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Fender Rumble V3 mod: separating amp and speaker

Discussion in 'Amps and Cabs [BG]' started by eric_B, Apr 13, 2016.

  1. Time to separate the amp from the cab in my 500 combo.
    I didn’t need to remove the amp unit from the cab at all.
    Parts: speaker cable, female D-type connector, D-type mounting panel, some wires, shrink wrap and screws.
    Tools: drill, contour saw, tape, soldering tool, heat pistol, glue gun and vacuum cleaner.


    Here we go, main parts are shown above.


    Marked the location for the panel, needs to be off-center to avoid the internal reinforcements of the cab.


    No turning back now, but the hole aligned very well!


    The inside of the combo, view from the new rear hole.
    Black is neg, white is positive, make sure to cut the two coming from the amp.


    Removed the connectors from the amp, I also realized that the dampening foam on the rear needed to be glued back on after the cutting.


    Foam glued back on.


    Cut, soldered and shrink-wrapped the plug coming from the amp.


    Soldered the speaker wires onto the female connector and did a successful test! All seems fine.
    The plug cable has a plastic thingy not seen now that will be screwed into the panel, allowing some smooth movement in/out, with a stop clamp on the inside to protect from tearing it too far.


    Only a few screws missing now to attach everything a 100%.
    Tried it out and all works fine.
    However, I’ll need to make a small arc-shaped protector solution to keep the plug out of harms way since it protrudes a slight bit.

    Attached Files:

    Last edited: Feb 17, 2018
  2. eric_B


    Apr 19, 2015
    The Netherlands
    That looks like a great job man, :thumbsup:
  3. All thanks to your inspiration brother
    eric_B likes this.
  4. Bobb Nagel

    Bobb Nagel

    Aug 30, 2000
    Chicago area
    Can you share where you sourced the parts for this mod? Panel, jacks, etc.
  5. Got all the parts except screws from Thomann.de.
    Wood screws for attaching the panel are available from any hardware store, jack/panel screw and bolt is M3 with a recessed bolt head.
    Bobb Nagel likes this.
  6. Did the final touches today.

    Kopia av IMG_6315.JPG

    Locking washers onto the M3 bolts to keep them from rattling loose.

    Kopia av IMG_6316.JPG

    One small issue is that the plug protrudes a bit from the rear face - I installed a few rubber bushings around the mounting bracket but it still lacks about 2 mm of protection. Should suffice I guess - if I need to really haul the combo hard into a crammed space I can always detach the plug to take it out of harms way.
    eric_B likes this.
  7. eric_B


    Apr 19, 2015
    The Netherlands
    Great, now it's time to enjoy your modded setup!
    Danne Palm likes this.
  8. GonePlaid

    GonePlaid "It needs a bridge cover" Supporting Member

    Mar 29, 2016
    Southeast FL
    You geniuses annoy hell out of the rest of us.lol
    Giffro, RedVee and Danne Palm like this.
  9. eric_B


    Apr 19, 2015
    The Netherlands
    You're welcome :D
    Danne Palm likes this.
  10. mmbongo

    mmbongo Regular Human Bartender Supporting Member

    Aug 5, 2009
    Nice work!

    But to be honest...I cringe when seeing all that sawdust all over the back of the drivers. Did you take them out before cutting the hole? If any of that sawdust gets down in those open pole pieces on the speakers, they are done for.
    GonePlaid likes this.
  11. BassmanPaul

    BassmanPaul Inactive

    I wonder how much these amps will be worth when it comes time to replace them? I suspect not a lot.
  12. eric_B


    Apr 19, 2015
    The Netherlands
    I took out the stock speaker and covered up the vents and connectors of the amp before cutting the hole.
    I reckoned the dust may do no harm but it wouldn't improve the sound either ;)

    Maybe not much, but who knows, maybe someone will like it. But I didn't (and don't) intend to sell my Rumble so it doesn't matter much to me.
    Also, I had no problems doing a fairly easy mod like this because it would not damage the combo in any operational way.
    And I can always restore the initial connection and just have the extra dish with 2 connectors on the back which may not be stock but doesn't look like a crap DIY job either. IMHO.
  13. bobcruz


    Mar 10, 2004
    Who cares? None of us who modded our combos does. We made them so much more useful to us, they ain't going nowhere. :thumbsup:
    Last edited: Mar 23, 2018
  14. LennyJ

    LennyJ Supporting Member

    Dec 10, 2001
    Acworth, Georgia
    I have a 100 and I called Fender and they said the amp is set as the combo to run at 100 watts with the single speaker and that running at 4 ohms could damage the amp. That was their story.

