Gallien Krueger 400rb vs Ampeg Cabs

Discussion in 'Amps and Cabs [BG]' started by JazzneckP, Jul 8, 2013.

  1. JazzneckP


    Jul 8, 2013
    Auburn, AL
    I picked up a used GK 400rb (late 80s vintage) a couple of weeks ago. At first it had some issues cutting out and distorting, but I discovered there was a broken solder joint on one of the treble pot. I repaired the solder joint and have been experimenting with the head.

    I have three cabs: Ampeg SVT 15E (8 ohms), Ampeg SVT 410HEN (8 ohms), and AMPEG SVT 410 HLN (4 ohms). I've been experimenting with this head and each of the cabs individually. I love the high end pop. My Ampeg SVP & power amp rack can't match those highs. However the lows are puzzling me. If I have the Master Volume set on 10 (5 o'clock), I cannot turn the Volume up past 5 (12 o'clock) without getting serious distortion from notes on the E string. This goes for all the cabs. I figured the HLN would be able to handle just about anything @ 1000W and 4 ohms. Note the HLN has 4 brand new Eminence drivers.

    It works best if I put compression between the bass and the head. I know that's squashing some of the low end. I'm also rolling the bass back on the head to about 5 (12 o'clock).

    I can return this head if there appears to be something wrong with it. I just wanted to see if pushing the Volume, Master Volume, and Boost pots up (past 12 o'clock) on the 400rb causes the output to distort, or could this be a defective unit.

    Note I am using a Music Man Stingray 4 and a Sterling Ray34 for testing. I have checked the cable and have high quality speaker cables.

    Any thoughts?


  2. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    The GK has a lot of power in the eq. Roll the lows back, bump the mids.
  3. dave_p


    Dec 20, 2005
    Set everything at noon to start, boost at 10. You should be pleased. If not jump the effects loop, it could be dirty.
  4. The 400RB is NOT known for lacking in lows (unless you press in the low cut switch). You may indeed have other trouble with the amp if you need to turn the master and input volume that high. They are usually VERY loud for a 200 watt amp. Note most all amps will not stay clean with all controls dimed.
  5. JazzneckP


    Jul 8, 2013
    Auburn, AL
    B-string - makes sense. I was trying to compare the output to my other amps. The 400rb is pretty powerful for 200W. I was pegging the Master at 10 and working my way backward to get the tone. In comparison to my Ampeg gear, the first Volume is kind of like the Gain, the Boost is the Drive and the Master is the same. Without a clip light it's hard to tell when you get the gain too high except by ear.

    I guess I figured the head could drive my cabs harder, but there is a balance among the active bass gain and the Volume, Boost, and Master pots. In other words, you can't turn them all up to 11!

  6. majortoby


    Jul 2, 2009
    Tampa, Fl USA
    Were these exact OEM replacements for the original speakers?
  7. Exactly and with a single 8 ohm cab it is about 140 watts, the single 4 ohm cab will be 200. :)
  8. dannylectro

    dannylectro Supporting Member

    Aug 2, 2010
    Hartsdale, NY
    I own 3 400RBs and play through an Ampeg 410 at 4 ohms with both active and passive basses. What is happening with your head is not normal; something is clearly dirty or broken.
  9. JazzneckP


    Jul 8, 2013
    Auburn, AL
    majortoby - yes, the speakers are exact replacements for the originals. Cab sounds fine with my Ampeg preamp/poweramp setup.
  10. JazzneckP


    Jul 8, 2013
    Auburn, AL
    dannylectro - do you run your 400rbs pegged out on the Volume, Boost, and Master?
  11. dannylectro

    dannylectro Supporting Member

    Aug 2, 2010
    Hartsdale, NY
    No... I literally run it with every knob at 12 o'clock, and the filter buttons out (not used). Depending on the venue, I may slightly goose or reduce the bass or lo mids, and for some tunes needing a little more clank I'll engage the Hi Boost.

    I never have a problem getting deep, rich bass, and I never get distortion at all. In my opinion & experience, old style transistor amps like the GK don't really like being pushed to create distortion - they don't perform like tubes. When I need some ugly, I use a Tech 21 VT Bass.
  12. Dave W

    Dave W

    Mar 1, 2007
    Westchester, NY
    Is that what you're doing?

    Cranking the master all the way up and playing at a loudish volume is going to give you the infamous GK growl. Adding in more boost (anything over 12:00) is going to add more.
  13. coreyw666


    Dec 22, 2008
    I just bought an 89 400rb on ebay I got it checked by a tech as well as the power chord replaced. I use it through an acoustic 410 8 ohm with the boost dimed and the high boost and mid buttons in everything else at noon. Its twice as loud as my last head and crystal clear despite looking like someone beat it with a hammer. I also woukd try the patch cable on the send return it helped mine.
  14. sunfighter


    Nov 26, 2011
    Yeah something isnt right with that head.
  15. JazzneckP


    Jul 8, 2013
    Auburn, AL
    Thanks for all the replies.

    I'm pretty sure what I am hearing is clipping. I am playing through a pretty hot bass (Stingray). If I keep the Volume knob less than 10 or 11 o'clock, that keeps the amp from clipping. My Ampeg B2 works about the same with the Gain knob.

    Again, I just wanted to put this amp through its paces and make sure it was working as expected.