Administrator, Pedulla Club #45
    Administrator, Tobias Club #133
    Fretless Club #943
    Big Cabs Club #23
    My Rig: Stage and FOH Friendly
    My Basses


     
    old-fashioned and trowaclown like this.
  11. saabfender

    saabfender Inactive

    Jan 10, 2018
    Indianapolis
    Just because you stand in a different spot a few feet over doesn’t mean it’s going away. The wavelength of that F is 7.8m. If you turn down the amplitude of the peaking frequency to “normal” levels, that note will practically disappear in a sizable percentage of the room. That’s not solving the problem.

    C4E15D99-C44E-4F72-A5A9-F0C400FB6018.gif
    I wouldn’t normally make such a big deal about this but this guy is a pub musician who doesn’t have a few hundred to blow on hardware that won’t fix it.
     
    Colin Maddocks likes this.

  12. The OP should be able to pick up a decent used PEQ for under $200. If it doesn’t accomplish what he needs, it’ll be easy enough to re-sell it and not be out anything except a little time and trouble. I’ve already mentioned the possibility of “killing” the note everywhere else in the room except for where he’s standing. If that happens, it’s up to him to determine if the trade-off is worth it or not.

    Regards,
    Wayne A. Pflughaupt

    Ecclesia: Unique Arrangements of Hymns, P&W Standards, and Original Tunes
    Administrator, Pedulla Club #45
    Administrator, Tobias Club #133
    Fretless Club #943
    Big Cabs Club #23
    My Rig: Stage and FOH Friendly
    My Basses


     
    Colin Maddocks likes this.
  13. tfer

    tfer

    Jan 1, 2014
    My Zoom A3 has a very effective notch filter.

    Play the note, wait for it to start feeding back, and activate the feedback filter. It automatically senses the frequency and filters it.

    I have a hall where the G note booms like that - tames it well.
     
    Colin Maddocks and Wasnex like this.
  14. Wasnex

    Wasnex

    Dec 25, 2011
    If the problem is feedback between the instrument and PA, a device like the Fishman can help. Sometimes switching the polarity can help and the notch filter in the Fishman achieves the same thing as notching the frequency out with a parametric using a 12db cut and a Q of 8.

    A limitation of the Fishman is you only get one notch and the filter only goes down to 45 hz. So if the feedback is on the fundamental of your low F, the device won't address the problem. In my experience ABGs usually feedback at 80 hz or higher. I have an ABG with a built Fishman Preamp, and the notch filter is very useful and easy to set. If you don't want to spend much, you can pick up one of the old analog Fishman Platinum Pros for under $100. There are several available on Reverb Fishman Pro EQ Platinum 5-Band EQ

    A parametric is a better option because it would allow you to tune out multiple feedback modes instead of just one. Unfortunately parametrics are generally line level devices so they are not ideal for connecting inline with an instrument level source. They don't generally provide proper impedance or enough gain and you don't want to hit a parametric with phantom power from a mixing board.

    Although not as accurate or effective as a parametric, a graphic can still still be extremely useful for tuning out feedback modes. I used a 31 band EQ to even out the response of an amplified string bass for several years. The EQ was placed in the effects loop of an SWR Redhead.

    The advantage of a 31 band graphic EQ is they are easy to understand and use. Pro audio techs frequently prefer graphics to parametrics because you only need to push one or to faders to eliminate feedback rather than having to fiddle with three controls: 1) gain, 2) frequency, 3) Q or bandwidth. A skilled audio tech who hears feedback will immediately cut a few bands of the graphic with one hand and be done in a matter of seconds.
     
    Colin Maddocks likes this.
  15. Adienn7

    Adienn7

    Jan 26, 2007
    notch filter.. limiter.. feedback freq notching.. honestly it's not what you put in to the amp it's what you take away.. if you can loop the playing F note. then play with eq-ing in the venue. that might help. start with all bands normal. slow subtract. left to right. do the same for the limiter.
    narrowing the bandwidth can be the best thing for the situation..
    you my check out aura acoustic.. processor.. it has resonance filters.
     
    Colin Maddocks likes this.
  16. Do you have a soundhole plug? It may be all the difference required.
     
  17. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018

    Thanks
    Thanks Saabfender.
     
    saabfender likes this.
  18. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    Thanks for the advice. I do have a sound hole plus, as it was one of the first things I tried. :)
     
  19. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    Thanks Downunderwonder, I do. Cheers though.
     
  20. Colin Maddocks

    Colin Maddocks

    Feb 25, 2018
    Thanks JRA.
     
    JRA likes this.
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