  15. eric_B


    Apr 19, 2015
    The Netherlands
    Yes, I got the same information, the amp was not designed for (and probably not tested at) 4 ohms.
    Does that mean it will blow up directly when it is connected to 4 ohms? I would say not but it could when you push the amp too much. But an amp designed for 4 ohms also could.

    Speakers don't have a lineair impedance curve. The impedance will vary (a lot) from the lowest to the highest frequency. So an amp has to be able to handle that.

    Check out the graph of an Eminence Deltalite 2510 speaker with a nominal impedance of 8 ohm: the impedance (the lighter red line) varies from around 6 to 65(!) ohms:


    I keep the level of my 100C in low (home studio) and use the modded functionality to try out other cabinets or fill out the sound of the 12" speaker and I haven't had any problems so far.
    But as always when modding: it is at your own risk.
    dralionux, AstroSonic and G-Dog like this.
  16. leerod054


    Sep 28, 2018
    I did a conversion on my R40. Used an Eminence PF10M(Ampeg Portaflex 10inch 8ohms) . Installed back plate with crossover board and a toggle cutoff switch along with a speakon. You wire the Output transformer to the speakon then solder the switch (one wire) to positive on speakon. Then solder other wire from switch to your crossover. Solder negative to speakon to run to crossover.
    Crossover goes to your speakers ( I say that cause I installed a Motorola tweeter) in your combo. The smitch will cut off combos speakers allowing you to use the speakon to an external cab. The amp of the combo is now usable on its own. Best heard with headphones or through desktop. .
    Last edited: Mar 10, 2019
    eric_B likes this.
  17. HiredGeek


    Feb 5, 2019
    Thank you @eric_B for this great idea. I modded my Rumble 200 to work with my Ampeg SVT-3. Only took me a few hours and under $20.

    Hosa 4-pole Neutrix connectors
    $6.50 each

    14-gauge Lamp cord - 1 foot bulk at Lowe's

    Disconnect terminal wire connectors, at Lowe's

    Neutrix dummy plug
    Neutrik NDL Dummy Plug For 2 & 4 Pole Speakon & PowerCON Jacks | Full Compass Systems

    MVIMG_20190530_221310.jpg MVIMG_20190531_022202.jpg MVIMG_20190531_024338.jpg MVIMG_20190531_035604.jpg MVIMG_20190531_040625.jpg

    You don't need to remove the combo amp - I did it unknowingly.

    I didn't connect the tweeter because I never use it (it sounds harsh imo), but I believe it could be done by adding a crossover.

    I put the neutrix running to the combo amp off to the side and plugged it off with the dummy plug, because I probably won't use it much, and I don't want to confuse the 2 connectors.

    Easy mod and sounds awesome!
  18. eric_B


    Apr 19, 2015
    The Netherlands
    Nice job! And it is an easy and cheap but very useful mod, I still like it.
  19. Hey thanks, this is great! Is it all hooked back the way it works originally ie horn and ext cab option when used as a combo as well as separate? Someone was mentioning it may take another procedure to get the horn working, I dunno just making sure.
  20. HiredGeek


    Feb 5, 2019
    The way I did mine, the tweeter works with the combo still. But for my separate amp, I didn't connect the tweeter because I didn't want it. That would require a "tweeter crossover" which is basically a high pass filter. Only highs get filtered to the tweeter and the rest of the frequencies go to the regular speaker. There's a crossover built into the circuit board of the combo amp on my Rumble 200. Theoretically I think you could tap into that crossover, but that's beyond my knowledge/ability. It might require power.
    As for the extension cab, you can use a Y cable like the OP used in the first post.
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