gear help for technical novice!!

Discussion in 'Amps and Cabs [BG]' started by petalred, Feb 13, 2006.

  1. petalred


    Dec 6, 2004
    hey! so i'm a decent bassist, but i'm a serious novice when it comes to technical issues (i mean, i know how to hook up a head to a cab in such a way that neither of them is blown up, but the extent of my knowledge pretty much ends there). i want that to change, but for the moment i just need my rig to sound good again.

    here's what i use:

    Head: Ampeg SVT350AV (200W at 8ohms, 350W at 4ohms, solid state)
    Cab: Sunn 215 (300W at 8ohms, two 15" speakers, this is a Fender Sunn, not an original)
    Bass: Musicman S.U.B. (passive, four-string, DR Hi-Beam strings 50, 70, 90, 110, possibly about to make the switch to 65, 85, 105, 125 to accomodate for a band i'm joining that tunes to drop A)
    Pedals: Ernie Ball VPJR (volume pedal), Boss TU-2 (tuner), Boss CS-3 (compression/sustain)

    now, normally i love the way my equipment sounds. it's really mid-rangey and at the 6 o'clock position across the board (gain, volume, bass, treble, high, no eq, no limiter, no pad) i haven't met a lone guitarist yet who can compete with me for volume without putting at least one 4x12 on either side of me. recently, however, my low notes have started to fart a lot and the tone just doesn't quite sound right anymore. i feel like it's a cab issue because a) the farting, and b) the head still sounds awesome on other cabs i've tried, but both speakers still seem to be putting out sound. does anyone have any idea what the issue could be? is there some inexpensive repair work i could do to my cab, preferably on my own? i've been flirting around with the idea of picking up an acoustic cab or an ampeg svt810e for a while, should i just cut my losses and do it?


    also, while we're on the subject, would the following buttons on the back of my head have anything to do with this, and even if they don't, where should i be setting them? button a: UP=PRE, DOWN=POST, button b: UP=0db, DOWN=-20db. like i said, my technical knowledge is low, and although these buttons seem pretty intuitive, realistically i don't know where they should be set or if either of them is causing damage to my cab by being incorrectly set.

  2. petalred


    Dec 6, 2004
    oh, also, my head needs a little work. when i purchased it the fan didn't work at all, and i have a friend of mine investigating getting a new fan for me, but in addition to that some of the eq sliders have broken off and the input jack (though functionally okay) is missing the part that protrudes outside of the amp. anyone know where i could get replacement sliders, by any chance? anyone know how much it would cost me to have the sliders and input jack repaired?
  3. LarryO


    Apr 4, 2004
    sounds like you just need to add another 8 ohm cab so that you can move more air and use all 350 watts. If your 2x15 is an 8 ohm cab you're only getting 200 watts from the amp. I'd add another cab but you may want to do some research first. You need to push enough power to each speaker in order for you to get more volume without distorting. If you like the sound of a 2x15 cab, you may want to buy a 2x15 that is wired at 4ohms or 2, 1x15 cabs wired at 8 ohms each.
  4. petalred


    Dec 6, 2004
    i've definitely considered the possibility of adding another 2x15 to more efficiently use the amp, but should that really affect the problem i'm talking about? volume isn't an issue for me. as i said before, with the current setup i'm more than competitively loud, it's just that recently the low end has been crapping out a lot, and i'm wondering if that's an amp problem, or if (as i suspect) it's a cab issue, is it a blown speaker? is there a cheap way to get it fixed quickly (i leave for tour in two weeks)?
  5. LarryO


    Apr 4, 2004
    i think you're better off using a single 4 ohm cab rather than 2 8ohm cabs. The reason I say this is if you added a 2nd cab and it had 2 speakers (2x10 or 2x15), that would total 4 speakers. If both cabs are 8 ohm, youramp will push 350 watts. that means each speaker would only be getting 87 watts each. You'd loose headroom on those 15s. If you just plugged in 1, 2x15 cab or 1, 4x10 cab that is wired at 4ohms each 15 would recieve 175 watts......each 10" would get 87. I think that would work out better for you. Of course I could be wrong but If you like your amp, I'd look for a 4x10 or 2x15 4ohm cab
  6. Wesley R

    Wesley R Supporting Member

    the speakers could need re-coning.

    Best of Luck,
    Wesley R.
  7. petalred


    Dec 6, 2004
    crap. after all the research i've done today i think this could be a problem i really need to address at the cause, not just at the symptom.

    things i learned today:
    a) when i turned on my amp and saw that my fan wasn't moving, i may have made a wrong assumption that the fan actually wasn't working at all, as ampeg's site mentions with regard to my amp's closest surviving descendent that it's normal for the fan not to turn on when the amp is first powered up.
    b) when i would be playing and my amp would start cutting out, it was likely not overheating as i assumed (because i was also under the assumption that the fan wasn't working), and may well have been severely clipping. this would explain my cab suddenly sounding so much worse. i read a few of the FAQ threads and suddenly feel like i know much less about safely hooking up cabs and heads than i thought i did.

    is a head putting out 200w at 8ohms to a 300w RMS 8ohm cab, played at 50% volume trying to suck up too much power and damaging my speakers? is that what's causing the clipping? would i be safer with a much higher rated head, played at a significantly lower volume? is my plan to replace the 215 with an SVT 8x10 just going to make the problem worse? i assumed (wrongly, i now gather) that it was no problem having a cab with a drastically higher watt rating than a head, and that pulling the whole 350 watts out with a 4ohm cab that could handle 350 watts would keep me loud without risk of damaging the cab.

    is there a perfect cab and perfect volume setting for the amp i already have that will maximize efficiency and minimize risk?
  8. LarryO


    Apr 4, 2004
    do you like the tone of your amp? Do you know what cabs you like the sound of best?

    right now you are pushing 100 watts to each speaker. That can be loud depending on the speakers and your eq. But most people will say it's not loud enough. I think your amp has enough power. 350 watts is plenty, you just have to match it with the right cab and send the right amont of power to each speaker.
    I'd start with a different cab. I'd use a single 4 ohm 2x15 or 4x10. find a used cab that can handle close to or more than 350 watts (there's a big thread regarding that and I'm not getting into it) and give that a try.