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Line Out Advice Needed | Newbie with little cash

Discussion in 'Live Sound [BG]' started by Ralphthepainter, Nov 8, 2019 at 11:30 AM.

  1. Hi everyone. First post.

    Need a little help. It’s easy to give advice telling others what they should buy. Money solves a lot of problems. I don’t have any. Now that I’ve shared that I need down and dirty...get by... in a pinch, kinda advice on how to make things work on the extreme cheap.

    Problem - bass guitar line out into board farts and doesn’t sound good. Need suggestions on how I can improve a bad situation.

    Gear - Fender P Bass into SWR LA15. Line Out from Amp through TRS to Mixer TRS.
    Mixer is Studiomaster diamond series 12/2 (analog). Mixer sends to EQ then Crossover using sub sum out to single Bag End 15” subwoofer. Cross over is set 150hz below to sub the rest to the mains (FOH only) Bag End 12-c speakers.

    I tried yanking out the bottom to make the farts go away. Didn’t really effect it much regardless. I don’t think the farts are because the speakers.. I think it’s something to do with the signal path. The farts are there weather it’s a 15’ TRS or a 100’ TRS. I set the gains really low at the board inputs but I really don’t think that did much to make the farts go away. I also turned the LF in the channel all the way off... while it shaped the sound.. the farts stayed consistent. It farts using the big E string open or barred. Non of the other strings make the fart, leading to my reasoning it was frequency.. but it may just be the signal strength due to my wire path?

    I’m not convinced my line out from the LA15 is balanced. The manual says use a sheilded patch cable for the line out... would a different cable be better?

    I also have a TRS transformer to XLR balance adaptor.
  2. Wasnex


    Dec 25, 2011
    If proper gain staging does not fix the problem, the line out on your amp may be damaged. Borrow another amp, preamp, or DI to run into the mixing board to see if the problem goes away.
    wintremute likes this.
  3. donk


    Nov 5, 2006
    line out level might be too hot for mixer. try line out into a DI to send a mic level to the board, see it there is an input pad on the mixer and engage it
    Paulabass likes this.
  4. SWR wasn't very good with LF noise filtering in their preamps.
  5. I tried the gain for the input on the channel and the frequencies in the channel, but nothing helped.
    I’m starting to suspect this.

    Might be.

    Here are some excerpts from my Manuel’s with the board and amp. Can’t tell for sure in the amp line out is balanced.. sure feels like it when inserting a TRS.


  6. DirtDog


    Jun 7, 2002
    The Deep North
    Yep. I'm assuming you ARE using the Line In on the mixer, not the XLR? That model mixer doesn't seem to have a gain pad, so you're stuck with the rotary preamp gain dial at the top of each channel strip.

    What happens when you try the bass on another channel on that board?

    On any of those channels, when does the clip light come on when you're increasing the channel's preamp gain (rotary dial, not fader).
  7. It doesn’t even get hot enough to go to the red lights. It hovers on the yellow half way when the gain is turned 3/4 up. Like I said I don’t think the “fart sound” is speakers clipping. I think it’s something the preamp from the bass amp is sending, cause the channel doesn’t seem to be clipping looking at the board lights.

    I tried a TRS to TRS and a TRS to XLR. Both had the same problem except the background noise floor static was much louder with the TRS to XLR in the channel.
  8. DirtDog


    Jun 7, 2002
    The Deep North
    Well, that amp's line out is post-eq so maybe trying adjusting the amp's EQ to dial out that fartiness? But if it's not clipping, that's kind of weird.

    Do you get there same farty result on other channels on that board? Preamp could have gone funny on that one channel.
  9. I’ll definitely try another mixer channel to see. I’m not near it currently. The eq did very little in adjusting the farty sound. It correctly tone shapes, just little to do with the farty sound.
  10. el murdoque

    el murdoque

    Mar 10, 2013
    I've played the LA-12 multiple times into mixers, live and recording. Using a fair bit of bass boost and a five string, no problems there.
    To troubleshoot your problem, I'd try and play the bass directly into the mixer, without the SWR entirely and see what happens. The next thing would be another instrument (take a guitar if there's no bass at hand) into the SWR into the mixer.
    It could be an issue with the crossover or EQ. Do any of these clip when you play low?
  11. No, bass guitar, guitar and other instruments sound fine straight in. It’s going through the preamp that’s the problem.
    Last edited: Nov 8, 2019 at 9:16 PM
  12. A passive DI from the pawn shop is $5-$20 bucks and would eliminate this issue without paying a tech for repair or buying a different amp. Always nice to have for backup in case the amp dies.
  13. SpazzTheBassist


    Jun 20, 2006
    This entirety depends on whether or not you want amp color in your tone to the board or if you want bass-only (or bass + your pedals) transparency with no amp color (basically, your bass amp is just your personal monitor).........I'm from the latter group - I can DI first and use a floor wedge and still sound like the way I want it if I absolutely had to (this has happened, too)....If you are like this, any DI would work, even an inexpensive passive one (I'm not snobbish about gear - I own basses that cost a few thousand but I have no issue playing through a 20 dollar DI if it does what I want), although I'd recommend shopping around and particularly look at everything. Active ones, Sans Amp are always a good choice but even the Behringer one is very decent considering it's cost ( I have one).....Some processors have them built in, like my Zoom B3 which is what I currently use........If you are from the 'amp guy' category, I'd suggest looking at both DIs and mics or assessing what's built-in if that's an option... can't help ya there as amp/spkr color isn't my thing

    Good luck
    Last edited: Nov 8, 2019 at 10:45 PM
    b_carville likes this.
  14. Skip Chucker

    Skip Chucker

    Dec 9, 2018
    Eastern NC
    Dude, you got advice on what to do in your other thread (that asked the same question) from a guy who designs and builds amps for a living.

    Go do that...
    wintremute and FatBoutedGirls like this.
  15. or mic your bass cab..

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