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Rig stage volume disappointment

Discussion in 'Amps and Cabs [BG]' started by mrpackerguy, Aug 4, 2005.

  1. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    I'm running a Sansamp RBI into a Yamaha P5000S parallel into two 4-ohm Acme Low B2 II 2x10's. In most instances I'm running through the PA.

    While I'm very happy with the quality of the sound I get from my MM Sabre active and Fretless Active jazz bass with this rig, I'm disappointed in having to crank the Yamaha amp and crank the RBI to get a decent stage volume and, volume in general.

    I thought by upgrading from a QSC RMX850 to the Yamaha, I'd have more headroom, but I'm finding the difference marginal, even though the Yamaha runs twice the power (750W/side) than the QSX RMX850 (300W/side).

    I've heard about the Acme's wanting juice, but c'mon, more than 750W? Would upgrading the amp further really solve the problem, or just put me at risk for frying the Acme's? Any other thoughts or recommendations?
  2. Lonnybass

    Lonnybass Supporting Member

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    I don't have any experience with Yamaha amps, but I do know that Acme's will take any good power amp for all its worth. Most guys on here have had good luck using high powered Crown's, Crest's, QSC and Stewart setups. For a 4 ohm B-2, you should be putting about 650 watts into it to expect "the goods."

    Other suggestions for getting more volume...

    1) Stack your B's vertically.
    2) Boost your mids at about 500 hz
    3) Roll off some of the lows

    Good luck.

  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Running nearly twice the power will get you about 2.5dB, a hardly noticeable improvement as you've found. To get a worthwhile increase you need to boost power by at least a factor of four (6dB), if your speakers will handle it, or switch to higher sensitivity speakers, again by a factor of at least 6dB/watt to make it worthwhile.
  4. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    OK - so I've never owned an d RBI but isn't that pre considered a bit weak on the output side ? Seem like I recall that in threads around here. Maybe you're not giving the Yammy enough voltage to drive it to full power ?

    You could take the output of the RBI onto a compressor and instead of compressing, use it as an additional gain stage to bring the voltage up...

    As a secondary note, does the Yamy have a sensitivity switch ? Lot's of power amps (like my Crown) do.
    If so, is it set appropritately ?

    Just a couple of things to think about / have a look at.

    or dump the Acmes and get a set of Bag Ends ...
  5. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    Thanks. No sensitivity switch on the Yammy. Good thought on the compressor idea. I'll get my Behringer hooked up and add some gain that way and see what happens.
  6. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    (well, the noise floor will come up anyway ... allright, I'm kidding...) :ninja:
  7. I have pretty much the same rig, except I use the pre from my wt-330 to drive the yammy. Go around back on the amp and set the x-over switch on each channel to low cut and set the knob at about 40 hz or so. The variable cutoff filter on that amp IMO makes it a very underrated power amp for bass applications. This gave me a lot more volume without losing much tone at all.

    Question: Are you getting the cabs to fart? If so my suggestion should do it, much more volume, no farting. If not, I blame the output level of the RBI.
  8. Let your clip lights be your guide. There is nothing inherently wrong with having to crank them up to get volume. If the RBI typically has a low output, and the yamaha requires a hotter than average signal to reach full power, it could be that you need to run the yamaha wide open for the RBI, whereas with a BBEMax or some other preamp would get the same volume with the yammy set at 50%.

    Set input gain until clip light is rarely on. Set output knob of RBI as high as you need to get output meters or output clip lights (if any) showing around full output, again, minimal red zone or clip light activity. And set the yammy wherever you need to to get the volume you want.

    The key to setting up audio gear is look at the meters/clip indicators, not the knobs. All your goals are geared toward maximizing gain without clipping at each stage.

    Watch the meters/clip lights, ignore the knobs position.

    Anyone who tells you the power amp gain control set at a certain fixed position (70%, 100%, 30%) is "optimal", or "excessive" doesn't know what they're talking about. It could be almost anywhere depending solely on the strength of the output of your particular preamp relative to the input sensitivity of your particular power amp.

    If you've got the RBI and the yamaha cranked and not getting full power out of the yammy, the RBI doesn't have hot enough signal for that power amp. Need more gain, not more power in that case.

  9. remember to use the input on the rear of the RBI, the front one is a -20dB or something IIRC

    That would be a prime suspect all right....

  11. BigMikeW

    BigMikeW Banned

    May 25, 2005
    Nashville, TN.
    Banned by TB Administration for refusal to account for funds

    YEP! That's it. RBI's have a TON of output. I use them everyday.
  12. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    Also remember that Acme cabs are very inefficient. Sound great, but inefficient.
  13. Juniorkimbrough


    Mar 22, 2005
    Mississippi / Memphis, TN
    Endorsing Artist: Lakland Basses
    fwiw, i switched to my rear output on my RBI and it really didn't increase it that much.....a little, but barely noticable. Got band practice this evening so I'm gonna go back and double check everything.
  14. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    No, I'm not. Not even close. I'm going to set the Yamaha filter as you suggest and go exclusive with the rear RBI input even though I also tried that without much success. I think that rear RBI input also has a 0dB/-20dB button if I'm not mistaken. I'll be sure 'm not at the -20dB in the rear.

    I'm also going to watch the clip lights with the RBI and Yamaha cranked.

    Thanks guys! I'll report later this evening. Now let me go home!!
  15. Just out of curiosity, the volume on your bass is turned up right ?

    :smug: never know
  16. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    Yep, got that one covered.
  17. I'm running 1800 watts into a Low B4 and honestly, it's damned loud and quite capable putting out an uncomfortably strong amount of low end and projecting it way across a room with those 4 long throw drivers. Have you tried going out into the crowd and listening to how it sounds? A lot of the sound is probably blowing right past you.

    Still, a pair of Low B2s is just getting started w/ 750W between them. Try cutting some of the low end output on your preamp or on your bass itself. I set my BBE BMax on "2" (which is the flat setting) and I usually roll the bass off a little on whichever instrument I'm using, and it's still more than enough.
  18. Hey James, I think he's going 750 to each
  19. My bad. Hmm well in that case yeah, it should be pretty loud. Once you get much over that you really can't add more power and expect to get any more volume, since you're getting into driver-frying territory the closer you get to 2000W.
  20. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    I took the great suggestions everyone gave me. Turned on the Low cut filter of the Yammy and set it to 40khz, hooked up the rack mount Behringer compressor and inched up the gain a bit on the compressor, increased the gain to max on both channels of the Yammy and the RBI, ran my bass through the rear input and set it at zero-setting DB (not -20), configured the two Low B2 cabs in a "t" formation, as my 2nd speakon cable would not allow for a vertical end on end stack.

    You want to know something odd, I still can't get the Yamaha P5000S to clip, not even with my Jazz Bass Deluxe's gain up full. I'm not sure what that tells me.

    But there's a definite increase in volume, I think sufficient enough to make me happy on stage. Next gig will tell.

    All great suggestions. Many thanks.