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Power amp clipping and barely loud enough.

Discussion in 'Amps [BG]' started by M Sterling, Jan 29, 2013.


  1. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    Hello! I am new to the preamp>power amp rig and I have a question regarding clipping.

    I am running an Aguilar db659 into a crown xls602d into a LDS 121261. The cab is rated at around 1100 watts and features 2 delta lf eminence 12's.

    I set the input on the Pre to avoid distortion from input clipping and then set the power amp gain to about 3/4 up. Now when I set the master on the Pre to the volume I need for playing live, it makes the clip light flash occasionally on the power amp. Is this because my speakers maybe are not efficient enough to get that loud with the power I have on tap, or is there an issue with one of the other components.

    Speaker wise, I have considered swapping the 12's for some deltalite 3012lf's. Would the extra sensitivity help, or do I just need a more powerful amp. I don't usually need a ton of stage volume, but I like to have it available for many reasons.

    Thanks in advance for any help you can offer a perpetual amp noob!
     
  2. Tractorr

    Tractorr Supporting Member

    Aug 23, 2011
    Philadelphia
    Does it sound good?

    If so the clip light might not matter if it is just flashing occasionally.
     
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  4. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    It does sound fine, as I am not hearing any stress from the speakers. My concern is overheating the voice coils in my drivers due to clipping. I am no stranger to blown speakers and am not trying to go down that route again.
     
  5. temmrich

    temmrich

    Jan 29, 2012
    Dayton, Ohio
    You can try to use a compressor to limit those peaks that are causing the power amp to clip. You also might need more speakers, not more sensitive ones. If you are having trouble hitting the volume you want, it's probably not from lack of power, but rather, lack of surface area of speaker. Also, the frequencies you are amplifying (ie highs, lows, mids) might make a difference. Lots of lows can make the amp clip. You can try cutting the bass a bit and adding some low mids. The mids will give the appearance of more volume because they cut a little more, and you may be able to boost the overall volume a bit more because you cut the bass.
    Just a few suggestions.
     
  6. john m

    john m Supporting Member

    Jan 15, 2006
    +1

    If you need to be louder, ad an identical cab.

    You'll add +3dB and it will "feel" better.
     
  7. wcriley

    wcriley

    Apr 5, 2010
    Western PA
    Disclosures:
    Uncompensated endorsing user: fEARful
    Is the clipping audible?
    Most "clip lights" (the ones I'm familar with, at least) are set to come on 6 or more decibels before clipping actually occurs.
    If they're just blinking occasionally on the attack phase of notes, I doubt you're really clipping anything.
     
  8. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    Thanks, guys!

    I am running a comp before the Pre, but it is not one that specializes in peak limiting. I may look into a rack limiter to go between the Pre and power amp.

    I usually run my eq relatively flat with a little mid bump. The clipping did not increase a lot when I engaged the deep switch on the Pre or boosted the bass eq. I am generally pretty conservative with my low end eq for speaker preservation purposes.

    I do run 2 cabs sometimes, but they are not identical. I compensate for this by running them each in their own channel because of the ohms mismatch. When I do this, volume/cliiping is not a concern. I was wondering if there is a solution without adding another cab.
     
  9. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    No, the clipping is not audible and the light only flashes at the attack of my hardest plucked notes.

    This eases my mind, but I am still super paranoid about clipping damaging my voice coils.

    Thanks again everyone.
     
  10. devilman666

    devilman666

    Apr 23, 2011
    manchester nh
    You really should set pre gain master gain then control you volume with the antenuator on the power amp .
     
  11. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    Right, I have done it both ways and it usually ends up being a balancing act. The master volume on the pre does not control the di level out, so I do have some freedom there without giving the foh headaches from changing levels.

    How does this method avoid clipping more than the other? Thanks!
     
  12. wcriley

    wcriley

    Apr 5, 2010
    Western PA
    Disclosures:
    Uncompensated endorsing user: fEARful
    Even if the attack phase of the notes is actually clipping the amp, it only only lasts a few miliseconds. So I doubt there'd be much danger of damaging the voice coils unless it happens with every note.
     
  13. nysbob

    nysbob

    Sep 14, 2003
    Cincinnati OH
    Dime the power amp. Crowns are made to run wide open.
     
  14. john m

    john m Supporting Member

    Jan 15, 2006
    Most of the time. However, if you can't drive the input side enough without being too loud, it becomes a balancing act between input gain and output volume.
     
  15. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    This is what my sound man told me, too. He has never run a power amp in a bass rig, though, so I wanted to see what the TB community thought.

    Thanks again for all of the help!
     
  16. CL400Peavey

    CL400Peavey Supporting Member

    Nov 7, 2011
    Grand Rapids Michigan
    If your DI is independent of your pre's volume knob, dime he amp.
     
  17. B-string

    B-string Gold Supporting Member

    Sound like you need fdeck's HPF in the signal chain. A real speaker saver. Sounds like very low frequency string attack (pulse when you first start to pluck a string) is setting off the clip light.
     
  18. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    Groom Lake, NV
    Disclosures:
    Independent Contractor to Bass San Diego
    The power amp can reach full power whether the input gain is maxed or not. It just takes a higher input voltage to drive it to max when it's set lower.

    Anyway, OP, are you running the amp bridged? If the clip light comes on only once in a while on the hardest attacks, there's no problem, especially if you're not hearing any distortion in the cab.
     
  19. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    It is.

    I have been considering one of these for a while. The thing is though, the clipping usually happens when I dig in hard on the g string (i.e. popped notes). Obviously it clips in the lower register too, but I rarely pluck very hard down there anyway.
     
  20. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion Gold Supporting Member

    Aug 25, 2010
    The Great Midwest
    I would also invest in a Microthumpinator
     
  21. M Sterling

    M Sterling Gold Supporting Member

    Sep 23, 2010
    Pittsburgh, PA
    No, I'm running each side independently. I'm not sure if my power amp will do 4 ohms bridged.

    There is no distortion from the cab, it actually starts to sound very good once it's pushed pretty hard. I burned out the voice coil in a deltalite 2512 loaded aguilar gs112 with this power amp, so I'm super worried about this. Fortunately, the LDS seems be able to handle the power with ease.

    Thanks for the response, I'm starting to feel better about the situation.
     



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