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SVT CL bias

Discussion in 'Amps and Cabs [BG]' started by Brian McElwain, Oct 10, 2018.


  1. Brian McElwain

    Brian McElwain

    Aug 12, 2018
    I bought an Ampeg SVT CL! I followed the instructions and let it warm up first. Then I adjusted the bias controls. The green LEDs are on when I'm not playing. When I play the greens stay lit and the reds flicker on a bit. Is that normal?

    I've noticed that the grill cloth on the bottom front of the amp is kind of loose. Is that Normal?

    Not long after I bought it I noticed the screws on the bottom side were loose. I tightened them up. I'm wondering if maybe it was a returned amp? It was about $150 less than retail on Amazon Prime. It was an Amazon Choice item.

    None the less I'm having fun exploring the mysteries of the Ampeg SVT CL. I kind of like the new amp smell and the tones I'm getting. If anyone has info on the bias or the grill cloth on the face I would appreciate hearing about it!
     
  2. Wasnex

    Wasnex

    Dec 25, 2011

    Congrats on the new amp. It's normal for the bias lights to flicker when you play. Be careful tightening the screws as it is easy to strip them out.
     
    JimmyM likes this.
  3. Unclejackrock

    Unclejackrock Supporting Member

    Jul 13, 2006

    Red lights flickering while playing is totally normal. Mine does it too. The very first gig I played with my SVT, I noticed that the bolts on the bottom were loose too. I'd advise everyone that buys a new one to tighten them up.
     
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    When biasing the amp, turn it on, take it out of standby, let warm up in playing mode for AT LEAST 20 minutes. Playing through the amp will warm it up faster. You want it to reach a thermal steady state where the components are no longer drifting with temperature.

    Set the tone controls at noon, set the frequency knob at the center position. Do not plug in your instrument. This sets the amp up in a consistent way.

    Set the bias as per the manual. Set the pot below the set point, turn up clockwise to the bias setting. If you overshoot the position, turn counterclockwise below and turn clockwise up.

    When you are playing, don’t worry about the LED’s. However they flash at this point is of no concern.
     
  5. Brian McElwain

    Brian McElwain

    Aug 12, 2018
    Thanks, I was worried that maybe there was a problem. I'm in between bands at the moment, so I'll have to settle for playing it in the garage. I took it to a practice session for a new band and got some help putting it on top of the cabinets. I got compliments on the tone!

    Good to know that the loose bolts on the bottom are a common problem for brand new SVT CLs. Still wondering about the grill cloth on the bottom face. Is that stuck on with Velcro or something?
     
  6. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The front panel is attached with a strong velcro material. You can’t just pull it off because the fan is attached to it via a cable at the back of the chassis. It has to be unplugged first.

    This document explains it. Be very careful with what you touch inside the amp. Even when the amp is unplugged there are potentially lethal voltages.

    https://www.talkbass.com/attachments/ampeg-svt-cl-disassembly-pdf.2938853/
     
    Last edited: Oct 11, 2018
  7. Unclejackrock

    Unclejackrock Supporting Member

    Jul 13, 2006

    And I LOVE the new amp smell every time I turn it on too!!
     

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