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adding a rolls crossover plus some distortion on top.. what else?

Discussion in 'Effects [BG]' started by sears, Apr 14, 2014.

  1. sears


    Aug 7, 2005
    ec, md
    Currently I run a passive bass into a Markbass Compressore which is on all the time.

    I'd like to add some distortion on top.

    Could I run

    bass > compressore > rolls sx21 crossover

    > high: turbo rat (for now)

    > low: nothing

    > Boss LS-2

    and put the mixed signal back to the amp?

    Would I need a boost or buffer (a la JimmyM's recent thread) before the Rolls sx21, or is it worth trying as I describe it? Will there be any phase issues with an active mixer pedal?

    I thank you for your expertise!
  2. Try the compressor in the low loop, or at the end after both signals are blended back together. I personally don't like a compressor before distortion as I like to get more overdrive the more I dig in, and compression would be fighting that.

    Since the distortion will be compressing your mids and highs, clean compressed lows would help keep the overall balance in check.

    You would only need a boost or buffer in between if you are trying to hook up a passive bass straight into the Rolls, since it probably doesn't have a high impedance instrument input. The compressor would count as a buffer.
  3. Some distortions bounce the phase. If the phase is opposite on the returning effected highs, the blended signal has a dropout in the crossover frequency zone.

    Even with a blender that has phase adjustment, switching the pedal to bypass flips it back again. I fixed that by getting a multichannel blender with phase control, using last channel in series to flip phase when needed.

    You can also get a 2nd blender pedal set with phase flipped and 100% wet, to kick in when needed.
  4. BrBss

    BrBss Supporting Member

    Jul 9, 2010
    I use the rolls crossover and a small Nady mixer.
  5. sears


    Aug 7, 2005
    ec, md
    Food for thought. I actually have a two-channel Mackie mixer but do I really want a giant pedalboard? My compressor is big enough.

    But it sounds like I can run a passive instrument into the Rolls, or at least give it a try.
  6. zwkoch

    zwkoch You can't do that on bass enthusiast Supporting Member

    Nov 29, 2012
    Twin Cities, MN
    Check out the Brimstone Audio XD-1. It is a distortion pedal with built in, selectable crossover. It will allow you to distort just the higher frequencies and keep the low end clean. Also has a lot of EQ options. All in one package, no phase issues.
  7. You can't run passive bass into the sx21.

    I run mine from BDDI Deluxe. The sx21 lives on the underside.
  8. sears


    Aug 7, 2005
    ec, md
  9. If you want to try the clean compressed lows + distorted mids/highs idea out without having to plug your passive bass straight into the Rolls, try:

    Bass -> LS-2 (set to A+B Mix) -> Loop A out -> Rolls

    Then from there, send the highs to the RAT, the lows to the compressor, then both of those go into the A/B return sockets of the LS-2.
    jeffgnr90 likes this.
  10. That will work provided the rat doesn't flip phase.
  11. Don't think the RAT will, not sure about the compressor though!
  12. Savage_Dreams


    Jan 8, 2007
    "The sx21 lives on the underside."


    and why cant you run a passive bass into it?
  13. Savage_Dreams


    Jan 8, 2007
    im learning more ways the ls-2 works all the time as far as what feeds out and works back in, and you just inspired a great change in my rack. thank you!
  14. Underside as in hidden under the pedal board.

    And the Rolls SX21 has an input impedance of 10 kΩ, designed to take an input from an active electronic device, rather than a passive pickup/volume/tone control. A passive bass pickup wants to be connected to something much higher like 1 MΩ (100x higher), otherwise you lose all the high frequencies.
  15. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    looking at the Rolls schematic, it has a 10K resistor from the input jack's hot to ground (to give it a 10K input impedance). since it uses 4560 opamps, i'm wondering if just replacing that resistor with a 1Meg one would work to raise its input impedance and work with passive instrument levels.
  16. sears


    Aug 7, 2005
    ec, md
    Genius. I'm going to download the manual to make sure I completely understand this before proceeding.

    Maybe Rolls would offer a factory mod or at least some guidance.
  17. ga_edwards


    Sep 8, 2000
    UK, Essex
    Have a look at the EBS Billy Sheehan signature drive too. It has separate clean and drive channels, each with their own effect loop. So you could put a crossover in the dirty loop to remove the low end and tailor the sound to your liking - or as I do, an eq pedal to properly shape the distortion.

    What you could also do going a stage further is to put your compressor in the clean channel for compressed clean and uncompressed drive. Works really well for me. Only downside is the effects loops are bypassed when the pedal is bypassed, so I leave it permanently on with an on/off pedal in the dirty loop.
  18. sears


    Aug 7, 2005
    ec, md
    I bugged Danny a number of times via PM and ordered the parts. Thanks dannybuoy!!

    Here's what happens. Since you're not plugging anything into the "Send B" jack, the LS-2 mixes that unconnected wire sound in with the crossover action that's happening in Loop A.

    This creates an unacceptable amount of hum. Is there a DIY cable you can make which will terminate its own signal?