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Noob Question: On board pre/power only?

Discussion in 'Amps and Cabs [BG]' started by Billy Low, Apr 19, 2006.


  1. Billy Low

    Billy Low

    Apr 14, 2003
    Chicago
    Sandberg Guitars
    Yeah I know this may sound like a dumb question, but is it feasable/possible to run directly to a power amp if you have a decent on board pre (OBP-1)? I would think that if you run it straight to the power amp you would eliminate alot of 'colorization' issues. This would also reduce expense and amount of equipment lugged around.:confused:
     
  2. Billy Low

    Billy Low

    Apr 14, 2003
    Chicago
    Sandberg Guitars
    Anybody?!?
     
  3. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    in a nutshell, no. A head is comprised of more than a power section for a reason. Even a pre/di (ie. Sans, MXR, Sad) won't adequately boost the signal in my experience.

    If you didn't do a search or read FAQ before posting, probably a good idea to check those functions out.

    You will find tons of useful information that never crossed your mind, gain some awareness of what's out there, and realize that most questions have already been asked and answered on numerous occassions.

    Anyway, welcome to TB.
     
  4. v-12

    v-12

    Mar 3, 2005
    FL Panhandle
    depends on the amp. my rivera tbr-5 happily takes an instrument level input, but it weighs nearly 70 pounds so there is no real weight savings there....
     
  5. LiquidMidnight

    LiquidMidnight

    Dec 25, 2000
    I agree about the SansAmp. I've always been curious to try one, so a friend lent me his Bass Driver. While I dug some of the stuff it could do when placed in front of my BBE unit, I found that it didn't have enough gain to push a power amp to my liking. I guess I should say that it's not so much that it doesn't have enough gain, but rather, to get a desirable gain level, you wind up with the psuedo-tube amp sound that the unit's known for. I don't know if the rackmountable RBI is like that or not.
     
  6. paulraphael

    paulraphael

    Apr 13, 2006
    Brooklyn
    If you heard me play, you'd stop reading what I write.
    i recently tried this with a g&l l2000 into a stewart 1.2.

    it works, but the bass doesn't put out enough signal to get maximum volume out of the amp.

    i wonder about the effects of the much lower input impedance of the amp. stewart claims 20 k.ohms; my demeter pre claims a mega ohm. A 50 X difference. This might make more difference to someone who plays with brighter strings and more high end than I do, I don't know.

    I also tried using my fullton bass distortion pedal as a preamp. This worked great. Plenty of output to drive the amp all the way, with setting from clean to full fuzz. Not quite the same warmth, detail, and dynamics that I get from the demeter, but probably no one would notice in a band setting. it's like having a pocket sized svt.
     
  7. Billy Low

    Billy Low

    Apr 14, 2003
    Chicago
    Sandberg Guitars
    Thanks, but as I tried to get that question answered by checking FAQ I could not find anything that answered this question directly.

    Oh yeah thanks for welcoming me! that's the first time in three years anyone has done so!

    ps. I origianally joined in 2002, but I forgot my user name! (don't ask):D
     
  8. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Brooklyn, NY
    I've been recently doing what you're talking about, although I have an Audere 4 band onboard pre which helps for adjustments. You absolutely can do what you're saying, you just need something to boost your gain. Find yourself a Symour Duncun "pickup booster" pedal and you're done. Bass NW has one for $49 right now. Check it out. http://www.bassnw.com/usedamps.htm
     
  9. bino

    bino

    Jun 27, 2002
    Orange County
    I was able to do this just fine with an 18 volt OBP-1 into a Thunderfunk. Did not work in passive mode. I suppose it all comes down to the amp and how much juices it needs coming out of a preamp.

    BTW, I though it sounded great. EQ'ing was obviously limited and likely not useable for live settings with only 2 bands, but I somewhat preferred it to the TF preamp.
     
  10. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Would like to claim that was a joke but I was just going by the NOOB. Didn't even look at the join date. And NOOB's are the least likely read FAQ or search cuase they haven't seen the same stuff over and over. And the search definetly has limitations beyond hitting the right keyword. Anyway, so much for assumptions.

    Anyway, the point about the pedal is a good one. You can get something fairly cheap that will drive a power amp that you can run whatever through if nothing else, ideally something you can vary the amount of coloration.. I use an Art MP all the time it was $30 shipped used.

    The technical jargon I'm not up on. Impedance and inputs and outputs - I just want something that puts out, know what a mean. Within limitations, I've looked into it enough to get me through during the rare occassions when it's come up for me.

    Anyway, I'm guessing it would vary depending on the units but for my QSC 15 or 20dB of boost doesn't cut it. Seems the Art is 48dB on one setting and that does it. Sounds like a ton so I guess it should.

    With all the technical junkies we've got, I'm surprised nobody's jumped in with that spin. Fact is, that I can't say I've run across in TB posts. I've seen a number of references about practical experience with particular gear but not the nuts and bolts explanations that typically show up - and ofter stir the ................."spirited debates."
     
  11. To drive the input of a power amp, you mainly need just a hot enough signal. The newer SansAmp BDDI and three channel model have that capability, according to what I've read on the board. And some of the 18 VDC basses ought to be able to do it too.
     
  12. Maverick Blues

    Maverick Blues Being a Thumper is all about ATTITUDE!

    Apr 28, 2005
    Richmond, VA
    I'd bet a beer you could do it with an Acoustic Image Focus SA. :)

    'rick
     
  13. pogipoints

    pogipoints Custom User Title Holder

    Dec 5, 2005
    Atlanta
    I was just playing with this a few days ago. I have an Ampeg SVP-Pro plugged into a Carvin FET150 power amp. I set the SVP to my normal levels (gain at 12:00,pad on, master at 1:30-2:00) and control the overall volume via the power amp attenuators/knobs.

    I then took out the SVP from the power amp, and plugged my bass (active, w/ bart pre) straight into the power amp input, and it actually sounded louder. So now my practice rig doesn't have a preamp anymore, just bass > power amp > cab.

    So, IME depending on its input sensitivity, it is possible to drive a power amp directly with an onboard preamp.
     
  14. Billy Low

    Billy Low

    Apr 14, 2003
    Chicago
    Sandberg Guitars
    Well I guess I don't feel as bad knowing that others have tried this already!

    It just seemed to me that if you have a pre that you dial in, and then adjust for additional eq on the head that you would actually begin to attenuate the signal due to the over equallization. I have heard of players adjusting the pre and leaving the eq on the head flat...but would that not bethe same as using the head just for power???

    I now understand that input sensitivty/impedence makes a difference.
    I should have thought of that after all of the 8 years I spent as an eletronic technician!:rolleyes:
     
  15. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    the pre still will color the tone and the bass controls are going to essentially vary eq.

    I did just get a pair of EMG DC40's from a fellow Tb'r and they kept distorting through the outboard pre's so I thought about this post and ran them straight out the jacks and stereo into the QSC since they seem to be overwhelming the pre's. Was considerably louder than most pups for sure (probably about what the Sans and other pre's were, maybe a little louder). Not like a rack pre/or the Art MP. There's respectable volume if you crank it up but significantly less nonetheless.

    So you probably could pull if off in circumstances depending.

    Pups still distorted, plan B.
     

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