Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Why does my amp peak out when it's only on 4?

Discussion in 'Amps and Cabs [BG]' started by Chris A, Feb 22, 2003.


  1. Chris A

    Chris A Chemo sucks!

    Feb 25, 2000
    Manchester NH
    Hey guys,

    I have a Peavey Tmax, and it's got enough power, but I just joined this new band and the guitar player plays LOUD!! I have my amp on 4(usually it's around 2 for other gigs), about half way through rehearsal the power amp section's red light that signals the DDT(emergency compression) starts going off when I play notes down low on the E and B strings. If I'm not even running half the volume of the power amp section why does this happen? It happens whether I have my 2x10 4 ohm cab or my 15" 8 ohm cab or both. And the amp is rated to go down to 2 ohms. Any ideas?
    There is no noticeable change in tone when the red light come on. Is it that the amp is too hot? It only happens after the amp's been on for a while.


    Thanks

    Chris A.:rolleyes: :bassist:
     
  2. Sounds to me like you have mismatched cabs. I'm not familiar with your amp, but unless you have the two cabs running out of seperated sides of your amp (like an eden) were you can run one 4ohm and one 8ohm your probably not hooked up correctly. Do you have an owners manual? If you have your cabs "daisey chained", one running off of the other you may have your problem there. Otherwise I would say you just don't have enough power or some kind of compression is on etc. I'm sure someone else can comment too. Since I got my PA style amp (qsc plx 2402) I don't have any issues like I did with the combo type heads such as the Eden I mentioned. If you don't hook those amps up right your asking for mucho headaches... hope this helps. Post your fundemental specs when you ask a questions of this nature, it will save on the back and fourth question answer emails and get you a quicker solution. Good luck my Bro.:)
     
  3. CS

    CS

    Dec 11, 1999
    UK
    I'm no techy and I only came here out of curiosity (it's a post by Chris A-they are collectable).

    I had a Hartke 1410 that had a limiter with a gren light-it would go off sometimes on half volume. THe manual said that it was ok if flickering but worth turning down if lit all the time.
     
  4. jobu3

    jobu3 Artist formerly known as Big Joe

    Feb 17, 2002
    Mountain Top, PA
    are your lows boosted too much? that could do it...
     
  5. Chris A

    Chris A Chemo sucks!

    Feb 25, 2000
    Manchester NH
    I play with a pretty flat eq. and the red light happens no matter which cab I use. Either or both.


    Chris A.:rolleyes: :bassist:
     
  6. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    If you have the power amp section turned up only half way, you're not getting enough headroom. Before you bring up your pre-amp gain, turn your main volume up all the way. Then get your overall volume at the gain knob.
     
  7. Chris A

    Chris A Chemo sucks!

    Feb 25, 2000
    Manchester NH
    I'll give that a shot this week, thanks Munji.


    Chris A.:rolleyes: :bassist:
     
  8. Stingray4Christ

    Stingray4Christ

    Jan 28, 2003
    NY
    i thought the gain and the master were supposed to be at about the same level:meh: ?
     
  9. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Yay, finally someone else who uses this method. I'm surprised more people dont. It's a great way to practically guarantee you won't ever clip your input gain. Sound guys usually shoot me down with talk about "signal to noise ratio", but that's not an issue so ignore them.
     
  10. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    I only do that when I need the headroom. Otherwise, I usually set the gain and volume about the same.
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Actually that's a good point. My current amp is a bit too powerful for this idea. It makes the gain control very touchy. I'll go to my amp looking to add bit of volume, I'll move it one poofteenth, and the volume tripples.

    The principle is good though - keep the input gain low, especially if you don't have a clip light.
     
  12. Whappo Grande

    Whappo Grande

    Feb 9, 2002
    Santa Clara, CA.
    Manager: AccuGroove Speakers
    I always use this method, whether it's a stand alone head or my preamp/amp rack. Master output is all the way on and then I dial in the input volume or gain. It’s the only way to fly.

    Whappo
     
  13. A setting of 0-10 on your master volume does NOT equal output power from 0-100%!

    If you have a strong signal feeding into the power amp (i.e. big bass boost), you'll reach max power below 10, and if you have a weak signal to begin with (i.e. cheap passive bass), you won't get max power out of the amp, even at 10.

    Sounds like you're just running out of power, meaning you need more watts.

    To cut things short: if the clip led comes on, you ran out of power.

    My view on the matter.
    Regards,
    Joris.

    BTW, I'm always setting my gain to get the hottest signal just below clipping of the preamp (this minimises noise and distortion), and turn up the master volume to as loud as I want. This is the most logical way to set up a system. Not everybody does it. Not everybody is always following logic.
     
  14. Yup. Amps are made to deal with a variety of signal levels and thus need to have adjustable gain. How high you have the volume knob to get full power depends on the output level of the bass, how hot you have your preamp, and your EQ. If the DDT LED is coming on, you're out of juice. That being said, I wouldn't worry about the DDT LED flashing a bit. You really only need to worry if you can actually hear distortion.

    You're selling yourself short in the tone department if you're not running the preamp gain fairly hot. This is the way amps are meant to be set up. I haven't come across a preamp yet that didn't sound its best with the gain a bit below clipping. You also get better S/N ratio by doing that. The odd preamp clip light on a peak isn't going to hurt anything. Lots of manufacturers suggest setting their amps up like that in their manuals. SWR is a good example.
     
  15. Chris A

    Chris A Chemo sucks!

    Feb 25, 2000
    Manchester NH
    But the preamp isn't clipping at all, I'm running the preamp around 5, and the power amp around 4. I have tried it with the different cab combinations described above, and with my active Lakland 55-01, and with my passive Kingston. I'm not a soft touch with my right hand technique, but I'm not shooting bows and arrows, either.


    Chris A.:rolleyes: :bassist:
     
  16. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    But the DDT compression is kicking in right. I've never owned an amp with DDT compression so I could be wrong, but my understanding of DDT compression is that it kicks in to prevent clipping and protect your speakers.

    Is the compression adjustable? if so might be worth fiddle.

    You said you'de give Munji's idea a try. How did it go?
     
  17. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    That's right. 600 minimum.
     
  18. That's not right :confused: It depends on a lot of factors how much power you need for your specific situation. I got by with 150 watt for years. Now I have 480 and easily get by in a loud metal band.

    But I guess you were kinda joking.
     
  19. I agree that you want more power in your rig. My last head I used to get the peak light coming on at around 3.5 on the volume, added 150 more watts and now it comes on around 5. I suppose I should have added another 300 watts in retrospect...

    Bottom line here IMO is that you need more watts for more clean power which will negate the compression from kicking in to avoid clipping. Dropping the low end EQ a tad would help too.
     
  20. Whappo Grande

    Whappo Grande

    Feb 9, 2002
    Santa Clara, CA.
    Manager: AccuGroove Speakers
    You can never have "too much" power in reserve, but you could end up with to little. It's better to error on the side of having a little more than not enough.