Fender Rumble 500 ohm Speaker Change

Discussion in 'Amps and Cabs [BG]' started by CarlosAlmodovar, Dec 24, 2022.

  1. CarlosAlmodovar


    Dec 24, 2022

    The fender rumble 500 watts combo works as follows:
    Without an extension cabinet: 350W with 2/16 = 8 ohm (internal speakers)
    With an extension cabinet: 500W with 2/16= 8ohm (internal) - extension 8ohm = 4 ohm.

    I never use an extension cabinet, and my speakers are sounding funny lately (I gig a lot with high volumes).

    My question is: If I replace the 2 speakers (currently 16 / 2 = 8) with 8-ohm speakers ( 8 ohm / 2 = 4) aiming to use the 500 watts for the combo without an extension cabinet, that would work?

    In my opinion, will work but I don't know if fender has a special thingy to switch the power section only with an extension connected. If there's no thing a 4 ohm load should work for 500.
    Doctor Morbius likes this.
  2. Happy Holidays and welcome to Talkbass.

    First and foremost just swapping speakers in a bass cabinet without doing the research and subsequent calculations, can make things worse than better. You can get away with this in the guitar world, but not so much down in bassland.
    There are many more mechanical considerations of the speaker parameters to consider. Bas cabinets are designed for the speakers intended for them. Any variations can lead to poor results. Fender uses special design drivers in their cabs. Some off the shelf thing might not work as well.

    I also understand that there can be a trade-off between impedance and efficiency. So that might be a consideration as well.

    If you are interested in learning more about speaker T/S parameters and how they are affected by the cabinet, check here.

    Thiele/Small Parameters Explained. A beginner's guide.

    To address your immediate issue...
    Are you trying to run a lot of bass in your EQ setup on your amp, in addition to high power?
    If so, that can be a recipe for bad sound and possible speaker damage. (T/S parameters again, at play here.)
    Forget trying to wring out all you can from a low E or B. Our brains/ears don't interpret those low frequencies very well. Rather we key in on the harmonic (82 Hz for the E String for instance) and our brain fills in the fundamental.

    Trying to put too much power into the lower end also robs power from your mids. This can muddy your sound. Maybe that's what you are hearing?

    You may want to look at getting a High Pass Filter (HPF) to put between you bass and the amp's input. These do a better job of limiting the undesired lows than just the EQ settings on your amp.

    I know a lot of this seems counterintuitive, it's all been well discussed here for a long time. There are entire sub-forumd on these subjects here. There is also a Fender Rumble club with many people who will discuss your amp/speakers situation.

    Fender Rumble Club

    HPF pedal

    Be sure you are chasing the right problem before making expensive mistakes.
    Good Luck
    FRoss6788 likes this.
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The 210 drivers used in that combo are a well calculated balance between performance, sensitivity and power handling. The 8 ohm cabinet power rating is a good real world number.

    Of you do the math, you will discover how challenging it will be to improve on the current performance without spending more than the combo is worth.

    If it’s not enough combo for you, you will be much better off looking for a different combo (or amp/cabinet pairing. Alternatively, add the 210 extension cabinet for a much better experience.
  4. This is the answer for getting the most out of that combo, increased cone area= more volume and better tone, always.
    lowendrv, abarson and agedhorse like this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    It’s also the reason that combo was designed the way it was, the addition of the extension cabinets is an integral part of the original combo design.
    lowendrv, G-Dog and FRoss6788 like this.
  6. It will certainly "work" as I have done it. I've covered the external cab outlet with some tape to make certain I don't use it.

    As others have stated, the addition of an external 8 ohm cab would be better.
  7. JakobT


    Jan 9, 2014
    Oslo, Norway
    The best way to get the full use of the 500 watts and more volume is to add an extension cab. Replacing the existing drivers without knowing exactly what you’re doing is very much a hit-and-miss affair - mostly miss.

    Heeding the advice of @agedhorse and @Old Garage-Bander is strongly recommended.
  8. basscooker

    basscooker Commercial User

    Apr 11, 2010
    Northern KY
    Cab fan, hobbyist
    I noticed this little bit here at the end hasn't been addressed. No switch needed. Power output is on one side of the "=" while impedance is on the other side. By nature of lowering the impedance, the power increases. No magic, just math.

    Get the extension cab if the combo can't do it on its own; or consider earmarking some pennies and nickels for a different rig when you can swing it. You'd really be hard pressed to improve the combo for less than adding a cab.