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Active Pickups : Serious Help Needed

Discussion in 'Basses [BG]' started by Sanctum, May 15, 2002.

  1. Ok I'm at my wits end. The story ->

    My Fender active 5 string (18v) has been causing pretty bad clipping with my SVTIIIPro. Its to the point now where I cant even get any good volume from the rig. At first I just figured it was my rig not handling the load. Here's that setup:

    SVTIIIPro into an Ampeg 4x10 (500 watts, 8 ohm) and an Ampeg 1x18 (175 watts, 8 ohm). The head is running the full 450 watts at 4ohms.

    I just figured the head was clipping from the speaker wattage. Tonight I plugged in my guitar players Ibanez passive 5-string, and was able to get some pretty good volume from the rig, although it did still clip if I pushed the gain up.

    So my main question now is, could my Fender be putting out some weird voltage or something? I havent owned an active bass in years, so I'm a bit pissed off if this is normal - do I need a new more powerful head? Is there always this kind of differential between active and passive? Am I insane? I soon shall be if I cant work this out, I dropped a bit of cash on the FMT :mad:

    Ok, and yes, I DO know how to use the -15db switch on the amp, heh.

    Sorry to put this in "basses" when I'm going on about the rig, but my concern is for being able to utilize this bass as I feel I should.


  2. i forgot to ask for some technical info regarding active pickups and the preamp in the signal chain. What that relationship is to clipping and cab wattage load on any particular head.

  3. jasonbraatz


    Oct 18, 2000
    Oakland, CA
    if you put 1000W into a 100w cab, the sound you'll hear is more "farting out" than clipping. you should be fine - underpowering cabs will just make you not be able to turn up as loud as you could with a head of the right wattage.

    if you're hearing clipping, it's somewhere in your head or the bass. maybe there's a trim pot inside the cavity that's up too high? maybe your battery is dead?

    active's put out more power than passives, but not that much more.
  4. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Sounds like your bass's output is too high. I don't know whether the new 18-volt Fenders have an output gain adjustment, but the easiest way to deal with it is turn your bass's volume pot down and turn your amp's preamp gain up.
  5. Batteries are fresh, 5 days old.

    I dont see that the pots are adjustable in the rear cavity.

    Lame ;-(

  6. Does anyone think the above head/cab config is out of whack? Cause on the surface I dont think its power config is out of the realm of reality. Despite my previous defences of the head, I'm starting to hate the SVTIII Pro. But as this is the bass forum, I wont go back into that.

  7. Philbiker

    Philbiker Pat's the best!

    Dec 28, 2000
    Northern Virginia, USA
    It really sounds like you're overloading your input on the preamp part of your rig.
    And it doesn't help, huh? The only thing I can think is to turn the volume down on the bass or change the trim. That would be a tiny adjustment in the electronics inside the bass.

    You should have your power amp cranked all the way up and are using the preamp gain to adjust volume.
  8. Planet Boulder

    Planet Boulder Hey, this is a private residence...man

    Nov 10, 2001
    6,482 feet above sea level
    I once had impure thoughts. Oh, and I pluck my ear hair.
    Though I don't turn it all the way up (my volume settings between gain and master are blended more evenly), I generally agree with this statement.

    I was having the same problems with my Carvin R600 head, even with my passive P-Bass, until I started dinkin' around with the gain on the head's preamp. Further, I turned the bass' onboard volume down and relied more on the the amp master volume than on the gain from the preamp and from the onboard volume.

    Basically, it's going to take a lot of fiddlin', but you will get the issue resolved. I don't have too many clipping problems now, though I still have some, thanks to a head I don't particularly care for.
  9. well i've tried that too. with the volume cranked the cabs get distorted sounding, and then i cant even get the gain past like 7 or 8 oclock.

    good news is i just ran to the music store and played my bass through an Eden rig - 300 watt head and a 2x10, it was louder than my whole ampeg rig, hahahah.

    i'm getting ready to toss the svtIIIpro in a swollen, flooded midwest river and start over.

  10. Ok, well I just took the SVTIIIPro to the store and ran it through an Eden 410T. ****ing kicked my ass. So nothing wrong with the head either (gotta get it out of the river, hehe). Plenty of power, volume, tone, no clipping even with the gain fairly high. And that was with one 8ohm cab.

    So I'm down to cabs now. In case anyone cares, I'll post a follow up, and this can probably move to Amps now, since the bass problem is nil.

  11. Brad Johnson

    Brad Johnson Supporting Member

    Mar 8, 2000
    Gaithersburg, Md
    DR Strings
    There's really no need for a gain pot on the Fender 18V, there's no passive mode so there's nothing to match. That's not lame, it just is.

    The quickest way to get to the bottom of this is with a logical approach, understanding how one this does or does not affetc another and going to the next logical step.

    With the real obvious stuff rules out (weak battery, strings too close to pickups, etc.), here's where I'd look:

    You ruled out the bass when you used the Ibanez and got clipping. You should be able to run the volume control on your bass wide open, period.

    If it were really overloading the preamp it should clip with the Pre gain up, even with the Master volume down low. Doesn't sound like that was happening.

    You have two cabs, did it sound like crap with each when tried alone? I'm betting the answer is no.
  12. ok, i brought the entire rig home, plugged in each cab seperately, sounds fine, both hooked up, sounds fine, plenty of volume, tone, no clipping ... hmmmmmm

    then i remembered that the electrical outlet i plug into where we rehearse went out about a month ago. Guitar player had it "rewired" by "someone", heh, sooooooo, now I'm thinking this might be the problem. Could it be? Wired backwards or spiking or something?

    This has become all too weird and quite a chore. Damn, and I thought the Eden GAS would solve my dilemma :)

  13. bump
  14. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    try a power tube swap. most times its cause somthin's up in there. my stewart is really sensitive to what my preamp pumps into it. so i'm always having to turn the internal trim down.
  15. embellisher

    embellisher Holy Ghost filled Bass Player Supporting Member

    Dubious wiring is likely to be the candidate. I beleive that if the outlet is putting out too low of a voltage it will cause problems like this.
  16. wonder what else is on that circute U plug into. Could be as simple as a microwave being run on the same line.

    All this heartache over a frozen Buritto :D
  17. ROFL, too true


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