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Suitable Attenuator For Mesa Bass 400+ Rig?

Discussion in 'Amps and Cabs [BG]' started by sludgehead, Nov 20, 2018.

  1. sludgehead

    sludgehead Supporting Member

    Aug 9, 2007
    Forgive me if attenuators in general have been discussed previously on this forum; I did a search and the results didn't clearly indicate it.

    Anyway, I've got this Mesa Boogie Bass 400+ running through a 4ohm Crate 2x15" cab. Some of you probably know how burly of an amp this is. I can have the master set at just under 3 and it is ungodly loud. My drummer can't hear anyone else but me (and his skull rattling).

    I realized that I need some sort of attenuator. So recently I grabbed this Behringer rackmount compressor I had laying around and set it up in the effects loop with the blend all the way wet. The compressor threshold and ratio settings aren't crushing the signal, but I have the output gain down about 5db. This seems to help the overbearing master level. I can now have it at about 4 or 5 with the input gains pretty high for a nice drive at a manageable level.

    Two things though:

    1. I don't feel like this is the best way to do it
    2. Sometimes the compressor clips out depending on which bass I use (a Squier Tele with the mudbucker puts it in the red easily). There's a nasty high end frap at times.

    The question I have - are there attenuators that are suitable for bass amps of this high wattage? I've searched and found some boxes selling for pretty cheap (Carl's Custom Guitars makes one) but they are more for Fender combos, low wattage Orange heads; mostly guitar related amps.
  2. BeauZooka


    Oct 2, 2007
    Seattle USA
    Here's a off the mark but possible solution for you:
    Wire your cab so you have separate jacks for each 15" speaker. Then you can plug in one speaker or both as needed. Running just one speaker should drop the volume quite a bit.
  3. mesaplayer83


    Jun 27, 2017
    IMO, the above is a better solution than attempting to attenuate a big tube amp...
    basscapes and Aqualung60 like this.
  4. Wasnex


    Dec 25, 2011
    I have followed several related threads on this over the last year or so.
    Big attenuators
    building a 'speaker motor' load box
    Recording V-4B using attenuator, load etc.

    As far as I know there are no off the shelf variable attenuators that can handle a 400+.

    You could build a home brew solution using large power resistors and some sort of switching network.
    sludgehead likes this.
  5. sludgehead

    sludgehead Supporting Member

    Aug 9, 2007
    Thanks for the replies.

    BeauZooka - the strange thing about this cab is that there are two inputs in the back. Plugging in either of them seems to power both speakers at the same time. I replaced the speakers when I got the cab from a friend but this was about 3 years ago. At the time I wasn't thinking closely about exactly how they were wired, or was familiar with series v. parallel speaker wiring. I simply just installed them exactly how the old ones were set up.

    The more I read about attenuators, the more I'm leaning towards changes to my cabinet/speakers instead.
    JohnnyChatter likes this.
  6. BeauZooka


    Oct 2, 2007
    Seattle USA
    They are probably 2 x 8ohm speakers wired parallel to 8 Ohm. Then just a jumper from one jack to the other.
    Just remove the jumper and wire each speaker to their own jack separately.
    Aqualung60 likes this.
  7. I used to have a 400+. It seemed to me that not only was it a fairly loud amp, but the master volume seemed to make a huge jump at a low number, can't remember exactly,maybe 2-3 or so, rather than a nice smooth progression. I always ran the master fairly low and it was pretty loud. Is it possible to turn the master, slowly and carefully, lower than 3? The input volumes also can be turned down. If that fails, the graphic EQ can be used to cut all frequencies, approximating a cut in volume.
    Downunderwonder likes this.
  8. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    fu22ba55 likes this.
  9. Yerp. I am sure they meant well but that wasn't what they meant by wire them individually. Doing what they meant would also drive both speakers, likely to destruction, unless they are in their own enclosures. The undriven one doesn't just sit there, it flaps in reverse unloading the whole box. Don't do that.
    tchristian likes this.
  10. Using the compressor unit as a pad is the same as turning down the master attenuator.

    Using it as a compressor makes you sound compressed.

    Don't confuse the two.
    Last edited: Nov 20, 2018
    Microbass and agedhorse like this.
  11. Fire the drummer.
    Microbass and BassManKK like this.
  12. This is the correct approach.
  13. hell no. See above. You can only do that if the drivers don't share a common backspace.
    trevcda likes this.
  14. JimChjones


    Aug 6, 2017
    SE England
    Assuming its a ported enclosure there's also the issue that the effective box volume has doubled and the porting no longer works correctly.
  15. Specs and claims are fantastic.

    Other option for half the money, used Trace Elliot Elf.
    coreyfyfe likes this.
  16. fu22ba55

    fu22ba55 Supporting Member

    Apr 16, 2009
    I say use the RockCrusher coreyfyfe mentioned.

    I used a Tom Scholz Power Soak for years with my SVT. PowerSoak was only rated at 120 watts, but as long as I only used it in the first or second level of resistance (not very much, but enough to get sound men off my back), it would last a couple years before melting down.
  17. Wasnex


    Dec 25, 2011
    Is the "Mini" new? Last time I checked Rockcrusher specs it couldn't handle anywhere near that much power.
  18. sludgehead

    sludgehead Supporting Member

    Aug 9, 2007
    Yes, it most certainly has a very huge jump between 1.5 and 2.5. I never really mess with the graphic EQ but it may be worth a shot. Turning the input volumes down would give me less drive, so I wold prefer not to do that.

    Hell no! Your other advice is helpful though.
  19. Wasnex


    Dec 25, 2011
    There may be a bit of creative and somewhat misleading marketing BS going on here.

    From the webpage: "Even SVT owners can ditch their cabinet and safely load their 300watt amp when in the 4 or 16 ohm position."

    From the Manual (attached):
    YOU MAY NOT EXCEED THE 100W RMS or 150W PEAK POWER RATING OF THE MINI ROCKREC while in 8 OHMS or 150W RMS or 300W PEAK POWER in 4 or 16 OHM setting.​

    First of all, don't hook an SVT to a 16 ohm load unless your goal is to release the magic smoke. Second, healthy SVTs and 400+s can easily exceed these power ratings when pushed. I have multiple references references that indicate these amps commonly bench test around 260-270W RMS with fresh tubes. I believe the theoretical Peak power would be double the max clean RMS measurement.

    So while you can run big tube amps on the RockRec...you might experience a melt down if your goal is heavy output drive.

  20. Gearhead17

    Gearhead17 Supporting Member

    May 4, 2006
    Roselle, IL
    When I had the 400+, I replaced one of the preamp tubes with an ECC83 JJ Tubes (I think?). It made the controls on the amp much more gradual and the volume was easier to adjust. Without that tube adjustment, increasing the volume to three resulted in CRAZY VOLUME. That may not be the solution, but it definitely makes the amp more adjustable. I was looking for that thread and was unable to find it. Before 2011 it was written.

    A lower efficiency cab the sure fire bet.

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