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SVT Classic 80hz bump?

Discussion in 'Amps and Cabs [BG]' started by jallen97, Mar 19, 2014.

  1. jallen97


    Nov 12, 2007
    So, I'm trying to help a friend with his rig. I noticed the other day when he played an E on his A string(at the 7th fret) it was quite a bit louder than any other notes. So I started thinking that note would be around 80hz. I mistakenly thought his amp had a graphic EQ and that we could just pull back 80hz. It doesn't, that's a dif model. He also has a sansamp bass driver. Neither the amp or bass driver have a sweep for this frequency. I haven't actually tried to make any adjustments on his rig, but am trying to do some research to figure out what to try. The amp does have a sweepable mid that has a notch at 220hz.
    I was just wondering if anyone has dealt with this kind of issue. Oh yeah, he plays a passive P bass and I'm pretty sure it's a 410 ampeg cab. And there is a hollow stage that the amp points right at. I do wonder if it may be the room or maybe the combination of the room and the ampeg...
  2. blr2


    Apr 21, 2010
    Sofia, EU
    Looks to me there is a room resonant mode around 80 Hz. In other words, it is connected to the room and not the amp. Try the setup in a different room or at least try to move the cabinet around the room.
  3. Grissle


    May 17, 2009
    I've had the same issue a few times, depends on the room, but its always been in the same range. Using Ampeg heads and an 810e cabs. Two of my heads have graphic EQ's or I use the one in my Bass PodXT.
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Try a different EQ. Try another bass in the amp and see what it does.

    It is possible that the issue is the bass. It has to be tested in another room or with another amp. If it is the instrument, a pickup height adjustment or different strings could help. IT might just be a quirk of the instrument. It could be a resonance in a pickup. Sometimes in these cases, sealing the back of the pickup with wax can help.

    Rule that out, then look for an issue with the room. Trying the amp in another room may help.
  5. StuartV

    StuartV Finally figuring out what I really like Supporting Member

    Jul 27, 2006
    Manassas, VA
    I've seen so many posts on there that say "you don't really hear the fundamental on the low notes. You hear harmonics" that it makes me wonder if, even though the fundamental is around 84 Hz, maybe the resonance is actually happening at a higher frequency.

    Of course, this would be simple enough to test - if nothing else, by setting the mid switch to 220 Hz and turning the mid knob down to see if it helps or not.
  6. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    This is the very first thing I'd try. Ambient acoustics can cause dramatic effects no matter what gear you use.