I've been curious about the ext speaker connection on the Rumble 800 (not Stage), seems like I've seen posts here about connecting TWO additional cabinets to it, but I never could make sense of the impedances and power outputs mentioned. So I found out that yes, you can do that, but as soon as you switch it to 4 ohms, it disables the internal speaker, which makes perfect sense to me. So it's rated at 800watts into 4 ohms, which you can only get if you either connect one external 8 ohm cab (with the switch set to 8ohms) or two external 8ohm cabs (with the switch set to 4 ohms), and the internal speakers are then disabled.
Forgive me if this has been made abundantly clear already, but I just needed to get it straight in my own mind, which it is now. ... ... ... .
Incorrect parts are crossed out.
I don’t believe this is the case.
It's not!
Sonafagun, you're right! When I first tried it, the Kustom was so much louder, I thought the Rumble speaker was off. Didn't help that the Kustom speakers are more at ear level. It really really sounded like the Rumble speaker was just off, but tilting it up toward me just now, yeah, it's still working.
So forget everything I said . I'm still confused about the output power and impedance of the Rumble 800.
I will attempt to elucidate.
I agree that the labeling of the 800's Impedance switch can be confusing.
That's because it is written in reference only to the extension speaker(s), and the numbers are rounded off to boot! See below.
My understanding is: on 8 ohms, 400W goes to the internal speaker, and if present 400W to the 8 ohm cab. On 4 ohm setting, 300W goes to internal speaker, and 500W to the cab or cabs combining to 4 ohms. Do not use 4 ohm setting without a 4 ohm load on the external connector(s).
Pretty close, Sharpie!
- (USE 8ohm IF NO EXT. SPKR) - The internal speaker load is 8ohms. You may attach another 8ohm speaker load here while leaving the switch at the 8ohm setting. The amp automatically switches to 4ohm operation, just like the Rumble 200 & 500 do without this external switch.
- 400W 8ohm MIN - If you attach a 8ohm speaker load it should be rated to handle at least 400W.
- DISCLAIMER: While it's ideal that the extension cab be labeled for 400W, or greater, 7ender itself is very conservative with its ratings and labels! The 2x10" speakers in the Rumble Stage 800, which can see 400W, are exactly the same as those in the Rumble 210 cab officially rated and labeled at 350W! And though I've advised Rumble 800 (Stage & otherwise) users against using the officially rated and labeled 300W Rumble 115 cab, I have seen no one anywhere admit this combination had any problems! YMMV
- 500W 4ohm MIN - If you attach a 4ohm speaker load, either a single 4ohm or two 8ohms, it should be rated to handle at least 500W.
- DISCLAIMER: Actually, a 4ohm external load can draw up to 5
33W, leaving just
267W for the internal speakers! But this was written to "simplify" this setting. So, don't get so hung up on such details.

- SET SWITCH TO MATCH EXT. SPKR IMPEDANCE - This means to disregard the internal speaker load in this setting!! Yes, adding an 8ohm extension to the internal 8ohm load makes a 4ohm total load, but DO NOT USE THAT FOR THIS SWITCH SETTING. 7ender has worded this for "ease of use", or beginners, or something, making it confusing for anyone with a little knowledge of impedance!
So, there is no "disabling the internal speakers" in any scenario! It will allow too many speakers creating too little impedance and frying the amp! You need to read and heed, and understand the label and/or manual in this regard.
I hope this helps