Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Sansamp QSC question

Discussion in 'Amps and Cabs [BG]' started by aaron f., Aug 9, 2002.


  1. aaron f.

    aaron f.

    Oct 21, 2000
    Manitoba
    I'm thinking of running a sansamp BDI into a QSC rmx850, will the pedal version of the sansamp have enough power for the qsc?
     
  2. jerry

    jerry Doesn't know BDO Gold Supporting Member

    Dec 13, 1999
    Hawaii
    I had my preamp die on a gig, and I finished the gig with my Sansamp into my QSC 2402......I got through the gig, but the Sansamp dosen't really have the juice to push the QSC!
     
  3. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    According to Lloyd Schwartz at Tech21, the SansAmp can be modded so that its XLR output can put out up to +4 dBu, which is enough to drive a PLX 2402 to full power.

    Here's what he wrote to me:

    When you remove the back cover of the Bass Driver, you'll see a "black box".
    Just to
    the right of its lower right corner, there's a resistor surrounded by two
    arrows.
    It looks like this:

    >O< (except it's square)

    Remove it, and you're done!


    BTW, the resistor is an SMT type (a small black rectangular shape].
     
  4. aaron f.

    aaron f.

    Oct 21, 2000
    Manitoba
    If I remove the resistor will the only effect be a larger signal output, any change in tone or volume etc...? Can I risk damaging anything by running the modified sansamp into a mixer? Just curious. Is there any soldering involved or is it a simple snip job? Thanks for the tip
     
  5. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Well, a larger signal is a boost in volume. I don't know for sure if it'll affect tone, but probably not.

    If the mixer can take line-level inputs, you shouldn't have any problems, as long as you or the sound person adjust the mixer's input gain properly.

    I haven't seen the resistor myself, but assuming you don't have special SMT sodlering and desoldering equipment, the best way to remove an SMT resistor is with two hot soldering irons. Grab the resistor at both ends with the soldering irons and hold it for a couple seconds while the solder melts, then lift the resistor off the board. Make sure you don't make a short circuit on the board by smearing the solder; if you do, touch it up with a soldering iron, and use some desoldering braid to absorb the excess if necessary.
     
  6. aaron f.

    aaron f.

    Oct 21, 2000
    Manitoba
    One more question, if I pull the resistor out, should there be a solder connection where the resistor was or should there be a gap (no current)?
     
  7. aaron f.

    aaron f.

    Oct 21, 2000
    Manitoba
    Is there a way to boost the signal by adding some harware after the Sansamp?
     
  8. Ian Hall

    Ian Hall

    May 31, 2002
    Rialto,CA
    I just bought the sansamp RBI and a PLX1602, and had lord valve do an input mod on the amplifier, and left the RBI alone. According to him after the sensitivity mod the amp will be sensitive enough on its input to run to full power. That way, I can use the 1/4" out on the RBI at 0db into my amp, and still have the -10db XLR for going into the board at gigs. The other plus of the QSC mod is that if lord valve performs it, the amp is still under warranty, and so is the sansamp. A win-win situation.
     
  9. Ian Hall

    Ian Hall

    May 31, 2002
    Rialto,CA
    Oh yeah, and I talked to a guy at tech21, and he said the rack and pedal version have identical output voltages. Just FYI.
     
  10. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    Say Bob, I have an older Sans Amp BDI that I have wanted to use as a pre for a long time. Finally an answer....that doesn't apply to me! Mine doesn't have smt components. And none of the markings you mentioned. Could you post a link to this guy or do you know if this can apply to the older ones?
     
  11. aaron f.

    aaron f.

    Oct 21, 2000
    Manitoba
    hey inwbcstm, if I get the power amp modded to accept the lower output of the Sansamp, would it work with other preamps later. I'm thinking of popping in an Aguilar or Eden preamp in a year or so, would the power amp have to be reset or moded again to accept a stronger load?
     
  12. Ian Hall

    Ian Hall

    May 31, 2002
    Rialto,CA
    I also asked lord valve about that, and got the impression that the mod is easily reversible, if the preamp you upgraded too was too hot for the amp's input. I had also suggested to him that I may eventually want to upgrade to more expensive preamp as well. If you know the exact model of preamp that you are planning on using, you should be able to find out the output specs. A quick phone call to lord valve and he should be able to tell you whether it will work or not. The website has his phone number on it: www.lordvalve.com
     
  13. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    I would be interested in the answer too.
    I think some people use rackmount compressors for this purpose. Other suggestions?

    Matthias
     
  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I've never looked inside a SansAmp product of any type, so I can't tell you; I'm just passing the info along. Their Web site is http://www.tech21nyc.com/; you should be able to find a phone number there and get the full, real scoop from Lloyd or someone else at Tech21.

    If you're considering having your power amp (of any brand) modified to have higher gain, I just want to offer this caution: if you think you might want to resell the amp sometime, modifying it might make the amp attractive primarily to others who have low-output preamps and unattractive to everyone else--such as people looking for a PA amp.

    I'm not saying don't have your amp modified. I'm saying if you can adjust your gain controls on the preamp and power amp to get the sound level you want, go with that and don't unnecessarily jump to the conclusion that you need a gain mod.